Preliminary notes on the vulnerability of Tripneustes gratilla from increase storminess across the Philippines

Abstract

This paper provides preliminary notes on the vulnerability of selected Tripneustes gratilla populations in the Philippines to climate-induced increase storminess. Typhoons in the Philippines are frequent in the north and less in the south. The abundance and size structure of T. gratilla were gathered over nineteen months (July 2009 January 2011) in three sites across the storminess gradient, from northernmost (Ilocos Norte), mid-southern (Zam-boanga del Norte) and southernmost (Davao del Sur). The different scenarios of vulnerability to climate change were based on their exposure, sensitivity and adaptive capacity. The high exposure to storms in the northern site puts the population of T. gratilla vulnerable to climate change with its low density (6 individuals/100 m 2 ), less juveniles (0.4 individuals/100 m 2 ) and narrow reef habitat. These lower their adaptive capacity because of weak support to natural resilience (e.g., poor recruitment). The southern sites, less expose to storms, are less vulnerable and sensitive with its higher abundance (15 individuals/100 m 2 Murcielagos Bay and 42 individuals/ 100 m 2 Sta. Cruz), more juveniles (12 individuals/100 m 2 in Murcielagos and 14 indivi-duals/100 m 2 Sta. Cruz) and extensive reef habitats that support natural resilience (e.g. good recruitment) and in-creases their adaptive capacities although active fisheries and overexploitation is seen as the controlling factor. There is a need for adaptive measures more to increase its natural resilience (e.g., marine protected areas) to both natural and man-made disturbances.