Review of the Biological Oceanography of the Strait of Georgia: Pelagic Environment

Abstract

Different components of the food web in the Strait of Georgia are reviewed. The phytoplankton are dominated by diatoms; however, flagellates may dominate in the winter. Chlorophyll a concentrations may range from < 1 mg∙m−3 in the winter to > 15 mg∙m−3 during blooms. The average annual primary productivity is about 280 g C∙m−2 for the strait, but it is higher in frontal areas at the north and south ends of the strait and near the Fraser River plume. Light limits primary productivity during the winter months, while nutrients (nitrogen) and grazing are the limiting factors during the late spring and summer. Turbidity and salinity effects occur near the Fraser River plume. The surface macrozooplankton community is composed chiefly of copepods. Mid- and deep-water communities consist of euphausiids, chaetognaths, and some deep-living copepods, which overwinter at depth. The standing stock of macrozooplankton (> 350 μm) to 400 m, ranges from 0.1 to 2.0 g wet wt∙m−3. Few estimates of secondary production and standing stock estimates of microzooplankton have been made. Horizontal patches of zooplankton have been encountered and may be important feeding sites for some fish. Standing stock associations of the dominant species in the food web of the strait are reasonably well known, but assessment of food web dynamics from these limited standing stock measurements is often inaccurate. There is a noticeable absence of data on how rate processes affect standing stocks, and it is particularly an understanding of these interrelationships that is needed for fisheries management. There is an urgent need for more interaction between biological oceanographers and fisheries scientists, particularly in the area of zooplankton grazing by larval fish.

The sensitivity of estuarine aragonite saturation state and pH to the carbonate chemistry of a freshet-dominated river

“…The seasonal progression of productivity in the Strait of Georgia begins with a characteristic spring phytoplankton bloom (Allen and Wolfe, 2013) followed by a shallow (∼ 20 m) surface layer of productivity throughout the summer that transitions into weaker fall blooms before returning to the background winter state (Harrison et al, 1983). Below this productive surface layer, the DIC-rich intermediate basin is persistently aragonite undersaturated.…”

Distribution and Cycling of Suspended Particles Inferred from Transmissivity in the Strait of Georgia, Haro Strait and Juan de Fuca Strait

“…In the Strait of Georgia, turbid plumes from the Fraser and Squamish rivers limit productivity by reducing the penetration of light into the water column, although productivity is high at the edges of the Fraser River plume, due the high nutrient concentration (Harrison et al, 1983). A high surface concentration of CDOM, which would be transparent to the transmissometer because CDOM does not absorb measurably at 660 nm, would also reduce the potential for primary production by absorbing some of the short wavelength radiation used by phytoplankton.…”

Harmful algal blooms and red tide problems on the U.S. west coast

“…However, successional patterns may be interrupted by periods of episodic upwelling, which result in a return to diatom-dominated assemblages (Garrison 1979). Farther north, in estuarine areas of the Strait of Georgia, diatoms are present in spring and summer; dinoflagellates are most abundant in summer, but may be present also in spring and winter; and autotrophic flagellates are common in late summer or winter in some inlets (Harrison et al 1983). Ship-based sampling and remote-sensing techniques suggest phytoplankton blooms are most highly developed in shallow regions of the continental shelf (e.g.…”