Effects of climate change on biodiversity, ecosystem functioning and adaptations in aquatic ecosystems

Climate change is causing alterations in the physiology, behaviour, reproductive rates, and overall functioning of organisms in aquatic ecosystems. Organisms living in aquatic environments are highly vulnerable to increasing temperatures, changing rainfall patterns, and extreme weather events. Aquatic photosynthetic organisms—such as seagrasses, phytoplankton, and mangroves—are susceptible to environmental factors, including temperature, light, and acidification, which influence ecosystem productivity and habitat structure. These effects have cascading consequences, transforming not only individual species but also food cycles, interspecies interactions, and ecosystem functions. Organisms may exhibit limited resilience through adaptive mechanisms at the morphological, physiological, behavioural, and genetic levels. However, the speed and capacity of adaptation are constrained by human-induced habitat degradation and extreme weather events. In the future, holistic approaches at both species-specific and ecosystem levels will be critical for maintaining the health of aquatic ecosystems. Long-term monitoring studies, enhancing inter-population genetic diversity and ecosystem connectivity, protecting critical microhabitats, and developing early warning systems are essential for climate change-resilient and sustainable aquatic ecosystems. This article discusses how climate change affects aquatic ecosystems, how aquatic organisms respond to these changes, and how ecological adaptation processes operate.