Are sharks outside protected areas adapted to higher stress?
Brazilian guitarfish are an endemic and endangered species in the south-western Atlantic Ocean. Studying their DNA gives scientists insight into how to ensure the long-term viability of their populations, even in impacted environments. Rodrigo is testing whether guitarfish exposed to anthropogenic pressures such as pollution and fishing express a greater number of stress-adaptation-related genes compared to individuals from protected areas. He will also explore whether guitarfish from protected areas are mixing and moving with those from unprotected areas, using genetic analyses to assess the connectivity between individuals.
Rodrigo Domingues
Growing up near the beaches of São Paulo, Brazil, I developed a deep fascination for marine life from a young age. Spending countless hours surfing, I often pondered the presence of sharks nearby, feeling a blend of awe and respect for these creatures. Their beauty and majesty captivated me, prompting my focus on sharks and rays during my undergraduate studies in marine biology at Santa Cecilia University.
During this formative period, I eagerly explored the diverse marine fauna brought ashore by local fishers each day, though sadly often lifeless. Following my undergraduate studies, in 2009 I began...
Local song: adaptative potential of endemic southwest Atlantic guitarfish to anthropogenic stressors
To test the null hypothesis that Brazilian guitarfish exposed to anthropogenic pressure express a greater number of genes related to adaptation to stressors compared to individuals in preserved areas.
Brazilian guitarfish are endemic and endangered species in the south-western Atlantic, and are among the vertebrates most threatened by extinction. Therefore, it is imperative to study these marine elasmobranchs at the genomic level to understand the molecular mechanisms that can guarantee long-term population viability and conservation, even in impacted environments.
Pseudobatos horkelli, P. percellens and Zapteryx brevirostris, collectively referred to as Brazilian guitarfish, are endemic species that occur from Rio de Janeiro in Brazil to Mar del Plata in Argentina. Since the 1980s, these species have faced severe pressure from overfishing, predominantly due to double trawl fishing in coastal waters. These areas are crucial as they serve as breeding grounds for adult males and pregnant females, and as habitats for juveniles year-round. The intensive fishing has led to significant population declines. For instance, over 11 years (1975–1986), approximately 2.6 million Brazilian guitarfish were captured in southern Brazil alone. Each year, an average of 100,000 pregnant females were caught, each yielding an average of six neonates, resulting in an estimated 600,000 neonates killed annually and a total of 6.7 million over the decade. Furthermore, data on catch per unit effort between 1972 and 2002 revealed a staggering 92% decline in the abundance of Brazilian guitarfish. As a result of these alarming trends, the capture and commercialisation of these species were prohibited across Brazil by Normative Instruction 445.
However, it is crucial to uncover evolutionary paths, ecological roles and conservation strategies for this group, and to address questions about how gene activity relates to population dynamics, environmental interactions and local adaptations across various species. This knowledge can help pinpoint critical areas that require urgent management and conservation efforts for these endangered species. It enables us to better understand how genes coordinate complex traits and adapt to diverse environmental challenges, particularly in endangered elasmobranchs. The fact that these species face serious threats such as overfishing, pollution and habitat loss underscores the critical importance of such research for their survival.
- To identify the primary metals present in the tissues of endemic and endangered Brazilian guitarfish.
- To catalogue a set of genes and their functions, evaluating whether guitarfish species exposed to anthropogenic pressures, such as pollution and fishing, express a greater number of stress-adaptation-related genes compared to individuals from protected areas.
- To assess the connectivity between individuals from impacted and protected areas.