Journal Articles

Local Variability Mediates Vulnerability of Trout Populations to Land Use and Climate Change
Brooke E. Penaluna, Jason B. Dunham, Steve F. Railsback, Ivan Arismendi, Sherri L. Johnson, Robert E. Bilby, Mohammad Safeeq, Arne E. Skaugset

Land use and climate change occur simultaneously around the globe. Fully understanding their separate and combined effects requires a mechanistic understanding at the local scale where their effects are ultimately realized. Here we applied an individual-based model of fish population dynamics to evaluate the role of local stream variability in modifying responses of Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) to scenarios simulating identical changes in temperature and stream flows linked to forest harvest, climate change, and their combined effects over six decades. We parameterized the model for four neighboring streams located in a forested headwater catchment in northwestern Oregon, USA with multi-year, daily measurements of stream temperature, flow, and turbidity (2007– 2011), and field measurements of both instream habitat structure and three years of annual trout population estimates. Model simulations revealed that variability in habitat conditions
among streams (depth, available habitat) mediated the effects of forest harvest and climate change. Net effects for most simulated trout responses were different from or less than the sum of their separate scenarios. In some cases, forest harvest countered the effects of climate change through increased summer flow. Climate change most strongly influenced trout (earlier fry emergence, reductions in biomass of older trout, increased biomass of young-of-year), but these changes did not consistently translate into reductions in biomass over time. Forest harvest, in contrast, produced fewer and less consistent responses in trout. Earlier fry emergence driven by climate change was the most consistent simulated response, whereas survival, growth, and biomass were inconsistent. Overall our findings indicate a host of local processes can strongly influence how populations respond to broad scale effects of land use and climate change.

DISCIPLINE: Fisheries    STUDY: Trask    TYPE: Journal Articles    TAGS: trout, land use, climate change
Instream cover and shade mediate avian predation on trout in semi-natural streams
Brooke E. Penaluna, Jason B. Dunham, David L.G. Noakes

Piscivory by birds can be significant, particularly on fish in small streams and during seasonal low flow when available cover from predators can be limited. Yet, how varying amounts of cover may change the extent of predation mortality from avian predators on fish is not clear. We evaluated size-selective survival of coastal cutthroat trout (Oncorhynchus clarkii clarkii) in replicated semi-natural stream sections. These sections provided high (0.01 m2 of cover per m2 of stream) or low (0.002 m2 of cover per m2 of stream) levels of instream cover available to trout and were closed to emigration. Each fish was individually tagged, allowing us to track retention of individuals during the course of the 36-day experiment, which we attributed to survival from predators, because fish had no other way to leave the streams. Although other avian predators may have been active in our system and not detected, the only predator observed was the belted kingfisher Megaceryle alcyon, which is known to prey heavily on fish. In both treatments, trout >20.4 cm were not preyed upon indicating an increased ability to prey upon on smaller individuals. Increased availability of cover improved survival of trout by 12% in high relative to low cover
stream sections. Trout also survived better in stream sections with greater shade, a factor we could not control in our system. Collectively, these findings indicate that instream cover and shade from avian predators can play an important role in driving survival of fish in small streams or during periods of low flow.

DISCIPLINE: Fisheries    STUDY:    TYPE: Journal Articles    TAGS: trout survival, refuge, piscivory, body size, low flow, experiment
Potential Risks to Freshwater Aquatic Organisms Following a Silvicultural Application of Herbicides in Oregon's Coast Range
Jeff Louch, Vickie Tatum, Ginny Allen, V. Cody Hale, Jeffrey McDonnell, Robert J. Danehy, George Ice

Glyphosate, aminomethylphosphonic acid (AMPA), imazapyr, sulfometuron methyl (SMM), and metsulfuron methyl (MSM) were measured in streamwater collected during and after a routine application of herbicides to a forestry site in Oregon’s Coast Range. Samples were collected at three stations: HIGH at the fish/no-fish interface in the middle of the harvest/spray unit; MID at the bottom of the unit; and LOW downstream of the unit. All herbicides were applied by helicopter in a single tank mix. AMPA, imazapyr, SMM, and MSM were not detected (ND) in any sample at 15, 600, 500, and 1000 ng/L, respectively. A pulse of glyphosate peaking at ≈62 ng/L manifested at HIGH during the application. Glyphosate pulses peaking at 115 ng/L (MID) and 42 ng/L (HIGH) were found during the first two post-application storm events 8 and 10 days after treatment (DAT), respectively: glyphosate was <20 ng/L (ND) at all stations during all subsequent storm events. All glyphosate pulses were short-lived (4 to 12 h). Glyphosate in baseflow was ≈25 ng/L at all stations 3 DAT and was still ≈25 ng/L at HIGH, but ND at the other stations, 8 DAT: subsequently, glyphosate was ND in baseflow at all stations. These results show that aquatic organisms were subjected to multiple short-duration, low-concentration glyphosate pulses corresponding to a cumulative time-weighted average (TWA) exposure of 6634 ng/L*h. Comparisons to TWA exposures associated with a range of toxicological endpoints for sensitive aquatic organisms suggests a margin of safety exceeding 100 at the experimental site, with the only potential exception resulting from the ability of fish to detect glyphosate via olfaction. For imazapyr, SMM, and MSM the NDs were at concentrations low enough to rule out effects on all organisms other than aquatic plants, and the low concentration and (assumed) pulsed nature of any exposure should mitigate this potential.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Journal Articles    TAGS: forestry, Glyphosate, herbicides, pulsed exposure, time-weighted average exposure
Effect of bedrock permeability on stream base flow mean transit time scaling relationships: 2. Process study of storage and release
V. Cody Hale, Jeffrey J. McDonnell, Michael K. Stewart, D. Kip Solomon, Jim Doolitte, George G. Ice, Robert T. Pack

In Part 1 of this two-part series, Hale and McDonnell (2016) showed that bedrock permeability controlled base flow mean transit times (MTTs) and MTT scaling relations across two different catchment geologies in western Oregon. This paper presents a process-based investigation of storage and release in the more permeable catchments to explain the longer MTTs and (catchment) area-dependent scaling. Our field-based study includes hydrometric, MTT, and groundwater dating to better understand the role of subsurface catchment storage in setting base flow MTTs. We show that base flow MTTs were controlled by a mixture of water from discrete storage zones: (1) soil, (2) shallow hillslope bedrock, (3) deep hillslope bedrock, (4) surficial alluvial plain, and (5) suballuvial bedrock. We hypothesize that the relative contributions from each component change with catchment area. Our results indicate that the positive MTT-area scaling relationship observed in Part 1 is a result of older, longer flow path water from the suballuvial zone becoming a larger proportion of streamflow in a downstream direction (i.e., with increasing catchment area). Our work suggests that the subsurface permeability structure represents the most basic control on how subsurface water is stored and therefore is perhaps the best direct predictor of base flow MTT (i.e., better than previously derived morphometric-based predictors). Our discrete storage zone concept is a process explanation
for the observed scaling behavior of Hale and McDonnell (2016), thereby linking patterns and processes at scales from 0.1 to 100 km2.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Journal Articles    TAGS: bedrock permeability, MTT, storage and release
Effect of bedrock permeability on stream base flow mean transit time scaling relations: 1. A multiscale catchment intercomparison
V. Cody Hale, Jeffery J McDonnell

The effect of bedrock permeability and underlying catchment boundaries on stream base flow mean transit time (MTT) and MTT scaling relationships in headwater catchments is poorly understood. Here we examine the effect of bedrock permeability on MTT and MTT scaling relations by comparing 15 nested research catchments in western Oregon; half within the HJ Andrews Experimental Forest and half at the site of the Alsea Watershed Study. The two sites share remarkably similar vegetation, topography, and climate and differ only in bedrock permeability (one poorly permeable volcanic rock and the other more permeable sandstone). We found longer MTTs in the catchments with more permeable fractured and weathered sandstone
bedrock than in the catchments with tight, volcanic bedrock (on average, 6.2 versus 1.8 years, respectively). At the permeable bedrock site, 67% of the variance in MTT across catchments scales was explained by drainage area, with no significant correlation to topographic characteristics. The poorly permeable site had opposite scaling relations, where MTT showed no correlation to drainage area but the ratio of median flow path length to median flow path gradient explained 91% of the variance in MTT across seven catchment scales. Despite these differences, hydrometric analyses, including flow duration and recession analysis, and storm response analysis, show that the two sites share relatively indistinguishable hydrodynamic behavior. These results show that similar catchment forms and hydrologic regimes hide different subsurface routing, storage, and scaling behavior—a major issue if only hydrometric data are used to define hydrological similarity for assessing land use or climate change response.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Journal Articles    TAGS: bedrock permeability, MTT
In Lieu of the Paired Catchment Approach: Hydrologic Model Change Detection at the Catchment Scale
Zégre, N., A.E. Skaugset, N.A. Som, J.J. McDonnell, L.M. Ganio

The paired catchment approach has been the predominant method for detecting the effects of disturbance on catchment-scale hydrology. Notwithstanding, the utility of this approach is limited by regression model sample size, variability between paired catchments, type II error, and the inability of locating a long-term suitable control. An increasingly common practice is to use rainfall-runoff models to discern the effect of disturbance on hydrology, but few hydrologic model studies (1) consider problems associated with model identification, (2) use formal statistical methods to evaluate the significance of hydrologic change relative to variations in rainfall and streamflow, and (3) apply change detection models to undisturbed catchments to test the approach. We present an alternative method to the paired catchment approach and improve on stand-alone hydrologic modeling to discern the effects of forest harvesting at the catchment scale. Our method combines rainfall-runoff modeling to account for natural fluctuations in daily streamflow, uncertainty analyses using the generalized likelihood uncertainty estimation method to identify and separate hydrologic model uncertainty from unexplained variation, and GLS regression change detection models to provide a formal experimental framework for detecting changes in daily streamflow relative to variations in daily hydrologic and climatic data.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: change detection, hydrologic modeling, forest harvest, time series, uncertainty analysis, land use, Forest Hydrology, Paired Watershed
Factors Influencing Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) Seasonal Survival Rates: a Spatially Continuous Approach within Stream Network
Berger, A.M., R.E. Gresswell

Mark–recapture methods were used to examine watershed-scale survival of coastal cutthroat trout (Oncorhynchus clarkii clarkii) from two headwater stream networks. A total of 1725 individuals (‡100 mm, fork length) were individually marked and monitored seasonally over a 3-year period. Differences in survival were compared among spatial (stream segment, subwatershed, and watershed) and temporal (season and year) analytical scales, and the effects of abiotic (discharge, temperature, and cover) and biotic (length, growth, condition, density, movement, and relative fish abundance) factors were evaluated. Seasonal survival was consistently lowest and least variable (years combined) during autumn (16 September – 15 December), and evidence suggested that survival was negatively associated with periods of low stream discharge. In addition, relatively low (–) and high (+) water temperatures, fish length (–), and boulder cover (+) were weakly associated with survival. Seasonal abiotic conditions affected the adult cutthroat trout population in these watersheds, and low-discharge periods (e.g., autumn) were annual survival bottlenecks. Results emphasize the importance of watershed-scale processes to the understanding of population-level survival.

DISCIPLINE: Fisheries    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: Mark–recapture, abiotic factors, biotic factors, water temperatures, boulder cover
Passive Integrated Transponder Tag Retention Rates in Headwater Populations of Coastal Cutthroat Trout
Bateman, D.S., R.E. Gresswell, A.M. Berger

Passive integrated transponder (PIT) tags have desirable qualities (e.g., unique identification, indefinite tag life, and capacity for remote detection) that make them useful for evaluating survival, growth, and movement of fish, but low tag retention rates can confound data interpretation. Although the effects of PIT tags on short-term growth and survival have been minimal and tag retention rates in laboratory and field studies using only juvenile individuals have been high, tag retention rates for fish at different ontological stages (including reproductively active males and females) remain unknown. We evaluated tag retention rates in wild populations of coastal cutthroat trout Oncorhynchus clarkii clarkii in three catchments of western Oregon using a double-marking approach (i.e., the adipose fin was removed from all fish that were PIT-tagged). Tags were inserted into the body cavities of fish 100 mm or more in length (fork length; range¼100–250 mm). In the study catchments, this size range includes both juvenile and mature fish. Tag retention rates were approximately 25% lower than those reported by previous studies of juvenile salmonids alone. A number of PIT tags were recovered in redds, indicating that mature individuals eject tags during spawning. Although some coastal cutthroat trout retained PIT tags for up to 4 years, others expelled them repeatedly and were implanted with a minimum of three different PIT tags during the same period.

DISCIPLINE: Fisheries    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: Passive integrated transponder (PIT) tags, retention rates, double-mark, juvenile salmonids
Corrected Prediction Intervals for Change Detection in Paired Watershed Studies
Som, N.A., N.P. Zegre, L.M. Ganio, A.E. Skaugset

Autoregressive process pHydrological data may be temporally autocorrelated requiring autoregressive process parameters to be estimated. Current statistical methods for hydrological change detection in paired watershed studies rely on prediction intervals, but the current form of prediction intervals does not include all appropriate sources of variation. Corrected prediction intervals for the analysis of paired watershed study data that include variation associated with covariance and linear model parameter estimation are presented. We provide an example of their application to data from the Hinkle Creek Paired Watershed Study located in the western Cascade foothills of Southern Oregon, USA. Research implications of using the correct prediction limits and incorporating the estimation uncertainty of aarameters are discussed.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: paired watershed study, generalized least squares, Prasad-Rao mean-squared error estimator, stream discharge, time series
The Effect of Timber Harvest on Summer Low Flows, Hinkle Creek, Oregon
Surfleet, C.G., A.E. Skaugset

Changes to summer low flows from forest harvesting were measured for a gauged fourth-order stream in the Hinkle Creek Paired Watershed Study. At the gauged stream, August streamflow increased an average of 1.9 mm/year (45%) for the three summers following forest harvest of 13% of a 1,084 ha watershed. Following a second harvest of an additional 13% of the watershed the August streamflow increased by 4.5 mm (106%) the first summer and 2.0 mm (47%) the second summer. Master recession curves were fit to the gauged watersheds and the resulting recession coefficients were used to predict low flows from small watersheds nested within the gauged watersheds. The estimated low flows were used to evaluate changes in summer low flows associated with forest harvest for the small watersheds. Using recession curve analysis, the estimated range of the increase for average August streamflow for the four small watersheds in the Hinkle Creek Paired Watershed Study was 1.7 mm to 4.4 mm the first summer following forest harvest. August streamflow in the small watersheds was not distinguishable from preharvest levels within 5 years for all but one watershed, which had the highest proportion of watershed area harvested.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: low flow, recession curve, Forest management, water yield, Forest Hydrology


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