Final answer:
Water snails primarily contribute to the carbon cycle through decomposition, breaking down organic material and recycling carbon back into the ecosystem for use by plants and other organisms.
Step-by-step explanation:
The primary role of water snails in the carbon cycle is decomposition. Water snails contribute to breaking down organic material and returning carbon to the ecosystem in a form that can be used by other organisms. This is part of the larger process of nutrient cycling, where decomposers like water snails play an essential role in recycling nutrients, including carbon and nitrogen, back into the carbon cycle.
By consuming dead plant and animal matter, water snails break down complex molecules into simpler compounds. This act of decomposition releases nutrients into the soil and water, which plants and other autotrophic organisms can then utilize. Thus, through the process of decomposing organic material, water snails maintain the balance of the carbon cycle in aquatic ecosystems.