Loss of Dugong grass [Halophila ovalis (R. Brown)] population structure due to habitat disturbance in an island ecosystem

Abstract

Seagrass ecosystems are lost due to habitat disturbance, coastal development, and human activities. The impact of boat anchors from traditional fishing and recreational activities was assessed on the seagrass Halophila ovalis from the Andaman and Nicobar Islands (ANI) of India. The plant density, biomass, morphometrics, canopy height and percentage cover were estimated from two sites of Govind Nagar beach of ANI. The shoot density of H. ovalis was reduced by physical damage caused by boat anchors. The morphometrics of H. ovalis, such as the number of leaves per ramet, leaf length, width, and horizontal rhizome length was significantly reduced when impacted by boat anchors. Seagrass canopy height and percentage cover were reduced by 71 and 54 %, respectively. Though the impact of boat anchors reported here is on a small-scale, it may impact the feeding grounds of locally endangered dugongs. Therefore, proper management and preventive measures should be implemented to prevent the loss of dugong grass habitats from tourism, recreational, and fishing activities.