From the nutrient-rich waters of the Atlantic to the biodiversity hotspots of the Mediterranean, Europe’s seas offer a wealth of rich, dynamic marine ecosystems. These marine and coastal ecosystems provide essential services: they regulate climate by storing carbon, protect shorelines from storms, support fisheries, and offer spaces for transport, tourism and recreation.
Understanding the health of our seas is not always straightforward, but certain species can offer powerful clues. Some organisms actively shape their environment, others signal when conditions begin to deteriorate, and some disrupt the balance when introduced beyond their native range. By looking closely at these functional roles, we can better grasp the complex changes unfolding beneath the surface.
In this article, we explore three such species found in European waters: the native European flat oyster, a builder of underwater habitats; a red algae that reflects environmental stress; and an invasive crab whose rapid spread highlights the consequences of ecological imbalance. Together, they reveal the story of our changing seas.
