Reports indicate that we have been experiencing more frequent marine heatwaves recently, and 2023 has been particularly staggering. Since April, sea surface temperatures have been increasing, reaching record highs in both the Atlantic and Pacific oceans.
Differences of just one to two degrees Celsius in the water are enough to disrupt the lives of multiple marine species. Corals, for example, may undergo “bleaching” events, which occur when zooxanthellae – coral’s symbiotic algae – die. This doesn’t necessarily kill corals, but it weakens them. Other factors, like an increase in carbon dioxide in ocean waters or pollution, can also cause bleaching. Since the 1950s, we have lost half of these colourful creatures worldwide. And because coral reefs serve as vital habitats for multiple species, their loss will lead to a decline in biodiversity.
Marine mammals such as seals, dolphins and whales also face challenges. In a recent study published in PLOS One, an international team of scientists looked at how North American marine mammals would be exposed to climate change and how they might respond to changes. Looking at cetaceans (which include whales, dolphins and porpoises) and pinnipeds (like seals, sea lions and walruses), the team saw that an astonishing 72 per cent of these species are highly or very highly vulnerable to the impacts of climate change. Baleen whales, toothed whales, medium-sized whales and dolphins emerged as the most at-risk marine mammals. This vulnerability is mostly driven by shifts in ocean temperature, acidity and dissolved oxygen levels, which affect the availability of food sources and suitable habitats for these creatures.
While more research is needed, reports such as these help other scientists to respond to rising marine temperatures. Conservationists, for example, can predict where animals might go in the face of a changing climate and help them where needed. Ultimately, looking beyond our doorsteps is key, to help protect our oceans and the many creatures that live in them.
This article is from New Humanist's winter 2023 issue. Subscribe now.
