Investigation on recent benthic foraminifers used as bioindicators for monitoring coastal pollution revealed that phototrophic bacterial colonies infest the surfaces of the calcareous benthic foraminifers. Many traces of microborers have been observed in foraminiferal shells coming from shallow waters in an industriai polluted coast. Samples were collected in the end of July 2006. Sampling depths ranged from the intertidal to two meters; water temperature were about 27°C to 31°C and salinity values of about 37 g/I. Preliminary results from SEM pictures have allowed to recognize the following ichnotaxa: Fasciculus acinosus Glaub related to the modern cyanobacterial species Hyella balani Lehmann, Orthogonun sp., which biological identity of its producers is unknown, and Scolecia filosa Radtke related to modern cyanobacterium Plectonema terebrans Bornet & Flahanet. Geochemical analysis performed on sediments show that the investigated industriai area is contaminated mainly by heavy metals (Fe, Mn, Pb, Zn, Cd). Increasing pollution results in low species diversity and population density, associated with an increase in tolerant or opportunistic species. In this contaminated environment aberrant foraminiferal tests were frequently found. Microanalysis reveals that deformed specimens locally contain high level of heavy metals. This suggests that heavy metals pollution may represent a particular microenvironment able for developing microbial communities. In fact the unpolluted coastal areas near the studied sites at the same batimetry don't show bioerosion traces; higher species diversity and population density than polluted areas and very scarce deformed forms were found.
Microbioerosion on the shells of recent foraminifers in polluted shallow water environment
DA PELO, STEFANIA;IBBA, ANGELO
2007-01-01
Abstract
Investigation on recent benthic foraminifers used as bioindicators for monitoring coastal pollution revealed that phototrophic bacterial colonies infest the surfaces of the calcareous benthic foraminifers. Many traces of microborers have been observed in foraminiferal shells coming from shallow waters in an industriai polluted coast. Samples were collected in the end of July 2006. Sampling depths ranged from the intertidal to two meters; water temperature were about 27°C to 31°C and salinity values of about 37 g/I. Preliminary results from SEM pictures have allowed to recognize the following ichnotaxa: Fasciculus acinosus Glaub related to the modern cyanobacterial species Hyella balani Lehmann, Orthogonun sp., which biological identity of its producers is unknown, and Scolecia filosa Radtke related to modern cyanobacterium Plectonema terebrans Bornet & Flahanet. Geochemical analysis performed on sediments show that the investigated industriai area is contaminated mainly by heavy metals (Fe, Mn, Pb, Zn, Cd). Increasing pollution results in low species diversity and population density, associated with an increase in tolerant or opportunistic species. In this contaminated environment aberrant foraminiferal tests were frequently found. Microanalysis reveals that deformed specimens locally contain high level of heavy metals. This suggests that heavy metals pollution may represent a particular microenvironment able for developing microbial communities. In fact the unpolluted coastal areas near the studied sites at the same batimetry don't show bioerosion traces; higher species diversity and population density than polluted areas and very scarce deformed forms were found.
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