Arnold Winfred Reitze, Jr. / George Washington University, School of Law

In the past, sharks, skates and ray species have mainly occurred in incidental fisheries. Now they are increasingly being directly targeted due to the depleted status of traditionally targeted species. The life history characteristics of many elasmobranch species make them more sensitive to high rates of fishing mortality. The combination of these factors has resulted in the known local depletion of several elasmobranch species; including the barndoor skate, Raja laevis, of the Northwest Atlantic and the common skate, Raja batis, of Irish Sea. The longnose skate, Raja rhina, occurs commonly as incidental catch in trawl fisheries off the coast of California, Oregon and Washington. Commercial landings of skates, including R. rhina, have increased dramatically along the U.S. West coast. The objectives of this study have been to calculate accurate growth and maturity parameters for Raja rhina in order that the vulnerability of this species to fishing mortality can be assessed. The slow growth rates (k=0.04 to 0.06) and late ages-at-50% maturity (11 to 16 years with maximum ages between 15 and 22 years, depending on sex and region) which were calculated indicate that this species may be at great risk of depletion in the future. Survey biomass trends indicate that R. rhina populations have remained stable over the past twenty years. However, the possibility that biomass levels in the distant past were much higher than they are at present cannot be ruled out. It is recommended that the collection of fishery-dependent data for this species and other skate species begins immediately. This information, along with the results found in this are needed for a proper assessment for Raja rhina, so that the effects of current fishing pressures can be evaluated and regulated appropriately. / Graduation date: 2006

Forest harvest can have significant impacts on forest ecosystems that may influence the capacity of soils to sequester carbon (C). The microbial community controls decomposition, which is a critical process in partitioning litter- and root-C between CO₂ and storage in semi-permanent soil-C pools. The objectives of this study were to determine the effect of clear-cutting and stand age on: 1) temporal dynamics of soil microbial community (SMC) structure and physiological status; and 2) shifts among microbial functional groups in taking up ¹³C-labeled plant materials during decomposition. The experiment was conducted in Douglas-fir ecosystems within the Gifford Pinchot National Forest, Washington. We chose stands of three different ages: old-growth where trees are between 300 and 500 years old; an 8-year old stand; and a 25-year old stand. Phospholipid fatty acid (PLFA) profiling and ¹³C-PLFA labeling techniques along with the ratio of saturated to monounsaturated PLFAs and the ratios of cyclopropyl PLFAs to their monoenoic precursors as microbial physiological stress markers were utilized. Microbial PLFA profiles showed that SMC structure and physiological status was most affected by season and secondarily by time since clear-cutting. Total microbial biomass and bacterial and fungal biomass were significantly reduced in CC8 but not in CC25 sites relative to old-growth sites. Total microbial biomass concentration was lowest and the stress indicators were highest in August, which corresponded to low soil moisture and high temperatures. The relative amount of ¹³C incorporated into PLFAs was also influenced by stand age and ¹³C source (¹³C-labeled litter vs. ¹³C-labeled root material). A significantly greater amount of ¹³C was incorporated in CC8 samples compared to OG1 samples in five out of the seven sample dates. Additionally, a significantly greater proportion of ¹³C was incorporated into soil samples containing the ¹³C-labeled litter material relative to samples containing ¹³C-labeled root material in four out of the seven dates. In general, 18:lω9 and 18:2ω6,9 (common fungal biomarkers) had the greatest amount of ¹³C incorporation throughout the study period in both clear-cut and old-growth sites, indicating the important role of fungi in the decomposition of litter and root material and translocation of C within soil layers. / Graduation date: 2006

Juvenile coho salmon (101-400 mm) were sampled by purse seine off the Pacific Coast from Waatch Point, Washington to Four Mile Creek, Oregon, out to 30 mi offshore, during the months of May, June, and September in 1982 and 1983. Sea surface temperature, surface salinity, surface chlorophyll-a concentration, and Secchi depth were measured at each station. Sea surface temperatures were higher in 1983 than in 1982, while surface chlorophyll-a concentrations and surface salinities were lower. Catch data were not highly correlated with any of the four physical parameters measured. Strong northerly winds and strong upwelling tended to disperse juvenile coho offshore and south. Fish were found closer inshore during periods of weak winds and weak upwelling. In both years the center of distribution of the fish appeared to shift northward as the summer progressed. Larger fish, in general, were found farther north and offshore throughout the year. / Graduation date: 1985

The Van Dyke's salamander (Plethodon vandyke,) is a rare species endemic to Washington State. It has been found in cool moist microhabitats along streams, splash zones of waterfalls, and headwater seeps. We explored the association of the Van Dyke's salamander with hydrologic condition, geomorphology, disturbance characteristics, and vegetation structure in first- and second-order streams, and headwater seeps in the Cascade Range of Washington. We conducted salamander surveys and measured habitat characteristics at 50 streams and 40 seeps May-October 2000-2002. We described Van Dyke's salamander occurrence in stream and seep sites at three spatial scales: between sites, within sites, and between microhabitat sites. Using presence and absence as the response, we fit logistic regression models predicting Van Dyke's salamander occurrence. To identify the model that best fit the data, we ranked a priori models using Bayesian Information Criterion (BIC). Results were consistent for both stream and seep sites, at all three spatial scales. Best approximating models indicated that Van Dyke's salamander occurrence at sites was related to geological and hydrological habitat characteristics that provided hydnc and thermal stability. The probability of Van Dyke's salamander occurrence along streams was associated with habitat characteristics that protected salamanders from exposure, provided a source cover, and stream habitat types providing splash zone areas. Between streams, Van Dyke's salamander occurrence was positively associated with the proportion of valley walls with canopy cover <5%, the proportion of the stream channel dominated by bedrock, boulder, or soil substrates, and additional stream channels entering the main channel. Within streams, the probability of Van Dyke's salamander occurrence increased with the presence of non-forested areas, the presence of bedrock dominated stream habitat types, and the presence of vertical or V-shaped valley wall morphology. Between microhabitat sites, the probability of Van Dyke's salamander occurrence increased with an absence of trees, the presence of seeps, and the presence of small cobble sized substrates. The probability of Van Dyke's salamander occurrence in seeps was associated with habitat characteristics that protected salamanders within the larger landscape, provided a moisture gradient from dry to saturated, and the presence of cover objects. Between seeps, Van Dyke's salamander occurrence was positively associated with seep faces having a dry and sheeting hydrology, and with seep faces >5 m high. Within seeps, the probability of Van Dyke's salamander occurrence was negatively associated with seeps that had proportionately more point measures of total overhead cover that were >25%. Between microhabitat sites, the probability of Van Dyke's salamander occurrence was positively associated with an increase in the percent cover of small cobble, small gravel, and bedrock substrates. We conducted mark-recapture surveys of the Van Dyke's salamander at two high-gradient stream sites located within the Cascade Range of Washington State, June-November 2002. Sites known to support populations of the Van Dyke's salamander were chosen, and were ecologically different. One site, lacking significant overstory and located within the blast zone created by the 1980 eruption of Mount St. Helens, was surveyed 10 times. The other site, located in an old-growth coniferous stand, was surveyed 11 times. Abundance of salamanders at the blast zone site was estimated to be 458 (95% Cl: 306-739). Abundance of salamanders at the old-growth site was estimated to be 100 individuals (95% Cl: 61-209). Capture probabilities were extremely low (5 = <0.10) for all trapping occasions at both sites, with an average capture probability for the two sites of 0.038 (range = 0.02-0.09). Analysis of movement patterns suggested that most individual salamanders had home ranges <2 m, at least when moving on or near the surface. Individuals were recaptured under the same cover object as initial capture 36% of the time, and 89% of the recaptured individuals moved <2 m. Our results indicated that populations of the Van Dyke's salamander were rare on the landscape, even within the species documented range. Van Dyke's salamander occurrence was associated with geological and hydrological habitat characteristics that created microhabitats favorable for a species that is especially sensitive to heat and drying due to physiological constraints. Animals were difficult to detect due to fossorial habits and low capture probabilities, and it is likely that the Van Dyke's salamander was not detected even at sites where it existed. Life history characteristics, such as lunglessness and fossorial habits, low capture probabilities, and low abundances make it difficult to manage for and protect the Van Dyke's salamander. However, habitat associations may be used to identify and protect habitats suitable for Van Dyke's salamander occurrence. / Graduation date: 2004

In the Pacific Northwest (PNW), concern about the impacts of climate and land cover change on water resources, flood-generating processes, and ecosystem dynamics emphasize the need for a mechanistic understanding of the interactions between forest canopies and hydrological processes. A detailed measurement and modeling program during the 1999 and 2000 hydrologic years characterized hydrological conditions and processes in a 500-600 year old Douglas fir-western hemlock seasonal temperate rainforest. The measurement program included sub-canopy arrays of radiometers, tipping bucket rain gauges, and soil temperature and moisture probes, to supplement a vertical temperature and humidity profile within the forest canopy. Analysis of the precipitation interception characteristics of the canopy indicated that the mean direct throughfall proportion was 0.36, and the mean saturation storage was 3.3 mm. Evaporation from small storms insufficient to saturate the canopy comprised 19% of the net interception loss, and canopy drying and evaporation during rainfall accounted for 47% and 33% of the net loss, respectively. Results of the measurement program were used to modify the Simultaneous Heat and Water (SHAW) model for forested systems. Changes to the model include improved representation of interception dynamics, stomatal conductance, and within-canopy energy transfer processes. The model effectively simulated canopy air and vapor density profiles, snowcover processes, throughfall, soil water content profiles, shallow soil temperatures, and transpiration fluxes for both a calibration period and for an uncalibrated year. Soil warming at bare locations was delayed until most of the snowcover ablated due to the large heat sink associated with the residual snow patches. During the summer, simulated evapotranspiration decreased from a maximum monthly mean of 2.17 mm day����� in July to 1.34 mm day����� in September, as a result of declining soil moisture and net radiation. Our results indicate that a relatively simple parameterization of the SHAW model for the vegetation canopy can accurately simulate seasonal hydrologic fluxes in this environment. Application and validation of the model in other forest systems will establish similarities and differences in the interactions of vegetation and hydrology, and assess the sensitivity of other systems to natural and anthropogenic perturbations. / Graduation date: 2002

Ambystoma macrodactylum (long-toed salamander) and A. gracile (northwestern salamander) are two common salamander species occupying key trophic positions in mountain ponds of Mount Rainier National Park. The objective of this research was to document and evaluate the distributions and abundances of the two species, relative to habitat characteristics of ponds in the park. Amphibian distributions and abundances were assessed in 20 ponds from June through September 1993 to 1996. Nutrient concentrations (total nitrogen, Kjeldahl-N, total phosphorus, and orthophosphate-P), habitat characteristics (surface area, depth, elevation, substratum organic content lost on ignition, amount of coarse woody debris, aquatic vegetation, and bottom firmness), and water quality (temperature, dissolved oxygen, alkalinity, conductivity, and pH) were measured. Distinct habitat associations were found for each Ambystoma species. Ponds with one species only were different in surface area, maximum depth, substratum organic content, and elevation. Ponds with A. macrodactylum were small, shallow, high in elevation, and had firm sediments low in organic matter relative to A. gracile ponds. Ambystoma macrodactylum ponds typically contained little coarse woody debris relative to the amount of aquatic vegetation. Ambystoma gracile ponds were large, deep, low in elevation, had flocculent sediment high in organic content, abundant coarse woody debris, and little aquatic vegetation relative to A. macrodactylum ponds. Two ponds supported reproducing populations of both species and exhibited habitat characteristics intermediate to the allopatric pond types. These findings suggest that habitat complexity plays an important role in the segregation of A. macrodactylum and A. gracile. / Graduation date: 2000

The relationship of coastal cutthroat trout (Oncorhynchus clarki clarki) populations in the Muck Creek basin, a 238 km�� southern Puget Sound stream basin in western Washington, was examined using starch gel electrophoresis and meristic analysis. Coastal cutthroat trout were collected from six sites throughout the basin including tributaries, portions of the mainstem, and a lake. Four sites contained only resident trout, the lower mainstem contained resident and anadromous trout, and the lake contained only mature anadromous trout based on size and appearance. Patterns of allelic and meristic variation suggest a significant structuring and separation of coastal cutthroat trout populations in the basin. The lake population was distinguished from the other populations by significant differences in allele frequencies and meristic characters. The other sites grouped more closely together with significant variation among and between sites meristically and at several loci. / Graduation date: 1996

Approximately 5,500 years ago a discreet period of wetter and cooler environmental conditions prevailed across the southern Columbia Plateau. This period was marked by the first prominent episodes of erosion to occur along the lower Snake River following the height of the Altithermal and eruption of Mt. Mazama during the mid post-glacial. In addition to the reactivation of small stream courses choked with debris and sediment, large stream channels began downcutting and scouring older terrace faces incorporated with large accumulations of Mazama ash. The resulting degradation of aquatic habitats forced concurrent changes within human economies adapted to the local riverine-environments. These adjustments reported for the Tucannon phase time period along the lower Snake River are notable and demonstrate the degree to which Cascade phase culture was unsuccessful in coping with environmental instability at the end of the Altithermal time period. This successionary event has demonstratively become the most significant post-glacial, qualitative change to occur in the lifeways of lower Snake River people prior to Euro-American influence. / Graduation date: 1995

Spatially explicit ecosystem service valuation (ESV) allows for the identification of the location and magnitude of services provided by natural ecosystems to human activities along with a measure of their significance based upon economic valuation. While ESV has been used to provide new insight into land use management, few studies have identified the connections between the values of ecosystem services and ecological sensitivity to nitrogen loading despite a growing body of ecosystem service literature. This research combines a GIS-based, value transfer approach to map ecosystem services in the Lower Yakima River Basin (LYRB), Washington, USA, along with estimates of nitrogen loading to identify how nitrogen management may affect ecosystem services in the basin. This analysis combines values of ecosystem services with estimates of nitrogen loading and identifies subwatersheds and specific parcels within a Groundwater Management Area (GWMA) most susceptible to reductions in ecosystem services due to excess nitrogen loading. Based on the benefit transfer analysis, wetlands and forested areas have disproportionately high values of ecosystem services when compared to their land area in the LYRB, while pasture and cultivated crops contribute much less to the total value of ecosystem service flows in proportion to the total area in the LYRB. Across the study area estimated nitrogen loads are strongly driven by the location of concentrated animal feeding operations (CAFOs) and cultivated crops. Areas of particularly high nitrogen loading and high ESV may highlight specific areas for achieving immediate success in increasing or maintaining ecosystem services through appropriately focused regulatory mechanisms. The land cover analysis however, completely neglects the values and importance of subsurface processes and groundwater resources in ecosystem service assessment, and therefore an econometric model is applied to estimate willingness to pay (WTP) to maintain safe nitrate levels in private wells. Through the incorporation of WTP estimates for groundwater quality, a more complete economic and ecological perspective on the effects of landscape N loading in the study site is highlighted. The results of these estimates clearly indicate that ecosystem services from groundwater should be considered to have significant value in the LYRB. Further economic valuation data on specific land cover types and the value of groundwater quality, whether from primary studies or meta-analysis, is needed to refine relative measures of ecosystem service values and more confidently describe these values in specific dollar amounts. Additionally, limits in spatial data resolution may contribute to errors in location and magnitude of ecosystem services, and is an area in need of further development. Despite these potential limitations, this analysis highlights a promising direction for combining spatially explicit ecosystem service valuation with nutrient loading data to identify the location and potential magnitude of effects on ecosystem services from management practices. / Graduation date: 2013