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Sea urchins, from the phylum Echinodermata, can be perceived to be abundant around the island of Mauritius. Sea urchins can be found in different substrate types; coral reefs, seagrass beds, algae, sand and at different depths. The biodiversity and ecology of this organism has been studied at different levels by many scientists around the globe. Various taxonomic works have been carried out to facilitate the identification and classification of species from this phylum.

AIM:

The aim of this study is to investigate the diversity, abundance and distribution of sea urchins around the coast of Mauritius.

SPECIFIC OBJECTIVES:

The specific objectives are:

To analyze the species distribution and abundance of sea urchin around the coastal sites of Mauritius;
To determine the density, species richness, diversity and evenness of the species;
To determine the different size classes, substrate types and zonation of the species.

Purple Paracentrotus lividus, Stomopneustes variolaris, white Paracentrotus lividus, Tripneustes gratilla, Echinometra mathaei, and Toxopneustes pileolus, listed from being most abundant to the least abundant.
purple Paracentrotus lividus was found to be the most abundant showing a dominance over the other species. More individuals were found from the size class 6<r/cm>10 compared to the other size classes.
The preferred substrate has been found to be coral and coral rubbles because of the presence of both food and shelter from predation, or most probably that mature adults prefer this as a substrate over seagrass beds and sand.

PEARCE, C., DAGGETT, T. and ROBINSON, S. (2004) "Effect of urchin size and diet on gonad yield and quality in the green sea urchin (Strongylocentrotus droebachiensis)", Aquaculture, 233(1-4), pp. 337-367. doi: 10.1016/j.aquaculture.2003.09.027.

Diversity and abundance of sea urchins around Mauritius

Mithila Devi KISSOON¹ and Sushma MATTAN-MOORGAWA^1,2*

¹Department of Biosciences, and Ocean studies, Faculty of Science, University of Mauritius, Réduit 80837, Republic of Mauritius;

Emails: mithila.kissoon@umail.uom.ac.mu; s.moorgawa@uom.ac.mu

Conclusion

Methodology

References

Results

Introduction

Acknowledgements:

The authors are grateful to the Department of Biosciences and Ocean Studies, Faculty of Science, University of Mauritius, Mauritius for logistics support; the Ministry of Blue Economy, Fisheries, Marine Resources and Shipping, Mauritius for permit for sample collection; and the Higher Education Commission, Mauritius, for partial funding.

4.1 species density across site

Figure 4.1 Species density across site, 4.2 species richness across sites, 4.3 diversity across sites, 4.4 density of species per substrate across all sites.

4.2 Species richness across sites

4.3 Diversity across sites

MAIN FINDINGS

Species encountered: Tripneustes gratilla (Linnaeus, 1758)- A; Echinometra mathaei (Blainville, 1825)- B; Paracentrotus lividus (Lamarck, 1816)- C; Paracentrotus lividus (Lamarck, 1816)- D; Stomopneustes variolaris (Lamarck, 1816)- E; Toxopneustes pileolus (Lamarck, 1816)- F

Density: Flic en Flac has the highest density of 3.01, out of all the other sites surveyed.
Species richness: Flic-enFlac, Wolmar and Belle Mare were observed to have the highest species richness, 5.

Diversity: Palmar has been seen to be the most diverse with a diversity index of 1.25

The substrate that was found to be abundant with the species was coral and coral rubbles with purple Paracentrotus lividus having the highest density, 0.224 individuals/m2, for coral/coral rubbles as a substrate, 0.042 individuals/m2 for sand and 0.014 individuals/m2 for seagrass.

4.4 Density of species per substrate across all the sites

The GPS coordinates of each transect was noted.

Water quality parameter

Temperature
Salinity
pH
Dissolved Oxygen

Photo-physicological condition

Species encountered
Species abundance
Species Density
Species richness
Diversity
Species size class
Substrate type and distribution

RW-2021 Submission 136

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