Fouling diatoms of Andaman waters and their inhibition by spinal extracts of the sea urchin Diadema setosum (Leske, 1778)

Abstract

Diatoms play a central role in biofouling by attracting microscopic reproductive propagules of macroorganisms. This study reports on the seasonal variation of fouling diatoms in waters of the South Andaman Sea and evaluation of their inhibition by spinal extracts of the sea urchin Diadema setosum on glass slides. Pennate diatoms were more abundant than centric diatoms in the fouling film. The genera Navicula and Amphora were dominant throughout the study. Apart from that, an abundance of the genera Cocconeis and Thalassiosira was observed during the pre-monsoon period; Nitzschia was abundant during the monsoon period and Achnanthes and Thalassiosira during the post-monsoon period. Two separate fractions were extracted from the spines using ethanol and distilled water as solvents. The ethanol extract fraction showed inhibition against eight major fouling diatoms. The ethanol extract exhibited a higher inhibitory effect than the aqueous extract against biofilm formation, confirming that the organic fraction has microfouling inhibitory compounds.