Assessments of Abundance in Mollusk Populations in Two Intertidal Habitats in the Gulf of Nicoya, Costa Rica

After years of over-exploitation of the Gulf of Nicoya, the Marine Area of Responsible Artisanal Fishing of Tárcoles (MARAFT) and the fishing cooperative Coope Tárcoles were established to improve sustainability efforts and increase local involvement in preserving the health of the region’s marine populations. The objectives of this study were to assess the intertidal abundance of gastropods at Caletillas and bivalves at Playa Azul. Using belt-transect samples, average density of the gastropods was determined to be 13,416 snails/ha. Using belt transects and clam guns, two families of bivalves were extracted as in a previous study done in 2014; there was a marked decline in abundance of Tellinidae clams from 2014 to 2016 but no significant difference in density of Donacidae clams over the same period. However, there was a significant difference (p \u3c 0.001) in the average valve length of Donacidae clams collected in 2014 and 2016