Effects of disturbance by clipping on two distinct forms of Zostera marina L.

Abstract

Biweekly clipping of leaves was used as a type of disturbance to compare the responses of eelgrass (Zostera marina) in shallow and deep water to those predicted from a terrestrial ecosystem succession model. All clipped plants had lower leaf growth rates than controls. Clipped plants decreased root-rhizome biomass in shallow water, but not in deep-water stands during 1981. During 1982 (better weather), shallow-water plants increased leaf carbon concentrations; deep-water plants decreased root-rhizome biomass. Root-rhizome to leaf ratios (high in shallow water and low in deep water) and weather conditions appeared important in determining the response to clipping. All plants had similar nitrogen content. These responses were typical of those reported for the tropical turtle grass, but were contrary to differences in plant growth strategies and nutrient use predicted from some terrestrial ecosystem studies of other higher vascular plants.