Impacts of cultivation of red algae Kappaphycus alvarezii on planktonic and benthic faunal density in relation to environmental and hydrobiological parameters in tropical coastal ecosystem

Abstract

The experimental cultivation of Kappaphycus alvarezii was done to investigate its daily growth rates and biomass yields, and their impacts on planktonic and benthos population densities were evaluated by floating raft culture method. Biomass yields and daily growth rates of K. alvarezii were observed. The phytoplankton and zooplankton densities varied from 25,250 to 319,033 cells/m3 and 12,060 to 207,893 individuals/m3, respectively. Similarly, macrobenthos and meiobenthos densities varied from 11,105 to117061 nos/m2 and 14,740 to 727,000 nos/m2, respectively. The maximum values of plankton and benthos were recorded in the control site compared with the culture sites. Pearson correlation suggests that growth rate of K. alvarezii is negatively correlated with zooplankton density (r = −0.9); macrobenthos (r = −0.9) and meiobenthos density (r = −0.8) at P < 0.01 level. The crop yield negatively correlated with macrobenthos density (r = −0.7) at P < 0.01 level and with meiobenthos density (r = −0.6) at P < 0.05 level for the two culture sites. One- way ANOVA revealed the differences in the growth rates and crop yields. Among the two culture sites, culture site 1 showed significant variation (P < 0.01), whereas culture site 2 showed statistically insignificant (P > 0.01). The conclusion suggests that water nutrient declined at both culture sites than control site. So, the plankton and benthic fauna were declined in the culture sites.