Mangroves as Fish Habitat

Sea level Rise Impacts on a Mangrove Ecosystem In Indaramayu, West Java: Implications on Mitigation and Adaptation (Extended Abstract)

Agustinus M. Samosir, Sulistio Sulistiono, and Matt F. Rahardjo


Mangroves in Java have been experiencing significant loss and degradation in the past 25 years; after being extensively cleared and misused as shrimp ponds in the early 1990s, only a few patches of mangrove are left. Some of these remaining mangrove areas have recovered naturally or by rehabilitation programs; however, another threat is impeding the recovery of mangroves. Climate change has been causing devastating damage to the mangrove ecosystems. The damage is from rising sea levels, increased intensity of rain and drought, and acceleration of storms (Ellison 2012). This work aims to identify local vulnerability factors, assess the impact on structures and function of mangrove ecosystems, and formulate adaptation measures for rising sea levels.

Observations were carried out monthly for 6 months in the deltas of Cimanuk River branches in Indramayu, West Java, to see the ecological impact of rising sea level (the area was experiencing long floods in 2008 and 2014) on mangroves and fishes. Two subdeltas were selected to represent an eroded and uneroded mangrove ecosystem, Pabean Ilir (uneroded) and Pagirikan (eroded). Both mangroves are on the Cimanuk delta, have similar land use, and differ only in level of abrasion. The mangroves were further divided into fringing shallow sea, riverine, and fish pond subhabitats. Three locally used types of fishing equipment were employed for sampling each habitat: gill net for the fringing shallow sea, set net for the river, and bamboo fish traps for the fish pond. Diversity and secondary productivity of mangroves and fishes were assessed individually in each subhabitat to see the effect of rising sea level on the structure and function of these ecosystems (Faunce and Serafy 2006). The productivities were classified into three categories: all fish communities, the finfish community, and the dominant fish population. Mangrove vegetation data that were collected included vegetation type, frequency, density, and stand dominance. The measurements were collected within 10 × 10 m2 within each subhabitat. For environmental conditions, water quality was collected from each site, focusing on the key parameters, primary production (chlorophyll content), and salinity. Analysis of variance was utilized to see the differences and similarities within the variables, and a Marxan model was used to formulate alternative conservation zones and measures. These management measures should increase the resilience of the delta to the impact of rising sea levels.