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Three new species of Navicula sensu stricto are described from samples deposited in the Montana Diatom Collection. Navicula galloae and N. sovereignii live in streams in the Cascade Mountains of Oregon. N. flatheadensis lives in lakes in the headwaters of the Flathead River Basin in western Montana. At present, 80 species and varieties of endemic diatoms in 20 genera define the Northwest as a distinct biogeographical region, and many endemic species remain to be described. Other diatom taxa in the region indicate floristic affinities with northeast Asian, Arctic, and European alpine floras. Factors contributing to the large number of endemic taxa and to observed floristic affinities are discussed.
The ability to predict patterns of species dispersal across habitat edges takes on increasing conservation relevance as land-scapes become more fragmented. We assessed edge responses for four ground-dwelling arthropod taxa by measuring their distribution and movement patterns across a forest edge associated with a forested riparian buffer and an adjacent upslope clearcut at a single site. We used Spatial Analysis by Distance Indices to describe the spatial distribution of arthropods, habitat variables, and the associations between them across a 49 × 63 m pitfall trapping grid with 80 trapping stations. We used mark-release-recapture techniques to measure the distance, rate, and direction of arthropod movement within and between habitat types. Scaphinotus angusticollis (Coleoptera; Carabidae) was restricted to the cool, moist portion of the riparian buffer and was not observed to cross the forest edge. The carabids Pterostichus lattini and Scaphinotus marginatus had more eurytopic distributions across all habitats. Higher overall mobility for S. marginatus may explain, in part, the greater frequency of movement for this species across the forest/clearcut edge. Lycosid spiders, strongly associated with the clearcut, also moved into one portion of the riparian buffer that was warmer and drier. They had a relatively high frequency of movement across the clearcut/forest boundary. These results suggest that ground-dwelling arthropod taxa are likely to respond differently to habitat edges, and that their habitat affinities and mobility strongly influence movement patterns across the landscape. Understanding these patterns of distribution and movement will aid the sustainable management of forest and riparian arthropod taxa in fragmented landscapes.
We used both on-shore holding and field releases of wild fish to evaluate the effect of using intracoelomic surgical implantation of small radio transmitters (4 g, 9.5 mm diameter, 26 mm length) on adult mountain whitefish. In the holding study, all fish survived the 48 hr period following surgery. Significant mortalities were noted on days four and five of the experiment; however, tagged fish were no more likely to die than control fish. Incisions showed signs of healing and had no macroscopic inflammation. The times until exhaustion during forced swimming trials were similar between tagged and control fish. However, after fish were held for five days, exploratory activity levels were depressed in both groups, emphasizing the potential consequences of retaining this species for even short periods of time. When we implanted twelve mountain whitefish with tags (0.7–3.0% of body weight) and released them in the Columbia River, we had reasonable success at tracking movements of these fish over three seasons and there was no evidence of tagging mortality after release. We suggest that using the protocols described here, it is possible to implant adult mountain whitefish with electronic tags but advise that fish should not be held for more than several hours post-implantation to minimize stresses of handling and captivity. This finding is consistent with the growing body of literature suggesting that pre- and post-surgical care is an important component of successful transmitter implantation.
Industrial timber harvesting typically creates forest edges with altered microclimate regimes, causing reduced growth and survival of some canopy epiphytes. This process has implications for the marbled murrelet (Brachyramphus marmoratus), a threatened seabird that nests on moss platforms in old-growth forests of the coastal Pacific Northwest in North America. We investigated microclimate and epiphyte availability in old-growth forests of southwestern British Columbia, Canada. We contrasted mean and maximum temperature, mean humidity, mean vapor pressure deficit (VPD) and mean epiphyte cover and platform tree density between forest edge and interior plots at hard edges (recent clearcuts), soft edges (regenerating forest) and natural edges (rivers and avalanche chutes). Differences measured in VPD and epiphyte availability varied due to edge proximity and edge-type. Hard edges had fewer trees with suitable marbled murrelet nest platforms relative to adjacent interiors, and hard-edged patches had the lowest epiphyte cover overall. This suggests that microclimate edge effects and substrate availability can negatively impact epiphyte growth and survival, and may reduce the availability of marbled murrelet nest sites. These negative effects may decrease with time as forests regenerate, as edge effects were lower in magnitude at soft-edged patches. In contrast, natural-edged patches had the greatest levels of epiphyte cover and platform tree density, suggesting that these areas provide an abundant source of potential nest sites. Minimizing the ratio of anthropogenic edge to suitable interior habitat, and maintaining natural edges will limit negative edge effects on moss availability and provide nesting habitat for marbled murrelets.
We implanted 2212 juvenile coho salmon (Oncorhynchus kisutch) 55 to 111 mm with Passive Integrated Transponder (PIT) tags to determine their growth, overwinter survival, and emigration timing from the East Twin River and its tributary, Sadie Creek, on Washington's Olympic Peninsula. Detections of tagged fish by instream antennas revealed that a much higher proportion of juvenile coho salmon emigrated to the sea in the fall than during the spring. Fall emigrants predominantly originated from East Twin River (96.6%) whereas Sadie Creek coho salmon remained in-stream to overwinter where they grew faster and became larger when compared to smolts from East Twin River. Results suggest that fish size in the fall and location in the watershed may influence emigration timing.