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Good morning. What I’d like to talk about today are ideas, questions, and challenges of climate conservation planning for salmon.

This talk will focus on streams and rivers of the PNW. These rivers are the lifeblood of salmon, steelhead, trout and a host of other wonderful fish species in the region, and are fed by rain and snow that falls primarily during the fall and winter.

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But the temperature and precipitation projections for the PNW indicate that we might anticipate substantially warmer temperatures. While overall precipitation projections are within the bounds of historic variability, timing and type of precipitation will change.

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Warmer temperatures mean that precipitation that does fall in the winter in the PNW will increasingly fall as rain, instead of snow.

These peaks, for example, in the Cascade Range of Oregon capture snow during our winters, sustaining streamflows and water into the summer months, supporting water quality and fisheries like spring Chinook salmon, winter and summer steelhead, coho salmon, cutthroat trout, and a host of other fish species.

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As a result of these climate changes, PNW watersheds will likely experience increased water temperature, and shrinking areas of suitable thermal habitat for coldwater fish like salmon, in watersheds like the Willamette basin shown here, which is already stressed by high water temperatures. This spring we had a very strong run of spring Chinook salmon back to the Willamette, but a very large portion of the run perished in hot water due to metabolic stress and disease.

These figures are derived from the NorWeST dataset http://www.fs.fed.us/rm/boise/AWAE/projects/NorWeST.shtml

and show significant shrinkage of coldwater habitats (darker blue areas) over the next 60 years. These projections would suggest that the types of stresses salmon experienced last summer will be more common in the future.

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So what are people doing about this? Dan Isaak and colleagues published this paper in 2015, calling for steps to identify and delineate climate refugia for salmon. This idea definitely seems to strike a chord with people. We really want to think that maybe we can hang onto those things we value in the midst of what might be catastrophic change – it’s human nature. We’re drawn to the idea of refuge, of holdouts, of hanging on in the midst of adversity.

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Numerous news outlets have picked up the story of climate refugia for salmon and trout.

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Earlier this week (December 11, 2015) the New York Times featured this story. Clearly, the concept of climate refugia is one that resonates with a public that cares deeply about fish, and is concerned about the additional impacts that climate change may bring.

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But what is a climate refugium? One definition, by Morelli and her coauthors: Climate refugia are areas that are buffered from climate change effects relative to other areas so as to favor greater persistence of valued social, physical, and ecological resources.

The concept of climate refugia has its history in paleo-ecology, and the study of how the distribution of plants and animals have shifted with climate over time. The concept is now being extended into the future, as a way to anticipate the ability of populations to track shifting climates. One fundamental premise is that particularly in heterogeneous landscapes, some areas will be buffered from the changing regional climate, will change less slowly, or even in an opposite direction, from the prevailing conditions within a larger region. In the past, such areas have allowed populations of plants and animals to persist as relict or island populations as the surrounding landscape warmed or cooled.

The question that is being asked now, is how will this process look under future climates? Can refugia help populations persist?

These ideas have been relatively well developed in the terrestrial ecology literature, particularly for plants.

The recognition and protection of climate refugia has been proposed as a potential adaptation strategy that may be useful for protecting the biotic integrity of watersheds under a changing climate.

The idea of finding a refuge from adverse conditions has a huge innate appeal; we all seek refuge, stability in times of uncertainty and change, a home, a haven, a safe place.

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I want to clarify that I’m talking about refugia, and not refuges.

Refuges are short-term shelter from adverse conditions – like this small patch of cold water that is temporarily sheltering thermo-regulating juvenile steelhead trout escaping near-lethal temperatures that occur for a few hours each day during the hottest time of the year. A feature like this is a refuge –occurring at relatively fine spatial and temporal scales. Heterogeneity at this scale can be very important, but it’s not the scale of refugia. This talk is focused on large-scale refugia, operating on populations at evolutionary time scales. For highly mobile fish species like salmon with life histories that span ecosystems from the mountains to the sea and back again – refugia are the big areas of suitable habitat that maintain populations over longer time periods

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A lot of what we know about refugia we’ve learned by looking back in time. For example, in western North America (red box), areas not covered by the continental ice sheet (glacial refugia) allowed species to persist through periods of glaciation. Plant ecologists are very familiar with the way in which this process has influenced current distributional patterns.

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Examples can be found for fish, as well. For example, following glacial retreat and melting of the ice sheets, rainbow trout that had existed in climate refugia in the Columbia basin in southern Washington, and in the coast Queen Charlotte Islands were able to radiate and recolonize the newly exposed landmass and riverscape following ice retreat. Researchers like Waples and Tamkee have reconstructed these events through genetic analysis of rainbow trout lineages. Trout were able to recolonize out from these refugia to create distinct lineages in coastal vs inland rainbow that can be detected via patterns in genetic variation in rainbow trout today.

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That’s a very brief description of one example of the evolutionary history of salmon in the PNW.

This history is summarized very nicely in this overview graphic of evolutionary events in the history of Oncorhynchus from the time of speciation up until the present. Note the recolonization from glacial refugia here at the beginning of the Holocene.

What does this mean for the future?

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Some say we’re in a new epoch – the Anthropocene.

What will be the implications of this new climate, with new vegetation patterns, a rising and more acidic ocean, and new evolutionary pressures on salmon? What does this mean for salmon evolution?

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So far I’ve provided the background – the concept of climate refugia.

Now I’d like to shift to discussing what it means for climate adaptation planning. What are the uncertainties? Which are critical?

For the remainder of this talk I’ll discuss three arenas of uncertainty: the physical process side of climate and hydrology, the ecological arena and it’s host of uncertainties, and the human element – always a source of surprise and novelty.

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The first set of science needs, or uncertainties, pertain to our physical models and predictions of temperature and hydrology. The heat dynamics of freshwater rivers, lakes, and streams are part of the larger hydro-climatic system, and are tied to the oceanic, atmospheric, and terrestrial systems in which they are embedded. And we are increasingly understanding the patterns of heterogeneity in processes across these complex landscapes, and getting better at modeling and predicting energy regimes. But with regard to projecting climate effects on freshwater systems, there remain some pressing uncertainties.

The heat dynamics of freshwater rivers, lakes, and streams are part of the larger hydro-climatic system, and are tied to the oceanic, atmospheric, and terrestrial systems in which they are embedded.

And we are increasingly understanding the patterns of heterogeneity in processes across these complex landscapes, and getting better at modeling and predicting energy regimes. But with regard to projecting climate effects on freshwater systems, there remain some pressing uncertainties.

And not only will these individual processes change, in terms of magnitude or rate, but their relationships may change. For instance, the relationships among different aspects of the thermal regime may not be stationary, but may change under future flow and energy regimes. Many moving parts will change simultaneously and at different rates under global change, and we’ll need to be watching for those unexpected interactions.

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For example, at regional scales, thermal regimes of freshwaters are driven by interactions of climate, geology, and geography, as beautifully illustrated by the crowd-sourced temperature data and spatial stream network (SSN) modeling work of Dan Isaak and colleagues. But with climate change, not only will these individual processes change, in terms of magnitude or rate, but their relationships may change. For instance, the relationships among different aspects of the thermal regime may not be stationary, but may change under future flow and energy regimes. Many moving parts will change simultaneously and at different rates under global change, and we’ll need to be watching for those unexpected interactions. Dan will probably talk more about this in his talk later in this session.

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Within individual rivers, longitudinal profiles of water temperature, here illustrated using imagery collected by forward looking infrared, can show heterogeneity associated with differential exposure to solar radiation, water withdrawals, reservoirs, or groundwater influences.

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And at even finer scales, variation in annual thermal regimes – shown by these plots of temperature (y axis) over the annual cycle (1 yr on x axis) can occur in structurally complex alluvial rivers where groundwater, hyporheic flow, and surface waters mix to varying degrees in complex channels.

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These new tools and approaches are providing a whole new look at the spatial-temporal thermal regime of rivers; here illustrated by a study that combined continuous monitoring with remotely-sensed snapshots to model regimes over a larger spatial-temporal footprint. And soon we’ll have a pretty darn good picture of the thermal landscape in continuous time-space.

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Uncertainties and science needs apply not only to these thermal dynamics, but also to important shifts projected in the hydrologic regime.

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Another set of science needs, or uncertainties, have to do with getting our modeled relationships right. How do fish respond to temperature?

There are relationships we understand very well; for instance, this image shows a typical growth curve.

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But we know this is really better represented as a family of curves, varying with the amount of food available to the fish at a given temperature. So of course seldom is it just one thing that is influencing fish performance, and population dynamics. These curves are often established under controlled laboratory settings, with carefully controlled temperatures. What about fish responses to regimes, thermal histories, that vary over time and space?

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And we know that it’s not just summer water temperature maximums that matter to fish, though in many cases, those may matter most, but there are other aspects of the thermal regime, and different seasons, that are important too.

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What’s even harder to get a handle on are community interactions. This image shows a charismatic mega-predator, and it’s easy to see the effects of these predators, (and easy to place blame, if you can get past the adorable face), so they receive a fair amount of attention regarding their effects on salmon runs, but if I were to place a bet on what community interactions will be most significant for the future of salmon in our watershed, my money would be on the micro-biome – the bacteria, parasites, viruses. Sure, we may see some wacky things with the mega-competitors and predators, but how diseases and parasites change their interactions with salmon under future climate conditions is a really disconcerting unknown, and one that we shouldn’t ignore.

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In a study we conducted in Oregon coastal streams, we observed high rates of infestation with a parasitic nematode Neascus, particularly severe at higher water temperatures.

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We observed lower body condition, smaller smolt size, and lower overwinter survival associated with infestation rates. Histological examination of infested fish revealed numerous other pathogens and parasites were present, particularly from fish from warmer portions of the stream network.

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And there will be other constraints on salmon populations. In many current situations, we feel relatively confident about our understanding of limiting factors, bottlenecks, and other constraints on our salmon populations. But new constraints may emerge that we don’t have a good handle on.

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Similarly, the relationship of species to the environment isn’t static, nor is it homogenous across the landscape. We understand some aspects of the spatial pattern of local populations and adaptations to their environments, much less about how flexible these might be within the larger evolutionary niche – or event the bounds of that evolutionary niche. How far can we push salmon populations into a corner of this evolutionary niche before we’ve really constrained their ability to adapt and respond?

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And finally, understanding and predicting species responses to climate change may also be complicated by novel species interactions. I’m not used to pulling up white crappie and chinook salmon in the same seine haul, yet it happened to me recently. I love and am fascinated by such surprises, but in the big picture, such surprises may not be so delightful for the losers in these interactions.

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Humans are delightfully creative. And there are many examples of small scale – as in very small – efforts to increase thermal diversity and biocomplexity in streams and rivers to benefit salmon

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– but in order to support populations of salmon ranging over 100s of km, they will need to be part of much larger networks of cold water.

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Engineering and water management will also be a part of our climate adaptation strategy. How well will our management actions match the magnitude and scale of environmental change?

Adaptation actions could include water capture, storage, and distribution; groundwater pumping; species translocations and captive rearing; and a host of other activities – many of which are very small in magnitude or spatial extent compared to the magnitude of changes that we have imposed on aquatic systems, and that climate change will bring.

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So how do we pull it all together? On approach is to nest and link various scenario modeling approaches – tasks that many in this room are involved in, either from the temperature, flow, or population modeling perspectives, and increasingly we’re recognizing the need to pair our models with human systems modelers, economists, and optimization theorists. An example that’s emerging in the Snoqualmie Basin of WA is linking both physical, biological and social models using optimization approaches to identify and evaluate investment strategies for watershed restoration. Weighing temperature or fish outcomes against participant objectives, and values allows a more complete model of the salmon-human system.

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So the ecology is messy – we know that, and I used to think that the hydrologists had it so easy – they just have to deal with physical laws that are predictable and measurable. Yet there’s a lot we don’t know about the processes that will maintain refugia over the long term. What processes actually drive large scale stream temperature patterns, and how will these processes respond not only to climate change, but to the human responses to climate change. And of course I’m thinking about groundwater, and our management of various aspects of the water cycle. There will be calls for increased engineering solutions to capture and store water, to pump and move surface water and groundwater – these all have and will have huge implications for thermal regimes.

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And finally, at what spatial scales must these drivers be considered to maintain species within refugia?

Refined instrumentation, down-scaling, and modeling are providing the fine-scale resolution we need

What we further need is an understanding of the dispersal and connectivity needs of fish and how that will change with network shrinkage or changes in seasonal streamflows and temperature.

How big a patch is needed?? Is it this big (the blue sections of stream?)

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Is this big enough?

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Or this?

Knowing how much is ‘sufficient’, how much is needed to help ensure viability of coldwater fishes, won’t necessarily be easy to quantify, but agencies, water users, and other affected parties are demanding this answer.

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And will our actions be enough? How effective are the various small-scale actions that we are using to try to climate-proof our watersheds? We’ll need to put these effects into the context of projected climate changes to evaluate the long-term prognosis for fish in these watersheds.

This talk has highlighted the uncertainties and science needs. I’ve provided no new answers, and a host of questions.

These uncertainties need not delay anticipatory planning, but rather highlight the need for identification and communication of actions with high probabilities of success, and targeted research within an adaptive management framework.

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And I want to acknowledge up front that almost all of these ideas have sprung from conversations with plant and animal ecologists from the NPS and USFS, and further elaborated with colleagues in the EPA, USGS, NOAA, OSU, UW, and UC Berkeley.

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