Lantoasinoro Ranivoarivelo

Seaweed farming offers a sustainable solution to malnutrition and economic challenges in southwestern Madagascar. This study assessed the seasonal performance of 12 edible seaweed species and optimized cultivation parameters for Gracilaria corticata and Gracilaria salicornia using long-line aquaculture. Environmental factors, including temperature, light intensity, salinity, and current speed, were monitored across warm and cool seasons. G. corticata, G. salicornia, and Hormophysa cuneiformis exhibited the highest retention rates (>50 %) and growth performance, with G. corticata demonstrating significant superior growth in both seasons. Smaller cuttings (0–50 g) achieved higher retention and specific growth rates, particularly in the first 30 days. Growth was significantly influenced by light intensity (4209.35 ± 3274.72 lux in the warm season; 3107.77 ± 3194.22 lux in the cool season) and temperature (30.20 ± 1.26 °C in the warm season; 24.83 ± 0.35 °C in the cool season), with optimal conditions occurring in the warm season. These findings highlight the potential of G. corticata and G. salicornia for sustainable aquaculture, contributing to species diversification and food security. Optimizing environmental conditions and cutting sizes is crucial for maximizing seaweed productivity in Madagascar.

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 Shannon-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

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 Shannon-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

The spatial and temporal distribution of macroalgal assemblages at 10 sites in the Baie de Ranobe and Baie de Toliara in southwestern Madagascar were investigated during warm (February to March) and cool (July to August) seasons. Algal species were identified and coverage estimated at six habitats between the shore and 15 m depth, based on surveys with 0.5 m x 0.5 m quadrats along transects of 30 m long by 5 m broad. Ninety eight taxa (53 red, 24 green, 21 brown) were identified of which 42 were edible. Species dominance varied by bay and season, with Sargassum latifolium dominating during the warm season, and Hypnea musciformis and Ulva lactuca prevalent during the cool season. Algal cover did not differ significantly between bays, but cover differed significantly between habitats. S. latifolium, U. lactuca, and H. musciformis were prominent on the algal shelf, Ulva reticulata on the inner shelf, and Amansia rhodantha on the outer shelf. Edible seaweed proportions increased during the cool season, particularly at algal and inner-shelf habitats. Generalized Linear Model analysis confirmed significant differences in edible algal cover across habitats and seasons. The potential of sustainably using macroalgae for aquaculture and human consumption in southwestern Madagascar is highlighted.

Successful conservation projects that restrict or change access to common pool resources require meaningful community participation not only through consultation but also by empowering communities to take a leading role from the early stages of its design. In this study, community participation was assessed in the Tahiry Honko community-led mangrove blue carbon project in southwest Madagascar using the Spectrum of Public Participation tool developed by the International Association for Public Participation. Trends of community participation at village meetings were assessed using the meeting records from 2014 to 2019. Performance in the project activities was assessed based on the indicators of success. It was learned that: (i) careful scheduling of meetings is crucial to avoid community fatigue; (ii) anonymous democratic votes are an effective, inclusive approach to address domination in a group activity and obtain informed consent; (iii) creating a comfortable space for women is vital to promote their participation in decision-making; (iv) voluntary approach with meal compensation is effective to engage all community groups in mangrove replanting; (v) competitive process is crucial to recruit motivated volunteers for mangrove forest patrols; and (vi) dissemination of patrol results is helpful in developing an adaptive strategy in the absence of effective enforcement of rules.