Fish larval transport in the coastal waters through ecological modelling

Abstract

The coastal waters of India are rich in diverse marine larval population, and fish larvae form the major commercial group. Larval phase of marine organisms is very important in deciding their future stock and abundance. There are a few obnoxious bioinvasive barnacle larvae, which spread in the coastal waters and form a biofouling agent disturbing harbour, jetties, navigation and recreational activities. Larvae of marine organisms are passively drifted along with the ambient currents from their spawning sites to nursery areas where they develop into juveniles. It is imperative to protect such nursery areas of economically important species, and restrict the areas of dispersion of larvae in the case of obnoxious or bio-invasive species. There are several techniques employed for determining newlinethe larval transport in the marine environment. They include extensive field surveys, screening the larval samples using molecular tools (to distinguish endemic larvae spreading to different locations from their natal sites), attaching markers/ tags and releasing larvae (to find out their extent of retention/ dispersion), quantifying physical parameters like winds, tides and currents to relate the possible passive transport of larval biomass and numerical model as a tool for simulating the larval transport processes. Numerical simulations give a synoptic scale information for a larger area on the larval transport of newlinemarine organisms, compared to other techniques, which provide point data. Further, numerical models once validated for a region can act as a decision support system. Hence, the present study is carried out using numerical modelling techniques, utilising measured / sampled data.