Effects of different culture periods of commercial invasive red alga Kappaphycus alvarezii (Doty) Doty on plankton community structures in tropical marine environment, Southeast coast of India

Abstract

The commercial invasive red alga Kappaphycus alvarezii was cultivated by floating raft technique for the assessment of crop yields, growth rates and their impacts on the plankton community related to hydrobiological parameters in the Munakadu coast, Southeastern India for the period of one year from February 2016 to January 2017. The ANOVA results showed that the crop yield and daily growth rate of K. alvarezii was significantly higher (p < 0.05) during the monsoon season. In the control site, a positive correlation was found between pH with NO3 and Chlorophyll-a (Chl-a) at p < 0.01 level and pH with gross primary productivity at p < 0.05 level. Gross primary productivity (GPP) was positively correlated with net primary productivity (NPP) at p < 0.01 levels. In the culture site, significant positive correlation was found between salinity and PPD; pH and GPP; DO and BOD; NO3 and C. yield; GPP and NPP. In total, 43 and 37 phytoplankton species were recorded in the control site and culture site, respectively. The overall species diversity (H’), richness (D’) and evenness (J’) of phytoplankton were higher in the control site than the culture site. Therefore, the population density of the control site seems to be higher than the culture site. The copepods and meroplankton were dominant groups that present in the highest percentages during the entire study period in the culture site. The present study suggests that copepods and meroplankton were always higher in K. alvarezii farming sites and other species were higher in the control site. The higher percentage of diatoms, cyanobacteria and the lower percentage of dinoflagellates were present in the culture sites. Evidently, the farming of K. alvarezii significantly affected the plankton population concerning different seasons in the tropical marine environment of Munaikadu coast, Southeast coast of India.