Reproductive strategies in intertidal populations of two co-occurring seagrasses (Zostera spp.)

Reproductive strategies were analyzed in intertidal populations of two seagrasses of the genus Zostera to test the application of r–K selection theory to a novel habitat. Zostera americana has appeared in the study area recently and is spreading rapidly. It grows in the mid to upper intertidal regions and is an r-strategist; i.e., a rapidly growing, essentially annual plant that uses a large proportion (up to 25%) of its resources for flowering. Zostera marina, the native eelgrass, grows in the mid to low intertidal regions and is a K-strategist; i.e., a perennial that uses a large proportion of its resources for maintenance via rhizomes and roots. Considering that the environment becomes less predictable for marine plants on a gradient from the lower to the upper end of the intertidal zone, then the two seagrasses behaved as predicted by the theory.