SEASONAL ASSESSMENT OF HYDROGRAPHIC VARIABLES AND PHYTOPLANKTON COMMUNITY IN THE ARABIAN SEA WATERS OF KERALA, SOUTHWEST COAST OF INDIA

The seasonal variation of the hydrographic variables and phytoplankton species in the Arabian Sea waters of the Kerala coast, Southern India was investigated during different seasons. The variables such as pH, temperature, salinity, turbidity and chlorophyll-a contents of water were found to be high during pre-monsoon season and the dissolved oxygen content was minimal. The concentration of nutrients viz., nitrate, phosphate, silicate varied independently. In the study a total of 53 species of phytoplankton were recorded. Their density was higher during the post-monsoon season than during other seasons and the diatoms were found to be the dominant species. The major phytoplankton in terms of frequency and abundance were the species namely, Biddulphia mobiliensis, Chaetoceros curvisetus, Licmophora abbreviata, Skeletonema costatum, Prorocentrum micans and Oscillatoria sp. They showed significant positive correlation with pH, temperature, salinity, nitrate, phosphate and chlorophyll-a contents, whereas turbidity, dissolved oxygen and silicate exhibited significant negative correlation. The Principal Component Analysis (PCA) developed two principal components with 84.74% of total variability in the water quality which separated pre- and post-monsoon periods from the monsoon season on axis I, and pre-monsoon and monsoon periods from post-monsoon on axis II.Foi investigada a variação sazonal das variáveis hidrográficas e das espécies de fitoplâncton nas águas do Mar Arábico da costa de Kerala, sul da India, em diferentes estações do ano. Variáveis como pH, temperatura, salinidade, turbidez e conteúdo de clorofila-a das águas mostraram-se altas durante a estação pré-monção enquanto o conteúdo de oxigênio dissolvido foi mínimo. A concentração de nutrientes, tais como nitrato, fosfato e silicato, variaram independentemente da época. Foi encontrado um total de 53 espécies, com picos de densidade durante a estação pós-monção, sendo a dominância exercida pelas diatomáceas. Em termos de frequência e abundância, as espécies mais importantes foram Biddulphia mobiliensis, Chaetoceros curvisetus, Licmophora abbreviata, Skeletonema costatum, Prorocentrum micans and Oscillatoria sp. Estas apresentaram correlação significativa positiva com pH, temperatura, salinidade, nitrato, fosfato e conteúdo de clorofila-a, enquanto que com turbidez, oxigênio dissolvido e silicato exibiram correlação negativa. A Análise de Componentes Principais (ACP) mostrou que os dois primeiros eixos contêm 84,74% da variação na qualidade das águas. O eixo I separou os períodos de pré- e pós-monção do período de monção, enquanto o eixo II separou os períodos de pré-monção e monção do período de pós-monção

SEASONAL ASSESSMENT OF HYDROGRAPHIC VARIABLES AND PHYTOPLANKTON COMMUNITY IN THE ARABIAN SEA WATERS OF KERALA, SOUTHWEST COAST OF INDIA

The seasonal variation of the hydrographic variables and phytoplankton species in the Arabian Sea waters of the Kerala coast, Southern India was investigated during different seasons. The variables such as pH, temperature, salinity, turbidity and chlorophyll-a contents of water were found to be high during pre-monsoon season and the dissolved oxygen content was minimal. The concentration of nutrients viz., nitrate, phosphate, silicate varied independently. In the study a total of 53 species of phytoplankton were recorded. Their density was higher during the post-monsoon season than during other seasons and the diatoms were found to be the dominant species. The major phytoplankton in terms of frequency and abundance were the species namely, Biddulphia mobiliensis, Chaetoceros curvisetus, Licmophora abbreviata, Skeletonema costatum, Prorocentrum micans and Oscillatoria sp. They showed significant positive correlation with pH, temperature, salinity, nitrate, phosphate and chlorophyll-a contents, whereas turbidity, dissolved oxygen and silicate exhibited significant negative correlation. The Principal Component Analysis (PCA) developed two principal components with 84.74% of total variability in the water quality which separated pre- and post-monsoon periods from the monsoon season on axis I, and pre-monsoon and monsoon periods from post-monsoon on axis II

Biochemical composition of seven species of cyanobacteria isolated from different aquatic habitats of Western Ghats, Southern India

The aim of this work was to study the biochemical constituents of seven species of cyanobacteria namely, Calothrix fusca, Gloeocapsa livida, Lyngbya limnetica and Scytonema bohneri isolated from Panekal sulfur spring. The species namely, Oscillatoria acuminata from petrochemical refinery, O. calcuttensis from dairy effluent and O. foreaui from a sewage drain located in the Western Ghats of Southern India under laboratory culture conditions. The biochemical constituents were analyzed in terms of total carbohydrates, total protein, total free amino acid, total lipid, fatty acid and mineral contents. The analysis showed that maximum amount of total carbohydrate in S. bohneri (28.4% dry weight) and minimum in O. foreaui (8.0% of dry weight). Maximum amount of total protein and total free amino acid were in O. foreaui (7% of dry weight). O. calcuttensis showed higher amount of total lipid (20% dry weight). A total of 12 types of fatty acids were detected among which lauric acid was in highest quantity in all the seven species. Among the polyunsaturated fatty acids, oleic acid was present in all the species ranging from 1.68 to 3.89%. O. foreaui showed highest quantities of copper, manganese, ferrous and zinc. Nickel was maximum in S. bohneri (11.05 µgmL-1). O. acuminata showed highest quantity of magnesium (21.050 mg g-1) and it was least in O. foreaui (12.812 mg g-1)