Effect of alcohol extracts of demospongiae on growth of periphytic diatoms

Abstract

<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Antifouling potentialities of alcohol extracts of demospongiae, collected of east coast of India, against four dominant marine fouling diatoms are reported. Of the 20 combinations worked out (5 sponges × 4 diatoms) 16 interactions showed activity accounting to about 80%. <i>Plakortis simplex, Azorica pfeifferae </i>and <i>Decitopsis </i>sp. showed 100% growth inhibition against all the 4 fouling diatoms <i>(Navicula sbinflata, Navicula crucicula, Nitzschia </i>sp., <i>Amphora </i>sp.) tested, imp lying the presence of potent antifouling compounds whilst, other extracts showed species specificity in their action. However, the same cells exhibited normal growth , when transferred to extract free media, pointing towards non toxic way of action . The EC₅₀ values varied with extracts and test organisms used and ranged from 14 mg/ml (<i>A. pfeifferae vs N. Crucicula</i>) to <span style="font-size:14.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;color:black;mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">583 μ<span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">g/ml <i>(Dercitopsis </i>sp. <i>vs Amphora </i>sp.). The active extracts totally arrested the silicate uptake on diatoms, treated with EC₁₀₀ values, in relation to control. The degree of silicate uptake impairment varied with extracts and test organisms used. The results imply the possible potentialities of these extracts in controlling the microfoulers.</span></span></span>