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Relationship of life-history patterns to depth in deep-water caridean shrimps (Crustacea: Natantia)
Abstract
Deep-water shrimps, distributed on the steep outer reef slopes of tropical Pacific Islands, were obtained by setting baited traps in depths down to 850 m in the vicinity of Laucala Bay, Fiji, over the period 1979 to 1983. Life-history variables were estimated and interspecific comparisons made between Parapandalus serratifrons, Plesionika longirostris, Heterocarpus ensifer, H. gibbosus, H. sibogae, H. laevigatus (Pandalidae) and Saron marmoratus (Hippolytidae) which have different depth distributions. Results suggested that, interspecifically, reproductive lifespan tended to increase with increasing depth of distribution and that mean egg sizes of each species increased with increasing depth. Brood sizes tended to increase inconsistently with depth, although relative brood size (number of eggs per standar 15 g individual) appeared unrelated to depth. Although annual reproductive effort varied inconsistently with depth, reproductive effort totalled over the lifespan of the Heterocarpus species tended to increase with increasing depth. Some of the findings are counter to competition-based ecological theory, and it is proposed that adult predation decreases with increasing depth, allowing deeper-water species to have an extended lifespan, an increased degree of iteroparity, and a corresponding increase in lifetime reproductive effort. Further, we suggest that the probabilities of larval survival, which appear to decrease with increasing depth, are offset by the production of larger eggs by deeper-water species.
... Many caridean species inhabiting higher latitudes and depths are adapted with large size of egg and hatched larva, increased larval development, low fecundity and mortality (Clarke, 1993b;Wehrtmann & Kattner, 1998;Thatje & Bacardit, 2000;Anger et al., 2002). In tropical waters, increase in egg size and seasonality and low brood size were reported in pandalid shrimps inhabiting greater depth ranges (King & Butler, 1985;Company & Sarda, 1997). ...
... Deep-sea habitats provide adverse ecological conditions such as lack of seasonality of temperature, photoperiod, food availability which lead to low reproductive success (Bauer, 2004). Studies on marine decapods inhabiting the deep sea indicated higher female body sizes, large egg sizes and longer reproductive lifespan to overcome adversities of depth (King & Butler, 1985). In such habitats, many of these species are known to adopt abbreviated larval development (Gurney, 1942). ...
... It can be noted that G. investigatoris has higher relative fecundity (5 eggs mm 21 ) when compared with G. alata inhabiting northern Chile (Quiroga & Soto, 1997). However, availability of resources for embryo production varies considerably in different geographic regions whereby interspecific comparisons become difficult (King & Butler, 1985). A number of morphological and physiological adaptations to environmental conditions influence embryo production (Corey & Reid, 1991;Hines, 1991;Oh et al., 2002). ...
Details on size at first maturity, embryo number and size, brood chamber volume and reproductive output of deep-sea armoured shrimp, Glyphocrangon investigatoris caught off the south-east coast of India by using EXPO trawl from 633 m depth in FORV ‘Sagar Sampada’ are reported here. Eighty-four female shrimps ranging from 17.29–36.31 mm carapace length and 2.28–16.54 g weight formed 7.73% of total catch, 30% of which was constituted by embryo-bearing females. Regression of weight on carapace length revealed negatively allometric growth (r ² = 0.85, P < 0.01). The size at first maturity was estimated as 19.96 mm. The embryo number ranged from 55 to 233 with a mean of 120.24 ± 34 embryos and showed a positive correlation to body size. Embryo diameter varied between 1.0 to 3.34 mm and more than 50% of embryos constituted the 2.0–2.5 mm size class. Brood chamber volume and percentage frequency of embryo stage development revealed a linear relationship with carapace length. Based on dry weight, mean reproductive output was estimated to be 0.16. The female armoured shrimps showed a high reproductive investment evidenced from few, large, yolky embryos, indicating their deep-sea adaptation.
... Plesionika species are small and intermediate sized shrimps ranging from 6-29 mm carapace length (Vafidis et al. 2005). Several studies reported that they have a clear segregation on size and depth and thus each species has a preferred depth range (King & Butler 1985;Company & Sardà 1997;Carbonell et al. 2003). ...
... The longevity varies depending on the body size and the depths of distribution. Larger-sized species inhabit deeper waters compared to smaller-size species (King & Butler 1985;Company & Sardà 1997) and deeper water species exhibit longer life cycles compared to shallow water species (King & Butler 1985;Ahamed & Ohtomi 2012). Therefore, the species inhabiting Atlantic are larger with longer lifespan compared to Asian species. ...
... The longevity varies depending on the body size and the depths of distribution. Larger-sized species inhabit deeper waters compared to smaller-size species (King & Butler 1985;Company & Sardà 1997) and deeper water species exhibit longer life cycles compared to shallow water species (King & Butler 1985;Ahamed & Ohtomi 2012). Therefore, the species inhabiting Atlantic are larger with longer lifespan compared to Asian species. ...
The pandalid genus Plesionika Bate, 1888 includes 93 species and has a widespread distribution including mainly subtropical and tropical waters and some temperate waters, but most species can be found in the Indo-West Pacific. The species of this genus are benthic or nektobenthic, feeding on pelagic and benthic resources. Up to the present, the occurrence of 45 species of the genus has been reported from Asian waters. However, studies on these species from this region are mainly concerning their taxonomic report and very less their biology. Herein a key for the 45 Asian Plesionika species, and brief notes on its taxonomy are provided.
... Such shifts are generally thought to occur as a function of temperature (Childress et al. 1990, Childress 1995 or locomotory capacity (Childress et al. 1990, Company & Sardà 1998, Seibel & Drazen 2007 and only recently has water depth been considered important (see Ikeda 2013). Egg size, a proxy for energy investment per embryo, has been shown to increase with depth (King & Butler 1985, Gage & Tyler 1991, Van Dover & Williams 1991, Mauchline 1995, Morley et al. 2006, Scheltema & Williams 2009). Egg size is, in most cases, related to lipid content (Anger et al. 2002); larger eggs have greater lipid reserves, allowing offspring more energy for development (Anger 2001). ...
... Egg size is, in most cases, related to lipid content (Anger et al. 2002); larger eggs have greater lipid reserves, allowing offspring more energy for development (Anger 2001). These reserves facilitate longer larval duration and help sustain development through non-feeding periods (King & Butler 1985). A depth-associated increase in egg size has usually been attributed to the low temperature and intermittent food availability typical of the deep sea (King & Butler 1985, Gage & Tyler 1991, Van Dover & Williams 1991, Morley et al. 2006; increased lipid reserves help mediate these challenges. ...
... These reserves facilitate longer larval duration and help sustain development through non-feeding periods (King & Butler 1985). A depth-associated increase in egg size has usually been attributed to the low temperature and intermittent food availability typical of the deep sea (King & Butler 1985, Gage & Tyler 1991, Van Dover & Williams 1991, Morley et al. 2006; increased lipid reserves help mediate these challenges. ...
Hydrostatic pressure is the most constant physical parameter on Earth. It increases linearly with water depth and is stable over evolutionary timescales. Despite this, bathymetric shifts in physiological adaptations that are observed in marine invertebrates (e.g. in metabolic rate and egg size) are currently interpreted to result predominantly from decreases in temperature. However, analyses of invertebrate egg size data presented here indicate an increase in egg volume with depth in the absence of a thermal gradient. This suggests hydrostatic pressure may also be important in determining resource allocation to offspring. To test the hypothesis that an increase in energy expenditure during development occurs with increasing hydrostatic pressure, we examined the effects of sustained exposure to pressure (1, 100, 200 and 300 atm) on development of a shallow-water marine gastropod, Buccinum undatum. Embryos developed successfully at 1, 100 and 200 atm, but the rate of development slowed with increasing pressure (by 3 d at 100 atm and 6 d at 200 atm). No development was observed at 300 atm. In embryos reared at 200 atm, veliger dry weight and carbon and nitrogen biomass were significantly reduced. These results indicate that high pressure significantly increases the metabolic cost associated with development, demonstrating a negative and ultimately critical effect. We hypothesise that pressure imposes increased metabolic cost on all physiological processes. This offers an additional explanation for physiological adaptations observed with increasing depth, indicating that hydrostatic pressure is an important and previously underestimated factor contributing to metabolic theory for most of our biosphere. Hydrostatic pressure may represent a critical physiological limit for the maximum depth distribution of shallow-water fauna.
... Reproductive effort has been defined as the proportion of the resources, available to the individual, which is allocated to reproduction as opposed to the other activities (Gadgil and Bossert, 1970) and was estimated as the percentage between the weight of eggs and the body weight, according to King and Butler (1985). ...
... The egg size of P. martia from the eastern Ionian coincides with that from Iberian waters (Company and Sardà, 1997), and both are smaller than that reported from the western Ionian (Maiorano et al., 2002). Egg sizes of the five deep-water Mediterranean pandalids have been reported to be similar and not correlated to depth of maximum occurrence of the species concerned, whereas in the tropical pandalids, egg size increases with depth of maximum occurrence (King and Butler, 1985). This different trend between Mediterranean and tropical pandalids was attributed (Company and Sardà, 1997) to the difference in vertical temperature profiles between the areas; in contrast to the isothermic Mediterranean waters deeper than 200 m, larger temperature ranges in the tropical waters are suggested to favor larger eggs in deeper water species and, thus, more competent larvae. ...
... In another, shallower water pandalid, Plesionika narval (Fabricius, 1787), an increase of egg size with depth has been observed in the eastern Mediterranean (Thessalou-Legaki, 1992). Mean reproductive effort was found similar to western Ionian P. martia and the tropical pandalids (King and Butler, 1985;Maiorano et al., 2002). ...
The population dynamics, growth, and reproduction of the deep-water pandalid shrimp Plesionika martia were studied in the eastern Mediterranean Sea. Samples were collected monthly (July 1999–June 2000) at a depth range of 440–600 m between Zakynthos Island and Peloponnissos (eastern Ionian Sea, Greece). Additional samples were taken in April and May 2001. Size-frequency distribution revealed that mean female size consistently exceeded that of males throughout the year (CL range: 8–23.5 mm and 9.3–29.1 mm for males and females, respectively). Smaller individuals of both sexes occurred only at depths less than 500 m. Mean size of both sexes increased linearly with depth, whereas a less prominent trend of sex ratio in favor of females by depth was observed. The overall yearly and the monthly sex ratio were in favor of females except during winter, when the two sexes were equally represented. Carapace length–wet weight relationships showed negative allometry, for both males and females. Ovigerous females occurred year around, although the main reproductive season extended from April to October. The smallest ovigerous female was 11.8 mm CL, whereas the size at 50% sexual maturity (CLm50) was estimated as 16.16 mm. Fecundity and reproductive output were found loosely related to shrimp size. The von Bertalanffy growth curve parameters were estimated as: L∞ = 30.6 mm, k = 0.31 year−1 in females and L∞ = 28.2 mm, k = 0.53 year−1 in males. Regarding the major life history traits, P. martia from the eastern Ionian seemed to conform to those in other Mediterranean areas. Nevertheless, some population differences exist, which can be related to the oligotrophic conditions and the lack of fishing pressure in the studied area.
... Reproductive strategies differ widely between pandalid species as they exhibit a variety of sexual systems (gonochorism, protandrous hermaphroditism, or partial protandric hermaphroditism with primary males or primary females) and types of reproduction (semelparity vs. iteroparity), even within the same genus (e.g., Pandalus) (Correa and Thiel, 2003;Bauer, 2004). However, the species grouped in the tropical deep-water genus Heterocarpus are gonochoristic (King and Moffit, 1984) and typically iteroparous (King and Butler, 1985;Dailey and Ralston, 1986;Roa and Ernst, 1996). ...
... Deep-Sea Research I 57 (2010) 978-987 Poupin, 1994). Therefore, the contention of King and Butler (1985) that H. ensifer is a short-lived, semelparous species is questionable (Poupin et al., 1990), as their samples were collected in Fiji, a location within the Pacific region where the taxonomic identity of ''H. ensifer'' specimens has not been resolved (Poupin, 1994). ...
... The aim of the present paper was to examine population structure, sex ratio, critical sizes and ages pertaining to reproductive activities, reproductive period, type of reproduction, brood size, reproductive effort, and the potential trade-off between egg number and egg size in H. ensifer shrimps from the SW Gulf of Mexico. Based on studies conducted in other congeneric species (King and Butler, 1985;Dailey and Ralston, 1986), we hypothesized that these interrelated traits would reflect iteroparity and a substantial variation in reproductive effort for this species. ...
Heterocarpus ensifer is a tropical deep-water pandalid shrimp whose reproductive features are poorly known. We examined reproductive traits of a population of H. ensifer inhabiting the continental slope (311–715m in depth) off the Yucatan Peninsula, Mexico (SW Gulf of Mexico). Size range of the total sample (n=816) was 10.4–38.9mm carapace length. Females grow larger than males, but both sexes mature at 57% of their maximum theoretical size and at ∼30% of their total lifespan. Among adult females, the proportion of ovigerous females was high in all seasons, indicating year-round reproduction. Most females carrying embryos in advanced stages of development had ovaries in advanced stages of maturation, indicating production of successive spawns. In the autumn, however, the proportion of ovigerous females and the condition index of these females were lower compared to other seasons. This pattern potentially reflects a reduction in food resources following the summer minimum in particulate organic carbon flux to the deep benthos, as reported in previous studies. Spawns consisting of large numbers (16024±5644, mean±SD) of small eggs (0.045±0.009mm3) are consistent with extended planktotrophic larval development, an uncommon feature in deep-water carideans. Egg number increased as a power function of female size but with substantial variability, and egg size varied widely within and between females. There was no apparent trade-off between egg number and egg size and neither of these two variables was influenced by female condition. These results indicate iteroparity and a high and variable reproductive effort, reflecting a reproductive strategy developed to compensate for high larval mortality. The present study provides a baseline to compare reproductive traits between Atlantic populations of this tropical deep-water pandalid.
... Despite the variations in habitat characteristics among the regions, the longevity (~3.5 years) and number of cohorts (three) were similar to that previously estimated for P. edwardsii in the Pacific Ocean and Mediterranean Sea (King and Butler 1985;Colloca 2002). This finding may suggest a low degree of geographic heterogeneity in P. edwardsii species (Colloca 2002) and could have far-reaching implications for fishery management, which could be developed on a regional scale. ...
... When dealing with the sustainability of this stock in the Azores, the values obtained from the maximum yield per recruit (E RMY ) and economic optimum rate (E −10 ) can be considered low and very close to the 50% depletion of stock biomass (E −50 = 0.35-0.36). These results, combined with the life-history characteristics, confirmed that P. edwardsii, as well as most shrimps of the pandalid family, is a relatively long-lived, slow-growing and late to maturity species (King and Butler 1985;Colloca 2002;Santos et al. 2021), which makes this stock less resilient and highly vulnerable to overfishing. Additionally, despite the extensive (~1 × 10 6 km 2 ) exclusive economic zone (EEZ), the available areas for deepwater fisheries for crustaceans are very limited in the Azores . ...
The global overfishing scenario of the historically exploited marine stocks have generated concern and encouraged the search for new potentially exploitable fisheries resources. In this sense, shrimps are potential alternative resources to be exploited, given their high diversity and stock resilience. This study had an objective to estimate life-history traits and analyse yield and abundance fishing levels to see whether Plesionika edwardsii shrimp is vulnerable to overexploitation or not in the mid-North Atlantic (Azores region, ICES Subdivision 10a2). The females showed larger L ∞ (asymptotic length) and k (coefficient of growth; L ∞ = 27.3 mm, k = 0.75 year −1) than did males (L ∞ = 24.58 mm, k = 0.73 year −1). The mortality rates of males (Z = 1.00 year −1 ; M = 0.84 year −1) and females (Z = 0.92 year −1 ; M = 0.85 year −1) were very similar. In terms of longevity, the males (3.47 year −1) survived longer than did females (3.34 year −1). Depletion experiments showed a fast and straightforward decline of CPUEs (3, 5 and 9 days), confirming a low mobility and vulnerability to high fishing efforts. The maximum sustainable yield (MSY) estimates (5.4-10.7 tonnes (Mg) year −1) showed a low annual sustainable catch. These values combined with the life-history characteristics indicated that this stock is less resilient and highly vulnerable to overfishing.
... Despite the variations in habitat characteristics among the regions, the longevity (~3.5 years) and number of cohorts (three) were similar to that previously estimated for P. edwardsii in the Pacific Ocean and Mediterranean Sea (King and Butler 1985;Colloca 2002). This finding may suggest a low degree of geographic heterogeneity in P. edwardsii species (Colloca 2002) and could have far-reaching implications for fishery management, which could be developed on a regional scale. ...
... When dealing with the sustainability of this stock in the Azores, the values obtained from the maximum yield per recruit (E RMY ) and economic optimum rate (E −10 ) can be considered low and very close to the 50% depletion of stock biomass (E −50 = 0.35-0.36). These results, combined with the life-history characteristics, confirmed that P. edwardsii, as well as most shrimps of the pandalid family, is a relatively long-lived, slow-growing and late to maturity species (King and Butler 1985;Colloca 2002;Santos et al. 2021), which makes this stock less resilient and highly vulnerable to overfishing. Additionally, despite the extensive (~1 × 10 6 km 2 ) exclusive economic zone (EEZ), the available areas for deepwater fisheries for crustaceans are very limited in the Azores . ...
The global overfishing scenario of the historically exploited marine stocks have generated concern and encouraged the search for new potentially exploitable fisheries resources. In this sense, shrimps are potential alternative resources to be exploited, given their high diversity and stock resilience. This study had an objective to estimate life-history traits and analyse yield and abundance fishing levels to see whether Plesionika edwardsii shrimp is vulnerable to overexploitation or not in the mid-North Atlantic (Azores region, ICES Subdivision 10a2). The females showed larger L ∞ (asymptotic length) and k (coefficient of growth; L ∞ = 27.3 mm, k = 0.75 year −1) than did males (L ∞ = 24.58 mm, k = 0.73 year −1). The mortality rates of males (Z = 1.00 year −1 ; M = 0.84 year −1) and females (Z = 0.92 year −1 ; M = 0.85 year −1) were very similar. In terms of longevity, the males (3.47 year −1) survived longer than did females (3.34 year −1). Depletion experiments showed a fast and straightforward decline of CPUEs (3, 5 and 9 days), confirming a low mobility and vulnerability to high fishing efforts. The maximum sustainable yield (MSY) estimates (5.4-10.7 tonnes (Mg) year −1) showed a low annual sustainable catch. These values combined with the life-history characteristics indicated that this stock is less resilient and highly vulnerable to overfishing.
... In contrast, when resources are scarce and environmental conditions are harsh, selection will be in the direction of producing larger, more robust larvae (Hutchings, 1991;Einum & Fleming, 1999;Closs et al., 2013). King & Butler (1985) reported that, in deep-water pandalid shrimps off the tropical Pacific Islands, egg size increases significantly with increasing depth. Mizushima (2008) showed a similar trend of larger eggs in deeper-living Japanese pandalids. ...
... Other decapod taxa, such as Antarctic lithodid crabs, also showed higher relative fecundity and smaller eggs in shallower species, whereas lower relative fecundity and larger eggs were recorded in deeper-living species (Morley et al., 2006). The trends toward increased egg size in deep-water crustaceans have been discussed in terms of adaptive strategies to fish predation (King & Butler, 1985) and low water temperature (Clarke, 1987;Thatje, 2004;Morley et al., 2006). Because many fish species inhabit shallower water layers, predation is the main cause of larval mortality for crustaceans, and consequently the chances of survival increase with increasing depth (Gosselin & Qian, 1997;Wangensteen et al., 2017). ...
The crangonid shrimps Argis hozawai, A. lar and A. toyamaensis, co-distributed in the Sea of Japan, exhibit intriguing differences in geographical and bathymetric distributions and in reproductive biology. Argis hozawai (150-250 m depth) and A. lar (200-300 m) are broadly distributed in the northwestern Pacific Ocean and spawn relatively large numbers of small eggs, whereas A. toyamaensis (250-2000 m) is distributed in the Sea of Japan and spawns a small number of large eggs. We examined the relationship between egg size and dispersal patterns in the deep sea by comparing genetic population structures using mitochondrial DNA sequence variation. We found little or no genetic divergence within the Sea of Japan for A. hozawai and A. lar, whereas there was a slight but significantly higher genetic differentiation in A. toyamaensis. This suggests that A. toyamaensis has lower dispersal ability than A. hozawai and A. lar, and therefore might maximize larval survival through larger size at hatching, with either direct or abbreviated larval development, to adapt to the deep-sea environment in the Sea of Japan. We also detected the effects of drastic environmental changes during the Pleistocene glacial periods on their demographic processes in the Sea of Japan.
... In contrast, when resources are scarce and environmental conditions are harsh, selection will be in the direction of producing larger, more robust larvae (Hutchings, 1991;Einum & Fleming, 1999;Closs et al., 2013). King & Butler (1985) reported that, in deep-water pandalid shrimps off the tropical Pacific Islands, egg size increases significantly with increasing depth. Mizushima (2008) showed a similar trend of larger eggs in deeper-living Japanese pandalids. ...
... Other decapod taxa, such as Antarctic lithodid crabs, also showed higher relative fecundity and smaller eggs in shallower species, whereas lower relative fecundity and larger eggs were recorded in deeper-living species (Morley et al., 2006). The trends toward increased egg size in deep-water crustaceans have been discussed in terms of adaptive strategies to fish predation (King & Butler, 1985) and low water temperature (Clarke, 1987;Thatje, 2004;Morley et al., 2006). Because many fish species inhabit shallower water layers, predation is the main cause of larval mortality for crustaceans, and consequently the chances of survival increase with increasing depth (Gosselin & Qian, 1997;Wangensteen et al., 2017). ...
The crangonid shrimps Argis hozawai, A. lar and A. toyamaensis, co-distributed in the Sea of Japan, exhibit intriguing differences in geographical and bathymetric distributions and in reproductive biology. Argis hozawai (150–250 m depth) and A. lar (200–300 m) are broadly distributed in the north-western Pacific Ocean and spawn relatively large numbers of small eggs, whereas A. toyamaensis (250–2000 m) is distributed in the Sea of Japan and spawns a small number of large eggs. We examined the relationship between egg size and dispersal patterns in the deep sea by comparing genetic population structures using mitochondrial DNA sequence variation. We found little or no genetic divergence within the Sea of Japan for A. hozawai and A. lar, whereas there was a slight but significantly higher genetic differentiation in A. toyamaensis. This suggests that A. toyamaensis has lower dispersal ability than A. hozawai and A. lar, and therefore might maximize larval survival through larger size at hatching, with either direct or abbreviated larval development, to adapt to the deep-sea environment in the Sea of Japan. We also detected the effects of drastic environmental changes during the Pleistocene glacial periods on their demographic processes in the Sea of Japan.
... A mature male also possesses an appendix masculina situated between the appendix interna and the endopod of the second pleopod (Fig. 3). Eggs are carried externally on the pleopods of ovigerous females, and brood sizes (the number of eggs carried) may exceed 30,000 on the larger Heterocarpus species (King and Butler, 1985). ...
... Length-frequency distributions may be arranged sequentially over an extended time period, allowing the progression of modes to be followed. This method has been used to estimate the growth of several species in Fiji (King and Butler, 1985), and growth curves for four species (sexes combined) are shown in Fig. 4. Heterocarpus laevigatus in Hawaii (Dailey and Ralston, 1986) and the Marianas (Moffitt and Polovina, 1987) appear to have similar growth characteristics; the von Bertalanffy growth parameters for shrimps from various locations are summarised in Table II. In general, males grow more quickly than females but reach a smaller ultimate size. ...
... Small egg size and high fecundity is a only work carried out on the comparative life-histories general feature in these seasonal breeding echino-of deep-water pandalid shrimps is that reported by derms. Rokop (1974Rokop ( , 1977, in studies at a bathyal King & Butler (1985), on Pacific pandalids off Fiji. station in the San Diego Trough off California at However, a study by Cartes (1993) is available on the 1240 m depth, found no evidence of reproductive sea-interspecific trophic relationships among the 3 deepest sonality for species belonging to various taxa (3 species pandalid shr~mps in the Western Mediterranean, Pleof bivalves. ...
... In individuals of Parapandalus narval of the Eastern Mediterranean living between 5 and 140 m, Thessalou-Legaki (1992) reported a brood size of 8593 eggs for a female of 20 mm CL, which is higher than the brood size found is this study for the shallowest species (Plevonika heterocarpus). King & Butler (1985) found increasing egg sizes, but not decreasing relative brood sizes, with depth in 8 species of deep-sea pandalid shrimps in the Pacific Ocean, distributed over similar depth ranges to the 5 species studied here. They also found a progressive increase in the maximum size of each species with depth, which was not observed in the Mediterranean pandalid species (Table 2). ...
Reproductive patterns and populations characteristics of 5 deep-water pandalid shrimp species of the genus Plesionika (Decapoda: Caridea) were studied between 150 and 1100 m depth in the Western Mediterranean Sea over the period 1991 to 1994, including monthly samples taken from November 1992 to October 1993. With the aim of establishing interspecific relationships among reproductive biology and population characteristics 2831 individuals of Plesionika heterocarpus, 1787 of P. edwardsi, 1601 of P. gigliolii, 3888 of P. martia and 928 of P. acanthonotus were analysed. Results show an increasing seasonality in reproductive periods from the shallowest species, P. heterocarpus (distributed between 82 and 699 m depth) with ovigerous females present throughout the year, to the deepest species, P. acanthonotus (distributed between 165 and 1550 m) with ovigerous females present only in late spring and early summer months. A possible link was hypothezised between deep-water pandalid shrimp breeding period and sinking particulate matter from primary production. A significant decrease in relative brood size (number of eggs per 'standard' 20 mm carapace length female) with increasing depth distribution of each species was found. No significant relationship between egg size and depth distribution was apparent. In 4 of the 5 species studied a differential depth distribution based on sex-ratio and intraspecific size composition by depth was found. The only species where no significant trend was found in sex-ratio by depth, P. acanthonotus, did not show differences in size composition by depth. A slight interspecific size overlap was observed. Sex-ratio and size composition by depth distribution are discussed in the light of trophic and reproductive behaviour of each species.
... In fishes this seems to be the case. There are reports that species of some invertebrate groups, mainly crustaceans, attain a larger size in the cold deep waters than their relatives in warm shallow waters (De Broyer 1977; Childress and Price 1978; King and Butler 1985; Mauchline 1988 Mauchline , 1995; Chapelle and Peck 1999). The phenomenon of larger size with increasing depth is called abyssal gigantism (Herring 2002; Nybakken 2001 ). ...
... Abyssal gigantism is not a general trend of the deepsea benthic fauna. It rather relates to some invertebrate groups such as in particular crustaceans like mysids, amphipods, isopods, and ostracods (De Broyer 1977; De Broyer et al. 1997; Childress and Price 1978; King and Butler 1985; Mauchline 1988 Mauchline , 1995). Taking into consideration macrobenthic invertebrates low food supply in the deep sea contributes to an overall decline in body size. ...
A new genus and species of Loricifera, Titaniloricus inexpectatovus (Pliciloricidae) represented by a new type of Higgins-larva is described from the deep sea of the Angola Basin. The new larva is characterized by its gigantic size which is unusual for larval Loricifera, by six rows of scalids on the unit of introvert and neck, by an additional transversal row of scales marking the anterior rim of the collar, by a high number of thoracic plates, by more than 160 longitudinal ridges forming plicae on the loricate abdomen, by tubular toes with a broad basal part and undulated cuticle, and by two pairs of long anterior setae. The exuvium of the presumable sixth instar Higgins-larva of T. inexpectatovus gen. et sp. n. functions as a shelter for several instars: a large simplified seventh instar larva which is paedogenetic and contains some rests of smaller Higgins-larvae, and rests of adult specimens. The paedogenetic or seventh instar larva is morphologically not identical with the sixth instar Higgins-larva from which it moults because of the following transformations: all body regions form a sack-like trunk on which only the scalids of introvert and neck persist as small protoscalids.
... These early studies did show, however, that H. laevigatus was potentially of commercial importance, with a preliminary maximum sustained yield estimate of 454-907 metric tons (t) derived for the Hawaiian Archipelago (Department of Land and Natural Resources 1979). More recently the Western Pacific Regional Fishery Management CouncilS (WPRFMC) has revised this estimate to 400-4,000 t. completed in the Marianas (including Guam) and Fiji (Wilder 1977;King 1983;King and Butler 1985;Moffitt and Polovina 5 ). ...
... were found in stomachs of tuna in Fiji, indicating perhaps some type of vertical migration in the water column. King (1985), based on work completed in Fiji, examined the question of iteroparity and semelparity in several genera of pandalid shrimp (Plesionika, Saron. Parapandalus, and Heterocarpus). ...
The recent rapid development of fisheries for the Heterocarpus laevigatus in Hawaii and elsewhere in the tropical Pacific has created the need for biological information to manage the resource. This study reports on a 16-month sampling program of commercial shrimp catches in Hawaii, during which the depth of capture, carapace length (CL), sex, and reproductive condition of 7,368 H. laevigatus were determined. The overall sex ratio of H. laevigatus was 1:1.16 in favor of females and depended on the depth sampled; there were relatively fewer females as depth increased. Seasonal variation in sex ratio was evident which may have been due to changing catchability and availability or a sex related dispersion pattern. Sex ratio also depended on size category, displaying a standard pattern with no evidence of protandry. Females mature at 40 mm CL (64% of asymptotic length) and ovigerous individuals are found year round. However, the main reproductive season is from August-February, with over 50% of females carrying eggs from October-January. Mature shrimp may undergo a depth rela.ted seasonal migration in synchrony with breeding. Mature males and females were found deeper (700 m) during the reproduc- tive season than not (550 m). Females apparently settle in deep water and migrate gradually to shallower water as they grow. Seasonal length-frequency data suggest H. laevigntus is not semelparous. Separate analyses of CL- frequency distributions of male and female shrimp indicate their von Bertalanffy asymptotic sizes are 57.9 and 62.5 mm CL, respectively. Growth coefficients (K) estimated by modal progression were 0.35 and 0.25 per year for males and females, and total instantaneous mortality rates were 1.51 and 0.73 per year, respectively
... These early studies did show, however, that H. laevigatus was potentially of commercial importance, with a preliminary maximum sustained yield estimate of 454-907 metric tons (t) derived for the Hawaiian Archipelago (Department of Land and Natural Resources 1979). More recently the Western Pacific Regional Fishery Management CouncilS (WPRFMC) has revised this estimate to 400-4,000 t. completed in the Marianas (including Guam) and Fiji (Wilder 1977;King 1983;King and Butler 1985;Moffitt and Polovina 5 ). ...
... were found in stomachs of tuna in Fiji, indicating perhaps some type of vertical migration in the water column. King (1985), based on work completed in Fiji, examined the question of iteroparity and semelparity in several genera of pandalid shrimp (Plesionika, Saron. Parapandalus, and Heterocarpus). ...
Overall sex ratio was 1:1.16 in favor of females, there were relatively fewer females as depth increased. Seasonal varition in sex ratio was evident which may have been due to changing catchability and availability or a sex related dispersion pattern. Sex ratio also depended on size category, displaying a standard pattern with no evidence of protandry. Females mature at 40mm CL. Ovigerous individuals are found year round, but the main reproductive season is August-February, with >50% of females carrying eggs from October-January. Mature shrimp may undergo a depth related seasonal migration in synchrony with breeding. Mature males and females were found deeper (700m) during the reproductive season than not (550m). Females apparently settle in deep water and migrate gradually to shallower water as they grow. Seasonal length-frequency data suggest H. laevigatus is not semelparous. Growth coefficients (K) estimated by modal progression were 0.35 and 0.25 per year for males and females, and total instantaneous mortality rates were 1.51 and 0.73 per year, respectively.-from Authors
... Similar results are obtained by Ardizzone et al.(1990) Froglia (1982) . King & Butler (1985)observed that deep-sea shrimp species show longer life span compared to shallow water species. In general, shrimps are a fastgrowing and short-lived species (Abello et al., 2002). ...
Deep-water rose shrimp Parapenaeus longirostris (Lucas, 1846) is one of the most economically
important target species by coastal trawl fishery in the Mediterranean coast of Morocco. However, up to date
no published information is available on biology, population dynamics, management and conservation of
this species for that area. So, this study aimed to describe biological aspects, population parameters through
collecting monthly randomly samples of P. longirostris from coastal trawl fishery operating between Fnideq
and El Jebha and landings in M’diq port during the period from April 2017 to April 2018. Total number of
1510 specimens of P. longirostris was examined during the period 2017-2018, 66% were females and 34%
males. The overall sex ratio was in favour of females. The carapace length (CL) of all specimens ranged from
15 to 50 mm, with mean length 27mm and 35 mm for male and female respectively. A marked sexual
dimorphism was observed between males and females, the males were predominant in the smaller size classes
lower (< 30 mm) and female number increased gradually in the larger size classes (> 30 mm). All�morphometric relationships of P. longirostris showed a negative allometric growth pattern (b<3), and the
growth exponent (b) for females, males, and combined sexes ranged from 2.296 to 2.834. The estimated
growth parameters were L∞ =46.75 mm (CL), K =0.80 yr-1, t0=0.12.for male, L∞ =50.21 (CL)mm, K
=0.63yr-1, t0= -0.18. for females and L∞ =52.87 (CL) mm, K =0.39yr-1, t0= -0.35.for combined sex. P.
longirostris showed a diversified diet grouped into twelve group, and the most important food items for P.
longirostris were diatoms, molluscas and foraminifera. The monthly gonadosomatic index (GSI) changes
and ovary examination showed permanent reproductive activity all year round. The size and age (L50 and t50
at which 50% of the female population reached maturity were of 24 mm (CL) and 1.2 year respectively.
While the size at first capture was L50% = 27.25 mm (t50% =2.1 year) in the 2017-2018 period. Natural
mortality coefficient (M), total mortality coefficient (Z) and fishing mortality coefficient (F) during 2017–
2018 were estimated as 1.34 yr-1
, 3.49 yr-1
and 2.15 respectively. Exploitation rate (E) was estimated at 0.68
and per yield per recruit curve maximum is obtained at 0.75 (Emax) This indicates that at present the species
is exploited above the maximum exploitation level. The biological reference point (MSY) values of Fox and
logistic model are 66600 mt and 65300 mt respectively
... The peak season for both sexes was observed during November to February in the southwestern coast and December to February on the southeastern coast. The peak spawning period was observed during October to January in the southwestern coast, January to February in southeastern coast, which agrees with previous studies on pandalids (King & Butler, 1985;Hancock & Henríquez, 1968;Anderson & Lindner, 1971;Suseelan, 1985;Rajasree 2004;Rahool Shanis et al., 2014). There are several studies which have indicated that the extended reproductive period may be a typical feature of deep-water species in general (George, 1966;Gage &Tyler, 1991). ...
The caridean shrimp Heterocarpus chani Li, 2006 (Pandalidae), is widely distributed along the Indian coasts, and is commercially exploited by deep-sea fisheries in southern India. There is limited information on its reproductive biology. A total of 3,122 specimens were collected from commercial bottom trawlers with a 25–30 mm mesh cod-end at depths of 200–300 m between November 2013 and December 2015. There was no significant difference (P < 0.05) in the sex ratio, and size at first maturity with regard to the carapace length was estimated as 22.2 mm in females and 21 mm in males in Arabian Sea specimens and 22 mm and 20.8 mm, respectively, in Bay of Bengal samples. Ovigerous females were observed through the entire fishing season, which indicates year-round breeding, with three stages identified in the development of eggs (early, middle, and late stages). The estimated absolute and relative fecundity in ovigerous females ranged 830–45,650 eggs and 160–2,871 eggs g–1, respectively. The maximum of 45,650 eggs is the highest number so far reported for any pandalid species. The relationship between carapace length and fecundity revealed b values of 3.31 to 6.33, indicating positive allometry with the coefficient of determination (r2) of 0.21–0.37. Knowledge of the reproductive biology of the species can be further extrapolated aiming for the sustainable
management of this resource.
... In the mid-North Atlantic (Azorean region), unexploited virgin P. edwardsii populations mainly occurred from 200 to 400 m, which is suggested by Chan and Yu (1991) as the main occurrence range of the species. In other regions of the world, the depth range where the greatest abundances are observed varies from 100 to 150 m in Cape Verde (González et al., 2016), 150 to 200 m in Madeira (González et al., 2016), 150 to 300 m in the Canaries , 300 to 500 m in North Africa (Crosnier and Foster, 1973), 250 to 550 m in the Mediterranean Sea (Holthuis, 1987, Company andSardà, 1997;Carbonell and Abelló, 1998;, and is around 230 m in Martinique (Paulmier and Gervain, 1994), and 275 m in Fiji (King and Butler, 1985). Plesionika edwardsii inhabiting unexploited fishing grounds in the Azorean region are therefore found at the same depth as in the regions of Madeira, Canaries, Martinique and Fiji, and at a deeper depth than in the Mediterranean Sea and North Africa. ...
Plesionika edwardsii (J.F. Brandt in von Middendorf, 1851) is a cosmopolitan species that inhabits cold temperate and subarctic waters between 50 and 680 m. In the Azorean region, this is the second most abundant shrimp species and populations remain unexploited. To provide insights into a pristine state that can be useful for comparisons across regions and serve as a benchmark for a potential fishery in the future, we analyzed data collected during shrimp trap surveys in the Azores between 1999 and 2000. Plesionika edwardsii were caught between 100 and 600 m depth, with the biggest catches between 200 and 400 m. Sizes varied from 8.3 to 31.3 mm cephalothorax length (CL). Females were bigger and more abundant than males and predominated at depths up to 300 m. Ovigerous females were caught throughout most of the year, with a peak of abundance during the winter. The size at 50 % maturity was 25 mm CL. High variability in distributional patterns and life-history traits has been observed in our study and when compared with literature from other regions, it is difficult to distinguish which differences are potentially fishing-induced. Future studies should investigate the oceanographic processes associated with P. edwardsii ecology and commercial fisheries should be made on a precautionary basis.
... Metapenaeopsis siboage is found in deeper water than in M. barbata and M. dale. The difference between the longevities of the latter two species and M. sibogae could be attributed to differences in bathymetric distribution as reported by King & Butler (1985), who observed that deep water shrimp species exhibit longer life cycles compared to shallow water species. ...
We studied for the first time the recruitment, growth patterns, and longevity of Metapenaeopsis sibogae (De Man, 1907) using length-frequency method from monthly samples obtained from January 2013 to December 2014. We compared the von Bertalanffy growth function (VBGF) and the Pauly and Gaschütz growth function to the mean length-at-age data to identify any seasonal oscillation in growth rate and to suggest the best-fit model for describing growth. A single, short pulse of recruits of both sexes was observed from January to April, which was probably synchronized with the main spawning season with a time-lag of 3–4 months. Sexual dimorphism related to body size was found with the highest amplitude of body size recorded for females. We detected almost no seasonality in growth rate. The VBGF was adopted as the best fitting model to describe the growth of both sexes. The estimated equations were Lt = 16.79 [1 – exp {– 0.181 (t + 0.867)}] and Lt = 19.56 [1 – exp {– 0.139 (t + 1.928)}] for males and females, respectively. Growth differed significantly between the sexes. Longevity was estimated to be 27 months for males and 28 months for females. The relationship between carapace length and body weight showed negative allometric growth for both sexes.
... Changes in the population structure with depth have been reported for several species of pandalids, mainly for Pandalus borealis Krøyer, 1838 that showed clear stratification of size according to depth, with occurrence of larger individuals in deeper waters (Frechette and Parsons, 1981). Similar pattern was reported for P. edwardsii (Carbonell and Abelló, 1998), P. martia, P. heterocarpus (Vafidis et al., 2008) and Heterocarpus sibogae de Man, 1917 (King andButler, 1985) and opposite for H. ensifer and Heterocarpus laevigatus Spence Bate, 1888 (Gooding, 1984), which showed a decrease in size as the depth increases. ...
Analysis of abundance and population structure of Plesionika narval was performed on data concerning 5,255 specimens obtained from 62 fishing sets carried out off the Madeira archipelago (Northeastern Atlantic) between 2004 and 2008 in a depth range from 101 to 350 m. Abundance ranged from 0.01 to 19.74 specimens-per-trap and significant differences were found between seasons, probably as a result of an increment of population in the spring during the recruitment season. The analysis of size distribution revealed that the carapace length (CL) ranged from 2.45 to 28.61 mm and that mean female size consistently exceeded that of males. Differences in mean CL were statistically significant between depth strata and seasons. Of the specimens sampled, 57.00% were males, 41.88% females and 1.42% undetermined. Sex ratio also differed significantly between seasons according to depth strata, consolidating the hypothesis of the existence of seasonal migrations related with the reproductive cycle of this species. Ovigerous females showed larger sizes and occurred all year around and remain in shallow waters in winter, summer and autumn and move to deeper waters in spring. The highest frequency of ovigerous females was recorded in summer, between 151 and 200 m deep supporting the hypothesis that spawning of this species occurs in shallow waters, especially in late summer.
... In this context, one could think of abyssal gigantism (Herring, 2001) also as explanation for giant larvae. Mainly crustaceans have been reported to reach a larger size in deep-sea environments than their relatives in shallow waters (King and Butler, 1985;Mauchline, 1995;Chapelle and Peck, 1999). Low temperature and restricted food availability in deep seas are thought to decrease growth rates, but to increase longevity and the time span to reach sexual maturity (Nybakken, 2001). ...
The larval phase of metazoans can be interpreted as a discrete post-embryonic period. Larvae have been usually considered to be small, yet some metazoans possess unusually large larvae, or giant larvae. Here, we report a possible case of such a giant larva from the Upper Jurassic Solnhofen Lithographic limestones (150 million years old, southern Germany), most likely representing an immature cirripede crustacean (barnacles and their relatives). The single specimen was documented with up-to-date imaging methods (macro-photography, stereo-photography, fluorescence photography, composite imaging) and compared with modern cirripede larvae. The identification is based on two conspicuous spine-like extensions in the anterior region of the specimen strongly resembling the so-called fronto-lateral horns, structures exclusively known from cirripede nauplius larvae. Notably, at 5 mm in length the specimen is unusually large for a cirripede nauplius. We therefore consider it to be a giant larva and discuss possible ecological and physiological mechanisms leading to the appearance of giant larvae in other lineages. Further findings of fossil larvae and especially nauplii might give new insights into larval evolution and plankton composition in the past.
... A decapod's reproductive output (RO) is considered to be one of the most important aspects of its life history pattern (Torres et al., 2007). Interspecific comparisons of RO have provided much of the basis for theoretical considerations of life history strategies (Clarke, 1979;Hines, 1982;King & Butler, 1985;Torres et al., 2007), and intraspecific variations in RO are considered a prominent population characteristic of decapods (Torres et al., 2007). ...
The age and growth of conger eel, Conger myriaster, were investigated by measuring transversely sectioned sagittal otoliths samples from 635 individuals. Sample ages ranged from 1 to 13 years in the female data. Parameters of the von Bertalanffy growth function were estimated using nonlinear regression from back-calculation, mean length of samples at age relationships, and otolith weight-at-age relationships. Best-fitting value of the three methods was the otolith weight-at-age relationship (r² = .87). Parameters of otolith weight-at-age were estimated as L∞ = 143.76 cm, K = 0.081, and t0 = −1.285. Maximum oocyte diameter (MOD) ranged from 50 to 430 μm. Reproductive traits of ovaries showed a positive relationship between GSI and MOD (r² = .8515). It is suggested that oogenesis begins to develop from 4 years of age and at lengths of about 45 cm TL. In conclusion, these data provide reliable fundamental data for the fish stock management of Conger myriaster in South Korea.
... A decapod's reproductive output (RO) is considered to be one of the most important aspects of its life history pattern (Torres et al., 2007). Interspecific comparisons of RO have provided much of the basis for theoretical considerations of life history strategies (Clarke, 1979;Hines, 1982;King & Butler, 1985;Torres et al., 2007), and intraspecific variations in RO are considered a prominent population characteristic of decapods (Torres et al., 2007). ...
The age and growth of filefish, Thamnaconus modestus (Günther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 (P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL3.0536 (n = 1,692, r2 = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L∞ = 42.04 cm, k = 0.21 year−1 and t0 = −1.56 for females, L∞ = 41.20 cm, k = 0.18 year−1 and t0 = −2.36 for males, and L∞ = 43.16 cm, k = 0.17 year−1 and t0 = −2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters.
... RMF was mainly related to mass of individuals, indicating that the higher reproductive output of females at shallower depths might be a consequence of their larger size. Similarly, King and Butler (1985) in a study focusing on five pandalid shrimp and later Van Dover and Williams (1992) studying 52 species of squat lobsters found that the fecundity was not correlated with depth and the higher reproductive output was a consequence of the individuals larger size. However, in contrast to these results, general patterns of fecundity decreasing with increasing depth have been reported for crustacean (Company and Sardà, 1997 Based on the different fish life-history strategies proposed by Winemiller and Rose (1992), most of the species analyzed in the present study appear to have adopted an intermediate strategy, lying between species with periodic and equilibrium strategies. ...
There is a general hypothesis that species inhabiting deep-sea waters have lower fecundity and larger eggs than shallower species. However, there are few comparative studies which explore this trend because of the complexity of sampling in deep waters, especially in fishes. We present here the first analysis of fecundity and egg size with depth along an isothermal environment. We calculate the relative fecundity and egg size of 11 species of demersal deep-sea fish from the western Mediterranean and included in our analyses published data for an additional 14 species from the same geographic area. The results show that the relative fecundity (eggs per g of individual) of the analyzed fishes slightly decreased along the bathymetric gradient, whereas egg size increased with depth. When the analysis was conducted including only species from the order Gadiformes, the most speciose group in the region and with the widest depth range of distribution (50–2000 m), there was no relationship between relative fecundity and depth, while the deepest species had larger egg sizes than shallower ones. The finding of similar relative fecundities but larger egg sizes suggests that these deep-sea species are investing a higher amount of energy in the production of offspring than shallower water counterparts. The results are discussed in relation to the isothermal characteristics of the deep Mediterranean Sea and ecological adaptations for reproductive success.
... latitudes (Thorson 1936(Thorson , 1950. Evidence also suggests an increase in POI with increasing depth within the oceans (Thorson 1961, 1964, King & Butler 1985, Pond et al. 1997). ...
Within the marine environment, the diverse development modes among marine invertebrate taxa follow a macro-ecological pattern across latitude. Generally, across the latitudinal gradient from the tropics to the poles, larval development becomes increasingly independent of external food resources. Low latitude species are fecund and produce relatively poorly provisioned eggs, which develop into swimming and feeding larvae. This mode of development becomes increasingly scarce with increasing latitude, whilst development from large eggs (produced in low numbers) into larvae, which are non-feeding, becomes increasingly prevalent. From the tropics to the poles, there is an increasing mismatch between the longer periods required for larval development (resulting from increasing cold) and the shorter periods of food availability (resulting from increasing seasonality). This macro-ecological trend in development modes results from the convergent evolution of diverse taxa, which have adapted to high latitude environments in much the same way: through producing larvae which develop independently of external food resources.
Developmental plasticity during the larval phase is a mechanism by which larvae are able to cope better with unfavourable conditions or variations in their environment. Critically, the interaction between per offspring investment (POI; the quantity and quality of resources allocated to offspring) and developmental plasticity, and the role of this interaction in the evolution of larval development modes, is little considered or studied. Experiments comprising this thesis assess the potential role of this interaction in the evolution of abbreviated and lecithotrophic development within decapod crustaceans, and the establishing of the macro-ecological trend in development outlined above.
Experiments used the palaemonine shrimp, Palaemonetes varians, which inhabits temperate, salt marsh, and peripheral brackish water, as a study species. Palaemonine Abstract ii shrimp originated from a tropical marine clade and extant species are found in marine, brackish, and fresh water environments. The evolutionary transition from marine to fresh water has involved life history adaptations in development mode within this group. As species occupy differing habitats along this environmental gradient, this group has been used to study evolutionary adaptations along the environmental gradient from marine to fresh water.
Sampling of a wild population of P. varians from Lymington salt marsh (Hampshire, UK) revealed the highly variable environment that this species inhabits. POI within this population varied inter- and intra-annually, though these variations could not be correlated with variations in environmental temperatures. Larvae hatch with significant yolk reserves and can be considered facultative lecithotrophic in the first and second larval instar, and planktotrophic from the third larval instar. Larval development was successful at temperatures between 15 and 30 °C and temperature-mediated developmental plasticity was observed; at higher temperatures, larvae increasingly developed through fewer larval instars. Development through fewer larval instars resulted in more rapid development, but development to a lesser juvenile dry weight at settlement. Consequently, this developmental plasticity may have ecological implications. Developmental plasticity was also influenced by the energy content of larvae at hatching (as proxy for POI). Larvae with greater energy content developed through fewer larval instars at all temperatures, indicating that higher POI buffers larvae against poor conditions during development. Greater energy content also enabled larvae to tolerate starvation for longer and to develop to more advanced larval stages in the absence of food.
Developmental plasticity within decapod crustaceans enables larvae to tolerate unfavourable conditions during development. Interestingly, it maximises the potential fitness benefits provided by POI by enabling larvae to settle as juveniles earlier, though at a smaller size. The interaction between POI and developmental plasticity forms a ‘pre-adaptation’ for the evolution of abbreviated development. The results presented in this thesis indicate that, indeed, the evolutionary transition to abbreviated development and lecithotrophy is based on selection for increasing POI. The abbreviation of development associated with increasing POI arises through developmental plasticity in larval instar number.
... High latitudes and deep waters are characterized by low temperatures. Therefore in these environments there is a tendency to produce larger eggs reducing fecundity in order to provide the offspring with energy sufficient for a longer developmental time (King and Butler, 1985;MacDonald and Thompson, 1985;Levinton, 1986, 1989;Barber et al., 1988;Mauchline, 1988;Clark and Gore, 1992;Gorny et al., 1992). Conversely, metabolic rates are also reduced and consequently physiological processes demand less utilization of energy. ...
A very important objective of ecological research is to explain the evolution of life histories, more specifically how natural selection modifies reproduction and development in order to generate the patterns that are observed in nature. With few exceptions, the reproductive mechanisms and patterns found in deep-water echinoderms are entirely similar to those found in shallow-water species. The aims of this study were 1) to examine the reproductive biology of the many deep-sea asteroids found on the continental slope to the west of Europe in order to determine if the reproductive adaptations are a function of depth, distribution or are phylogenetically controlled, and 2) to conduct experiments on the effects of pressure and temperature on larval development of Atlantic asteroids, to investigate the physiological potential for deep sea invasion by shallow-water species. Eggs of the shallow-water asteroids Asterias rubens Linnaeus and Marthasterias glacialis (Linnaeus) were fertilized in vitro and incubated through the early embryonic cleavages until the larval stage. They were subjected to different temperature/pressure regimes. Early embryos were able to tolerate pressures up to 150 atm at 15oC and 100 atm at 10oC. Survivorship of A. rubens swimming bipinnaria remained high (> 70%) after incubation at all the pressure/temperature combinations. In M. glacialis the highest survival of swimming larvae was 100% at 1 atm/5, 15 and 20oC and 50 atm/15 and 20oC. Data for the temperature and pressure effects on the later stages of development suggest that all the larval stages are more temperature/pressure tolerant than the early embryos and survivorship becomes greater with larval age. Therefore, the larvae of these two species could survive transport to deeper waters and these species may be capable of sending colonists to the deep sea. In the deep NE Atlantic the habitat has selected for species with specific reproductive traits, which provide them with successful and advantageous life history strategies. This can be clearly observed in the upper bathyal zone between 700 and 1100 m, where the environmental conditions have selected for small species with low fecundity and large eggs, plus habits related directly or indirectly with suspension feeding. These species exhibit reproductive features with trends to the opportunistic strategy and are distinctive of unpredictable environments, although their large egg size probably follows the general trend observed in species from cold waters in order to provide the larvae with energy sufficient for a high survival possibility. Conversely, phylogenetic and evolutionary factors are also important and seem to be decisive at the deepest waters where basically mainly species belonging to the strict deep-sea family Porcellanasteridae are found. All these species possess a mixture of features typical of classical K strategists and equilibrium strategists, which enable them to persist in a relatively stable environment with low energy availability. A comprehensive knowledge of the reproductive processes of the deep-sea fauna is essential in order to evaluate the level of variability caused in the environment principally by human activity and the possible effects on life-history of the species.
... In general, the life history pattern obtained in Madeira archipelago for P. narval was similar to that found in other caridean shrimps. A comparison of von Bertalanffy growth parameters is presented in table 2. (King and Butler, 1985;King, 1987;González et al., 1997;Santana et al., 1997;Company and Sardà, 2000;García-Rodriguez et al., 2000;Colloca, 2002;Maiorano et al., 2002;Chilari et al., 2005). The asymptotic carapace length of males was smaller than that of females and congruent with the maximum captured length of both sexes. ...
Life history traits of Plesionika narval were studied in the Northeastern Atlantic, Madeira archipelago including growth, age, sexual maturity, recruitment pattern and mortality. A total of 28262 specimens were sampled over a period of 8 years comprising two time series from 1991 to 1995 and 2004 to 2008. The relative growth pattern showed a negative allometric nature of growth for combined sexes, males, females, non ovigerous and ovigerous females. Estimated asymptotic carapace length (CL∞) and growth coefficient (K) showed higher values in females (CL∞=30.21 mm, K=0.450 year-1) comparatively to males (CL∞=28.61 mm, K=0.430 year-1), resulting in better overall growth performance in females. The maximum life span (tmax) was estimated at 6.81 years for combined sexes, 6.97 for males and 6.66 for females, however 99.95% of the individuals were younger than 3 years. Although a seasonal spawning season was evident from late summer to late autumn, reproduction may be prolonged throughout the year since ovigerous females are present in all months and achieving sexual maturity at 14.61 mm. The recruitment pattern was continuous throughout the year with a major peak occurring in spring. The total mortality (Z) and fishing mortality (F) were higher in females than in males while natural mortality (M) was similar between groups. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey.
... A decapod's reproductive output (RO) is considered to be one of the most important aspects of its life history pattern (Torres et al., 2007). Interspecific comparisons of RO have provided much of the basis for theoretical considerations of life history strategies (Clarke, 1979;Hines, 1982;King & Butler, 1985;Torres et al., 2007), and intraspecific variations in RO are considered a prominent population characteristic of decapods (Torres et al., 2007). ...
Reproduction and growth of the spiny lebbeid shrimp, Lebbeus groenlandicus (Fabricius, 1775), were investigated based on samples in the East Sea of Korea [= Sea of Japan], from January 2012 to April 2013. We collected 2964 shrimp samples during the study period, which included significantly more females than males (male : female ratio, 1.0 : 1.17). The females were generally larger than the males, and significant differences in the linear-regression slopes of carapace length (CL) versus body weight between the sexes indicate sex-specific differences in allometric growth. The gonadosomatic index (GSI) varied monthly, reaching a maximum in November 2012 (10.28) and a minimum in March 2013 (2.15). The proportion of ovigerous females varied from month to month. The highest values of the GSI coincided with the breeding period, and there was a significant difference between the mean GSI of females with non-eyed and those with eyed eggs, indicating that L. groenlandicus is a consecutive breeder. There was a significant correlation between CL and the number of eggs (EN) in the early egg stages. There was also a significant difference in the slopes of the regressions of CL versus EN between females carrying non-eyed and eyed egg stages. Based on the dry weights in the early egg stages, reproductive output was determined to be 0.18 ± 0.006. The Von Bertalanffy growth function parameters were CL∞ = 38.80 mm, K=0.48 year−1, C=0.5, and WP = 0.4 for males, and CL∞ = 43.64 mm, K=0.41 year−1, C=0.6, and WP = 0.6 for females. The growth performance index (φ′) was 2.86 for males and 2.89 for females.
... The CL of Aristeus antennatus off Mozambique increased over a depth interval of 300 m, but no change was observed for Aristeus virilis (Sobrino et al. 2009). King and Butler (1985) proposed that adult caridean prawns attain larger sizes at greater depths, because lower predation in deeper waters would theoretically allow for a longer lifespan. We could not test this hypothesis on H. triarthrus because no samples were available from trawled depths >500 m. ...
The deep-water trawl fishery along the KwaZulu-Natal coast of South Africa targets several crustacean species, with the knife (or pink) prawn Haliporoides triarthrus contributing most of the catch. Logbook data of fishing effort and catch between 1988 and 2010 were used to assess the distribution and abundance of H. triarthrus on fishing grounds. Generalised linear models were used to quantify the effects of year, month and depth on catch rates. Standardised trends indicated a general decline in abundance between 1990 and 1998, followed by an increase between 2001 and 2008. Catch rates peaked in March, and they were highest between 200 and 499 m depth. Biological samples collected during commercial fishing were used to assess size and sex composition, growth rates and reproductive activity of H. triarthrus. Females became larger than males and mean carapace length (CL) varied by month. The youngest female cohort appeared in November (modal CL of 25 mm), and dissipated after two years (39 mm). Sex ratios were equal for all data combined, but fluctuated by month and CL. Few reproductively active females were recorded. Length-based methods and the standard von Bertalanffy growth function were used to estimate growth parameters (L∞ and K) of females (40.6 mm CL and 1.06 y–1) and males (35.2 mm and 1.27 y–1) respectively. Our findings were compared with information on H. triarthrus from Mozambican waters.
... At the inter-specific level, macro-ecological trends in POI (and its related development modes) are known for marine invertebrates (including marine arthropods); Danish ecologist Gunnar Thorson first observed higher POI in species from higher/polar (cooler) latitudes relative to closely related species from lower/temperate (warmer) latitudes (Thorson 1936(Thorson , 1950. Evidence also suggests an increase in POI with increasing depth within the oceans (Thorson 1961, 1964, King & Butler 1985, Pond et al. 1997). Based on observed trends in POI and knowl - edge of the relationship between POI and develop- ment mode, Thorson (1936Thorson ( , 1950 hypothesised that aplanktonic and planktonic non-feeding (lecitho - trophic) larval development were more prevalent at high latitudes, whilst planktonic feeding (plankto - trophic) larval development was more prevalent at lower latitudes. ...
At the inter-specific level, per offspring investment (POI) is associated with larval development mode and follows a macro-ecological trend within the marine environment; higher POI and its associated greater degree of endotrophy and abbreviated development is found in cooler, high latitude regions. Here, the implications of between-brood-variation in hatchling energy content (measured as carbon mass) on larval starvation resistance and developmental plasticity within the caridean shrimp Palaemonetes varians were assessed. Results demonstrate that greater POI provides increased endotrophy and the potential for abbreviated development. In the absence of food, P. varians larvae from broods of higher hatchling energy content developed to more advanced larval stages and survived for longer before succumbing to starvation. In the presence of food, P. varians larvae from broods of higher hatchling energy content developed through fewer larval instars, showed higher growth rates, and had shorter development times. Also, for larvae developing through the same number of larval instars, larvae from broods of higher hatchling energy content developed to greater juvenile dry weight. These data support the hypothesis that macro-ecological trends in development mode are driven by inter-specific variations in POI. At the intra-specific level, phenotypic plasticity allows for environmentally mediated variations in POI. Under differential selection pressures, this flexibility may, thus, eventually permit the evolution of the diverse and complex life cycles observed in the marine environment.
... The subroutine FISHPARM of the Fisheries Science Application System (FSAS) program (Saila et al., 1988) was used for data processing in the case of Gompertz's function. The mean size (CL) on reaching sexual maturity in females was calculated, defined as the size at which 25% of the total population is ovigerous (King & Butler, 1985). ...
The biology of Plesionika narval (Fabricius, 1787) (Crustacea, Decapoda, Pandalidae) around the Canary Islands (Eastern Central Atlantic) was studied, based on a total of 41679 shrimps of size range 2–30 mm carapace length (CL) collected over a 20-year period. This species carries out seasonal migrations; shrimps concentrate in deep waters in the autumn, move to shallower waters during winter and spring, and return to deep waters in summer. The growth parameters of males were L0nfin;=29·47mm CL and k=0·54 year−1, and of females were L0nfin;=31·90mm CL and k=0·66 year−1, with size generally increasing gradually with depth. Carapace length/wet weight relationships showed negative allometry. Ovigerous females occur year round but a spawning peak was determined from April to June when the population is found in shallower waters (26–175 m). Ovigerous females decrease in number as the depth increases. The size at maturity in females was 11·96mm CL. The study of the sex ratio by depth and the seasonal migrations, as well as the sex differences in growth, confirm that this species conforms to the reproductive pattern of tropical pandalids, in which dioecy occurs.
Abstract
The feeding ecology of deep-sea crustaceans is crucial in understanding the ecological roles and interactions of deep-sea organisms as they play a critical role in deep-sea food webs as intermediate trophic level organisms. This study provides the first examination of the feeding ecology of deep-sea shrimp Plesionika semilaevis (Spence Bate 1888) and provides new insights into deep-sea community structure. An aggregate number of 2213 individuals (842 males, 1016 berried and 355 non-berried females) were collected from the South Eastern Arabian Sea from 2019 to 2022 and their feeding ecology was studied in relation to the environmental (season) and biological (maturity, sex and size) factors. The index of preponderance values indicates the species has a diversified diet with a wide trophic niche ranging from smaller foraminifera to larger crustaceans and fishes. Frequency of occurrence (FOC) reveals that crustaceans, detritus and foraminifera forms the main prey while fishes, molluscs and sponges form the secondary prey. Berried females had the highest feeding intensity compared to males and non-berried females. Among the studied groups,the percentage of full stomachs was higher during the pre-monsoon period than post-monsoon. Feeding intensity was highest for smaller individuals and decreased gradually with an increase in size. Statistical analyses (ANOVA) also confirmed the significant differences (p<0.05) in the diet composition and feeding intensity of berried and non-berried females, pre-monsoon and post-monsoon samples and, juveniles and adults. The PERMANOVA test showed that there were significant differences in diet in the interaction between sex and size (p=0.003) and between sex and season (p=0.001). The present study also suggests that the seasonal variation in feeding intensity could be attributed to oceanographic phenomena like upwelling prevailing in the South Eastern Arabian Sea.
Keywords: Crustaceans, Deep-sea ecology, Feeding behaviour, Prey selection, Upwelling
Biological trait analysis has become a popular tool to infer the vulnerability of benthic species to trawling-induced disturbance. Approaches using multiple traits are being developed, but their generic relevance across faunal components and geographic locations remains poorly tested, and the importance of confounding effects are poorly recognised. This study integrates biological traits of benthic species that are responsive to instantaneous effects of trawling (i.e. sensitivity) and traits expressing recoverability over the longer term (i.e. years). We highlight the functional independence between these 2 components in response to trawling, test the behaviours of single and combined traits and account for potential confounding effects of environment and trawling intensity on benthic communities through variation partitioning. Two case studies are considered: epibenthos from the Bay of Biscay and endobenthos of the Dutch sector of the North Sea. The response to trawling is most pronounced when multiple traits covering different aspects that determine population dynamics (i.e. sensitivity and recoverability) are combined, despite confounding effects between gradients of benthic production and trawling intensity, especially for endobenthos. The integration of traits reflecting both sensitivity and recoverability provides complementary information on the faunal response to trawling, bridging the gap between fishing impact assessments and benthic community status assessments.
Two species of the deep-water Caridea genus Nematocarcinus occurring in western Mexico were studied: N. faxoni (1463 specimens) and N. agassizii (169 specimens). All samples considered, N. faxoni, were represented by 35% of males, 59% of females, and only 6% of ovigerous females, the latter occurring throughout the seasons; in the case of N. agassizii, ovigerous females represented 29%. In N. faxoni, size at first maturity was 16.95 mm carapace length. The number of eggs in N. faxoni varied from 1269 to 6882 (average, 3700), and the relationship between ovigerous female size and number of eggs was moderately good. Egg size in N. faxoni (0.50 mm to 0.80 mm long axis; 0.40 mm to 0.69 mm short axis) did not vary with female size.
This study quantified the effects of temperature on reproduction and maternal provisioning of the ectoparasite, Neobenedenia girellae (Platyhelminthes: Monogenea), a species known to cause detrimental impacts to aquaculture fishes in tropical and subtropical environments worldwide. At 20 and 25 °C, parasites exhibited relatively slower production of larger eggs that were energy-dense. In contrast, parasites at 30 °C attained sexual maturity faster, were reproductively active over a shorter period, grew to a smaller size and laid smaller, less energy-rich eggs at a faster rate. As such, parasites exhibited two distinct reproductive patterns in response to temperature: parasites at lower temperatures produced larger eggs with higher energy content, while those at the higher temperature had a higher rate of egg production. Larger eggs produced under cooler conditions were better provisioned with energetic reserves and important, membrane-bound lipids that would likely facilitate larval longevity and development success. This is commensurate with previous observations of epizootics of this parasite species in aquaculture systems during winter. Meanwhile, eggs produced at 30 °C contained higher proportions of saturated fatty acids compared with polyunsaturated fatty acids, likely reflecting metabolic regulation of cell membrane fluidity, which is necessary for larvae to survive warm conditions. This study demonstrates that fish ectoparasites have evolved substantial reproductive and metabolic flexibility to maximise infection success under variable environmental conditions.
Plesionika narval is a widespread species of the Pandalidae family, of particular high economic importance for small-scale shrimp trap fisheries in the Dodecanese Islands (SE Aegean Sea). Understanding its biology and reproduction are crucial for stock management. Reproductive biology aspects were studied through data collected during monthly experimental surveys with baited shrimps traps from November 2014 to October 2015 at a depth range of 10 - 150m. A total of 3436 individuals within the size range of 6.46 to 20.20 mm carapace length (CL) was analyzed. Overall, mean female size was significantly higher than mean male size, while the mean size of ovigerous females was higher than that of non-ovigerous females. Mean carapace length of ovigerous and non-ovigerous females was significantly correlated to depth. Ovigerous females were observed throughout the study period; however, monthly proportions revealed April to October as the main reproductive period of the species in the area. The sex ratio showed a clear predominance of females in the shallow depth zone (10-25 m) and was found to be affected by sampling area and depth zone. Immature females were found from November to March. Mature females were found all year round, exhibiting higher percentages in March, June, July and September, coinciding with the main reproductive period. P. narval seemed to spawn more than one time within the annual reproductive cycle. Gonadosomatic index obtained its highest mean values in May, June and September, thus revealing the main reproductive period. Size at first maturity for females was estimated at CL50=11.7 mm.
Parapenaeus fissuroides Crosnier, 1985 is an emergent fisheries shrimp resource in the benthic community of Kagoshima Bay. The growth pattern and longevity of P. fissuroides were estimated from monthly length-frequency distributions. Carapace length (CL) ranged from 7.7-27.1 mm in males and 6.4-36.1 mm in females. Both males and females were recruited during late autumn and winter. Growth was best described by Pauly &Gaschütz's growth equation as Lt = 25.6(1-exp(-1.011(t/12 + 0.539)-(0.641/2π) sin(2π(t/12-0.577)))) for males and Lt = 34.3(1-exp(-0.941(t/12 + 0.227)-(0.581/2π) sin(2π(t/12-0.603)))) for females. Females grew faster and reached larger sizes than males of the same age group. The life-span of P. fissuroides was estimated to be around 2 years for males and 2.5 years for females.
We investigated the fecundity, egg size, reproductive output, and breeding frequency and season of Neocaridina denticulata denticulata and Latreutes planirostris which inhabit extremely different habitats. The marine shrimp Latreutes planirostris produced more eggs had at a given carapace length than the freshwater shrimp N. d. denticulata. However, N. d. denticulata had a larger egg volume and greater reproductive output than L. planirostris. The monthly gonadosomatic index (GSI) of the freshwater shrimp began to increase in April and reached a maximum in May, suggesting a single breeding period. In contrast, the GSI of the marine shrimp exhibited two breeding peaks: May-June and September. In both shrimps, the regressions between carapace length and ovarian weight were significant at the non-eyed and eyed embryo stages. For both species, an analysis of covariance revealed significant difference between the two regressions in elevation, but not in slope. These results indicate the potential for multiple ovulations within the reproductive season.
In this study, we investigated the distribution patterns of two crangonid shrimps in the East Sea of Korea. The distributions of the shrimps differed significantly with depth. Neocrangon communis (Rathbun, 1899) was found at depths of 300-900 m throughout the survey area, with the greatest number of individuals at 300 m depth in the total sampling period. Argis toyamaensis (Yokoya, 1933) occurred over the entire depth range (300-900 m), with the greatest numbers of individuals at 800 m depth in the total sampling period. On average, the large females and ovigerous females of N. communis and A. toyamaensis were mainly distributed in shallow waters (300-400 m depth). The ovigerous females of the shallow-dwelling species N. communis mainly occurred in shallow waters. The deep-dwelling species, A. toyamaensis, differed slightly from N. communis in terms of the distribution of its ovigerous females. The ovigerous females of A. toyamaensis were widely distributed at all depths, and the gonadosomatic index did not differ significantly with depth. However, the deep-dwelling species, A. toyamaensis, had larger eggs than had N. communis. We suggest that life-history strategies are determined by many environmental factors, including depth, in the deep-water environment. The optimal distribution depths of these two species were closely related to their reproductive strategies.
The pandalid Plesionika izumiae Omori, 1971 is widely distributed in the west Pacific regions. This is a relatively common shrimp in the coastal waters of Japan, except off northern Honshu and Hokkaido, and is commercially important for small-scale bottom seine fishery. The growth patterns and longevity of P. izumiae were estimated in Kagoshima Bay, southern Japan, using time series of the length-frequency distributions during February 2007 to January 2011. Carapace length ranged from 4.4-14.5 mm in males and 4.0-14.7 mm in females. Both males and females were first recruited in autumn (October-November) with modal size around 7.0 mm carapace length. The growth was best described by the Pauly and Gaschütz equation as L t =11.95[1 – exp{-3.991(t/12 -0.118) - (2.866/2π) sin(2π(t/12 - 0.955))}] for males and L t =12.73[1 - exp{-4.084(t/12 -0.142) - (2.646/2π) sin(2π(t/12 - 0.912))}] for females. Females grew faster and reached a larger size at the same age than males. Monthly growth rate was lower during December to February and higher during March to May in both sexes. The longevity of this species was estimated to be around 18 months for both sexes. The relationship between carapace length and body weight indicated negative allometric growth in males and positive allometric growth in females.
Eualus biunguis was found at depths of 500-900 m in the East Sea of Korea, with the highest percentage of occurrence (33%) at 800 m. A positive correlation was observed between the number of individuals and depth. The overall sex ratio with depth deviated significantly from the expected 1 : 1, with a predominance of females, ranging from 84.80% to 97.25%. On average, the large males occurred at 600 m, the large females and ovigerous females were found at 800 m. Only non-ovigerous female E. biunguis were parasitized by the bopyrid isopod, Hemiarthrus abdominalis on the abdominal sternum between the first and second pleopods. The number of infested females differed significantly with depth. The relationship between carapace length and body weight in the parasitized and non-parasitized shrimps differed significantly, and the intercept of the non-infested shrimps was higher than that of the infested shrimps. This finding indicates that the parasite H. abdominalis has a negative effect on the growth of E. biunguis. Not only were the ovigerous females observed in relatively shallow depth range of the water, but their distribution depth range was extended to 900 m. The ovary weight of ovigerous E. biunguis increased during the incubation period, suggesting that the females are consecutive breeders, capable of multiple spawning within a single reproductive period. The gonadosomatic indices of the nonovigerous females and ovigerous females differed significantly with depth. Mean egg size was 0.71 ± 0.09 mm3 in the non-eyed stage and 0.89 ± 0.16 mm3 in the eyed stage. There was no significant relationship between carapace length and egg size in the deep-water dwelling species E. biunguis.
Three species of the callianassid genus Nihonotrypaea occur in the Ariake Sound estuarine system, southern Japan; they consist of two tidal-flat species (N.harmandi; N.japonica) and one boulder-beach species (N.petalura), with maximum population densities of 1440, 343, and 12 ind m−2, respectively. Nihonotrypaeaharmandi and N.petalura are distributed along the coastline from the outermost part of the sound to the open sea, while N.japonica occurs in the middle part of the sound. Nihonotrypaeajaponica has an extended reproductive period from late winter to autumn, while those of the other species are from late spring or summer to autumn. Interspecific comparisons were made for recently laid egg size (as volume) and clutch size (as number of eggs per female). Only in N.japonica was a seasonal egg size variation observed, being significantly larger in winter to spring (mean=0.106 mm3) than in summer (0.080 mm3). By contrast, clutch size was significantly smaller in winter to spring, resulting in nearly the same clutch volume per female (product of the mean egg volume and clutch size) between the seasons. Among the three species, the egg size was ordered as N.japonica (overall mean volume through the seasons=0.092 mm3)>>N.petalura (0.057 mm3)>N.harmandi (0.054 mm3). The clutch size was ordered as N.harmandi>N.petalura[approximate]N.japonica. The clutch volume was ordered as N.japonica[approximate]N.harmandi>N.petalura. The smallest clutch volume value for N.petalura female showed an opposite trend to the relative size of the major cheliped found in a previous study.
The distribution and population structure of the deep-water pandalid shrimp Plesionika semilaevis were studied by experimental sampling surveys at 8 stations in Kagoshima Bay, southern Japan, from May 2003 to January 2007. A simple trawl net measuring 27.9 mm and 20.2 mm mesh size at the net body and cod end respectively was used. All individuals belonging to pisces, crustaceans (Decapoda, Stomatopoda, Mysidacea and Euphausiacea) and molluscs (Cephalopoda, Bivalvia and Gastropoda) were sorted at each haul and identified to species level, then counted and weighed in the laboratory. P. semilaevis was the most dominant species by number and weight of individuals collected in the current survey. Further, 98% of the individuals of P. semilaevis occurred at Stations 4 and 5 (180 m and 220 m depth respectively) located in the deepest part of the central bay, all year round. However, significant differences were observed in sex ratio and body size composition of P. semilaevis from these two stations. In Kagoshima Bay, the spawning and hatching grounds of P. semilaevis were estimated to cover the entire areas of its distribution.
Cymonomus menziesi Garth, 1971 is cited by first time to Chile. The specimens were caught during a survey on board of R/V "Sonne", the material was derived from project on benthic communities in the oxygen minimum zone along the Chilean coast line. The specimens were obtained from one station at 500 m depth off Chiloe. The female specimen of this species is described, and the preliminary aspects about its biology are showed. The presence of this species in southernmost 30 latitudinal degrees from the original report is discussed here.
Different features of reproduction (breeding periods, number of generations per year, clutches per generation, clutch sizes, egg sizes) were studied in five species of Gammarus in the Baltic Sea and in the Limfjord, Denmark and in two species at localities along the west coast of the European continent. Breeding periods, numbers of annual generations (one or two), and number of clutches per generation show some geographical variation within each species; this is explained by interspecific relations (reproductive character displacement) in conjunction with local water temperature. Winter breeding forms have fewer and larger eggs than summer breeding forms; this is explained as an evolutionary adaptation to a larger juvenile mortality resulting from a low growth rate at low temperatures. Reproductive effort (total egg volume per clutch) is nearly identical for four of the species within each area, but differs between areas. No explanation for this effect is attempted; it is pointed out that considerations on r- and K-selection are futile for understanding such data. This will require much more detailed data on age specific mortality in nature under different environmental conditions than is normally available for invertebrate populations. /// Различие особенности размножения (периоды размножения, количество поколений в год, количество кладок в одном поколении, величина кладки, размеры яиц) исследовали у 5 видов гаммаруса в Балтийском море и а Лимфьорде (Дания) и у 2-х видов в местообитаниях у западного побережья Европы. Периоды размножения, количество поколений в год (1 или 2) и числокладок на генерацию имели некоторые географические различия у представителей каждого вида; это объясняется межвидовыми отношениями (смещение репродуктивных признаков) вместе с влиянием локальных температурных условий воды. формы, размножающиеся зимой, имеют меньше яиц и более крупные их размеры, чем формы, размножающиеся летом. Это объясняется как эволюционная адаптация к более высокой смертности молоци в результате низкой скорости роста при низкой температуре. Репродуктивные показатели (общий объем яиц на кладку) почти идентичны у 4 видов в пределах каждого местообитания, но различаются в разных типах местообитаний. Эта особенность не объяснена; отмечено, что привлечение r- и К-стратегии неэффективно для понимания этих особенностей. Это потребует более детального определения смертности в разных возрастах в условиях различных природных местообитаний, чем это обычно делается при изучении популяций беспозвоночных.
In this paper I explore two lines of thought. First, do life-history tactics exist at the intra-specific level? Four arguments are examined: (1) biological constraints violate the assumptions of the Euler-Lotka equation; (2) experimental evidence on mosquito fish indicates that physiological problems can overwhelm the expected coadaptations of life-history traits; (3) the pattern of heritabilities of life-history traits indicates that they have not responded to the same selection forces; (4) authors of review articles perceive tactics more readily at higher taxonomic levels than within species. Tactics may not exist in the expected form. Second, when might optimality models work, and why? (1) Some optimality models contain a hidden genetic component; (2) polygenic traits are not as tightly constrained as few-locus systems; and (3) the evolution of the developmental system should uncouple the phenotype from the constraints of the genetic mechanism. Implicit in these thoughts is a more general point: training in quantitative genetics, development, and physiology is just as necessary for the study of life-history evolution as is training in demography and population genetics. Finally, four new research programs are suggested as extensions and criticisms of the arguments raised here. /// В данной стаье я развиваю мысль в двух направлениях. Во-первых, сущест-вует ли тактика жизненного цикла на интравидовом уровне? Проведены 4 аргумента: 1. биологическая напряженность нарушает взаимосвязи, описан-ные уравнением Эйлера-Лотки; 2. эксперименты, проведенные на гамбузии, показали, что физиологические проблемы могут перекрывать предполагае-мые коадаптации онтогенеза; 3. характер наследственных особенностей онотогенеза показывает, сто они не связаны с такими же направлениями от-бора; 4.3 авторы обзорных статей чаще рассматривали тактические особен-ности на высших таксономических уровнях, чем внутри вида. Тактические особенности имеют неожиданную форму. Во-вторых, когда должны действовать оптимальные модели и почему? 1. некоторые оптимальные модели имеют скрытый генетический компонент; 2. политенные особенности не так сильно появляются, как малолокусные системы; и 3. эволюция развивающейся системы отключает фенотип от прес-са генетического механизма. Неясно выражено в этих рассуждениях более общее положение: привлече-ние данных по количественной генетике, развитию и физиологии таюке необходимы для изучения эволюции онтогенеза, как и исследования демо-графии и генетики популяции. В конце рассматриваются 4 новые исследо-вательские программы как продолжение и критика приводимых здесь аргу-ментов.
Females of the speckled wood butterfly lay eggs that decrease in size over the oviposition period. By weighing all of the individual eggs laid by 2 females and rearing the larvae from these eggs individually the authors assessed whether there was any correlation between egg weight and egg survival, larval survival, larval development time and pupal weight. None of these fitness variables was correlated with egg weight. Since females could have increased their fecundity by c25% if they had laid small eggs only, this result raises the question of what factor can be responsible for counteracting the maximization of the number of eggs laid. Time is a limiting factor for ovipositing butterflies, and it is well known that butterfly females devote considerable time to locating suitable habitats and host plants for the deposition of their eggs. Butterfly females may thus trade-off between maximizing number of eggs laid and time spent searching for suitable oviposition sites for each individual egg.-from Authors
Many benthic marine invertebrate species have mixed life histories, in which larvae emerge into the plankton to continue their development after a relatively short period of encapsulation. In such cases, the benefits of encapsulation are not obvious and are considered here. A simple probability argument is constructed which suggests that even a short period of encapsulation can significantly reduce mortality during mixed development if daily mortality rates in the plankton are below some critical level. Survival benefits of even short periods of encapsulation would be augmented further if free-living larvae were less susceptible to mortality than were free-living embryos. Encapsulation may reduce developmental mortality in mixed life cycles simply by retaining developmental stages until they are better able to avoid planktonic and benthic predation.
The empirical study of life history patterns has revealed a complex of interrelated adaptations that cannot easily be explained by reference to the models of demographers. Parental investment can be expended in many ways by manipulating propagule size, propagule number, and the pattern of propagule dispersal in time and space. Each aspect of reproduction entails a balance between the benefits and cost of current reproduction versus future reproduction. Natural selection results in the pattern of reproduction that maximizes the lifetime contribution of an individual to future generations. The compromise between propagule size and propagule number is modeled by the effects of competitive challenges during the early juvenile period, dispersal mechanisms, and mechanisms of predator defense. The position of the balance is modeled by the interaction of the level of investment per clutch and the functional dependence of early juvenile survival on propagule size. The spatial pattern of egg deposition is modeled b...
The relationship of the demographic parameters of a population to its ecological niche constitutes one of the central problems of population biology. A most interesting theoretical notion pertinent to this problem is r- and K-selection (MacArthur 1962; Cody 1966; MacArthur and Wilson 1967; Hairston, Tinkle, and Wilbur 1970; Roughgarden 1971). The central idea of r- and K-selection is that populations living in environments imposing high density-independent (D.I.) mortality (r-strategists) will be selectively favored to allocate a greater proportion of resources to reproductive activities at the cost of their capabilities to propagate under crowded conditions, and conversely, populations living in environments imposing high density-dependent (D.D.) regulation (K-strategists) will be selectively favored to allocate a greater proportion of resources to nonreproductive activities, at the cost of their capabilities to propagate under conditions of high D.I. mortality. From the argument just stated, it may be deduced that the birth rate of an r-strategist will be greater than that of a related K-strategist. However, increased birth rate under conditions of high D.I. mortality is not sufficient evidence for an r-strategy, because, as demonstrated later in this paper, any increase in D.I. mortality must by itself produce a new equilibrium of birth and death rates at higher values of both. The crucial evidence needed for r- and K-selection is whether an organism is allocating a greater proportion of its resources to reproductive activities (r-strategists) than another related one (K-strategist) under any and all D.D. and D.I. mortality conditions.
The tremendous variation in the life-history patterns of organisms is best explained as adaptive.any organism has a limited amount of resources at its disposal, and these have to be partitioned between reproductive and nonreproductive activities. A larger share of resources to reproductive activities, that is, a higher reproductive effort at any age, leads to a better reproductive performance at that age; this may be considered a as profit function. This reproductive effort also leads to a reduction in survival and growth and consequent diminution of the reproductive contribution of the succeeding stages in the life history; this may be considered as a cost function. Natural selection would tend to an adjustment of the reproductive effort at every age such that the overall fitness of the life history would be maximized. A model of life history processes has been developed on the basis of these considerations. It leads to the following predictions: 1. If the form of the profit function is convex, or that o...
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It is possible to think of organisms as having a certain limited amount of time or energy available for expenditure, and of natural selection as that force which oper- ates in the allocation of this time or energy in a way which maximizes the contribution of a genotype to following generations. This manner of treatment of problems con- cerning the adaptation of phenotypes is called the "Principle of Allocation" (Levins and MacArthur, unpublished), and one of its applications might be the formulation of a general theory to account for clutch size in birds. At this stage we will assume that clutch size is a hereditary phenotypic characteristic which can be affected to a greater or lesser extent by the prevailing environmental conditions and which ex- hibits the normal variability of such char- acteristics. Lack (1954) discusses the validity of several hypotheses which' at- tempt to account for clutch size and its variation under different circumstances and conditions, all of which were rejected in favor of his now widely accepted theory that clutch size is adapted to a limited food supply. This paper is an attempt to show that this and other existing hypotheses when taken singly are inadequate in some respect to account for all the data, that each holds for some particular set of con- ditions, and that each is but a part of the complete explanation. The theories will be dealt with individually and it will be shown that as environment varies so will the fac- tors which determine clutch size. PRESENTATION OF THE THEORY
The hypothesis of antagonistic interactions between life-history characters, generalized to take genetic variability into account, is the most satisfactory theory of life-history evolution available. -from Author
Most examinations of body size center on a single factor. However, because body size is directly or indirectly linked to many, if not most, life history characters a more holistic approach is advocated. In this paper I present such an approach in the analysis of the optimum body size of Drosophila melanogaster. The basic life history parameters determining r are shown to be related to body size. Using these functions the relationship between r and body size is obtained. It is found that r is maximized within the observed range in size. A sensitivity analysis indicates that this result does not depend critically upon parameter estimation. This analysis also indicates that variation in egg size between geographic strains should be positively correlated to variation in body size. This prediction is shown to be correct. Reasonable variation in parameter values can account for much of the size range observed in the genus Drosophila. It does not appear to be possible to account for the very large size of certai...
The cost of reproduction was examined in the predatory rotifer Asplanchna bright-welli. Survivorship and fecundity schedules of 1,774 individuals were determined in a laboratory environment. Analysis of these data revealed reproductive patterns associated with long and short lived individuals. Long lived individuals spent the largest part of their life reproductive, distributed reproduction evenly over many age classes, and reproduced at relatively low rates. In contrast, short lived individuals spent the largest part of life prereproductive, concentrated reproduction in a few age classes, and reproduced at a high rate, producing many offspring late in life. The relationship of age-specific fecundity and lifespan was examined using residual reproductive value and probability of future survival. Regression analysis demonstrated that reproduction in one age class is inversely related to the residual reproductive value of subsequent age classes. Similarly, reproduction in one age class decreases the probability of surviving to the second subsequent age class. These results clearly demonstrate that reproduction is deleterious to future survival.
(1) The annual triclad, Dendrocoelum lacteum, preserved egg capsule output to a greater extent under conditions of nutritive stress than the perennial species, Dugesia lugubris and Polycelis tenuis. (2) Under normal nutritive conditions reproductive effort was higher in Dendrocoelum lacteum than in Polycelis tenuis. As food supply was reduced reproductive effort rose ten-fold in Dendrocoelum lacteum but only three-fold in Polycelis tenuis. (3) There was a direct and significant relationship between adult mortality and the effort put into reproduction in Dendrocoelum lacteum. (4) The hatchlings of D. lacteum were better able to cope with feeding disturbances than those of Polycelis tenuis. (5) It was suggested that differences in the susceptibility of hatchlings to nutritive disturbance may have been instrumental in the evolution of differences in reproductive strategy between species.
The argument that, under the operation of natural selection, the most productive litter-size should necessarily be also the most frequent litter-size is fallacious. The total number of weaned offspring is a combination of two components; the frequency distribution of the different sizes of litter and the number of weaned offspring from each litter-size. Natural selection favours those genotypes that maximize this combination. There is no reason to suppose that the maximum of this combination of two components coincides with the maximum of the single component, the number of weaned offspring per litter.
Quatorze espèces de crevettes Carides et trois espèces de Pénéides ont été capturées dans des nasses au cours de recherches dans les îles sud-ouest-pacifiques de Fidji et Vanuatu (précédemment Nouvelles-Hébrides), Ouest-Samoa et Tonga. Plesionika longirostris, Heterocarpus sibogaeet H. laevigatas ont été habituellement prises dans les quatre îles et une quatrième H. gibbosus, était commune dans les eaux des Fidji. De brèves descriptions et une clef sont fournies. Les taux des captures moyennes maximales étaient, par nasse, de 1,2 kg à Fidji, de 2,8 kg à Vanuatu, et de 1,4 kg a Ouest-Samoa, à des profondeurs de 500-600 m. A Tonga le taux maximal de prises des grandes espèces à’Heterocarpus se situait par plus de 700 m. Les variations des taux de captures dans le temps et des tailles des crevettes avec la profondeur suggèrent qu’il existe des migrations cycliques pour certaines espèces.
[Das Verbreitungsareal von Emerita analoga (Stimpson) wird im Norden bis Karluk, Kodiak Island, Alaska und im Süden bis zur False Bay, Argentinien, erweitert. Die Eigröße nimmt während der Entwicklung zu und verändert sich mit der geographischen Breite. Die größten Eier wurden bei 45° N und 35° S gefunden; das Eivolumen nahm sowohl nördlich als auch südlich dieser Regionen ab. In den Tropen kommt Emerita rathbunae Schmitt vor; diese Art besitzt sehr kleine Eier. Es wird angenommen, daß die Temperatur das Eivolumen bestimmt und daß die entsprechende Optimal-temperatur 11° bis 13°C ist. Eine ähnliche Annahme wird für Balanus balanoides L. gemacht, und zwar auf Grund publizierter Daten. Eine lineare Beziehung zwischen Eizahl pro Weibchen und Carapax-Länge bei Emerita analoga ist unabhängig von geographischer Breite und Temperatur. Es wird vermutet, daß das Eivolumen mit abnehmender Temperatur zunimmt, weil die Zoea-Larven mehr Nahrung benötigen, um die längere planktonische Entwicklungsphase zu überleben., Das Verbreitungsareal von Emerita analoga (Stimpson) wird im Norden bis Karluk, Kodiak Island, Alaska und im Süden bis zur False Bay, Argentinien, erweitert. Die Eigröße nimmt während der Entwicklung zu und verändert sich mit der geographischen Breite. Die größten Eier wurden bei 45° N und 35° S gefunden; das Eivolumen nahm sowohl nördlich als auch südlich dieser Regionen ab. In den Tropen kommt Emerita rathbunae Schmitt vor; diese Art besitzt sehr kleine Eier. Es wird angenommen, daß die Temperatur das Eivolumen bestimmt und daß die entsprechende Optimal-temperatur 11° bis 13°C ist. Eine ähnliche Annahme wird für Balanus balanoides L. gemacht, und zwar auf Grund publizierter Daten. Eine lineare Beziehung zwischen Eizahl pro Weibchen und Carapax-Länge bei Emerita analoga ist unabhängig von geographischer Breite und Temperatur. Es wird vermutet, daß das Eivolumen mit abnehmender Temperatur zunimmt, weil die Zoea-Larven mehr Nahrung benötigen, um die längere planktonische Entwicklungsphase zu überleben.]
In order to assess current scientific understanding of life-history evolution, the alternative fundamental theories are formulated in a refutable form and compared with the available empirical evidence. The hypothesis that life-history does not evolve is rejected on the grounds that life-history can be readily modified by artifical selection. The hypothesis that life-history evolves according to mechanisms other than natural selection acting on genetic variation is shown to have no sound experimental basis. The hypothesis that life-history evolution depends primarily on group selection is undermined by the absence of the predicted group adaptations. The hypothesis that life-history is a unitary character which evolves in the same fashion as fitness is rejected because of the disparity between life-history genetics and basic theory concerning the evolution of fitness. The hypothesis that life-history is composed of a set of autonomous characters which are subject to mutation accumulation at later ages is refuted by the lack of any detectable increase in genetic variability with age and the evidence for the interdependence of life-history characters. It is concluded that the hypothesis of antagonistic interactions between life-history characters, generalized to take genetic variability into account, is the most satisfactory theory of life-history evolution available.
The principle of allocation of time and energy is used to formulate a general theory to account for clutch size in birds. "Advantages" are figured as the axes of a three-dimensional graph, and phenotypes allocating their energy in particular ways as points in space forming a surface and enclosed solid. In the temperate zones most energy is used to increase the reproductive rate r. In the tropics the carrying capacity of the habitat is more important, resulting in a smaller clutch size. Different phenotypes will be more fit in different environments, as optimum allocation of energy differs. Previous theories of clutch size are discussed, and incorporated into this general theory. Increase of clutch size with latitude is analyzed, and accounted for by the theory. Predictions are made that all stable environments, the tropics, islands, coasts, will favor reduced clutches. Examples are quoted in which instability of conditions results in increased clutch size. The situation of predation-free species is examined, and it is predicted that the clutch size of such species will remain relatively unchanged with latitude changes. These predictions seem to be verified in all cases where data are available to test them.
Morphometric studies were carried out as part of resource assessment surveys on deepwater pandalid shrimps in both the northern and southern tropical Pacific Ocean. Previous works have suggested that pandalid shrimps, including those of some tropical species, are typically protandrous hermaphrodites. In this study, however, measurements of certain male secondary sexual characteristics were positively correlated with shrimp size. There was no evidence of degeneration of these characteristics in larger individuals as would be expected with protandrous hermaphrodites. We conclude that shrimps of the tropical pandalid species examined are dioecious and that sex reversal does not occur.
PLANKTONIC larvae are dispersal stages which make it possible for marine
species to breach faunal barriers and to colonize new regions. The
occurrence of trans-oceanic dispersal by larvae of the shoal-water
tropical benthos can be deduced if the actual distribution of such
larvae is known relative to the principal ocean currents likely to
transport them.
The population structure and reproductive biology of the burrowing mud crab Helice crassa Dana, 1851 were studied in relation to latitude. Populations from 11 sites in New Zealand between latitudes of 35° South (lowest) and 46°27′ South (highest) were sampled during November and December 1980. Crab densities (crabs·m−2) were correlated significantly with latitude and were higher at low than high latitudes. In general, population size structures were similar, and each population had few large individuals (carapace width > 14.0 mm), an unbiased sex ratio and a size-frequency distribution skewed in favor of juvenile and small crabs (carapace width ≤ 6.0 mm). However, maximum crab size, size of maturity of females, and numbers of eggs carried per female increased significantly with increased latitude. Volumes and dry weights of eggs differed significantly between populations, but independently of latitude. Nevertheless, percentage swelling of eggs during embryonic development did increase significantly from low to high latitudes. The data are discussed in relation to general trends and hypotheses proposed currently for latitudinal effects on marine invertebrate populations.
An examination is made of the body sizes of species of euphasiidss, mysids, copepods and chaetognaths living in different bathymetric zones. The maximum body size of each species is used as a measure of its potential for growth in size. Bathypelagic euphausiids and mysids are shown to possess a much greater potential for attaining greater size than corresponding epipelagic species. Body size of copepods shows a potential increase down to depths of 1000–2000 m but, thereafter, there is a decrease in the potential size. Mesopelagic and bathypelagic chaetognaths are potentially larger than most epipelagic species.
Summary1. In analysing the ecological conditions of an animal population we have above all to focus our attention upon the most sensitive stages within the life cycle of the animal, that is, the period of breeding and larval development.2. Most animal populations on the sea bottom maintain the qualitatively composition of the species composing them, over long periods of time, though the individual species use quite different modes of reproduction and development. This shows that species producing a large number of eggs have a larger wastage of eggs and larvae than those with only a few eggs. The wastage of eggs in the sea is much larger than on the land and in fresh water.3. In the invertebrate populations on the level sea bottom, large fluctuations in numbers from year to year indicate species with a long pelagic larval life, while a more or less constant occurrence indicates species with a very short pelagic life or a non-pelagic development.4. In most marine invertebrates which shed their eggs and sperm freely in the water, either (a) the males are the first to spawn, thus stimulating the females to shed their eggs, or (b) an ‘epidemic spawning’ of a whole population takes place within a few hours. Both methods greatly favour the possibility of fertilization of the eggs spawned and show that the heavy wastage of eggs and larvae takes place after fertilization, during the free swimming pelagic life.5. Embryos with a non-pelagic development may originate (a) from large yolky eggs, in which case all the hatching young of the same species will be at the same stage of development, or (b) from small eggs which during their development feed on nurse eggs, when the individual embryos of the same species may vary enormously in size at the stage of hatching.6. Three types of pelagic larvae are known: (a) Lecithotrophic larvae, originating from large yolky eggs spawned in small numbers by the individual mother animals; they are independent of the plankton as a source of food although growing during pelagic life, are absent from high arctic seas but constitute about 1o% of the species with pelagic larvae in all other seas, (b) The planktotrophic larvae with a long pelagic life, originating from small eggs spawned in huge numbers by the individual mother animal; they feed from, and grow in, the plankton, constituting less than 5% of high arctic bottom invertebrates, 55–65% of the species in boreal seas, and 8o-85 % of the tropical species, (c) The planktotrophic larvae with a short pelagic life having the same size and organization at the moment of hatching and at the moment of settling; these constitute about 5% of the species in all Recent seas.7. To find out the factors which cause the enormous waste of eggs and larvae, we thus have to study those forms (constituting 7o% of all species of bottom invertebrates in Recent seas) which have a long planktotrophic pelagic life, as only species reproducing in this way have really large numbers of eggs.8. The food requirements of the planktotrophic pelagic larvae are much greater than those of the adult animals at the bottom. The adaptability of the larvae to poor food conditions seems, nevertheless, to be greater than hitherto believed. The significance of starvation seems mainly to be an indirect one: poor food conditions cause slow growth, prolong larval life, and give the enemies a longer interval of time to attack and eat the larvae.9. At the temperatures to which they are normally exposed, northern as well as tropical larvae seem on an average to spend a similar time (about 3 weeks) in the plankton. The length of the pelagic life of the individual species may, however, vary significantly in nature. In the Sound (Denmark) the larvae are never exposed to temperatures outside the range which they are able to endure. The wastage caused by temperature, like that due to starvation, seems mainly to be an indirect one: low temperatures postpone growth and metamorphosis, and give the enemies a longer time to feed on the larvae.1o. When a larva feeding on a pure algal diet metamorphoses into a carnivorous bottom stage, a ‘physiological revolution’ occurs and a huge waste of larvae might be expected. Experiments have, however, shown that this is not the case.11. Young pelagic larvae are photopositive and crowd near the surface; larvae about to metamorphose are photonegative. Larval polychaetes, echinoderms, and presumably also prosobranchs, may prolong their pelagic life for days or weeks until they find a suitable substratum. Forced towards the bottom by their photonegativity and transported by currents over wide bottom areas, testing the substratum at intervals, their chance of finding a suitable place for settling is much better than hitherto believed.12. Continuous currents from the continental shelf towards the open ocean may transport larvae from the coast to the deep sea where they will perish. Such conditions may (for instance in the Gulf of Guinea) deeply influence the composition of the fauna, while in other areas (European western coast, southern California) they seem to be only of small significance.13. The toll levied by enemies appears to be the most essential source of waste among the larvae. A list of such enemies, comprising other pelagic larvae, holoplank-tonic animals and bottom animals, is given on p. 2o. A medium-sized Mytilus edulis, filtering 1–4 1. of water per hour, may retain and kill about 100,000 pelagic lamellibranch larvae in 24 hr. during the maximum breeding season in a Danish fjord.14. Species reproducing in a vegetative way, by fission, laceration, budding, etc., might be expected to have good chances of competition in such areas where conditions for sexual reproduction are unfavourable. Nevertheless, they only supply a rather small percentage of the animal populations of all Recent seas, probably because their intensity of reproduction is low and because they are unable to spread to new areas. Most forms reproducing in a vegetative way have sexual reproduction as well.15. Pelagic development is nearly or totally suspended in the deep sea, and is restricted to the shelf faunas. In the arctic and antarctic seas pelagic development is nearly or totally suppressed, even in the shelf faunas, but starting from here the percentage of forms with pelagic larvae gradually increases as we pass into warmer water, reaching its summit on the tropic shelves.16. In order to survive in high arctic areas a planktotrophic, pelagic larva has to complete its development from hatching to metamorphosis within I–I ½ months (i.e. the period during which phytoplankton production takes place) at a temperature below 2–4o C. Most larvae, that is in 95% of the species, are unable to do so and have a non-pelagic development, but if a pelagic larva is able to develop under these severe conditions the planktotrophic pelagic life seems to afford good opportunities even in the Arctic. Thus the 5 % of arctic invertebrates reproducing in this way comprise several of the species which quantitatively are most common within the area.17. The antarctic shore fauna has poor conditions similar to those of the Arctic. The longest continuous periods of phytoplankton production are 2 and 3 weeks respectively, and pelagic larvae have, in order to survive, to complete their development within this short space of time at a temperature between 1 and 4o C. Accordingly, non-pelagic development is the rule, but most arctic species are able to support their non-pelagic development by means of much smaller eggs than the antarctic species, where brood protection and viviparity is dominant. The antarctic fauna has apparently had a longer time to develop its tendency to abandon a pelagic life. The greater the size of the individual born, the smaller its relative food requirements and the better its chance of competing under poor food conditions.18. The relatively few data on reproduction in deep sea invertebrates point to a non-pelagic development. The larvae of such forms, in order to develop through a planktotrophic pelagic stage, would have to rise by the aid of their own locomotory organs through a water column 2000–4000 m. high or more (often with counteracting currents) to the food producing surface layer, and to cover the same distance when descending to metamorphose and settle.19. The ecological features common to the deep sea, the arctic and the antarctic seas, which enable the same animals to live and to reproduce there, contribute to explain the ‘equatorial submergence’ of many arctic and antarctic coastal forms.20. In the tropical coastal zones where the percentage of species with pelagic larvae reaches its maximum, the production of food for the larvae takes place much more continuously than in temperate and arctic seas, because light conditions enable the phytoplankton to assimilate all the year round. The tropical species of marine invertebrates breed (in contrast to temperate and arctic species) within such different seasons that their larval stock, taken as a whole, is more or less equally distributed in the plankton all the year round. This makes the competition in the plankton less keen.21. The fact that a mode of reproduction and development, well fit for an arctic area, is unfit in a temperate or tropical area of the sea is probably one of the main reasons for the restricted distribution of species.22. In most groups of marine invertebrates the individual species have only one mode of reproduction and development, which accordingly restricts their area of distribution. In the polychaetes, however, the individual species often show an astonishing lability in their mode of reproduction and development which enables them to compete in wide areas of the sea. Thus, out of the Western European species of polychaetes, 28-4% have been found also in the Indian Ocean, and 18%, at least, along the Californian coast, while the corresponding number of Western European echinoderms, prosobranchs and lamellibranchs found also in the Indian Ocean and California amounts to less than 2%.23. The pelagic or non-pelagic development of marine prosobranchs has proved to be a very fine ‘barometer’ for ecological conditions. Recent observations, still not elaborated, seem to indicate that the shape of the top whorls, the apex, of the adult shells of prosobranchs may show whether the species in question has a pelagic or a non-pelagic development. This discovery may also give us valuable information about the larval development in fossil species, and help us to form an idea about ecological conditions in sea areas from earlier geological periods.
Variation in life history characteristics was examined in three closely related species of univoltine grasshopper, Praxibulus sp., Kosciuscola cognatus and K. usitatus, along three altitudinal transects in South East Australia. With increasing altitude females lay fewer eggs in total over the summer season but lay their eggs in larger clutches. This pattern of variation, which is not related to variation in egg size, is observed both between and within species. The relationship between clutch size and altitude is similar in all three species but quite distinct reproductive strategies are maintained between species even where different species are found together at the same altitude. It is proposed that both the length and predictability of the summer growing season could be impratant in determining the evolution of life history characteristics along the altitudinal gradient.
Onchidoris muricata (Mller) and Adalaria proxima (Alder and Hancock) are sympatric, potentially competing species of dorid nudibranchs, which preferentially graze the cheilostome polyzoan Electra pilosa (L.). O. muricata is small and lays small eggs which hatch as poorly-developed planktotrophic veliger larvae. A. proxima is larger and reproduces by means of larger eggs which hatch, as well-developed lecithotrophic larvae, that can metamorphose within approximately 24 h of release. A. proxima larvae can feed in the plankton, but do not require extrinsic nutrition to undergo complete development. Both species spawn in February–april, and have a strictly annual life-cycle. Comparisons of the calorific content of spawn have shown that A. proxima apportions a greater number of calories to reproduction, but that O. muricata makes a greater relative effort. A. proxima shown considerable individual variability in reproductive effort, which fails to correlate with, body size or rate of spawning. A more deterministic situation applies to O. muricata, because body size and fecundity follow an allometric relationship. It appears that there is a threshold of absolute energy required to support the lecithotrophic larval strategy in nudibranchs, and that this is not attained by the smaller species, O. muricata. A. proxima thus appears to have both reproductive strategies open to it, and to have adopted lecithotrophy in order to offset the unpredictability of energy available for reproduction.
Comparison of the life-histories of two species pairs of caridean decapods, each pair containing a polar and a more temperate-water species (Chorismus antarcticus (Pfeffer, 1887)/Pandalus montagui Leach, 1814 and Notocrangon antarcticus (Pfeffer, 1887)/ crangon crangon (Linnaeus, 1758), suggested that in each case the polar species was more of a K-strategist than was the temperate species. In particular there were striking differences in brood size, egg weight and maturity of the newly hatched larvae. Measurements of individual annual reproductive effort, RE, as g fresh weight eggs per g fresh weight female indicated that in both species pairs the RE of the polar K-strategist was significantly less than that of the comparable temperate water r-strategist. Results expressing RE as g total egg lipid per g fresh weight female were equivocal. These data are discussed in relation to available autecological information for Anterctic marine invertebrates and it is concluded that many features of the polar benthos are explicable in terms of a general evolution of typical K-strategies. The role of low temperature in the widespread evolution of K-strategies may be crucial; consideration of this leads to a re-appraisal of cold-adaptation.
Adjacent populations of Nassarius pauperatus differ significantly in how hungry their members are. The numbers of eggs and egg capsules produced are positively correlated with how hungry members of a population are, but the average number of eggs per capsule is negatively correlated with hunger. These results were confirmed in a laboratory experiment using two groups from the same population maintained with different levels of food.
The significance of this behaviour is discussed and the hypothesis proposed that the flexibility of reproductive patterns is correlated with dispersive ability.
The distribution of various types of larval development among marine bottom invertebrates has been discussed on the basis of ecological evidence by Thorson (1936, 1946, 1950, 1952) and Mileikovsky (1961b, 1965). The information at hand is reviewed anew in this paper and is re-evaluated in the light of modern pertinent literature. The interrelationships between certain larval types and their distribution are not as rigid and direct as originally assumed. This can be proved even by the copy book example of the distribution of the various forms of development among species of the coastal gastropod genus Littorina. Especially among species with wide distributional areas, local populations may exhibit greater diversity in larval types than has previously been thought. Different types of larval development have now become known to exist in different populations of opisthobranch gastropods and lamellibranchs, i.e., in invertebrate groups in which such variability had been ruled out by Thorson. Variability in the type of larval development within given species — as a function of geographical, seasonal and other environmental parameters —is also more common in other marine bottom invertebrates than formerly considered. Marine bottom invertebrates are characterized not only by the 3 main different types of larval development proposed by Thorson (pelagic, direct, viviparous), but also by a fourth type: demersal (free non-pelagic) development. This fourth type occurs at all water depths and in all geographic zones of the oceans. The most important of the 4 types is pelagic (planktotrophic) development. Thorson's rule (decrease in numbers of species possessing pelagic development from the Equator towards the Poles, and from shallow-shelf waters to greater oceanic depths) is well substantiated by new data. However, one correction is necessary: pelagic development is not completely absent in the abyssal zone, as was proposed by Thorson (1950, and later), but is represented in it by at least several species belonging to various groups of invertebrates, and is also fairly common in the bathyal zone. A detailed analysis of the distributional pattern of the different types of development of marine bottom invertebrates must further take into consideration asexual reproduction with all its different modifications. Asexual reproduction in benthonic invertebrates is ecologically significant because of its common occurrence in nature; in numerous species it is also important as a biological supplement to sexual reproduction. The vast majority of species inhabiting the shallow-shelf zone and, partly, the higher levels of the slope zone of ocean areas located roughly between the polar circles, reveals development by means of planktotrophic larval stages. In the highest latitudes and on the slopes to abyssal depths—characterized by low water temperatures, scarcity of food, increasing hydrostatic pressure and other environmental peculiarities—other types of larval development prevail and, progressively, replace pelagic development with increasing latitude or depth. The distributional patterns of the various types of development among marine bottom invertebrates form one of the most important factors determining the basic distributional dynamics of the whole benthos in all oceans, both in the geological past and at the present time.
The growth and spawning of Lacuna pallidula and L. vincta were measured in the laboratory over 7 months. In both cases, there were significant differences between the mean number of eggs per batch or weight of egg batches from females of the same species and also between rates of spawning by females of the same species. The reproductive effort of L. vincta, estimated by the ratio total spawn weight: body weight and by the time taken to exceed body weight in cumulative spawn, is approximately twice that of L. pallidula. L. vincta has a long-lived planktotrophic larva, while L. pallidula has direct, lecithotrophic development, and therefore in this instance planktotrophic development seems to be more expensive to the parent than lecithotrophic development. Published work on two Pacific seastars leads to the opposite conclusion, and it is suggested that the paradox can be resolved in terms of r-K-selection theory. In both cases, the r-selected species has a higher reproductive effort, notwithstanding that the snail is planktotrophic and the seastar lecithotrophic in development.
This paper considers the adaptive significance of two different reproductive methods in two co-occurring, competing sea stars. The smaller (3 to 8 g mean wet weight) Leptasterias hexactis broods relatively few, large young in the winter, while the large (300 to 650 g mean wet weight) Pisaster ochraceus broadcasts relatively many, small eggs each spring. L. hexactis matures at a small size (2 g wet weight) in about 2 years, and P. ochraceus matures at a larger size (70 to 90 g wet weight) in about 5 years (Menge, 1974). As in many broadcasting asteroids, gonad and storage organ indices of P. ochraceus are inversely related over time, and maximum storage-organ index correlates with the summer feeding maximum (Mauzey, 1966). In contrast, both organ indices of L. hexactis and feeding increase and are positively correlated until early autumn, when feeding activity begins to decline. At this time the male gonad index continues to rise, and the storage-organ index drops. In contrast, both organ indices of females rise. Spawning occurs from November to January. Thereafter storage-organ indices decline in females, presumably because females draw upon energy reserves while brooding; storage-organ indices rise in males, presumably because males do not brood and can feed if food is available. The primary cause for the differences between annual reproductive cycles of P. ochraceus and L. hexactis is suggested to be patterns of food availability for the released young (planktonic food for the broadcasted young of P. ochraceus and benthic prey for the brooded young of L. hexactis. Estimates of pre-maturity survival and post-maturity longevity indicate that the probability of survival per individual of young P. ochraceus is vastly lower than that of L. hexactis. However, once mature, P. ochraceus has a much longer expected lifespan. Brooding is suggested to be a coadaptive consequence of competition-induced small size. Assuming planktonic mortality rates in this environment are roughly constant across broadcasting species, I suggest that a small broadcasting species could not produce enough offspring in its expected lifespan to replace itself. This hypothesis is partly supported by some simple simulations. Broadcasting is suggested to permit rapid location and utilization of spatially and temporally unpredictable, but highly desirable, resources by allowing rapid and widespread dispersal. Brooders presumably cannot disperse rapidly and must rely on more reliable, but perhaps less desirable, resources. Factors affecting reproductive patterns in marine invertebrates include (1) food availability for both adults and offspring, (2) planktonic mortality rates, (3) interactions between species and latitudinal changes in these factors, and (4) various physical factors. This paper suggests that competition and predation can have an important effect on the evolution of reproductive methods, a possibility heretofore largely ignored. Although several similar examples of co-occurring species' pairs which differ in reproductive method and size are available, the role of adult interactions is unknown in these examples.
Population studies were conducted on the eastern fence lizard in South Carolina, Texas, Ohio, and Colorado. Hatching occurs in early to middle summer and well into the fall in southern populations, but is restricted to late summer and early fall in Colorado and Ohio. The hatchlings in Texas reach a mature size in 3 months and these lizards, as well as those in South Carolina, reproduce before they are a year old. In Colorado and Ohio the lizards do not mature until almost 2 years of age, but at a larger size than those in Texas or South Carolina. Lizards in the four populations differ significantly in average clutch size (7.4-11.8) and in clutch frequency (1-3) and in egg size (.23-.42 g per egg). In all populations there is a significant positive correlation between clutch size and body and the regression lines for these variables differ in slope between populations. Survivorships of eggs, hatchlings, yearlings, and adults differ among the populations and these differences have been related indirectly to increased predation in the southern and western populations. The adult mortality rates are inversely related to population density. Life tables for the populations show large differences among the populations in the contributions made by each age class to the total population replacement rate. The life table characteristics of each population show that the measured parameters are consistent with maintenance of stable population numbers even though the life history strategies are clearly different. Evolutionary explanations are provided for these differences and the relevance of the data to the concept of r- and K-selection is discussed.
Job number (X5685) added acc. to DOCREP assignment