1219 / 2024-09-20 17:37:09

Preliminary Survey on the Biotic Factors Influencing Blood Cockle Culture in Mangrove-Fringed Coastal Ecosystems

Blood cockles, biotic factors, mangrove ecosystems, mudflat

Mangrove ecosystems play a pivotal role as nurseries for marine species, providing biodiversity support and carbon outwelling functions. These ecosystems export organic material and nutrients to adjacent coastal habitats, thereby enriching the productivity of nearby aquaculture zones, including cockle culture areas. In Southeast Asia, where blood cockles (Tegillarca granosa) are cultivated, mangrove-fringed mudflats contribute significantly to nutrient cycling and biodiversity. Despite the advantages of the mudflats ecosystem to support, the cockle production has seen alarming declines. While several abiotic stressors, such as ammonia elevation, sedimentation, and algal food supply fluctuations, have been identified as contributing to this decline, biotic interactions, such as predation, remain underexplored. Current studies examined the extent of the predation risks posed by gastropods at several cockle culture sites along the western coast of Peninsular Malaysia. Preliminary findings revealed substantial portion of empty cockle shells (up to 53.5%) had bore holes resulting from gastropod predation, with further analysis suggests size-selective predation patterns. The cockle beds, often adjacent to mangroves, benefit from the outwelling of organic matter but experience shifts in macrobenthos communities, from bivalve to gastropod dominated communities, corresponding to transition from cockles growing and post-culture recovery periods, respectively, with notable presence of predatory gastropods including the tiger moon snails (Paratectonica tigrina) and thaiad gastropod (Indothais malayensis). Phytoplankton dynamics also play a critical role, as cockles depend on this basal food source. Field studies across Sungai Buloh and Kuala Selangor reveal that nutrient availability, particularly phosphate from mangrove outwelling during the northeast monsoon, promotes phytoplankton proliferation. However, this nutrient enrichment may also facilitate harmful algal blooms, posing additional risks to cockle culture. The results of these studies highlight the interconnected roles of mangrove ecosystems in supporting cockle culture, both through nutrient outwelling and biodiversity maintenance. However, there are still limitations in our understanding of the dynamics of the macrobenthos community in cockle beds, and to what extent it affects cockle production. Future management strategies must address both biotic and abiotic challenges, ensuring sustainable production by leveraging the ecological benefits of mangroves while mitigating environmental stressors.