engleski

Environmental Conditions Reflected on Shells Mytilus galloprovincialis from Eastern Coastal Area of Adriatic Sea

In order to estimate the influence of environmental conditions on the excretion of resistant part of the organism samples of recent M. galloprovincialis were taken from entire eastern coastal area of Adriatic Sea from polluted and reference unpolluted locations in October 1998. Isotopic composition and metal concentrations in shells were measured. M. galloprovincialis deposits daily accretionary growth bands in the outer prismatic calcite layer of its shell, which contains a continuous record of seawater temperature and chemical conditions. Since aragonite shell layer is found to be enriched in 18O and 13C relative to coexisting calcite shell layer at relevant temperatures, the shell layers were sampled separately for isotopic analysis. On average, aragonite was enriched by 1, 07 ‰ in 13C and by 0, 15 ‰ in 18O. The 18O / 16O ratio of carbonate reflects the δ 18O of water from which it was deposited and the temperature at which the deposition occured. The calculated temperatures of the seawater were between 17, 7 - 24, 7°C for calcite and from 20, 5 - 28, 3°C for aragonite, which coincide with measured temperatures on investigated locations. According to our results of δ 18O and δ 13C in shell layers of M. galloprovincialis, the locations of the investigated area could be separated into three groups: those with more influence of fresh water, those with less influence of fresh water and those of marine environments. Results of isotopic composition of carbon indicate that shells from locations influenced by fresh water inflow are depleted with 13C. The highest contents of Mn, Ba, B, As, Ni in the shells of M. galloprovincialis were found in locations, where chemical and heavy industry is located and close to the sewage outlets. The highest concentrations of manganese were determined in the samples from mouth of the Neretva River, which is contaminated by industrial sewage. The highest concentrations of zinc, lead, copper were measured in samples collected close to bigger ports. The shell of M. galloprovincialis has proven to be a good indicator of pollution and environmental conditions of Adriatic coastal area. Palaeoenvironmental conditions of the habitat were detected. Therefore, carbonate shells can be considered as very important palaeoenvironmental indicators.

Stable isotopes; Mussels; Adriatic Sea; Heavy metals; Biomonitoring

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