Post decomposition effect of water hyacinth on marine phytoplankton - A laboratory study

Abstract

Solutions obtained from post decomposition of different parts of water hyacinth were diluted with filtered seawater into different concentration (10%, 40%, and 60%) and used for the culture of Skeletonema costatum and Thalassiosira subtilis. The solutions significantly affected the biomass growth of S. costatum and T. subtilis. Highest growth of S. costatum was recorded in leaf decomposed solution followed by petiole decomposed solution. High biomass growth of T. subtilis was recorded in the culture containing solution obtained from decomposed root. The diluted solution (40%) obtained from decomposed leaf significantly affected S. costatum growth (39.3 mg.l-1) after 3 days, while the diluted solution (10%) of decomposed root showed significant growth of T. subtilis (8.5 mg.l-1) after 5 days. High biomass growth of the culture might be due to high nutrients, such as nitrogen, phosphate and silicate content in the solution. Considering the bloom forming nature of this phytoplankton species and its ability to take advantage of transient nutrient flux, the study indicated a high probability of bloom occurring post macrophyte decomposition