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| Key morphological structures of a single eelgrass (Zostera marina) plant. Typically, leaves are 20 -
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Some eelgrass beds in Atlantic Canada have receded in recent years due to a multitude of interacting stressors including disease, species invasions, nutrient enrichment, and climate change. There have been concerns that aquaculture may also have the potential to negatively impact eelgrass, given aquaculture is primarily a coastal activity. This rep...
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... like all seagrasses, are clonal plants that grow by replicating modules (or ramets) along their rhizome ( Figure 3). These modules consist of: (1) a shoot, which extends into the water column and bears photosynthetic leaves; (2) roots, which anchor the plant in the sediment; and (3) a segment of rhizome, which connects to neighboring modules (Reviewed in Duarte et al. 2006). ...
Citations
... Both of these factors were suggested to be responsible for a reduction in eel grass (Zostera marina) and benthic biodiversity in Port Mouton Bay, Nova Scotia 1 (Cullain et al. 2018). Eelgrass is known for its high biodiversity value and is identified as an Ecologically Significant Species (ESS) in Canada. 1 The potential for aquaculture to impact eelgrass integrations is comprehensively reviewed in 'Managing Aquaculture and Eelgrass Interactions in Nova Scotia' by Howarth et al. (2021). ...
The development of offshore aquaculture is globally gaining momentum in response to increasing space constraints in the coastal zone, and because offshore aquaculture has the potential to generate fewer conflicts and reduced environmental impacts. Due to the large size of Canada’s open ocean and proximity to key markets, there is strong potential to develop offshore aquaculture in Canadian waters, particularly off the coast of Nova Scotia. However, the prospect of developing offshore aquaculture in Nova Scotia raises some important questions regarding federal and provincial jurisdiction.
The Provincial Government of Nova Scotia has a long history of being the lead regulator for commercial aquaculture in Nova Scotia. However, the exact borders delineating Nova Scotian provincial waters and federal offshore waters remains undefined. Currently, there is no comprehensive regulatory system for aquaculture in federal offshore waters. Consequently, the pending Federal Aquaculture Act may include regulations to lease and license offshore aquaculture facilities. However, to avoid continuing uncertainty, its implementation would need to be predicated by a clearly defined provincial-federal offshore border separating the two jurisdictions.
... Interestingly, preliminary investigations in Nova Scotia suggest suspended bag production methods may reduce oyster susceptibility to MSX (Rod Beresford, Cape Breton University, pers. comm, 19 th November 2020) which may have an added advantage of causing less disturbance and shading to seagrass (reviewed in Howarth et al. 2021). Overall, ocean temperatures and salinity in the Northwest Atlantic are projected to continue increasing (see Section 1.2) which will likely improve the growth of these protozoan diseases. ...
Climate change is increasing global ocean temperatures and causing reduction in pH and oxygen. Global sea level is also rising at an accelerating rate, increasing the risk of coastal erosion and flooding. Nova Scotia is highly dependent on coastal resources for employment and infrastructure,and climate change is a threat to coastal communities and industries.
Planning adaptation measures will be more effective than responding to climate change impacts after they occur. A prerequisite for the advanced planning of climate change adaptation are vulnerability assessments, which are needed to help decision-makers prioritize adaptation efforts. The Centre for Marine Applied Research (CMAR), in collaboration with the Nova Scotia Department of Fisheries and Aquaculture (NSDFA), has initiated a project to assess climate change vulnerability of seafood-dependent communities in Nova Scotia.
To support this initiative, CMAR has written a preliminary report reviewing the potential impacts of climate change on coastal communities in Nova Scotia.
This paper reviews the impacts of shellfish and finfish aquaculture on eelgrass Zostera marina, the most widely distributed seagrass species in the northern hemisphere. Shellfish aquaculture can have positive, neutral, and negative effects on eelgrass. Positive interactions can be generated by the filtering activity of cultured bivalves, which may improve water quality and reduce epiphyte loads. Also, shellfish biodeposits may provide more nutrients to eelgrass and other vegetation. However, negative responses are more commonly reported and can be caused by shading and sedimentation. These negative effects tend to occur directly under and immediately surrounding shellfish farms and rapidly diminish with increasing distance. In contrast to shellfish aquaculture, only 1 field study has investigated the effects of finfish aquaculture on eelgrass in a temperate setting, and the results were inconclusive. However, many studies have investigated the effects of Mediterranean finfish farms on 2 other species of seagrass (Posidonia oceanica and Cymodocea nodosa). These studies report clear negative interactions, which have been linked to increased nutrient concentrations, sulphides, sedimentation, epiphyte loads, and grazing pressure. It is unknown if these studies are relevant for finfish aquaculture in temperate regions due to differences in environmental conditions, and that the studies focused on different species of seagrass. Thus, further study in a temperate setting is evidently warranted. We conclude by highlighting key research gaps that could help regulators establish unambiguous operational and siting guidelines that minimize the potential for negative interactions between aquaculture and eelgrass.
