Strait of Georgia Biodiversity in Relation to Bull Kelp Abundance

Pacific Marine Life Surveys Incorporated (PMLS) has a unique database for Pacific Northwest marine life that includes seaweed identifications from 1983 on. Included in this database is dive log data for the Strait of Georgia, comprising some 3,137 dives in 358 sites. The data span a time period from 1967 to present. The logs contain all the species observed with a total of 1,097 algal and animal species from all major phyla.

Through a competitive bidding process and assessment of their capabilities, the firm was chosen by the Pacific Fisheries Resource Conservation Council to undertake the study leading to this report as a contribution to improved understanding of marine ecosystems and impacts on wild Pacific salmon and other species.

The presence of bull kelp Nereocystis was recorded in moderate to strong abundances in most regions for at least part of the time periods of observation, with three exceptions:

Lambert/Nanoose, Sunshine, and Howe Sound, all of which are in the middle latitudes of the greater Strait of Georgia area. Significant presence of sea urchins Strongylocentrotus occurred throughout all regions of the Strait of Georgia. Urchins, a known grazer of seaweeds, are abundant throughout the entire study area, but a few sites within the Howe Sound and Lambert Channel regions feature urchin barrens: where no seaweeds occur. It is not possible to determine why bull kelp is less abundant near the middle of the Strait of Georgia because the absence of bull kelp does not correspond to any significant shifts in ecosystem biodiversity. Instead, the seabed biodiversity of the Strait of Georgia is remarkably stable and extensive throughout the region, regardless of bull kelp presence.