| 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.
|
|
