Rare coral and reef fish species status, possible extinctions, and associated environmental perceptions in Mauritius

Abstract

Mauritius is reported to have the highest marine species endemism in the Western Indian Ocean faunal Province but the status of these species has not been evaluated. To address this knowledge gap, 119 reef sites were sampled to evaluate populations of 16 species of rare and endemic reef fish and corals using scuba-based surveys conducted by citizen scientists and marine science professionals. Additionally, we interviewed $1,000 households in 27 coastal villages to determine their perceptions of the environmental concerns and rare and endemic marine species. In general, population numbers of both studied corals and fish were low and distributions were patchy, with little indication that the fisheries management zones were protecting these species. The Mauritian gregory and Mauritian anemonefish were the most abundant species. The Mauritian and Creole damselfishes, which are range-restricted Mascarene endemics, were not observed and potentially extinct. Endemic fish and coral population numbers were higher on the leeward than windward side of the island. The leeward side has higher tourism use and conservation activities that could promote endemic conservation. Environmental concerns of interviewees were high but varied by district and their socioeconomic contexts. Respondents showed an overall concern for the environment and agreed that endemic and rare species had a right to survive. Nevertheless, these rare and endemic coral reef species are threatened by isolation and habitat loss combined with rapid climate and human resource use change. National and district-specific plans of actions could help to secure their futures.

Evolution, Development and Ecology of Anemonefishes

“…Fortunately, many of these species have broad semi-overlapping Indo-Pacific distributions that include places where the impacts are likely to be less severe. Many of the smaller range species lie at the outer limits of the Amphiprion/Premnas distribution, where the level of threat is likely to vary from species to species (McClanahan et al 2021). Our understanding of anemonefish biodiversity is likely a work in progress, with two new species recently recognized for the Pacific (A. barberi, and A. pacificus, Allen et al 2010).…”

“…Some evidence suggests that for marine fishes, small-range endemics tend to have higher population densities than their widespread counterparts at the same locations (Hobbs et al 2010(Hobbs et al , 2011. This has not been evaluated for anemonefishes, although McClanahan et al (2021) showed that the endemic A. chrysogaster at Mauritius is moderately abundant, is broadly distributed around the island, and has a large depth range. A complete understanding of extinction risks for island endemics will require a greater effort in estimating population densities and total population size.…”

Artisanal fishers in small island developing states and their perception of environmental change: the case study of Mauritius

“…Thermal stress affecting corals have been observed by Mattan-Moorgawa et al ( 2012 ), Louis et al ( 2016 ) and McClanahan and Muthiga ( 2021 ). Environmental stressors may also be the reason for extinction of some endemic fish species (McClanahan et al 2021 ). Intuitively, one would expect a higher depletion for the groups of fishers who mainly target the reef species.…”

Photo-physiological responses and thermal tolerance of regionally endemic/rare and morphologically different corals of the Western Indian Ocean

“…Yet, lethal coral bleaching has been increasing in frequency, severity, and geographic scope over the past decades, and thus it is anticipated that this trend will continue (Grottoli et al 2014;Hughes et al 2017) which therefore increases the fragility of reefs (Goldberg and Wilkinson 2004) leading to biodiversity loss (McClanahan et al 2021) and rapid community structural changes (Tebbett et al 2023). To date studies on corals of Mauritius have looked at bleaching and mortality of corals under thermal stress (Bhagooli and Taleb-Hossenkhan 2012;Bhagooli and Sheppard 2012;Bhagooli and Kaullysing 2019;Bhagooli et al 2021b,c;Fai et al 2023;Jeetun et al 2023;Ricot et al 2023).…”