Which factor has the greatest impact on the distribution of marine species?

Water temperature plays a pivotal role in the distribution of marine species due to its direct influence on various biological and ecological processes. Temperature affects metabolic rates in organisms; warmer water typically accelerates metabolic activities, while cooler temperatures can slow them down. This has implications for growth, reproduction, and survival rates, consequently impacting population dynamics and species distributions.

Different marine species have adapted to specific temperature ranges, which define their habitats. For instance, coral reefs thrive in warm, shallow waters, while many cold-water species are found in deeper, colder oceanic zones. When water temperatures change due to natural variability or anthropogenic influences, it can lead to shifts in species distributions, often causing some species to migrate towards areas that provide suitable thermal conditions.

In a broader ecological context, temperature influences not just individual species, but also the entire community structure and the health of ecosystems. Therefore, while salinity levels, currents and tides, as well as human interference, do impact species distribution, water temperature is often the most significant determinant of where marine species can thrive, given its foundational role in influencing numerous ecological interactions and physiological responses.