Benthic life on the tropical sandy shore: Miramar beach a case study

Abstract

Sandy beaches are a dynamic environment in equilibrium, where sand, water and air are in motion, absorbing the energy of the waves and constituting one of the most important aspects of the coastline. Though sandy beaches have been studied for ages, investigators are yet to completely understand the different processes that take place as a result of the dynamic nature of the ecosystems. Coastal ecosystems are exposed to increasing urbanization and industrialization worldwide. Sandy beaches are integral components of these ecosystems and are greatly influenced, usually negatively, by increasing anthropogenic activities. After viewing the rocky shore at low tide, the sandy shore seems barren. The reason for this is that the rocky shores are flourished with fascinating prospect to both layman as well as scientists. Sandy shore has no lush growth of macro-algae and apart from sea-grasses; there is no obvious plant life, except for the odd rock or pebble, which act as a suitable substratum for small plants. Most organisms colonizing the sand live in it rather than on it. This creates a need for a suitable burrowing mechanisms, which may take the form of the proboscis and parapodia of polychaete worms such as the catworm Nephtys, and the lugworm Arenicola or the foot of shore-dwelling bivalve molluscs. The foot of intertidal and subtidal clams such as Mactra violacea and Meretrix spp. is relatively large and powerful. It can pull the shell below the sand surface very quickly symbolising the burrowing life style. Other animals that have evolved for life in sand are the burrowing starfishes and brittle stars. Some animals do not burrow completely. The common shrimp nestles in the ripple marks of the sand and scavenges for carrion. Various crabs live on the surface sediment and uses its two antennae like a snorkel to draw water below the sand for respiration. The cuttle-fish Sepia is one of the larger predators of the sandy shore, moving in at high tide to prey on small fishes. It has astonishing powers of camouflage and can adjust its coloration to match the background.