Negus, S. R. B. | Search bioRxiv

bioRxiv2025

The migration of an expanding sea turtle population alters the structure of marine megafauna communities

Interactions shape community structures, yet the impact of large migratory influxes on communities, particularly marine ones, remains elusive. Using drone surveys, we investigated changes of marine megafauna communities (e.g., sharks, rays), during the mass migration of loggerhead sea turtles (Caretta caretta) in Cabo Verde, one of the largest, and growing, rookeries globally and a biodiversity hotspot. In high nesting density areas, with over 6,000 turtles detected in-water at the seasons peak, the community structured with sharks distributing between the turtles and the coastline. In low-density areas ([~]500 turtles), no structuring was detected. After the seasons peak, increased shark abundance and shoreward movement suggest they anticipate a nutrient pulse from emerging hatchlings. Our results highlight the role of sea turtle abundance in structuring marine communities, both as a high-quality food resource (hatchlings) and a likely non-consumable species (adults). Overall, we show the significant impact of migratory species on marine megafauna communities.

ecology↗

bioRxiv2023

Productive foraging sites enhance maternal health and impact offspring fitness in a capital breeding species

Feeding ecology is an essential component of an organisms life, but foraging comes with risks and energetic costs. Species in which populations exhibit more than one feeding strategy, such as sea turtles, are good systems for investigating how feeding ecology impacts life-history traits, reproduction and carried over effects across generations. Here, we investigated how the feeding ecology of loggerhead sea turtles (Caretta caretta) nesting at the Cabo Verde archipelago correlates with reproductive outputs and offspring fitness. We determined the feeding ecology of female turtles before and during the breeding season from stable isotope analysis of carbon and nitrogen, and correlated isotopic ratio with female and hatchling fitness traits. We found that female turtles feeding at higher trophic positions produced larger clutches. We also found that females with less depleted {delta}13C values, typical of productive foraging areas, had greater fat reserves, were less likely to be infected by leech parasites, and produced heavier offspring. The offspring of infected mothers with less depleted {delta}13C values performed best in crawling and self-righting trials than those of non-infected mothers with less depleted {delta}13C values. Overall, our study shows adult female loggerheads that exploit productive areas build capital reserves that impact their reproductive success and offspring fitness. Together, we uphold the suggestion that not all foraging habitats are equal, and can alter the fitness of populations.

ecology↗