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The Bigmouth Sculpin, Hemitripterus bolini, is a cottoid fish in the family Hemitripteridae found throughout the Bering Sea and Gulf of Alaska to British Columbia, Canada, and northern California. Hemitripterids have internal gametic association with external fertilization as their mode of reproduction. With this strategy, spermatozoa are stored in the micropyle of eggs within the ovary after gamete transfer to the female and eggs are not fertilized until immersed in seawater. Female H. bolini deposit their eggs into at least 4 species of sponges. We collected eggs from Barrel Sponge (Halichondria lambei), Clay-Pipe Sponge (Aphrocallistes vastus), Boot Sponge (Acanthascus dawsoni), and Tree Sponge (Mycale loveni) in the Gulf of Alaska and Bering Sea. In contrast to its congeners, there has been little research on H. bolini, particularly any focusing on aspects of early life history stages. In this study, we describe the development of H. bolini eggs and larvae from newly-hatched stages to juveniles, and include general observations of osteology. The descriptions of larvae and juveniles are based on examination of 32 specimens, 5 of which were differentially cleared and stained to examine osteological development. Larvae hatch at a large size (13 to 14 mm SL) in an advanced stage of development. Postflexion occurs at approximately 20 mm SL, and transformation to the juvenile stage begins at about 31 mm SL. Larvae are heavily pigmented through late flexion, when pigmentation becomes reduced. Postflexion larvae and juveniles are also heavily pigmented. Ossification of most skeletal elements does not occur until postflexion. The description will help distinguish H. bolini from other hemitripterids and sympatric larvae of the family Agonidae that are similar in appearance but generally smaller and more slender-bodied at all developmental stages. The behavior of egg deposition in sponges, in conjunction with the use of sponges by other fishes such as juvenile rockfish and invertebrates such as Golden King Crabs (Lithodes aequispina) as refuge habitat, suggests that sponge grounds may provide essential fish habitat for H. bolini and other species.
The basic ecology of torrent salamanders, family Rhyacotritonidae, is poorly known. This information lack is acute for the Columbia Torrent Salamander, Rhyacotriton kezeri, a species that is of conservation concern throughout its range. There have been no studies of its diet, which may be a significant barrier to its conservation and management. We studied the diet of both larval and post-metamorphic Columbia Torrent Salamanders in the Willapa Hills, Washington. A wide range of aquatic and terrestrial prey was documented, supporting both aquatic and terrestrial prey bases for this highly aquatic salamander. Copepoda and Diptera were particularly common in the diet of larvae, whereas Arachnida, Diptera, Collembola, and Coleoptera were more common in the diet of post-metamorphs. Our results for post-metamorphs were generally consistent with the diet of a post-metamorphic congener, R. variegatus, but demonstrate several new prey items for the family and some differences in frequencies of prey consumed.
We used avian point-count data collected from 4030 survey stations at Mount Rainier National Park, North Cascades National Park Complex, and Olympic National Park between 2001 and 2004 to describe observed elevation ranges of 74 bird species in the parks. Detailed elevation range information based on systematic sampling is essential for monitoring the effects of climate change on taxa whose ranges are likely to shift. Existing characterizations of the elevation ranges of Pacific Northwest birds are based primarily on anecdotal observations and professional opinion rather than systematic surveys. Here we analyze a systematically collected data set to describe the elevation ranges of common bird species in 3 large wilderness parks in Washington. These descriptions will facilitate future assessments of shifts in elevation ranges. More immediately, they will provide managers of more intensively managed lands outside the parks with reference information about elevational distributions of bird species from more-pristine park ecosystems.
We examined 14 wetlands in the Boreal Transition Zone (BTZ) of western Canada to investigate the effects of agricultural encroachment on aquatic macroinvertebrate communities and the response of waterfowl communities to these changes. The amount of agriculture within a 1.6-km buffer around wetlands was quantified primarily by remote imagery, and a sample of relatively similar wetlands was selected along an encroachment gradient from 0 to 90% agriculture. Species dominance showed temporal shifts during spring and summer. In May, 3 primary macroinvertebrate-dominated community types were present: 1) Amphipoda, 2) Diptera, and 3) Sigara. In August, 3 community types were present: 1) Amphipoda, 2) Notonecta, and 3) Chaoborus–Sigara. Environmental conditions were not distinct in every community type; however Sigara-dominated communities occurred in significantly shallower wetlands with greater concentrations of total inorganic nitrogen, total dissolved solids, and salinity than did Diptera dominated communities. Agricultural intensity was positively associated with phosphorus concentration. Phosphorus was likely an important factor in determining macroinvertebrate community composition with Sigara and Chaoborus–Sigara communities occurring in wetlands with very high concentrations of phosphorus (average >800 µg/L), and Diptera and Notonecta communities occurring in wetlands with lower phosphorus (average <160 µg/L). Amphipoda-dominated communities tended to occur in larger and deeper basins than Sigara-dominated communities. Waterfowl abundance was significantly and positively associated with macroinvertebrate abundance; however, occurrence of most waterfowl species did not correspond well with specific macroinvertebrate community types.
Bat gates are installed at the entrances of abandoned mines to protect bat habitat and ensure human safety; however, the response of bats to gates has received little study. Using mist nets and video surveys, we compared use of abandoned mines in northern Idaho by bats (species, entries, and behavior), before and after installation of bat gates, with bat use at ungated reference mines. The number of bat species using mines and the number of individual bats entering mines declined significantly at mines where gates were installed, but not at ungated mines. In addition, 3 of 7 behaviors recorded (entry looping, flying in front, and entry retreating) changed noticeably in frequency of occurrence at experimental mines after being gated, but these changes were not statistically significant. Our data suggest that, in the short-term, bat gates decreased the use of mines by bats and changed their behavior at the abandoned mines we studied. However, our results should be viewed cautiously, given our small sample sizes.
This study provides the first in depth assessment of Sea Otter haul-out patterns in Elkhorn Slough, California and their relationship to environmental variables. Seasonal and daily water and air temperature fluctuations are a good predictor of Sea Otter haul-out patterns but are affected by the availability of haul-out sites at different tide levels. The cost effectiveness of this choice may be maximal at night because of lack of human disturbance. Southern Sea Otters (Enhydra lutris nereis) were observed during 50 bimonthly 24-h periods between August 2007 and July 2009 (n = 1187 h) from a shore-based observation site located above a non-territorial male resting area on the north side of Moss Landing Harbor. We counted the number of Sea Otters in the area (both in the water and on land) at 30-min intervals. We also recorded tide height, and air and water temperature. Thirty-minute counts averaged 42 Sea Otters using the area (land and water) during the day and 66 at night. The average number of Sea Otters hauled out in the study area during the same haul-out event was 22, and the maximum number was 93. Sea Otters were observed hauled out on 70% of the days surveyed, and the proportion of Sea Otters hauled out was significantly higher at night. Higher numbers of Sea Otters on land was significantly correlated with lower air and water temperature, and with mid-range tide-heights. We speculate that haul-out behavior could play an important role in energy conservation; however, human-related traffic patterns in the area may negatively affect this energy conservation strategy.
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