Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998

Abstract

Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience.

Physiological and Biogeochemical Responses of Super-Corals to Thermal Stress from the Northern Gulf of Aqaba, Red Sea

“…Schoepf et al (2013) also found no changes in energy reserves and biomass in P. damicornis under control and elevated temperature conditions (26.5 vs. 29 • C). This is surprising since corals of this genus are often among the most sensitive to thermal stress in other regions (Hueerkamp et al, 2001;Obura, 2001;McClanahan et al, 2004;Guest et al, 2012;Foster et al, 2014;Pisapia et al, 2016) and even suffer lipid losses when bleached (Rodriguez-Troncoso et al, 2016). But there are also cases where Pocillopora corals do not readily bleach compared to other species (Sebastian et al, 2009;Guest et al, 2012).…”

30 Years of Research on Crown-of-thorns Starfish (1986-2016): Scientific Advances and Emerging Opportunities

“…However, outbreaks of Acanthaster spp. are a major contributor to sustained declines in the abundance of reef-building corals recorded at key locations throughout the Indo-Pacific (e.g., GBR, (Osborne et al 2011;De'ath et al 2012); Japan ; Indonesia ; Guam (Caballes 2009); Maldives, (Pisapia et al 2016); French Polynesia, (Trapon et al 2011;Kayal et al 2012)), and certainly have disproportionate impacts on faster-growing corals (section 2.25). Functional replacement of reef-building corals by other habitatforming sessile fauna and flora, may partially offset declines in primary productivity and carbonate production due to widespread coral loss.…”

“…Secondly, outbreaks of Acanthaster spp. remain a major contributor to sustained decline in coral cover at many reefs throughout the Indo-Pacific (e.g., Nakamura et al 2016;Pisapia et al 2016) and scientists and managers alike recognize the critical need to halt and reverse this decline. Preventing and/or containing CoTS outbreaks is generally considered to be one of the most feasible management actions to reduce rates of coral mortality (e.g., De'ath et al 2012), thereby improving the capacity of reef systems to cope with threats due to sustained and ongoing climate change and other more direct anthropogenic disturbances (Anthony 2016).…”

“…The same is probably true for other reef regions, where outbreaks of Acanthaster spp. are among the major causes of acute coral loss (Pratchett et al 2009;Trapon et al 2011;Baird et al 2013;Pisapia et al 2016).…”

“…The same is probably true for other reef regions, where outbreaks of Acanthaster spp. are among the major causes of acute coral loss (Pratchett et al 2009;Trapon et al 2011;Baird et al 2013;Pisapia et al 2016).The purpose of this review is not to provide a comprehensive overview of CoTS biology or research, which are already available elsewhere Birkeland and Lucas 1990;Pratchett et al 2014a), but to consider major advances (and apparent failings) in CoTS research over the past few decades. Our assessment of research progress is based on a critical judgment of the extent to which research (including original research presented within this special issue) has addressed the knowledge gaps highlighted by a seminal review in 1986 (Moran 1986).…”