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- Andersson, Agneta, et al.
(författare)
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Succession and growth limitation of phytoplankton in the Gulf of Bothnia (Baltic Sea)
- 1996
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Ingår i: Marine Biology. - 0025-3162 .- 1432-1793. ; 126:4, s. 791-801
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Tidskriftsartikel (refereegranskat)abstract
- A one year field study of four stations in the Gulf of Bothnia during 1991 showed that the biomass was ca. two times, and primary productivity ca, four times, lower in the north (Bothnian Bay) than in the south (Bothnian Sea) during the summer. Nutrient addition experiments indicated phosphorus limitation of phytoplankton in the Bothnian Bay and the coastal areas in the northern Bothnian Sea, but nitrogen limitation in the open Bothnian Sea. A positive correlation between the phosphate concentration and the production/biomass ratio of phytoplankton was demonstrated, which partly explained the differences in the specific growth rate of the phytoplankton during the summer. Differences in photosynthetic active radiation between the stations also showed a covariation with the primary productivity. The relative importance of nutrient or light limitation for photosynthetic carbon fixation could not, however, be conclusively determined from this study. Marked differences in phytoplankton species composition from north to south were also observed. The number of dominating species was higher in the Bothnian Sea than in the Bothnian Bay. The distribution of some species could be explained as due to nutrient availability (e.g. Nodularia spumigena, Aphanizomenon sp.), while salinity probably limits the distribution of some limnic as well as marine species. The potentially toxic phytoplankton N. spumigena, Dinophysis acuminata and Chrysochromulina spp. were common in the Bothnian Sea but not in the Bothnian Bay. The pico- and nanoplankton biomass during late summer was higher than previously reported due to a revised carbon/volume ratio.
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| 2. |
- Kuparinen, Jorma, et al.
(författare)
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Food web structure and function in the Gulf of Bothnia, the Baltic Sea
- 1996
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Ingår i: Ambio. - Stockholm : Swedish Royal Academy of Sciences. - 0044-7447 .- 1654-7209. ; , s. 13-21
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Tidskriftsartikel (refereegranskat)abstract
- To improve the spatio-temporal information of ecological variables, a multidisciplinary joint study between Finnish and Swedish marine scientists was conducted in the Gulf of Bothnia, 1991. The study corroborated previous reports, suggesting a markedly lower phytoplankton production and biomass of benthic fauna in the Bothnian Bay than in the Bothnian Sea, However, contrary to the general view, the offshore carbon fixation in the Bothnian Sea exceeded that at the corresponding coastal station. The results further indicated a greater importance of bacterioplankton production to the food web in the Bothnian Bay than previously assumed. The total carbon requirement of bacteria and zooplankton was estimated to exceed carbon fixation by a factor of 1.7 in the northern basin, possibly a result of the discharge of riverine organic carbon. Diversity and biomass of both fish and benthic fauna were lower in the Bothnian Bay, with benthic meiofauna being of relatively greater importance than macrofauna in this basin.
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