Science Advisory Report 2009/018
Does eelgrass (Zostera marina) meet the criteria as an ecologically significant species?
- Eelgrass (Zostera marina) occurs commonly in eastern Canada.
- Under pristine conditions, eelgrass is a persistent and constant habitat feature.
- Loss of eelgrass and other seagrass populations is a worldwide phenomenon largely associated with anthropogenic stresses. Eelgrass populations have been lost in virtually all areas of intense human settlement.
- Eelgrass plays an important role in the physical structuring of the nearshore marine environments by filtering the water column, stabilizing sediment, and buffering shorelines.
- Eelgrass meadows have extremely high levels of primary production, ranking among the most productive ecosystems on the planet.
- Eelgrass adds spatial complexity above and below the substrate creating a three-dimensional habitat that contributes to higher densities and different species compositions than in unstructured habitats, particularly mud/sand flats.
- Numerous species across several phyla (seaweed, invertebrates, fish) utilize the support structures of eelgrass and / or benefit from lower predation rates in vegetated habitat compared to unvegetated areas.
- There are no substitute structuring organisms with the same function as eelgrass that can grow on the sand/mud flats of intertidal and subtidal areas within the salinity ranges occupied by eelgrass. In the absence of eelgrass, these areas would consist of sand/mud flats.
- By being sufficiently abundant and widely distributed, eelgrass often constitutes a dominant habitat feature and has a measurable influence on the overall ecology of adjacent terrestrial and marine ecosystems.
- Eelgrass (Zostera marina) in eastern Canada has characteristics which meet the criteria of an Ecologically Significant Species. If the species were to be perturbed severely, the ecological consequences would be substantially greater than an equal perturbation of most other species associated with this community.
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