No abstract

Understanding the factors shaping patterns of ecological resilience is critical for mitigating the loss of global biodiversity. Throughout aquatic environments, highly mobile predators are thought to serve as important vectors of energy between ecosystems thereby promoting stability and resilience. However, the role these predators play in connecting food webs and promoting energy flow remains poorly understood in most contexts. Using carbon and nitrogen isotopes, we quantified the use of several prey resource pools (small oceanic forage, large oceanics, coral reef, and seagrass) by 17 species of elasmobranch fishes ( n = 351 individuals) in The Bahamas to determine their functional diversity and roles as ecosystem links. We observed remarkable functional diversity across species and identified four major groups responsible for connecting discrete regions of the seascape. Elasmobranchs were responsible for promoting energetic connectivity between neritic, oceanic and deep-sea ecosystems. Our findings illustrate how mobile predators promote ecosystem connectivity, underscoring their functional significance and role in supporting ecological resilience. More broadly, strong predator conservation efforts in developing island nations, such as The Bahamas, are likely to yield ecological benefits that enhance the resilience of marine ecosystems to combat imminent threats such as habitat degradation and climate change.

1. The Bahamas is among the last remaining refuges for the Critically Endangered smalltooth sawfish, Pristis pectinata, and the presence of a distinct 'beacon of hope' population on Andros Island may prove critical to their recovery. Although legislation in The Bahamas protects sharks from exploitation, no such national protection exists for rays, which include sawfishes. Targeted efforts to protect essential habitats coupled with community-led conservation actions provide a path forward for sawfish conservation and recovery.2. Structured interviews were conducted in 2021 (n = 77) with community members that frequent Andros waters to describe the temporal and spatial patterns of sawfish distribution in Andros, and to identify key regions or habitats for sawfishspecific monitoring and potential protection. 3. Sawfish encounters (n = 99) included all life stages and were located throughout coastal and tidal waters of Andros. Comparable numbers of animals were encountered along both coastlines, predominantly on shallow (<2 m), muddy flats close to shore (<1 km). Most notable were encounters with young-of-the-year sawfishes in new regions of Andros, indicating the potential discovery of undocumented nursery habitats. Although most encounters were sightings, 22% (n = 20) of the sawfishes were caught, with just under half of these harvested for food, bait, and/or to keep the rostrum as a decorative item. 4. There is an urgent need for more expansive protection and monitoring of smalltooth sawfishes across their range in Andros and improved education and outreach to prevent further harvest. Recommendations include: (i) the formal development of a national strategy for sawfish conservation; (ii) adding sawfish to the existing shark sanctuary to provide national protective measures; and (iii) community-led outreach and education activities to develop and lead conservation initiatives, including ecotourism and wildlife guiding and a Bahamian sawfish reporting network.