Overfishing and habitat degradation found to cause marine life decline in South Atlantic

Overfishing and habitat degradation have contributed to a significant decline in the marine ecosystems of the South Atlantic Ocean, according to a new research which shed light on the magnitude of human impact on these once thriving marine areas.

The research is based on an archaeological analysis of fish remains from several sites in Brazil.

After comparing the archaeological remains of fish species from the past with the present-day fish populations, the results showed a significant decrease in many of the species, particularly sharks and rays, possibly linked to the escalating human impacts, such as overfishing and habitat degradation in recent decades, according to the study led by Universitat Autonoma de Barcelona (UAB), Spain, in collaboration with universities in Germany and Brazil.

The study is published in the journal PLoS ONE.

The indigenous communities that inhabited the southern coast of Brazil for thousands of years enjoyed abundant and diverse marine ecosystems teeming with large, high trophic level fish and top predators that played an important role in their food security in the past.

This allowed the periodic exploitation of marine life by these populations with simple fishing technology for thousands of years, the study said.

Thiago Fossile, lead author and researcher at UAB and the UAB Department of Prehistory, emphasises the growing anthropogenic pressures faced by aquatic fauna in Brazil, a country known for its stunning beaches and diverse wildlife.

''Many species documented in archaeological sites are now endangered, while for other species there is insufficient data on their distribution and abundance. By using archaeological data, we can gain insight into these lost environments and can redefine conservation baselines,'' said Fossile.

''Hundreds of archaeological sites provide valuable information on past biodiversity, contributing to discussions on fisheries management and conservation,'' said Andre Colonese, senior author of the study and researcher at UAB and the Department of Prehistory at UAB, highlighting the importance of coastal and marine ecosystems in sustaining subsistence fisheries for thousands of years along the Brazilian coast.

''It is amazing what archeological sites can tell us relative to the impacts of ancient human populations on fish biodiversity. Looking at fish characteristics we found evidence that large top predators have long been exploited and recent fisheries have moved towards lower trophic levels. This process is not recent, but instead, has been in place for thousands of years,'' said Mariana Bender, co-author from the Universidade Federal de Santa Maria, Brazil.

''Indigenous environmental stewardship serves as a model for sustainable resource utilization and plays a crucial role in conserving biodiversity in tropical and subtropical regions of South America. Additionally, studies focusing on archaeological faunal remains provide valuable insights into the origins and evolution of these enduring practices,'' said co-author Dione Bandeira of the Universidade da Regiao de Joinville, Brazil.

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