CORRELATION PROFILES OF THE ACCUMULATED METALS IN SEAWATER, SEDIMENT AND Pachygrapsus marmoratus (Fabricius) TISSUES IN BLACK SEA (ORDU, TURKEY)

Abstract

This study was performed in order to investigate the interactions of accumulation patterns of some metals (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in exoskeleton, gill, hepatopancreas and muscle tissues of the marbled crab Pachygrapsus marmoratus (Fabricius) sampled from near streams and domestic discharge points along the coastal region of Black Sea along Ordu in Turkey as well as patterns in sediment and seawater samples of the crab sampling sites. The study area covering a coastal stretch of 28 km along Black Sea lies between the latitudes 41°03'46.42"-41°07'42.35"N and longitudes 37°28'45.63"-37°41'15.29"E. The metal contents of the samples were analysed by the inductively coupled plasma - optical emission spectrometry (ICP-OES) technique. The results showed that the accumulation orders of the metals, in a descending order, were Fe>Al>Mn>Zn>Cr>Pb>Cu>As>Ni>Cd in the sediment, Fe>Mn>Cr>As>Cd in the water, and Al>Fe>Cu>Mn>Zn in crab tissues when evaluated together. In the crab samples, the amount of the accumulation of all metals was ordered as gills>exoskeleton>hepatopancreas>muscle. Al and Fe were the predominant metals in the sediment and crab tissues but Al was not detected in the seawater samples. A correlation test was performed to reveal the interaction of accumulation in the sediment, water and crab tissues. Metal-metal interactions and their co-accumulation was detected by correlation test. These interactions which exist in the crab tissues but not in the seawater and sediment were the main point of this study. Gills and exoskeleton displayed the greatest number of significant correlations between metal–metal interactions. Also, metal concentrations were found to be higher in the gills and exoskeleton. Strong correlations between Mn-Al (r=0.954, correlation p<0.001), in the exoskeleton, Al-Fe (r=0.849, correlation p<0.001), Mn-Zn (r=0.854, correlation p<0.001) in the gills, Al-Zn (r=0.882 correlation p<0.001) in the hepatopancreas were determined. Moderate correlations between Zn-Cu were found in the hepatopancreas. These metal-metal interactions may have been a result of metallothionein activity. No significant relations were found between metal levels in sediment samples and crap tissues (p>0.05). The results also showed that metals present in the seawater and sediment did not directly transform to tissue accumulation. This result showed that metal amounts in the tissues of the P. marmoratus did not reflect environmental contaminations and that sediment accumulated higher amounts of metals than seawater and tissues.