Publikationsdatum:
2012-06-22
Beschreibung:
The evolution of environmental changes during the last decades and the impact on the living biomass in the western part of Amvrakikos Gulf was investigated using abundances of benthic foraminifera and lipid biomarker concentrations. These proxies indicated that the gulf has dramatically changed due to eutrophication. Eutrophication has led to a higher productivity, a higher bacterial biomass, shifts towards opportunistic and tolerant benthic foraminifera species (e.g. B. elongata, N. turgida, T. agglutinans, A. tepida) and a lower benthic species density. Close to the Preveza Straits (connection between the gulf and the Ionian Sea), the benthic assemblages appeared to be less productive and more diversified under more oxygenated conditions. Sea grass meadows largely contributed to the organic matter at this sampling site. Isorenieratane, chlorobactane and lycopane together with oxygen monitoring data indicated that anoxic (and partly euxinic) conditions prevailed seasonally throughout the western part of the gulf with more severe hypoxia towards the east. Increased surface water temperatures have led to a higher stratification, which reduced oxygen resupply to bottom waters. These developments are reasons for mass mortality events and ecosystem decline observed in Amvrakikos Gulf.
Print ISSN:
1810-6277
Digitale ISSN:
1810-6285
Thema:
Biologie
,
Geologie und Paläontologie
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