Demersal communities on Madagascar’s western shelf and slope
Randrianalisoa, A.N.; Everett, B.I.; Fenessy, S.T.; Bé, J.J.; Ranivoarivelo, L.; Nomenisoa, A.L. (2025). Demersal communities on Madagascar’s western shelf and slope. Western Indian Ocean J. Mar. Sci. Spec. Issue 1: 3547. https://dx.doi.org/10.4314/wiojms.si2025.1.3
In: Western Indian Ocean Journal of Marine Science. Western Indian Ocean Marine Science Association (WIOMSA): Zanzibar. ISSN 0856-860X, more
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| Keywords |
Distribution
Trawls
Chlorophthalmus Bonaparte, 1840 [WoRMS]; Rexea Waite, 1911 [WoRMS]
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| Author keywords |
Demersal marine fauna, Benthic, Diversity, Distribution, Western Madagascar, Western Indian Ocean (WIO) |
| Authors | | Top |
- Randrianalisoa, A.N.
- Everett, B.I.
- Fenessy, S.T.
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- Bé, J.J.
- Ranivoarivelo, L.
- Nomenisoa, A.L.
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| Abstract |
Marine biodiversity research in Madagascar has mostly focused on coastal habitats and deep-sea
ecosystems, with fewer studies on the shelf and upper slope. This study contributes to knowledge of the demersal communities on the west coast of Madagascar using data collected from 54
bottom trawls by the research vessel Dr Fridtjof Nansen in 2008 and 2009. The analyses focused
on two factors: location along the coast and continental shelf versus slope. A total of 239 genera
were identified, consisting of 31,194 individuals with a total weight of 3,335.61 kg. The Shan-
non-Wiener diversity index showed high diversity in the northwest. Diversity was higher on
the slope than shelf. The genus Upeneus dominated all shelf catches (19.35 %) and Rexea (2.18 %)
was strongly dominant on the slope. A clear distinction existed between the shelf and the slope
communities shown by nMDS plots and ANOSIM tests, with R values of 0.67 for the presence/
absence dataset, 0.061 for the abundance dataset, and 0.57 for the biomass dataset. According to
SIMPER analysis, the genera driving the dissimilarity between these two ecosystems are Rexea
and Chlorophthalmus. These results suggest that depth is the most influential factor in determining community assemblages |
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