The role of top-predator in the preservation of coral reefs ecosystem

Abstract

The coral reef ecosystem in Indonesian as part of Coral Triangle Region has been significantly decreasing in the last decades. This damage has been known widely due to coastal development, pollution, and uncontrolled fishing and harvesting. Among other many living species in the environment, the existence of coral reefs is directly related to the existence of Drupella sp. and Acanthaster planci as the coral predators, while the existence of the predators also related to the Napoleon wrasse and Giant triton/ Trumpet shell as the top predator. This study discusses the interaction among the coral reefs, the predators and the top predators, which is represented in a dynamical model of predator-prey-top predator. In the absence of top predators, the system is reduced as a two-predator-prey model with only one surviving predator, Acanthaster planci, which has more effective predation behavior. The role of Napoleon wrasse as a top predator of both Acanthaster planci and Drupella sp. is significantly important to protect the coral reef from the excessive predation from Acanthaster planci and Drupella sp. A stable coexistence is shown between coral reef, Acanthaster planci and Napoleon wrasse. With the appearance of Giant tritons which predate only Acanthaster planci, a coexistence between five species may occur with abundant species of Giant triton.

Assessing population collapse of Drupella spp. (Mollusca: Gastropoda) 2 years after a coral bleaching event in the Republic of Maldives

“…& B. Riegel, 1998), Thailand (Scott et al, 2017a, b) and India (Marimuthu & Tripathy, 2018). These events appeared to be caused by overfishing of natural predators, high coral mortality and changes in temperature and salinity (Turner, 1994a, b;Cumming, 2009a, b), although the causes are complex and still not completely understood (McClanahan, 1994(McClanahan, , 1997Lam & Shin, 2007;Ratianingsih et al, 2017). When these events occur, the damage on coral reefs may be severe reducing coral cover by 35 to 70% (Cumming, 2009a, b).…”

The outbreak of Drupella snails and its catastrophic effects on coral reefs: a comprehensive review

“…Predators of Drupella snails, such as the fish Coris aygula, were seldom observed in investigated region, which may account for the behavior of Drupella snails foraging on the upper surfaces of branching corals and exposed massive or encrusting corals during the daytime, without being constrained by "top-down" control (Shafir et al, 2008). Napoleon wrasses (Cheilinus undulatus), considered one of the natural predators of Drupella snails, can suck the snails out of coral and crush their hard shells using pharyngeal bones (Ratianingsih et al, 2017). However, another study has shown a significant decline in Napoleon wrasses populations in coral reefs (Sadovy et al, 2003).…”

“…Certain organisms can act as predators or competitors of Drupella snails, helping to control their population. The giant triton snail (Charonia tritonis) is considered a predator of various corallivorous harmful organisms (Bose et al, 2017;Ratianingsih et al, 2017). The Australian government has invested $568,000 in studying the reproductive biology of giant triton snails and successfully bred 100,000 juveniles, which will be used for the biological control of corallivorous harmful organisms (Chadwick, 2017).…”

Pioneer assessment on megabenthic community suggest the recent ecological condition of coral reef in Senggigi Beach, Western Lombok Island, Indonesia

“…The declining number of reef fish that prey on drupella snail, such as balistid, diodontid, labrid, lutjanid (McClanahan 1994) and protected Napoleon fish (Cheilinus spp.) (Ratianingsih et al 2017), or other factors, such as the presence of El-Niño, increased water temperature and salinity (Lam et al 2007), stress and disease in corals (Morton et al 2002;Shafir et al 2008) could lead to the drupella's outbreak on a reef.…”