Assessment of various oceanographic parameters and inter comparison of primary production estimates around Chennai coast - Tamil Nadu, India

In this research work, the primary production along the Bay of Bengal is estimated from the field data collected from 21 stations, between 2013 and 2015 from different algorithms and compared with primary production determined experimentally in laboratory. Other important oceanographic parameters such as chlorophyll a, nutrients, suspended matter, dissolved oxygen and salinity are also evaluated in the water samples. The study resulted with observed primary production values of 339.94 g C m2 yr−1or 225.16 g C m3 yr−1 by averaging five different algorithms. Using the relationship between primary production and fish production, the common fish catch predicted inside the study vicinity is estimated with the aid of Eppley et al. technique (1985) as 87.29 ± 47.90 kg/ ha. The total yearly fish production for the estuarine, coastal and offshore regions was calculated using empirical relations as 14549 tons. In light of the determined primary production values the fish biomass was assessed by writing conditions given in literatures and the fish standing biomass estimated for the study stretch is 0.15 tons/km2 for the Bay of Bengal region. From the Chlorophyll a measurements, about 76% of the sampling locations are categorized in to ultra-oligotrophic state (average chlorophyll a values ≤1 mg/m3), 14% of the sampling stations are grouped in to oligotrophic state (average chlorophyll a values ≥1 and ≤2.5 mg/m3) and 5% of the locations are classified in to mesotrophic state (average chlorophyll a values ≥2.5 and ≤8 mg/m3) and eutrophic state (≥8 and ≤25 mg/m3).