Diet of dominant demersal fish species in the Baltic Sea: Is flounder stealing benthic food from cod?

2020 ◽  
Vol 645 ◽  
pp. 159-170
Author(s):  
K Haase ◽  
A Orio ◽  
J Pawlak ◽  
M Pachur ◽  
M Casini
Keyword(s):  
Baltic Sea ◽  
Species Interactions ◽  
Feeding Habits ◽  
Demersal Fish ◽  
The Baltic Sea ◽  
Fish Prey ◽  
Feeding Mode ◽  
Offshore Area ◽  
The Baltic ◽  
Benthic Prey

Knowledge about ecological interactions between species is of paramount importance in ecology and ecosystem-based fisheries management. To understand species interactions, studies of feeding habits are required. In the Baltic Sea, there is good knowledge of the diet of cod, but little is known about the diet of flounder, the second most abundant demersal fish in the region. In this study, we investigated the diets of cod and flounder for the first time using stomach content data collected simultaneously in 2015-2017 over a large offshore area of the southern Baltic Sea. The diet of flounder was relatively constant between sizes and seasons and was dominated by benthos, with a high proportion in weight of the benthic isopod Saduria entomon. The diet of cod differed between seasons and showed an ontogenetic shift with a relative decrease of benthic prey and an increase of fish prey with size. Historic diet data of cod were used to explore cod diet changes over time, revealing a shift from a specialized to generalist feeding mode paralleled by a large relative decline in benthic prey, especially S. entomon. Flounder populations have increased in the past 2 decades in the study area, and therefore we hypothesized that flounder have deprived cod of important benthic resources through competition. This competition could be exacerbated by the low benthic prey productivity due to increased hypoxia, which could contribute to explaining the current poor status of the Eastern Baltic cod. The results of this study point to the importance of including flounder in multispecies end ecosystem models.

scholarly journals An ecosystem model of food web and fisheries interactions in the Baltic Sea

2003 ◽  
Vol 60 (5) ◽  
pp. 939-950 ◽  
Author(s):  
Chris J Harvey ◽  
Sean P Cox ◽  
Timothy E Essington ◽  
Sture Hansson ◽  
James F Kitchell
Keyword(s):  
Baltic Sea ◽  
Food Web ◽  
Species Interactions ◽  
Gadus Morhua ◽  
Population Analysis ◽  
Clupea Harengus ◽  
Trophic Relationships ◽  
The Baltic Sea ◽  
Management Actions ◽  
The Baltic

Abstract Because fisheries operate within a complex array of species interactions, scientists increasingly recommend multispecies approaches to fisheries management. We created a food web model for the Baltic Sea proper, using the Ecopath with Ecosim software, to evaluate interactions between fisheries and the food web from 1974 to 2000. The model was based largely on values generated by multispecies virtual population analysis (MSVPA). Ecosim outputs closely reproduced MSVPA biomass estimates and catch data for sprat (Sprattus sprattus), herring (Clupea harengus), and cod (Gadus morhua), but only after making adjustments to cod recruitment, to vulnerability to predation of specific species, and to foraging times. Among the necessary adjustments were divergent trophic relationships between cod and clupeids: cod exhibited top-down control on sprat biomass, but had little influence on herring. Fishing, the chief source of mortality for cod and herring, and cod reproduction, as driven by oceanographic conditions as well as unexplained variability, were also key structuring forces. The model generated many hypotheses about relationships between key biota in the Baltic Sea food web and may ultimately provide a basis for estimating community responses to management actions.

scholarly journals TRANSFER OF RADIOCAESIUM FROM CONTAMINATED BOTTOM SEDIMENTS TO MARINE ORGANISMS THROUGH BENTHIC FOOD CHAIN IN POST-FUKUSHIMA AND POST-CHERNOBYL PERIODS

2016 ◽  
Author(s):  
Roman Bezhenar ◽  
Kyung Tae Jung ◽  
Vladimir Maderich ◽  
Stefan Willemsen ◽  
Govert de With ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Bottom Sediments ◽  
Food Chain ◽  
Demersal Fish ◽  
Marine Organisms ◽  
Benthic Organisms ◽  
The Baltic Sea ◽  
Benthic Food ◽  
The Baltic ◽  
Deposit Feeding

Abstract. After the earthquake and tsunami on 11 March, 2011 damaged the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), an accidental release of a large amount of radioactive isotopes into both the air and the ocean occurred. Measurements provided by the Japanese agencies over the past four years show that elevated concentrations of 137Cs still remain in sediments, benthic organisms and demersal fishes in the coastal zone around the FDNPP. These observations indicate that there are 137Cs transfer pathways from bottom sediments to the marine organisms. To describe the transfer quantitatively, the dynamic food chain model BURN has been extended to include benthic marine organisms. The extended model takes into account both pelagic and benthic marine organisms grouped into several classes based on their trophic level and type of species: phytoplankton, zooplankton, and fishes (two types: piscivorous and non-piscivorous) for the pelagic food chain; deposit feeding invertebrates, demersal fishes feeding by benthic invertebrates and bottom omnivorous predators for the benthic food chain; crustaceans, molluscs and coastal predators feeding on both pelagic and benthic organisms. Bottom invertebrates ingest organic parts of bottom sediments with adsorbed radionuclides which then migrate up through the food chain. All organisms take radionuclides directly from water as well as food. The model was implemented into the compartment model POSEIDON-R and applied to the Northwestern Pacific for the period of 1945–2010 and then for the period of 2011–2020 to assess the radiological consequences of releases of 137Cs due to FDNPP accident. The model simulations for activity concentrations of 137Cs in both pelagic and benthic organisms in the coastal area around the FDNPP agree well with measurements for the period of 2011–2015. The decrease constant in the fitted exponential function of simulated concentration for the deposit ingesting invertebrates (0.45 y–1) is close to the decrease constant for the sediment observations (0.44 y–1), indicating that the gradual decrease of activity in the demersal fish (decrease constant is 0.46 y–1) was caused by the transfer of activity from organic matter deposited in bottom sediment through the deposit feeding invertebrates. The estimated from model transfer coefficient from bulk sediment to demersal fish in the model for 2012–2020 (0.13) is larger than that to the deposit feeding invertebrates (0.07) due to the biomagnification effect. In addition, the transfer of 137Cs through food webs for the period of 1945–2020 has been modelled for the Baltic Sea that was essentially contaminated due to global fallout and the Chernobyl accident. The model simulation results obtained with generic parameters are also in good agreement with available measurements in the Baltic Sea. Due to weak water exchange with the North Sea of the semi-enclosed Baltic Sea the chain of water-sediments- biota slowly evolves into a quasi-equilibrium state unlike the processes off the open Pacific Ocean coast where the FDNPP is located. Obtained results demonstrate the importance of the benthic food chain in the long-term transfer of 137Cs from contaminated bottom sediments to marine organisms and the potential of a generic model for the use in different regions of the World Ocean.

Comparison between spring and autumn infection by Corynosoma (Acanthocephala) in the ringed seal Pusa hispida in the Bothnian Bay of the Baltic Sea

Parasitology ◽  
1981 ◽  
Vol 82 (2) ◽  
pp. 287-296 ◽  
Author(s):  
Eero Helle ◽  
E. Tellervo Valtonen
Keyword(s):  
Baltic Sea ◽  
Feeding Habits ◽  
Ringed Seal ◽  
The Other ◽  
The Baltic Sea ◽  
Rate Of Development ◽  
Ringed Seals ◽  
Pusa Hispida ◽  
The Baltic ◽  
Bothnian Bay

SUMMARYCorynosoma spp. (Acanthocephala) infection in ringed seals (Pusa hispida) is compared in spring and in autumn in the Bothnian Bay, northern Baltic Sea. The material consists of more than 13400 specimens: 7590 from the intestines of 13 seals captured in April and May 1978 and 5850 from 29 seals captured in October and November.Corynosoma strumosum infection had approximately the same intensity in spring and autumn (mean 76 and 66 individuals/infected seal, maxmum 313 and 324 individuals, respectively). C. semerme specimens, on the other hand, were 37 times more numerous in spring than in autumn (504 compared with 136/infected seal, maximum 1700 and 1230 individuals, respectively). The ratio of C. strumosum to C. semerme was 1:6·3 in spring and 1:2·0 in autumn, as calculated from the total material. Corynosoma infection was more recent on average in spring than in autumn, as judged both from the proportion of males and immature females and from the distribution of C. semerme in the intestine. The feeding habits of the ringed seals and the rate of development of Corynosoma infection are discussed.

scholarly journals The Risk for Novel and Disappearing Environmental Conditions in the Baltic Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Thorsten Blenckner ◽  
Yosr Ammar ◽  
Bärbel Müller-Karulis ◽  
Susa Niiranen ◽  
Lars Arneborg ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Environmental Conditions ◽  
Species Interactions ◽  
Nutrient Management ◽  
Strong Support ◽  
The Baltic Sea ◽  
Management Scenarios ◽  
The Future ◽  
The Baltic ◽  
Environmental Novelty

Future climate biogeochemical projections indicate large changes in the ocean with environmental conditions not experienced at present referred to as novel, or may even disappear. These climate-induced changes will most likely affect species distribution via changes in growth, behavior, evolution, dispersal, and species interactions. However, the future risk of novel and disappearing environmental conditions in the ocean is poorly understood, in particular for compound effects of climate and nutrient management changes. We map the compound risk of the occurrence of future novel and disappearing environmental conditions, analyze the outcome of climate and nutrient management scenarios for the world’s largest estuary, the Baltic Sea, and the potential consequences for three charismatic species. Overall, the future projections show, as expected, an increase in environmental novelty over time. The future nutrient reduction management that improves the eutrophication status of the Baltic Sea contributes to large novel and disappearing conditions. We show the consequences of novel and disappearing environmental conditions for fundamental niches of three charismatic species under different scenarios. This first step toward comprehensively analyzing environmental novelty and disappearing conditions for a marine system illustrates the urgent need to include novelty and disappearing projection outputs in Earth System Models. Our results further illustrate that adaptive management is needed to account for the emergence of novelty related to the interplay of multiple drivers. Overall, our analysis provides strong support for the expectation of novel ecological communities in marine systems, which may affect ecosystem services, and needs to be accounted for in sustainable future management plans of our oceans.

Modelling indices of abundance and size-based indicators of cod and flounder stocks in the Baltic Sea using newly standardized trawl survey data

2017 ◽  
Vol 74 (5) ◽  
pp. 1322-1333 ◽  
Author(s):  
Alessandro Orio ◽  
Ann-Britt Florin ◽  
Ulf Bergström ◽  
Ivo Šics ◽  
Tatjana Baranova ◽  
...  
Keyword(s):  
Time Series ◽  
Baltic Sea ◽  
Stock Assessment ◽  
Generalized Additive Models ◽  
Sustainable Use ◽  
Demersal Fish ◽  
Additive Models ◽  
Trawl Survey ◽  
The Baltic Sea ◽  
The Baltic

Standardized indices of abundance and size-based indicators are of extreme importance for monitoring fish population status. The main objectives of the current study were to (i) combine and standardize recently performed trawl survey with historical ones, (ii) explore and discuss the trends in abundance, and (iii) the trends in maximum length (Lmax) for cod (Gadus morhua) and flounder (Platichthys flesus) stocks in the Baltic Sea. Standardization of catch per unit of effort (CPUE) from trawl surveys from 1978 to 2014 to swept area per unit of time was conducted using information on trawling speed and horizontal opening of the trawls. CPUE data for cod and flounder stocks were modelled using generalized additive models (GAMs) in a delta modelling approach framework, while the Lmax data were modelled using ordinary GAMs. The CPUE time series of the Eastern Baltic cod stock closely resembles the spawning stock biomass trend from analytical stock assessment. The results obtained furnish evidence of the cod spill-over from Subdivisions (SD) 25–28 to SD 24. The decline of Lmax in recent years was evident for both species in all the stocks analysed indicating that the demersal fish community is becoming progressively dominated by small individuals. It is concluded that the standardization of long time series of fisheries-independent data constitutes a powerful tool that could help improve our knowledge on the dynamics of fished populations, thus promoting a long-term sustainable use of these marine resources.

scholarly journals Transfer of radiocaesium from contaminated bottom sediments to marine organisms through benthic food chains in post-Fukushima and post-Chernobyl periods

2016 ◽  
Vol 13 (10) ◽  
pp. 3021-3034 ◽  
Author(s):  
Roman Bezhenar ◽  
Kyung Tae Jung ◽  
Vladimir Maderich ◽  
Stefan Willemsen ◽  
Govert de With ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Bottom Sediments ◽  
Food Chain ◽  
Demersal Fish ◽  
Marine Organisms ◽  
Benthic Organisms ◽  
The Baltic Sea ◽  
Benthic Food ◽  
The Baltic ◽  
Deposit Feeding

Abstract. After the earthquake and tsunami on 11 March 2011 damaged the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), an accidental release of a large amount of radioactive isotopes into both the air and the ocean occurred. Measurements provided by the Japanese agencies over the past 5 years show that elevated concentrations of 137Cs still remain in sediments, benthic organisms, and demersal fishes in the coastal zone around the FDNPP. These observations indicate that there are 137Cs transfer pathways from bottom sediments to the marine organisms. To describe the transfer quantitatively, the dynamic food chain biological uptake model of radionuclides (BURN) has been extended to include benthic marine organisms. The extended model takes into account both pelagic and benthic marine organisms grouped into several classes based on their trophic level and type of species: phytoplankton, zooplankton, and fishes (two types: piscivorous and non-piscivorous) for the pelagic food chain; deposit-feeding invertebrates, demersal fishes fed by benthic invertebrates, and bottom omnivorous predators for the benthic food chain; crustaceans, mollusks, and coastal predators feeding on both pelagic and benthic organisms. Bottom invertebrates ingest organic parts of bottom sediments with adsorbed radionuclides which then migrate up through the food chain. All organisms take radionuclides directly from water as well as food. The model was implemented into the compartment model POSEIDON-R and applied to the north-western Pacific for the period of 1945–2010, and then for the period of 2011–2020 to assess the radiological consequences of 137Cs released due to the FDNPP accident. The model simulations for activity concentrations of 137Cs in both pelagic and benthic organisms in the coastal area around the FDNPP agree well with measurements for the period of 2011–2015. The decrease constant in the fitted exponential function of simulated concentration for the deposit-feeding invertebrates (0.45 yr−1) is close to the observed decrease constant in sediments (0.44 yr−1). These results strongly indicate that the gradual decrease of activity in demersal fish (decrease constant is 0.46 yr−1) is caused by the transfer of activity from organic matter deposited in bottom sediment through the deposit-feeding invertebrates. The estimated model transfer coefficient from bulk sediment to demersal fish in the model for 2012–2020 (0.13) is larger than that to the deposit-feeding invertebrates (0.07). In addition, the transfer of 137Cs through food webs for the period of 1945–2020 has been modelled for the Baltic Sea contaminated due to global fallout and from the Chernobyl accident. The model simulation results obtained with generic parameters are also in good agreement with available measurements in the Baltic Sea. Unlike the open coastal system where the FDNPP is located, the dynamics of radionuclide transfer in the Baltic Sea reach a quasi-steady state due to the slow rate in water mass exchange in this semi-enclosed basin. Obtained results indicate a substantial contribution of the benthic food chain in the long-term transfer of 137Cs from contaminated bottom sediments to marine organisms and the potential application of a generic model in different regions of the world's oceans.

scholarly journals Past and Current Trends of Coastal Predatory Fish in the Baltic Sea with a Focus on Perch, Pike, and Pikeperch

Fishes ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 7 ◽  
Author(s):  
Jens Olsson
Keyword(s):  
Baltic Sea ◽  
Species Interactions ◽  
Current Data ◽  
Predatory Fish ◽  
The Baltic Sea ◽  
Current Trends ◽  
Impacting Factors ◽  
Past Data ◽  
The Baltic ◽  
And Function

Coastal predatory fish are of key importance for the provisioning of ecosystem services in the Baltic Sea. Worldwide, however, there has been a general and sharp decline in predatory fish populations, in turn threatening the viability and function of marine ecosystems. On the basis of the literature, the past (data until the 2000s) and current (data until early and mid 2010s) trends in abundance of coastal predatory fish in the Baltic Sea are reviewed in this paper. Potentially important impacting factors behind the temporal development of the populations and measures to strengthen and restore them are also discussed. Available data from coastal fish monitoring programs suggest a stable or increasing abundance of coastal predatory fish as a functional group and for the species perch in the majority of areas assessed in the Baltic Sea. For pike and pikeperch, data to support assessments is scarce, but suggest substantial declines in the abundance of both species in most assessed areas. The impacting factors behind these patterns vary between species and areas, but include climate, habitat exploitation, fishing, and species-interactions in the coastal food web. Measures to restore and support coastal predatory fish communities should follow an ecosystem-based approach to management and include efforts to regulate fisheries sectors in combination with habitat protection and restoration.

Temporal and spatial sedimentation rate variabilities in the eastern Gotland Basin, the Baltic Sea

Boreas ◽  
2002 ◽  
Vol 31 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Christian Christiansen ◽  
Helmar Kunzendorf ◽  
Kay-Christian Emeis ◽  
Rudolf Endler ◽  
Ulrich Struck ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Sedimentation Rate ◽  
The Baltic Sea ◽  
Gotland Basin ◽  
Temporal And Spatial ◽  
The Baltic

Russian Oil: Production and Exports

2003 ◽  
pp. 136-146
Author(s):  
K. Liuhto
Keyword(s):  
Baltic Sea ◽  
Statistical Data ◽  
Oil Production ◽  
The Baltic Sea ◽  
North West ◽  
The North ◽  
Oil Transportation ◽  
Sea Ports ◽  
The Baltic

Statistical data on reserves, production and exports of Russian oil are provided in the article. The author pays special attention to the expansion of opportunities of sea oil transportation by construction of new oil terminals in the North-West of the country and first of all the largest terminal in Murmansk. In his opinion, one of the main problems in this sphere is prevention of ecological accidents in the process of oil transportation through the Baltic sea ports.

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