Inter-annual and seasonal variations in hydrological parameters and its implications on chlorophyll a distribution along the southwest coast of Bay of Bengal

Abstract

Seasonal and inter-annual variability of hydrological parameters and its impact on chlorophyll distribution was studied from January 2009 to December 2011 at four coastal stations along the southwest Bay of Bengal. Statistical analysis (principal component analysis (PCA), two-way analysis of variance (ANOVA) and correlation analysis) showed the significant impact of hydrological parameters on chlorophyll distribution in the study area. The ranges of different parameters recorded were 23.8-33.8°C (SST), 4.00-36.00 (salinity), 7.0-9.2 (pH), 4.41-8.32 mg/L (dissolved oxygen), 0.04-2.45 μmol/L (nitrite), 0.33-16.10 μmol/L (nitrate), 0.02-2.51 μmol/L (ammonia), 0.04-3.32 μmol/L (inorganic phosphate), 10.09-85.28 μmol/L (reactive silicate) and 0.04-13.8 μg/L (chlorophyll). PCA analysis carried out for different seasons found variations in the relationship between physico-chemical parameters and chlorophyll in which nitrate and chlorophyll were positively loaded at PC1 (principal component 1) during spring inter-monsoon and at PC2 (principal component 2) during other seasons. Likewise correlation analysis also showed significant positive relationship between chlorophyll and nutrients especially with nitrate (r=0.734). Distribution of hydrobiological parameters between stations and distances was significantly varying as evidenced from the ANOVA results. The study found that the spatial and temporal distribution of chlorophyll was highly dependent on the availability of nutrients especially, nitrate in the southwest Bay of Bengal coastal waters.

Influence of physico-chemical parameters and pCO2 concentration on mangroves-associated polychaetes at Pichavaram, southeast coast of India

“…The high concentration of chlorophyll 'a' recorded during monsoon season might be due to land runoff from the rivers, causing low salinity, higher turbidity and less availability of light as stated by Kumar et al [54]. Earlier reports also indicated that freshwater discharges from the rivers during monsoon season led to higher concentration of chlorophyll 'a' [54][55][56], and thus, the range of chlorophyll recorded presently is justifiable.…”

Monitoring of monthly scale chlorophyll concentration variability in the Bay of Bengal and Arabian Sea using MODIS Aqua Satellite Data

“…In addition, BoB has lower nutrient concentrations and less cyclonic events were documented than AS. (Sarangi, 2015;Shanthi et al, 2015. However, in evaluation with previous reported studies the chlorophyll concentration ranges from 0.4 -1.0 mg m -3 was observed in Arabian Sea using satellite data reported by Chauhan et al, 2001;Dey & Singh, 2003;Sarangi et al, 2001;2005 3) because more number of cyclonic events were documented during April -December, 2008 in North Indian Ocean however end of cyclones passages leads to enhanced more nutrients level in that region is answerable for highest chlorophyll concentration was obtained for the year 2008 compared with 2007 and previous studies also.…”