Great white sharks are overheating

New research suggests great white sharks face a unique physiological threat from rising ocean temperatures, potentially disrupting marine ecosystems. | Contesto: cronaca

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• Great white sharks are overheating

Contesto

Great white sharks, the iconic apex predators of the world's oceans, are showing signs of physiological stress and overheating due to rapidly warming seas, according to a new scientific analysis. The study, which synthesizes recent biological and oceanographic data, indicates that these sharks may possess a specific metabolic and thermoregulatory vulnerability that makes them particularly susceptible to temperature increases, even compared to other marine species. This emerging threat poses immediate risks to individual shark health and long-term risks to the stability of the coastal ecosystems they help govern. The vulnerability stems from the great white's unique physiology. As regional endotherms, they maintain a body temperature higher than the surrounding water, a trait that grants them explosive speed and a vast predatory range. However, this evolutionary advantage may become a liability in a warming ocean. The metabolic cost of regulating their internal temperature is immense, and as ambient sea temperatures rise, the gradient they must maintain narrows. This forces their systems to work harder, potentially leading to overheating, reduced efficiency, and increased metabolic demands that cannot be sustained by available prey. The implications of a decline in great white shark populations would cascade through marine food webs. As apex predators, they exert a top-down control on ecosystems, culling sick and weak individuals from seal and sea lion populations and influencing the behavior of mid-level predators. Their absence or even a significant reduction in their hunting efficacy could trigger trophic cascades, leading to unpredictable surges in some species and the collapse of others. This destabilization would threaten commercial fisheries, alter coastal biodiversity, and fundamentally change the character of marine environments from South Africa to California and Australia. This physiological threat compounds existing pressures on great white sharks, which are already classified as globally vulnerable. They face challenges from overfishing, bycatch in commercial gear, and habitat degradation. The new thermal stressor is not a distant future concern but...

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Categoria: cronaca