Abstract
James Bay, the southern extension of Hudson Bay, harbours extensive eelgrass ( Zostera marina L.) meadows all along its eastern coast. Within the environmental monitoring programme of the La Grande hydroelectric complex, the James Bay Energy Corporation has studied these eelgrass meadows over a period of several years. Here we present their main features as observed at three permanent sampling stations. Subtidal meadows are all found between depths of 0.5 and 4.0 m (mean low water level (MLWL)) on fine sand and silty clay sediments. Leaf biomass varies between 30 and 675 g dry weight (DW) m −2, and shoot densities from 50 to 1500 m −2. Reproductive shoots average 5% of the population, but can in some places reach 20%. Results indicate large variations, both in density and biomass, with depth, season and from year to year. Natural variability in climatic conditions appears to be responsible for these variations. In James Bay, the eelgrass beds do notsupport a high diversity of associated fauna.
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