Genetic Differentiation of English Sole in the Northeast Pacific Ocean and Salish Sea – Gary A. Winans, Jon Baker, Lyndal Johnson, Ingrid B. Spies, James E. West

The English sole (Parophrys vetulus, family Pleuronectidae) is an abundant ground fish used as a sentinel of marine pollution in the inland marine waters of Washington and Oregon. We use 15 microsatellite loci to evaluate patterns of genetic variability within and among 17 collections of sole from coastal sites and within the southern Salish Sea. Over 470 alleles were identified in 15 loci, and high levels of genetic richness, as estimated by expected heterozygosity (H_E) and allele richness (A_R), were detected. Fish sampled from coastal areas at the northern end of our study area had the lowest values of genetic richness, in contrast to collections at the southern end. The level of differentiation among all collections was low: mean F_ST value was 0.0006. Nineteen comparisons had statistically significant F_ST values (meanF_ST of 0.0029) and involved comparisons involving three locations associated with urban areas (Port Gardner [Everett, WA], Sinclair Inlet [Bremerton, WA] and Commencement Bay [Tacoma, WA]). A statistically significant, but weak, isolation by distance pattern (IBD) was seen in the five coastal collections over 1100 km of coastline. In contrast, in the Salish Sea collections, the pattern of differentiation was patchy and marked by several distinctive collections in close proximity to urban areas. The pattern of differentiation in the Salish Sea parallels differences seen in ecotoxicological characteristics of the English sole that inhabit separate urban embayments differing in pollution characteristics. Future work can focus on evaluating the stability and meaningfulness of this subtle variability in a time of local and global environmental changes.

Northwest Science 96: Accepted papers

Postglacial Fire and Vegetation History from Doheney Lake in the Sinlahekin Wildlife Area, Okanogan County, Washington (USA) – Megan K. Walsh, Kevin C. Haydon, Dale Swedberg

In recent decades, dry Pinus ponderosa-dominated forests of the eastern Cascades have experienced a dramatic increase in large, high-severity wildfires resulting in significant damage to natural resources. However, relatively little is known about long-term trends in postglacial fire activity in these forests. The purpose of this study was to reconstruct the fire and vegetation history of the Doheney Lake watershed, located in north-central Washington, using macroscopic charcoal and pollen analysis of a ca. 12,330 year-long lake sediment record. The results illustrate that regional climatic change, as well as climatically-controlled vegetation shifts, were the primary drivers of fire activity during much of the postglacial period. In particular, the establishment of the modern forest between ca. 7500-6000 cal yr BP due to cooler and moister conditions led to greater amounts of burnable biomass and generally higher levels of fire activity. The study results also suggest that greater interannual climate variability linked to drought may have played a role in the highly variable fire activity during much of the past ~6000 years. Additionally, it is likely that Indigenous cultural burning contributed to the fire activity at the site prior to Euro-American settlement, in particular during the past ~4000 years. Since ca. 125 cal yr BP (1825 CE), an almost complete absence of fire has allowed for the encroachment of shade-tolerant trees and has resulted in the potential for catastrophic wildfire, like that experienced at the site in 2015.

Influences of Succession and Biogeoclimate on Forage Resources for Elk in Northern Idaho – Deborah S. Monzingo, John G. Cook, Rachel C. Cook, Jon S. Horne, Lisa A. Shipley

Natural disturbance shaped forest communities for millennia, but fire suppression and timber harvest declines have altered forest structure across the western U.S., reducing the abundance of forage for ungulates. We evaluated quality and quantity of forage resources for lactating elk (Cervus canadensis) and their calves in relation to season, succession, and biogeoclimate, the latter indexed by potential vegetation (PV) zones, across 36,500 km² in Idaho’s Clearwater and St. Joe River Basins. In 0.2-ha macroplots (n = 359), we measured characteristics of forest overstory, biomass of current annual growth of undergrowth vegetation (kg/ha), and nutritional content of these plants. Using biomass, digestible energy (kJ/g), digestible protein (DP, g/100 g forage), and prior knowledge of elk diet selection and nutritional constraints, we developed eight forage resource metrics. The greatest abundance of undergrowth vegetation (500–1,000 kg/ha) occurred during the first 20 years after stand-replacing disturbance and declined as the overstory closed in wetter PV zones. Digestible energy decreased whereas DP increased as stands aged. Evidence of nutritional limitations for lactating elk increased markedly after mid-summer—early seral, high elevation spruce-fir forests on productive soils provided the best opportunity for lactating elk to satisfy their requirements in late summer. Our findings demonstrate the importance of disturbance regimes that maintain early seral communities in mosaics with mid- and late seral stages and suggest that implementing stand replacing disturbance in relatively moist forest zones at mid- and high elevations provides the greatest improvement in forage resources for lactating elk and their calves in summer. 

Drivers of Forested Riparian Microclimate on the Olympic Peninsula of Washington State – Katrina R. Keleher, Richard E. Bigley, Warren D. Devine

Riparian zones have unique microclimates that support distinct assemblages of aquatic and terrestrial species, which has resulted in a regulatory emphasis in recent decades on riparian protections. However, an understanding of the drivers of riparian microclimate in these protected riparian areas is still lacking. This study examined drivers of variability in summer air temperature and humidity in the riparian zones of ten drainage basins (31-789 ha) on the western Olympic Peninsula, Washington. Model selection analysis was used to explore hypotheses about the influences of three types of drivers on microclimate: regional climate gradients, proximity to stream, and solar radiation. Proximity to stream had the strongest influence on microclimate: the air became warmer and drier with increasing distance from the stream and with increasing steepness of the stream valley slope. Basins at higher elevations (28-362 m) had warmer, drier microclimates, a pattern attributed to greater coastal marine climate influence at lower elevations. Variation in microclimate also was associated with variation in solar exposure modeled as a function of topography. Testing of canopy closure influence on microclimate was hindered by the fact that canopy closure was uniformly high across the study area (87-98%) as a result of unmanaged, primarily second-growth stream buffers. Each of the microclimate drivers identified in this study was a function of topography, across a range of scales. By understanding these relationships between topographic variation and riparian microclimate, managers and researchers will be able to more accurately and efficiently delineate the extent of riparian microclimate influence.

Overwinter Mass Loss of Townsend’s Big-eared Bats in Five Caves – Jericho C. Whiting, Martha C. Wackenhut, Bill Doering

Quantifying overwinter mass loss in bats is important for understanding hibernation energetics, habitat conservation, and the ability of bats to persist with novel pathogens. Townsend’s big-eared bat (Corynorhinus townsendii) is a species of conservation concern. Little is known about overwinter mass loss of this bat in western North America. We conducted a retrospective analysis to quantify overwinter mass loss of 362 females and males during 1987 and 1988 in five caves in an important area for the conservation of this bat in western North America. Although body mass of 13 females in cave C62 averaged 1.1 g heavier than 12 females in cave C54 when captured in October, all those females recaptured in March lost similar percentages of body mass  ( = 22.7%) over winter. In cave C27, body mass of six females averaged 2.6 g heavier than eight males when captured in October. Those recaptured females and males in March lost similar percentages of body mass ( = 19.5%) over winter. In caves C27 and C54, mass of 96 male bats decreased by a mean of 21% between October and March. In five caves, mass of 227 female bats decreased by a mean of 23.4% between October and March. Our results indicate that females are heavier than males when entering hibernation, and that females generally lose more mass than males during hibernation. Moreover, female bats entering hibernation in our study area weighed more than female bats of this species in other studies when entering hibernation. Our data provide researchers in western North America with mass loss estimates for female and male Townsend’s big-eared bats. 

Influence of Above-Ground Pipeline and Associated Factors on Movement of Winter Active Boreal Mammals in the Alberta In-Situ Oil Sands – Michael L. Charlebois, Hans G. Skatter, Sondre Skatter, John L. Kansas

Above-ground pipelines (AGP) associated with in-situ oil sands may restrict mammal movement potentially increasing extinction probability and decreased reproductive success. Our 12-year study used winter track count techniques to assess the response of winter-active mammals to AGP in northern Alberta, Canada. The primary questions were: Which species were most prone to movement obstruction by AGP, facilities or natural factor(s) and which factor exerted the strongest influence on crossing likelihood. 

A total of 2,068 trails of 12 different species were observed. All species crossed more than half of the time. Focal species crossed on average eighty percent of the time. Crossing likelihood of white-tailed deer (Odocoileus virginianus), ermine (Mustela erminea), coyote (Canis latrans), lynx (Lynx canadensis), and fisher (Martes pennanti) were significantly influenced by predictors including pipeline height, pipeline corridor width, infrastructure age, vegetation type, and proximity to infrastructure. Deer and lynx crossing likelihood was positively affected by pipe height. Deer, coyote and ermine crossing likelihood was positively affected by age of pipe. Fisher and deer crossing likelihood was negatively affected by pipeline corridor widths. Our investigations show that most species cross AGP with high crossing frequencies of pipe heights ranging from 130 cm to 160 cm.  

These findings are important for impact mitigation because: the scarcity of published studies of wildlife movement responses to AGP, our inclusion of small and mid-sized carnivores, and, our investigation of multiple factors.

We highlight mitigation/design improvements, effects of pipeline corridor widths, and challenges posed by coupling infrastructure with pipelines, serving to reduce movement barriers/fragmentation.

Cascadia Clues to a 1700 Earthquake as Documented in the 1800s – Brian F. Atwater, David K. Yamaguchi, Jessie K. Pearl

Northwest newcomers of the nineteenth century recorded ecological anomalies later ascribed to a Cascadia earthquake. The most salient were subfossil trees in brackish tidelands. James Graham Cooper, as a naturalist attached to the Smithsonian Institution in the 1850s, called attention to western redcedar standing dead in tidal marshes of Shoalwater Bay (modern Willapa Bay). Two such redcedar served as bearing trees for John J. Lowell, then subdividing a Shoalwater Bay township under contract with the General Land Office. Cleveland Rockwell, mapping tidal shores west of Astoria for the United States Coast Survey in 1868, fringed them with radiating symbols that evoke sprawling spruce stumps. Today, redcedar trunks and spruce stumps in these and other tidelands serve as evidence for lowering of coastal land during a Cascadia earthquake in 1700. Since that earthquake, sedimentation and gradual uplift have enabled post-earthquake succession from tidal flat through tidal marsh to new tidal forest. This post-1700 succession had reached an intermediate stage in 1805 at a Columbia River tidal marsh that Meriwether Lewis called a “marsey prairie.” Post-1700 succession in nearby freshwater tidal forests may have influenced Lewis’s division of Sitka spruce into massive upland old growth and smaller tideland trees. These assorted field observations make sense today by analogy with forest death and renewal near Anchorage that the 1964 Alaska earthquake occasioned.

Comparative Phylogeography of Microsnails from the Pacific Northwest – Megan L. Smith, Connor Lang, David Sneddon, Jessica Wallace, Anahí Espíndola, Jack Sullivan, Bryan C. Carstens

Leaf-litter dwelling invertebrates serve an important role in ecosystem function by breaking down nutrients and potentially acting as indicators of habitat quality. However, this community is understudied due to difficulties related to sampling and taxonomic identification. To explore this community, we sampled leaf litter from the Coastal and Cascades ranges of the Pacific Northwest of North America (PNW) and searched > 200 samples for micro-invertebrates. We removed and photographed more than 400 invertebrate specimens, sequenced a portion of the mitochondrial gene cytochrome oxidase I (COI) for 60 samples, and used COI and the BLASTn database to identify invertebrates. Using these sequences and environmental data from the collection localities, we investigated the phylogeographic history of the two best-sampled species of microsnails, Columella edentula (toothless column snail) and Punctum randolphii (conical spot snail). Results suggest that populations of these species from the Coastal and Cascades ranges may have survived in a single refugium during the Pleistocene glacial cycles and recolonized the Coastal and Cascades ranges during the Holocene. Our results add to the knowledge of species responses to the Pleistocene glacial cycles in the PNW and suggest that future studies should aim to increase representation of micro-invertebrates, perhaps using metabarcoding techniques.

Implications of Metrics and Methodology for Juvenile Salmonid Monitoring in Western Oregon Streams – Ronald J. Constable Jr., Erik Suring

We attempted to determine whether electrofishing removal estimates or single pass snorkeling was a more reliable method for Oregon Department of Fish and Wildlife (ODFW) monitoring of juvenile coho salmon (Oncorhynchus kisutch) and steelhead (O. mykiss) abundance and occupancy trends. Based on 1997–2000 data we assumed abundance estimates from the method that tracked more closely with parental abundance would better approximate true juvenile abundance. Parental abundance from spawning ground surveys and juvenile abundance metrics unique to each method were estimated from 2000–2004 and 2007–2008. Parental abundance did not explain the variation in juvenile abundance from either method (r² < 0.22), invalidating our assumption, but results had relevance for snorkel surveys used in ODFW monitoring. For both species, correlations between density (fish/m²) and abundance (quantity, based on fish/km) estimates from snorkeling were weak (r < 0.379) but correlations between abundance estimates from both methods were strong (r > 0.846); implying abundance was more appropriate than density for ODFW monitoring. Neither method could sample all habitats, and annually variable proportions of coho salmon (15–47%) and steelhead (0–24%) abundance estimates obtained by electrofishing were in pools too shallow to meet the ODFW depth criterion for snorkeling. This resulted in lowering the criterion to ≥ 20 cm in 2010. The lower criterion, relative to original, has not shown differences in trends but 30% more pools have been sampled, resulting in 23% higher abundance estimates with 10% proportionately smaller confidence intervals. These changes improved ODFW monitoring and related management decisions.

Three-year Effects of Crown Removal by Clipping or Burning on Beargrass (Xerophyllum tenax) Size and Biomass – David H. Peter, Timothy B. Harrington

Beargrass (Xerophyllum tenax [Pursh] Nutt.), an evergreen perennial herb of the northern Rocky Mountains, Pacific Northwest and northern California, is used in Native American basketry and commercial floral greens. We studied beargrass size and biomass responses to crown removal by clipping or burning over three years in a coast Douglas-fir (Pseudotsuga menziesii var. menziesii) woodland having variable shrub cover in the southeastern Olympic Peninsula of Washington State. Clipping forested plants resulted in 28% mortality, mostly from smaller plants growing under 26% more total cover than the surviving plants; however, only 3% of completely crown scorched open grown plants died. Three years after treatment, crown width of surviving plants was only 61% of the pre-treatment size for clipped plants compared to 88% for completely crown scorched plants. Regression analyses indicated that the percentage of crown scorch accounted for only 16% and 27% of crown width and foliar height variation, respectively, one year post-burn, decreasing to 10% and 19% at three years post-burn. During the three years after burning, percentage flowering increased linearly to 64% of plants. Three years post-burn foliar browse was higher on crown scorched than on non-crown scorched plants. Although shade tolerant, long-term survival of lowland beargrass is likely limited by combined competition from shrubs and trees. Stand density management is needed to maintain healthy, reproducing populations in the lowlands of western Washington.