Macroalgae as indicator species for shore platform zones of Dwarka, Gujarat, India

Abstract

Dwarka coast of Gujarat state in India has a stable shore platform. A study was carried out to identify indicator species among the sampled macroalgae to understand their spatial preferences on the shore platform zones. For this study, the shore platform was divided into three sections in north-south direction: Northern, central, and southern sections. These sections were further divided into three microzones in west-to-east direction based on their local geomorphology and tidal inundation characteristics for more detailed study. These microhabitat zones are: Cliff Base Zone (CBZ), Intertidal Mixed Zone (IMZ) and Subtidal Zone (STZ). To identify indicator species for each microzone, the shore platform was surveyed based on systematic random sampling for two years (April 2013 to April 2015). Line intercept transects and GPS-tagged photo quadrates were carried out from land to seaward as part of the sampling procedure. Indicator species were identified on the basis of a decision-rule when a single species belonged to only one microhabitat zone in all the three sections. Total 97 species of seaweeds were recorded in the shore platform of Dwarka. Out of these, 27 belonged to chlorophyta, 21 to phaeophyta and 49 to rhodophyta. Out of all these species, rhodophyta was found as the dominant group in the shore platform. Out of 97 species, only 12 species were identified as indicator species. Out of these, only one species was from phaeophyta group and eleven from rhodophyta group. This study shows indicator species of the microhabitat zones of the shore platform, with rhodophyta sp. as the prominent macroalgae group. Indicator species can act as proxy indicators of the microhabitats created by the local geomorphology and tidal regime on the shore platform.