King County Department of Natural Resources and Parks

Benthic macroinvertebrate taxa vary in their sensitivities to water quality and habitat conditions, contributing to their extensive use as ecological indicators. As climate change and landscape alteration increasingly impact stream temperatures, interest is growing in expanding our knowledge of how macroinvertebrates are affected by current and future thermal conditions. Using samples from 3501 sites, we evaluated relationships between macroinvertebrate taxa and modeled stream temperatures across Oregon and Washington, in the U.S. Pacific Northwest. We used Maximum Weekly Maximum Temperature (MWMT) values from the NorWeST temperature dataset, which is the same metric used for numeric water temperature standards in Oregon and Washington. MWMT captures peak thermal stress, when cold-water adapted aquatic biota are closest to their upper physiological limits. For each macroinvertebrate taxon, we characterized relationships between MWMT and their distributions with three measures: 1) central thermal tendency, based on weighted average (WA) optima calculations and relative abundance data; 2) lower and upper thermal limits, based on the 10th and 90th percentiles of taxon occurrence, using presence data; and 3) thermal sensitivity curve shape, based on Generalized Additive Model (GAM) plots. We assigned 521 taxa, from species to phyla, to seven thermal preference categories, ranging from cold and warm stenotherms (narrow range) to eurythermal (wide range). Thermal sensitivity and variability within each taxonomic group were identified for establishing taxonomic targets for regional monitoring programs. We also developed the Macroinvertebrate Thermal Tolerance Index (MTTI) to represent the assemblage-level response to available thermal habitats, using WA optima and relative abundances for 324 taxa. The MTTI model had a strong relationship with modeled temperatures (R2 = 0.68) and a root-mean-square-error of 2.5 °C. Our work builds on previous regional and national efforts to identify thermal indicator taxa by using modeled stream network temperatures and a thermal metric that corresponds directly to regional water temperature standards. Both the taxa thermal preferences and the MTTI can be used to help identify causes of biological impairment, prioritize restoration and protection actions, and monitor assemblage-wide changes in thermal tolerance over time.

Abstract Declines in populations of Pacific salmon Oncorhynchus spp. in the Pacific Northwest have led to listings under the Endangered Species Act. One objective of current recovery efforts is the restoration of freshwater and estuarine habitats, which had been occurring prior to Endangered Species Act listing but increased dramatically afterwards. However, few listed populations are improving. We believe that there are five factors contributing to the lack of population response to habitat restoration: Not enough restoration has been done.We are not doing the right things in the right places at the right times.Ongoing habitat degradation is offsetting restoration benefits.Not enough time has passed.Monitoring has been inadequate to detect changes in Pacific salmon abundance. All factors contribute to the disappointing progress on Pacific salmon recovery, although their importance varies. Two factors are more consistently significant than the others. Resources available to address habitat damage remain insufficient. The scale of the problem is large, so the response needs to be correspondingly large to yield desired outcomes. Of equal significance is the failure of restoration programs to identify elements controlling fish production. Implementing the right projects in the right places is key to improving the outcomes of restoration.

Abstract Preventing invasive species establishment is a global conservation priority, yet limited management resources oftentimes restrict sites to target for prevention or monitoring. Risk assessments based on habitat suitability can identify sites most vulnerable to invasion that should be prioritized for preventative actions. Since habitat suitability is the result of interactions between environmental and organismal attributes, analyses should incorporate individual variability in demographics expected in an invasive population. Individual‐based models (IBMs) can predict habitat suitability by accounting for interactions between environmental conditions and individual‐level variability. We developed an IBM to predict suitability of rivers in the northern United States to the invasive fishes silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) and explored the projected effects of climate change on habitat suitability. All rivers supported adult survival, although complete survival of all adult demographics and positive growth only occurred in approximately 45% (17 of 38) of rivers for silver carp and 26% (10 of 38) of rivers for bighead carp. Only the largest individuals at the time of introduction survived in rivers where adult mortality occurred. Most rivers were unsuitable for young‐of‐year (89% and 92% of rivers for silver carp and bighead carp respectively). Climate change simulations had relatively little effect on adult habitat suitability but resulted in up to four times the number of rivers being suitable for young‐of‐year by the late‐21st century and greatly extended the viable spawning season by up to an additional 65 days for silver carp and 77 days for bighead carp. Synthesis and applications. Our approach of using individual‐based models as a risk assessment tool informs proactive conservation planning by identifying sites for invasive species early detection monitoring, promoting the development of contingency response plans and allowing for proactive prevention efforts. Model predictions also provide specific management guidance regarding the size and life stages to target for monitoring efforts, which capture gears to use, and the most effective time to sample for early detection monitoring.

Restoring the health of urban streams has many of the characteristics of a wicked problem. Addressing a wicked problem requires managers, academics, practitioners, and community members to make negotiated tradeoffs and compromises to satisfy the values and perspectives of diverse stakeholders involved in setting restoration project goals and objectives. We conducted a gap analysis on 11 urban stream restoration projects to identify disconnections, underperformance issues, and missing processes in the project structures used to develop restoration project goals and objectives. We examined the gap analysis results to investigate whether managers appropriately identified problem statements and met stated objectives. Projects that aimed to restore overall stream health commonly fell short for various reasons, including limited stakeholder and community input and buy-in, revealing potential limitations in the breadth of objectives, values, and stakeholder perspectives and knowledge types. Projects that emphasized integrating community values and diverse knowledge types tended to meet the expected outcomes of restoring stream processes through incremental solutions. Managers implementing more holistic solutions and values-driven approaches are more likely to consider diverse viewpoints from a variety of community local institutions. Based on these and other results, we propose a conceptual framework that integrates diverse perspectives and knowledge to enhance social and ecological outcomes of urban stream restoration. The framework also emphasizes the importance of setting objectives that support incremental solutions to foster more realistic expectations amongst stakeholders.

Tabor RA, Perkin EK, Beauchamp DA, Britt LL, Haehn R, Green J, Robinson T, Stolnack S, Lantz DW, Moore ZJ. 2021. Artificial lights with different spectra do not alter detrimental attraction of young Chinook salmon and sockeye salmon along lake shorelines. Lake Reserv Manage. XX:XXX–XXX. Artificial light at night (ALAN) is common in lakes with developed shorelines, especially prevalent in the nearshore areas where juvenile fishes, including salmonids, are present. One concern is that fishes may be attracted to ALAN and become more vulnerable to predators. The use of longer wavelength lights has been suggested to reduce the effects of ALAN; however, the response in juvenile salmonids is not well known. We tested the hypothesis that longer wavelength lights would attract fewer subyearling Chinook salmon (Oncorhynchus tshawytscha) and sockeye salmon (O. nerka) than shorter wavelength lights. Test lights included 4 LED lights, an incandescent light, and a high-pressure sodium light (HPS). In total, 13 experimental trials were conducted in 2017 and 2018, and in total 1769 Chinook salmon and 870 sockeye salmon were collected with beach seines. The mean catch rate (number per beach seine set) of subyearling salmonids was 51.0 for lighted treatments but only 6.6 for control treatments (no light). In both years, we did not find any significant difference in catch rates for either species between either of the longer wavelength lights (red-filter and yellow-filter LED lights) and other lights, and thus we rejected the hypothesis that longer wavelength light would attract fewer subyearling salmonids. For these early life stages of salmon in shallow shoreline habitats, reducing the intensity of light present is likely more important than altering the spectral composition when trying to minimize maladaptive attraction to ALAN.

Abstract Estuarine habitats provide rearing opportunities for the juvenile life stage of anadromous fishes. Because survival is positively correlated with juvenile performance, these estuarine habitats play an important role in population abundance and productivity. To provide information for the recovery of several depressed stocks of Chinook salmon in the Columbia River Basin, we sought to identify the factors that explain variability in performance. Using otolith‐derived estimates of juvenile somatic growth rate as an index of recent performance, we observed a negative nonlinear relationship between growth rate and day of year, and a decreasing and increasing trend of growth rate over the 8 years of this study and distance from the river mouth respectively. Using a generalised linear modelling approach, we found that variability in juvenile somatic growth rate was best explained by where and when individuals were collected, their body size, contaminant loads, stock of origin, and whether a fish was hatchery produced or unmarked. Lastly, we argue that a considerable improvement to the growth rate of juveniles in estuarine habitats is physiologically possible. The results of this 8‐year study provide a baseline of the performance of juvenile Chinook salmon to evaluate habitat restoration programs and to compare against future anthropogenic conditions.