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Population dynamics and production of the planktonic copepods in a eutrophic inlet of the Inland Sea of Japan. III. Paracalanus sp
Abstract
Population dynamics and production of the calanoid copepodParacalanus sp. were studied from November 1986 to November 1987 in Fukuyama Harbor, a eutrophic inlet of the Inland Sea of Japan. This species was perennial, with a large abundance peak in June/July and small peaks in September/October and November/December. During a year of investigation, 15 generations Gould be detected. For each generation, the mean population egg production rate and the mean daily midstage abundance front NIII to CV were determined to obtain a survival curve from egg to CV. The mortality was extremely high during the early life stages: on average only 7.1% of the eggs produced might survive into NIII. This high mortality might be caused by predation by sympatric omnivorous copepods, in addition to sinking loss of eggs from the waten column. The biomass ofParacalanus sp. showed marked seasonal variations largely in parallel with numerical abundance. The instantaneous growth rate of each developmental stage increased exponentially with temperature up to 20 C, above which the rate was constant. The annual integrated production rate was 734 mg C m–3 yr–1 or 5.5 g C m–2 yr–1.
... One such planktonic copepod, Paracalanus parvus s. l. (hereinafter P. parvus), is a neritic calanoid species. Paracalanus parvus is a dominant copepod species in terms of abundance and biomass in various waters, including the Yellow Sea [4], the Korean coast [5][6][7], northern East China Sea [8], Inland Sea of Japan [9], and the California Current off the Oregon coast [10]. For example, P. parvus in the southeastern coast of Korea accounted for 26.8% of mesozooplankton over the four years [6]. ...
... The egg production rate (EPR) of copepods is used not only as a proxy for secondary production, but also as an indicator of environmental change [11][12][13][14][15][16][17][18]. Studies on the EPR of P. parvus have been conducted in different waters around the world: Skagerrak in the North Atlantic [19], off Newport, Oregon, USA [12], Bahía Magdalena, Mexico [20], Fukuyama Harbor, Japan [9], and Jiaozhou Bay in the Yellow Sea, China [21]. Domestic studies on the EPR of P. parvus in Korea include the Yeongsan River and Seomjin River Estuary [22,23], Jangmok Bay in the southern coastal waters of Korea [24], and the coastal waters of Busan [17]. ...
... Domestic studies on the EPR of P. parvus in Korea include the Yeongsan River and Seomjin River Estuary [22,23], Jangmok Bay in the southern coastal waters of Korea [24], and the coastal waters of Busan [17]. However, intensive studies on the EPR of P. parvus have been conducted only over 1 year or during a specific season [9,19,21,24]. To elucidate the average seasonal variation in copepod EPRs, studies longer than 1 year are required [11,18] as the quantitative variability in zooplankton is high in shallow waters, such as at Busan Harbor [25,26]. ...
We measured the monthly egg production rate (EPR) of Paracalanus parvus s. l. (P. parvus) at a fixed station in Busan Harbor from January 2020 to December 2021 to elucidate the seasonal variation in the EPR and the factors involved. Over the 2 years, the monthly EPR ranged from 0.5 to 47.0 eggs female−1 d−1 (average 13.3 eggs female−1 d−1). The seasonal mean EPR was high in spring (April to June) and summer (July to September) and low in autumn (October to December) in both years. Egg hatching success was high (average 94%). Monthly nauplii production in the P. parvus population ranged from 9 to 37,123 ind. m−3 d−1 (average 4605 ind. m−3 d−1), with a peak in March and May in 2020 and in April in 2021. The monthly EPR of P. parvus was more dependent on chlorophyll-a concentration than on water temperature. Nauplii production was dependent on the abundance of adult females, while the chlorophyll-a concentration had a positive effect on nauplii production. In this study, while there was no clear seasonal variation in the abundance of adult females, the EPR showed a clear pattern of seasonal variation. These results imply that for monitoring potential environmental changes in Busan Harbor, measuring the EPR of copepods may be a better indicator than copepod abundance.
... As such, it is noted that the total biomass of all copepod species appeared to fluctuate over the study period, but the ratio of the biomass of the former group dramatically decreased. Our analyses of the effect of SST on copepod biomass also suggested that each species appeared to be relatively stenothermal, probably because there were certain thermal limits on egg production and embryonic development (Liang and Uye 1996b;Uye, 2000). The biomass peaks of C. sinicus, C. affinis, and O. similis gradually shifted in cooler water in a given season (May-June), following decreases in their biomass in the last decade. ...
... Meanwhile, P. parvus consumes a variety of prey items such as diatoms and microprotozoans. P. parvus females have the potential to keep spawning in waters over a wide temperature range up to 25 • C through short-term alternations of generations in the Seto Inland Sea (Liang and Uye, 1996b). This appears to be in contrast to the findings in other copepod species found in cooler water in a given season, including C. sinicus and O. similis. ...
Anthropogenic and/or climate-driven changes in zooplankton dynamics may serve as a bottom-up regulator of productivity of small pelagic fish. In the central Seto Inland Sea of Japan, the abundance of the recruit fish of Japanese anchovy (Engraulis japonicus) has markedly declined in the last decade under oligotrophication. However, the link between the reproductive success of anchovy and environmental variation is largely unclear. This study explored the potential association between changes in the zooplankton (copepods) community structure and the reproductive condition of anchovy in this oligotrophic sea using survey data from spring and summer of 2001–2019. The community structure of copepod species changed markedly in May–July, covering the main spawning season of anchovy, as decreases in the biomass of several copepods found in cooler water in a given season (May–June) were observed. Although relationships between chlorophyll a concentrations and the copepod biomass were unclear, the recent decline of their cooler-water copepods may be attributed to the influences of elevated SST and decreasing levels of chlorophyll a. The latter may be associated with decreasing nitrogen levels. Among these species, Calanus sinicus and Corycaeus affinis could be important prey items for anchovy from the analyses of prey selectivity and relationships between the relative condition factor of females and the copepod biomass. The egg size–temperature relationships of anchovy appeared to be associated with the relative condition factor of females and survival rates in the early stage of life, suggesting that females with a poor body condition produced smaller eggs in recent years. Maternal food manipulation experiments supported the assumption that larvae born to females fed a restricted food ration exhibited lower starvation tolerance and slower growth than born to females provided feed ad libitum. These findings suggest that the reproductive success of anchovy could be subject to bottom-up trophic drivers mediated by maternal contributions to offspring viability, and this partly explains why the level of anchovy recruitment has rapidly declined in the last decade.
... Calanus sinicus CIV기부터 CVI기 시료의 개체당 건중량과 탄소량 자료 로부터 도출한 길이-무게 관계식은 다음과 같다 (Fig. 1). (Liang and Uye 1996;Kang and Hong 1998;Kang and Kang 2005). 또한 요각류의 건중량도 길이와 마찬가지로 계절에 따라 변한다 (Conover and Huntley 1991;Green et al. 1993 Fig. 2. Comparison of the relationships of prosome length (PL) and body weight (BW) of copepodites and adult of Calanus sinicus from the different authors (see Table 3 for data of PL and BW) ...
Length-weight relationship of Calanus sinicus
... Our results were supported by the findings of Keister and Tuttle [70], who suggested that species in the genus Oithona might migrate to the surface layer due to subsurface hypoxia during upwelling events. The Calanoida copepod Paracalanus parvus, playing an important role in ocean fisheries with relatively higher abundance in the western subtropical Pacific, is widely distributed in temperate and tropical regions [71][72][73][74]. In addition, P. parvus was reported as a coldwater mass indicator species in northeast Taiwan during the northeast monsoon season [5]. ...
In order to better understand the cold dome influence on zooplankton community structure , zooplankton samples were collected during the southwest monsoon prevailing period from the southeast waters of the East China Sea. To reduce the bias caused by different sampling months, the samples were collected in June 2018 and in June 2019. An obvious cold dome activity was proven by images of remote sensing satellites during the June 2018 cruise. In contrast, the research area was much affected by open sea high temperature and water masses during the June 2019 cruise. Significant differences in water conditions were demonstrated by surface seawater temperature, salinity, and dissolved oxygen concentrations between the two cruises. Nevertheless, no significant differences were observed concerning mesozooplankton in general, copepods, large crustaceans, other crustaceans, and pelagic molluscs between the June 2018 and June 2019 cruises. However, the mean abundance of gelatinous plankton was significantly different with 1213.08 ± 850.46 (ind./m 3) and 2955.93 ± 1904.42 (ind./m 3) in June 2018 and June 2019, respectively. Noteworthy, a significantly lower mean abundance of meroplankton, with 60.78 ± 47.32 (ind./m 3), was identified in June 2018 compared to 464.45 ± 292.80 (ind./m 3) in June 2019. Pearson's correlation analysis also showed a highly positive correlation of gelatinous plankton and meroplankton with sea surface temperature (p < 0.01). The variation of salinity showed a significant negative correlation with gelatinous plankton abundance (p < 0.05), and a highly significant negative correlation with the abundance of meroplankton (p < 0.01). Only the abundance of meroplankton showed a positive correlation with dissolved oxygen concentrations (p < 0.05). The copepod communities were separated in two groups which were consistent with sampling cruises in 2018 and 2019. Based on the specificity and occupancy of copepods, Macrosetella gracilis, Oithona rigida, Cosmocalanus darwinii, Paracalanus parvus, and Calocalanus pavo were selected as indicator species for the cold dome effect in the study area during June 2018, whereas the indicator species of warm water impact in the open sea were Calanopia elliptica, Subeucalanus pileatus, Paracalanus aculeatus, and Acrocalanus gibber during the June 2019 cruise.
... The growth rate of the copepod Paracalanus parvus would be inhibited if the water temperature went above 20 • C [55]. When the nearshore water temperature was higher than 26 • C, the high value area of Paracalanus parvus had a tendency to move outward [56]. In Bohai bay, the counterclockwise residual current brings cooler seawater to the mouth of the bay, favoring the Paracalanus parvus to gather at the mouth of the bay. ...
Zooplankton play a pivotal role in connecting primary producers and high trophic levels, and changes in their temporal and spatial distribution may affect the entire marine ecosystem. The spatial and seasonal taxonomic composition patterns of mesozooplankton in Bohai Bay were investigated in relation to a number of water parameters. Bohai Bay is a eutrophic semi-enclosed bay with dynamic physico-chemical conditions influenced by terrestrial inputs and seawater intrusion. The results showed that under the condition of terrigenous input, the diversity of mesozooplankton species near the eutrophic Haihe River Estuary and Jiyun River Estuary was lower than that in the central Bohai Bay, with gelatinous Oikopleura dioica as the dominant species. The mesozooplankton diversity was highest in the bay mouth affected by seawater intrusion, and the dominant oceanic species, mainly copepods Corycaeus affinis, Calanus sinicus, and Oithona similis, entered the inner bay from the bay mouth. Meanwhile, the abundance of mesozooplankton in summer was significantly higher than that in autumn. Compared with historical data, the dominant species in Bohai Bay has evolved from arrow worm Sagitta crassa to copepod Paracalanus parvus, probably due to global warming, indicating the effects of human activities on the succession of mesozooplankton community.
... In the subarctic North Pacific, where our P sites were located, seasonal blooms of phytoplankton are rapidly consumed by microzooplankton, which in turn are consumed by large Copepoda, such as Neocalanus (Landry and others 1993). Neocalanus species live for more than 1 year (Kobari and Ikeda 1999;Tsuda and others 1999), whereas smaller species, such as Paracalanus, have life cycle of less than 1 year (Liang and Uye 1996). Therefore, the produced organic matter is accumulated at a higher TP after the phytoplankton bloom because the turnover time increases as TP and body weight increase, which allows Neocalanus to play an important role as a food reservoir for their predators, such as fish, during low production periods (Ikeda and others 2008). ...
Biomass pyramids in natural food webs provide insights into multitrophic ecosystem functioning. We measured the integrated trophic position (iTP), which reflects the average efficiency of biomass transfer through trophic pathways, of 14 mesozooplankton communities in the western North Pacific. Compound-specific nitrogen isotope analysis of amino acids for composite mesozooplankton biomass indicated that the iTP values of marine mesozooplankton communities and their biomass pyramids are essentially controlled by biodiversity, body weight, and species turnover. Offshore communities with lower diversity and higher iTP were dominated by large copepods with slow turnover, such as Neocalanus, whereas nearshore communities with higher diversity and lower iTP were characterized by several smaller, fast turnover species belonging to Calanus, Paracalanidae, Eucalanidae, and Metridinidae. The observed iTP values (2.36 ± 0.32) indicate different topologies in biomass pyramids in different sites, where inverted pyramids are found in less diverse communities. The results also suggest that iTP can be linked to food chain length (FCL), a conventional proxy for the biomass pyramid. Combining iTP and FCL in the future studies will be a powerful approach to better understand factors controlling food web structure and dynamics.
... Between 200 and 300 individuals produced over 40,000 individuals after 50 d in an in situ mesocosm experiment in Saanich Inlet, BC (Gibson and Grice, 1978). Paracalanus produced six generations within nine months (Digby, 1950) and had a development rate of 44 d in 9.7 • C seawater (Liang and Uye, 1996). Calanus pacificus has been shown to develop from egg to adult in 26 d at 11.4 • C (Huntley and Brooks, 1982). ...
During the 2014–2016 Pacific marine heatwave (MHW), seabird die-offs, declines in forage fish populations, and the appearance of subtropical marine taxa (e.g. ocean sunfish, skipjack tuna) occurred in the northern Gulf of Alaska; however, the response of the zooplankton community to the MHW remains poorly understood. As part of the Gulf Watch Alaska program in Cook Inlet, zooplankton, phytoplankton, and a suite of oceanographic variables were collected monthly from 2012 to 2018. Surface zooplankton were collected via vertical tows (0–50 m) with a 333 μm bongo net along with CTD data and chlorophyll a concentration. Generalized additive models showed that seasonal zooplankton abundance peaked mid-June and declined into late January. During the MHW, monthly temperature anomalies ranged from +0.2 to +2.8 °C in 2015 and 2016, but monthly means of large lipid-rich calanoid copepods showed no clear declines in abundance compared to before and after the MHW suggesting that these copepods had some resiliency. An indicator species analysis using 88 of the most common zooplankton taxa produced five groups of zooplankton based on season. A BIO-ENV Best model showed that the environmental variables best explaining the observed zooplankton community structure included SST, temperature of the top 50 m of the water column, mixed layer depth (MLD), MLD temperature, and integrated chl a (ρ = 0.3491, Mantel Test: r = 0.3491, α < 0.05). Seasonal transitions of community groups displayed a phenological shift in 2016 when the late spring group of meroplanktonic larvae and the fall group of warm water copepods (WWC) typical of the Northern California Current system appeared earlier and persisted for longer compared to before and after the MHW. WWC abundance increased during the fall seasons of the MHW. Throughout 2015–2016, the elevated abundance of WWC compared to previous years and before/after the MHW suggested that warmer than average oceanographic conditions in the winter of 2015/2016 may have been sufficient to allow for an overwintering population in this area. A potential overwintering population of a warm water predatory copepod, Corycaeus anglicus, was observed and may have direct fine scale predator/prey impacts on zooplankton in this region.
... Small juveniles, <35-mm SL; large juveniles, ≥35-mm SL. B, Levins' diet breadth index T A B L E 4 Body dimensions and carbon contents of the four major prey items taken by Japanese jack mackerel (Trachurus japonicus) juveniles Note: The mean prosome length was converted to the approximate carbon contents based on equations from Liang and Uye (1996) for P. parvus s.l., Uye (1988) for C. sinicus, and Uye (1982) for euchaetid copepods. The mean total length of ostracods was converted to dry weight (DW) based on equations from Kaeriyama and Ikeda (2002). ...
We examined interannual variations in the diet of Trachurus japonicus juveniles in relation to prey density and recent 5‐day instantaneous growth rate (IGR) in the southwestern part of the Sea of Japan (SJ) in late spring during 2011–2013. Habitat temperature of juveniles in 2011 was lower than the other 2 years. In all 3 years, more than 97% of juveniles had food in the stomach. Small juveniles <35‐mm standard length (SL) fed mainly on adult female Paracalanus parvus s.l., the most dominant calanoid copepod in the water column, without a significant interannual difference. In 2011 and 2012, large juveniles ≥35‐mm SL predated heavily upon adult female Calanus sinicus which form a high‐energy food for the juveniles. In contrast, in 2013, the large juveniles preyed on a large number of a variety of small‐sized prey items, such as P. parvus s.l., euchaetid copepods, and ostracods. In 2011 when the feeding condition was considered to be favorable, but the habitat temperature was lowest, the IGR of large juveniles was markedly lower than in the other 2 years. Meanwhile, there was no significant difference in the IGR between 2012 and 2013 when the diet composition was markedly different, but habitat temperature was comparable. The present observations indicate that the between‐year difference in juvenile IGR was not explained well by variations in the diet composition. Instead, habitat temperature was concluded to be the more dominant factor causing the observed between‐year differences in the IGR in the southwestern SJ.
Copepods are major components of zooplankton community over the world oceans. They have important roles to transfer primary production to higher trophic levels of marine ecosystems. In general, secondary production can be estimated by animal body weight multiplying growth rate. Animal body weight has been accurately measured, but there is little information which method is relevant for estimation of growth rate. Thus, we have little knowledge on confidence of secondary production compared with that of primary produc tion. In the present study, we review methods to measure growth rate for natural popula tion of pelagic copepods and indicate the assumptions, the advantages and disadvantages. Seven methods have been used for measurements of growth rates of natural copepod population; natural cohort, artificial cohort, moult rate, egg production, nucleic acids ratio, enzyme activity and empirical models. Each method has specific assumptions and advantages/disadvantages dependent on environmental conditions and ecological properties of copepods. Because there is no method to be applied for all copepods, it is important to select some methods with compensation between the advantages and the disadvantages and to compare the growth rate estimates.
The abundance of adult males, females, and copepodites, and sex ratio of a Temora turbinata population and seawater hydrology were studied from 2018 to 2019 in waters off northeast Taiwan, northwest Pacific Ocean. The hydrological parameters showed significant differences between sampling months caused by interactions of Kuroshio, East China Sea water, and the China Coastal Current. The highest average abundance was recorded from the June 2018 cruise with 2903.92 ± 3499.47 (inds. m−3), followed by a cruise in June 2019 with an average abundance of 1990.64 ± 1401.55 (inds. m−3). The sex ratio ranged between 0.25 and 2.33; the records were significantly higher in samples of June 2018 than during other sampling cruises (one-way ANOVA). The spatiotemporal distribution of T. turbinata showed a clear pattern of seasonal changes among sampling stations and distribution zones. Abundance of females and copepodites correlated significantly positive (r = 0.755, p < 0.001), whereas sex ratio (r = 0.247, p = 0.119) did not correlate significantly. The present study revealed that the abundance of T. turbinate was highest in June and was positively correlated with seawater temperature; furthermore, this is the first time the in situ sex ratio of T. turbinata in western Pacific waters has been reported.
Twenty-one species of copepods are identified from the vicinity of Mukaishima in Bingo-Nada. Among them, Eucalanus mucronatus, E. subcrassus, E. crassus, Acrocalanus gracilis, Pseudodiaptomus marinus and Microsetella norvegica are newly found in this area. The first three species occurred only in autumn. Acrocalanus gracilis occurred from autumn to early winter. The other two species were found throughout the year. Dominant species in copepod communities were Paracalanus parvus, Acartia clausi, Oithona similis, O. nana, Oncaea venusta, Corycaeus affinis and Microsetella norvegica. They thrived throughout the year except for Acartia clausi which does not exist from August to November. Of the other species, Calanus helgolandicus, Centropages abdominalis, Euterpina acutifrons mainly appeared in the colder season, and Centropages yamadai, Calanopia thompsoni, Labidocera bipinnata, Pontellopsis tenuicauda, Acartia erythraea and Tortanus forcipatus mainly in the warmer season.
In the investigations at the three stations in Hiuchi-nada, twenty-one species of copepods were identified. The period of occurrence of every species was, in the main, similar to that recorded in my previous work in Bingo-nada situated in the northern outside of Hiuchi-nada. Among them, Paracalanus parvus, Oithona similis, Oithona nana, Corycaeus affinis, Corycaeus andrewsi and Microsetella norvegica occurred dominantly or subdominantly. From the results of the present survey and my previous work in Bingo-nada, the biological characteristic of the sea area extending across the central part of the Setonaikai from south to north is considered as follows. In the northern part of Bingo-nada area, the water mass is mingled violently with the polluted water caused by the sewage of factories and cities, and so Acartia clausi and Oithona nana are dominant. On the contrary, in the central part of Hiuchi-nada area where Oithona similis occurred dominantly, such effect of the polluted water seems to be the weakest.
The in situ rate of egg production ( B ) and female size of Paracalanus parvus , a particle‐grazing copepod, water temperature, and the concentrations of chlorophyll a and particulate nitrogen were measured in 31 collections from the euphotic zone of the sea off southern California. B was correlated positively with chlorophyll a and female size and negatively with temperature. A multiple regression of log B on chlorophyll a , particulate nitrogen, female size, and temperature accounts for 44% of the variation in log B.B was predicted best by an empirical function of food concentration when the food available in nature was considered to be phytoplankton rather than of all types of particulate matter >5 µ .
An index of immediate food limitation was derived from laboratory data as a function of food concentration. When applied to extensive measurements of chlorophyll a in the euphotic zone, this index indicates that Paracalanus was often food limited and that food limitation increased along an onshore‐offshore transect. Paracalanus was rarely food limited in Santa Monica Bay.
Point estimates of mortality of zooplankton in the field, based on relative numbers of individuals of different developmental stages observed in samples, require either a knowledge of the initial input of young or assumptions about constancy of input and constancy of mortality over adjacent stages. As the initial input is rarely known and the assumptions of constancy are probably often violated, the resulting uncertainty should be made evident in the estimates. This can be done by reporting the ranges of values of the mortality coefficients that would be consistent with the observed relative numbers of individuals. Methods of calculating these ranges are given.
The growth of marine, particle-feeding zooplankton is likely to be limited by the availability of food in open ocean environments, but not in coastal regions. The maximum production ratio of zooplankton to phytoplankton is predicted to be greater at higher temperatures, ranging from 6.4% at 0oC to 20.3% at 25oC. A method is described for using the modified von Bertalanffy growth equation to estimate in situ production of zooplankton. -Authors