A new study reveals that rising ocean temperatures are threatening the legendary warm-bodied Great White shark, and they aren\u2019t alone.<\/p>\n
Some of the ocean\u2019s most powerful predators are warm-blooded creatures that burn nearly four times more energy than their cold-blooded counterparts. The Great White shark is one of these, along with Ireland\u2019s basking shark.<\/p>\n
This rare group of mesothermic fishes, which comprises fewer than 0.1% of all species, retains metabolic heat. This ability allows them to keep parts of their bodies warmer than the surrounding seawater, enabling higher swimming speeds, long-distance migrations, and enhanced predatory performance, according to a press release.<\/p>\n
However, they now face an uncertain future. A new study published in the journal Science suggests that climate change threatens the homeostasis of their environment. Record-high sea temperatures will push these species to their physiological limits, forcing them to dive to cooler depths.<\/p>\n
Scientists from Trinity College Dublin and the University of Pretoria\u2019s Faculty of Veterinary Science developed a novel technique to measure which aquatic species are most endangered by climate change. <\/p>\n
\u201cThe results were really quite striking, and the implications are really sobering,\u201d says Dr. Nicholas Payne from Trinity College. The fastest and most formidable predators of the seas may have just met their match.<\/p>\n
Warm-bodied fish at risk<\/p>\n
The scientists from Trinity and UP created a new framework to estimate the metabolic rate in free-swimming fish, according to the press release. They used tiny sensors to record body and water temperatures, allowing them to understand how much heat fish produce and lose in real-time.<\/p>\n
After analyzing this biologging data, which included factors like body size and temperature, the study authors discovered that mesothermic fishes use about 3.8 times more energy than similarly sized ectothermic (cold-blooded) fishes.<\/p>\n
\u201cA 10\u00b0C (50\u00b0F) increase in body temperature more than doubles a fish\u2019s routine metabolic rate,\u201d explains Dr. Payne. \u201cIn practical terms, this means warm-bodied predators must consume significantly more food to fuel their lifestyle.\u201d<\/p>\n
\u201cBut that heightened energy demand is only part of the story. As fish grow larger, their bodies generate heat faster than they can lose it. This creates a mismatch driven by basic geometry and physics: larger bodies retain heat more effectively, and in mesotherms, high metabolic rates amplify this effect.\u201d<\/p>\n
Climate change: the new predator<\/p>\n
If they exceed the theoretical \u201cheat-balance threshold,\u201d they might overheat, which would inhibit their ability to shed heat to maintain stability without changing their behavior or physiology. For example, a 1-tonne shark<\/a> might start to struggle in waters above 17\u00b0C (62.6\u00b0F).<\/p>\n \u201cAbove such thresholds, fish must slow down, alter blood flow, or dive into cooler depths to avoid dangerous warming, but that comes at a cost. It might be harder to find food or catch it, especially if their main weapon is speed and power,\u201d highlighted Professor Andrew Jackson from Trinity\u2019s School of Natural Sciences<\/p>\n Long admired for their ferocity and speed, these high-performance predators may suffer a high cost, according to this research.<\/p>\n \u201cWhat\u2019s particularly concerning is that these animals are already operating on a tight energy budget, and climate change<\/a> is narrowing their options even further. Understanding these constraints is essential if we want to predict how marine ecosystems<\/a> will shift in the coming decades,\u201d as concluded in a press release<\/a>.<\/p>\n