The Canadian Field-Naturalist (E-Journal)
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Diet of a rare Canadian fish species, Carmine Shiner (Notropis percobromus) in the Birch River, Manitoba, Canada
Get PDFDue to its restricted occurrence and existing threats, Carmine Shiner (Notropis percobromus) has been listed as threatened under the Canadian Species at Risk Act. Little is known about Carmine Shiner biology, and understanding its diet composition will help inform future conservation actions. Consequently, the aim of this study was to analyze the diet of Carmine Shiner. Fish were caught throughout the open water season using beach seines, and stomach contents were analyzed. Carmine Shiner feed on a variety of terrestrial and aquatic insects. Diets did not differ substantially between year classes, and we observed no clear temporal trends in diet composition
No relationship between gastrointestinal parasite intensities or mercury burdens on fluctuating asymmetry in Common Eider (Somateria mollissima) mandibles
Get PDFMercury (Hg) emissions have increased since 1950 and biomagnification in Arctic ecosystems can affect animals, particularly at higher trophic levels. Exposure to Hg can negatively affect young developing animals, resulting in altered morphology and ultimately, lower fitness. We examined the relationship of mandible fluctuating asymmetry (FA) with gastrointestinal helminth intensity and breast muscle Hg concentration in Common Eider (Somateria mollissima borealis). Procrustes analysis of variance indicated significant FA but relatively high measurement error. Based on multiple linear regression modelling, there was no significant relationship between FA and Hg concentration or parasite burden. There may be a mismatch in trying to relate amount of Hg and parasite intensity in adults to FA that would have occurred early in life during skeletal development
Reductions in foliar Hemiptera in portions of a fescue grassland invaded by Smooth Brome (Bromus inermis)
Get PDFFescue grassland in Canadian prairie is characterized by Plains Rough Fescue (Festuca hallii), but the introduced exotic grass, Smooth Brome (Bromus inermis), is expanding therein. Hemiptera play an important role as herbivores in vegetation. In an invaded fescue grassland in Manitoba, 52 plant species had a combined average cover of 216%. Kentucky Bluegrass (Poa pratensis), another exotic grass, was most abundant at 64%, followed by B. inermis at 21% and the native grass F. hallii at 18%. Across 47 random sample points, B. inermis cover ranged from 0% to 180%. At these points, 2445 specimens of Hemiptera were collected by sweep net and divided into 99 morphologically distinct species. Bromus inermis cover had negative correlations with Hemiptera species richness and diversity, but not with abundance and biomass of Hemiptera. However, B. inermis cover was negatively correlated with abundance of two individual species of Hemipteran leafhoppers in the family Cicadellidae: Doratura stylata and Diplocolenus configuratus. Total graminoid cover had no significant correlation with any of the above Hemiptera variables. We conclude that feeding requirements deter some phytophagous Hemiptera from entering sections of fescue grassland invaded by B. inermis. In this way, invasion by B. inermis can be expected to modify ecosystem function by increasing feeding pressure on neighbouring natural vegetation and other introduced species
An update to the distribution of the Endangered False Hop Sedge (Carex lupuliformis Sartwell ex Dewey; Cyperaceae) in Ontario
Get PDFWe provide an update to the Ontario distribution of False Hop Sedge (Carex lupuliformis), prompted by the first documented report of the species in the Niagara region, which represents a noteworthy eastern range extension in the province.
Distribution and status of Howell’s Quillwort (Isoetes howellii, Isoetaceae) in Canada and its relation to Bolander’s Quillwort (Isoetes bolanderi)
Get PDFThe sparsely documented lycophyte, Howell’s Quillwort (Isoetes howellii), occurs in Canada in four distinct areas of British Columbia in a variety of microhabitats. Before 2010, two areas of occurrence were known in Canada. Two additional clusters of occurrences have been discovered in the last decade. In Canada, I. howellii is found in open, ephemeral wet swales, shallow ponds, and periodically flooded shorelines, channels, and back beach meadows. Habitat rarity may be the primary reason for the large gaps between areas of occurrence. The current viability of the Canadian population is dependent on maintaining the recently discovered large number of individuals in the North Thompson River Region. Isoetes howellii shares many similarities with fellow diploid, Bolander’s Quillwort (Isoetes bolanderi). The possibility that it represents a low-elevation subspecies of I. bolanderi requires further investigation. Isoetes howellii is rare in British Columbia and warrants consideration as a species at risk in Canada
