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Research Project
Expanding potential in TROPIcal BIOdiversity and ecosystem research towards sustainable life on land
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Publications
Potential biodiversity connectivity in the network of marine protected areas in Western Africa
Publication . Assis, Jorge; Failler, Pierre; Fragkopoulou, Eliza; Abecasis, David; Touron-Gardic, Gregoire; Regalla, Aissa; Sidina, Ebaye; Dinis, Herculano; Serrao, Ester
Marine Protected Areas (MPAs) must function as networks with sufficient stepping-stone
continuity between suitable habitats to ensure the conservation of naturally connected
regional pools of biodiversity in the long-term. For most marine biodiversity, population
connectivity is mediated by passively dispersed planktonic stages with contrasting
dispersal periods, ranging from a few hours to hundreds of days. These processes
exert a major influence on whether threatened populations should be conserved as
either isolated units or linked metapopulations. However, the distance scales at which
individual MPAs are connected are insufficiently understood. Here, we use a biophysical
model integrating high-resolution ocean currents and contrasting dispersal periods to
predict connectivity across the Network of MPAs in Western Africa. Our results revealed
that connectivity differs sharply among distinct ecological groups, from highly connected
(e.g., fish and crustacea) to predominantly isolated ecosystem structuring species
(e.g., corals, macroalgae and seagrass) that might potentially undermine conservation
efforts because they are the feeding or nursery habitats required by many other
species. Regardless of their dispersal duration, all ecological groups showed a common
connectivity gap in the Bijagós region of Guinea-Bissau, highlighting the important role
of MPAs there and the need to further support and increase MPA coverage to ensure
connectivity along the whole network. Our findings provide key insights for the future
management of the Network of MPAs in Western Africa, highlighting the need to protect
and ensure continuity of isolated ecosystem structuring species and identifying key
regions that function as stepping-stone connectivity corridors.
eDNA metabarcoding reveals a rich but threatened and declining elasmobranch community in West Africa’s largest marine protected area, the Banc d’Arguin
Publication . de la Hoz Schilling, Carolina; Jabado, Rima W.; Veríssimo, Ana; Caminiti, Luca; Sidina, Ebaye; Gandega, Cheikhna Yero; Serrao, Ester
Elasmobranchs (sharks and rays) are the most threatened marine vertebrates, particularly in tropical and subtropical areas. Their population status is often poorly understood due to insufficient information. Despite reportedly harbouring critical elasmobranch habitats, the Banc d'Arguin National Park (PNBA) in Mauritania lacks comprehensive and updated information on the diversity of elasmobranch species in the area. We developed a baseline inventory based on morphological and molecular identification and metabarcoding. DNA barcoding of tissue samples from elasmobranch processing sites and freshly sampled specimens was used to build a genetic reference database of local elasmobranch species. The richness and diversity of species in the PNBA were described via metabarcoding of seawater eDNA samples using an elasmobranch-specific assay and our reference database. We detected 27 species, including 12 new species records for the PNBA. We further uncover potentially undescribed species of Gymnura and Torpedo, while taxonomic corrections are noted for previously reported species. In particular, the reportedly abundant Mustelus mustelus was absent from tissue and eDNA samples, while M. punctulatus was detected instead. Taxa that have anecdotally become regionally extinct or rare (e.g., sawfishes, wedgefishes, lemon sharks) were not detected, highlighting local species diversity shifts within the last few decades. Results show that 67.9% of elasmobranch species in the PNBA are threatened with extinction according to the IUCN Red List of Threatened Species. This study emphasises the importance of taxonomic identification in support of species management and provides a baseline to inform future studies and conservation measures to avoid further species losses.
Long range gene flow beyond predictions from oceanographic transport in a tropical marine foundation species
Publication . Tavares, Ana I; Assis, Jorge; Larkin, Patrick D.; Creed, Joel C.; Magalhães, Karine; Horta, Paulo; Engelen, Aschwin; Cardoso, Noelo; Barbosa, Castro; Pontes, Samuel; Regalla, Aissa; Almada, Carmen; Ferreira, Rogério; Abdoul, Ba Mamadou; Ebaye, Sidina; Bourweiss, Mohammed; dos Santos, Carmen Van-Dúnem; Patrício, Ana R.; Teodosio, Maria; Santos, Rui; Pearson, Gareth; Serrao, Ester A
The transport of passively dispersed organisms across tropical margins remains poorly understood. Hypotheses of oceanographic transportation potential lack testing with large scale empirical data. To address this gap, we used the seagrass species, Halodule wrightii, which is unique in spanning the entire tropical Atlantic. We tested the hypothesis that genetic differentiation estimated across its large-scale biogeographic range can be predicted by simulated oceanographic transport. The alternative hypothesis posits that dispersal is independent of ocean currents, such as transport by grazers. We compared empirical genetic estimates and modelled predictions of dispersal along the distribution of H. wrightii. We genotyped eight microsatellite loci on 19 populations distributed across Atlantic Africa, Gulf of Mexico, Caribbean, Brazil and developed a biophysical model with high-resolution ocean currents. Genetic data revealed low gene flow and highest differentiation between (1) the Gulf of Mexico and two other regions: (2) Caribbean-Brazil and (3) Atlantic Africa. These two were more genetically similar despite separation by an ocean. The biophysical model indicated low or no probability of passive dispersal among populations and did not match the empirical genetic data. The results support the alternative hypothesis of a role for active dispersal vectors like grazers.
eDNA metabarcoding for diet analyses of green sea turtles (Chelonia mydas)
Publication . Díaz-Abad, Lucía; Bacco-Mannina, Natassia; Madeira, Fernando Miguel; Neiva, J.; Aires, Tania; Serrao, Ester; Regalla, Aissa; Patrício, Ana R.; Rodrigues Frade, Pedro
Understanding sea turtle diets can help conservation planning, but their trophic ecology is complex due to life history characteristics such as ontogenetic shifts and large foraging ranges. Studying sea turtle diet is challenging, particularly where ecological foraging observations are not possible. Here, we test a new minimally invasive method for the identifcation of diet items in sea turtles. We fngerprinted diet content using DNA from esophageal and cloacal swab samples by metabarcoding the 18S rRNA gene. This approach was tested on samples collected from green turtles (Chelonia mydas) from a juvenile foraging aggregation in the Bijagós archipelago in Guinea-Bissau. Esophagus samples (n=6) exhibited a higher dietary richness (11±5 amplicon sequence variants (ASVs) per sample; average±SD) than cloacal ones (n=5; 8±2 ASVs).
Overall, the diet was dominated by red macroalgae (Rhodophyta; 48.2±16.3% of all ASVs), with the main food item in the esophagus and cloaca being a red alga belonging to the Rhodymeniophycidae subclass (35.1±27.2%), followed by diatoms (Bacillariophyceae; 7.5±7.3%), which were presumably consumed incidentally. Seagrass and some invertebrates were also present. Feeding on red algae was corroborated by feld observations and barcoding of food items available in the benthic habitat, validating the approach for identifying diet content. We conclude that identifcation of food items using metabarcoding of esophageal swabs is useful for a better understanding of the relationships between the feeding behavior of sea turtles and their environment.
Predicted regime shift in the seagrass ecosystem of the Gulf of Arguin driven by climate change
Publication . Chefaoui, Rosa M.; Duarte, Carlos M.; Tavares, Ana I; Frade, Duarte; Sidi Cheikh, M.A.; Abdoull Ba, M.; Serrao, Ester
The Banc d′Arguin is a marine ecosystem of global conservation significance, the largest bird sanctuary of western Africa, supported by one of the most extensive seagrass beds in the world composed by three seagrass species, two temperate near their southern limit (Zostera noltei and Cymodocea nodosa) and one tropical at its northern limit (Halodule wrightii). Here we predict the fate of this seagrass ecosystem under climate change scenarios during the 21st century, using species distribution models and sea level rise estimates. We forecast a probable decline in total seagrass area of 3340 Km2 (78%) by 2100, involving the loss of both temperate seagrasses (Z. noltei, C. nodosa), the foundational ecosystem components. By 2050, only the tropical species (H. wrightii) would remain, which forms thin and sparse shallow stands functionally distinct from the previous tall dense meadows that span wider vertical ranges. Intertidal flats, the essential bird
foraging habitats, would become unvegetated and also suffer a major reduction in area (114 km2 by 2050, 587 km2 by 2100). The large projected loss of foundational seagrass species portends a collapse of major ecosystem functions with profound impacts on biodiversity, fishery resources and ecosystem services.
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Funding agency
European Commission
Funding programme
H2020
Funding Award Number
854248