Fig 6 - uploaded by Villy Christensen
Content may be subject to copyright.
Contexts in source publication
Context 1
... distinct patches (Cohorts 1 to 6) of larvae were recognized (Fig. 8a to e ) . Cohorts 1 and 6 were found off Aberdeen, Cohort 2 in the Firth of Forth area (over Marr Bank) and Cohorts 3, 4 and 5 in a large area extending to the south of Turbot Bank (ca 75 km east of Buchan Ness) (Fig. 1). Cohorts 3, 4 and 5 could only be discriminated on the basis of their spatial distributions (larval length increased ...
Context 2
... of larval distributions (Fig. 8f) occurred in (Cohorts 2 to 5) or close to (Cohorts 1 and 6) frontal waters, and were, in all cases, confined to within < 30 J m-3 (cf. Fig. 3). Significant concentrations of larvae were not encountered in the strongly stratified waters east of ca 0". The drift trajectories (Fig. 8f) suggest a net southward movement of larval patches at ...
Context 3
... of larval distributions (Fig. 8f) occurred in (Cohorts 2 to 5) or close to (Cohorts 1 and 6) frontal waters, and were, in all cases, confined to within < 30 J m-3 (cf. Fig. 3). Significant concentrations of larvae were not encountered in the strongly stratified waters east of ca 0". The drift trajectories (Fig. 8f) suggest a net southward movement of larval patches at a speed of 2 to 4 km d-l. Cohorts with centres on the immediate mixed side of the front (Cohorts 1 and 6) tended to move faster than cohorts with centres in frontal water. Cohort 2, in particular, seemed to be retained at the 'southern' front for a prolonged period and the ...
Context 4
... estimates of drift speed and direction (Fig. 8f) and growth rates (see below), it is possible to calculate the approximate position of the larval cohorts at the time of hatching (hatching length 6.7 mm) and, thus, to identify the spawning grounds (Fig. 8f). Cohorts 3 to 5 apparently stem from a common spawning ground (at Turbot Bank), whereas the other larval cohorts origi- nate ...
Context 5
... estimates of drift speed and direction (Fig. 8f) and growth rates (see below), it is possible to calculate the approximate position of the larval cohorts at the time of hatching (hatching length 6.7 mm) and, thus, to identify the spawning grounds (Fig. 8f). Cohorts 3 to 5 apparently stem from a common spawning ground (at Turbot Bank), whereas the other larval cohorts origi- nate from 3 different spawning grounds (Cohort 1: off Aberdeen; Cohort 2: Marr Bank; Cohort 6: off Buchan Ness). These banks are well-known spawning grounds for North Sea herring (Saville ...
Context 6
... relationship between spatial and temporal varia- tion in water column stability and phytoplankton bio- mass and production is well documented in the litera-LONGITUDE Fig. 8. Clupea harengus. (a to e) Spatial distributions of larval cohorts on 5 consecutive surveys (Survey 0: 7 to 9 Sep; Survey 1: 16 to 21 Sep; Survey 2: 23 to 28 Sep; Survey 3: 8 to 12 Oct; Survey 4 : 17 to 19 Oct). Symbols: (+++++) Cohort l ; (----) Cohort 2; ( -) Cohort 3 t 4 + 5; (---) Cohort 6. For Surveys 0 to 2, the outermost ...
Similar publications
Citations
... Previously reported field-based estimates of prey preference of herring larvae agree poorly. Some studies reported a clear preference of larvae for copepods, with a shift from smaller to larger stages or species of copepods with increasing larval size (e.g., Kiørboe et al. 1988;Wilson et al. 2018). More recent studies suggested that young herring larvae are generalist foragers, ingesting a wider range of proto-and microplankton organisms (de Figueiredo et al. 2005;Bils et al. 2016;Denis et al. 2016). ...
... Larger larvae (> 18 mm) were predicted to experience food-limitation in winter at Downs, but not in autumn at Buchan/Banks, where larvae approached their maximal temperature-and size-specific growth capacity at the vast majority of the stations. These results agree well with Kiørboe et al. (1988) and Buckley and Durbin (2006) who showed a strong prey-limitation of young larvae, but not of larger larvae captured at the same station. ...
Recruitment success of marine fishes is generally considered to be highly dependent on larval growth and survival. In temperate ecosystems, fish larvae are sensitive to food limitation during the low productivity seasons, particularly if water temperatures and concomitant larval metabolic costs increase due to climate change. We combined 7 years of in situ sampling of larval fish, novel observations on zooplankton via automated image analyses, and larval physiological modeling to explore feeding conditions of Atlantic herring larvae (Clupea harengus) in the North Sea. The observed plankton size-structure was close to the theoretical optimum for larval foraging, but not the biomass. Our results for autumn larvae supported Hjort's critical period hypothesis: small first-feeding larvae were predicted to have a high probability of starvation, whereas larvae > 13 mm were able to reach their maximal growth capacity. In winter, the majority of herring larvae of all tested sizes (5–27 cm) experienced food-limitation with over 35% probability of starvation. Sensitivity analysis suggested that young herring larvae improve their growth performance and probability of survival if feed not only on copepods and their life-stages but include other microplankters in their diet. Given projected warming of the North Sea, our model predicts that herring larvae would require 28% (35%) more prey biomass in autumn (winter) to sustain their growth and survival in the future. This finding together with the ongoing low recruitment of North Sea herring underscore the importance of future micro- and mesoplankton monitoring within a scope of wintertime larval fish surveys. © 2023 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.
... Los procesos como los frentes, los remolinos y las surgencias son factores determinantes en la distribución espacial y estructural de la comunidad zooplanctónica en escala de cuenca y local (Hinrichsen, 2009;Avendaño-Ibarra et al., 2013). Los remolinos y frentes pueden ser mecanismos de retención y concentración de huevos, larvas y juveniles de diversos organismos (Iles y Sinclair, 1982;Bolz y Lough, 1984;Wroblewski y Cheney, 1984;Kiørboe et al., 1988;Lobel y Robinson, 1988;Sournia, 1994;Rodríguez et al., 2004;Avendaño-Ibarra et al., 2013); mientras que los filamentos que se desprenden de eventos de surgencias, como también de los remolinos, pueden ser mecanismos de dispersión (Flierl y Wroblewski, 1985;Myers y Drinkwater, 1989;Roy, 1998;Smith y Suthers, 1999;Bécognée et al., 2009;Avendaño-Ibarra et al., 2013). ...
... However, there is some evidence of density-dependent effects in larval stages (Cowan et al., 2000;Houde, 2008). In Clupea harengus (Atlantic herring) in the northwest North Sea, larvae hatched from demersal eggs tend to drift and concentrate within the front region at a given time, which subjects larvae to competition for food and in turn contributes to density-dependent effects on traits (Kiørboe et al., 1988). Poor recruitment of the 1981 year class of Theragra chalcogramma (walleye pollock) could be due to the depletion of prey availability in early-life stages caused by dense aggregations of larvae (Duffy-Anderson et al., 2002). ...
Reproductive success can be influenced by the match or mismatch between the spawning season and optimal environmental conditions for larval survival. However, it is challenging to understand how temporal factors affect population dynamics. In the central Seto Inland Sea, Hiuchi‐nada, western Japan, the recruitment of Japanese anchovy (Engraulis japonicus) has markedly decreased in the last decade. To explore the causes of this decline, egg survey and commercial catch data from 1994 to 2019 (26 years) between April and August were used to examine egg production, hatch date, and early survival in relation to environmental factors. Otolith microstructure analysis indicated that most landed larval and juvenile fish (recruits) hatched in May and June. Egg and recruit abundances were negatively correlated over the study period. The survival indices from hatching to recruitment were higher in waters at 16–24°C in a given season until the mid‐2000s. Thereafter, they decreased over the studied temperature range and remained relatively low over the last five years. The copepod nauplii densities from 2015 to 2019 were significantly higher than those from 2002 to 2005 due possibly to the effect of increasing temperature, but the ratio of copepod nauplii density to larval density in May and June from 2015 to 2019 was approximately 34% and 66% of those from 2002 to 2005, respectively. These findings and the hydrodynamic features of these waters suggest that the recent decline in recruit abundance is partly due to a decrease in larval survival in response to increasing intracohort competition for prey in early‐life stages.
... Embedded into the global framework of persistent large-scale and mesoscale fronts are myriads of transient dynamic features such as mesoscale and submesoscale eddies, subsurface lenses, Lagrangian coherent structures, and upwelling zones as well as short-lived meso-and submesoscale fronts created by various processes, e.g., upwelling fronts in the wakes of hurricanes and typhoons. Marine animals have been observed seeking out such dynamic features, particularly mesoscale eddies and Lagrangian coherent structures/fronts as reported by Fronts are the most ecologically important circulation and structural features of the ocean realm (Laurs and Lynn, 1977;Holligan, 1981;Krause et al., 1986;Le Fèvre, 1987;Kiørboe et al., 1988;Olson et al., 1994;Polovina et al., 2000Polovina et al., , 2001Acha et al., 2004;Bakun, 2006;Palacios et al., 2006;Bost et al., 2009;Dunn et al., 2011;Scales et al., 2014a;Woodson and Litvin, 2015;Watanuki et al., 2016;Snyder et al., 2017;Cox et al., 2018;Sarma et al., 2018;Martinetto et al., 2020). Each large-scale front is an ecotone defined as a narrow transition zone between two adjacent marine ecosystems. ...
This paper provides a concise review of remote sensing of ocean fronts and its applications in marine ecology and fisheries, with a particular focus on the most popular front detection algorithms/techniques: Canny (1986), Cayula and Cornillon (1990, 1992, 1995), Miller (2004, 2009), Shimada et al. (2005), Belkin and O’Reilly (2009), and Nieto et al. (2012). A case is made for feature-based approach in marine ecology and fisheries that emphasizes fronts as major structural and circulation features of the ocean realm that play key roles in various aspects of marine ecology.
... There are many benefits to spawning within a frontal system boundary layer, such as a pycnocline or thermocline. Pycnocline boundary layers can act as a retention feature for planktonic organisms, which includes larval fish and prey that support early growth (Kiørboe et al. 1988;Bjorkstedt et al. 2002;McManus and Woodson 2012). Retention within the boundary layer provides organisms an environment independent of the larger masses of water, subjecting them to reduced turbulence and flow velocities (Doostmohammadi et al. 2012), and likely a more predictable and stable dispersal mechanism (Paris and Cowen 2004;Nickols et al. 2012). ...
Coastal marine fishes that form spawning aggregations most commonly exhibit a two-point movement pattern, with locations separated by migration: home range to spawning aggregation site and return to home range. However, the bonefish, Albula vulpes, partakes in a unique three-point spawning migration. Bonefish migrate up to 80 km from shallow water home flats to form nearshore pre-spawning aggregations (PSA) before moving offshore to spawn. Although these broad patterns have previously been documented, details of the offshore spawning-associated diving behavior have yet to be rigorously examined. Using active acoustic telemetry and sonar data in 2019 in Abaco, The Bahamas, we provide a complete account of bonefish offshore spawning movements and novel deep diving behavior to 137.9 m. Bonefish were continuously observed at depths ≥ 100 m for 2 h; a time period that included multiple depth changes and culminated in a spawning ascent to 67.3 m at 0.57 m s−1. These new data on bonefish offshore movements and deep dives, coupled with CTD data, suggest that bonefish actively spawn at pycnoclines and thermoclines. Two previous tracking attempts (2013, 2018) at this location reflect spatiotemporal plasticity in spawning, a behavior counter to other aggregation forming fishes. This is the first detailed documentation of such deep spawning for a shallow water coastal fish species. The ecological motivation for diving to the deepest depths remains speculative. Future work must examine the dynamic relationship between bonefish diving behavior, spawning site selection, and oceanographic features.
... While it is well-established that meso scale frontal features cause major variations in physical oceanography and the distributions of organisms (e.g. Kiørboe et al. 1988, Munk et al. 2002, Lee et al. 2005, the use of an in situ plankton imager allowed for a substantially higherresolution investigation of river plume processes than has previously been possible. ...
... Despite the seaward flow of plume water near the surface, a net landward movement of denser, coastal shelf water along the bottom resulted in the retention of fish eggs spawned in and around the mouth of Mobile Bay (Marley 1983). Temperate fishes, particularly those that prey upon zooplankton, frequently spawn near mesoscale (20−200 km) oceanographic features such as river plumes, eddies, and other frontal zones potentially to directly release larvae in regions that support high prey concentrations (Kiørboe et al. 1988, Munk et al. 1999, Richardson et al. 2009). Upon hatching, larvae may use be havioral responses (e.g. ...
River plumes discharging into continental shelf waters have the potential to influence the distributions, predator-prey relationships, and thus survival of nearshore marine fish larvae, but few studies have been able to characterize the plume environment at sufficiently fine scales to resolve the underlying mechanisms. We used a high-resolution plankton imaging system and a sparse convolutional neural network to automate image classification of larval fishes, their planktonic prey (calanoid copepods), and gelatinous planktonic predators (ctenophores, hydromedusae, and siphonophores) over broad spatial scales (km) and multiple pulses of estuarine water exiting Mobile Bay (Alabama, USA) into the northern Gulf of Mexico from 9-11 April 2016. Fine-scale (1 m) plankton distributions were examined to analyze predator-prey relationships across 3 distinct plume regimes that varied by degree of wind-forcing and mixing rates. In calm wind conditions, the water column was highly stratified, and fish larvae and zooplankton were observed aggregating in a region of river plume-derived hydrodynamic convergence. As winds strengthened, the water column was subjected to downwelling and highly turbulent conditions, and there was decreasing spatial overlap between larval fishes and their zooplankton prey and predators. Our results indicate that high-discharge plume regimes characterized by strong wind-forcing and turbulence can rapidly shift the physical and trophic environments from favorable to unfavorable for fish larvae. Multiple pathways for both nearshore retention and advective dispersal of fish larvae were also identified. Documenting this variability is a first step toward understanding how high discharge events and physical forcing can affect fisheries production in river-dominated coastal ecosystems worldwide.
... For herring, numerical simulations revealed that larval dispersal is affected by abiotic factors such as persistent oceanographic features like the Norwegian coastal current (NCC) (Skagseth et al., 2015;Zimmermann et al., 2019). Variability in thermal regimes, light and turbulence can also contribute to variation in survival (Kiørboe et al., 1988), growth (Husebø et al., 2007) and abundance (Maravelias and Reid, 1997) of herring larvae, with consequences for subsequent recruitment success (Toresen and Østvedt, 2000). However, while contemporary modelling approaches can provide important insights into the mechanisms underlying dispersal of herring, in most cases they are missing an important component -horizontal orientation and swimming. ...
The dispersal of fish larvae during the early life stages plays an important role in recruitment. Together with oceanographic processes, larval orientation and swimming behavior significantly influences dispersal. However, currently there is no information of larval behavior in situ for most subpolar species. The Atlantic herring (Clupea harengus) is an ecologically and commercially important component of the North Atlantic ecosystem. This species has sustained a large fishery for over a century, and its stocks have experienced both dramatic collapse and recovery. The Atlantic herring is highly migratory, making it challenging for researchers to determine with certainty the structure and discreteness of different herring stocks. In this context, studying the behavior of herring larvae at sea is crucial for a deeper understanding of their dispersal. However, to date information on the orientation behavior and swimming abilities of herring larvae in situ is missing. In this study, we coupled in situ observations and laboratory experiments to investigate whether herring larvae display orientation when swimming in situ, and which mechanisms/cues they could use. We video recorded the orientation behavior of 208 herring larvae between 14 and 28 days post hatch (DPH) in the coastal Norwegian North Sea while they drifted in transparent behavioral chambers. We also tested the orientation of 136 larvae in a magnetic laboratory, in which they were deprived of any external cue and where we could modify the direction of the magnetic field. We report evidence that herring larvae have a significant preferred orientation direction to the southeast, which does not change between 14 and 28 DPH. Moreover, our results suggest that sunlight plays a key role as larvae had a highly significant orientation towards the sun during sunny weather, but they lost this ability, and exhibited lower precision in their orientation, under an overcast sky. We did not find evidence of magnetic compass orientation, indicating that the orientation direction of herring larvae is not magnetic, at least at this life history stage. Larvae swam at an average speed of 0.36–0.40 cm/s and reached maximum speeds of 3–3.36 cm/s. These results demonstrate that 14–28 DPH herring larvae are capable of orienting in situ. Possible implications of this orientation behavior for larval transport in Norwegian waters are also explored.
... The composition of larval fish assemblages varies spatially and temporally because of the behavior of larvae (Gray and Miskiewicz 2000), as well as oceanographic transport and mixing processes (Auth 2008;Muhling et al. 2008). In marine ecosystems, oceanographic processes, e.g., currents, fronts, and upwelling, have been considered as mechanisms of retention, concentration, or dispersion (Govoni and Pietrafesa 1994;Sabatés et al. 2007) that may enhance or diminish the survival of larvae (Kiørboe et al. 1988). Biological factors, such as the depth distribution of fish larvae (Olivar and Sabatés 1997), prey availability (Olivar et al. 2010), spawning strategy , and migratory behavior (Hare et al. 2001) of adult fishes, are also usually important for the formation and maintenance of fish larvae assemblages. ...
The mesoscale distribution of fish larvae and its relationships with oceanographic features were examined among six cruises from four seasons in the Kuroshio waters off eastern Taiwan between May 2003 and November 2004. A total of 389 taxa (including two morpho-types) of fish larvae belonging to 106 families and 204 genera were identified from the samples. Families with higher numbers of species were Myctophidae, Scombridae, Stomiidae, Paralepididae, and Gobiidae. Maurolicus japonicus (relative abundance, 7.8%), Vinciguerria nimbaria (7.4%), Sigmops gracilis (6.5%), Cyclothone alba (5.5%), and Diaphus stubby type (5.0%) were the five most abundant taxa. Fish larvae abundance was lower in February and August 2004 than in other cruises, but without spatial variation in distribution. Although the predominant species were similar among cruises, species number and diversity were higher in May 2003 and lower in August 2004. Two larval fish assemblages were distinguished, one containing mainly autumn, winter, and spring and the other mainly spring and summer collections. The taxonomically diverse larval fish assemblage demonstrated that the Kuroshio waters off eastern Taiwan are a major transition zone between tropical and subtropical faunas. These communities are enriched by northward advection of larvae and early juveniles of many tropical species into subtropical waters via the Kuroshio Current. In addition, offshore transport of neritic fish larvae also increased the diversity of the larval fish assemblage in Kuroshio waters. The distribution of fish larvae was related to oceanographic features, with surface salinity, chlorophyll, and food sources being correlated to the abundance of fish larvae.
... The growth rate of Downs herring larvae observed in the present study was high and comparable (0.26 mm days −1 ) to previous studies at the same period either in the same area (0.165 mm days −1 ; Hempel 1960), during autumn in the central of North Sea (0.13-0.24 mm days −1 ; Kiørboe et al. 1988) or during spring in the West of Scotland (0.17 mm days −1 ; Checkley 1984, 0.22 mm days −1 ; Campana and Moksness 1991). It is also comparable to field studies in other areas such as spring in the Baltic Sea (0.13-0.26 mm days −1 ; Weber 1971, 0.21-0.29 mm days −1 ; Waldman 1961), and in the Clyde (0.33 mm days −1 ; Geffen 1986). ...
Evaluating fish larval condition in terms of nutrition and growth is essential as it will influence their development and survival capacity. The present study aims to investigate larval condition of Downs herring (Clupea harengus L.) during winter in the Eastern English Channel and Southern Bight of the North Sea. Four condition indices including ingestion rate based on gut fluorescence, instantaneous growth based on RNA/DNA, DNA/C ratios, and otolith microstructure were combined at an individual scale on herring larvae collected during the 2015 International Bottom Trawl Survey—MIK sampling. The four indices demonstrated a clear shift in the larval condition occurring at a larval size of 13 mm. While smaller larvae were shown to feed and grow, larger larvae exhibited a slower growth rate though actively feeding. This suggests that 13 mm could be a critical size for Downs herring larvae. This ontogenetic shift in the larval condition is discussed regarding environmental conditions, diet shift, and growth strategies. It is concluded that the shift from an omnivorous to a carnivorous diet constitutes an additional critical step besides such as the shift from endogenous to exogenous nutrition.
... The growth rate of Downs herring larvae observed in the present study was high and comparable (0.26 mm d -1 ) to previous studies at the same period either in the same area (0.165 mm d -1 ; Hempel, 1960), during autumn in the central of North Sea (0.13-0.24 mm d -1 ; Kiørboe et al., 1988) or during spring in the West of Scotland (0.17 mm d -1 ; Checkley, 1984, 0.22 mm d -1 , Campana andMoksness, 1991). It is also comparable to field studies in other areas such as spring in the Baltic Sea (0.13-0.26 mm d -1 ; Weber, 1971; 0.21-0.29 mm d -1 ; Waldman, 1961) and in the Clyde (0.33 mm d -1 ; Geffen, 1986). ...
The larval condition of Downs herring during the critical period was investigated between 2008 and 2015 in the eastern English Channel and Southern Bight of North Sea from data collected during the International Bottom Trawl Survey (IBTS). First, the study of the feeding strategy from gut contents analysis using two complementary approaches (electronical microscopy and measure of fluorescence) revealed a shift in the feeding diet occurring at a larval size of 13 mm. Smaller larvae had an omnivorous and a more diversified diet composed of numerous protist and small zooplanktonic preys whereas bigger larvae had a less diversified diet composed mainly of bigger zooplanktonic prey. Along with the diet shift, combination of four condition indices (ingestion rate, RNA/DNA and DNA/C ratios and otoliths) also revealed important changes in the nutritional status and growth of these larvae. Larvae smaller than 13 mm had a sustainable nutrition and growth whereas larger larvae depicted low growth rate. This could reflect a change in the energy-allocation strategy from a growth-oriented strategy towards a more storage-oriented strategy. These ontogenetic changes in the larval condition suggest that the diet shift occurring at 13 mm could constitute the core of the critical period for Downs herring larvae.
