A coupled biophysical model of the Strait of Georgia (SoG), British Columbia, Canada, has been developed and successfully predicts the timing of the spring phytoplankton bloom. The physical model is a one-dimensional vertical mixing model, using a K-profile parametrization of the boundary layer, forced with high frequency meteorological data. The biological model includes one phytoplankton class (microphytoplankton) and one nutrient source (nitrate). The spring bloom in the SoG occurs when phytoplankton receive enough light that their growth rates exceed their loss rates. The amount of light that the phytoplankton receive is a function of solar radiation and the depth of mixing. The model was used to determine what physical factors are controlling the phytoplankton losses and the light received by the phytoplankton. Wind was found to control the spring bloom arrival time, with strong winds increasing the mixing-layer depth and delaying the bloom. The amount of incoming solar irradiance, through amount of cloud cover, had a secondary effect. The freshwater input (primarily Fraser River discharge) had an insignificant effect on the timing. Increased freshwater flux increases the buoyancy flux and thus decreases the mixing-layer depth but also increases the strength of the estuarine circulation, increasing the advective loss.

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The differences in geographical distribution between Anguilla reinhardtii and A. australis on the eastern coast of Australia can be understood by comparing otolith growth increments and microchemistry, the ages between species of the eels at metamorphosis from leptocephalus to glass eels and the ages of glass eels at estuarine arrival. The ages at metamorphosis were determined from where the increment width dramatically increased and the Sr/Ca ratio dropped. The mean age (± s.d.) of A. reinhardtii (n = 176) at metamorphosis was 144.5 ± 12.2 days and at estuarine arrival was182.7 ± 16.3 days. For A. australis (n = 150) it was 173.7 ± 20.5 days and 229.2 ± 29.4 days, respectively. The differences in age between species were significantly larger than the annual and seasonal variations within species. Australian eels are believed to spawn in the tropical oceans and larval eels drift in the South Equatorial Current to eastern Australia. The younger ages at estuarine arrival of A. reinhardtii suggest that the spawning grounds of this species lie closer to Australia than those of A. australis. In addition, the mean total length at recruitment of A. reinhardtii (49.9 ± 2.0 mm) was significantly smaller than for A. australis (54.6 ± 5.4 mm) (t = 3.8, P < 0.01). However, the growth rates of A. reinhardtii (0.25 ± 0.02 mm/d) were significantly faster than for A. australis (0.23 ± 0.022 mm/d)(t = 7.6, P < 0.01). The smaller sizes of A. reinhardtii at recruitment were likely due to the shorter marine larval period and faster growth rate compared with A. australis. The duration of the marine larval period and growth rate may be the principal factors in determining the geographical distribution of both A. reinhardtii, which tend to occur in tropical-subtropical waters, and A. australis, which predominate in more temperate waters.