Seahorse ecology and conservation in Brazil: a systematic review

Resumen

Seahorses are unique, charismatic, and threatened fish that inhabit some of the most vulnerable marine environments. In Brazil, three seahorse species are recognized as threatened with extinction; however, knowledge of their ecology and conservation is unsystematized and patchy. Using the PRISMA protocol, we performed a systematic review of the existing literature on Brazilian seahorses to assess the current knowledge on their distribution, life history aspects, threats, and conservation efforts, while also identifying research gaps and proposing future priorities. By accessing 289 studies, we found significant knowledge gaps on distribution, population ecology, and habitat preferences, particularly for Hippocampus patagonicus and H. aff. erectus, including critical taxonomic uncertainties for the latter. Despite being the most studied species in the country, H. reidi lacks updated large-scale studies. We evidenced three major threats to seahorse conservation in Brazil: fisheries (both targeted and incidental), trade, and habitat destruction. Furthermore, we highlight emerging anthropogenic disturbances, such as tourism-related activities, as potential stressors to seahorse populations. Weaknesses in the conservation framework, particularly regarding the regulation and monitoring of these threats, require attention. Our findings provide important insights to direct future management and conservation actions for seahorses in Brazil. We emphasize the need for comprehensive studies to address taxonomic uncertainties, clarify distribution patterns, and understand the life history of seahorses in Brazilian waters. This is especially crucial for populations facing human-induced pressures. Given the complex and multi-stakeholder nature of seahorse threats, a multifaceted conservation approach is essential to ensure their long-term protection in Brazil.