Seasonal variation in the diversity of Holoplankton and Meroplankton in relation with primary productivity and physicochemical parameters in the nearshore regions of the Visakhapatnam Coast, India

The nearshore region of a coastal ecosystem is an everchanging, dynamic, transitional zone between land and open sea. It is a highly productive area because of sufficient sunlight and nutrients. The main aim of this research is to study the diversity and abundance of zooplankton especially holoplankton and meroplankton in relation with physicochemical factors for one year with their seasonality. Along with the diversity indices, multivariate ordination indices like Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA) were applied to study the diversity and their relationship with physicochemical factors. PERMANOVA was also used to test whether the abundance and physicochemical factors differed significantly across sampling sites and seasons. The study showed that holoplankton diversity in the Fishing Harbour (FH) was highest during the pre-monsoon season and lowest during the post-monsoon season. The meroplankton diversity was the highest during the pre-monsoon season and lowest during the monsoon season which was also recorded from the FH. Principal Component Analysis (PCA) showed that Salinity, pH, dissolved oxygen and primary productivity as the significant physicochemical parameters affecting the Holoplankton and Meroplankton diversity. Canonical Correspondence Analysis (CCA) for holoplankton showed that salinity, pH, dissolved oxygen and primary productivity were positively related with copepods. While non-copepod species were positively related with salinity, pH and dissolved oxygen except primary productivity. Similarly, meroplankton groups showed positive correlation with temperature only.