Seasonal Seaweed Diversity in the Intertidal Zone of Greater Vancouver

This dataset is derived from transect surveys performed in the intertidal zone of four sites in the Greater Vancouver area of British Columbia: Brockton Point, Vancouver; Lighthouse Park, West Vancouver; Crescent Beach, Surrey; and Cates Park, North Vancouver. Each site was surveyed in July 2022, November 2022, and February 2023. For each survey four vertical transect lines were laid out from the high intertidal to the tideline during low tide, and quadrats were laid down every 5 m. Tidal height for each quadrat was determined with a surveyor’s level and substrate type within each quadrat was recorded. Percent cover of each visually distinct macroalgal or seagrass species was estimated within each quadrat; for species that could not be identified in the field, representative vouchers were collected and analysed in the lab using a dichotomous key or DNA barcoding. Pressed vouchers were assigned a collection number and deposited at the University of British Columbia Herbarium. Unique species that were not otherwise observed within quadrats were also recorded as present "out of quadrat". A combination of tidal height, landmarks, and extensive site/quadrat pictures was used to ensure that quadrats were placed in the same spot during each of the three surveys at a given site. The goal of this project is to establish a baseline in the seasonality of different macroalgal/seagrass species at different sites with respect to both abundance and distribution on the shore, in anticipation of potential shifts in community structure related to future changes in climate and land use. It was funded via the Department of Fisheries and Oceans Canada's Coastal Environmental Baseline Program under the Oceans Protection Plan, as well as a grant from Langara College's Applied Research Centre.