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| 2. |
- Rosenberg, Rutger, et al.
(författare)
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Marine environment quality assessment of the Skagerrak - Kattegat
- 1996
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Ingår i: Journal of Sea Research. - 1385-1101 .- 1873-1414. ; 35:1-3, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- This quality assessment of the Skagerrak-Kattegat is mainly based on recent results obtained within the framework of the Swedish multidisciplinary research projekt ‘Large-scale environmental effects and ecological processes in the Skagerrak-Kattegat’ completed with relevant data from other research publications. The results show that the North Sea has a significant impact on the marine ecosystem in the Skagerrak and the northern Kattegat. Among environmental changes recently documented for some of these areas are: increased nutrient concentrations, increased occurrence of fast-growing filamentous algae in coastal areas affecting nursery and feeding conditions for fish, declining bottom water oxygen concentrations with negative effects on benthic fauna, and sediment toxicity to invertebrates also causing physiological responses in fish. It is concluded that, due to eutrophication and toxic substances, large-scale environmental changes and effects occur in the Skagerrak-Kattegat area.
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| 3. |
- Almroth Rosell, Elin, 1977, et al.
(författare)
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Effects of simulated natural and massive resuspension on benthic oxygen, nutrient and dissolved inorganic carbon fluxes in Loch Creran, Scotland
- 2012
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Ingår i: Journal of Sea Research. - : Elsevier BV. - 1385-1101. ; 72, s. 38-48
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Tidskriftsartikel (refereegranskat)abstract
- The effect of repeated natural resuspension on benthic oxygen consumption and the effect of natural and massive resuspension on oxygen consumption and fluxes of phosphate, silicate, ammonium and dissolved inorganic carbon (DIC) were studied at two stations (S1 and S2) in a Scottish sea loch. Station S11 had organically enriched sediment and station S1 had lower organic content in the sediment. The fluxes were measured in situ using the Göteborg benthic lander. Natural resuspension, simulating resuspension events due to strong wind, waves or currents, and massive resuspension, simulating resuspension due to e.g. trawling or dredging, were created inside the incubation chambers by regulating the stirring of the incubated overlying water or by retracting and shaking the incubated sediment. Natural resuspension showed clear effects on the oxygen consumption at station S11, where it increased with an average of 12.8 (standard error (s.e.) 0.17) and 7.7 (s.e. 0.12) mmol m− 2 d− 1 during the first and second incubations, respectively. At station S1 there was no clear effect of natural resuspension on the oxygen consumption. Massive resuspension increased the oxygen consumption on S1 with an average of 608 (standard deviation (sd) 366) mmol m− 2 d− 1 and on S11 with an average of 2396 (sd 2265) mmol m− 2 d− 1. The fluxes of ammonium, phosphate and silicate were affected by the massive resuspension in 50, 14 and 33% of the chambers, respectively, on station S11. However, in the majority of the cases there were no effects on the nutrient and DIC fluxes of massive resuspension. The absolute concentrations of DIC, ammonium and silicate did however instantly increase with an average of 419 (sd 297), 48 (sd 27) and 6.9 (sd 3.7) μM, respectively, at S11 upon massive resuspension. The concentrations of phosphate decreased instantly with an average of 0.2 (sd 0.1) μM. On station S1 there were effects only on the ammonium and silicate concentrations, which increased with 0.8 (sd 0.3) and 1.13 (sd 0.36) μM, respectively. The large increase in oxygen consumption due to massive resuspension indicates that activities like e.g. trawling and dredging that take place in areas where water exchange occurs infrequently may lead to oxygen depletion in bottom water, which in turn might affect the ecological balance. Silicate, ammonium and DIC can be released due to massive resuspension and contribute to increased algal blooms in surface waters.
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| 4. |
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| 5. |
- Bergström, Ulf, et al.
(författare)
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Diet overlap between juvenile flatfish and the invasive round goby in the central Baltic Sea
- 2016
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Ingår i: Journal of Sea Research. - : Elsevier BV. - 1385-1101 .- 1873-1414. ; 107, s. 121-129
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Annan publikation (refereegranskat)abstract
- The present study offers a comprehensive analysis of changes in the abundance and diet composition of juvenile flounder (Platichthys flesus) and turbot (Psetta maxima), along with other dominant coastal fish species, before and after the establishment of the alien round goby off an exposed stretch of coast in the eastern Baltic Sea.In the study area, the round goby (Neogobius melanostomus) was recorded for the first time in 2009. After a few years of low abundance, a sharp increase in the population occurred. After the round goby invasion, flatfish juveniles exhibited an increased diet overlap with other species and had a lower feeding success, reflecting an increase in resource competition. For juvenile turbot, the increase was mainly caused by the round goby, while for flounder it was due to both the round goby and the lesser sandeel (Ammodytes tobianus).Juvenile turbot, whose dominant food item before the round goby establishment had been mysids, shifted their diet towards Crangon crangon, reflecting a decrease in mysid abundance by three orders of magnitude and a concurrent doubling in C. crangon abundance in the habitat. At the same time a significant decrease in turbot recruitment was observed.Juvenile flounder had the widest food spectrum of the studied species. When the availability of the primary food item, Bathyporeia pilosa, decreased, flounder juveniles adapted by increasing the share of zooplankton in their diets. No changes in flounder feeding success and recruitment were observed. However, the recruitment estimates of flounder and turbot show an increasing co-variation after the round goby invasion, suggesting that recruitment of the species may currently be regulated by processes in the common nursery habitat. (C) 2015 Elsevier B.V. All rights reserved.
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| 6. |
- Bernard, Guillaume, et al.
(författare)
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Quantifying bioturbation across coastal seascapes : Habitat characteristics modify effects of macrofaunal communities
- 2019
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Ingår i: Journal of Sea Research. - : Elsevier BV. - 1385-1101 .- 1873-1414. ; 152
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Tidskriftsartikel (refereegranskat)abstract
- Bioturbation by benthic macrofauna communities plays a significant role in the setting and maintenance of important ecosystem functions and the delivery of associated ecosystem services. We investigated the context dependence of bioturbation performed by natural benthic communities in the coastal northern Baltic Sea by quantifying three bioturbation metrics (particle mixing intensity, surface sediment reworking and bioturbation depth) across 18 sites ranging from cohesive muddy sediments to non-cohesive coarse sands, while accounting for the complexity of natural communities and habitat characteristics. We identified two distinct patterns of bioturbation; in fine sediments bioturbation rates were highly variable and in coarse sediments bioturbation rates were less variable and characterized by lower maximal values. Using distance-based linear multiple regressions, we found that 75.5% of the variance in bioturbation rates in fine sediment could be explained by key functional groups/species abundance and/or biomass (i.e. biomass of the gallery-diffusors and abundances of biodiffusors, surface modifiers, conveyors and gallery diffusors, respectively). In coarse sediment, 47.8% of the variance in bioturbation rates could be explained by a combination of environmental factors (grain size, organic matter content, buried plant material) and faunal functional groups, although fauna alone explained only 13% of this variance. Bioturbation in fine sediments was therefore more predictable based on the composition of benthic fauna. In coarse sediment, the bioturbation activities of benthic fauna were strongly modified by habitat characteristics (including the presence of buried plant material, sediment organic content and grain size) whereas in fine sediments this was not the case. Our results therefore highlight that variability in spatial patterns of bioturbation is a result of complex relationships between macrofauna community structure, sediment type and other habitat characteristics, likely modifying bioturbation performance of individual fauna.
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| 7. |
- Caradec, S., et al.
(författare)
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Macrofaunal reworking activities and hydrocarbon redistribution in an experimental sediment system
- 2004
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Ingår i: Journal of Sea Research. - : Elsevier BV. - 1385-1101. ; 52:3, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- The influence of macrofaunal reworking activities on the redistribution of particle associated hydrocarbon compounds (HC) was experimentally investigated. Two distinct hydrocarbon mixtures adsorbed on montmorillonite particles (< 4 gm diameter) were added to the surface and deeper (2.5 cm) sediment layers. For comparison, luminophores (100-160 mum diameter) were added in the two deposit layers. At the start of the experiment, four macrobenthic species (the bivalve Abra nitida, the polychaete Scalibregma inflatum, and the echmoderms Amphiura filiformis and Echinocardium cordatum) were added to the sediment surface. The macrofauna added rapidly transferred HC from the surface sediment down to similar to5 cm depth by both continuous (biodiffusion) and non-continuous (biotransport) transport. Hydrocarbon compounds initially added to the deeper sediment layer were only subject to biodiffusion-like transport. Apparent biodiffusion coefficients (Db) quantified by using a 1-D model were between 0.5 and 8.4 x 10(-3) cm(2) d(-1), and biotransport coefficients (r) ranged from 2.0 to 27.6 X 10(-3) d(-1). Thus, the four species studied did not have the same effect on particle redistribution and, consequently, on HC repartition in the sediments. E. cordatum was the most efficient reworker. The present study demonstrated the importance of particle size selectivity by benthic fauna, and verified that macrofaunal reworking activities may redeposit sediment from deeper sediment layers on the sediment surface. Both processes have obvious implications for rates and pathways during organic matter mineralisation in marine sediments. (C) 2004 Elsevier B.V. All rights reserved.
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| 8. |
- Cardinale, Massimiliano, et al.
(författare)
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Variability and connectivity of plaice populations from the Eastern North Sea to the Western Baltic Sea, and implications for assessment and management
- 2013
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Ingår i: Journal of Sea Research. - : Elsevier BV. - 1385-1101 .- 1873-1414. ; 84, s. 40-48
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Tidskriftsartikel (refereegranskat)abstract
- An essential prerequisite of sustainable fisheries is the match between biologically relevant processes and management action. Various populations may however co-occur on fishing grounds, although they might not belong to the same stock, leading to poor performance of stock assessment and management. Plaice in Kattegat and Skagerrak have traditionally been considered as one stock unit. Current understanding indicates that several plaice components may exist in the transition area between the North Sea and the Baltic Sea. A comprehensive review of all available biological knowledge on plaice in this area is performed, including published and unpublished literature together with the analyses of commercial and survey data and historical tagging data. The results suggest that plaice in Skagerrak is closely associated with plaice in the North Sea, although local populations are present in the area Plaice in Kattegat, the Belts Sea and the Sound can be considered a stock unit, as is plaice in the Baltic Sea. The analyses revealed great heterogeneity in the dynamics and productivity of the various local components, and suggested for specific action to maintain biodiversity. (C) 2013 Elsevier B.V. All rights reserved.
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| 9. |
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| 10. |
- Cossellu, Michele, 1980, et al.
(författare)
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Recent environmental changes and filamentous algal mats in shallow bays on the Swedish West Coast – a result of climate change?
- 2010
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Ingår i: Journal of Sea Research. - : Elsevier BV. - 1385-1101. ; 63:3-4, s. 203-212
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Tidskriftsartikel (refereegranskat)abstract
- Over the last thirty years, many shallow estuarine bays, located in Scandinavian sheltered coastal environments, have been subject to the increased dominance of opportunistic species of filamentous green algae, oxygen deficiency in bottom waters and the alteration of flora and fauna. Human-induced eutrophication has been held responsible for these recent changes, but from this study the importance of climatic factors emerges. This research is based on the analysis of sediment cores from 8 shallow areas (d < 50 cm) along the Bohuslän archipelago, Swedish west coast, and focuses on their recent (< 100 years) sedimentary evolution. Evidence of hydrodynamic change was observed in the sediments, where modern fining-upward sequences contrast with the expected coarsening upward model due to ongoing land uplift. Heavy metal concentrations from modern pollution and 14C dating of mollusk shells and eelgrass roots provided the age control, and allowed to place these changes within the last three decades. Data were compared with historical meteorological records (seasonal warming, modification of dominant winds and upwelling and reduction of sea-ice), and a clear connection emerged between the environmental changes and variations in the North Atlantic Ocean weather pattern. The increase of winter temperature and reduction of reworking winter sea-ice in these sheltered bays increased the storing of nutrients in the sediments and the turnover of organic matter, favoring the early growth stage of opportunistic algae in the most sheltered areas of the archipelago. This, together with human-induced modifications (overfishing and eutrophication), increased the possibility of opportunistic explosions, which in turn determined a reduced water exchange, the increased deposition of fine sediments and organic matter and evolving hypoxic conditions.
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