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

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 multispecies assessment of climate change threats to salmonids across their life cycle

During their life cycle, salmonids experience conditions in freshwater, estuarine, and marine habitats, exposing them to numerous climate change threats. The extent to which different species utilize different habitat types and habitat-specific climate change risks should result in differential overall vulnerability of these species to climate change, but most previous vulnerability assessments have focused only on particular life stages for particular species, hampering our ability to protect, restore stocks and their habitats to maximize species portfolios in river systems. We performed a life cycle-based risk assessment of climate change threats for nine species of salmonids (species within Oncorhynchus, Salvelinus, and Prosopium genera) inhabiting the Skagit River system, which is vulnerable to the panoply of climate impacts forecasted for the Pacific Northwest. The risk assessment integrated both species-specific intensity and exposure and incorporated uncertainty. We found that while climate change threats existed across all habitats inhabited by these species, the greatest threats to all species were associated with projected changes in the extremes of freshwater flow (high incubation flows, low summer flows). These results suggest that restoration strategies targeting restoration of floodplain function will be most effective for reducing the most serious threats for a broad portfolio of salmonids inhabiting the Skagit River, although other climate adaptation strategies may provide additional benefits to other suites of species

Influence of landscape and hydrological factors on Stream‐Air temperature relationships at regional scale

International audienceIdentifying the main controlling factors of the stream temperature (Tw) variability is important to target streams sensitive to climate and other drivers of change. The thermal sensitivity (TS), based on relationship between air temperature (Ta) and Tw, of a given stream can be used for quantifying the streams sensitivity to future climate change. This study aims to compare TS for a wide range of temperate streams located within a large French catchment (110,000 km2) using 4 years of hourly data (2008-2012) and to cluster stations sharing similar thermal variabilities and thereby identify environmental key drivers that modify TS at the regional scale. Two successive classifications were carried out: (a) first based on Ta-Tw relationship metrics including TS and (b) second to establish a link between a selection of environmental variables and clusters of stations. Based on weekly Ta-Tw relationships, the first classification identified four thermal regimes with differing annual Tw in terms of magnitude and amplitudes in comparison with Ta. The second classification, based on classification and regression tree method, succeeded to link each thermal regime to different environmental controlling factors. Streams influenced by both groundwater inflows and shading are the most moderated with the lowest TS and an annual amplitude of Tw around half of the annual amplitude of Ta. Inversely, stations located on large streams with a high distance from source and not (or slightly) influenced by groundwater inflows nor shading showed the highest TS, and so, they are very climate sensitive. These findings have implications for guiding river basin managers and other stakeholders in implementing thermal moderation measures in the context of a warming climate and global change