Ecological dynamics of Zostera marina (eelgrass) in three adjacent bays in Atlantic Canada

Abstract

We obtained and analyzed a baseline dataset of Zostera marina (eelgrass) dynamics in three adjacent bays in Nova Scotia, Canada. The field sites were Kejimkujik National Park Seaside (Keji), Port l'Hebert (PH), and Port Joli (PJ). Measures of Z. marina growth and production, including shoot density, aboveground and belowground biomass, and shoot productivity, were sampled monthly for 1 year. Physical parameters, including water temperature, suspended solids, nutrients, ice cover, and algal presence, were also measured. Seasonal cycles in shoot density, leaf length, and aboveground biomass of Z. marina were evident at all sites. Shoots persisted throughout the winter; however, shoot density was lowest at PH and Keji due to ice cover. Belowground biomass at all sites did not show seasonal signals. Greatest differences in measured Z. marina parameters were observed at Keji compared with PH and PJ. Restricted water exchange at Keji caused high water temperatures, low flushing rates, and prolific algal growth, probably resulting in lower shoot densities and biomass than in PH and PJ. Our study provides some of the first data on Z. marina dynamics in the Atlantic Canadian region, and will provide a critical baseline for future comparisons of plant condition and estimates of variability in potential monitoring parameters.