Final answer:
Water's high specific heat capacity enables it to absorb large amounts of energy with minimal temperature change, moderating climates and helping organisms regulate body temperature.
Step-by-step explanation:
The characteristic that allows the water in aquatic ecosystems to absorb large amounts of energy without a large rise in temperature is its high specific heat capacity. This means water can absorb or release a significant amount of heat with only a minimal change in its own temperature. This property is vitally important for maintaining stable temperatures in aquatic environments, which is essential for the survival of many forms of aquatic life.
Water's high specific heat capacity is also why coastal climates are more moderate and why warm-blooded animals use water to regulate their body temperatures. For instance, the specific heat capacity of water is about five times more than that of sand, explaining why land cools faster than the sea. Thus, water acts as a natural buffer against extreme temperature fluctuations.