Abstract
There are several toxic microalgae species known as Harmful algal bloom (HAB) causing serious effects to the environment and economy. Knowledge on these groups of marine micro-flora is scanty and several areas remain unexplored. The present study focuses on the analysis of microalgal diversity in the Malabar coastal areas at Southwest and Northeast monsoon. The diatoms, dinoflagellates and total microalgal population were analysed and quantified. Predominant species were identified. Physicochemical parameters of the seawater at different time intervals and Correlation between diatoms, dinoflagellates and total microalgae population with physicochemical parameters were identified. From the analysis, a total of 53 diatoms and 15 dinoflagellates were identified. The predominant species including toxic or harmful bloom-forming were found to be Dinophysis caudata, Noctiluca scintillans, Prorocentrum lima and Tripos furca. The total microalgae population varied from 18,592 cells/L to 7,832 cells/L in the months of April and December. Dinoflagellates were positively correlated with salinity (r = 0.848; p = 0.008), nitrite (r = 0.752; p = 0.032) and total phosphorous (r = 0.734, p = 0.038). Diatoms were positively correlated with temperature (r = 0.804; p = 0.016) and nitrate (r = 0.774, p = 0.024). Total microalgal density was positively correlated with temperature (r = 0.825; p = 0.012) and nitrate content (r = 0.811, p = 0.15).
Highlights
Life in the sea consists of three major groups of organisms namely plankton, nekton and benthos, and among these, the plankton is of fundamental importance to fisheries and the environment.1 Microalgae, the predominant primary producers are restricted to the neritic zone due to the abundance of nutrients, light and favourable physicochemical variables like temperature, pH and salinity.2,3Microalgae constitute 40-50% primary production that occurs by all the algal photosynthesis4 and the secondary production and tertiary production depend on it
The present study focuses on the analysis of microalgal diversity in the Malabar coastal areas at Southwest and Northeast monsoon
A total of 53 diatom species were collected and identified during the study period belonging to different families like Coscinodiscaceae, Actinodiscaceae, Eupodiscaceae, Rhizosoleniaceae, Chaetoceraceae, Biddulphiaceae, Euodieae, Hemiauliniae, Fragilarioidaceae, Achnanthoidaceae and Naviculoidaceae (Table 1)
Summary
Life in the sea consists of three major groups of organisms namely plankton, nekton and benthos, and among these, the plankton is of fundamental importance to fisheries and the environment. Microalgae, the predominant primary producers are restricted to the neritic zone due to the abundance of nutrients, light and favourable physicochemical variables like temperature, pH and salinity.. Harmful Algal Blooms can have wide socio-economic and health impacts Every year, they cause billions of dollars loss through damaging fishes and sea products.. The microalgae analysis for algal bloom study. The details about the sampling are as follows: Qualitative microalgae analysis. The phytoplankton were collected for the qualitative analysis from the site of sampling using a standard phytoplankton collection net with a mesh size of 20 μm, a mouth diameter of 50 cm and a length of 1 m. After the collection, the live sample was analysed for the identification of toxic microalgal species. The sampling for quantitative microalgae analysis was done by filtering 100 litres of sea. For the analysis of different physicochemical parameters, the samples were collected from the study site, 2 km away from the shore. All tests are double-tailed and P-value of less than 0.05 was considered statistically significant
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