Research from the Norwegian University of Science and Technology indicates that warming ocean temperatures are significantly stressing male Calanus finmarchicus copepods, a vital zooplankton species. These males exhibit a greater stress response to heat and chemical-induced oxidative stress compared to females, potentially leading to higher mortality rates. This increased vulnerability in males, who already expend more energy due to active swimming, could disrupt reproduction and survival, threatening the stability of marine ecosystems and the global seafood supply for billions. While the species is not on the brink of collapse, the findings underscore the vulnerability of Calanus finmarchicus to compounding environmental stressors and the critical need to address climate change.