It is found in the intertidal zone and the shallow subtidal, and grows on sandy, muddy and silty substrates.

It was first reported as being naturalized in British Columbia and in the US State of Washington,[5][6][7] but is now considered invasive as far south as California.

[1] Japanese eelgrass is a small species and usually grows on the upper edge of seagrass beds, typically on mudflats exposed at low tide.

[1] In Hong Kong, algae grows on the blades of this seagrass and snails in the species Clithon graze on this epiphytic growth.

[10] One difference between the two is that Z. marina undergoes microbial decomposition more slowly than does Z. japonica so that nutrients are recycled more quickly with the latter, giving alterations in both total productivity and in the structure of the decomposer community.