Climate vulnerability assessment for Pacific salmon and steelhead in the California Current Large Marine Ecosystem.

Major ecological realignments are already occurring in response to climate change. To be successful, conservation strategies now need to account for geographical patterns in traits sensitive to climate change, as well as climate threats to species-level diversity. As part of an effort to provide such information, we conducted a climate vulnerability assessment that included all anadromous Pacific salmon and steelhead (Oncorhynchus spp.) population units listed under the U.S. Endangered Species Act. Using an expert-based scoring system, we ranked 20 attributes for the 28 listed units and 5 additional units. Attributes captured biological sensitivity, or the strength of linkages between each listing unit and the present climate; climate exposure, or the magnitude of projected change in local environmental conditions; and adaptive capacity, or the ability to modify phenotypes to cope with new climatic conditions. Each listing unit was then assigned one of four vulnerability categories. Units ranked most vulnerable overall were Chinook (O. tshawytscha) in the California Central Valley, coho (O. kisutch) in California and southern Oregon, sockeye (O. nerka) in the Snake River Basin, and spring-run Chinook in the interior Columbia and Willamette River Basins. We identified units with similar vulnerability profiles using a hierarchical cluster analysis. Life history characteristics, especially freshwater and estuary residence times, interplayed with gradations in exposure from south to north and from coastal to interior regions to generate landscape-level patterns within each species. Nearly all listing units faced high exposures to projected increases in stream temperature, sea surface temperature, and ocean acidification, but other aspects of exposure peaked in particular regions. Anthropogenic factors, especially migration barriers, habitat degradation, and hatchery influence, have reduced the adaptive capacity of most steelhead and salmon populations. Enhancing adaptive capacity is essential to mitigate for the increasing threat of climate change. Collectively, these results provide a framework to support recovery planning that considers climate impacts on the majority of West Coast anadromous salmonids

Puget sound habitat status and trends monitoring program: nearshore and large river delta geospatial data and habitat status and trends monitoring metrics

The Puget Sound Habitat Status and Trends Monitoring (PSHSTM) program was developed to provide consistent salmon habitat status and trends data to support status reviews of Endangered Species Act (ESA) listed salmon populations across Puget Sound’s major population groups. Our approach primarily relies on readily available and regularly updated aerial imagery to consistently map key habitat features at a regional scale. We have developed a census-based approach to map key habitat features throughout the nearshore, large river delta, large river, and floodplain environments across Puget Sound. This presentation will focus on our mapping efforts in Puget Sound’s nearshore and large river delta environments, and the habitat status and trends metrics that will be derived from these efforts to support ESA listing reviews. In the nearshore environment, we are mapping overwater structures (e.g., docks, piers, bridges, buoys/floats, booms, aquaculture, and boat ramps), forested shoreline, and small embayment habitat features (e.g., lagoons, pocket estuaries, and blind tidal channels) for all ≈4,000 km of Puget Sound’s shoreline. In the large river delta environment, we are mapping tidal wetland areas, geomorphic delta boundaries, and channel features (e.g., distributaries and tidal channels) for all 17 large river deltas that drain into the Puget Sound, Hood Canal, and the Strait of Juan de Fuca. This census-based approach will provide a unique opportunity to develop consistent habitat status and trends metrics for habitat quantity and quality at a regional scale that can be used to inform ESA status reviews of listed salmon populations. We anticipate that the consistent regional-scale geospatial data sets developed from these efforts can be used to support a variety of other research and management needs

Quantifying the habitat and zoogeomorphic capabilities of spawning European barbel Barbus barbus, a lithophilous cyprinid

Suitable gravel availability is critical for the spawning success of lithophilous fishes, including redd builders. Redd construction during spawning can alter substrate characteristics, thereby influencing hydraulic conditions and sediment transport, highlighting the importance of spawning as a zoogeomorphic activity. Here, interactions between redd‐building fish and their spawning environment were investigated for European barbel Barbus barbus with a comparative approach across three English rivers: Teme (western), Great Ouse (eastern) and Idle (central). Sediment characteristics of spawning habitats were similar across the rivers, including subsurface fine sediment (<2 mm) content (≈20% dry weight), but elevated subsurface silt content and coarser surface sediments were found in the river Teme. Water velocities were similar at spawning sites despite differences in channel width and depth. Redds were characterized by a pit and tailspill, with no differences in surface grain‐size characteristics between these and the surrounding riverbed, but with topographic alteration (dimensions and tailspill amplitude) in line with those of salmonids. Estimates of the fraction of the bed that spawning barbel were capable of moving exceeded 97% in all rivers. Estimated reproductive potential varied significantly between the rivers Idle and Teme (3,098 to 9,715 eggs/m2), which was largely due to differences in barbel lengths affecting fecundity. Larger barbel, capable of producing and depositing more eggs, but in more spatially extensive redds, meaning fewer redds per given surface area of riverbed. Predictions of barbel egg mortality based on sand content were low across both rivers. The effects of silt on barbel egg and larvae development are unknown, but the levels detected here would significantly impact salmon egg mortality. Similarities in fish length to redd area and the size of moveable grains by spawning barbel and salmon suggest they have similar geomorphic effects on sediments, although fine sediment tolerance is highly divergent

River research and applications across borders

Rivers flow across national borders, unfettered by political distinctions, and the ecological health of rivers is closely linked to their degree of connectivity. River research today is more global than it has ever been, but we show that river research, engineering, and management still operate within homegrown local paradigms. As a basis for this discussion, we studied the citation networks surrounding the most widely cited papers in our field, assessing the degree to which researchers have collaborated across geographical boundaries and fully drawn from the international literature. Despite gains over time, our field remains surprisingly and pervasively provincial. The likely explanation for provincial bias is that researchers are generally more familiar and comfortable with their own research methods, sites, and agendas. However, local focus has tangible consequences. For example, contrasting paradigms and differing approaches to river restoration and to flood-risk management show that opportunities are lost when we fail to learn from the successes and failures of other regions. As Sharp and Leshner (2014; p. 579) have argued, "the search for solutions needs to draw upon the talents and innovative ideas of scientists, engineers, and societal leaders worldwide to overcome traditional and nationalistic paradigms that have so far been inadequate to meeting these challenges.

Relationships between channel characteristics, woody debris, and fish habitat in northwestern Washington streams

Relationships between large woody debris (LWD) and pool area or pool spacing varied with channel slope and channel width for streams in second-growth forests in northwest Washington. Pool spacing (expressed as the number of channel widths between pools) decreased as number of woody debris increased in both moderate-slope (0.02 \u3c slope \u3c 0.05) and low-slope (0.001 \u3c slope less than or equal to 0.02) channels, but the relationship was stronger in moderate-slope channels. Percent pool was also more strongly correlated with woody debris volume in moderate-slope channels than in low-slope channels. Multiple-regression analyses showed that pool spacing and percent pool were correlated with an interaction term between LWD abundance and channel slope, suggesting that the influence of LWD on pool formation changes with channel slope. Analysis of pool-forming mechanisms indicated that low-slope channels are less sensitive to LWD abundance because pools are formed by mechanisms other than LWD when LWD abundance is low. Size of LWD that formed pools increased with increasing channel width, but was not related to channel slope. Percent gravel (proportion of the bed in patches of gravel 16-64 mm in diameter) was best explained by channel slope and channel width, and there was no significant relationship between woody debris and percent gravel. A regression between median particle size of sediment on the stream bed and basal shear stress showed that the relationships among percent gravel, channel width, and channel slope are adequately explained by the channel\u27s capacity to transport particles of various size

Process-based principles for restoring river ecosystems

Process-based restoration aims to re-establish natural rates and magnitudes of physical, chemical, and biological processes that sustain river and floodplain ecosystems, thereby moving ecosystem conditions (physical, chemical, and biological) into the range of natural potential conditions at any site. Ecosystem conditions at any site are governed by hierarchical regional, watershed, and reach-scale processes, identifying restoration actions that are necessary to restore ecosystem function should include analyses that answer two main questions: (1) How have changes in riverine habitats affected biota?, and (2) What are the ultimate causes of changes in riverine habitats? Answers to these questions identify habitat types or areas that are most in need of restoration or will contribute most to biological recovery, as well as the causes of degradation that must be addressed to achieve restoration goals. Watershed analyses therefore include assessments of processes controlling hydrologic and sediment regimes, floodplain and aquatic habitat dynamics, and riparian and aquatic biota. Four process-based principles help guide river restoration toward sustainable actions: (1) address root causes of degradation, (2) make sure actions are consistent with the physical and biological potential of the site, (3) the scale of restoration should match the scale of environmental problems, and (4) restoration actions should have clearly articulated expected outcomes for ecosystem dynamics. Applying these principles will help avoid common pitfalls in river restoration, such as creating habitat types that are outside the range of a site’s natural potential, attempting to build static habitats in dynamic environments, or constructing habitat features that are ultimately overwhelmed by untreated system drivers

A new measure of longitudinal connectivity for stream networks

Habitat connectivity is a central factor in shaping aquatic biological communities, but few tools exist to describe and quantify this attribute at a network scale in riverine systems. Here, we develop a new index to quantify longitudinal connectivity of river networks based on the expected probability of an organism being able to move freely between two random points of the network. We apply this index to two fish life histories and evaluate the effects of the number, passability, and placement of barriers on river network connectivity through the use of simulated dendritic ecological networks. We then extend the index to a real world dendritic river system in Newfoundland, Canada. Our results indicate that connectivity in river systems, as represented by our index, is most impacted by the first few barriers added to the system. This is in contrast to terrestrial systems, which are more resilient to low levels of connectivity. The results show a curvilinear relationship between barrier passability and structural connectivity. This suggests that an incremental improvement in passability would result in a greater improvement to river network connectivity for more permeable barriers than for less permeable barriers. Our analysis of the index in simulated and real river networks also showed that barrier placement played an important role in connectivity. Not surprisingly, barriers located near the river mouth have the greatest impact on fish with diadromous life histories while those located near the center of the river network have the most impact on fish with potadromous life histories. The proposed index is conceptually simple and sufficiently flexible to deal with variations in river structure and biological communities. The index will enable researchers to account for connectivity in habitat studies and will also allow resource managers to characterize watersheds, assess cumulative impacts of multiple barriers and determine priorities for restoration