Impact of discharge of soda ash industry effluent on abundance and community structure of rocky intertidal macroalgae of the Arabian Sea, Gujarat, India

Impact of soda ash industry effluent on macroalgal distribution, abundance, species composition, diversity and standing stock was studied, in situ, on tropical seaweeds of Arabian Sea, Gujarat. Comparatively, less number of species and different pattern of macroalgal assemblages were recorded at the discharge point, while transects distance from discharge point showed more number of species, luxuriant growth and well developed macroalgae. Factors responsible for structuring macroalgal communities were distance from the effluent discharge point, degree of tidal flushing and tolerance capacity of the macroalgae to the effluent. Caulerpa sertulariodes and Champia somalensis were most resistant and had a preference for soda ash industry effluent as they were recorded only near the effluent discharge point. Codium dwarkense and Dictyota bartayresiana also had similar characteristics as they were recorded only 1 km away from the effluent discharge point. Caulerpa racemosa, Chamaedoris auriculata, Valoniopsis pachynem and Stoechosperumum marginatum were most sensitive as they were recorded only from the control site. Ulva lactuca, Caulerpa taxifolia, Gracilaria corticata and Laurencia cruciata were recorded from all sampling sites indicating their adaptability to varying degrees of pollution.