Check out these two new articles published on corals and black corals … Enjoy reading
Découvrez ces deux nouveaux articles publiés sur les coraux et les coraux noirs … Bonne lecture
Article 1
“Spatial Patterns of Coral Community Structure in the Toliara Region of Southwest Madagascar and Implications for Conservation and Management”
Cite the article: Botosoamananto RL, Todinanahary G, Razakandrainy A, Randrianarivo M, Penin L, Adjeroud M. Spatial Patterns of Coral Community Structure in the Toliara Region of Southwest Madagascar and Implications for Conservation and Management. Diversity. 2021; 13(10):486. https://doi.org/10.3390/d13100486 (Download PDF)
Received: 30 August 2021 / Revised: 26 September 2021 / Accepted: 2 October 2021 / Published: 5 October 2021
Abstract
The Great Reef of Toliara, on the southwestern coast of Madagascar, has been documented as harbouring flourishing reef communities in the 1960s, but has since been affected by various threats, causing a coral decline last reported in 2008. In 2017, we examined the spatial heterogeneity in coral community structure in the region of Toliara. Coral assemblages were characterized by a marked spatial variability, with significant variation for most of the descriptors among the three major habitats and also among stations within habitats. We recorded high coral cover, with values >40% at six of the 10 stations, which was associated with high abundance of coral colonies. We also documented the return to an Acropora-dominated coral assemblage. While these positive results suggest a recent return to healthier coral assemblages, they must be tempered, as the diversity that we recorded was lower than in the 1960s. Moreover, we found a high cover of algae at several stations, suggesting that the ecosystem is likely close to the tipping point toward a phase shift. Finally, the population size-structure of major coral taxa was positively skewed, with few large colonies to ensure the replenishment of local populations. The marked spatial variation suggests that marine protected areas should integrate a sufficiently large area to capture the scale of this spatial heterogeneity.
Keywords: coral reefs; scleractinian corals; community structure; spatial variability; Madagascar
Article 2
Ecomechanics of black corals (Cnidaria: Anthozoa: Hexacorallia: Antipatharia): A comparative approach
Abstract
Mechanical properties of the skeleton of four antipatharians (the whip species Cirrhipathes anguina and Stichopathes cf. maldivensis, and the branched species Cupressopathes abies and Cupressopathes cf. pumila) living in shallow waters off the southwestern coast of Madagascar were investigated using a three-point bending test. The Young’s modulus did not differ according to species but was significantly higher in the distal segment of colonies, compared with the basal and median segments. By contrast, the flexural stiffness was significantly higher in whip species compared with branched ones, and in the whip species, flexural stiffness was higher in the basal segment compared with the other two segments, an observation consistent with a specific adaptation of the species to a strong current environment. Although both species cohabit identical flow conditions, whip species are able to maintain their stalk in vertical position, whereas branched species can readily bend over. This suggests that the specific flexural stiffness is linked to contrasting feeding strategies of species with different morphologies in a similar strong current environment.