Styela plicata: a new promising bioindicator of heavy metal pollution for eastern Aegean Sea coastal waters

As part of a research project, the concentrations of Cd, Cu, Pb, V, and Zn in the tissues of Styela plicata were investigated for the first time to determine if S. plicata is a suitable biological indicator for biomonitoring of heavy metals in eastern Aegean Sea coastal waters. To examine the relationships, heavy metal levels in suspended particulate matters (SPMs) and sediments were also determined. According to the results, the mean metal levels in SPM, sediments, and S. plicata samples could be arranged in the following order of abundance: Zn > Cu > Pb > V > Cd. As for heavy metal levels, significant positive correlations were noted between Cd-Pb, Cd-V, Cd-Zn, Cu-V, and Pb-V in SPM; Cd-Zn, Cu-Zn, Pb-Cd, Pb-Cu, and Pb-Zn in sediment; and Cu-Pb, Cu-Zn, and Pb-Zn in S. plicata samples. Positive relationships between these metals showed that they were originated from same sources and that they were associated with each other. Based on the findings, Zn, Cu, and Pb concentrations in suspended particulate matters, sediments, and S. plicata samples were generally represented with higher levels at stations that were used for boating, shipping, and related activities. As S. plicata is a strongest accumulator of V, the relatively low V levels observed in this study may indicate the lack of anthropogenic sources of this metal in the sampling stations. In conclusion, suspended particulate matter and sediment can be useful tool to detect the pollution status of the marine environment. Furthermore, the findings of this study highlighted that S. plicata is a promising alternative for the monitoring of heavy metal pollution for eastern Aegean Sea coasts.