Antonio Pusceddu: Climate Changes Marine Ecosystems

The University of Cagliari professor explains how ocean warming is altering biodiversity, species distribution, and the future of marine habitats. Climate change is profoundly transforming marine ecosystems, and the consequences are already visible in many areas of the planet, including the Mediterranean. University professor Dr. Antonio Pugeddu, who spoke to Unica Radio to explore the relationship between rising temperatures, marine biodiversity, and scientific research. According to Pugeddu, climate change is no longer a prediction but an established reality, due primarily to human activities over the last two centuries. The oceans have so far played a fundamental role in absorbing a significant portion of the carbon dioxide and excess heat produced by human activities, but this process is causing profound environmental changes. The effects of warming on marine organisms One of the most obvious aspects is the increase in water temperatures. The consequences are particularly significant in coastal areas and the surface layers of the oceans, where much of marine biodiversity is concentrated. Many species are struggling to adapt to such rapid change. Sessile organisms, such as corals, are among the most vulnerable because they cannot migrate to more favorable environmental conditions. Prolonged high-temperature events have already caused the loss of large portions of coral reefs in several regions of the world. Mobile species, however, respond by migrating to cooler areas. This phenomenon is altering the geographic distribution of numerous marine organisms and contributing to the so-called tropicalization of the Mediterranean. Alien species and biodiversity Rising temperatures also favor the expansion of species from warmer environments. Some of them are particularly effective at colonizing new habitats, especially in the absence of natural predators. Pugeddu emphasizes how this process can have serious consequences for local ecosystems. Some invasive species compete with native species, reducing biodiversity and altering long-established ecological balances. Among the best-known examples is the blue crab, whose spread across various Italian lagoon environments is causing significant economic and environmental repercussions, especially in the fishing sector. The meaning of thermal tolerance One of the most important tools researchers use to understand the behavior of species is the study of thermal tolerance. Every organism lives within an optimal temperature range that allows for optimal biological performance, such as growth, feeding, and reproduction. When temperatures deviate from these ideal values, survival capacity progressively declines until critical conditions are reached. Through specific experiments, it is possible to construct tolerance curves that allow us to identify the physiological limits of different species and predict how they will react to future climate changes. The role of mesocosms in research To study these phenomena, scientists also use mesocosms, controlled artificial environments that allow them to simulate natural conditions. Within these structures, it is possible to reproduce events such as marine heatwaves and observe how organisms respond to environmental changes. Researchers can monitor parameters such as respiration, egg production, and the behavior of species subjected to different thermal conditions. At the experimental aquaculture laboratory of the University of Cagliari, located in the Santa Gilla lagoon area, these instruments are used to analyze the response of numerous marine species to rising temperatures. Predicting the future of marine habitats The information collected allows for increasingly accurate forecastin