Abstract
The present study deals with seasonal variations, correlation coefficient and biodiversity indices of phytoplankton during April 2011 to March 2012 in the Riwada reservoir, Visakhapatnam, Andhra Pradesh, India. Sampling was performed at five stations during pre-monsoon, monsoon and post monsoon. There were a total of 57 genera belonging to four major groups i.e., Chlorophyceae (27 genera), Bacillariophyceae (14 genera), Cyanophyceae (13 genera) and Euglenophyceae (three genera). Maximum and minimum total phytoplankton population and percentages were recorded at station three in pre monsoon and at station two during monsoon. The maximum and minimum species richness (Menhinick index R2) were found to be 1.29 at station one and 1.10 at station three respectively. Maximum and minimum species diversity (H1) were found at station four (3.98) and station two (3.71). Maximum species evenness was recorded at stations one, being four and five; minimum species evenness was recorded at station two. Correlation coefficient matrix indicated significant positive relationship with water temperature, pH, transparency, biological oxygen demand and chlorides, negative relationship with electric conductivity, total solids, total dissolved solids, total hardness, dissolved oxygen, nitrates, sulphates and phosphates of water. The diversity indices showed that the reservoir have a well balanced phytoplankton community.
Highlights
Phytoplanktons are important in an environmental impact study in as much as they are extremely responsive to change in the environment and indicate environmental changes and fluctuations that may occur (Ingole et al, 2010)
Phytoplanktons play an important role in the biosynthesis of organic matter in aquatic ecosystems, which directly or indirectly serve all the organisms of a water body as food (Anjana et al, 1998)
The phytoplanktons settled were diluted to a desirable concentration in such a way that they could be counted individually under compound binocular microscope and phytoplanktons were measured and multiplied with the dilution factors, using Sedgwick Rafter cell
Summary
Phytoplanktons are important in an environmental impact study in as much as they are extremely responsive to change in the environment and indicate environmental changes and fluctuations that may occur (Ingole et al, 2010). They have a short life span and responds quickly to environmental changes (Zębek, 2004). Several researchers Leela et al (2010), Nafeesa et al (2011a) and Shanker (2010) have studied and opined that limnological characteristics of any waterbody alter the phytoplankton diversity. Hosamani and Bharathi (1980) studied the use of phytoplankton in classifying water bodies and found it as significant
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