Comprehensive Assessment of Long-Term Changes of the Black Sea Surface Waters Quality in the Zmiinyi Island Area

On the basis of chlorophyll "a", dissolved oxygen, total nitrogen and total phosphorus concentrations measurements values of the Trophic index TRIX for 2004-2010 in the Zmiinyi Island area in the Black Sea were calculated. Inter-annual dynamics of the Trophic index TRIX is analysed. It has been shown that TRIX index in the Zmiinyi Island area varied in wide range between 3.1 and 6.9 that corresponded to the trophicity categories from low to very high. Results of TRIX seasonal dynamics analysis showed that minimal monthly average values were most often found during winter and summer period and maximal in spring and autumn and were connected with intensity of river discharge. Modelling of TRIX for 1988-2003 is presented. Comparison with the results of other Black Sea researchers has shown that sea water quality near the Zmiinyi Island is much higher than in the other coastal areas of the Black Sea. It has been proposed to use the marine research station "Zmiinyi Island" as a background one for estimation of quality of marine waters in the western part of the Black Sea.