The fate of plastic-wearing sharks: Entanglement of an iconic top predator in marine debris.

Plastic waste is currently a major threat to marine ecosystems, and the ever-growing production of plastic materials suggests that this scenario will not change soon. Understanding cryptic effects of plastic debris on keystone marine species is warranted to address ecosystem-level impacts caused by plastic pollution. This study reports on plastic entanglement in top predator tiger sharks, Galeocerdo cuvier, from the western South Atlantic Ocean. Circular plastic straps produced severe trauma in 3 % of all tiger sharks sampled and led to abnormal anatomical development, indicating worrisome incidence and consequences of plastic entanglement in this species. Removing the plastic strap from one shark which had been entangled for at least 9 months was probably the cause for the shark having experienced post-release mortality. This suggests that, in some circumstances, strap removal is not effective to promote the survival of entangled sharks. Eliminating the circular integrity of plastic materials at first use should contribute to mitigate some of the impacts of plastic pollution on marine megafauna since this shape might be determinant in the process of shark entanglement.

Comparative genomic damage among three shark species with different habits: Sublethal impacts of human origin in a protected island environment in the South Atlantic.

Elasmobranchs can bioaccumulate and biomagnify pollutants. However, few studies are directed to the effects of pollutants on the health of these animals, and in most cases, are limited to the analysis of biochemical markers. Thus, the incidence of genomic damage among shark species inhabiting a protected ocean island in the South Atlantic was investigated in association with the analysis of pollutants in seawater sample. High levels of genomic damage were identified, especially in Negaprion brevirostris and Galeocerdo cuvier, in addition to interspecific variations that may be related to characteristics such as animal size, metabolism and habits. High concentrations of Surfactants were observed in seawater sample, in addition to low concentrations of Cadmium, Lead, Copper, Chromium, Zinc, Manganese, and Mercury. The results evidenced the potential of shark species as a bioindicator of environmental quality and allowed assessing the anthropic impact on the archipelago, which currently drives its economy through tourism.