VERTICAL DISTRIBUTION PROFILES OF LIVING (ROSE BENGAL STAINED) BENTHIC FORAMINIFERA FROM EXPERIMENTAL BANKS CONSTRUCTED IN THE VENICE LAGOON

The vertical distribution profiles of living (rose Bengal stained) foraminifera (>150µm) were studied from push cores taken in November, 2006, in the lagoon of Venice, Italy. This study is part of an ongoing project (SIOSED) to determine the effects of annual dredging in the lagoon. Experimental banks were created in order to assess sediment translocation effects on heavy metal behavior and benthic ecologies. Differences were noted in the microhabitat preferences of dominant taxa living within Venice Lagoon sediments. Dominant taxa include: Ammonia parkinsoniana, Ammonia tepida, Haynesina germanica, Aubignyna perlucida, Ammonia spp., Quinqueloculina spp., and Eggerelloides spp. At one site on the experimental banks (V1), all species present are most abundant at the surface (0-1cm); additionally, this site yielded the greatest percentage of aberrant morphologies. At another site, all taxa are abundant deeper within the sediments, and this site yielded the lowest percentage of aberrant morphologies. Comparisons with other sites sampled in the Venice Lagoon revealed differences in the percentages of aberrant morphologies and relative abundances of dominant taxa in different areas of the lagoon. Some species appear to be more prone to develop aberrant morphologies than others. These comparisons showed patterns that may be related to levels of contamination. Examination of foraminiferal microhabitats, sediment characteristics, contamination levels, and aberrant morphologies suggest that some taxa may be influenced by the presence of contaminants. These results provide information that can be used to understand the impacts of heavy metal contamination on benthic foraminiferal ecology within the sediments.