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Richard D.m. Nash - One of the best experts on this subject based on the ideXlab platform.
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Growth dynamics of European plaice Pleuronectes Platessa L. in nursery areas: A review
Journal of Sea Research, 2014Co-Authors: Benjamin J. Ciotti, Richard D.m. Nash, Timothy E. Targett, Audrey J GeffenAbstract:Young-of-the-year European plaice Pleuronectes Platessa L. (hereafter: ‘YOY plaice’) in shallow, sandy areas is a long- and intensively-studied species and an ideal model for understanding growth dynamics in fish nurseries. In order to provide an overview of and access point to this rich literature and to guide future research on juvenile fish growth dynamics, we review patterns of growth variation in YOY plaice following settlement and evaluate evidence for underlying causes, including maximum growth, temperature, prey conditions and competition. A decline in growth rate during late summer and autumn was the clearest and most widespread pattern, but was not clearly related to any of the potential causes previously considered. Interannual growth variation was substantial and despite evidence that intraspecific competition was responsible, other possible causes were also supported and others were only rarely assessed. Growth also varied considerably at a range of spatial scales (100s of m–100s of km). Causes of small-scale ( 200 km) growth variation remain poorly understood and while intermediate-scale growth variation has been related to prey conditions and intraspecific competition, the role of interspecific competition requires further investigation. Therefore, despite clear evidence for growth heterogeneity at numerous spatiotemporal scales, underlying causes remain elusive. We highlight some principal challenges to measuring and understanding the complex and scale-dependent causes of growth variation. To overcome these challenges, and therefore resolve important nursery processes for juvenile fish, we recommend more detailed and spatiotemporally explicit investigations of growth, metabolic processes and physiological energetics in situ; a focus on possible proximate and ultimate factors driving these dynamics; and development of new hypotheses to explain growth variation starting with general physical features that define nursery environments.
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Mortality through the early life-history of fish: What can we learn from European plaice (Pleuronectes Platessa L.)?
Journal of Marine Systems, 2012Co-Authors: Richard D.m. Nash, Audrey J GeffenAbstract:Abstract It is difficult to estimate natural mortality for many marine fish populations, especially during the transition period from larvae to juveniles, because the appropriate data are scarce. Plaice (Pleuronectes Platessa) is an exception since it has been studied extensively. The study of mortality rates in juveniles is made easier because the nursery grounds are inshore and generally less than 5 m deep. This contribution considers the factors affecting mortality rates for eggs and larvae, and for settlement and nursery ground phases. There are problems associated with estimating mortality rates, especially for juveniles because immigration into nursery areas at the beginning of the season and emigration of larger individuals off nursery grounds in the latter part of the season confound losses due to mortality. The shifts in mortality schedules and the causes through the early life history are investigated in relation to concepts such as ‘nursery ground carrying capacity’ and ‘self-thinning’. Predation in the pelagic phase is probably density independent and a source of inter-annual variability in survival of early life-history stages. Predation mortality during the nursery ground phase is most likely density dependent. However, there is a need for further in-depth study, especially during the period of settlement.
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Sub-cohort dynamics of 0-group plaice, Pleuronectes Platessa L., in the Northern Irish Sea: Settlement, growth and mortality
Journal of Experimental Marine Biology and Ecology, 2011Co-Authors: Audrey J Geffen, Richard D.m. Nash, Andrew J.p. HarwoodAbstract:The settlement, growth and mortality of plaice (Pleuronectes Platessa L.) were examined on a small nursery ground (Port Erin Bay, Isle of Man) in the Irish Sea in 1993 and between 1996 and 2000. The timing, duration and strength of juvenile settlement varied between years and were positively correlated with the duration and quantity of egg production. Otolith increment counts were used to determine the age and metamorphosis and/or settlement dates of fish and to compare settlement patterns inferred from catch data with those inferred from age data. The catch data suggested two ‘pulses’ of settlement in Port Erin Bay whereas the otolith age data indicated three main settlement events. Over the years the first sub-cohort was generally the largest and overall this sub-cohort suffered the highest mortality. This first sub-cohort may have a “high risk” strategy and swamp potential predators early in the settlement period, with the result that the second sub-cohort generally has faster growth rate and lower mortality. A release of predatory pressure on the second sub-cohort could be a cause of large year classes in plaice populations. Growth rates were lowest for fish in the first sub-cohort, likely reflecting density-dependent effects and less optimal environmental conditions early in the year. The variations in instantaneous mortality rate between sub-cohorts, as well as inter-annually within sub-cohorts, illustrate the complex dynamics in the structure of these juvenile plaice populations on the nursery grounds. Global environment change effects are visible in the wider Irish Sea plaice population dynamics, with temperature dependent nursery ground processes as one of the contributing mechanisms.
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development validation and field application of an rna based growth index in juvenile plaice Pleuronectes Platessa
Journal of Fish Biology, 2010Co-Authors: Benjamin J. Ciotti, Richard D.m. Nash, Timothy E. Targett, Michael T Burrows, Robert S Batty, Audrey J GeffenAbstract:A general mechanism relating RNA concentration and growth rate is derived from four physiological assumptions and developed into a growth index for juvenile plaice Pleuronectes Platessa. The index describing instantaneous growth rates (G, day?1) in the laboratory with the lowest Akaike information criterion with small-sample bias adjustment was a function of RNA concentration (R, inline image), temperature (T, ° K), body mass (M, g) and DNA concentration (D, inline image): G = ?0 + ?RR + ?TT + ?T2T2 + ?MM + ?DD + ?RTRT. RNA concentration began to respond to changes in feeding conditions within 8 days, suggesting that the index reflects growth rate in the short-term. Furthermore, the index distinguished between rapid growth and negative growth of juvenile P. Platessa measured directly in laboratory and field enclosures, respectively. An application of the RNA-based growth index at two beaches on the west coast of Scotland suggested that the growth of juvenile P. Platessa varies considerably in space and time and is submaximum in late summer.
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The concept of fecundity regulation in plaice (Pleuronectes Platessa) tested on three Irish Sea spawning populations
Canadian Journal of Fisheries and Aquatic Sciences, 2007Co-Authors: James Kennedy, Peter R. Witthames, Richard D.m. NashAbstract:The fecundity of European plaice (Pleuronectes Platessa) in the Irish Sea between 2000 and 2004 was esti- mated during the spawning season for fish in the three main spawning areas (Liverpool Bay, the Cumbrian coast, and the western Irish Sea) and one small spawning group on the west coast of the Isle of Man. Fecundity was also esti- mated during September of 2003 and 2004. The aim of this was to assess the variability in fecundity between areas and years in the Irish Sea and also to identify when differences in fecundity become apparent in the maturation cycle. There were variations in fecundity on both the temporal and spatial scales. The greatest variation in fecundity between years occurred in the western Irish Sea, whereas there was no variation between years in the southeastern Irish Sea (Liverpool Bay). There was no difference in fecundity between areas or years during September. The maximum fecun- dity in plaice is determined by the total weight of the fish at the end of follicle recruitment in the ovary, and differ- ences in the fecundity of each population are the result of different levels of down-regulation in the period between the end of follicle proliferation and spawning.
Audrey J Geffen - One of the best experts on this subject based on the ideXlab platform.
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Growth dynamics of European plaice Pleuronectes Platessa L. in nursery areas: A review
Journal of Sea Research, 2014Co-Authors: Benjamin J. Ciotti, Richard D.m. Nash, Timothy E. Targett, Audrey J GeffenAbstract:Young-of-the-year European plaice Pleuronectes Platessa L. (hereafter: ‘YOY plaice’) in shallow, sandy areas is a long- and intensively-studied species and an ideal model for understanding growth dynamics in fish nurseries. In order to provide an overview of and access point to this rich literature and to guide future research on juvenile fish growth dynamics, we review patterns of growth variation in YOY plaice following settlement and evaluate evidence for underlying causes, including maximum growth, temperature, prey conditions and competition. A decline in growth rate during late summer and autumn was the clearest and most widespread pattern, but was not clearly related to any of the potential causes previously considered. Interannual growth variation was substantial and despite evidence that intraspecific competition was responsible, other possible causes were also supported and others were only rarely assessed. Growth also varied considerably at a range of spatial scales (100s of m–100s of km). Causes of small-scale ( 200 km) growth variation remain poorly understood and while intermediate-scale growth variation has been related to prey conditions and intraspecific competition, the role of interspecific competition requires further investigation. Therefore, despite clear evidence for growth heterogeneity at numerous spatiotemporal scales, underlying causes remain elusive. We highlight some principal challenges to measuring and understanding the complex and scale-dependent causes of growth variation. To overcome these challenges, and therefore resolve important nursery processes for juvenile fish, we recommend more detailed and spatiotemporally explicit investigations of growth, metabolic processes and physiological energetics in situ; a focus on possible proximate and ultimate factors driving these dynamics; and development of new hypotheses to explain growth variation starting with general physical features that define nursery environments.
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Otolith oxygen and carbon stable isotopes in wild and laboratory-reared plaice (Pleuronectes Platessa)
Environmental Biology of Fishes, 2012Co-Authors: Audrey J GeffenAbstract:The relationship between water temperature, growth rate, and otolith isotopic ratios was measured for juvenile plaice ( Pleuronectes Platessa ) reared at two temperatures (11 and 17°C) and two feeding regimes (1 and 3 prey items·ml^−1). The otolith isotope ratios in individual fish ranged from −2 to −4 for carbon isotope ratios (δ^13C) and from 0.2 to 1.9 for oxygen isotope ratios (δ^18O). The otolith oxygen isotope ratios were significantly affected by water temperature, but not by feeding level, and there were no significant synergistic effects. The fractionation of oxygen isotopes during otolith growth was independent of individual growth rate. Carbon isotope ratios were not significantly affected by food ration or water temperature, but were related to fish growth rate. The carbon isotope ratios were negatively correlated with fish length in the colder water treatments, and tended to increase with fish length in the warm water treatments. The laboratory-determined relationship between otolith oxygen isotope ratio and water temperature was applied to individuals of five species (plaice, cod, whiting, haddock, gurnard) collected in a single trawl sample. The otolith derived temperatures often overestimated measured water temperatures. The difference between real and estimated water temperatures varied between species, and the closest fit was for field-caught plaice.
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Mortality through the early life-history of fish: What can we learn from European plaice (Pleuronectes Platessa L.)?
Journal of Marine Systems, 2012Co-Authors: Richard D.m. Nash, Audrey J GeffenAbstract:Abstract It is difficult to estimate natural mortality for many marine fish populations, especially during the transition period from larvae to juveniles, because the appropriate data are scarce. Plaice (Pleuronectes Platessa) is an exception since it has been studied extensively. The study of mortality rates in juveniles is made easier because the nursery grounds are inshore and generally less than 5 m deep. This contribution considers the factors affecting mortality rates for eggs and larvae, and for settlement and nursery ground phases. There are problems associated with estimating mortality rates, especially for juveniles because immigration into nursery areas at the beginning of the season and emigration of larger individuals off nursery grounds in the latter part of the season confound losses due to mortality. The shifts in mortality schedules and the causes through the early life history are investigated in relation to concepts such as ‘nursery ground carrying capacity’ and ‘self-thinning’. Predation in the pelagic phase is probably density independent and a source of inter-annual variability in survival of early life-history stages. Predation mortality during the nursery ground phase is most likely density dependent. However, there is a need for further in-depth study, especially during the period of settlement.
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Sub-cohort dynamics of 0-group plaice, Pleuronectes Platessa L., in the Northern Irish Sea: Settlement, growth and mortality
Journal of Experimental Marine Biology and Ecology, 2011Co-Authors: Audrey J Geffen, Richard D.m. Nash, Andrew J.p. HarwoodAbstract:The settlement, growth and mortality of plaice (Pleuronectes Platessa L.) were examined on a small nursery ground (Port Erin Bay, Isle of Man) in the Irish Sea in 1993 and between 1996 and 2000. The timing, duration and strength of juvenile settlement varied between years and were positively correlated with the duration and quantity of egg production. Otolith increment counts were used to determine the age and metamorphosis and/or settlement dates of fish and to compare settlement patterns inferred from catch data with those inferred from age data. The catch data suggested two ‘pulses’ of settlement in Port Erin Bay whereas the otolith age data indicated three main settlement events. Over the years the first sub-cohort was generally the largest and overall this sub-cohort suffered the highest mortality. This first sub-cohort may have a “high risk” strategy and swamp potential predators early in the settlement period, with the result that the second sub-cohort generally has faster growth rate and lower mortality. A release of predatory pressure on the second sub-cohort could be a cause of large year classes in plaice populations. Growth rates were lowest for fish in the first sub-cohort, likely reflecting density-dependent effects and less optimal environmental conditions early in the year. The variations in instantaneous mortality rate between sub-cohorts, as well as inter-annually within sub-cohorts, illustrate the complex dynamics in the structure of these juvenile plaice populations on the nursery grounds. Global environment change effects are visible in the wider Irish Sea plaice population dynamics, with temperature dependent nursery ground processes as one of the contributing mechanisms.
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development validation and field application of an rna based growth index in juvenile plaice Pleuronectes Platessa
Journal of Fish Biology, 2010Co-Authors: Benjamin J. Ciotti, Richard D.m. Nash, Timothy E. Targett, Michael T Burrows, Robert S Batty, Audrey J GeffenAbstract:A general mechanism relating RNA concentration and growth rate is derived from four physiological assumptions and developed into a growth index for juvenile plaice Pleuronectes Platessa. The index describing instantaneous growth rates (G, day?1) in the laboratory with the lowest Akaike information criterion with small-sample bias adjustment was a function of RNA concentration (R, inline image), temperature (T, ° K), body mass (M, g) and DNA concentration (D, inline image): G = ?0 + ?RR + ?TT + ?T2T2 + ?MM + ?DD + ?RTRT. RNA concentration began to respond to changes in feeding conditions within 8 days, suggesting that the index reflects growth rate in the short-term. Furthermore, the index distinguished between rapid growth and negative growth of juvenile P. Platessa measured directly in laboratory and field enclosures, respectively. An application of the RNA-based growth index at two beaches on the west coast of Scotland suggested that the growth of juvenile P. Platessa varies considerably in space and time and is submaximum in late summer.
A D Rijnsdorp - One of the best experts on this subject based on the ideXlab platform.
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reconstructing the effects of fishing on life history evolution in north sea plaice Pleuronectes Platessa
Marine Ecology Progress Series, 2016Co-Authors: Fabian M Mollet, Ulf Dieckmann, A D RijnsdorpAbstract:Growing evidence suggests that fishing may induce rapid contemporary evolution in certain life-history traits. This study analyzes fisheries-induced changes in life-history traits describing growth, maturation, and reproduction, using an individual-based eco-genetic model that captures both the population dynamics and changes in genetic trait values. The model was successfully calibrated to match the observed life-history traits of female North Sea plaice 'Pleuronectes Platessa' around the years 1900 and 2000. On this basis, we report the fllowing findings. First, the model indicates changes in 3 evolving life-history traits: the intercept of the maturation reaction norm decreases by 27%, the weight-specific reproductive-investment rate increases by 10%, and the weight-specific energy-acquisition rate increases by 1%. Together, these changes reduce the weight at maturation by 46% and the asymptotic body weight by 28% relative to the intensification of fishing around 1900. Second, while the maturation reaction norm and reproductive-investment rate change monotonically over time, the energy-acquisition rate follows a more complex course: after an initial increase during the first 50 yr, it remains constant for about 30 yr and then starts to decline. Third, our analysis indicates that North Sea plaice has not yet attained a new evolutionary equilibrium: it must be expected to evolve further towards earlier maturation, increased reproductive investment, and lower adult body size. Fourth, when fishing continues in our model 100 yr into the future, the pace of evolution slows down for the maturation reaction norm and the rate of energy acquisition, whereas no such slowing down is expected for the rate of reproductive investment.
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bio energetics underpins the spatial response of north sea plaice Pleuronectes Platessa l and sole solea solea l to climate change
Global Change Biology, 2012Co-Authors: Lorna R Teal, Piet Ruardij, Ralf Van Hal, Tobias Van Kooten, A D RijnsdorpAbstract:Climate change is currently one of the main driving forces behind changes in species distributions, and understanding the mechanisms that underpin macroecological patterns is necessary for a more predictive science. Warming sea water temperatures are expected to drive changes in ectothermic marine species ranges due to their thermal tolerance levels. Here, we develop a mechanistic tool to predict size- and season-specific distributions based on the physiology of the species and the temperature and food conditions in the sea. The effects of climate conditions on physiological-based habitat utilization was then examined for different size-classes of two commercially important fish species in the North Sea, plaice, Pleuronectes Platessa, and sole, Solea solea. The two species provide an attractive comparison as they differ in their physiology (e.g. preferred temperature range). Combining dynamic energy budget (DEB) models with the temperature and food conditions estimated by an ecosystem model (ERSEM), allowed spatial differences in potential growth (as a proxy for habitat quality) to be estimated for 2 similar to years with contrasting temperature and food conditions. The resulting habitat quality maps were in broad agreement with observed ontogenetic and seasonal changes in distribution as well as with the recent changes in distribution which could be attributed to an increase in coastal temperatures. Our physiological-based model provides a powerful tool to explore the effect of climate change on the spatio-temporal fish dynamics, predict effects of local or broad-scale environmental changes and provide a physiological basis for observed changes in species distributions.
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fisheries induced adaptive change in reproductive investment in north sea plaice Pleuronectes Platessa
Canadian Journal of Fisheries and Aquatic Sciences, 2005Co-Authors: A D Rijnsdorp, R E Grift, Sarah B M KraakAbstract:Life history theory predicts that fishing may select for increased reproductive investment. A model of the reaction norm for reproductive investment in a capital breeder was developed to disentangle changes in reproductive investment from changes in growth rate in North Sea plaice (Pleuronectes Platessa). Trends in reproductive investment since 1960 were estimated as (i) the decrease in body weight of mature males and females between the start and end of the spawning period, (ii) the difference in weight of ripe and spent females, and (iii) the ovary weight of prespawning females. These estimates were related to somatic growth estimated by back-calculation of otoliths and temperature. The ovary weight and weight loss of females that had just started and just finished spawning did not reveal any trends. There was a significant increase in weight loss over the spawning season in both sexes, but much of this increase was likely due to changes in environmental conditions. Evidence for a fisheries-induced change in reproductive investment from our analyses thus remained inconclusive. However, fecundity and ovary-weight data from previous studies tentatively suggest that an increase in reproductive investment occurred between the late 1940s and the 1960s. Such an increase is consistent with a fisheries-induced evolutionary change
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low effective population size and evidence for inbreeding in an overexploited flatfish plaice Pleuronectes Platessa l
Proceedings of The Royal Society B: Biological Sciences, 2005Co-Authors: Galice Hoarau, Henk W Van Der Veer, A D Rijnsdorp, Jonbjorn Palsson, Eva E Boon, Dorris N Jongma, Steven Ferber, Wytze T Stam, Jeanine L OlsenAbstract:Overexploitation and subsequent collapse of major worldwide fisheries has made it clear that marine stocks are not inexhaustible. Unfortunately, the perception remains that marine fishes are resilient to large population reductions, as even a commercially 'collapsed' stock will still consist of millions of individuals. Coupled with this notion is the idea that fisheries can, therefore, have little effect on the genetic diversity of stocks. We used DNA from archived otoliths collected between 1924 and 1972 together with 2002 juvenile's tissue to estimate effective population size (Ne) in plaice (Pleuronectes Platessa). Ne was estimated at 20 000 in the North Sea and 2000 in Iceland. These values are five orders of magnitude smaller than the estimated census size for the two locations. Populations examined between 1924 and 1960 were in Hardy-Weinberg equilibrium, whereas populations examined after approximately 1970 were not. Extensive testing was performed to rule out genotyping artefacts and Wahlund effects. The significant heterozygote deficiencies found from 1970 onward were attributed to inbreeding. The emergence of inbreeding between 1950 and 1970 coincides with the increase in fishing mortality after World War II. Although the biological mechanisms remain speculative, our demonstration of inbreeding signals the need for understanding the social and mating behaviour in commercially important fishes.
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population structure of plaice Pleuronectes Platessa l in northern europe a comparison of resolving power between microsatellites and mitochondrial dna data
Journal of Sea Research, 2004Co-Authors: Galice Hoarau, A D Rijnsdorp, Wytze T Stam, A M T Piquet, H W Van Der Veer, Jeanine L OlsenAbstract:We used Single Strand Conformation Polymorphism (SSCP) of mtDNA control region to assess the population structure of the flatfish Pleuronectes Platessa (plaice), to compare these data with a previous study based on microsatellite loci, and to test for possible sex-biased dispersal. From 461 individuals, 163 haplotypes were identified across 11 locations. Diversity was higher with mtDNA (h =0.776 to 0.981; p = 0.0178 to 0.0298) as compared to microsatellite loci using the same samples (He = 0.721 to 0.77). Genetic diversity was lower in samples from Iceland and Faroe, as compared to the continental shelf samples. Although both classes of markers revealed a relatively strong differentiation between shelf and off-shelf populations (h = 0.1015 and h = 0.0351, respectively), only the mtDNA data were able to detect differentiation within the continental shelf, i.e., a North Sea-Irish Sea group which was weakly distinguishable from Norway (h = 0.0046), the Baltic (h = 0.0136) and the Bay of Biscay (h = 0.0162). No evidence was obtained for isolation by distance, nor for sex-biased dispersal. This study demonstrates the importance of using more than one class of markers, especially for species such as plaice, with large populations, high dispersal and recent colonisation histories. D 2004 Elsevier B.V. All rights reserved.
H W Van Der Veer - One of the best experts on this subject based on the ideXlab platform.
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population structure of plaice Pleuronectes Platessa l in northern europe a comparison of resolving power between microsatellites and mitochondrial dna data
Journal of Sea Research, 2004Co-Authors: Galice Hoarau, A D Rijnsdorp, Wytze T Stam, A M T Piquet, H W Van Der Veer, Jeanine L OlsenAbstract:We used Single Strand Conformation Polymorphism (SSCP) of mtDNA control region to assess the population structure of the flatfish Pleuronectes Platessa (plaice), to compare these data with a previous study based on microsatellite loci, and to test for possible sex-biased dispersal. From 461 individuals, 163 haplotypes were identified across 11 locations. Diversity was higher with mtDNA (h =0.776 to 0.981; p = 0.0178 to 0.0298) as compared to microsatellite loci using the same samples (He = 0.721 to 0.77). Genetic diversity was lower in samples from Iceland and Faroe, as compared to the continental shelf samples. Although both classes of markers revealed a relatively strong differentiation between shelf and off-shelf populations (h = 0.1015 and h = 0.0351, respectively), only the mtDNA data were able to detect differentiation within the continental shelf, i.e., a North Sea-Irish Sea group which was weakly distinguishable from Norway (h = 0.0046), the Baltic (h = 0.0136) and the Bay of Biscay (h = 0.0162). No evidence was obtained for isolation by distance, nor for sex-biased dispersal. This study demonstrates the importance of using more than one class of markers, especially for species such as plaice, with large populations, high dispersal and recent colonisation histories. D 2004 Elsevier B.V. All rights reserved.
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population structure of plaice Pleuronectes Platessa l in northern europe microsatellites revealed large scale spatial and temporal homogeneity
Molecular Ecology, 2002Co-Authors: Galice Hoarau, A D Rijnsdorp, Wytze T Stam, H W Van Der Veer, Jeanine L OlsenAbstract:Philopatry to spawning grounds combined with well-known migratory patterns in the flatfish Pleuronectes Platessa (plaice) has led to the hypothesis that regional populations may reflect relatively discrete, genetic stocks. Using six microsatellite loci we genotyped 240 adult individuals collected from locations in Norway, the Faeroe plateau, the Irish Sea, the Femer Baelt, Denmark, and the southern North Sea, and 240 0-class juveniles collected from five nursery-ground locations in Iceland, northwest Scotland, two sites in the Wadden Sea, and the Bay of Vilaine in Southern Brittany. The mean number of alloles/locus ranged from 5.3 to 20.4, with a mean of 13.9. Expected heterozygosity was uniformly high across all locations (multilocus H-exp = 0.744+/-0.02). Pairwise comparisons of theta among all 11 locations revealed significant differentiation between Iceland and all other locations (theta = 0.0290*** to 0.0456***), which is consistent with the deep-water barrier to dispersal in plaice. In contrast, no significant differentiation was found among any of the remaining continental-shelf sampling locations. This suggests that regional stocks are themselves composed of several genetic stocks under a model of panmixia which persists even to the spawning grounds. The presence of significant heterozygote deficiencies at all locations (not due to null alleles) suggests a temporal Wahlund effect yet the absence of significant population differentiation among continental shelf localities makes this explanation alone difficult to. reconcile. Sampling of eggs at the spawning grounds will be required to resolve this issue. Causes of the mismatch between genetic and geographical stocks is discussed in the context of high gene flow.
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the maximum growth optimal food condition hypothesis a test for 0 group plaice Pleuronectes Platessa in the dutch wadden sea
Marine Ecology Progress Series, 1993Co-Authors: H W Van Der Veer, J.ij. WitteAbstract:A test of the 'maximum growth/optimal food condition' (MG/OFC) hypothesis is described for 0-group plaice Pleuronectes Platessa L. in the western Dutch Wadden Sea. The MG/OFC hypothesis assumes optimal food conditions (i.e. no competition for superfluous food and hence no negative density-dependent growth) and consequently a maximum growth rate only determined by prevailing water temperature conditions. Growth of 0-group plaice subpopulations was determined for a number of areas differing in food abundance and composition (benthic biomass of potential food items) and density of 0-group plaice in both the intertidal and the sublittoral. Growth showed a positive relationship with food abundance, in both the intertidal and the sublittoral, falsifying the MG/OFC hypothesis. At similar food abundance, growth in the intertidal was always higher than in the sublittoral due to the presence of the lugworm Arenicola marina in the intertidal only. In the intertidal, growth was positively related to density of A. marina. The assumption of the MG/OFC hypothesis of no negative densitydependent growth was confirmed both in the intertidal and in the sublittoral, although it did not result in maximum growth rate for 0-group plaice everywhere in the field Differences in growth rate therefore do not necessarily reflect competition for food and density-dependent growth, but they might reflect differences in food composition and availability (searching and handling time).
Henk W Van Der Veer - One of the best experts on this subject based on the ideXlab platform.
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habitat quality of a subarctic nursery ground for 0 group plaice Pleuronectes Platessa l
Journal of Sea Research, 2010Co-Authors: Vânia Freitas, Joana Campos, Stig Skreslet, Henk W Van Der VeerAbstract:Abstract Habitat quality of a subarctic nursery ground in northern Norway for 0-group plaice Pleuronectes Platessa was investigated by following settlement, mortality and growth during 2005 and 2006. Newly settled individuals were first observed in the end of May to early June and settlement lasted until mid-July. Densities peaked in early July and were comparable to those reported in temperate nursery grounds. Mortality estimates after settlement differed between 0.062 d − 1 in 2005 and 0.025 d − 1 in 2006. Potential predators appeared to be rather similar as those reported in other areas: the brown shrimp Crangon crangon , the shore crab Carcinus maenas and demersal fish species (gadoids). Population mean growth indicated linear growth until August leveling-off afterwards. 0-group plaice reached a lower mean size (5–6 cm) at the end of the growing season than in temperate areas probably due to later settlement timing in combination with lower summer–autumn water temperatures. The comparison of observed growth rates with predictions of maximum growth models indicated a similar pattern as observed in temperate nursery grounds: Growth appeared to be maximal except for the period after summer. Whether or not this was related to changes in food quality throughout the season, to interspecies competition or to emigration remains to be elucidated.
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low effective population size and evidence for inbreeding in an overexploited flatfish plaice Pleuronectes Platessa l
Proceedings of The Royal Society B: Biological Sciences, 2005Co-Authors: Galice Hoarau, Henk W Van Der Veer, A D Rijnsdorp, Jonbjorn Palsson, Eva E Boon, Dorris N Jongma, Steven Ferber, Wytze T Stam, Jeanine L OlsenAbstract:Overexploitation and subsequent collapse of major worldwide fisheries has made it clear that marine stocks are not inexhaustible. Unfortunately, the perception remains that marine fishes are resilient to large population reductions, as even a commercially 'collapsed' stock will still consist of millions of individuals. Coupled with this notion is the idea that fisheries can, therefore, have little effect on the genetic diversity of stocks. We used DNA from archived otoliths collected between 1924 and 1972 together with 2002 juvenile's tissue to estimate effective population size (Ne) in plaice (Pleuronectes Platessa). Ne was estimated at 20 000 in the North Sea and 2000 in Iceland. These values are five orders of magnitude smaller than the estimated census size for the two locations. Populations examined between 1924 and 1960 were in Hardy-Weinberg equilibrium, whereas populations examined after approximately 1970 were not. Extensive testing was performed to rule out genotyping artefacts and Wahlund effects. The significant heterozygote deficiencies found from 1970 onward were attributed to inbreeding. The emergence of inbreeding between 1950 and 1970 coincides with the increase in fishing mortality after World War II. Although the biological mechanisms remain speculative, our demonstration of inbreeding signals the need for understanding the social and mating behaviour in commercially important fishes.
