. The Canadian field-naturalist. Natural history; Sciences naturelles. w â * .^fc^' h^v:^v- ' Figure 2. Photograph of a hypersaline spring containing extensive mats of P. percursa. A 15 cm tent peg inserted beside the spring is included for scale. near Lake Winnipegosis, it was by far the dominant organism, associated with various pennate diatoms and cyanobacteria (including members of the Oscil- latoriaceae) (unpublished data) but not other filamen- tous green algae. Habitat and distribution There are numerous saline springs along the western shore of Lake Winnipegosis (Grasby 2000; Bezys et
. The Canadian field-naturalist. Natural history; Sciences naturelles. w â * .^fc^' h^v:^v- ' Figure 2. Photograph of a hypersaline spring containing extensive mats of P. percursa. A 15 cm tent peg inserted beside the spring is included for scale. near Lake Winnipegosis, it was by far the dominant organism, associated with various pennate diatoms and cyanobacteria (including members of the Oscil- latoriaceae) (unpublished data) but not other filamen- tous green algae. Habitat and distribution There are numerous saline springs along the western shore of Lake Winnipegosis (Grasby 2000; Bezys et al. 1997; McKillop et al. 1992) as well as in north-eastern Alberta (Grasby and Chen 2005), however, prolific growth of P. percursa has only been confirmed at the Dawson Bay salt springs located on the north-western shore of the lake. Similar algal growths have been observed at other sites west of Pelican Bay and south of Red Deer River, but detailed analyses have not been done to confirm P. percursa. Salinity at these sites is typically greater than that of the springs located fur- ther south in Manitoba, and this may explain the dom- inance of P. percursa. The salinity of the springs is thought to be increasing over time (Patterson et al. 1997), and although the full range salinity tolerance is unknown, it does not seem to be limiting growth of this organism, but rather promoting it. P. percursa can grow in diluted seawater over a range of 0-34 PSU (practical salinity units), with an optimum of 24 PSU (Taylor et al. 2001), but tolerance above seawater has not been tested. P. percursa has a broad tolerance to environmental conditions of irradiance (9-175 umol m2 s1) and temperature (at least 10-30°C), as well as k. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa, O
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