| 1. |
- Granéli, Edna
(författare)
-
Nutrient limitation of phytoplankton biomass in a brackish water bay highly influenced by river discharge
- 1987
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 25:5, s. 555-565
-
Tidskriftsartikel (refereegranskat)abstract
- Laboratory nutrient enrichment experiments (n=30) with the indigenous phytoplankton community from the brackish (mean salinity 16‰) Laholm Bay, south-east Kattegat, were performed during the period August 1981 to August 1983. The results show that nitrogen is the most limiting nutrient for potential phytoplankton biomass formation, despite a high input of inorganic nitrogen to the bay from rivers draining heavily fertilized agricultural areas. Phosphorus, silica, trace metal or chelator (EDTA) additions to Laholm Bay phytoplankton had no significant effect on biomass yield.
|
|
| 2. |
- Humborg, Christoph, et al.
(författare)
-
Nutrient land-sea fluxes in oligothrophic and pristine estuaries of the Gulf of Bothnia, Baltic Sea
- 2003
-
Ingår i: Estuarine, Coastal and Shelf Science. - 0272-7714 .- 1096-0015. ; 56:3-4, s. 781-793
-
Tidskriftsartikel (refereegranskat)abstract
- Estuaries are often seen as important filters between land and the sea for inorganic and organic nutrients. This paper aims at estimating the estuarine fluxes of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and dissolved silicate for the major oligothrophic and pristine rivers running into the Bothnian Bay (BB) and the Bothnian Sea (BS), the northern subarctic subbasins of the Baltic Sea. Long-term data sets for these rivers and their estuaries as well as for the BB and BS were analyzed to assess whether these estuaries are sinks for inorganic nutrients. Most studied estuaries can be characterized as salt wedge estuaries with little exchange between the fresh seaward-flowing river water and the inward-flowing seawater. Estimates of water transit times ranged between 1 and 14 days. In most estuaries of the BB, N-depleted river water meets P-depleted seawater during the growth period. These findings were corroborated by mixing diagrams showing that the inner areas of the estuaries were N-depleted in summer. In the BS, on the other hand, both rivers and seawater were mostly N-depleted during summer. Thus, for most estuaries of this region of the Baltic Sea, primary productivity is presumably lower than or equal to that of offshore. The low productivity is also reflected in the sediments. The coastal sediments did not differ from the offshore stations in accumulation rates as well as the content of organic matter and nutrients, indicating that estuarine nutrient burial is not always higher as normally observed in other temperate systems. Finally, the estuaries of the pristine rivers in the northernmost part of the BB import DIN during summer, whereas the estuaries of the rivers in the BS import DIP during winter, from the sea. ⌐ 2003 Elsevier Science B.V. All rights reserved.
|
|
| 3. |
- Adler, Sven
(författare)
-
Modelling and predicting habitats for the neobiotic American razor clam Ensis leei in the Wadden Sea
- 2019
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 231
-
Tidskriftsartikel (refereegranskat)abstract
- Neobiotic species can have profound impacts on food webs and entire ecosystems. The American razor clam Ensis leei was introduced into the Wadden Sea by vessels in the late 1970s and has since spread widely. It has been suggested that Ensis does not interact strongly with other benthic species. The abundance and biomass of E. leei were recorded in 2393 samples in the north-eastern Wadden Sea and 800 samples in the south-eastern Wadden Sea over a total period of 9 years. Using an interdisciplinary approach, we developed a habitat prediction model using sedimentological and hydrodynamic predictors to help understand the shape of the ecological niche occupied by Ensis in the Wadden Sea. Our model showed that Ensis preferred areas with moderately high bed shear stress and prolonged or constant water coverage. Ensis preferred coarse sediments in the northern sub-area but coarse and muddy sediments in the southern sub-area and was negatively affected by the sand mason worm Lanice conchilega in the northern sub-area. Predictions of the spatial distribution of Ensis using the northern and southern datasets revealed major differences in predicted hot-spots throughout the entire study site. This study thus highlights the need to collect a sufficiently large dataset from different sub-areas of the Wadden Sea to allow valid conclusions to be drawn regarding the spatial distribution of Ensis. The negative effects of L. conchilega on Ensis abundance and biomass as well as the occurrence of Ensis in muddy sediments in the south suggest that the ecological niche of this neobiotic species is likely to overlap partly with the native fauna of the Wadden Sea.
|
|
| 4. |
- Adler, Sven
(författare)
-
Modelling distribution of common scoter (Melanitta nigra) by its predominant prey, the American razor clam (Ensis leei) and hydrodynamic parameters
- 2019
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 225
-
Tidskriftsartikel (refereegranskat)abstract
- The non-breeding distribution of common scoter (Melanitta nigra), which occur in high densities offshore from the eastern Wadden Sea, has been well documented in recent decades, but factors influencing these patterns remain poorly known. We investigated the prey choice of 88 common scoter using stomach contents of beached birds collected over a period of 12 years. We then used benthos data and hydrodynamic parameters to model the June-September distribution patterns during the flightless period of common scoter based on transect count data off the north-eastern German Wadden Sea.Benthic fauna biomass in areas used by common scoter was higher than in areas where the species was absent. American razor clam (Ensis leei) invaded the Wadden Sea during the end of the 1970s and was the most common prey, both in benthos samples from below feeding common scoter and in stomach samples. The relatively high flesh to shell ratio of the American razor clam makes it the most attractive available prey item for common scoter.The abundance of American razor clams explained the distribution of scoter to a high degree, although the best model fit included negative effects of water depth and positive effects of bed shear stress intensity on scoter abundance. Our data show that the neobiotic American razor clams have become an important part of the diet of these sea ducks, whereas the cut trough shell (Spisula subtruncata) was of substantially lesser importance than expected from historical data. Our study shows the ability of a top avian predator to respond to novel developments in bivalve prey availability over periods of a few decades.
|
|
| 5. |
- Amir, Omar A., et al.
(författare)
-
Feeding ecology of the Indo-Pacific bottlenose dolphin (Tursiops aduncus) incidentally caught in the gillnet fisheriesoff Zanzibar, Tanzania
- 2005
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 63:3, s. 429-437
-
Tidskriftsartikel (refereegranskat)abstract
- The stomach contents of 26 Indo-Pacific bottlenose dolphins (Tursiops aduncus) incidentally caught in gillnet fisheries aroundUnguja Island (Zanzibar) between February 2000 and August 2002 were examined. The relative importance of each prey species wasassessed through indices of relative importance. In total, 1403 prey items comprising 50 species of bony fish and three species ofsquid were identified from food remains. Five species of fish, Uroconger lepturus, Synaphobranchus kaupii, Apogon apogonides,Lethrinus crocineus, Lutjanus fulvus, and three species of squid, Sepioteuthis lessoniana, Sepia latimanus and Loligo duvauceli, werethe most important prey species. Based on an index that included frequency of occurrence, percentage by number and by weight,Uroconger lepturus proved to be the most important prey species of mature dolphins whereas Apogon apogonides was the preferredprey of immature dolphins. These results indicate that Indo-Pacific bottlenose dolphins off the coast of Zanzibar forage ona relatively large number of prey species, but that only a few small- and medium-sized neritic fish and cephalopods contributesubstantially to the diet. Further, the ecology and behavior of the preferred fish prey species indicate that the dolphins forage overreef or soft bottom substrata and near the shore.
|
|
| 6. |
- Andersson, Agneta, et al.
(författare)
-
Influence of allochthonous dissolved organic matter on pelagic basal production in a northerly estuary
- 2018
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier. - 0272-7714 .- 1096-0015. ; 204, s. 225-235
-
Tidskriftsartikel (refereegranskat)abstract
- Phytoplankton and heterotrophic bacteria are key groups at the base of aquatic food webs. In estuaries receiving riverine water with a high content of coloured allochthonous dissolved organic matter (ADOM), phytoplankton primary production may be reduced, while bacterial production is favoured. We tested this hypothesis by performing a field study in a northerly estuary receiving nutrient-poor, ADOM-rich riverine water, and analyzing results using multivariate statistics. Throughout the productive season, and especially during the spring river flush, the production and growth rate of heterotrophic bacteria were stimulated by the riverine inflow of dissolved organic carbon (DOC). In contrast, primary production and photosynthetic efficiency (i.e. phytoplankton growth rate) were negatively affected by DOC. Primary production related positively to phosphorus, which is the limiting nutrient in the area. In the upper estuary where DOC concentrations were the highest, the heterotrophic bacterial production constituted almost 100% of the basal production (sum of primary and bacterial production) during spring, while during summer the primary and bacterial production were approximately equal. Our study shows that riverine DOC had a strong negative influence on coastal phytoplankton production, likely due to light attenuation. On the other hand DOC showed a positive influence on bacterial production since it represents a supplementary food source. Thus, in boreal regions where climate change will cause increased river inflow to coastal waters, the balance between phytoplankton and bacterial production is likely to be changed, favouring bacteria. The pelagic food web structure and overall productivity will in turn be altered. (C) 2018 The Authors. Published by Elsevier Ltd.
|
|
| 7. |
- Andersson, Agneta, et al.
(författare)
-
Key role of phosphorus and nitrogen in regulating cyanobacterial community composition in the northern Baltic Sea
- 2015
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 164, s. 161-171
-
Tidskriftsartikel (refereegranskat)abstract
- Despite cyanobacteria being a key phytoplankton group in the Baltic Sea, the factors governing their community structure are still poorly understood. Here, we studied the occurrence of the orders Chroococcales, Oscillatoriales and Nostocales, and potentially explanatory variables at five locations in the northern Baltic Sea from June September, 1998-2012. Cyanobacteria constituted 1-36% of the total phytoplankton biomass along the north south gradient. In the Bothnian Bay, Chroococcales and Oscillatoriales dominated the cyanobacterial community, whereas in the Bothnian Sea and northern Baltic Proper, Nostocales was the dominant group. The dominance of Chroococcales was coupled to low salinity and low total phosphorus, whereas Oscillatoriales correlated with high total nitrogen and low salinity. Nostocales correlated to high total phosphorus, inorganic phosphorus and salinity. Chroococcales showed an increase over time in the offshore Bothnian Bay, whereas Nostocales increased in the coastal Bothnian Sea and coastal Baltic Proper. The increase of Nostocales in the coastal Bothnian Sea was explained by a rise in total phosphorus and decrease in dissolved inorganic nitrogen compared to an increase of total nitrogen and phosphorus in the coastal Baltic Proper. No significant trends were observed in the cyanobacterial community in the offshore Bothnian Sea and the offshore northern Baltic Proper. We concluded that Chroococcales may be a useful indicator for increased phosphorus levels in waters with low phosphorus concentrations, whereas Nostocales could be used as a quality indicator for increasing phosphorus concentrations in waters with low inorganic N/P ratios (< 20), such as in the coastal Bothnian Sea and Baltic Proper.
|
|
| 8. |
|
|
| 9. |
- Andrén, Elinor
(författare)
-
Changes in the composition of the diatom flora during the last century indicate increased eutrophication of the oder estuary, south-western Baltic Sea
- 1999
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Academic Press. - 0272-7714 .- 1096-0015. ; 48, s. 665-676
-
Tidskriftsartikel (refereegranskat)abstract
- Four short sediment cores from the Oder estuary, south-western Baltic Sea, were studied with respect to their siliceous microfossil and organic carbon content. The sediments were dated by Pb-210. The objective was to detect and date changes in the composition of the diatom flora and link these changes to increased human impact in the drainage area during recent centuries. Two of the cores showed an unperturbed sedimentary sequence representing a complete historical record. A change in the composition of the diatom assemblages attributable to anthropogenic factors was recorded. This was dated to about 1900 in the Oderhaff. The change consisted of an increase in species that thrive in eutrophic waters and those indicating increased salinity or the availability of inorganic nutrients.
|
|
| 10. |
- Andrén, Elinor, et al.
(författare)
-
Reconstructing the history of eutrophication and quantifying total nitrogen reference conditions in Bothnian Sea coastal waters
- 2017
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Academic Press. - 0272-7714 .- 1096-0015. ; 198, s. 320-328
-
Tidskriftsartikel (refereegranskat)abstract
- Reference total nitrogen (TN) concentrations for the Gårdsfjärden estuary in the central Bothnian Sea, which receives discharge from an industrial point-source, have been estimated from diatom assemblages using a transfer function. Sedimentological and diatom evidence imply a good ecological status before 1920 with an assemblage dominated by benthic taxa indicating excellent water transparency, high diatom species richness and less organic sedimentation resulting in homogeneous well oxygenated sediments. A change in the diatom assemblage starts between 1920 and 1935 when the species richness declines and the proportion of planktic taxa increases. Increased organic carbon sedimentation after 1920 led to hypoxic bottom waters, and the preservation of laminae in the sediments. The trend in the reconstructed TN-values agrees with the history of the discharge from the mill, reaching maximum impact during the high discharge between 1945 and 1990. The background condition for TN in Gårdsfjärden is 260-300 μg L-1, reconstructed until 1920.
|
|
| 11. |
- Angeler, David
(författare)
-
Nutrient fluxes in a semi-arid microtidal mangrove wetland in the Gulf of California
- 2009
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 82, s. 654-662
-
Tidskriftsartikel (refereegranskat)abstract
- Nutrient (C, N and P) fluxes were monitored in a microtidal semi-arid mangrove system, which links a semi-enclosed shallow coastal lagoon with the Gulf of California. We assessed the role of the mangrove ecosystem as a nutrient sink/source and determined how mangrove litterfall rates, tidal regime and climate factors influence these fluxes. Despite high seasonal differences in DOC, POC, N-NO(3)(-) and TP levels, nutrient concentrations were only marginally influenced by either hydrological variables or the concentration of these fractions in the adjacent lagoon. The carbon budget appeared to be balanced throughout the study. Retention rates in the mangrove system were related to litterfall rates. Export of DIN was observed mainly in the wet season due to the low nitrogen assimilation efficiency of the system. Import of organic nitrogen was related to the high retention efficiency of particulate organic nitrogen. Phosphorus fractions were imported and retained in the mangrove supporting previous findings that mangroves are phosphorus sinks. Finally, through a simple meta-analysis we tested the quantitative importance of main variables (tidal flow, tidal elevation, tidal range, rainfall, mangrove catchment area, litterfall) controlling mangrove nutrient dynamics. Although results suggest that generalizations can be made about factors regulating nutrient export from mangroves, the lack of statistical significance highlights the relative importance of the local environment for the magnitude of nutrient exchange in mangroves. Future research should focus on finding mechanistic models to explain these general patterns, taking into account the main biogeochemical processes and their roles in coastal ecosystem ecology. (C) 2009 Elsevier Ltd. All rights reserved.
|
|
| 12. |
- Bell, Olivia, et al.
(författare)
-
The effects of eutrophication and browning on prey availability and body growth of the three-spined stickleback (Gasterosteus aculeatus)
- 2022
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 267
-
Tidskriftsartikel (refereegranskat)abstract
- Shallow coastal areas often have high productivity and diversity, in part due to the high availability of light and nutrients. At the same time, they are exposed to multiple environmental pressures, such as browning and eutrophication. Browning is mainly caused by runoff bringing coloured dissolved organic matter (CDOM), reducing light availability in waters, whereas eutrophication is caused by high nutrient loading, leading to eutrophication symptoms such as algal blooms. Existing variation and further change in light and nutrients of coastal areas could have large implications for aquatic food webs, including fish. For instance, reduced light might alter food availability and reduce foraging abilities, whereas increased nutrient supply might, depending on the extent, increase food availability. In this study, we performed a mesocosm experiment, including benthic and pelagic communities, together with young-of-the-year three-spined stickleback (Gasterosteus aculeatus) as predators. The three-spined stickleback is not only a common model organism but also an increasingly common and important mesopredator in the Baltic Sea. We examined the extent to which browning and nutrient enrichment, alone and in combination, influenced the density, biomass, and composition of stickleback prey, and diet choice, body growth and condition of the stickleback. Stickleback body growth was positively affected by nutrient-enrichment, probably because of a positive bottom-up effect with increased primary production, as evident in the much higher chlorophyll -a concentrations in the pelagic habitat, and increased food availability. In contrast, there was a marginal negative effect of browning on stickleback body growth and condition, most likely due to negative effects of reduced visibility on feeding rates. We also found that prey availability increased with nutrient-enrichment but not with browning. Interestingly, nutrient-enrichment counteracted the negative effects of browning when combined. Our findings add novel understandings about the potential for both eutrophication and browning to affect coastal food webs and fish body growth in the Baltic Sea.
|
|
| 13. |
- Bergström, Lena, et al.
(författare)
-
Coastal fish indicators response to natural and anthropogenic drivers-variability at temporal and different spatial scales
- 2016
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 183, s. 62-72
-
Tidskriftsartikel (refereegranskat)abstract
- Ecological indicators are increasingly used in marine and freshwater management but only few are developed towards full operationalization with known patterns of variability and documented responses to natural and anthropogenic environmental drivers. Here, we evaluate potential sources of indicator variability at two different spatial scales in three coastal fish-based indicators of environmental status in the Baltic Sea; abundance of cyprinids, abundance of perch and the proportion of larger perch. The study was performed on a data set covering 41 monitoring areas subject to different levels of anthropogenic impact, at a latitudinal range of 56-66 degrees N and a salinity range of 2-8. Interannual variation was clearly minor relative to spatial variation. Small-scale spatial variation was related to water depth, wave exposure and water temperature. The remaining variation was assessed in relation to differences in natural and anthropogenic drivers between monitoring areas. Cyprinids showed a clear inverse relationship to water transparency, which was used as a proxy for eutrophication, indicating increased abundances in nutrient enriched areas. None of the indicators showed an expected negative relationship to the level of coastal commercial fisheries catches. Rather, a positive relationship for Perch suggested that the coastal fisheries were concentrated to areas with strong perch populations in the studied areas. The effect of salinity and climate (temperature during the growth season) among monitoring areas were small. The results emphasize the importance of assigning area-specific boundary levels to define good environmental status in the coastal fish indicators, in order to account for natural sources of variability. Further, although long-term monitoring in reference areas is crucial for obtaining a historical baseline, our results suggest that the status assessment of coastal fish would generally gain precision by increasingly including spatially based assessments. We propose that similar analytical approaches could be applied to other ecosystem components, especially in naturally heterogenic environments, in order to separate indicator variability attributed to potential anthropogenic impact. (C) 2016 The Authors. Published by Elsevier Ltd.
|
|
| 14. |
- Bergström, Lena, et al.
(författare)
-
Long term changes in the status of coastal fish in the Baltic Sea
- 2016
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 169, s. 74-84
-
Tidskriftsartikel (refereegranskat)abstract
- Management for sustainable coastal ecosystems is benefited by coherent large scale status assessments to support the identification of measures, but these efforts may be challenged by both data availability and natural biogeographical variation. Coastal fish are a resource for commercial and recreational fisheries as well as significant contributors to coastal ecosystem functioning, by linking lower and higher levels of the food web. This study addresses long term changes in coastal fish communities at Baltic Sea regional scale, in order to identify overall trends and support the operationalization of large scale status assessments of marine biota. The study was focused on two indicators representing the functional groups of Piscivores, which are attributed to changes in food web processes including predation/fisheries, and Cyprinids, which are associated with eutrophication. The indicators were assessed for trends within ten-year intervals, using data combined from national monitoring programs during 1991-2013. The results showed predominantly declining trends in Piscivores and of increases in Cyprinids during the studied three decades, both indicative of a deteriorating status. The pattern was however reversed in the most recent years. Similar results among adjacent areas were identified in some cases, but overall differences at local scale were high, indicating strong influence of local processes. The results suggest that coordinated local measures in order to abate cumulative effects are a preferred way of improving the overall status of coastal fish. The latest studied time intervals were the overall most stable and could be considered as potential baseline years for upcoming regional assessments. (C) 2015 Elsevier Ltd. All rights reserved.
|
|
| 15. |
- Bergström, Per, 1980, et al.
(författare)
-
Environmental influence on mussel (Mytilus edulis) growth - A quantile regression approach
- 2016
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 171, s. 123-132
-
Tidskriftsartikel (refereegranskat)abstract
- The need for methods for sustainable management and use of coastal ecosystems has increased in the last century. A key aspect for obtaining ecologically and economically sustainable aquaculture in threatened coastal areas is the requirement of geographic information of growth and potential production capacity. Growth varies over time and space and depends on a complex pattern of interactions between the bivalve and a diverse range of environmental factors (e.g. temperature, salinity, food availability). Understanding these processes and modelling the environmental control of bivalve growth has been central in aquaculture. In contrast to the most conventional modelling techniques, quantile regression can handle cases where not all factors are measured and provide the possibility to estimate the effect at different levels of the response distribution and give therefore a more complete picture of the relationship between environmental factors and biological response. Observation of the relationships between environmental factors and growth of the bivalve Mytilus edulis revealed relationships that varied both among level of growth rate and within the range of environmental variables along the Swedish west coast. The strongest patterns were found for water oxygen concentration level which had a negative effect on growth for all oxygen levels and growth levels. However, these patterns coincided with differences in growth among periods and very little of the remaining variability within periods could be explained indicating that interactive processes masked the importance of the individual variables. By using quantile regression and local regression (LOESS) this study was able to provide valuable information on environmental factors influencing the growth of M. edulis and important insight for the development of ecosystem based management tools of aquaculture activities, its use in mitigation efforts and successful management of human use of coastal areas. © 2016 Elsevier Ltd.
|
|
| 16. |
- Bergström, Per, 1980, et al.
(författare)
-
Temporal consistency of spatial pattern in growth of the mussel, Mytilus edulis: Implications for predictive modelling
- 2013
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 131, s. 93-102
-
Tidskriftsartikel (refereegranskat)abstract
- Human pressures on coastal seas are increasing and methods for sustainable management, including spatial planning and mitigative actions, are therefore needed. In coastal areas worldwide, the development of mussel farming as an economically and ecologically sustainable industry requires geographic information on the growth and potential production capacity. In practice this means that coherent maps of temporally stable spatial patterns of growth need to be available in the planning process and that maps need to be based on mechanistic or empirical models. Therefore, as a first step towards development of models of growth, we assessed empirically the fundamental requirement that there are temporally consistent spatial patterns of growth in the blue mussel, Mytilus edulis. Using a pilot study we designed and dimensioned a transplant experiment, where the spatial consistency in the growth of mussels was evaluated at two resolutions. We found strong temporal and scale-dependent spatial variability in growth but patterns suggested that spatial patterns were uncoupled between growth of shell and that of soft tissue. Spatial patterns of shell growth were complex and largely inconsistent among years. Importantly, however, the growth of soft tissue was qualitatively consistent among years at the scale of km. The results suggest that processes affecting the whole coastal area cause substantial differences in growth of soft tissue among years but that factors varying at the scale of km create strong and persistent spatial patterns of growth, with a potential doubling of productivity by identifying the most suitable locations. We conclude that the observed spatial consistency provides a basis for further development of predictive modelling and mapping of soft tissue growth in these coastal areas. Potential causes of observed patterns, consequences for mussel-farming as a tool for mitigating eutrophication, aspects of precision of modelling and sampling of mussel growth as well as ecological functions in general are discussed. © 2013 Elsevier Ltd.
|
|
| 17. |
- Bergström, Ulf, et al.
(författare)
-
Stickleback increase in the Baltic Sea - A thorny issue for coastal predatory fish
- 2015
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 163, s. 134-142
-
Tidskriftsartikel (refereegranskat)abstract
- In the Baltic Sea, the mesopredator three-spined stickleback (Gasterosteus aculeatus) spends a large part of its life cycle in the open sea, but reproduces in shallow coastal habitats. In coastal waters, it may occur in high abundances, is a potent predator on eggs and larvae of fish, and has been shown to induce trophic cascades with resulting eutrophication symptoms through regulation of invertebrate grazers. Despite its potential significance for the coastal food web, little is known about its life history and population ecology. This paper provides a description of life history traits, migration patterns and spatiotemporal development of the species in the Baltic Sea during the past decades, and tests the hypothesis that stickleback may have a negative impact on populations of coastal predatory fish. Offshore and coastal data during the last 30 years show that stickleback has increased fourfold in the Bothnian Sea, 45-fold in the Central Baltic Sea and sevenfold in the Southern Baltic Sea. The abundances are similar in the two northern basins, and two orders of magnitude lower in the Southern Baltic Sea. The coastward spawning migration of sticklebacks from offshore areas peaks in early May, with most spawners being two years of age at a mean length of 65 mm. The early juvenile stage is spent at the coast, whereafter sticklebacks perform a seaward feeding migration in early autumn at a size of around 35 mm. A negative spatial relation between the abundance of stickleback and early life stages of perch and pike at coastal spawning areas was observed in spatial survey data, indicating strong interactions between the species. A negative temporal relationship was observed also between adult perch and stickleback in coastal fish monitoring programmes supporting the hypothesis that stickleback may have negative population level effects on coastal fish predators. The recent increase in stickleback populations in different basins of the Baltic Sea in combination with negative spatiotemporal patterns and previously observed interactions between stickleback and coastal predatory fish suggests that this species may have gained a key role in the coastal food webs of the Baltic Sea. Through its migrations, stickleback may also constitute an important vector linking coastal and open sea ecosystem dynamics. (c) 2015 Elsevier Ltd. All rights reserved.
|
|
| 18. |
- Berkström, Charlotte, 1978-, et al.
(författare)
-
Exploring 'knowns' and 'unknowns' in tropical seascape connectivity with insights from East African coral reefs
- 2012
-
Ingår i: Estuarine Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 107, s. 1-21
-
Tidskriftsartikel (refereegranskat)abstract
- Applying a broader landscape perspective to understand spatio-temporal changes in local populations and communities has been increasingly used in terrestrial systems to study effects of human impact and land use change. With today's major declines in fishery stocks and rapid degradation of natural coastal habitats, the understanding of habitat configuration and connectivity over relevant temporal and spatial scales is critical for conservation and fisheries management of the seascape. Coral reefs, seagrass beds and mangroves are key-components of the tropical seascape. The spatial distribution of these habitat types may have strong influences on cross-habitat migration and connectivity patterns among organisms. However, the consequences of seascape fragmentation and ecological connectivity are largely unknown. Here, we review the literature to provide an overview of current knowledge with regards to connectivity and food-web interactions within the tropical seascape. We show that information on fish acting as mobile links and being part of nutrient transfer and trophic interactions is scarce. We continue by making an in-depth analysis of the seascape around Zanzibar (Eastern Africa) to fill some of the knowledge gaps identified by the literature survey. Our analysis shows that (i) fifty percent of all fish species found within the Zanzibar seascape use two or multiple habitat types, (ii) eighteen percent of all coral reef-associated fish species use mangrove and seagrass beds as juvenile habitat, and (iii) macrocarnivores and herbivores are highly represented among those coral reef fish species that use mangrove and seagrass beds as juvenile habitat. We argue that understanding the inter-linkages within and between habitat types is essential for successful management of the tropical seascape. (c) 2012 Elsevier Ltd. All rights reserved
|
|
| 19. |
- Burdorf, Laurine D.W., et al.
(författare)
-
Electrogenic sulfur oxidation by cable bacteria in two seasonally hypoxic coastal systems
- 2024
-
Ingår i: Estuarine, Coastal and Shelf Science. - 0272-7714 .- 1096-0015. ; 297
-
Tidskriftsartikel (refereegranskat)abstract
- Cable bacteria can reach high densities in coastal sediments, and as a result of their unusual electrogenic lifestyle and intense metabolic activity, exert a major and distinct impact on biogeochemical cycling, both locally in sediments and at the ecosystem level. This appears to be particularly true for seasonally hypoxic systems, but the driving force behind the proliferation of cable bacteria in these systems is not well understood. Moreover, the metabolism of cable bacteria induces strong acid production, which can be buffered through carbonate dissolution in sediments. A strong depletion of alkalinity in the pore water is therefore expected in carbonate-poor sediments. To evaluate the impact of cable bacteria metabolism on sediment geochemistry, we performed field sampling and laboratory sediment incubations in two seasonally hypoxic sites: one carbonate-poor site with low levels of free sulfide in pore water (Yarra Estuary, Australia) and one carbonate-rich site with high free sulfide (Lake Grevelingen, The Netherlands). Active cable bacteria populations were found in both field locations, with higher abundance and activity observed in spring compared to autumn. The sediment incubations tracked the metabolic activity of cable bacteria over time (maximum 84 days), and confirmed the fast development of an electric network (cell doubling time: ∼19 h). These results suggest that cable bacteria are widespread in seasonally hypoxic systems, supporting previous findings. Cable bacteria acidified the sediment by > 1.5 pH units in 6–13 days (differing per site) and their activity accounted for >70% of the oxygen uptake. A clear subsurface accumulation of Fe2+ was observed after 8 days of Yarra sediment incubations, indicative of increased FeS dissolution as e-SOx developed. The increased availability of sulfide from FeS dissolution promotes a positive-feedback loop that we infer allowed for a faster development of cable bacteria in the carbonate-poor sediments. A depletion of total alkalinity was observed in the deeper Yarra sediment, whereas, a higher alkalinity efflux was previously observed in the carbonate-rich sediments from Lake Grevelingen. These results suggest a differential pH and alkalinity dynamic due to the interaction between the local carbonate content of the sediment and cable bacteria activity.
|
|
| 20. |
- Båmstedt, Ulf
(författare)
-
Decomposing medusae as substrata for bacterial growth and their potential contribution to environmental hypoxia
- 2022
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Academic Press. - 0272-7714 .- 1096-0015. ; 276
-
Tidskriftsartikel (refereegranskat)abstract
- Decomposing jellyfishes at 9ᵒC showed exponential loss in wet and dry weight, particulate (POC) and dissolved (DOC) organic carbon and particulate organic nitrogen (PON), with turnover times of 3.5–4.2 d. The amount (%) carbon and nitrogen of carcasses, decreased linearly over time, but the C/N atomic ratio remained stable at 7. The daily decline of POC and PON, as a % of starting C and N, both showed a negative relationship with medusa weight, but with a stable POC/PON atomic ratio at 9.1. Five morphological groups of bacteria that co-occurred with the medusa, all exhibited exponential growth, with an average daily biomass doubling rate between 2.8 and 4.9. Over a 3-d period the biomass ratio between coccoids and spirills increased by a factor of 76. Oxygen consumption in the surrounding water was on average 0.34 ± 0.10 mg l−1 h−1 and slightly increasing over time. Assuming the oxygen consumption being a function of bacterial respiration, the bacterial growth efficiency increased exponentially from <3% during the first 25 h to 16% after 55 h. Incorporating all of these results, the potential impact of decomposing jellyfishes on environmental oxygen concentration could be simulated, with the biomass of decomposing medusae and water-mixing volume as input variables. Such simulations would be useful to forecast environmental hypoxia.
|
|
| 21. |
- Båmstedt, Ulf
(författare)
-
Life history traits of the deep-water medusa Periphylla periphylla as revealed through failure and recovery of recruitment
- 2023
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier. - 0272-7714 .- 1096-0015. ; 282
-
Tidskriftsartikel (refereegranskat)abstract
- Extended recruitment failure and subsequent success of the coronate medusa Periphylla periphylla in a Norwegian fjord provided a unique opportunity to estimate age-related biological traits by combining individual size distribution in the population over time with previously published data. The average growth rate decreased exponentially with age, from 0.55% day−1 during the first year to <0.17% day−1 after four years. This species becomes mature at the third year, when females carry approximately 10 mature oocytes. At an age of 9 years, the medusa is on average 12 cm in diameter and carries over 1000 mature oocytes. Recruitment of juveniles, 0.5–1 cm diameter, was estimated to be 15 female−1 year−1 in Halsafjord; mortality from egg to juvenile 1 cm in diameter, using oocyte turnover times (T) of 1–12 months, was 93% (T = 12 months) to 99.95% (T = 1 month). Eggs and juveniles younger than 10 months are not capable of vertical migration and remain deeper than the sill depth where regular fjord circulation occurs. Therefore they are only vulnerable to deep-water renewal, and a fjord population of P. periphylla is estimated to gradually decrease recruitment with increased frequency of deep-water renewal and reach zero recruitment with renewal intervals of 10 months or less. It is hypothesized that differences in regular and intermittent deep-water renewal is the main factor causing variability in size (age) distribution between fjord populations.
|
|
| 22. |
- Camenen, Benoit, et al.
(författare)
-
A general formula for non-cohesive bed load sediment transport
- 2005
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 1096-0015 .- 0272-7714. ; 63:1-2, s. 249-260
-
Tidskriftsartikel (refereegranskat)abstract
- A bed load transport formula for non-cohesive sediment, based on the bed-shear concept of Meyer-Peter and Muller, was developed and validated for steady flows, oscillatory flows, and combined steady and oscillatory flows. The bed load formula introduced in this study was examined using data from experimental and field measurements for a wide range of flows and sediment conditions, as occurring in river, coastal, and marine environments. More than 1000 steady and 500 oscillatory flow cases were used in the study. The relationship between the bed load transport and the total Shields parameter to the power 1.5 was first confirmed for the steady flows. An exponential factor to take into account the effect of the critical Shields parameter was introduced. The proposed formula for the steady current was expanded and generalized to take into account the effects of oscillatory flows as well as oscillatory flows with a superimposed current at an arbitrary angle. The time-dependent bed load transport was treated in a "quasisteady" manner using the quadratic value of the instantaneous Shields parameter for the two half-periods of the wave (when the total instantaneous velocity u is in the direction of the wave, u > 0, or in the opposite direction, u < 0). A good correlation was found between the bed load formula and the measurements for colinear oscillatory and steady flows when no phase-lag occurred in the experiments. However, a marked scatter was observed since the Shields parameter had to be estimated and not derived directly from measured data. Finally, the validity and limitations of the obtained bed load transport formula are discussed.
|
|
| 23. |
- Camenen, Benoit, et al.
(författare)
-
Equivalent roughness height for plane bed under oscillatory flow
- 2009
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 1096-0015 .- 0272-7714. ; 81:3, s. 409-422
-
Tidskriftsartikel (refereegranskat)abstract
- A new relationship between the roughness height and the main hydrodynamic and sediment parameters for plane beds under oscillatory conditions is presented. In order to derive such a relationship, a large data base encompassing plane-bed experiments was compiled from previous investigations and analyzed. Different methods to estimate the roughness height were investigated. Comparisons between the data and different existing predictive formulas for the bed roughness obtained from the literature were also performed. A relationship involving the grain size and Shields parameter only, which is commonly proposed, appeared to be insufficient to characterize the roughness. The roughness height was also found to be a function of the sediment density and the settling velocity. A critical Shields parameter was identified up to which the effective roughness ratio is proportional to the Shields parameter only. The new empirical equation developed in this study provides the highest predictive skill for all conditions investigated. (c) 2008 Elsevier Ltd. All rights reserved.
|
|
| 24. |
- Cardinale, Massimiliano, et al.
(författare)
-
The community structure of over-wintering larval and small juvenile fish in a large estuary
- 2014
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 139, s. 27-39
-
Tidskriftsartikel (refereegranskat)abstract
- The Skagerrak and Kattegat are estuarine straits of high hydrographical and ecological diversity, situated between the saline waters of the North Sea and the brackish waters of the Baltic Sea. These sustain important nursery grounds of many fish species, of which several oveminter during the larval and early juvenile stages. In order to give more insight into the communities of the overwintering ichthyoplankton in estuarine areas, we examine an annual series of observations from a standard survey carried out 1992 -2010. Species differences and annual variability in distributions and abundances are described, and linkages between ichthyoplankton abundances and corresponding hydrographical information are analysed by GAM methods. Communities were dominated by herring, gobies, butterfish, sprat, pipe-fishes, lemon sole and European eel (i.e. glass eel), and all the sampled species showed large annual fluctuations in abundances. The species showed quite specific patterns of distribution although species assemblages with common distributional characteristics were identified. Within these assemblages, the ichthyoplankton abundances showed linkage to environmental characteristics described by bottom-depth and surface temperature and salinity. Hence the study points to a significant structuring of overwintering ichthyoplankton communities in large estuaries, based on the species habitat choice and its response to physical gradients. (C) 2014 Elsevier Ltd. All rights reserved.
|
|
| 25. |
|
|
| 26. |
- Corell, Hanna, et al.
(författare)
-
Sediment suspended by bottom trawling can reduce reproductive success in a broadcast spawning fish
- 2023
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 282
-
Tidskriftsartikel (refereegranskat)abstract
- Suspended sediment adheres to pelagic fish eggs, affecting their buoyancy. In the stratified southern Baltic Sea, eggs of the Eastern cod depend on neutral buoyancy in the “reproductive volume” (RV) (approx. >11 salinity and >2 ml O2/L) for successful hatching. With increased suspended sediment concentrations (SSC), eggs risk sinking out of the RV into deeper, unfavourable conditions. Bottom trawling, which increases SSC, has been intense around the Eastern cod spawning ground. We modelled the transport of sediment suspended from trawling at this spawning ground to estimate the degree to which eggs could be affected by increased SSC. SSC >1 mg/L above background levels was found 3 km away, one trawl track subjecting a water volume equivalent to 0.01% of the RV to this excess SSC for >12 h. At this excess SSC, it would take c. 6 d for an egg to sink out into unfavourable conditions; insufficient time for it to become a larva. Extrapolating to real bottom trawling intensities in the area of the RV where suspension is highest showed that a water volume equivalent to half the RV experiences excess turbidity of >1 mg/L for c. 24 h during a year. However, fishing effort is heterogeneous; spatio-temporal overlap between trawling and the RV will enhance the duration and/or frequency of turbidity in the spawning area, affecting a higher fraction of the eggs than the model predicts. We conclude that bottom trawling at this spawning ground could decrease cod's reproductive success through increased SSC. Such effects are likely in populations of other fish with pelagic eggs that spawn at trawling grounds.
|
|
| 27. |
- Crona, Beatrice, et al.
(författare)
-
Community structure and temporal variability of juvenile fish assemblages in natural and replanted mangroves, Sonneratia alba Sm., of Gazi Bay, Kenya
- 2007
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 74:1-2, s. 44-52
-
Tidskriftsartikel (refereegranskat)abstract
- The juvenile fish community associated with natural, degraded and replanted Sonneratia alba mangroves in Gazi Bay was sampled during the South East and North East monsoons between April 2002 and June 2003. A total of 1800 individuals belonging to 49 taxa and 34 families were collected from the intertidal forest using stake nets. Fish abundance ranged from 0.93 ± 0.20 ind. m−2 (SEM02) to 1.16 ± 0.18 ind. m−2 (SEM03) between seasons and between 0.54 ± 0.07 ind. m−2 and 1.64 ± 0.33 ind. m−2 for individual sites across seasons. Five taxa accounted for approximately 70% of the total fish abundance, with Gobidae and Gerres oyena dominating. ANOSIM revealed seasonal differences in fish species composition and abundance (p = 0.01) due to fluctuating abundances of primarily Terapon sp. and Thryssa sp. The majority (65%) of fishes were reef associates, which implies a tight coupling between mangroves and coral reefs. The high proportion (75%) of commercial species indicates that fringing S. alba mangroves of Gazi Bay are important in sustaining coastal fisheries in the area. The fact that the replanted mangroves of Gazi Bay harbor a significant number of commercially important species as juveniles suggest their function as nursery habitats for nekton may well have been restored. This study is original in quantitatively evaluating the use of replanted intertidal mangroves by juvenile fish in the West Indian Ocean; a topic poorly studied worldwide to date.
|
|
| 28. |
- Crona, Beatrice, et al.
(författare)
-
Use of replanted mangroves as nursery grounds by shrimp communities in Gazi Bay, Kenya
- 2005
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 65:3, s. 535-544
-
Tidskriftsartikel (refereegranskat)abstract
- This study quantitatively assessed the distribution of postlarval and juvenile shrimps in natural, degraded and replanted stands of Sonneratia alba mangroves in Gazi Bay, Kenya in 2002–2003. Two plantations (matrix and integrated) differing in historical status and planting strategy were studied. Sampling was conducted using stake nets (2 mm mesh), each net enclosing 9 m2 of intertidal microhabitat. A total of 615 shrimps from 19 species/taxa were caught, including several penaeid species of major commercial importance. Penaeids dominated the catch (66%) followed by Macrobrachium spp. (16%) and Acetes sp. (6%). Shrimp abundance ranged from 0.42 to 10.0 ind. per net (9 m2) for individual sites across spring tides and significant differences were detected between sites and over time (p<0.001). Results showed no significant difference in diversity of species/taxa between sites. However, multivariate analysis revealed significant differences in community assemblages between sites, except for the natural stand and integrated plantation. These two sites harbored higher abundances of the majority of all taxa caught. The observed distribution patterns are discussed with regard to measured environmental parameters such as elevation, structural complexity and sediment characteristics.
|
|
| 29. |
|
|
| 30. |
- Das, Saudamini, et al.
(författare)
-
Mangroves can provide protection against wind damage during storms
- 2013
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 134, s. 98-107
-
Tidskriftsartikel (refereegranskat)abstract
- Research has established that mangroves can protect lives and property from storms by buffering the impacts of storm surges. However, their effects in attenuating wind velocity and providing protection from wind damage during storms are not known. This study examined whether mangroves attenuate damage from cyclonic winds and found that they provide substantial protection to properties, even relatively far away from mangroves and the coast. We devised a theoretical model of wind protection by mangroves and calibrated and applied this model using data from the 1999 cyclone in the Odisha region of India. The model predicted and quantified the actual level of damage reasonably accurately and showed that mangroves reduced wind damage to houses. The wind protection value of mangroves in reducing house damage amounted to approximately US$177 per hectare at 1999 prices. This provides additional evidence of the storm protection ecosystem services that mangroves supply in the region and an additional reason to invest in mangrove ecosystems to provide better adaptability to coastal disasters such as storms.
|
|
| 31. |
- Donadi, Serena, et al.
(författare)
-
Perch and pike recruitment in coastal bays limited by stickleback predation and environmental forcing
- 2020
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 246
-
Tidskriftsartikel (refereegranskat)abstract
- Role reversal can shift fish communities from predator to prey dominance. In the Baltic Sea, the increase in abundance of the small-bodied three-spined stickleback (Gasterosteus aculeatus) has co-occurred with declines of coastal predatory fish, such as perch (Perca fluviatilis) and pike (Esox lucius) in many areas. Recent studies have pointed at predator-prey reversal as a possible mechanism explaining these trends, but conclusive evidence on the phenomenon or its relative importance compared to other drivers is at present open to question. In this study, we applied path analysis to quantify the potential role of stickleback in limiting the recruitment of perch and pike in enclosed bays (i.e. flads) along the Swedish and Finnish coasts. We constructed a causal network model based on vast field data combined with data from GIS and orthophotos, representing fish abundance, hydrographic factors, habitat-forming vegetation, anthropogenic disturbances and geomorphological factors. We found that stickleback abundance had as large effect on larval densities of perch and pike as environmental forcing, represented in our best models by the thermal regime of the flads. Larval densities decreased with stickleback abundance and increased with increasing summer cumulative temperature at a similar rate. Stickleback abundance, in turn, was strongly limited by flad openness, expressed as the number of flad openings to the sea, and increased with vascular plant cover (flad averages). Our study shows that predator-prey reversal could be a strong determinant of perch and pike larval survival, and suggests that the prevalence of more enclosed flads, which are less accessible to stickleback, may be crucial for recruitment of these piscivores. This implies that (1) in areas with, or prone to, increased stickleback abundance, habitat restoration and actions to conserve piscivore populations should primarily focus on more enclosed flads, and that (2) dredging and canalization to enhance boating in these areas could have detrimental effects on piscivore recruitment by decreasing water temperature and enhancing stickleback abundance, hence restricting larval growth and survival.
|
|
| 32. |
- Eggertsen, Linda, et al.
(författare)
-
Seaweed beds support more juvenile reef fish than seagrass beds in a south-western Atlantic tropical seascape
- 2017
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 196:5, s. 97-108
-
Tidskriftsartikel (refereegranskat)abstract
- Seascape connectivity is regarded essential for healthy reef fish communities in tropical shallow systems. A number of reef fish species use separate adult and nursery habitats, and hence contribute to nutrient and energy transfer between habitats. Seagrass beds and mangroves often constitute important nursery habitats, with high structural complexity and protection from predation. Here, we investigated if reef fish assemblages in the tropical south-western Atlantic demonstrate ontogenetic habitat connectivity and identify possible nurseries on three reef systems along the eastern Brazilian coast. Fish were surveyed in fore reef, back reef, Halodule wrightii seagrass beds and seaweed beds. Seagrass beds contained lower abundances and species richness of fish than expected, while Sargassum-dominated seaweed beds contained significantly more juveniles than all other habitats (average juvenile fish densities: 32.6 per 40 m2 in Sargassum beds, 11.2 per 40 m2 in back reef, 10.1 per 40 m2 in fore reef, and 5.04 per 40 m2 in seagrass beds), including several species that are found in the reef habitats as adults. Species that in other regions worldwide (e.g. the Caribbean) utilise seagrass beds as nursery habitats were here instead observed in Sargassum beds or back reef habitats. Coral cover was not correlated to adult fish distribution patterns; instead, type of turf was an important variable. Connectivity, and thus pathways of nutrient transfer, seems to function differently in east Brazil compared to many tropical regions. Sargassum-dominated beds might be more important as nurseries for a larger number of fish species than seagrass beds. Due to the low abundance of structurally complex seagrass beds we suggest that seaweed beds might influence adult reef fish abundances, being essential for several keystone species of reef fish in the tropical south-western Atlantic.
|
|
| 33. |
- Eggertsen, Linda, 1981-, et al.
(författare)
-
Where the grass is greenest in seagrass seascapes depends on life history and simple species traits of fish
- 2022
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Academic Press. - 0272-7714 .- 1096-0015. ; 266
-
Tidskriftsartikel (refereegranskat)abstract
- Tropical seagrass meadows are critical habitats for many fish species, yet few studies have investigated the influence of multiple scale-dependent factors and marine protected areas on seagrass fish species of differing life histories. We assessed the influence of fine-scale seagrass meadow characteristics and seascape-scale variables on the abundance of fish in a seagrass-dominated seascape in the Bazaruto Archipelago, Mozambique, particularly examining patterns of nursery- vs. resident species as well as mobile- vs. sedentary species. We found that fish distribution patterns in this seagrass-dominated seascape were dependent on species’ life history characteristics; nursery taxa showed lower abundance in seagrass meadows further from adult reef habitats, while resident species within seagrass meadows occurred in higher abundances far from reefs. For taxa utilizing both mangroves and seagrass meadows as nursery habitat, proximity to mangroves was an important factor. Fish abundances were generally influenced by variables at the seascape scale (km), while sedentary species were predominantly influenced by area variables, and smaller seascapes (<500 m in radius) better explained distribution patterns. The influence of marine protected areas was taxon-specific, with the strongest effects of protection on resident species. Our results indicate that protection efforts in seagrass-dominated seascapes can have varying impacts on fish distribution, depending on the life history of the species present, and the geographical placement of the reserve within the seascape. Further, we suggest that simple species attributes can be utilised to describe generalized abundance patterns of fish in seagrass seascapes.
|
|
| 34. |
- Eklund, Britta
(författare)
-
Review of the use of Ceramium tenuicorne growth inhibition test for testing toxicity of substances, effluents, products sediment and soil
- 2017
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 195, s. 88-97
-
Tidskriftsartikel (refereegranskat)abstract
- A growth inhibition test has been developed based on two clones of the red macroalga Ceramium tenuicorne, one originating from 7 PSU and the other from 20 PSU. The species can be adapted to different salinities and the test can be carried out between 4 and 32 PSU. This test became an ISO standard in 2010 (ISO 107 10) for testing of chemicals and water effluents. In this study new and published data has been compiled on toxicity of single substances, waste waters from pulp mills, leachates from antifouling paints, harbour sediments and soil used for maintenance of leisure boats. The results show that the alga is sensitive to both metals and organic compounds and to biocides used in antifouling paints. By testing leachates from antifouling paints these could be ranked according to their toxicity. Similarly, the toxicity of waste waters from pulp mills was determined and the efficiency of secondary treatment evaluated. Further, the test method proved useful to test the toxicity in sediment samples. Sediments from small town harbours and ship lanes were shown to be harmful and compounds originating from antifouling paints were responsible for a large part of the inhibiting effect. The alga proved to be sensitive to contaminants leaking from boat yard soil. The growth inhibition test is a robust test that has high repeatability and reproducibility and easily can be applied on water, soil and sediment samples without being too costly. The species is found wort-wide in temperate waters, which makes the results relevant for large areas. In the Baltic Sea C tenuicorne is the most common red alga species and is thus particularly relevant for this area. The overall results show that contaminants from boat activities and the use of antifouling paints in particular pose a threat to the environment.
|
|
| 35. |
- Eklund, B., et al.
(författare)
-
Toxic effects of decomposing red algae on littoral organisms
- 2005
-
Ingår i: Estuarine, Coastal and Shelf Science. - 0272-7714 .- 1096-0015. ; 62:4, s. 621-626
-
Tidskriftsartikel (refereegranskat)abstract
- Large masses of filamentous red algae of the genera Polysiphonia, Rhodomela, and Ceramium are regularly washed up on beaches of the central Baltic Sea. As the algal masses start to decay, red coloured effluents leak into the water, and this tinge may be traced several hundred meters off shore. In this study, possible toxic effects of these effluents were tested on littoral organisms from different trophic levels. Effects on fertilisation, germination and juvenile survival of the brown seaweed Fucus vesiculosus were investigated, and mortality tests were performed on the crustaceans Artemia salina and Idotea baltica, as well as on larvae and adults of the fish Pomatoschistus microps. Fucus vesiculosus was the most sensitive species of the tested organisms to the red algal extract. The survival of F. vesiculosus recruits was reduced with 50% (LC50) when exposed to a concentration corresponding to 1.7 g l(-1) dw red algae. The lethal concentration for L baltica, A. salina and P. microps were approximately ten times higher. The toxicity to A. salina was reduced if the algal extract was left to decompose during two weeks but the decline in toxicity was not affected by different light or temperature conditions. This study indicates that the filamentous red algae in the central Baltic Sea may produce and release compounds with negative effects on the littoral ecosystem. The effects may be particularly serious for the key species F. vesiculosus, which reproduce in autumn when filamentous red algal blooms are most severe. (C) 2004 Elsevier Ltd. All rights reserved.
|
|
| 36. |
- Eklöf, J.S., et al.
(författare)
-
Sea urchin overgrazing of seagrasses: A review of current knowledge on causes, consequences and management
- 2008
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 79:4, s. 569-580
-
Tidskriftsartikel (refereegranskat)abstract
- Sea urchins are one of the most common seagrass macro-grazers in contemporary seagrass systems. Occasionally their grazing rates exceed seagrass growth rates, a phenomenon sometimes referred to as overgrazing. Because of a reported increasing frequency of overgrazing events, concomitant with loss of seagrass-associated ecosystem services, it has been suggested that overgrazing is one of the key threats to tropical and subtropical seagrasses. In light of this, we review the current knowledge on causes, consequences. and management of sea urchin overgrazing of seagrasses. Initially we argue that the definition of overgrazing must include scale and impairment of ecosystem services, since this is the de facto definition used in the literature, and will highlight the potential societal costs of seagrass overgrazing. A review of 16 identified cases suggests that urchin overgrazing is a global phenomenon, ranging from temperate to tropical coastal waters and involving at least 11 seagrass and 7 urchin species. Even though most overgrazing events Seem to affect areas of <0.5 km(2), and recovery often occurs within a few years, overgrazing can have a range of large, long-term indirect effects such as loss of associated fauna and decreased sediment stabilization. A range of drivers behind overgrazing have been suggested, including bottom-up (nutrient enrichment). top-down (reduced predation control due to e.g. overfishing), "side-in" mechanisms (e.g. changes in water temperature) and natural population fluctuations. Based on recent studies, there seems to be fairly strong support for the top-down and bottom-up hypotheses. However, many potential drivers often co-occur and interact, especially in areas with high anthropogenic pressure, suggesting that multiple disturbances-by simultaneously reducing predation control, increasing urchin recruitment and reducing the resistance of seagrasses-could pave the way for overgrazing. In management, the most common response to overgrazing has been to remove urchins, but limited knowledge of direct and indirect effects makes it difficult to assess the applicability and sustainability of this method. Based on the wide knowledge gaps, which severely limits management, we suggest that future research should focus on (1) identification and quantification of ecosystem and societal scale effects of overgrazing; (2) assessment of the relative importance and interactions of different drivers; and (3) development of a holistic proactive and reactive long-term management agenda.
|
|
| 37. |
- Engel, Friederike G., et al.
(författare)
-
Mussel beds are biological power stations on intertidal flats
- 2017
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 191, s. 21-27
-
Tidskriftsartikel (refereegranskat)abstract
- Intertidal flats are highly productive areas that support large numbers of invertebrates, fish, and birds. Benthic diatoms are essential for the function of tidal flats. They fuel the benthic food web by forming a thin photosynthesizing compartment in the top-layer of the sediment that stretches over the vast sediment flats during low tide. However, the abundance and function of the diatom film is not homogenously distributed. Recently, we have realized the importance of bivalve reefs for structuring intertidal ecosystems; by creating structures on the intertidal flats they provide habitat, reduce hydrodynamic stress and modify the surrounding sediment conditions, which promote the abundance of associated organisms. Accordingly, field studies show that high chlorophyll a concentration in the sediment co-vary with the presence of mussel beds. Here we present conclusive evidence by a manipulative experiment that mussels increase the local biomass of benthic microalgae; and relate this to increasing biomass of microalgae as well as productivity of the biofilm across a nearby mussel bed. Our results show that the ecosystem engineering properties of mussel beds transform them into hot spots for primary production on tidal flats, highlighting the importance of biological control of sedimentary systems.
|
|
| 38. |
- Engqvist, Anders, et al.
(författare)
-
Flow regimes and long-term water exchange of the Himmerfjarden estuary
- 2009
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 83:2, s. 159-174
-
Tidskriftsartikel (refereegranskat)abstract
- A numerical model of processes determining the water exchange encountered in Baltic coastal archipelagos is calibrated and validated against salinity and temperature field data spanning two decades with approximately bi-weekly resolution assessed in the Himmerfjärden estuary. This area is resolved into 17 basins interconnected by 38 individual straits of varying geometrical properties using GIS-based methods. All formulations of the strait exchange flows are free from parameters that need calibration and permit computations of the flow through a strait contraction with or without a coincident sill under a flow classification scheme, of which the first one (a) consists of two groups of multiple layers including aspirated layers from levels beneath the sill crest. The other regimes are as follows. (b) Pure barotropic flow; (c) rotationally controlled flow and (d) plug-flow, which serves as resort solution for flow situations that cannot be solved with (a) and also for computation of the barotropic part of the total flow. For long canals where friction effects act to reduce the flow, a fifth exchange regime is used. The vertical mixing formulation is based on energy balances between supplied wind energy and its work against buoyancy forces. The values of semi-empirical parameters involved in the mixing scheme have been established by calibration against measured data of the first decade period. A statistical evaluation is performed comparing the model results with the measurements of the second decade. It is found that the accuracy of the model is yet limited by the poor temporal resolution in the boundary and the thermal forcing. The overall accuracy of this approach is found to be comparable to earlier model studies in the same area. Since the exchange flows are now based on first principles and are applied to four times more basins, it seems that this more articulated model approach can confidently be applied to more complex archipelago areas.
|
|
| 39. |
- Eriksson, Britas Klemens, et al.
(författare)
-
Local distribution patterns of macroalgae in relation to environmental variables in the northern Baltic Proper
- 2005
-
Ingår i: Estuarine, Coastal and Shelf Science. - London : Academic Press. - 0272-7714 .- 1096-0015. ; 62:1-2, s. 109-117
-
Tidskriftsartikel (refereegranskat)abstract
- The relationship between macroalgal assemblages and abiotic factors was quantified by gradient analyses in an area where long-term changes in macroalgal depth distributions have previously been documented. Biomass data from 4, 6, 8 and 10 m depth in an area of similar salinity (5) and substrate (rock) in the northern Baltic Proper was constrained by a set of environmental variables defining different aspects of abiotic control of species distributions (sediment cover, effective fetch, clarity index, the curvature and slope of the bottom, and direction of exposure) in multivariate analyses at different scales. Fucus vesiculosus dominated the biomass at 4, 6 and 8 m depth, andFurcellaria lumbricalis at 10 m. The applied models explained 30.7–53.3% of the total variance in community structure, and 49.3–60.9% when analysed separately for each depth. A separate analysis of species depth distributions demonstrated that effective fetch was most strongly related to upper limits of the algal belts, sediment cover to the lower limit and density of the F. vesiculosusbelt, and clarity index to the lower limits of F. vesiculosus, perennial red algae, and of the red algal and Sphacelaria spp. belts. The results show a strong correlation between environmental variables and vegetation structure even on a small, local scale in the northern Baltic Proper, indicating a high suitability of the phytobenthic zone for environmental monitoring. The results add to previous studies that show a strong importance of abiotic factors on large-scale variation in phytobentic community composition in the Baltic Sea.
|
|
| 40. |
- Eriksson, Peder, et al.
(författare)
-
Temporal changes and spatial variation of soil oxygen consumption, nitrification and denitrification rates in a tidal salt marsh of the Lagoon of Venice, Italy
- 2003
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier. - 0272-7714 .- 1096-0015. ; 58:4, s. 861-871
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to investigate seasonal and spatial patterns of soil oxygen consumption, nitrification, denitrification and fluxes of dissolved inorganic nitrogen (DIN) in a tidal salt marsh of the Lagoon of Venice, Italy. In the salt marsh, intact soil cores including overlying water were collected monthly at high tide from April to October in salt marsh creeks and in areas covered by the dominant vegetation, Limonium serotinum. In May, cores were also collected in areas with vegetation dominated by Juncus maritimus and Halimione portulacoides. In laboratory incubations at in situ temperature in the dark, flux rates of oxygen and DIN were monitored in the overlying water of the intact cores. 15N-nitrate was added to the overlying water and nitrification and denitrification were measured using isotope-dilution and -pairing techniques. The results show that highest soil oxygen consumption coincided with the highest water temperature in June and July. The highest denitrification rates were recorded in spring and autumn coinciding with the highest nitrate concentrations. Soil oxygen consumption and nitrification rates differed between sampling sites, but denitrification rates were similar among the different vegetation types. The highest rates were recorded in areas covered with L. serotinum. Burrowing soil macrofauna enhanced oxygen consumption, nitrification and denitrification in April and May. The data presented in this study indicate high temporal as well as spatial variations in the flux of oxygen and DIN, and nitrogen transformations in the tidal salt marshes of the Venice lagoon during the growth season. The results identify the salt marshes of the Venice lagoon as being metabolically very active ecosystems with a high capacity to process nitrogen.
|
|
| 41. |
- Eriksson Wiklund, Ann-Kristin, et al.
(författare)
-
Benthic competition and population dynamics of Monoporeia affinis and Marenzelleria sp in the northern Baltic Sea
- 2014
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 144, s. 46-53
-
Tidskriftsartikel (refereegranskat)abstract
- During the last two decades major changes of the benthic fauna have occurred in the northern Baltic Sea, the Gulf of Bothnia. The native amphipod, Monoporeia affinis, has shown a large-scale abundance decrease, while polychaetes, Marenzelleria spp. have invaded the system. Marenzelleria co-exist with the native fauna in the southern Baltic Sea, but in the north the pelagic production might be too low to allow co-existence. Thus, M. affinis might have been out-competed by Marenzelleria in the Gulf of Bothnia. This hypothesis was tested in a competition experiment with a high and a low fresh phytoplankton food supply. When exposed to high food supply both species showed stable or increased biomass over the four week test period. In low food supply, however, M. affinis was found to have a competitive advantage. The experimental data were also related to Baltic Sea monitoring data on primary production, sedimentation and invertebrate abundances. Data from the northern Baltic Sea show that the dominance in the benthic community by M. affinis was replaced by Marenzelleria around 2001. The amphipod decrease might be explained by a marked decrease in primary production during this period. Combining monitoring and experimental data suggests that the invasion of Marenzelleria did not cause the decrease of M. affinis in the northern Baltic Sea; it rather took advantage of the density gap that had occurred. A shift may thus have been established in the Bothnian Sea benthic community.
|
|
| 42. |
- Eriksson Wiklund, Ann-Kristin, et al.
(författare)
-
Contaminants and habitat choice in the Baltic Sea: Behavioural experiments with the native species, Monoporeia affinis, and the invasive genus, Marenzelleria
- 2009
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 81, s. 238-246
-
Tidskriftsartikel (refereegranskat)abstract
- The invasive polychaete genus, Marenzelleria and the native amphipod, Monoporeia affinis are food and habitat competitors in the Baltic Sea. Previous studies have shown that moderate densities of Marenzelleria can affect the behaviour of M. affinis. To examine the short-term interactive effects of interspecific habitat choice and environmental contaminants a series of habitat colonisation experiments were performed. The contaminants examined included harbor sediments and sediment spiked with the antifouling substances, Cu, Zn and Irgarol. Polychaetes and amphipods were exposed to contaminants in single-species and two-species experiments. In spiked-sediment experiments, M. affinis showed clear dose-dependent response. These experiments verified that behavioural response of M. affinis to different habitats is a sensitive method for testing toxicity under controlled conditions. In experiments with three different harbor sediments and reference sediment both species showed the lowest preference for the reference sediment. This sediment also had the lowest content of quality food, indicating that factors such as food quality and quantity may override the disturbing effects of contaminants in natural sediments. The presence of Marenzelleria spp. did not affect amphipod habitat choice, indicating no short-term effects, which implies that both species can co-exist provided sufficient food is available.
|
|
| 43. |
- Erlandsson, Johan, et al.
(författare)
-
Recruit/algal interaction prevents recovery of overexploited mussel beds : Indirect evidence that post-settlement mortality structures mussel populations
- 2011
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 92:1, s. 132-139
-
Tidskriftsartikel (refereegranskat)abstract
- The mechanisms maintaining community structure following an ecosystem shift are poorly understood and we propose that they must inherently be biological. Over-exploitation can provide a natural experiment with man as a predator driving a change in community structure, possibly an ecosystem shift. We examined a possible mechanism that maintains algal beds as an alternative state on the east coast of South Africa where the mussel Perna perna has been overexploited. Even on unexploited shores, about 50% of mussel larvae settle onto algae, but it is unclear whether they later recruit into adult beds. On such shores we used two indirect field approaches to understand the fate of recruits, testing whether inhibition of mussel recruitment by macroalgae could constitute a biological mechanism preventing reversion from the algal to the pre-disturbance mussel-dominated state. First, we examined possible ontogenetic migration of recruits from algae to adult mussels, testing the prediction that the ratio large:small recruits in adult beds is greater where algae are liberally interspersed with mussels. Second, we examined whether, like adults, recruits show spatial structure that is related to the distribution of topographic depressions, testing the hypothesis that large and small recruits show different co-variation with depressions, microhabitats where algae commonly occur. We found no evidence that recruits on algae actively move to nearby mussel beds as neither the ratio large:small recruits nor the abundances of small or large recruits showed any relationship with algal cover/variability. Small and large recruits showed different co-variation with topographic depressions on spatially structured transects. Like adults, large recruits commonly exhibited negative relationships with depressions. Thus, large recruits neither occur on algae nor migrate from algae to the primary substratum or onto adult beds. Consequently our results (a) highlight the importance of post-settlement mortality in structuring these mussel populations, and (b) suggest that the interception of larvae by algae forms a biological mechanism that can maintain macroalgal beds that develop following exploitative disturbance by man, thus preventing or at least drastically delaying the natural recovery of mussel beds.
|
|
| 44. |
- Ermgassen, Philine S. E. Zu, et al.
(författare)
-
Fishers who rely on mangroves : Modelling and mapping the global intensity of mangrove-associated fisheries
- 2021
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier. - 0272-7714 .- 1096-0015. ; 248
-
Tidskriftsartikel (refereegranskat)abstract
- Mangroves are critical nursery habitats for fish and invertebrates, providing livelihoods for many coastal communities. Despite their importance, there is currently no estimate of the number of fishers engaged in mangrove associated fisheries, nor of the fishing intensity associated with mangroves at a global scale. We address these gaps by developing a global model of mangrove associated fisher numbers and mangrove fishing intensity. To develop the model, we undertook a three-round Delphi process with mangrove fisheries experts to identify the key drivers of mangrove fishing intensity. We then developed a conceptual model of intensity of mangrove fishing using those factors identified both as being important and for which appropriate global data could be found or developed. These factors were non-urban population, distance to market, distance to mangroves and other fishing grounds, and storm events. By projecting this conceptual model using geospatial datasets, we were able to estimate the number and distribution of mangrove associated fishers and the intensity of fishing in mangroves. We estimate there are 4.1 million mangrove associated fishers globally, with the highest number of mangrove fishers found in Indonesia, India, Bangladesh, Myanmar, and Brazil. Mangrove fishing intensity was greatest throughout Asia, and to a lesser extent West and Central Africa, and Central and South America.
|
|
| 45. |
- Faxneld, Suzanne, et al.
(författare)
-
Effects of elevated water temperature, reduced salinity and nutrient enrichment on the metabolism of the coral Turbinaria mesenterina
- 2010
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 88:4, s. 482-487
-
Tidskriftsartikel (refereegranskat)abstract
- Water quality is declining in many coastal areas, which has caused coral degradation worldwide. In addition, reduced water quality may aggravate the impacts of seawater temperature. In this study the effects of increased temperature (31 degrees C), nitrate enrichment (+5 mu M NO3-), low salinity (20) and combinations of these stressors were investigated compared to ambient water (25 degrees C, 30, 0.3 mu M NO3-) on the metabolism and survival of the coral Turbinaria mesenterina from the Tonkin Gulf, Vietnam. The results showed that all specimens exposed to a combination of all three stressors (i.e. high temperature + high nitrate + low salinity) died after 24 h exposure, while those that had been exposed to high nitrate + low salinity at ambient temperature did not show any effects on the metabolism or survival. Furthermore, corals exposed to low salinity + high temperature displayed a decrease in gross primary production/respiration (GP/R) ratio and the mortality rate was 50%. In addition, all corals exposed to increased temperature, alone or in combination with another stressor, displayed a GP/R-24h ratio below 1.0, suggesting that they depend on stored energy to cover their metabolic requirements. The results showed that corals may tolerate short-term exposure to stressors such as low salinity + high nitrate concentration in ambient temperature, while additional increased temperature lead to rapid mortality, hence suggesting a synergistic effect. Thus, the effect of climate change might be more severe in nearshore coastal areas where corals already are exposed to several disturbances.
|
|
| 46. |
- Ferreira, Joao G., et al.
(författare)
-
Overview of eutrophication indicators to assess environmental status within the European Marine Strategy Framework Directive
- 2011
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 93:2, s. 117-131
-
Tidskriftsartikel (refereegranskat)abstract
- In 2009, following approval of the European Marine Strategy Framework Directive (MSFD, 2008/56/EC), the European Commission (EC) created task groups to develop guidance for eleven quality descriptors that form the basis for evaluating ecosystem function. The objective was to provide European countries with practical guidelines for implementing the MSFD, and to produce a Commission Decision that encapsulated key points of the work in a legal framework. This paper presents a review of work carried out by the eutrophication task group, and reports our main findings to the scientific community. On the basis of an operational, management-oriented definition, we discuss the main methodologies that could be used for coastal and marine eutrophication assessment. Emphasis is placed on integrated approaches that account for physico-chemical and biological components, and combine both pelagic and benthic symptoms of eutrophication, in keeping with the holistic nature of the MSFD. We highlight general features that any marine eutrophication model should possess, rather than making specific recommendations. European seas range from highly eutrophic systems such as the Baltic to nutrient-poor environments such as the Aegean Sea. From a physical perspective, marine waters range from high energy environments of the north east Atlantic to the permanent vertical stratification of the Black Sea. This review aimed to encapsulate that variability, recognizing that meaningful guidance should be flexible enough to accommodate the widely differing characteristics of European seas, and that this information is potentially relevant in marine ecosystems worldwide. Given the spatial extent of the MSFD, innovative approaches are required to allow meaningful monitoring and assessment. Consequently, substantial logistic and financial challenges will drive research in areas such as remote sensing of harmful algal blooms, in situ sensor development, and mathematical models. Our review takes into account related legislation, and in particular the EU Water Framework Directive (WFD - 2000/60/EC), which deals with river basins, including estuaries and a narrow coastal strip, in order to examine these issues within the framework of integrated coastal zone management.
|
|
| 47. |
- Florin, Ann-Britt, et al.
(författare)
-
Characterisation of juvenile flatfish habitats in the Baltic Sea
- 2009
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 82:2, s. 294-300
-
Tidskriftsartikel (refereegranskat)abstract
- Survival and growth of the earliest life-stages is considered a key factor in determining the abundance of many marine fish species. For flatfishes, the availability of high quality nursery areas is essential for successful recruitment. Regarding the Baltic Sea, there are large gaps in knowledge on factors that influence the distribution of flatfishes during this sensitive stage. To identify the characteristics of important nursery areas in the Baltic for flounder (Platichthys flesus) and turbot (Psetta maxima), a field survey with push net sampling was conducted in the northern Baltic proper during autumn 2006. The sampling stations were stratified to cover several different habitat types defined by substrate and wave exposure. Apart from density of young-of-the-year (YOY) flatfishes, a number of ecological characteristics of the habitat were recorded. Physical habitat variables included substrate type, salinity, depth, turbidity, vegetation and habitat structure. Variables describing biotic processes, such as prey availability and abundance of competitors, were also sampled. The relationships between the spatial distribution of species and these ecological characteristics were fitted to presence/absence data of juvenile flatfish using generalized additive models (GAM). The best habitat descriptors for flounder in order of contribution were: substrate, habitat structure, salinity, wave exposure and occurrence of filamentous algae. Positive effects of increasing wave exposure, salinity and structure were detected while a high cover of filamentous algae had a negative effect. Sand and gravel were preferred over soft and stony substrates. For turbot the best habitat descriptors in order of contribution were: occurrence of filamentous algae, substrate and turbidity. Turbot showed a preference for areas with a low cover of filamentous algae, high turbidity and sandy substrate. Prey availability and abundance of competitors were not included in the models, indicating that the distribution of flatfishes at the scales studied (tens of kilometres) is mainly governed by physical habitat properties. These results constitute the basis for future efforts on mapping of essential flatfish habitats in the Baltic Sea.
|
|
| 48. |
- Florin, Ann-Britt, et al.
(författare)
-
Feeding habits of juvenile flatfish in relation to habitat characteristics in the Baltic Sea
- 2010
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 86:4, s. 607-612
-
Tidskriftsartikel (refereegranskat)abstract
- To investigate feeding habits of juvenile flounder (Platichthys flesus) and turbot (Psetta maxima) in relation to habitat characteristics a field survey with push net sampling was conducted in nursery areas with different ecological characteristics in the northern Baltic proper. Sampling sites were stratified to cover several different habitat types defined by substrate and wave exposure. Apart from flatfishes and epifauna, samples of macrofauna, meiofauna and hyperbenthic planktons were collected from each site together with data on vegetation, depth, salinity, temperature and turbidity. The diet differed between species where flounder diet was dominated by chironomids, copepods and oligochaetes while turbot apart from chironomids had a high incidence of amphipods, gobies and mysids. In both species there was a shift in diet with size, although this shift was influenced by the habitat. Among the environmental variables investigated, wave exposure was found to significantly influence flounder diet. Food preference in the most exposed areas was dominated by oligochaetes and copepods instead of chironomids, which dominated in sheltered areas. This study shows that habitat characteristics can have a major influence on feeding habits of juvenile flatfish.
|
|
| 49. |
- Florin, Ann-Britt, et al.
(författare)
-
Local conditions affecting current and potential distribution of the invasive round goby - Species distribution modelling with spatial constraints
- 2018
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 207, s. 359-367
-
Tidskriftsartikel (refereegranskat)abstract
- The establishment of non-indigenous species (NIS) has become a global phenomenon and is acknowledged as one of many potential threats against biodiversity and the functioning of marine ecosystems. To support effective management there is a need to predict NIS distribution and identify areas with the highest invasion risk. In this study we have developed local species distribution models by combining observations of one of the top-tier invasive NIS, the round goby Neogobius melanostomus, with high resolution maps of environmental conditions along the Baltic Sea coast of south-eastern Sweden. By applying the model with and without spatial constraints we estimate the current and potential distribution. The difference between these two maps outlines high risk areas for potential colonization, should round goby continue to spread in accordance with environmental preference in the area. We additionally highlight the significance of scale for distribution modelling by comparing the importance of local environmental conditions to variables important on a regional scale. (C) 2017 Elsevier Ltd. All rights reserved.
|
|
| 50. |
- Fonseca, Alessandra Larissa, et al.
(författare)
-
Local and meso-scale pressures in the eutrophication process of a coastal subtropical system: Challenges for effective management
- 2021
-
Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 250
-
Tidskriftsartikel (refereegranskat)abstract
- Natural and anthropogenic pressures drive coastal eutrophication worldwide, depending on the system's physical and biogeochemical dynamics in multiple spatial and temporal scales. Understanding the complexity of this process is essential to support management efforts and sustainability. Nutrients load to the Bay of Santa Catarina Island (BSCI), an important area for mollusc aquaculture, fisheries and tourism in Brazil, were assessed to identify the pressures of the eutrophication process. An updated Driver-Pressure-State-Impact-Response framework was used to facilitate the understanding of the relationship between human activities and impacts on human welfare. Pressures from runoff and effluents from combined sources resulted in inputs of 1998 t N.year−1 and 155 t P.year−1 to the system. The watersheds were characterized as meso-active to eury-active for both N and P yields. In addition to the local anthropogenic pressures, meso-scale events, such as the seasonal influence of the Plata Plume River, act as an external source of nutrients, sometimes associated with harmful algae bloom events. The results show that eutrophication and its symptoms could impact 85% of the ecosystem services of the region. Management of eutrophication at BSCI requires integrated actions between the nine municipalities of the watershed, but there are obstacles in environmental legislation and political interest to promote it. This study provides the scientific basis for stakeholders and decision-makers to establish priorities and actions in coastal municipalities to minimize eutrophication.
|
|
