Phytoplankton and nutrient dynamics of shallow coastal stations at Bay of Bengal, eastern Indian coast
In: Aquatic Ecology. Springer: Dordrecht; London; Boston. ISSN 1386-2588; e-ISSN 1573-5125, more
|   |
| Keywords |
Aquatic communities > Plankton > Phytoplankton
Biodiversity
Nutrients (mineral)
Periodicity > Seasonality
ISW, Bengal Bay [Marine Regions]; ISW, India [Marine Regions]
|
| Author keywords |
Phytoplankton diversity; Nutrients; Seasonality; Principal componentanalysis (PCA); Multi dimensional scaling (MDS) |
| Abstract |
Phytoplankton dynamics of Eastern Indian coast was studied from surface water for a period of 24 months (April 2005–March 2007) in relation to environmental variables like, temperature, pH, dissolved oxygen, biochemical oxygen demand (BOD), salinity and nutrient contents—including nitrate, phosphate and silicate. Total 43 taxa were recorded during the study period. Phytoplankton density ranged from approximately 350–3,000 cells/ml and showed complete dominance of diatom genera namely, Asterionella japonica in winter and Odontella rhombus in summer. Other frequently occurring diatoms were Coscinodiscus perforatus, Actinocyclus normanii f. subsala, Thalassiothrix fraunfeldii, Ditylum brightwelli, Stephanodiscus hantzschoides, Cyclotella meneghiniana, Thalassionema nitzschoides etc. Seasonal changes in abundance and diversity of phytoplankton significantly differed showing maximum diversity in autumn with high diversity index (2.76-Oct, 05) and minimum in winter (0.326-January, 06). The species evenness varied from 0.137 (January 06) to 0.991 (August 06), which signifies minimum variation in percentage contribution of individual species to total phytoplankton population in monsoon and maximum in winter. Correlation studies of total cell count to physicochemical variables indicated significant positive relation with dissolved oxygen, salinity and pH but negative relation with nitrate, silicate and BOD of the water body. Multivariate procedures like ordination by principal component analysis and multi dimensional scaling of phytoplankton population based on their occurrence data and magnitude of abundance indicated that some genera (Biddulphia heteroceros, B. dubia, Odontella aurita, Gyrosigma acuminatum, Coscinodiscus granii, Paralia sulcata, etc.) have specific preference for water temperature and salinity and flourished maximally in particular season(s). While other genera (A. japonica, C. meneghiniana, C. perforatus, D. brightwelli, S. hantzschoides, etc.) appeared in wide range of temperature and salinity gradient. |
|
