Environmental cues for mass nesting of sea turtles

Abstract

Mass nesting of Olive Ridley sea turtles at Rushikulya rookery exhibit interannaul variability in population size as well as location of nesting site. This year mass nesting was observed over sand spit (0.25 million) and sporadic nesting (0.05 million) at the rookery and the nesting population surpassed all previous records. The present study examines multiple environmental cues (beach width, volume, shoreline change, foreshore slope, sediment grain size, littoral environmental observation, wind speed and direction) during mass nesting events to assess the factor(s) which favour mass nesting and also the reasons for the record mass nesting over a new site (sand spit). Analysis of results indicates that beach/spit to the north of the river mouth with medium width, mild slope and medium sand grain is a favoured location for mass nesting. Near shore oceanographic conditions conducive for mass nesting are low saline near shore surface water, low energy and relatively longer period south southeasterly waves. Local wind burst with a few days lag/lead of the new/full moon appears as one of the most important factors which trigger mass nesting. Environmental cues for selection of mass nesting site and the factor triggering the mass nesting revealed in the present study are of paramount importance for rookery management and conservation of the vulnerable sea turtles.