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RESEARCH PRODUCT

First assessment of total organic carbon/macrofauna relation in Sicilian coastal lagoons

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Sediment characteristics (Total organic carbon, C/N ratio, carbonates, grain size) and macrofaunal assemblages were studied in Sum- mer 2005 in 9 coastal lagoons of eastern Sicily (Italy) belonging to 3 study areas (Capo Peloro, Marinello and Vendicari). The diffe- rent ecosystems were selected upon their differences in geographical position, size, depth, water exchange, anthropic impact and expec- ted organic matter loading. The aim of this study was to explore the relationship between the Total organic carbon (TOC) content of se- diment and macrofaunal assemblages characteristics, as indicated by the Study Group on Benthic Indicators of IOC/UNESCO (http: //ioc.unesco.org/benthicindicators/). A total of 30813 specimens belonging to 51 families were collected and identified. Abun- dance (N), Family richness (F), Shannon (H') and Evenness (J') indexes were compared with sediment characteristics. Bioenv analysis and Pearson correlations have shown that grain size represents an important variable influencing the macrofaunal settlement. TOC ranged between 2 and 75 mg g -1. Coherently with previous studies on this topic, our results suggest that risk of reduced abundance and biodiversity due to organic loading in sediments of Sicilian coastal lagoons is low at TOC concentrations less than about 10 mg g -1, high at TOC concentrations greater than about 30 mg g-1 and intermediate at concentrations in between.