Browsing by Author "Lauringson, Velda"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Eutrofeerumise mõju põhjaloomastiku kooslustele Eesti rannikumeres(2005) Lauringson, Velda; Kotta, Jonne, juhendaja; Saat, Toomas, juhendajaItem Role of suspension feeding in a brackish-water coastal sea(Tartu University Press, 2010-01-28T06:44:45Z) Lauringson, VeldaSuspension feeding is a widespread feeding mode in aquatic ecosystems. In shallow sea areas, two important groups of suspension feeders, benthic and pelagic suspension feeders, co-exist. These groups differ in many ways. Functionally, pelagic suspension feeders recycle nutrients in pelagial, while benthic suspension feeders redirect nutrients from the pelagic to the benthic system, thereby facilitating benthic production. Benthic suspension feeders attain large biomasses in systems with a good nutrient supply via upwellings or riverine inputs and a lush hydrodynamic energy, but occur at low biomasses in low-energy systems, i.e. energy poor areas lacking upwellings or direct nutrient inputs. Benthic suspension feeders are poorly studied at energy deplete areas. The present thesis aimed to evaluate the roles of benthic and pelagic suspension feeding in the low-energy systems of the brackish-water non-tidal flat Northeastern Baltic Sea. Benthic and pelagic suspension feeding rates were compared in connection to ambient environmental conditions by the means of field experiments and sampling. Impact of benthic suspension feeding on adjacent benthic biota was related to exposure, eutrophication, and sediment type. Benthic suspension feeding rates were usually much lower than pelagic ones. However, benthic suspension feeding influenced notably adjacent benthic communities. Filamentous algae, herbivores, and deposit feeders were generally favoured. Facilitation of herbivores strengthened during the growing season, so that the increase in filamentous algae was fully converted to herbivore biomass and charophytes were severely depressed at later successional stages. Exposure and eutrophication levels and sediment type modified the biotic relationships. Two suspension feeder species, the bay barnacle Balanus improvisus and the bay mussel Mytilus trossulus, exerted species-specific impact on the benthic biota. To conclude, the pelagic energy circuit seemed to prevail strongly over the bentho-pelagic coupling in the study area. Nevertheless, the benthic suspension feeding appeared as a significant modifier of benthic communities. Scarce benthic suspension feeders appear capable to release several trophic levels from the prevailing food limitation in low-energy systems, leading to complex direct and indirect community responses.