Many of the exotic species in the Canada’s Pacific marine ecosystem has been related to the introduction and maintenance of Japanese and Atlantic oysters for commercial production. However, the varnish clam (Nuttallia obscurata) is believed to have arrived in the Strait of Georgia region in ballast water in the late 1980s.
ES 11 ran four transects of 50 cm square quadrat plots at .5 m elevation intervals from 1996 to 2001 at Cherry Point on Vancouver Island. The classes kept records of bivalves between 0 and 10 cm depth and to 30 cm depth across a specific cobble/pebble/sand/mud beach. Throughout this survey period, specific attention was given to populations of varnish clams. The substrate was shoveled through a seive, washed and clams were identified and each species counted. The survey began in October 1996 and was conducted Oct 2000.
Results of the surveys: Populations of clams generally decreased in the higher quadrat plots. Only Varnish Clams were found at 2.5 m above 0 tide. Increasing populations were found in the lower quadrat plots. In October 1996 many native species (10 to 55 in total in each plot) were found at 1.5, 1, and .5 meter plots along all four parallel transects. At this time zero to 3 varnish clams were found in the quadrat plots throughout the survey area. By 2000 students were finding as many as 100 varnish clams in some of the quadrat plots while populations of native clams diminished to single digits.
The Canadian Department of Fisheries and Oceans shares an interest in monitoring populations of invasives and have been helpful in defining appropriate protocols for schools. Bill Austin with the Cowitchin Bay Marine Ecology Station spearheaded the research project along with Bob Sharp. The chart below shows the sum of clams found in all four transects.
ES 11 ran four transects of 50 cm square quadrat plots at .5 m elevation intervals from 1996 to 2001 at Cherry Point on Vancouver Island. The classes kept records of bivalves between 0 and 10 cm depth and to 30 cm depth across a specific cobble/pebble/sand/mud beach. Throughout this survey period, specific attention was given to populations of varnish clams. The substrate was shoveled through a seive, washed and clams were identified and each species counted. The survey began in October 1996 and was conducted Oct 2000.
Results of the surveys: Populations of clams generally decreased in the higher quadrat plots. Only Varnish Clams were found at 2.5 m above 0 tide. Increasing populations were found in the lower quadrat plots. In October 1996 many native species (10 to 55 in total in each plot) were found at 1.5, 1, and .5 meter plots along all four parallel transects. At this time zero to 3 varnish clams were found in the quadrat plots throughout the survey area. By 2000 students were finding as many as 100 varnish clams in some of the quadrat plots while populations of native clams diminished to single digits.
The Canadian Department of Fisheries and Oceans shares an interest in monitoring populations of invasives and have been helpful in defining appropriate protocols for schools. Bill Austin with the Cowitchin Bay Marine Ecology Station spearheaded the research project along with Bob Sharp. The chart below shows the sum of clams found in all four transects.