The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Myron A. Peck - One of the best experts on this subject based on the ideXlab platform.
-
calibrating and comparing somatic nucleic acid and otolith based indicators of growth and condition in young juvenile European Sprat Sprattus Sprattus
Journal of Experimental Marine Biology and Ecology, 2015Co-Authors: Myron A. Peck, Jens-peter Herrmann, Hannes Baumann, Catriona Clemmesen, Marta Moyano, Axel TemmingAbstract:Highlights: • Juvenile fish somatic-, biochemical- and otolith-based condition indices are compared. • RNA/DNA, otolith increments, and somatic condition explained > 70% growth variability. • Response times of proxies differ after food deprivation and re-feeding. • RNA/DNA most rapid response, otolith increments explain length but not mass growth. • Caution suggested if condition indices are applied to fish in patchy prey environments. Abstract: Reliable estimates of short- and longer-term in situ growth and condition of organisms are critical if one hopes to understand how the environment regulates survival. This study reports the first comparison of somatic- (K), biochemical- (RNA–DNA ratio, RD) and otolith- (increment widths, OIW) based indices of condition of a young juvenile fish. Measurements were made on European Sprat (Sprattus Sprattus) that had i) known differences in somatic growth rate caused by providing different, constant prey ration levels, ii) been fed ad libitum at 7, 11, 15, 18 and 22 °C, and iii) been deprived of prey for either 4, 8 or 12 days and re-fed for 8 days. All three proxies explained significant amounts (70 to 90%) of the variability in measured growth rate. In fish experiencing a change in their feeding level and concomitant change in mass-at-length (K), RD tracked changes in both length and mass while OIW only tracked changes in length. Values of OIW and RD were highest at 18 °C suggesting that this is the optimal temperature for growth in these juveniles. During food deprivation, RD and OIW rapidly decreased and reached their lowest values within ~ 4 days. Upon re-feeding, RD increased most rapidly, K was most variable and the response time in OIW was slowest (two-times slower than RD). These patterns reflected preferential allocation of food energy to restore body mass in recently re-fed fish prior to fish increasing both mass and length. These results indicate that the sensitivity and applicability of growth proxies depend on the recent feeding history, that proxies have different response times, and that caution be taken when inferring growth and condition in early life stages of fishes that forage in patchy prey environments.
-
Relationships between feeding, growth and swimming activity of European Sprat (Sprattus Sprattus L.) post-larvae in the laboratory
Environmental Biology of Fishes, 2015Co-Authors: Myron A. Peck, Bianca Ewest, Jens-peter Herrmann, Fahad A. Al-misned, M. Golam Mortuza, Sven Stäcker, Axel TemmingAbstract:Despite their trophodynamic importance in many aquatic ecosystems, few studies have quantified the feeding-growth relationship of clupeid fishes. In laboratory trials, we quantified the relationship between rates of food consumption ( C , % fish energy content (Joules d^−1)), somatic growth rate ( G, % Joules d^−1), and swimming speed ( S _S, body lengths ( bl ) s^−1) for post-larval (30- to 50-mm standard length) European Sprat ( Sprattus Sprattus L.) collected from the southwestern Baltic Sea. Measurements of G and S _S were also made on groups before and after an abrupt shift in prey availability. Maintenance (0-growth) and maximum food consumption rates were 5.5 and 42 % somatic energy content d^−1, respectively. Mean ± SE gross growth efficiency ( K _1 = 100∙ G ∙ C ^ −1 ) was 26.9 ± 3.0 %. Unfed post-larvae had markedly lower S _S compared to continuously-fed fish (0.1 versus 0.5 to 0.7 bl s^−1). After 10 days of re-feeding, one group of previously unfed fish was hyperactive (mean S _S of 1.2 bl s^−1) but no re-fed groups exhibited hyperphagia (based upon prey numbers), increased K _1, or compensatory growth. Increased competition (relatively high S _S) was evident during feeding in fish maintained at low to moderate but not at ad libitum prey levels. Our findings provide estimates of prey resources required to fuel in situ growth and help characterize metabolic strategies of European Sprat within variable feeding environments.
-
erratum to relationships between feeding growth and swimming activity of European Sprat Sprattus Sprattus l post larvae in the laboratory
Environmental Biology of Fishes, 2015Co-Authors: Myron A. Peck, Bianca Ewest, Jens-peter Herrmann, Sven Stäcker, Axel TemmingAbstract:Despite their trophodynamic importance in many aquatic ecosystems, few studies have quantified the feeding-growth relationship of clupeid fishes. In laboratory trials, we quantified the relationship between rates of food consumption (C, % fish energy content (Joules d−1)), somatic growth rate (G, % Joules d−1), and swimming speed (SS, body lengths (bl) s−1) for post-larval (30- to 50-mm standard length) European Sprat (Sprattus Sprattus L.) collected from the southwestern Baltic Sea. Measurements of G and SS were also made on groups before and after an abrupt shift in prey availability. Maintenance (0-growth) and maximum food consumption rates were 5.5 and 42 % somatic energy content d−1, respectively. Mean ± SE gross growth efficiency (K1 = 100∙G∙C−1) was 26.9 ± 3.0 %. Unfed post-larvae had markedly lower SS compared to continuously-fed fish (0.1 versus 0.5 to 0.7 bl s−1). After 10 days of re-feeding, one group of previously unfed fish was hyperactive (mean SS of 1.2 bl s−1) but no re-fed groups exhibited hyperphagia (based upon prey numbers), increased K1, or compensatory growth. Increased competition (relatively high SS) was evident during feeding in fish maintained at low to moderate but not at ad libitum prey levels. Our findings provide estimates of prey resources required to fuel in situ growth and help characterize metabolic strategies of European Sprat within variable feeding environments.
-
A Day in the Life of Fish Larvae: Modeling Foraging and Growth Using Quirks
PLOS ONE, 2014Co-Authors: Klaus B. Huebert, Myron A. PeckAbstract:This article introduces “Quirks,” a generic, individual-based model synthesizing over 40 years of empirical and theoretical insights into the foraging behavior and growth physiology of marine fish larvae. In Quirks, different types of larvae are defined by a short list of their biological traits, and all foraging and growth processes (including the effects of key environmental factors) are modeled following one unified set of mechanistic rules. This approach facilitates ecologically meaningful comparisons between different species and environments. We applied Quirks to model young exogenously feeding larvae of four species: 5.5-mm European anchovy (Engraulis encrasicolus), 7-mm Atlantic cod (Gadus morhua), 13-mm Atlantic herring (Clupea harengus), and 7-mm European Sprat (Sprattus Sprattus). Modeled growth estimates explained the majority of variability among 53 published empirical growth estimates, and displayed very little bias: 0.65%±1.2% d−1 (mean ± standard error). Prey organisms of ∼67% the maximum ingestible prey length were optimal for all larval types, in terms of the expected ingestion per encounter. Nevertheless, the foraging rate integrated over all favorable prey sizes was highest when smaller organisms made up >95% of the prey biomass under the assumption of constant normalized size spectrum slopes. The overall effect of turbulence was consistently negative, because its detrimental influence on prey pursuit success exceeded its beneficial influence on prey encounter rate. Model sensitivity to endogenous traits and exogenous environmental factors was measured and is discussed in depth. Quirks is free software and open source code is provided.
-
Reprint of: The ecophysiology of Sprattus Sprattus in the Baltic and North Seas
Progress in Oceanography, 2012Co-Authors: Myron A. Peck, Jens-peter Herrmann, Hannes Baumann, Catriona Clemmesen, Bastian Huwer, Holger Haslob, Matthias Bernreuther, Philipp Kanstinger, Fritz Köster, Christoph PetereitAbstract:The European Sprat (Sprattus Sprattus) was a main target species of the German GLOBEC program that investigated the trophodynamic structure and function of the Baltic and North Seas under the influence of physical forcing. This review summarizes literature on the ecophysiology of Sprat with an emphasis on describing how environmental factors influence the life-history strategy of this small pelagic fish. Ontogenetic changes in feeding and growth, and the impacts of abiotic and biotic factors on vital rates are discussed with particular emphasis on the role of temperature as a constraint to life-history scheduling of this species in the Baltic Sea. A combination of field and laboratory data suggests that optimal thermal windows for growth and survival change during early life and are wider for eggs (5–17 °C) than in young (8- to 12-mm) early feeding larvae (5–12 °C). As larvae become able to successfully capture larger prey, thermal windows expand to include warmer waters. For example, 12- to 16-mm larvae can grow well at 16 °C and larger, transitional-larvae and early juveniles display the highest rates of feeding and growth at ~18–22 °C. Gaps in knowledge are identified including the need for additional laboratory studies on the physiology and behavior of larvae (studies that will be particularly critical for biophysical modeling activities) and research addressing the role of overwinter survival as a factor shaping phenology and setting limits on the productivity of this species in areas located at the northern limits of its latitudinal range (such as the Baltic Sea). Based on stage- and temperature-specific mortality and growth potential of early life stages, our analysis suggests that young-of-the year Sprat would benefit from inhabiting warmer, near-shore environments rather than the deeper-water spawning grounds such as the Bornholm Basin (central Baltic Sea). Utilization of warmer, nearshore waters (or a general increase in Baltic Sea temperatures) is expected to accelerate growth rates but also enhance the possibility for density-dependent regulation of recruitment (e.g., top-down control of zooplankton resources) acting during the late-larval and juvenile stages, particularly when Sprat stocks are at high levels.
Reinhold Hanel - One of the best experts on this subject based on the ideXlab platform.
-
mitochondrial phylogeography of the European Sprat Sprattus Sprattus l clupeidae reveals isolated climatically vulnerable populations in the mediterranean sea and range expansion in the northeast atlantic
Molecular Ecology, 2008Co-Authors: Paul Debes, Frank E Zachos, Reinhold HanelAbstract:We examined the genetic structure of the European Sprat (Sprattus Sprattus) by means of a 530-bp sequence of the mitochondrial control region from 210 fish originating from seven sampling localities of its distributional range. Phylogeographical analysis of 128 haplotypes showed a phylogenetic separation into two major clades with the Strait of Sicily acting as a barrier to gene flow between them. While no population differentiation was observed based on analysis of molecular variance and net nucleotide differences between samples of the Baltic Sea, the North Sea and the Bay of Biscay nor between the Black Sea and the Bosporus, a strong population differentiation between these samples and two samples from the Mediterranean Sea was found. Further, the biggest genetic distance was observed within the Mediterranean Sea between the populations of the Gulf of Lyon and the Adriatic Sea, indicating genetic isolation of these regions. Low genetic diversities and star-like haplotype networks of both Mediterranean Sea populations point towards recent demographic expansion scenarios after low population size, which is further supported by negative FS values and unimodal mismatch distributions with a low mean. Along the northeast Atlantic coast, a northwards range expansion of a large and stable population can be assumed. The history of a diverse but differentiated Black Sea population remains unknown due to uncertainties in the palaeo-oceanography of this sea. Our genetic data did not confirm the presently used classification into subspecies but are only preliminary in the absence of nuclear genetic analyses.
Axel Temming - One of the best experts on this subject based on the ideXlab platform.
-
calibrating and comparing somatic nucleic acid and otolith based indicators of growth and condition in young juvenile European Sprat Sprattus Sprattus
Journal of Experimental Marine Biology and Ecology, 2015Co-Authors: Myron A. Peck, Jens-peter Herrmann, Hannes Baumann, Catriona Clemmesen, Marta Moyano, Axel TemmingAbstract:Highlights: • Juvenile fish somatic-, biochemical- and otolith-based condition indices are compared. • RNA/DNA, otolith increments, and somatic condition explained > 70% growth variability. • Response times of proxies differ after food deprivation and re-feeding. • RNA/DNA most rapid response, otolith increments explain length but not mass growth. • Caution suggested if condition indices are applied to fish in patchy prey environments. Abstract: Reliable estimates of short- and longer-term in situ growth and condition of organisms are critical if one hopes to understand how the environment regulates survival. This study reports the first comparison of somatic- (K), biochemical- (RNA–DNA ratio, RD) and otolith- (increment widths, OIW) based indices of condition of a young juvenile fish. Measurements were made on European Sprat (Sprattus Sprattus) that had i) known differences in somatic growth rate caused by providing different, constant prey ration levels, ii) been fed ad libitum at 7, 11, 15, 18 and 22 °C, and iii) been deprived of prey for either 4, 8 or 12 days and re-fed for 8 days. All three proxies explained significant amounts (70 to 90%) of the variability in measured growth rate. In fish experiencing a change in their feeding level and concomitant change in mass-at-length (K), RD tracked changes in both length and mass while OIW only tracked changes in length. Values of OIW and RD were highest at 18 °C suggesting that this is the optimal temperature for growth in these juveniles. During food deprivation, RD and OIW rapidly decreased and reached their lowest values within ~ 4 days. Upon re-feeding, RD increased most rapidly, K was most variable and the response time in OIW was slowest (two-times slower than RD). These patterns reflected preferential allocation of food energy to restore body mass in recently re-fed fish prior to fish increasing both mass and length. These results indicate that the sensitivity and applicability of growth proxies depend on the recent feeding history, that proxies have different response times, and that caution be taken when inferring growth and condition in early life stages of fishes that forage in patchy prey environments.
-
Relationships between feeding, growth and swimming activity of European Sprat (Sprattus Sprattus L.) post-larvae in the laboratory
Environmental Biology of Fishes, 2015Co-Authors: Myron A. Peck, Bianca Ewest, Jens-peter Herrmann, Fahad A. Al-misned, M. Golam Mortuza, Sven Stäcker, Axel TemmingAbstract:Despite their trophodynamic importance in many aquatic ecosystems, few studies have quantified the feeding-growth relationship of clupeid fishes. In laboratory trials, we quantified the relationship between rates of food consumption ( C , % fish energy content (Joules d^−1)), somatic growth rate ( G, % Joules d^−1), and swimming speed ( S _S, body lengths ( bl ) s^−1) for post-larval (30- to 50-mm standard length) European Sprat ( Sprattus Sprattus L.) collected from the southwestern Baltic Sea. Measurements of G and S _S were also made on groups before and after an abrupt shift in prey availability. Maintenance (0-growth) and maximum food consumption rates were 5.5 and 42 % somatic energy content d^−1, respectively. Mean ± SE gross growth efficiency ( K _1 = 100∙ G ∙ C ^ −1 ) was 26.9 ± 3.0 %. Unfed post-larvae had markedly lower S _S compared to continuously-fed fish (0.1 versus 0.5 to 0.7 bl s^−1). After 10 days of re-feeding, one group of previously unfed fish was hyperactive (mean S _S of 1.2 bl s^−1) but no re-fed groups exhibited hyperphagia (based upon prey numbers), increased K _1, or compensatory growth. Increased competition (relatively high S _S) was evident during feeding in fish maintained at low to moderate but not at ad libitum prey levels. Our findings provide estimates of prey resources required to fuel in situ growth and help characterize metabolic strategies of European Sprat within variable feeding environments.
-
erratum to relationships between feeding growth and swimming activity of European Sprat Sprattus Sprattus l post larvae in the laboratory
Environmental Biology of Fishes, 2015Co-Authors: Myron A. Peck, Bianca Ewest, Jens-peter Herrmann, Sven Stäcker, Axel TemmingAbstract:Despite their trophodynamic importance in many aquatic ecosystems, few studies have quantified the feeding-growth relationship of clupeid fishes. In laboratory trials, we quantified the relationship between rates of food consumption (C, % fish energy content (Joules d−1)), somatic growth rate (G, % Joules d−1), and swimming speed (SS, body lengths (bl) s−1) for post-larval (30- to 50-mm standard length) European Sprat (Sprattus Sprattus L.) collected from the southwestern Baltic Sea. Measurements of G and SS were also made on groups before and after an abrupt shift in prey availability. Maintenance (0-growth) and maximum food consumption rates were 5.5 and 42 % somatic energy content d−1, respectively. Mean ± SE gross growth efficiency (K1 = 100∙G∙C−1) was 26.9 ± 3.0 %. Unfed post-larvae had markedly lower SS compared to continuously-fed fish (0.1 versus 0.5 to 0.7 bl s−1). After 10 days of re-feeding, one group of previously unfed fish was hyperactive (mean SS of 1.2 bl s−1) but no re-fed groups exhibited hyperphagia (based upon prey numbers), increased K1, or compensatory growth. Increased competition (relatively high SS) was evident during feeding in fish maintained at low to moderate but not at ad libitum prey levels. Our findings provide estimates of prey resources required to fuel in situ growth and help characterize metabolic strategies of European Sprat within variable feeding environments.
Dorte Bekkevold - One of the best experts on this subject based on the ideXlab platform.
-
genetic population structure of European Sprat Sprattus Sprattus differentiation across a steep environmental gradient in a small pelagic fish
Marine Ecology Progress Series, 2009Co-Authors: Morten T Limborg, Jes S Pedersen, Jakob Hemmerhansen, Jonna Tomkiewicz, Dorte BekkevoldAbstract:Factors such as oceanographic retention, isolation by distance and secondary contact zones have, among others, been suggested to explain the low, but statistically significant, neutral pop- ulation structure observed in many marine fishes. European Sprat Sprattus Sprattus L. is not known to display philopatric spawning behaviour or to exhibit local retention of eggs and larvae. It thus consti- tutes a good model for studying population structure in a characteristic small pelagic fish with high dis- persal potential and an opportunistic life history. We analysed 931 specimens of Sprat from 9 spawning locations in and around the North Sea and Baltic Sea area and from a geographically distant popula- tion from the Adriatic Sea. Analyses of 9 microsatellite loci revealed a sharp genetic division separat- ing samples from the northeastern Atlantic Ocean and the Baltic Sea (pairwise θ = 0.019 to 0.035), con- curring with a steep salinity gradient. We found, at most, weak structure among samples within the northeastern Atlantic region and within the Baltic Sea (pairwise θ = 0.001 to 0.009). The Adriatic Sea population was highly differentiated from all northern samples (pairwise θ = 0.071 to 0.092). Overall, the observed population structure resembles that of most other marine fishes studied in the North and Baltic Sea areas. Nevertheless, spatially explicit differences are observed among species, probably reflecting specific life histories. Such fine-scale population structures should be taken into account when considering complex ecosystem functions, e.g. in multispecies stock management.
D Bekkevold - One of the best experts on this subject based on the ideXlab platform.
-
Imprints from genetic drift and mutation imply relative divergence times across marine transition zones in a pan-European small pelagic fish (Sprattus Sprattus)
Heredity, 2012Co-Authors: M T Limborg, R Hanel, P V Debes, A K Ring, C André, C S Tsigenopoulos, D BekkevoldAbstract:Geographic distributions of most temperate marine fishes are affected by postglacial recolonisation events, which have left complex genetic imprints on populations of marine species. This study investigated population structure and demographic history of European Sprat ( Sprattus Sprattus L.) by combining inference from both mtDNA and microsatellite genetic markers throughout the species' distribution. We compared effects from genetic drift and mutation for both genetic markers in shaping genetic differentiation across four transition zones. Microsatellite markers revealed significant isolation by distance and a complex population structure across the species′ distribution (overall θ _ST=0.038, P
