Inter-island nesting dynamics and clutch survival of green turtles Chelonia mydas within a marine protected area in the Bijagós Archipelago, West Africa

Understanding spatial heterogeneity in reproductive success among at-risk populations facing localised threats is key for conservation. Sea turtle populations often concentrate at one nesting site, diverting conservation efforts from adjacent smaller rookeries. Poilão Island, Bijagós Archipelago, Gu...

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Bibliographic Details
Published in:Marine biology 2024-07, Vol.171 (7), p.143, Article 143
Main Authors: Raposo, Cheila, Rebelo, Rui, Catry, Paulo, Ferreira-Airaud, Maria Betânia, Barbosa, Castro, Garcia, Tumbulo Bamba, Regalla, Aissa, Sampaio, Manuel Sá, Patrício, Ana Rita
Format: Article
Language:English
Subjects:
Animal reproduction
Aquatic reptiles
Archipelagoes
Biomedical and Life Sciences
Breeding success
Chelonia mydas
Clutches
Conservation
Density
Freshwater & Marine Ecology
Hatching
Heterogeneity
Interspecific relationships
Islands
Life Sciences
Marine & Freshwater Sciences
Marine parks
Marine protected areas
Microbiology
National parks
Nesting
Nesting behavior
Oceanography
Original Paper
Patchiness
Population dynamics
Population growth
Predation
Protected areas
Reproduction
Reptiles & amphibians
Rookeries
Sea level changes
Sea level rise
Sea turtles
Source-sink relationships
Spatial heterogeneity
Survival
Turtles
Zoology
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Summary:Understanding spatial heterogeneity in reproductive success among at-risk populations facing localised threats is key for conservation. Sea turtle populations often concentrate at one nesting site, diverting conservation efforts from adjacent smaller rookeries. Poilão Island, Bijagós Archipelago, Guinea-Bissau, is a notable rookery for green turtles Chelonia mydas within the João Vieira-Poilão Marine National Park, surrounded by three islands (Cavalos, Meio and João Vieira), with lower nesting activity. Poilão’s nesting suitability may decrease due to turtle population growth and sea level rise, exacerbating already high nest density. As the potential usage of secondary sites may arise, we assessed green turtle clutch survival and related threats in Poilão and its neighbouring islands. High nest density on Poilão leads to high clutch destruction by later turtles, resulting in surplus eggs on the beach surface and consequently low clutch predation (4.0%, n  = 69, 2000). Here, the overall mean hatching success estimated was 67.9 ± 36.7% ( n  = 631, 2015–2022), contrasting with a significantly lower value on Meio in 2019 (11.9 ± 23.6%, n  = 21), where clutch predation was high (83.7%, n  = 98). Moderate to high clutch predation was also observed on Cavalos (36.0%, n  = 64) and João Vieira (76.0%, n  = 175). Cavalos and Meio likely face higher clutch flooding compared to Poilão. These findings, alongside observations of turtle exchanges between islands, may suggest a source-sink dynamic, where low reproductive output sink habitats (neighbouring islands) are utilized by migrants from Poilão (source), which currently offers the best conditions for clutch survival.
ISSN:0025-3162
1432-1793
DOI:10.1007/s00227-024-04463-w