A mission led by the Algarve Marine Science Centre (CCMAR), in collaboration with local institutions, aimed to map the species of marine invertebrates in the Bijagós Archipelago in Guinea-Bissau. This archipelago has been a UNESCO Biosphere Reserve since 1996. The results revealed a rich and previously unknown local biodiversity, but also highlighted the alarming presence of non-native species in one of West Africa's most intact ecosystems.
The Bijagós Archipelago in Guinea-Bissau is a rare example of balanced coexistence between nature and the local community. While it is in the process of becoming a World Heritage Site and is recognised as one of the richest and least studied ecological regions on the African Atlantic coast, it is made up of 88 islands and islets. In March 2023, the CCMAR team collaborated with the Institute of Biodiversity and Protected Areas (IBAP) and the National Institute for Fisheries and Oceanographic Research (INIPO) to prepare an expedition to collect samples and identify invertebrate species in the archipelago — a group of animals that had not yet been studied in the region.
“Thanks to the excellent collaboration between the Portuguese and Guinean teams, we were able to collect samples in hard-to-reach places and document this previously unknown marine biodiversity in the Bijagós,” says Ester Serrão, the expedition's coordinator and a researcher at the University of Algarve and CCMAR.
With expertise in scientific diving, genetics and morphology, the team also benefited from the special contribution of Peter Wirtz, a marine biologist at CCMAR with extensive experience of the fauna of the Eastern Atlantic and Western Africa. In total, they documented 28 new records of marine invertebrates in the archipelago, including six species never before observed in the Eastern Atlantic. These results show that the marine biodiversity of West Africa remains largely underestimated.
However, the team was most alarmed by the number of non-native species present and their high dispersal capacity. According to the researchers, many of these species likely arrived via passive dispersal, hitching a ride on ship hulls, fishing equipment, or other floating structures. International maritime traffic between the Indo-Pacific, the Caribbean and West Africa is increasingly facilitating this phenomenon.
The scientific mission has resulted in a series of international scientific publications that enhance our understanding of the marine fauna of West Africa. In addition to these new records, the team detected an invasive shrimp, Lysmata rauli, for the first time in the East Atlantic, and found two new shrimp species endemic to the region: Periclimenes africanus and a second, as yet undescribed, species of the genus Palaemon.
‘What we discovered on this expedition is just the tip of the iceberg in terms of the area’s biological complexity,’ says Carlos Moura, lead author of the article published in Ecology and Evolution. The discovery highlights the growing risk posed by the introduction of non-native species — a silent problem with the potential to alter the region’s marine ecosystems profoundly. The researchers emphasise the urgent need for active environmental monitoring to understand Bijagós' biodiversity, identify threats to its marine ecosystems, and implement measures to mitigate the introduction of non-native species.
CCMAR reaffirms its commitment to marine biodiversity research and conservation, and would like to thank all its partners for their support. Special thanks go to INIPO and IBAP in Guinea-Bissau, filmmaker Sylvie Dias and professional diver Nuno Fernandes (Casco Antiguo-Iberagar), who was responsible for the safety of the mission's underwater activities. Funding for this study was provided by FCT – Foundation for Science and Technology and the Aga Khan Foundation under the MARAFRICA project (ref. AGA-KHAN/540316524/2019).
Related articles:
Moura et al. (2025) | Hotspot of Exotic Benthic Marine Invertebrates Discovered in the Tropical East Atlantic: DNA Barcoding Insights From the Bijagós Archipelago, Guinea-Bissau
Wirtz & Moura et al. (2025) | The first record of Lysmata rauli Laubenheimer and Rhyne, 2010 (Decapoda: Caridea: Lysmatidae) from the tropical eastern Atlantic
Fransen & Wirtz (2023) | A New Octocorallia-Associated Shrimp of the Genus Periclimenes (Crustacea, Caridea, Palaemonidae) from West Africa
Moura et al. (2024) | Range extension for Conopea saotomensis (Crustacea; Cirripedia: Archaeobalanidae) in the tropical eastern Atlantic
