Effects of Mangrove Forest Rehabilitation on the Growth of Mud Crab (Scylla olivacea) in Pattani Province

Abstract

Mangrove forests are an important resource to maintain the balance of an ecosystem and are a food source for the local communities. Their past abundance has been increasingly under threat, with the area of mangrove forests having continuously decreased and with it, the aquatic species richness. The objective of this study was to investigate the trees, their growth, and biomass of mangrove species after being planted in a forest rehabilitation area (demonstration area located at the Bang Pu Sub–District, Yaring District, Pattani Province) and to compare the growth rate of mud crabs (Scylla olivacea) cultured in the demonstration area at Bangpu sub – district, Yaring District with the abandoned shrimp ponds at Bang Khao sub–district, Nong Chik District, Pattani Province. The study also investigated some environmental factors in these areas over a period of seven months. (July 2023 – February 2024)

The results showed that a total five tree species in the demonstration area were found namely Rhizophora apiculata, Rhizophora mucronata, Bruguiera cylindrica, Avicennia alba and Sonneratia ovata. The total estimated biomass was 13.21 tons/rai (82.56 tons/ha), with 9.97 tons/rai (62.31 tons/ha) of aboveground and 3.24 tons/rai (20.25 tons/ha) of belowground biomass. The crabs cultured in demonstration area and abandoned shrimp ponds had an average growth rate of 0.31 and 0.22 mm./day, respectively. Furthermore, the mud crabs cultured in demonstration area and abandoned shrimp ponds had survival rates of 52.5 % and 42.0 %, respectively. The study related to environmental factors showed that water chemical properties (of ammonia and nitrate) in the demonstration area was within the standard value for coastal aquaculture, but that of the abandoned shrimp ponds exceeded the standard values.