Influence of environmental conditions, population density, and prey type on the lipid content in Baltic herring (Clupea harengus membras) from the northern Baltic Sea

2019 ◽  
Vol 76 (4) ◽  
pp. 576-585 ◽  
Author(s):  
Marjut Rajasilta ◽  
Jari Hänninen ◽  
Lea Laaksonen ◽  
Päivi Laine ◽  
Jukka-Pekka Suomela ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Lipid Content ◽  
Sea Water ◽  
Energy Content ◽  
Global Climate ◽  
Clupea Harengus ◽  
Composition Analysis ◽  
Baltic Herring ◽  
The Baltic

Global climate change can affect the energy content of fish by altering their lipid physiology and consumption. We investigated the effects of different environmental stressors on the lipid content of the Baltic herring (Clupea harengus membras) from spawning ground samples that were collected annually in the northern Baltic Sea. During 1987–2014, the average lipid content of herring muscle decreased from 5%–6% (wet mass) to 1.5% (wet mass). Generalized linear mixed models indicated that sea water salinity and the size of the herring stock explained best the declining trend of lipid content. We estimated that the amount of the lipid storage incorporated in the spawning stock decreased by approximately 45% during the study, with respective energy content decreases. Fatty acid composition analysis revealed that herring lipids contained a high proportion of EPA (eicosapentaenoic acid; 20:5n-3) and DHA (docosahexaenoic acid; 22:6n-3), which likely originated from its main summertime prey, Limnocalanus macrurus. The results illustrate various climate change-induced processes leading to changes in the lipid content of the Baltic herring and, consequently, to changes in the energy flows of the northern Baltic ecosystem.

Anthropogenic and naturally produced brominated substances in Baltic herring (Clupea harengus membras) from two sites in the Baltic Sea

Chemosphere ◽  
2016 ◽  
Vol 144 ◽  
pp. 2408-2414 ◽  
Author(s):  
Anna-Karin Dahlberg ◽  
Anders Bignert ◽  
Jessica Legradi ◽  
Juliette Legler ◽  
Lillemor Asplund
Keyword(s):  
Baltic Sea ◽  
Clupea Harengus ◽  
The Baltic Sea ◽  
Baltic Herring ◽  
The Baltic

scholarly journals Morphological abnormalities in gonads of the Baltic herring (Clupea harengus membras): Description of types and prevalence in the northern Baltic Sea

AMBIO ◽  
2015 ◽  
Vol 45 (2) ◽  
pp. 205-214
Author(s):  
Marjut Rajasilta ◽  
Mikael Elfving ◽  
Jari Hänninen ◽  
Päivi Laine ◽  
Ilppo Vuorinen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Clupea Harengus ◽  
Morphological Abnormalities ◽  
Baltic Herring ◽  
The Baltic

Effects of Climate Change and Fisheries on the Marine Ecosystem of the Baltic Sea

2019 ◽  
Author(s):  
Christian Möllmann
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Regime Shift ◽  
Sea Water ◽  
Marine Ecosystem ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
The Baltic Sea ◽  
Recruitment Failure ◽  
The Baltic

Climate change and fisheries have significantly changed the Baltic Sea ecosystem, with the demise of Eastern Baltic cod (Gadus morhua callarias) being the signature development. Cod in the Central Baltic Sea collapsed in the late 1980s as a result of low reproductive success and overfishing. Low recruitment and hence small year-classes were not able to compensate for fishing pressures far above sustainable levels. Recruitment failure can be mainly related to the absence of North Sea water inflows to the Central Baltic deep basins. These major Baltic inflows (MBIs) occurred regularly until the 1980s, when their frequency decreased to a decadal pattern, a development attributed to changes in atmospheric circulation patterns. MBIs are needed for ventilation of otherwise stagnating Baltic deep waters, and their absence caused reduced oxygen and salinity levels in cod-spawning habitats, limiting egg and larval survival. Climate change, on the other hand, has promoted a warmer environment richer in zooplanktonic food for larval Baltic sprat (Sprattus sprattus). Resulting large year-classes and low predation by the collapsed cod stock caused an outburst of the sprat stock that cascaded down to the zoo- and phytoplankton trophic levels. Furthermore, a large sprat population controlled cod recruitment and hence hindered a recovery of the stock by predation on cod eggs, limiting cod larval food supply. The change in ecosystem structure and function caused by the collapse of the cod stock was a major part and driver of an ecosystem regime shift in the Central Baltic Sea during the period 1988 to 1993. This reorganization of ecosystem structure involved all trophic levels from piscivorous and planktivorous fish to zoo- and phytoplankton. The observed large-scale ecosystem changes displayed the characteristics of a discontinuous regime shift, initiated by climate-induced changes in the abiotic environment and stabilized by feedback loops in the food web. Discontinuous changes such as regime shifts are characteristically difficult to reverse, and the Baltic ecosystem recently rather shows signs of increasing ecological novelty for which the failed recovery of the cod stock despite a reduction in fishing pressure is a clear symptom. Unusually widespread deficient oxygen conditions in major cod-spawning areas have altered the overall productivity of the population by negatively affecting growth and recruitment. Eutrophication as a consequence of intensive agriculture is the main driver for anoxia in the Baltic Sea amplified by the effects on continuing climate change and stabilized by self-enforcing feedbacks. Developing ecological novelty in the Baltic Sea hence requires true cross-sectoral ecosystem-based management approaches that truly integrate eutrophication combatment, species conservation, and living resources management.

Representative climate projections for the North Sea and Baltic Sea

2021 ◽  
Author(s):  
Christian Dieterich ◽  
Matthias Gröger ◽  
Anders Höglund ◽  
Renate A. I. Wilcke ◽  
H. E. Markus Meier
Keyword(s):  
Climate Change ◽  
Model Selection ◽  
Baltic Sea ◽  
Model Uncertainty ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Models ◽  
Climate Projections ◽  
The Baltic Sea ◽  
The Baltic

<p>Robust estimations of uncertainty for climate projections on the regional scale are highly needed but are still challenging. Regional climate projections rely on downscaling global climate scenarios. Typically, a number of different global climate models are downscaled to assess the inherent model uncertainty. The more models, the more robust the estimate of model uncertainty. However, this strategy is time consuming and so ensembles of regional projections are usually smaller than ensembles of global projections which can lead to an underestimation of regional uncertainty. With an increasing number of available global projections regional downscaling becomes increasingly expensive. We use a regional ensemble of coupled atmosphere-ice-ocean scenarios and a ensemble of ocean-ecosystem scenarios for the Baltic Sea to explore the effect of model selection on the representation of model uncertainty. Using a number of climate indices to characterize the regional system we apply a model selection that is representative of the original ensemble in terms of ensemble spread. We use existing algorithms to generate orthogonal patterns of climate change for the Baltic Sea. A small number of patterns is used to represent the climate change and its uncertainty in physical and biogeochemical parameters of the Baltic Sea. We show that climate change signals in atmosphere, ocean and ecosystem are coherent and that atmospheric or oceanic indices can be used to select global climate models for an ensemble of representative regional ecosystem scenarios for the Baltic Sea. Since the atmospheric climate in the regional climate model is close to its representation in the global climate model that latter can be used to perform an initial model selection.</p>

scholarly journals Forage fish quality: seasonal lipid dynamics of herring (Clupea harengus L.) and sprat (Sprattus sprattus L.) in the Baltic Sea

2013 ◽  
Vol 71 (1) ◽  
pp. 56-71 ◽  
Author(s):  
Maria C. Røjbek ◽  
Jonna Tomkiewicz ◽  
Charlotte Jacobsen ◽  
Josianne G. Støttrup
Keyword(s):  
Fatty Acids ◽  
Baltic Sea ◽  
Lipid Content ◽  
Clupea Harengus ◽  
Forage Fish ◽  
The Baltic Sea ◽  
Sprattus Sprattus ◽  
Fish Size ◽  
Lipid Dynamics ◽  
The Baltic

Abstract Røjbek, M. C., Tomkiewicz, J., Jacobsen, C., and Støttrup, J. G. Forage fish quality: seasonal lipid dynamics of herring (Clupea harengus L.) and sprat (Sprattus sprattus L.) in the Baltic Sea. – ICES Journal of Marine Science, 71: . This study investigates lipid content and fatty acid composition of two important forage fish, sprat (Sprattus sprattus) and herring (Clupea harengus) in the Baltic Sea ecosystem. Seasonal variation in lipids was studied during three periods following the annual reproductive cycle considering potential differences relating to fish size, sex, and reproductive status. The isopod Saduria entomon, being at times an important prey for predatory fish, was included for comparison. In both sprat and herring, lipid content and absolute contents of essential polyunsaturated fatty acids (PUFAs) varied seasonally with high levels towards the end of the annual zooplankton production cycle, succeeded by a decline. Lipid content and fatty acid composition differed significantly between sprat and herring. Sprat lipid content was higher than herring, increasing with fish size and characterized by large proportions of monounsaturated fatty acids. Herring lipid content was related to the reproductive cycle and proportions of PUFAs were high compared with sprat. Levels of essential PUFAs were high in S. entomon compared with clupeids rendering it a valuable alternative prey species in the Baltic Sea ecosystem. The lipid dynamics of forage fish and benthos, combined with changes in availability and abundance, will affect growth and reproduction of their predators.

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