Contrasting Responses in the Niches of Two Coral Reef Herbivores Along a Gradient of Habitat Disturbance in the Spermonde Archipelago, Indonesia

Abstract

Habitat modification of coral reefs is becoming increasingly common due to increases in coastal urban populations. Coral reef fish are highly dependent on benthic habitat; however, information on species-specific responses to habitat change, in particular with regard to trophic strategies, remains scarce. This study identifies variation in the trophic niches of two herbivorous coral reef fishes with contrasting trophic strategies, using Stable Isotopes Bayesian Ellipses in R, along a spatial gradient of changing coral reef habitats. In the parrotfish Chlorurus bleekeri, a roving consumer, the range of δ 15 N and δ 13 C and their niche area displayed significant relationships with the amount of rubble in the habitat. In contrast, the farming damselfish, Dischistodus prosopotaenia, showed a narrow range of both δ 15 N and δ 13 C, displaying little change in niche parameters among sites. This may indicate that parrotfish vary their feeding according to habitat, while the damselfish continue to maintain their turf and invertebrate resources. Assessing isotopic niches may help to better understand the specific trophic responses to change in the environment. Furthermore, the use of isotopic niches underlines the utility of stable isotopes in studying the potential impacts of environmental change on feeding ecology.

Cross shelf gradients of scleractinian corals in the Spermonde Islands, South Sulawesi, Indonesia

“…Understanding the complex interactions and dynamic responses of coral reef communities to multiple stressors is key to predicting future trends and managing reefs to sustain ecosystem services (Edinger et al 1998;Hughes et al 2014;Weijerman et al 2018;Andradi-Brown et al 2020). The coral reef ecosystem in the Spermonde Islands, South Sulawesi, offers an example where coral reef ecosystem disruption comes from anthropogenic activities in the sea and land, with an inshore-offshore gradient (Edinger et al 1998;Hoeksema 2012a;Plass-Johnson et al 2018a). The Fungiidae are one coral taxon exhibiting ecological differentiation in distribution patterns along cross-shelf environmental gradients in the area (Hoeksema 2012b).…”

“…There have been studies on various aspects of reef health and biodiversity across this gradient in the Spermonde Islands over the past decades (Moll 1983;Best et al 1989;CRITC 2012;Hoeksema 2012b), as well as more recent studies on coral reefs and associated biodiversity (Plass-Johnson et al 2018a;Plass-Johnson et al 2018b;Teichberg et al 2018). However, there is a need for updated and/or complementary data on certain aspects of coral community biodiversity, ecology and health.…”

Trophic ecology of shallow and deep reef-building corals

“…Based on the mechanisms associated with how heterotrophy can help corals survive thermal stress events, bivariate isotopic niches (δ 13 C and δ 15 N) can be used to investigate shifts in the ecological niches of reef organisms due to reef disturbance (Letourneur et al 2017;Plass-Johnson et al 2018).…”