Salinity effects on egg production, hatching, and survival of Eurytemora affinis (Copepoda, Calanoida)

The marine survival of tagged sea trout (Salmo trutta trutta) smolt groups (n = 236) stocked from 1970 to 2001 in the Baltic Sea was analysed using a linear mixed model. The response variable, survival rate, was associated with smolt size, release date, sea surface temperature in May, and prey fish abundance, and interactions among these factors. The effect of smolt size was in interaction with Baltic herring (Clupea harengus membras) abundance; smolt size had an optimum of about 22 cm in years when herring were abundant, but when herring were less abundant, the survival of larger smolts was higher. Early stocking in warm springs or late stocking in cold springs gave the best survival rates for trout. Changes in return activity or fishing methods have made tag returns a less reliable way of estimating survival during the last 30 years. The actual return rate of undersized fish (<40 cm) compared with their estimated proportion among captured fish decreased over time, which suggests that the survival rate for the later years was probably underestimated. It is likely that we were unable to include all the relevant explanatory variables in the model, as year effects remained significant, suggesting unknown annual variation affecting survival.

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Peer Review #1 of "Size matters: relationships between body size and body mass of common coastal, aquatic invertebrates in the Baltic Sea (v0.1)"

10.7287/peerj.2906v0.1/reviews/1 ◽

2017 ◽

Keyword(s):

Body Size ◽

Baltic Sea ◽

Peer Review ◽

Body Mass ◽

Aquatic Invertebrates ◽

The Baltic Sea ◽

The Baltic

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Size matters: relationships between body size and body mass of common coastal, aquatic invertebrates in the Baltic Sea

PeerJ ◽

10.7717/peerj.2906 ◽

2017 ◽

Vol 5 ◽

pp. e2906 ◽

Cited By ~ 16

Author(s):

Johan Eklöf ◽

Åsa Austin ◽

Ulf Bergström ◽

Serena Donadi ◽

Britas D.H.K. Eriksson ◽

...

Keyword(s):

Body Size ◽

Baltic Sea ◽

Body Mass ◽

Dry Mass ◽

Negative Influence ◽

Biologically Active ◽

Relative Mass ◽

Potential Influence ◽

The Baltic Sea ◽

The Baltic

Background Organism biomass is one of the most important variables in ecological studies, making biomass estimations one of the most common laboratory tasks. Biomass of small macroinvertebrates is usually estimated as dry mass or ash-free dry mass (hereafter ‘DM’ vs. ‘AFDM’) per sample; a laborious and time consuming process, that often can be speeded up using easily measured and reliable proxy variables like body size or wet (fresh) mass. Another common way of estimating AFDM (one of the most accurate but also time-consuming estimates of biologically active tissue mass) is the use of AFDM/DM ratios as conversion factors. So far, however, these ratios typically ignore the possibility that the relative mass of biologically active vs. non-active support tissue (e.g., protective exoskeleton or shell)—and therefore, also AFDM/DM ratios—may change with body size, as previously shown for taxa like spiders, vertebrates and trees. Methods We collected aquatic, epibenthic macroinvertebrates (>1 mm) in 32 shallow bays along a 360 km stretch of the Swedish coast along the Baltic Sea; one of the largest brackish water bodies on Earth. We then estimated statistical relationships between the body size (length or height in mm), body dry mass and ash-free dry mass for 14 of the most common taxa; five gastropods, three bivalves, three crustaceans and three insect larvae. Finally, we statistically estimated the potential influence of body size on the AFDM/DM ratio per taxon. Results For most taxa, non-linear regression models describing the power relationship between body size and (i) DM and (ii) AFDM fit the data well (as indicated by low SE and high R2). Moreover, for more than half of the taxa studied (including the vast majority of the shelled molluscs), body size had a negative influence on organism AFDM/DM ratios. Discussion The good fit of the modelled power relationships suggests that the constants reported here can be used to quickly estimate organism dry- and ash-free dry mass based on body size, thereby freeing up considerable work resources. However, the considerable differences in constants between taxa emphasize the need for taxon-specific relationships, and the potential dangers associated with ignoring body size. The negative influence of body size on the AFDM/DM ratio found in a majority of the molluscs could be caused by increasingly thicker shells with organism age, and/or spawning-induced loss of biologically active tissue in adults. Consequently, future studies utilizing AFDM/DM (and presumably also AFDM/wet mass) ratios should carefully assess the potential influence of body size to ensure more reliable estimates of organism body mass.

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Body size and reproductive traits of Palaemon elegans Rathke, 1837 (Crustacea, Decapoda), a recent colonizer of the Baltic Sea

Oceanological and Hydrobiological Studies ◽

10.2478/v10009-010-0016-6 ◽

2010 ◽

Vol 39 (2) ◽

Cited By ~ 5

Author(s):

Urszula Janas ◽

Anna Mańkucka

Keyword(s):

Body Size ◽

Baltic Sea ◽

Reproductive Traits ◽

The Baltic Sea ◽

Palaemon Elegans ◽

Southern Baltic ◽

The Baltic

Body size and reproductive traits ofis a species of prawn new (since 2000) to the southern Baltic. The aim of this study was to find out whether there are differences in the sizes of individuals and in the reproductive traits of

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Investigating interdecadal salinity changes in the Baltic Sea in a 1850–2008 hindcast simulation

Climate of the Past ◽

10.5194/cp-16-1617-2020 ◽

2020 ◽

Vol 16 (4) ◽

pp. 1617-1642 ◽

Cited By ~ 1

Author(s):

Hagen Radtke ◽

Sandra-Esther Brunnabend ◽

Ulf Gräwe ◽

H. E. Markus Meier

Keyword(s):

Baltic Sea ◽

River Runoff ◽

Sea Water ◽

Salt Water ◽

Salinity Range ◽

Historical Period ◽

The Baltic Sea ◽

High Salinity Water ◽

Salinity Changes ◽

The Baltic

Abstract. Interdecadal variability in the salinity of the Baltic Sea is dominated by a 30-year cycle with a peak-to-peak amplitude of around 0.4 g kg−1 at the surface. Such changes may have substantial consequences for the ecosystem, since species are adapted to a suitable salinity range and may experience habitat shifts. It is therefore important to understand the drivers of such changes. We use both analysis of empirical data and a numerical model reconstruction for the period of 1850–2008 to explain these interdecadal changes. The model explains 93 % and 52 % of the variance in the observed interdecadal salinity changes at the surface and the bottom, respectively, at an oceanographic station at Gotland Deep. It is known that the 30-year periodicity coincides with a variability in river runoff. Periods of enhanced runoff are followed by lower salinities. We demonstrate, however, that the drop in mean salinity cannot be understood as a simple dilution of the Baltic Sea water by freshwater. Rather, the 30-year periodicity in river runoff occurs synchronously with a substantial variation in salt water import across Darss Sill. Fewer strong inflow events occur in periods of enhanced river runoff. This reduction in the import of high-salinity water is the main reason for the freshening of the water below the permanent halocline. In the bottom waters, the variation in salinity is larger than at the surface. As a consequence, the surface layer salinity variation is caused by a combination of both effects: a direct dilution by river water and a reduced upward diffusion of salt as a consequence of reduced inflow activity. Our findings suggest that the direct dilution effect is responsible for 27 % of the salinity variations only. It remains unclear whether the covariation in river runoff and inflow activity are only a coincidental correlation during the historical period or whether a mechanistic link exists between the two quantities, e.g. whether both are caused by the same atmospheric patterns.

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Size matters: relationships between body size, dry weight and ash-free dry weight of common coastal, aquatic invertebrates in the Baltic Sea

10.7287/peerj.preprints.2368v1 ◽

2016 ◽

Author(s):

Johan Eklöf ◽

Åsa Austin ◽

Ulf Bergström ◽

Serena Donadi ◽

Britas D H K Eriksson ◽

...

Keyword(s):

Body Size ◽

Baltic Sea ◽

Dry Weight ◽

Negative Influence ◽

The Body ◽

Biologically Active ◽

Power Relationship ◽

Potential Influence ◽

The Baltic Sea ◽

The Baltic

Background. Organism biomass is one of the most important variables in ecological studies, making estimations of organism weight one of the most common laboratory tasks. Biomass of small macroinvertebrates is usually estimated as dry (DW) or ash-free dry weight (AFDW); a laborious and time consuming process, that often can be speeded up using easily measured and reliable proxy variables like wet/fresh weight and/or body size. Another common way of estimating AFDW - which is the most accurate but also time-consuming estimate of biologically active tissue weight - is the use of AFDW/DW ratios or conversion factors. So far, however, these ratios typically ignore the possibility that the relative weight of biologically active vs. non-active support tissue (e.g. protective exoskeleton or shell) - and therefore, also the AFDW/DW ratio - may change with body size, as previously shown for taxa like spiders, vertebrates and trees. Methods. We collected samples of aquatic, epibenthic macroinvertebrates (>1 mm) in 32 shallow bays along a 360 km stretch of the Swedish coast along the Baltic Sea; one of the largest brackish water bodies on Earth. We then estimated statistical relationships between the body size (length or height in mm), dry weight and ash-free dry weight for 14 of the most common taxa; five gastropods, three bivalves, three crustaceans and three insect larvae. Finally, we statistically estimated the potential influence of body size on the AFDW/DW ratio per taxon. Results. For most of the taxa, non-linear regression models describing the power relationship between body size and i) DW and ii) AFDW fit the data well (as indicated by low SE and high R2). Moreover, for more than half of the taxa studied (including the vast majority of the shelled molluscs), body size had a negative influence on organism AFDW/DW ratios. Discussion. The good fit of the modelled power relationships suggest that the constants reported here can be used to more quickly estimate organism dry- and ash-free dry weight based on body size, thereby freeing up considerable work resources. However, the considerable differences in constants between taxa emphasize the need for taxon-specific relationships, and the potential dangers associated with either ignoring body size or substituting relationships between taxa. The negative influence of body size on AFDW/DW ratio found in a majority of the molluscs could be caused by increasingly thicker shells with organism age, and/or spawning-induced loss of biologically active tissue in adults. Consequently, future studies utilizing AFDW/DW (and presumably also AFDW/wet weight) ratios should carefully assess the potential influence of body size to ensure more reliable estimates of organism biomass.

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Antioxidant Responses in Copepods Are Driven Primarily by Food Intake, Not by Toxin-Producing Cyanobacteria in the Diet

Frontiers in Physiology ◽

10.3389/fphys.2021.805646 ◽

2022 ◽

Vol 12 ◽

Author(s):

Elena Gorokhova ◽

Rehab El-Shehawy

Keyword(s):

Baltic Sea ◽

Food Availability ◽

Egg Production ◽

Feeding Activity ◽

Food Type ◽

Antioxidant Enzyme Activities ◽

Growth Responses ◽

The Baltic Sea ◽

Rna Content ◽

The Baltic

The association between oxidative processes and physiological responses has received much attention in ecotoxicity assessment. In the Baltic Sea, bloom-forming cyanobacterium Nodularia spumigena is a significant producer of various bioactive compounds, and both positive and adverse effects on grazers feeding in cyanobacteria blooms are reported. To elucidate the effect mechanisms and species sensitivity to the cyanobacteria-dominating diet, we exposed two Baltic copepods, Acartia bifilosa and Eurytemora affinis, to a diet consisting of toxin-producing cyanobacteria N. spumigena and a high-quality food Rhodomonas salina at 0–300 μg C L−1; the control food was R. salina provided as a monodiet at the same food levels. The subcellular responses to food type and availability were assayed using a suite of biomarkers – antioxidant enzymes [superoxide dismutases (SOD), catalase (CAT), and glutathione S-transferases (GST)] and acetylcholinesterase (AChE). In parallel, we measured feeding activity using gut content (GC) assayed by real-time PCR analysis that quantified amounts of the prey DNA in copepod stomachs. As growth and reproduction endpoints, individual RNA content (a proxy for protein synthesis capacity), egg production rate (EPR), and egg viability (EV%) were used. In both toxic and nontoxic foods, copepod GC, RNA content, and EPR increased with food availability. Antioxidant enzyme activities increased with food availability regardless of the diet type. Moreover, CAT (both copepods), SOD, and GST (A. bifilosa) were upregulated in the copepods receiving cyanobacteria; the response was detectable when adjusted for the feeding and/or growth responses. By contrast, the diet effects were not significant when food concentration was used as a co-variable. A bimodal response in AChE was observed in A. bifilosa feeding on cyanobacteria, with up to 52% increase at the lower levels (5–25 μg C L−1) and 32% inhibition at the highest food concentrations. These findings contribute to the refinement of biomarker use for assessing environmental stress and mechanistic understanding of cyanobacteria effects in grazers. They also suggest that antioxidant and AChE responses to feeding activity and diet should be accounted for when using biomarker profiles in field-collected animals in the Baltic Sea and, perhaps other systems, where toxic cyanobacteria are common.

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Life-history responses to changing temperature and salinity of the Baltic Sea copepod Eurytemora affinis

Marine Biology ◽

10.1007/s00227-017-3279-6 ◽

2018 ◽

Vol 165 (2) ◽

Cited By ~ 7

Author(s):

Konrad Karlsson ◽

Simona Puiac ◽

Monika Winder

Keyword(s):

Life History ◽

Baltic Sea ◽

The Baltic Sea ◽

Eurytemora Affinis ◽

The Baltic

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Size matters: relationships between body size, dry weight and ash-free dry weight of common coastal, aquatic invertebrates in the Baltic Sea

10.7287/peerj.preprints.2368 ◽

2016 ◽

Author(s):

Johan Eklöf ◽

Åsa Austin ◽

Ulf Bergström ◽

Serena Donadi ◽

Britas D H K Eriksson ◽

...

Keyword(s):

Body Size ◽

Baltic Sea ◽

Dry Weight ◽

Negative Influence ◽

The Body ◽

Biologically Active ◽

Power Relationship ◽

Potential Influence ◽

The Baltic Sea ◽

The Baltic

Background. Organism biomass is one of the most important variables in ecological studies, making estimations of organism weight one of the most common laboratory tasks. Biomass of small macroinvertebrates is usually estimated as dry (DW) or ash-free dry weight (AFDW); a laborious and time consuming process, that often can be speeded up using easily measured and reliable proxy variables like wet/fresh weight and/or body size. Another common way of estimating AFDW - which is the most accurate but also time-consuming estimate of biologically active tissue weight - is the use of AFDW/DW ratios or conversion factors. So far, however, these ratios typically ignore the possibility that the relative weight of biologically active vs. non-active support tissue (e.g. protective exoskeleton or shell) - and therefore, also the AFDW/DW ratio - may change with body size, as previously shown for taxa like spiders, vertebrates and trees. Methods. We collected samples of aquatic, epibenthic macroinvertebrates (>1 mm) in 32 shallow bays along a 360 km stretch of the Swedish coast along the Baltic Sea; one of the largest brackish water bodies on Earth. We then estimated statistical relationships between the body size (length or height in mm), dry weight and ash-free dry weight for 14 of the most common taxa; five gastropods, three bivalves, three crustaceans and three insect larvae. Finally, we statistically estimated the potential influence of body size on the AFDW/DW ratio per taxon. Results. For most of the taxa, non-linear regression models describing the power relationship between body size and i) DW and ii) AFDW fit the data well (as indicated by low SE and high R2). Moreover, for more than half of the taxa studied (including the vast majority of the shelled molluscs), body size had a negative influence on organism AFDW/DW ratios. Discussion. The good fit of the modelled power relationships suggest that the constants reported here can be used to more quickly estimate organism dry- and ash-free dry weight based on body size, thereby freeing up considerable work resources. However, the considerable differences in constants between taxa emphasize the need for taxon-specific relationships, and the potential dangers associated with either ignoring body size or substituting relationships between taxa. The negative influence of body size on AFDW/DW ratio found in a majority of the molluscs could be caused by increasingly thicker shells with organism age, and/or spawning-induced loss of biologically active tissue in adults. Consequently, future studies utilizing AFDW/DW (and presumably also AFDW/wet weight) ratios should carefully assess the potential influence of body size to ensure more reliable estimates of organism biomass.

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