Determination of numerical scale of water quality based on the algal bloom potential in the southern Caspian Sea-Goharbaran (Mazandaran Provience)

A growing human population and increased demand for protein will made marine aquaculture inevitable. Water quality monitoring is important due to the great interactions between water quality and aquaculture activities. Therefore, the present study was performed because of the importance of the phytoplankton studies in the environmental and monitoring studies in order to scale water quality based on the algal bloom potential in the southern Caspian Sea-Goharbaran where can be used for cage and pen fish farming. Water samples were collected monthly from different layers of water (surface, 5 and 10 m) at various depths (5, 10 and 15 m) during 2013-2014. Based on the results, the algal bloom threshold for phytoplankton abundance, phytoplankton biomass and chlorophyll-a concentration were 200 million cells/m3, 512 mg/m3 and 1.7 µg/L, respectively. The abundance of Binuclearia lauterbornii, Thalassionema nitzschioides and Pseudonitzschia seriata were in the medium class of algal bloom in the summer, autumn and winter, respectively. The scaling of water quality based on the algal bloom were defined as excellent from April to June, fine-medium in September and in October and medium-weak from January to early March. In the present study, using various parameters of phytoplankton (abundance, biomass and chlorophyll-a concentration) and evaluating biological and ecological characteristics of dominant phytoplankton species were increased the validity of the numerical scalling of water quality.