Assessing of coral reef resilience on Lembeh Island, North Sulawesi

Abstract

Resilience is the ability of a system to reach equilibrium after a temporary disturbance. When an ecosystem is disturbed, then the recovery of the system is very dependent on the diversity of species that are still left. The remaining communities determine the direction of new successional communities formed after the disturbance has passed, including coral, fish, and other biota communities. This study aimed to determine the level of resilience of coral reef ecosystems on Lembeh Island. The observation was carried out from January 16-19, 2019, at a 7-meter depth. Determination of the coral reef index will refer to coral reef resilience index table. It is found that the resilience of coral reefs on Lembeh Island currently has a high potential for recovery (resilience) from natural stressors based on the 16 parameters. Seven parameters have very high resilience values: the proportion of bleaching resistant species, community resistance to bleaching, taxonomic diversity, size/age distribution, the abundance of reef fish on live coral, and the abundance of coral benthos on live coral and coral disease levels. Lembeh Island is dominated by hard corals measuring between 5.1 to 25 cm (size M) by ~46%, then sizes more than 25 cm (size L) by ~37% and juvenile size (size S) by 17%. The coral health index on Lembeh Island has the capacity to recover if the condition of coral cover is minimally maintained or improved and lower fleshy seaweed cover by increasing the abundance and biomass of herbivorous fish.

Biodiversity of coral reefs ecosystem in Sabu Raijua Waters

“…North Side is impacted by Indonesian Throughflow (ITF), which carries clear and warm water from the Pacific Ocean that supports the coral reefs condition [15]. After all, high coral cover is important in high-resilience coral communities to recover quickly from any disturbance [3]. Top five hard coral lifeform that was found such as Coral Submassive (CS) 5.72 ± 6.49%, Coral Massive (CM) 5.51 ± 4.63%, Coral Encrusting (CE) 4.63 ± 4.66%, Coral Branching (CB) 3.24 ± 5.11%, and Coral Foliose (CF) 1.24 ± 1.57%.…”

“…The highest number of species was found at Deme, which is 30, and the lowest was at Raemedia, which only found 10. Noncoral benthic invertebrates are also affected by the diverse conditions of coral reefs and hard coral cover, such as in Lembeh Strait [3].…”

“…The existence of coastal communities has a chance to emphasize coral reefs on the small island. This incident in several locations, such as Lembeh Island as the effect of Large-Scale ships passing by, Belitung Island as the effect of intensive mining in the coastal areas, and the high intensity of mass tourism [3], [4], [5]. The effect of climate change, such as the intensity of storms also adds some pressure to the coral reef ecosystem.…”