This collection of eelgrass data has been collated to produce a national map of the location and distribution of eelgrass beds across Canada. The data providers collaborating in this initiative include Federal, Provincial and Municipal government departments and agencies, academia, non-governmental organizations, community groups, private sector, Indigenous groups and independent science organizations. The National Eelgrass Task Force (NETForce) is a collaborative, diverse and inclusive partnership of scientists, managers, and stakeholders working towards a concrete vision which is to create a national map of eelgrass distribution in Canada that is publicly accessible, dynamic, and useful for monitoring and collective decision-making. The eelgrass data were collected using various mapping techniques including species distribution models, benthic sonar, field measurements of habitat presence or absence, video transects, aerial photography, field validation, literature review, satellite imageries, LiDAR, Airborne spectrographic imaging, and Unoccupied Aerial Vehicle (UAV). The metadata provided by the partners relevant for their own projects and the field names were made similar for the compiled dataset. We also created additional fields that differentiated the datasets, and these include data provider, institution code, water body, mapping techniques, province, biogeographic region, eelgrass observation... Other fields are included depending on the original metadata provided by the data provider (i.e. eelgrass percentage cover, eelgrass density, map reference, image classification technique). The data span from 1987 to present, with some eelgrass beds being surveyed only once while others were sampled across several years. Uncertainty information associated with a dataset is included in the metadata when available. This map is intended to be evergreen and more eelgrass data will be added when available. This compiled dataset has been collected by many organizations for different purposes, using different survey techniques and different methodologies and, therefore, considerable care must be taken when using these data. For further information concerning specific datasets contact the data provider/institution and/or see the associated technical report (if available) included in the Report folder under the ‘Data and Resources’ section.This group of eelgrass data has been divided using the geographic boundaries of the Federal Marine Bioregions (https://open.canada.ca/data/en/dataset/23eb8b56-dac8-4efc-be7c-b8fa11ba62e9). The title of each geodatabase (FGDB/GDB) contains the name of the bioregion.The Data Dictionary guide provides the fields description (English and French) from each layer included in the geodatabases.For additional information please see:Gomez C., Guijarro-Sabaniel J., Wong M. 2021. National Eelgrass Task (NET) Force: engagement in support of a dynamic map of eelgrass distribution in Canada to support monitoring, research and decision making. Can. Tech. Rep. Aquat. Sci. 3437: vi + 48 p. https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/4098218x.pdfGuijarro-Sabaniel, J., Thomson, J. A., Vercaemer, B. and Wong, M. C. 2024. National Eelgrass Task Force (NETForce): Building a dynamic, open eelgrass map for Canada. Can. Tech. Rep. Fish. Aquat. Sci. 3583: v + 31 p. https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/41223147.pdf

This dataset includes metrics of eelgrass size, cover, and biomass from field sites along the Atlantic coast of Nova Scotia, Canada. Field sites were located across a gradient of environmental conditions, and field sampling was conducted in July to August 2022. Eelgrass percent cover, shoot density, and plants were sampled at 10 haphazardly distributed sampling stations within each eelgrass bed at approximately the same depth. Stations were ~10m apart and at least 2m from any eelgrass-bare interface. At each sampling station eelgrass leaves in a 0.5 x 0.5m quadrat were photographed for later computer image analysis to determine percent cover. The number of shoots were then counted in a 0.25 x 0.25m quadrat, and 3 vegetative shoots were collected. Shoots were measured for leaf length, width, and weight in the laboratory. These data were used to determine allometric and cover-biomass relationships for use in non-destructive estimation of bed biomass. Cite this data as: Wong, M.C., & Thomson, J. A. Data of eelgrass (Zostera marina) plant size (length, width), cover, and biomass from the Atlantic Coast of Nova Scotia. Published: February 2025. Coastal Ecosystems Science Division, Maritimes Region, Fisheries and Oceans Canada, Dartmouth NS.For additional information please see:Thomson, J. A., Vercaemer, B., & Wong, M. C. (2025). Non-destructive biomass estimation for eelgrass (Zostera marina): Allometric and percent cover-biomass relationships vary with environmental conditions. Aquatic Botany, 198, 103853. https://doi.org/10.1016/j.aquabot.2024.103853

A global decline in seagrass populations has led to renewed calls for their conservation as important providers of biogenic and foraging habitat, shoreline stabilization, and carbon storage. Eelgrass (Zostera marina) occupies the largest geographic range among seagrass species spanning a commensurately broad spectrum of environmental conditions. In Canada, eelgrass is managed as a single phylogroup despite occurring across three oceans and a range of ocean temperatures and salinity gradients. Previous research has focused on applying relatively few markers to reveal population structure of eelgrass, whereas a whole genome approach is warranted to investigate cryptic structure among populations inhabiting different ocean basins and localized environmental conditions. We used a pooled whole-genome re-sequencing approach to characterize population structure, gene flow, and environmental associations of 23 eelgrass populations ranging from the Northeast United States, to Atlantic, subarctic, and Pacific Canada. We identified over 500,000 SNPs, which when mapped to a chromosome-level genome assembly revealed six broad clades of eelgrass across the study area, with pairwise FST ranging from 0 among neighbouring populations to 0.54 between Pacific and Atlantic coasts. Genetic diversity was highest in the Pacific and lowest in the subarctic, consistent with colonization of the Arctic and Atlantic oceans from the Pacific less than 300 kya. Using redundancy analyses and two climate change projection scenarios, we found that subarctic populations are predicted to be more vulnerable to climate change through genomic offset predictions. Conservation planning in Canada should thus ensure that representative populations from each identified clade are included within a national network so that latent genetic diversity is protected, and gene flow is maintained. Northern populations, in particular, may require additional mitigation measures given their potential susceptibility to a rapidly changing climate.Cite this data as: Jeffery, Nicholas et al. (2024). Data from: Variation in genomic vulnerability to climate change across temperate populations of eelgrass (Zostera marina) [Dataset]. https://doi.org/10.5061/dryad.xpnvx0kp2

This is a collection of eelgrass (Zostera marina) presence and absence records collected between 2009-2025 in coastal waters in Nova Scotia, Canada. The data collection has been collated by the Coastal Benthic Ecology Lab (CBEL) at the Bedford Institute of Oceanography, Fisheries and Oceans Canada (DFO) under the supervision of Dr. Melisa Wong. Records include those from various research groups at DFO, Nova Scotia provincial departments, academia, and non-profit organizations.Data were collected using various methods including field measurements of eelgrass presence or absence via boat, snorkel and drop camera video transects, surface observations, and various sample collections (including plants, core, sediment, trawl, pop net, seine, etc.). Please see specific record references for associated metadata and detailed descriptions of the methods for eelgrass occurrence data collection. Where available, water depth (m) and substrate type (rock, soft, or mixed) are provided. The substrate type (hard substrate, mixed, mud, rocky, sand, or various combinations) used for the species distribution model published by O’Brien et al. 2022 is also provided where available.The data owner, data source (i.e., reference(s)), and use of the data in the species distribution model of O’Brien et al. 2022 are provided. All records from sources external to DFO are included under data sharing agreements or permission from the data owner.Cite this data as: Wong, M.C., Fraser, M., Thomson, J. A., O’Brien, J. Data of eelgrass (Zostera marina) occurrences in Nova Scotia. Published: April 2026. Coastal Ecosystems Science Division, Maritimes Region, Fisheries and Oceans Canada, Dartmouth NS.

This shapefile dataset was designed using polygons extracted from the Cartography of Coastal Ecosystems of Maritime Quebec geodatabase (2022, Laboratory for Dynamics and Integrated Management of Coastal Zones, Fisheries and Oceans Canada), described in the paragraph below. It consists of polygons with eelgrass and incorporates attributes describing the vegetation cover, the composition of the seagrass beds, the associated ecosystem name, the imagery data that allowed photo-interpretation and the presence or absence of field data. A unique sequence number associated with each polygon makes it possible to trace the paired polygon of the geodatabase of coastal ecosystems to attribute values not detailed in this shapefile. The study area includes all of the estuarine and maritime coasts of Quebec, with the exception of certain sectors, including most of the Lower North Shore and Anticosti Island, with the exception of villages of Kegaska, la Romaine, Chevery, Blanc-Sablon and Port-Menier. Some islands off the estuary and gulf coasts are part of the region covered, such as Île d'Orléans, Isle-aux-Coudres, Île Verte and Île Bonaventure.The Mapping of Coastal Ecosystems of Maritime Quebec was carried out jointly by the Laboratory for Dynamics and Integrated Coastal Zone Management (LDGIZC) of the University of Quebec at Rimouski as part of the Coastal Resilience Project; and by the Fisheries and Oceans Canada team, as part of the Integrated Marine Response Planning Program (IMRP). A classification of coastal ecosystems was carried out on more than 4,200 km of coastal corridor, focusing on estuarine and maritime coasts of Quebec located between the limit of the upper foreshore and the shallow infralittoral (about 10m deep). The mapping method developed is based on semi-automated segmentation and a photo-interpretation of coastal ecosystems, using very high resolution multispectral photographs (RBVI) acquired between 2015 and 2020 by DFO. The classification of polygons is based on the assignment of predefined value classes for the biological and physical attributes under study (e.g., substrates, plant type, vegetation cover, geosystem, etc. ). Helicopter-born oblique photographs and field data helped to reduce the uncertainty associated with photo-interpretation. UQAR and DFO conducted field sampling campaigns targeting the mediolittoral (4,390 stations) and the lower mediolittoral and infralittoral zones (2,959 stations), respectively , which validated some of the attributes identified by photo-interpretation and provided detailed information on community structure . The geodatabase of the Mapping of coastal ecosystems is hosted and managed by UQAR on their SIGEC-Web cartographic platform: https://ldgizc.uqar.ca/Web/sigecwebCredits © DFO (2023, Fisheries and Oceans Canada)Provencher-Nolet, L., Paquette, L., Pitre, L.D., Grégoire, B. and Desjardins, C. 2024. Cartographie des macrophytes estuariens et marins du Québec. Rapp. Tech. Can. Sci. halieut. Aquat. 3617 : v + 99 p.Grégoire, B., Pitre, L.D., Provencher-Nolet, L., Paquette, L. and Desjardins, C. 2024. Distribution d’organismes marins de la zone côtière peu profonde du Québec recensés par imagerie sous-marine de 2017 à 2021. Rapp. tech. can. sci. halieut. aquat. 3616 : v + 78 p.Grégoire, B. 2022. Biodiversité du relevé côtier Planification pour une intervention environnementale intégrée dans l’estuaire et le golfe du Saint-Laurent (2017–2021). Observatoire global du Saint-Laurent. [Jeu de données]Jobin, A., Marquis, G., Provencher-Nolet, L., Gabaj Castrillo. M. J., Trubiano C., Drouet, M., Eustache-Létourneau, D., Drejza, S. Fraser, C. Marie, G. et P. Bernatchez (2021) Cartographie des écosystèmes côtiers du Québec maritime — Rapport méthodologique. Chaire de recherche en géoscience côtière, Laboratoire de dynamique et de gestion intégrée des zones côtières, Université du Québec à Rimouski. Rapport remis au ministère de l’Environnement et de la Lutte contre les changements climatiques, septembre 2021, 98 p.

This dataset includes metrics of eelgrass traits related to bed structure, morphology, and physiology from field sites along the Atlantic coast of Nova Scotia, Canada. Field sites were located across a gradient of temperature and light conditions. Sampling was conducted in July to August, in 2017, 2021, and 2022. Seagrass density and plants were sampled at 10 haphazardly distributed sampling stations within each seagrass bed at approximately the same depth. Stations were ~10m apart and at least 2m from any seagrass-bare interface. Quadrats were used to determine vegetative and reproductive shoot density. Three plants from each sampling station were collected and processed in the laboratory for length and width leaf 3, number leaves per shoot, rhizome width, rhizome water soluble carbohydrates, and total leaf chlorophyll. Also included in this data temperature and light metric that summarize temperature and light conditions during the summer period.Cite this data as: Wong, M.C., Dowd, M. Data of eelgrass (Zostera marina) traits from the Atlantic Coast of Nova Scotia. Published: February 2025. Coastal Ecosystems Science Division, Maritimes Region, Fisheries and Oceans Canada, Dartmouth NS.For additional information please see:Wong, M.C., Dowd, M. Eelgrass (Zostera marina) Trait Variation Across Varying Temperature-Light Regimes. Estuaries and Coasts 48, 13 (2025). https://doi.org/10.1007/s12237-024-01439-3

This dataset was designed for Environment and Climate Change Canada's (ECCC) National Environmental Emergencies Center (NEEC) for oil spill preparedness and response. The polygons from this layer come mainly from the coastal ecosystems geodatabase as part of the Mapping of coastal ecosystems of the Estuary and Gulf of St. Lawrence project. This layer represents semi-vegetated and vegetated zones of which eelgrass is the dominant vegetation. The study area includes all of the estuarine and maritime coasts of Quebec, with the exception of certain sectors, including most of the Lower North Shore and Anticosti Island, with the exception of villages of Kegaska, la Romaine, Chevery, Blanc-Sablon and Port-Menier. Some islands off the estuary and gulf coasts are part of the region covered, such as Île d'Orléans, Isle-aux-Coudres, Île Verte and Île Bonaventure.The Mapping of coastal ecosystems of the Estuary and Gulf of St. Lawrence was carried out jointly by the Laboratory for Dynamics and Integrated Coastal Zone Management (LDGIZC) of the University of Quebec at Rimouski as part of the Coastal Resilience Project (https: //ldgizc.uqar.ca/Web/projets/projet-resilience-cotiere) funded by the MELCC; and by the Fisheries and Oceans Canada team, as part of its Integrated marine response planning (IMRP) component of the Oceans Protection Plan (OPP), with the objective of updating the Marine Oil Spill Preparedness and Response Regime of Canada. The master geodatabase of coastal ecosystems is hosted and distributed by UQAR on their SIGEC-Web mapping platform: https://ldgizc.uqar.ca/Web/sigecwebThe characterization of eelgrass beds was mainly carried out using photo-interpretation of RVBI aerial photos acquired by DFO (2015-2020) and oblique photos taken by helicopter by UQAR in 2017. This dataset also includes the information from validation stations visited by UQAR (2018-2020). Data from sampling stations, carried out aboard small boats during DFO field campaigns (2017-2021), were also used to validate and refine the photo-interpretation.This dataset also includes eelgrass beds characterized in the Basse-Côte-Nord (MRC Le Golfe-de-Saint-Laurent) by the Agence Mamu Innu Kaikusseht (AMIK) as part of the project ''Involvement of Innu communities in the protection of species at risk and their habitats 2010-2011''. These data were produced during aerial overflights at low altitude (200m and 400m) of the foreshore, as 2 observers circumscribed and documented the covering of eelgrass beds.Credits © UQAR-MPO-AMIK (2023, Laboratoire de dynamique et de gestion intégrée des zones côtières, Pêches et Océans Canada, Agence Mamu Innu Kaikusseht) Provencher-Nolet, L., Paquette, L., Pitre, L.D., Grégoire, B. and Desjardins, C. 2024. Cartographie des macrophytes estuariens et marins du Québec. Rapp. Tech. Can. Sci. halieut. Aquat. 3617 : v + 99 p.Grégoire, B., Pitre, L.D., Provencher-Nolet, L., Paquette, L. and Desjardins, C. 2024. Distribution d’organismes marins de la zone côtière peu profonde du Québec recensés par imagerie sous-marine de 2017 à 2021. Rapp. tech. can. sci. halieut. aquat. 3616 : v + 78 p.Grégoire, B. 2022. Biodiversité du relevé côtier Planification pour une intervention environnementale intégrée dans l’estuaire et le golfe du Saint-Laurent (2017–2021). Observatoire global du Saint-Laurent. [Jeu de données]Nadeau, V., Le Breton, S. 2011. Inventaire aérien des herbiers de zostère de la Basse-Côte-Nord du Golfe du Saint-Laurent. Agence Mamu Innu Kaikusseht. 25 p.Jobin, A., Marquis, G., Provencher-Nolet, L., Gabaj Castrillo. M. J., Trubiano C., Drouet, M., Eustache-Létourneau, D., Drejza, S. Fraser, C. Marie, G. et P. Bernatchez (2021) Cartographie des écosystèmes côtiers du Québec maritime — Rapport méthodologique. Chaire de recherche en géoscience côtière, Laboratoire de dynamique et de gestion intégrée des zones côtières, Université du Québec à Rimouski. Rapport remis au ministère de l’Environnement et de la Lutte contre les changements climatiques, septembre 2021, 98 p.

Seagrasses support multiple key ecosystem functions (e.g., sediment stabilization, carbon storage, nursery habitat) in nearshore environments across all three Canadian coastlines. Eelgrass (Zostera marina) is a seagrass species that has been designated as an Ecologically Significant Species (ESS) and is the most widely distributed and abundant seagrass in Canada. Given the considerable conservation and management interest in eelgrass habitats, large-scale data aggregation efforts have been initiated to generate comprehensive distribution maps of eelgrass coverage in Canadian coastal waters. However, extensive portions of the Newfoundland coastline have not yet been surveyed for the presence of eelgrass. We combine spatial data layers describing shoreline characteristics, relative exposure index (REI), depth, and freshwater inputs to delineate areas potentially suitable for eelgrass growth in Newfoundland. We determined that many nearshore environments could potentially support eelgrass habitats but confirming eelgrass presence will require further validation and ground-truthing. Incorporating distribution models that use environmental covariates to estimate probabilities of occurrence in nearshore areas could help to strengthen these predictions. Mapping eelgrass distributions provides baseline data essential to eelgrass monitoring and implementation of coastal marine conservation, informing emergency response, and is particularly important considering the consequences associated with the potential loss of ecosystem functions in the event of eelgrass decline. King, B.G.C., Gullage, L., Butt, K., Warren, M., Allard, K., Gregory, R.S., and Byrne, M.A. 2026. Using shoreline characteristics, relative exposure, depth, and freshwater inputs as surrogate measures to identify areas potentially suitable for eelgrass (Zostera marina) in Newfoundland. Can. Tech. Rep. Fish. Aquat. Sci. 3737: vii + 22 p.https://doi.org/10.60825/7thp-4425

Eelgrass (Zostera marina) is important to waterfowl such as Atlantic Brant (Branta bernicla hrota), Canada Goose (Branta canadensis), American Black Duck (Anas rubripes), Common Goldeneye (Bucephala clangula) and Barrow's Goldeneye (Bucephala islandica). In New Brunswick eelgrass can be found along the Gulf of St. Lawrence, in protected harbours. Within this dataset are the results eelgrass land-cover classifications using either satellite or aerial photography for eight harbours: Bouctouche (46 30’N, 64 39’W); Cocagne (46.37 N, -64.60 W); Miscou (47.90 N, -64.55 W); Neguac (47.25 N, -65.03 W); Richibucto (46.70 N, -64.80 W); Saint-Simon (47.77 N, -64.76 W); Tabusintac (47.33 N, -64.93 W); and Tracadie (47.55 N, -64.88 W). Information on each dataset is provided:Visible orthorectified aerial photography was used to classify polygons containing eelgrass in Cocagne Harbour. Field data for image training and validation were collected along transects in summer 2008 using a dGPS positioned towfish holding sidescan sonar and a video camera that was later transcribed as XY geographic points to describe eelgrass presence and a qualitative description of density. The area was flown for photography on September 24, 2008. eCognition Developer 8 software was used to segment the imagery, essentially polygons. Polygons were then classified manually for the presence of eelgrass. Using field data revealed eelgrass presence to be mapped correctly 87.2% of the time.

Distribution of eelgrasses in coastal British Columbia showing relative abundance (RA) and overall relative importance (RI). RI is based on project region and not on the province as a whole. CRIMS is a legacy dataset of BC coastal resource data that was acquired in a systematic and synoptic manner from 1979 and was intermittently updated throughout the years. Resource information was collected in nine study areas using a peer-reviewed provincial Resource Information Standards Committee consisting of DFO Fishery Officers, First Nations, and other subject matter experts. There are currently no plans to update this legacy data.