No abstract

a b s t r a c tFrom native pre-Columbian subsistence economies to the modern global economy, mangroves have played an important role providing goods and services to human societies for millennia. More than 90% of the world's mangroves are located in developing countries, where rates of destruction are increasing rapidly and on large scales. In order to design effective conservation strategies, it is critical to understand the natural dynamics and anthropogenic drivers of these coastal wetland habitats. We use retrospective techniques to reconstruct mangrove forest history in the Eastern Tropical Pacific. We examine available, present day estimates of mangrove area and evaluate the representation of mangroves in the protected area systems of Costa Rica, Panama, Colombia and Ecuador, evaluating existing policies regarding mangroves. Archaeozoological evidence shows that mangroves were exploited for many thousands of years by pre-Columbian societies. Post-conquest deforestation prevailed during the next 400 years. Since 1990, despite increasingly positive attitudes towards mangroves and their inclusion in protected areas and conservation policies, mangrove cover has continued to decline due to expanding human activities (agriculture, aquaculture, coastal development), even in the presence of laws prohibiting their removal. Here we provide an historical ecology baseline of mangroves in the Eastern Tropical Pacific, from which to view current trends and map future trajectories. Given the myriad negative consequences of mangrove loss recorded worldwide, and the strong ecological connectivity of the region, developing effective strategies for mangrove management at an appropriate scale will be paramount to protect coastal livelihoods and biodiversity.

The trophic ecology of epibenthic mesopredators is not well understood in terms of prey partitioning with sympatric elasmobranchs or their effects on prey communities, yet the importance of omnivores in community trophic dynamics is being increasingly realised. This study used stable isotope analysis of 15N and 13C to model diet composition of wild southern stingrays Dasyatis americana and compare trophic niche space to nurse sharks Ginglymostoma cirratum and Caribbean reef sharks Carcharhinus perezi on Glovers Reef Atoll, Belize. Bayesian stable isotope mixing models were used to investigate prey choice as well as viable Diet-Tissue Discrimination Factors for use with stingrays. Stingray δ15N values showed the greatest variation and a positive relationship with size, with an isotopic niche width approximately twice that of sympatric species. Shark species exhibited comparatively restricted δ15N values and greater δ13C variation, with very little overlap of stingray niche space. Mixing models suggest bivalves and annelids are proportionally more important prey in the stingray diet than crustaceans and teleosts at Glovers Reef, in contrast to all but one published diet study using stomach contents from other locations. Incorporating gut contents information from the literature, we suggest diet-tissue discrimination factors values of Δ15N ≊ 2.7‰ and Δ13C ≊ 0.9‰ for stingrays in the absence of validation experiments. The wide trophic niche and lower trophic level exhibited by stingrays compared to sympatric sharks supports their putative role as important base stabilisers in benthic systems, with the potential to absorb trophic perturbations through numerous opportunistic prey interactions.

Capture fisheries in small island developing states (SIDS) have the capacity to increase access to vital micronutrient-rich food to tackle malnutrition, but when fishers are restricted to nearshore habitats by limited capacity (boats, engines, fishing gear), fisheries production can be low. This is the case of coastal Timor-Leste, where some of the world's most diverse coral reefs are juxtaposed with one of the world's most undernourished populations. In these settings, interventions that have successfully improved livelihoods from fishing and reduced threats to biodiversity are rare. Elsewhere in the Pacific, nearshore anchored fish aggregating devices (FADs) have shown success in improving catch rates by making pelagic stocks more accessible to small-scale fishers. Here we test the effects of FADs at increasing capture fish production, by deploying eight experimental FADs at four sites around the country and recording catch and effort data from FAD and non-FAD fishing trips. We assess the effects of FADs on catch rates and catch assemblage and the rate of 100% return on investment (RoI). The average longevity of FADs was 11 months. Results show a significant positive effect of FADs on catch rates when controlling for random site variation, with FADs paying for themselves in ∼5 months or less at three out of four sites. Across all sites and fishing types, 63 species were identified, but FAD catches significantly reduced overall assemblage diversity, with three species (Sardinella spp., Decapterus macarellus, Rastrelliger brachysoma) representing 96% of the catch. Despite the relatively short longevity of FADs deployed in Timor-Leste, the fast RoI seen at most sites indicates that FADs are effective in providing livelihood benefits in certain locations. Catch rates were highest where fishers were specialized, invested in FAD fishing, and formed catch sharing groups with access rights to specific FADs. National level investment into a FAD programme by the government could realistically increase overall fish production in the country, thereby improving availability of micronutrient rich fish to combat malnutrition. A deployment program should be coupled with capacity building around group formation and defining access rights to ensure equitable community benefits.