Abstract
Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage.
Highlights
Marine biodiversity in Canada’s oceans can be assessed in several ways, each with its own attributes, limitations, and applications
The Oceans Act in Canada recognizes that three oceans—the Arctic, the Pacific, and the Atlantic—are the common heritage of all Canadians
This Act holds that conservation based on an ecosystem approach is of fundamental importance to maintaining biological diversity and productivity in the marine environment
Summary
Marine biodiversity in Canada’s oceans can be assessed in several ways, each with its own attributes, limitations, and applications. The first extensive report on phytoplankton was published [88] on waters west of Greenland, including some eastern Canadian Arctic regions They reported a total of 89 phytoplankton species, mostly represented by large cells belonging to diatoms (48 taxa) and dinoflagellates (37 taxa). Many of the changes in zooplankton diversity noted in the last several decades are attributable partly to increases in geographical coverage and depth range of collections, partly to poleward zoogeographic range extensions that have accompanied recent climate fluctuations and trends ( in Western Canada), and partly to recent taxonomic revisions (often including splits at the genus or species level) and the use of more complete keys in identification of routine survey samples. Marine zooplankton from Eastern Canada coastal waters include members of eight phyla (Cnidaria, Ctenophora, Mollusca, Annelida, Arthropoda, Chateognatha, Echinodermata, and Chordata) with a total of 381 identified species (Table S1). These survey efforts might instead enhance diversity by revealing range extensions of Arctic species to the south, or of temperate and subarctic species to the north
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