TITLE:
Impact of Habitat and the Rock-Boring Sea Urchin on the White Sea Urchin Population: The Case of Martinique
AUTHORS:
Coralie Borelva, Philippe Joseph
KEYWORDS:
Echinometra lucunter, Tripneustes ventricosus, Marine Environment, Geomorphology, Habitat, Competition, Martinique
JOURNAL NAME:
Natural Resources,
Vol.16 No.13,
December
29,
2025
ABSTRACT: Tripneustes ventricosus and Echinometra lucunter are two species of sea urchins that live in the oceanic waters of Martinique. Both species live in the same habitat and have common food preferences. Martinique is an island with a particular geomorphology with coral reefs in the east (Atlantic part) and slopes of volcanic origin in the west (Caribbean part). The aim of this study is to identify the habitats where white sea urchins are distributed according to the type of substrate and the geomorphology of the seabed. The other part is to assess whether these two species (white sea urchin and rock-boring sea urchin) can compete. Thirty-three sites were sampled in Martinique. Of these sites, four were selected to determine the density of rock-boring sea urchins. The transect method was used to count the number of sea urchins. Other elements were noted: type of substrate, geomorphology, benthic biocenoses, state of health. The results showed that white sea urchins are more numerous in the soft substrate, in the mixed seagrass beds of Thalassia testudinum and Syringodium filiforme. They also live in the hard substrate of coral origin, in fringing reefs (flats and back reef depressions), cays, coral patches and generally in coastal reef platforms. They are rare on the volcanic hard bottoms between Anses d’Arlet and Prêcheur. The population of rock-boring sea urchins is higher than that of white sea urchins between April and December 2024. It appears that the rock-boring sea urchins appear to be taking advantage of the decline in the white sea urchin population to grow.