Seasonal dynamics in pelagic fish abundance in a Baltic Sea coastal area

Axenrot, Thomas; Hansson, Sture

doi:10.1016/j.ecss.2004.02.004

Cited by 25 publications

(18 citation statements)

References 27 publications

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“…When both feeding conditions [83] and predation pressures [84], [85] are variable over the season in a fairly predictable manner, it is reasonable to suggest that a flexible behavior would be more adaptive than a genetically fixed trait adapted to a specific set of conditions [86], [87]. Development and application of microsatellite markers would provide a better power and resolution than mtDNA for analyzing the genetic component in mysid migratory behavior [88].…”

Section: Discussionmentioning

confidence: 99%

Behavioral, Ecological and Genetic Differentiation in an Open Environment—A Study of a Mysid Population in the Baltic Sea

et al. 2013

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Diel vertical migration (DVM) is often assumed to encompass an entire population. However, bimodal nighttime vertical distributions have been observed in various taxa. Mysid shrimp populations also display this pattern with one group concentrated in the pelagia and the other near the bottom. This may indicate alternative migratory strategies, resembling the seasonal partial migrations seen in birds, fishes and amphibians, where only a subset of the population migrates. To assess the persistence of these alternative strategies, we analyzed the nitrogen and carbon stable isotope signatures (as proxies for diet), biochemical indices (as proxies for growth condition), and genetic population divergence in the Baltic mysid Mysis salemaai collected at night in the pelagia and close to the bottom. Stable isotope signatures were significantly different between migrants (pelagic samples) and residents (benthic samples), indicating persistent diet differences, with pelagic mysids having a more uniform and carnivorous diet. Sequencing of the mitochondrial cytochrome subunit I (COI) gene showed genetic differentiation attributable to geographic location but not between benthic and pelagic groups. Divergent migration strategies were however supported by significantly lower gene flow between benthic populations indicating that these groups have a lower predisposition for horizontal migrations compared to pelagic ones. Different migration strategies did not convey measurable growth benefits as pelagic and benthic mysids had similar growth condition indices. Thus, the combination of ecological, biochemical and genetic markers indicate that this partial migration may be a plastic behavioral trait that yields equal growth benefits.

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Section: Discussionmentioning

confidence: 99%

Behavioral, Ecological and Genetic Differentiation in an Open Environment—A Study of a Mysid Population in the Baltic Sea

et al. 2013

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“…In 1997, C. pengoi was first found in the area (Gorokhova et al 2000), where abundances are usually higher than in neighbouring coastal and offshore waters (personal observations). The bay is a spawning and nursery area for many fish species, including herring (Axenrot and Hansson 2004). …”

Section: Methodsmentioning

confidence: 99%

Stable isotopes show food web changes after invasion by the predatory cladoceran Cercopagis pengoi in a Baltic Sea bay

et al. 2005

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Cercopagis pengoi, a recent invader to the Baltic Sea and the Laurentian Great Lakes, is a potential competitor with fish for zooplankton prey. We used stable C and N isotope ratios to elucidate trophic relationships between C. pengoi, zooplankton (microzooplankton, 90-200 microm, mostly copepod nauplii and rotifers; mesozooplankton, >200 microm, mostly copepods), and zooplanktivorous fish (herring, size range 5-15 cm and sprat, 9-11 cm) in a coastal area of the northern Baltic Sea. The isotope ratios in C. pengoi and fish were much higher than those of zooplankton, showing general trends of enrichment with trophic level. Young-of-the-year (YOY) herring had a significantly higher (15)N/(14)N ratio than C. pengoi, suggesting of a trophic linkage between the two species. To evaluate the possible relative importance of different food sources for C. pengoi and YOY herring, two-source isotope-mixing models for N were used, with micro- and mesozooplankton as prey for C. pengoi and mesozooplankton and C. pengoi as prey for YOY herring. These models indicate that mesozooplankton was the major food source of both species. However, microzooplankton may be important prey for young stages of C. pengoi. Comparative analyses of the herring trophic position before and after the invasion by C. pengoi showed a trophic level shift from 2.6 to 3.4, indicating substantial alterations in the food web structure. Our findings contribute to a growing body of evidence, showing that C. pengoi can modify food webs and trophic interactions in invaded ecosystems.

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“…The size distributions of the dominant species caught in the pelagic nets were not significantly different from those of the benthic net catches, except for small pelagic roach in a few lakes, and for salmonid populations when they were predominantly pelagic, or instance whitefish in Lake Aiguebelette. The presence of these populations in the pelagic zone can be assessed better by hydroacoustic surveys, because of the selectivity bias that generally occurs with passive gears for younger fish (Mehner and Schulz, 2002;Axenrot and Hansson, 2004). For most lakes, the inclusion of the pelagic nets did not affect the characterization of the fish communities, because the number of individual fish caught in the benthic nets was high enough to define the size structures of the dominant species, as well as of salmonids.…”

Section: Figure 1 Mean Total Estimates Of Weight (Wpue ± Std) and Nummentioning

confidence: 99%

Assessment of the pelagic fish populations using CEN multi-mesh gillnets: consequences for the characterization of the fish communities

Deceliere-Vergès¹,

Guillard²

2008

Knowl. Managt. Aquatic Ecosyst.

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The contribution of CEN standard pelagic nets to the assessment of fish communities is tested by comparing three metrics (species composition, species abundance, and size structures) measured in accordance with the standard (i.e. using benthic nets only) to those calculated from the total effort (i.e. including pelagic nets). Hydroacoustic surveys were used simultaneously to assess fish densities in the pelagic habitat. The results show that in most cases the pelagic nets did not provide any extra information about these three metrics. However, their inclusion in the calculation of CPUE and size structures may affect the picture of the fish communities, especially in lakes containing salmonid populations. This study highlights the need to sample pelagic fish when assessing fish communities in order to determine lake quality. RÉSUMÉ L'évaluation des populations de poissons pélagiques par les filets multi-mailles CEN : conséquences pour la caractérisation du peuplement La contribution des filets pélagiques du standard CEN dans l'évaluation des peuplements piscicoles est testée en comparant les métriques (composition et abondance spécifiques, structures en tailles) mesurées conformément au standard (i.e. les filets benthiques seuls), à celles issues de l'effort total (i.e. incluant les filets pélagiques). L'hydroacoustique a été utilisée simultanément pour évaluer les densités de poissons dans l'habitat pélagique. Les résultats montrent que dans la plupart des cas, les filets pélagiques n'apportent pas d'informations supplémen-taires sur les trois métriques. Toutefois, leur intégration dans le calcul des CPUE et des structures en tailles peut modifier l'image des peuplements notamment dans les lacs à salmonidés. Ce travail met en évidence la nécessité d'échantillonner les poissons pélagiques pour l'évaluation des peuplements en vue de définir la qualité du milieu.(1) ASCONIT Consultants, 6-8 Espace Henry Vallée,

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Seasonal dynamics in pelagic fish abundance in a Baltic Sea coastal area

Cited by 25 publications

References 27 publications

Behavioral, Ecological and Genetic Differentiation in an Open Environment—A Study of a Mysid Population in the Baltic Sea

Behavioral, Ecological and Genetic Differentiation in an Open Environment—A Study of a Mysid Population in the Baltic Sea

Stable isotopes show food web changes after invasion by the predatory cladoceran Cercopagis pengoi in a Baltic Sea bay

Assessment of the pelagic fish populations using CEN multi-mesh gillnets: consequences for the characterization of the fish communities

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