Western Indian Ocean JOURNAL OF Marine Science Volume 17 | Issue 1 | Jan – Jun 2018 | ISSN: 0856-860X Chief Editor José Paula Western Indian Ocean JOURNAL OF Marine Science Chief Editor José Paula | Faculty of Sciences of University of Lisbon, Portugal Copy Editor Timothy Andrew Editorial Board Louis CELLIERS Blandina LUGENDO South Africa Tanzania Lena GIPPERTH Aviti MMOCHI Serge ANDREFOUËT Sweden Tanzania France Johan GROENEVELD Nyawira MUTHIGA Ranjeet BHAGOOLI South Africa Kenya Mauritius Issufo HALO Brent NEWMAN South Africa/Mozambique South Africa Salomão BANDEIRA Mozambique Christina HICKS Jan ROBINSON Australia/UK Seycheles Betsy Anne BEYMER-FARRIS Johnson KITHEKA Sérgio ROSENDO USA/Norway Kenya Portugal Jared BOSIRE Kassim KULINDWA Melita SAMOILYS Kenya Tanzania Kenya Atanásio BRITO Thierry LAVITRA Max TROELL Mozambique Madagascar Sweden Published biannually Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal and marine resources. 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ISSN 0856-860X Cover image: Maputo (© Jose Paula, 2010) WIO Journal of Marine Science 17 (1 ) 2018 111-124 Original Article 111 Marine Biodiversity of La Reunion Island: Echinoderms Chantal Conand 1,2, Sonia Ribes-Beaudemoulin 3, Florence Trentin 4, Thierry Mulochau 5, Emilie Boissin 6 1 UMR ENTROPIE, La Reunion 2 Muséum National Histoire 3 Conservatrice Museum 4 Vie Océane, La Reunion, University, Saint Denis, Naturelle, Paris, de La Reunion, France France France France 5 BIORECIF La Reunion, 6 EPHE-UPVD-CNRS, * Corresponding author: France USR3278-CRIOBE, [email protected] Laboratoire d’Excellence «CORAIL», Perpignan, France Abstract The inventories of marine species of La Reunion (South West Indian Ocean) are still incomplete for several phylum including the Echinodermata. The present knowledge for the five classes is reported here, in the habitats below (1) and above (2) 50 m depth. The overall diversity for (1) is 136 species and for (2), 48 species. On the whole, as in the broader western Indian Ocean, the Holothuroidea and the Ophiuroidea are the dominant classes. Several new spe- cies have been described and many still need further research. Keywords: sea stars, brittle stars, sea urchins, sea cucumbers, feather stars, SWIO Introduction Tallon, 2005; FAO, 2013), for the ophiuroids (Stohr et The South West Indian Ocean (SWIO) is recognized as al., 2008; Hoareau et al., 2013; Boissin et al., 2016; Bois- one of the marine biodiversity hotspots in the world, sin et al., 2017), and the asterids ( Jangoux and Aziz, because of high species richness and endemism (Rob- 1988; O’Loughlin and McKenzie, 2013). Other studies erts et al., 2002). While fishes and corals have long been have focused on the whole phylum in the region (Clark well documented from this area, other groups such as and Rowe, 1971; Rowe and Richmond, 2011), or groups Echinoderms needed further attention. Echinoderms of islands, such as the French programme BIORECIE are a very distinct five-rayed phylum, very important on the Îles Eparses (or Scattered islands) (Conand et al., in marine communities where they play critical roles 2010; Mulochau et al, 2014; Conand et al., 2015). (Purcell et al., 2016). The five extant classes, namely Asteroidea (sea stars), Ophiuroidea (brittle stars), Echi- The current knowledge on the diversity of the noidea (sea urchins), Holothuroidea (sea cucumbers) Echinoderms from La Reunion are reported in and Crinoidea (feather stars) account for more than 7 this paper. This young volcanic island (21.115°S and 000 described species for the world’s oceans (Byrne 55.536°E), is situated 800 km east of Madagascar. and O’ Hara, 2017). Its marine biodiversity needs to be evaluated given the increases of natural and man-induced threats Previous studies had been conducted in several coun- on the narrow fringing reefs, and the high density tries or islands of the SWIO region, on one class, as of human population. The Echinoderms have been for example for the holothurians (Conand and Muth- studied during the last forty years and several pub- iga, 2007; Muthiga and Conand, 2014; Conand, 2008; lications report the ecology of reef populations for Eriksson et al., 2015; Samyn et al., 2006; Samyn and several abundant species of the different classes. 112 WIO Journal of Marine Science 17 (1 ) 2018 111-124 | C. Conand et al. The whole phylum has also been focused on in differ- The total number of littoral species (1) is 136, while the ent programmes conducted during this period, such number of the deep species (2) is 48. as BIOTAS (ANR-06-BDIV-002) (Hoareau et al. 2013; Boissin et al., 2016; Boissin et al., 2017), and BIOLAVE, Diversity by classes on the underwater lava flows of the volcano Piton de Asteroidea diversity la Fournaise (Bollard et al., 2013). Recently, the book Table 2 presents the list of the Asteroidea collected ‘Oursins, Etoiles de mer & autres échinodermes’ and/or observed. The forty-six species belong to six (2016) has been published in French by the authors orders and sixteen families. A few specimens from of the present paper, with many photos and details. the family Ophidiasteridae, Leiaster and Ophidiaster, It is important to present this updated inventory to remain undetermined. the scientific audience and therefore assist in identi- fying new species and allow comparisons with other Twenty-two species are from littoral zones (Table 2 islands or countries in the SWIO. (1)) collected on the coral reefs or from other sandy and rocky biotopes, but are mostly from sparse indi- Methods viduals. During the BIOLAVE programme, 6 species The data from the previous publications on the differ- where collected, including the recently described ent classes have been gathered and updated. Aquilonastra conandae (Bollard et al., 2013). An Anthe- noides aff. marleyi has been found very well conserved The first inventory in English is presented here, for in the stomach of a tiger shark Galeocerdo cuvier caught the five Echinoderm classes, taking into account the at 25 m depth; it was probably recently ingested as it littoral zone, to about 50 m depth, explored by free or was intact, while the other preys were partly digested. scuba diving (1), and deeper zones on the reef-slopes to about 1 000 m (2) which were earlier explored dur- A few species have been studied in more detail: ing different cruises by dredging, such as ‘MD32’ with 1) Acanthaster planci now mauritiensis (see discussion). the ‘Marion Dufresne’ (1982), and the La Reunion Following observations by divers, a study was under- Aquarium team with the ‘Explorer’ (2011-2014). The taken in 1998 based on the results of an inquiry dis- species validity has been checked using Miller et al. tributed to volunteers. From the 352 forms returned (2017), Stöhr et al. (2016) and WoRMS (2018). during two years, the observations by Emeras et al. (2004) concluded that: 1) the distribution was mostly Results on the western coast, with 17% on reef flats, 83% on Echinoderm diversity outer slopes, rarely seen under 20 meters; 2) the pop- The overall diversity for the Echinoderms of La Reun- ulation densities were low (less than 4 individuals per ion is presented in Table 1. 30 minutes dive) and declining from year 2000; 3) the modal size of the individuals was large (40 cm diame- The total number of species presently identified is ter). Only anecdotal observations have been made on 184; 4 specimens are identified at the genus level. the species in La Reunion since that study. Table 1. Echinodermata from La Réunion. Number of species in each class in the littoral zone (1) and the deeper zone (2). ‘Ni’ is number of genera with unidentified species. No. spp Ni spp No. spp Ni spp Total + Ni Littoral (1) Littoral Deep (2) Deep Asteroidea 22 1 24 1 46 +2 Ophiuroidea 38 1 16 54 +1 Echinoidea 34 7 41 Holothuroidea 38 1 38 +1 Crinoidea 4 1 4 +1 Total 136 3 48 1 184 +4 C. Conand et al. | WIO Journal of Marine Science 17 (1 ) 2018 111-124 113 Table 2. Asteroidea from La Réunion. Order Family Species Depth Brisingida Brisingidae Brisinga aff.