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111.
Tsuneo Tanaka Peter Henriksen Risto Lignell Kalle Olli Jukka Seppälä Timo Tamminen T. Frede Thingstad 《Estuaries and Coasts》2006,29(6):1226-1241
We analyzed responses of soluble reactive phosphorus (SRP), bioavailable phosphate (PO4), particulate phosphorus, turnover time of orthophosphate (Tt), and alkaline phosphatase activity (APA) to varying degrees of nutrient stress. The nutrient stress was evoked by different treatments in concentration and combination of inorganic nitrogen (N) and phosphorus (P), and labile organic carbon (glucose) to mesocosms in experiments carried out in eutrophic southern (Odense Fjord, Denmark) and northern (Tvärminne Archipelago, Finland) coastal zones of the Baltic Sea. Despite seasonal and geographical differences, similar responses were observed in both experiments. Low SRP (<100 nmol l?1), shortT t (<10 h), and increased levels of APA were observed in both N+P balanced and P deficient treatments, while the opposite trend was observed in P replete treatments. The shortestT t and the highest APA were found when glucose was combined with N treatment. Bioavailable PO4 was estimated usingT t and P uptake rates as derived from stoichiometric conversion of carbon based primary and bacterial production. With shorterT t, the PO4 pool declined to <1 nmol-P l?1, whereas the SRP background pool (difference between SRP and PO4) remained relatively constant (c. 50 nmol l?1). APA was inversely related to PO4 but not to SRP. Responses of specific APA and specific affinity for PO4 uptake, which are APA and PO4 uptake rates (inverse ofT t), respectively, normalized to the summed P biomass of phytoplankton and bacteria, responded consistently to the pattern and magnitude of nutrient limitation evoked in our experiments. Our results, together with a literature survey, suggest that both parameters can be useful in examining PO4 availability for the natural phytoplankton and bacteria community in P starved aquatic systems. 相似文献
112.
113.
During years 1980/1981–2012/2013, inter-annual variations in sea ice and snow thickness in Kemi, in the northern coast of the Gulf of Bothnia, Baltic Sea, depended on the air temperature, snow fall, and rain. Inter-annual variations in the November—April mean air temperature, accumulated total precipitation, snow fall, and rain, as well as ice and snow thickness in Kemi and ice concentration in the Gulf of Bothnia correlated with inter-annual variations of the Pacific Decadal Oscillation(PDO), Arctic Oscillation(AO), North Atlantic Oscillation(NAO), Scandinavian Pattern(SCA), and Polar / Eurasian Pattern(PEU). The strong role of PDO is a new finding. In general, the relationships with PDO were approximately equally strong as those with AO, but rain and sea ice concentration were better correlated with PDO. The correlations with PDO were, however, not persistent; for a study period since 1950 the correlations were much lower. During 1980/1981—2012/2013, also the Pacific / North American Pattern(PNA) and El Nino–Southern Oscillation(ENSO) had statistical connections with the conditions in the Gulf of Bothnia, revealed by analyzing their effects combined with those of PDO and AO. A reduced autumn sea ice area in the Arctic was related to increased rain and total precipitation in the following winter in Kemi. This correlation was significant for the Pan-Arctic sea ice area in September, October, and November, and for the November sea ice area in the Barents / Kara seas. 相似文献
114.
Timo Pisternick Julian Lilkendey Anishta Audit-Manna Danishta Dumur Neelayya Yashvin Neehaul Nils Moosdorf 《Marine Ecology》2020,41(5):e12610
The inflow of terrestrial groundwater into the ocean is increasingly recognized as an important local source of nutrients and pollutants to coastal ecosystems. Although there is evidence of a link between fresh submarine groundwater discharge (SGD)-derived nutrients and primary producer and primary consumer abundances, the effects of fresh SGD on the productivity of higher trophic levels such as ichthyofaunal communities remain unclear. To further investigate this relationship, we sampled three sites inside a coral reef lagoon in Mauritius: One site entailing six distinct groundwater springs, a site highly influenced by freshwater influx through the springs, and a strictly marine control site. Using remote underwater video surveys, we found that fish abundances were significantly higher at the groundwater springs than at the other two sampling sites.Principal component analyses showed that the springs and the spring-influenced part of the lagoon were best described by elevated water nutrient loadings, whereas the control site was characterized by higher water salinity and pH. Macroalgae cover was highest at the control site and the springs. Herbivores and invertivores dominated the fish community at the springs, in contrast to generalists at the control site. At the spring-influenced site, we mainly encountered high coral/turf algae cover and high abundances of associated fish feeding groups (territorial farmers, corallivores). Our results provide evidence of a fresh SGD-driven relationship between altered hydrography and distinct fish communities with elevated abundances at groundwater springs in a coral reef lagoon. These findings suggest that the management and assessment of secondary consumer productivity in tropical lagoons should take into account the effects of groundwater springs. 相似文献