Foraminifera as indicators of environmental stress: new evidence from the Romanian shelf
Yanko-Hombach, Valentina V.
Likhodedova, O. G.
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The river-dominated shelves of the Black Sea, e.g., the northwestern shelf adjacent to the Danube delta, are characterized by highly dynamic conditions. Their ecosystems are constantly under environmental stress caused by uneven riverine discharge of freshwater enriched with organic and inorganic compounds that provide a local increase in primary productivity and contribute to eutrophication of the water column and export of organic matter to the sea floor. This in turn affects the geochemical processes in bottom sediments and benthic life on both short- (i.e., seasonal) and long-term scales. The main goal of our study is to discover whether there is any correlation between distributional patterns of river input and response to it by the benthic ecosystem (exemplified by foraminifera); the study area is the NW Black Sea shelf adjacent to the Romanian part of the Danube delta. The study consists of two parts: (1) investigation of seasonal (early spring and fall) foraminiferal distribution with regard to environmental parameters, and (2) application of obtained knowledge to the study of sediment cores on both short and long time scales,respectively. In this paper, we present our results on the study of benthic foraminifera in superficial sediments recovered in early spring 2012. Our intent is to demonstrate the interrelation between foraminiferal (e.g., abundance, taxonomic content, and diversity) and environmental parameters that we measured in bottom water (e.g., depth, salinity, transparency, conductivity, T°C, DO, 02, pH, ORP, 615N, C/N) and superficial sediments (Corg, grain size). The aim of this study is to gain insight into whether the benthic ecosystem experiences environmental stress caused by river discharge into the sea.
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