Impact of abrupt weather change on benthic life: a note on sea hare in a tropical coast, Gujarat, India

Abstract

An oceanographic survey was undertaken in the low slope intertidal zone of the coast of Okha, Gujarat on 7th and 8th January, 2017. The region is represented by mixture of various small scale habitats. On 7th January, live Aplysia oculifera adults were noticed only in the low tide zone (their known habitat) of the northern segment of surveyed region, where green algal beds dominated. The mid to high tide zone was devoid of A. oculifera. But on 8th January, mass mortality of A. oculifera was observed in the entirely sandy high tide zone of the same segment, although January is known to be favourable for adults of the species. We have analyzed the atmospheric and oceanographic parameters such as wind speed, wave height, tidal elevation and tide-time to understand the possible cause behind the mortality event. The mortality event coincided with abrupt change in weather marked by sudden increase in wind speed and wave height, coupled with high tide.