Distribution of Potentially Harmful Phytoplankton Species in the Northern Strait of Georgia, British Columbia

Abstract

Spatial and temporal distributions of Chaetoceros convolutum (including C. concavicorne), Heterosigma akashiwo, Protogonyaulax (= Alexandrium) catenella, and Dinophysis are presented for the northern Strait of Georgia from March to September, 1986. In spring C. convolutum was found on the slightly stratified eastern side in concentrations just below those leading to kills of caged salmon (4-5000 cells∙L−1). The northern Strait became thermally stratified in summer. At this time the population centre of C. convolutum shifted to mid-Strait near the edge of the Discovery Passage tidal jet where it was maintained near the pycnocline (10–15 m) in concentrations up to 35,000 cells∙L−1. Heterosigma akashiwo, another fish killer, was the pbotosynthetic dominant in June and reached 200 000 cells∙L−1 in the northwest at 5 m. Protogonyaulax catenella, a source of paralytic shellfish poison (PSP), was also most abundant in the north and west, where dangerous levels of PSP often occur, particularly near Comox. Collectively, Dinophysis species exceeded the critical concentration for diarrheic shellfish poisoning (200 cells∙L−) on the western side during summer. All the potentially harmful flagellated species seem to be introduced from the northern passageways. Sheltered bays to the north are possible seed beds for cyst-forming species whereas C. convolutum remains in the Strait year-round.

Diarrhetic shellfish poisoning (DSP) associated with a sub-surface bloom of Dinophysis norvegica in Bedford Basin, eastern Canada

“…It should be pointed out that Lee et al (1989) reported the presence of both OA and DTX-1 in a sample of Dinophysis norvegica, while another sample of this species collected from Norway during the same month contained only DTX-1. There were other instances (Haamer et al 1990) in which DSP toxins were apparently low in the samples containing high proportions of D. norvegica in excess of the critical concentration (200 cells I-') for DSP (Haigh & Taylor 1990). This was also true in our samples.…”

Mosaicism of microplankton communities in the northern Strait of Georgia, British Columbia

“…The photosynthetic dominant in June was Heterosigma akashiwo, which was abundant throughout the Strait at all depths sampled (Haigh and Taylor 1990). Highest abundance in the northwest suggests that growth of H. akashiwo was enhanced by the nutrient pump effect of the plume and/or that it was injected from the northern passages.…”

Harmful Algal Blooms: Physiology, Behavior, Population Dynamics and Global Impacts- A Review

“…Diatoms are often implicated in such events (Bell, 1961;Taylor et al 1985;Farrington, 1988;Rensel, 1993;Kent et al 1995;Tester and Mahoney, 1995). The raphidophyte Heterosigma akashiwo presents a serious problem for aquaculture in many parts of the world including Japan, North America, Asia and New Zealand (Haigh and Taylor, 1990;Change et al 1990;Black et al 1991;Mackenzie, 1991;Qi et al 1993;Honjo, 1994). Affected salmon shows signs of gill and intestinal pathology and death has been attributed to impairment of the gills' respiratory and osmoregulatory functions (Change et al 1990).…”