Climate Change Impacts on Aquatic Ecosystems in PNW

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Detailed Description

This webinar was held as a part of the Climate Change Science and Management Webinar Series, a partnership between the USGS National Climate Change and Wildlife Science Center and the FWS National Conservation Training Center. Webinar Description: Trout and salmon populations, which play a critical role in many ecosystems and economies, have dramatically declined in the Pacific Northwest (PNW) due to habitat degradation and fragmentation and introductions of invasive species, and are expected to be further impacted by future climate change. Understanding how climate change will influence the abundance, distribution, genetic diversity, and value of these native fish species is crucial for their management and recovery. This project used modeling techniques to study how climate change might affect freshwater habitats of key trout and salmon species throughout the PNW. The goal of the study was to develop and provide novel tools that will help managers predict and respond to potential climate change induced impacts on habitats, populations, and economies.


Date Taken:

Length: 01:07:22

Location Taken: Reston, VA, US


Ashley Fortune Isham: Good afternoon from
the U.S. Fish and Wildlife Service's National

Conservation Training Center in Shepherdstown,
West Virginia.

My name is Ashley Fortune Isham.

I would like to welcome you to our webinar
series held in partnership with the U.S. Geological

Survey's National Climate Change and Wildlife
Science Center.

The NCCWSC Climate Change Science and Management
webinar series highlights their sponsored

science projects related to climate change
impacts and adaptation.

It aims to increase awareness and inform participants
like you, about potential and predicted climate

change impact on fish and wildlife.

I'd like to welcome Shawn Carter to introduce
our speaker.


Shawn Carter: Thanks Ashley.

Today it's my pleasure to have Dr. Clint Muhlfeld
with us.

He's a Research Assistant Ecologist at the
USGS Northern Rocky Mountain Science Center

in Glacier National Park, and Research Assistant
Professor at the University of Montana's Flathead

Lake Biological Station.

Clint's involved with numerous interdisciplinary
ecological studies focused on a variety of

regional, national, and international aquatic
research issues of growing importance to both

society and biodiversity conservation.

His applied research aims to assess the threat
of invasive species, habitat loss, and climate

change on native aquatic species and habitats
in the Rocky Mountains of the U.S. and Canada

in the Pacific Northwest.

And today he's going to be talking about some
of his work.

So it's my pleasure to introduce Clint, and
it's over to you.

Clint Muhlfeld: Thank you so much, Shawn.

It's my pleasure to talk to you today about
our climate change research in the northern

Rockies and the Pacific Northwest.

I changed the title of my talk today to include
other biota besides salmonids because we're

doing a lot of high alpine research on rare
bugs below melting glaciers which I'll also


So the title of my talk today is, "Predicting
Climate Change Impacts on Aquatic Ecosystems

across the Pacific Northwest."

We know that climate change has impacted every
centimeter of the Earth, and especially, in

the western United States.

It's no exception here.

This landscape is undergoing tremendous change
in the thermal and hydrologic nature of stream

and lake environments.

And so the goal of our research is to really
provide tools and a good understanding of

how climate change may or may not impact different
species, how these impacts may be realized

at different scales, so we can predict and
then manage for these potential outcomes into

the future to build resiliency and adaptive
capacity for aquatic ecosystems.

Specifically a lot of our research has focused
on how hydrologic, thermal, and habitat change

has already influenced and may influence native
trout and salmon in the Pacific Northwest.

We're going to talk today about applying new
techniques that we've developed for combining

climate data with fine scaled vulnerability
assessments using genetic data, habitat analyses,

and wrapping this up to understand more holistically
these processes and how they affect species

for adaptive management and conservation.

Understanding how climate change may impact
aquatic ecosystems is obviously a major priority

for conservation management.

Changes in species ecology associated with
climate change has been documented and predicted

for a broad range of organisms, especially

Now, salmonid fish may be at particular risk
of climate warming because they're ectothermic.

They are cold water dependent.

They have a really narrow thermal range.

Their life history events are adapted to the
timing and magnitude of stream flow events.

And their dispersal patterns are restricted
to stream networks.

They've really nowhere to go.

Moreover, they have enormous economic, ecological,
and cultural value.

I'm going to start the story today at the
top of the continent.

It's the head waters or the water storage
or water tower of the Columbia Basin system.

It's called the "Crown of the Continent."

This is one of the most biodiverse and ecologically
intact systems in North America.

It's the convergence zone of four bioclimatic
regions converging on the narrowest point

along the Rocky Mountain chain.

With waters flowing to the Hudson, Atlantic,
and Pacific Oceans.

It's clearly the water tower of the continent.

We've been trying to understand the effects
of these warming impacts across these landscapes,

starting where the glaciers originate up in
Glacier National Park and understanding how

those aquatic communities are impacted immediately
below these melting and disappearing glaciers

understanding these impacts all along the
continuum, down to these valley bottoms where

the fish roam, where there's a host of biodiversity,
not only within the surface water of channels

but out into the flood plain zones where there's
a host of other organisms that are...some

aren't even described.

This area provides really complex cold and
clean areas for growth, survival and persistence

of a variety of species.

It's relatively intact and the water quality
is impeccable.

It's very cold, nutrient poor, and again,
this is the water that originates at the apex

of the continent and flows downstream providing
oxygen and really cold water for fish to spawn

in, grow, and survive in.

Today, I'm going to be talking to you about
the impacts of climate change on trout populations

in the headwaters of the basin, and then I'm
going to move downstream and talk about some

of our vulnerability work on salmon and steelhead
populations as well.

Here, in the top of the continent, in the
top of the Pacific Northwest, it's considered

a range wide and regional stronghold for a
variety of species that have survived cataclysmic

changes to the environment, such as wildfire,
floods, glaciation, et cetera, for at least

12,000 years.

We have the westslope cutthroat trout, these
rare stoneflies existing below these melting

glaciers in the high country and threatened
bull trout, which are listed under the ESA.

The bull trout is a charismatic megafauna
of the aquatic realm.

It's an apex predator.

It requires large connections of impact habitats
to complete its life history.

It migrates.

It's essentially an inland salmon.

It migrates 250 kilometers right back to the
stream they are born in.

The juveniles rear one to four years before
emigrating out to the main stream where they

grow to maturity to complete their life's

These guys are great indicators of aquatic
health, because not only do they require intact

and connections of habitats, but they also
have the coldest water requirement of any

salmonid species in the Pacific Northwest.

Similarly, westslope cutthroat trout are an
excellent indicator species in the face of

warming climate.

Unlike bull trout that spawn in the fall,
they're spring spawners, so they're using

high flows to ascend the stream network back
to their native streams.

They're spawning in a little bit higher gradient
higher up in the watershed system than bull


The embryos incubate in the stream gravels
into the summer months before they emerge.

Just like the bull trout they exhibit migratory
life histories as well as resident life histories

where they remain in their stream their entire

These salmonids have adapted to a changing
climate for at least 12,000 years.

When the glaciers were receding, these species
have invaded and colonized these areas for

many, many different times throughout our
geologic history.

At the end of the last glacial period, the
Wisconsin, we've seen bull trout and cutthroat

occupying a variety of habitats.

During the colder periods it's likely that
these populations resided more in the valley


These were the sources for connectivity and
dispersal, and the headwaters were more like


When we had periods of extreme warming, for
example, seven to nine thousand years ago,

it's likely that those valley bottoms were
the sinks and the sources were the headwaters,

because these trout had to retreat to these
colder stream networks located in the headwater


My point here is that these species have adapted
to persist under a changing climate for thousands

and thousands of years before humans were
on the landscape.

However, over the past century and a half
salmonid populations and a lot of other aquatic

biota have declined dramatically, largely
due to habitat loss, degradation, fragmentation,

invasive species resulting in competition
predation, invasive hybridization, disease,

and parasites.

It's the combination of these existing stressors
and the exacerbating impacts of climate warming,

which we're all concerned about, to build
resiliency in our native trout and salmon

populations throughout the Pacific Northwest.

Understanding the past and how as a prelude
to the future is really key to understanding

the impacts of climate warming on aquatic

Just looking at real data over the last 100
years, we looked at air temperature trends

in Western Montana, and we found that over
that record a loss of about a month of extremely

cold days and a three fold increase in the
number of hot days.

The kicker here was the Northern Rockies.

You think of this area as a refugium from
climate because it's high and cold and there's

a lot of snow and glacial masses, but these
air temperature trends were tracking the global

trend of increasing air temperatures.

The main point here is that we're warming
at two to three times the rate of the global


This landscape is undergoing dramatic change.

The warmer air temperatures are decreasing
our snowpack and our glacial masses are receding.

We're seeing increasing disturbance events
such as wild fires throughout the West.

These changes are altering the hydrologic
regimes of our stream and lake networks.

Overall, we're seeing a decline in stream
flows across the Pacific Northwest and the

Northern Rockies.

Several recent studies, shown here, have shown
that the annual discharges had declined over

the past several decades.

These flow regimes are shifting and changing.

Here's an example of the Flathead river where
positive values indicate increasing flows,

negative values indicate decreasing flows.

As you can see here, since 1958 on the shoulder
months of the winter period, we're seeing

the snow turn to rain.

We're seeing increase in fall and winter fawning
mostly on the shoulder months of the winter.

We're seeing an earlier spring freshet, in
general, about two to three weeks earlier.

That's leading to reduction in stream flows
during the summer months.

Here is a depiction of the hydrograph.

We see high flows in the spring.

We're seeing a shift to the left.

A decrease in terms of the magnitude.

Here is a spike in the fall.

It shows a fall flooding event that nearly
matched the preceding high flow associated

with the runoff.

Summer discharges are declining as I mentioned
before, throughout several USGS gage stations

in the Western United States namely in the
Pacific Northwest.

That's a general statement.

There are different changes elsewhere but,
in general, stream flows have declined.

Associated with that, temperatures are also

So we've seen a steady increase in water temperatures
across these stream networks for the past

several decades.

Perhaps, most iconic about the combining fact
that changes in flow and temperature and melting

snow masses is the melting glaciers in Glacier
National Park.

It's kind of the poster child of climate change.

At the last little ice age in 1850, there
was approximately a 150 glaciers on the landscape.

Glacier's losing its glaciers.

Now, there's only 25 named glaciers in Glacier
National Park.

The most conservative climate change estimates
show that all these glaciers will be gone

by 2030.

Glacier Park will no longer have its glaciers
by 2030 based on the best available science.

We're trying to understand these impacts across
these landscapes at different scales.

We're setting up a lot of different monitoring
networks for stream temperatures such as the

NorWeST Program in the Western United States.

We're trying to understand how stream temperature
is responding and how these ectothermic organisms

are responding to a changing temperature and
flow regime.

This example here shows our stream networks
and the head waters of the basin where we

have nearly 950 sites.

We're developing both seasonal and daily temperature
models to understand impacts on species over

different scales.

These include covariates such as land cover,
ground water influences, elevation, and glacier

and lake effects.

Scale matters when understanding temperature
responses over large and small areas throughout

the landscape.

Landscape models are really important to understanding
patterns and processes over large time and

space scales.

They're really important for integrating these
changes into ecological and management issues

for scenario planning and adaptive management,
so scale definitely matters.

But time does as well.

That's commonly overlooked.

We substitute space for time in a lot of instances.

Whether that's right or wrong, we're trying
to understand more about the temporal dimensions

of climate change and the impact in aquatic

We can understand over core scales and develop
these monthly and seasonal models to understand

average conditions, how these systems are
changing, and link them with climate simulations

to predict where across broad landscapes this
change will occur.

But there's also a need for these fine scale
assessments of using daily models to then

link with daily models of climate change to
understand how species key components of the

life's history are responding, such as life
history traits in terms of shifting in the

timing of spawning, fry emergence, growing
days and incubation days.

I believe that these different scales, these
temporal scales are complementary in understanding

the impact of climate warming on the thermal
dynamics and response of the species.

Here you can see our stream temperature projections
for August compared from the baseline to an

RCP 4.5, which is kind of a conservative,
middle of the road climate change forecast.

As you can see here, we can understand and
predict down to 30 meters, actually, potential

stream temperature changes across the networks.

We can then understand how critical thresholds
may be exceeded under different climate warming


We can also use these data to understand the
relative change across these landscapes, so

it's not just about the threshold, because
of what areas are going to change the most

over a given amount of time.

As you can see here, the lower valley bottom,
the major forks of the Flathead are predicted

to change the most over the next several decades.

Then we can move to a daily time step, as
shown here with Leslie Jones' work, where

she's developed these seasonal based models.

Now we're going to a daily time step, the
real data.

The empirical data are shown here and the
black circles show our predictions.

As you can see, they match pretty well.

Then we can link these daily time step climate
simulation modeling data with key components

of life history and development of trout and
other aquatic organisms in the system.

One way we've done that is to apply to critical
habitat for bull trout in this example.

We've looked at both critical foraging, migrating,
and overwintering habitat in the main rivers.

Then these key spawning and rearing areas,
where they go right back to spawn and the

juveniles rear in.

This paper came out this year, and what we
found is we use our stream temperature models

to predict stream temperatures across these
different types of habitat.

What we've found is that bull trout really
occupy the very coldest places of the landscape.

We can then use these different temperature
thresholds to then understand and predict

better how these habitats are going to change
into the future, so we can inform management.

In this case, if you increase, under this
model scenario, if you increase the stream

temperatures one degree, we can expect more
loss of habitat in these critical river corridors

that they use, especially during the summer
months, to ascend and spawn in their native


Then we can take that out over different time

We can then scale up to the scale of the crown.

We've done that by looking at critical thresholds,
such as 11 degrees, and then understand how

that's going to potentially impact bull trout
in the upper Kootenai system, in the Flathead

system, and then over in the Hudson as well,
the south Saskatchewan.

And then look at the relative change across
the landscape to then be able to prepare managers

where we're going to see this change the most
over the coming decades.

Obviously, with these analyses, high elevations,
northern latitudes, and groundwater in glacial

influence reaches are going to be really important.

We're seeing a lot of warming in the lower
elevations, in the lower latitudes.

These areas in the northern regions, in the
high elevations, are going to provide more

thermal refugia.

But, at the local level there's still spatial
heterogeneity going on.

We've been tracking bull trout to their known
spawning areas and what we've found, over

time, is these unconfined alluvial valley
reaches are really important for bull trout


At the reach scale, they're going back to
these alluvial valley bottoms where there's

a lot of groundwater and surface water interaction.

There's, essentially, huge upwelling zones
providing really cold temperatures in the

summer and nutrients and well oxygenated water
for the embryos to survive in.

We've set up temperature sensors throughout
the flood plain and into the main channel.

As you can see here, there's a great degree
of diurnal temperature fluctuations in these

bull trout spawning areas elsewhere.

But you can see here, there's groundwater

On an average, these areas are almost two
degrees colder during the summer months.

These are likely areas that are going to be
thermal refugia in a warming climate.

However, these areas, because they're unconsolidated
substrates, because they're multi channel

habitats, the incidence of winter flooding
may scour these reds.

That's another concern, into the future, that
we need to learn more about.

It's not only about the temperature.

It's about the flow too.

If they're building these nests in areas that
are susceptible to scouring effects associated

with fall and winter flooding, like I showed
you before, they could be vulnerable to those

impacts other than temperature alone.

We've been trying to understand not only how
contemporary patterns are influenced by climate,

and other human impacts, but how can we use
the past as a prelude to the future.

Can we use real data to then understand the
relative influence of climatic variation on

fish populations, in terms of abundance, distribution,
genetic diversity, and phenology, and then

build that into our climate projections so
we can more accurately forecast climate effects

into the future?

We just wrote a paper, a few years ago, focused
on Rocky Mountain trout, using real data.

Managers have been collecting fish population
data for decades.

Can we go into the archives and learn about
the relative influence of climate and other

human induced stressors on fish populations?

One example of that is our recent paper entitled,
"Invasive hybridization in a threatened species

is accelerated by climate change."

This is the westslope cutthroat trout here.

Like all other 12 extinct cutthroat trout
species, hybridization is clearly the leading

factor contributing to the decline of genetically
pure populations.

We need to figure out how climate might trigger
expansion of hybridization in nature.

Hybridization, unlike a mule, where they're

Hybrids produce hybrids.

Hybridization spreads and eventually you might
lose the genomic integrity of the species.

That's really critical for conservation in
the face of climate change because those locally

adapted genes and gene complexes are a link
to these locally adapted traits which have

enabled these fish to adapt and persist in
a changing climate.

Once hybridization occurs, it breaks down
those key linkages between the genes and their

adaptive traits, or phenologies, on the landscape.

With that, we might see their ability to adapt
and persist greatly diminished in the face

of climate change.

Building in the time component was really
key, in this study, to understand how hybridization

might spread in the face of climate change.

What we did is we used temporal genetics data.

Managers collected genetic data, back in the
late 60s, early 70s, and into the early 80s.

We used that to then resample areas in the
2000s to see if there's a change in hybridization.

We found hybridization dramatically spread
over just a few decades.

Despite, up until 1969, preceding these data
right here, there was over 20 million rainbows

stocked into the system.

These are non native introduced rainbow trout.

There was 20 million stocked in the system.

The only spot in the system, that we know
of, that had high proportions of rainbow trout

hybridization occurred in the lower valley

This population here was essentially a time
bomb waiting to go off under the right environmental


What we did is we resampled those areas.

We found hybridization spread in nine of the
18 previously non hybridized populations.

Then we took a snapshot to look at the genetic
integrity across the entire spatial extent

of the stream network.

We found this genotypic gradient with a lot
of hybridization occurring in the valley bottom

and a reduction in hybridization as you move
away from the source.

We found, in some of these peripheral populations
that we looked at...we actually used genetic

techniques and paternity analysis to see if
hybridization effects fitness in nature.

What we found is as you increase the amount
of non native rainbow trout genes in female

trout, in this example, in cutthroat trout,
you see a dramatic reduction in fitness.

With up to 20 percent non native genetic admixture,
or hybridization, with rainbow trout, we found

nearly 50 percent reduction in fitness.

In the face of climate change, if there's
a signal here, we can expect the resiliency

and the adaptive capacity of cutthroat trout
to be greatly reduced in a warming world.

We linked this with our high resolution stream
temperature models, and then data from NASA,

to reconstruct the invasion processes and
the spread of hybridization over this time


What we found is hybridization basically spreading
into areas with reduced spring precipitation.

In general, the rainbows are spawning as flows
increase in the spring and cutthroat are spawning

on the descending limb or when flows are declining
in the spring.

What we think happened here is these high
flows that we saw for decades kind of precluded

rainbows from pioneering out into the river

They kind of kept them abated because they're
spawning as flows increase so those scour

effects might wash away their nests, they
might wash away their fry.

They kind of prevented hybridization from

Again, 20 million rainbows were planted in
the valley until 1969, until this happened.

What we saw was a period of extreme drought,
in the early 2000s, and a reduction in spring


This was likely a window of opportunity through
which hybridization spread massively in the

system, irreversibly corrupting the native
genomes that have evolved over millennia in

the system.

To a lesser degree, stream temperature played
a role as well.

Rainbows typically have a little bit higher
tolerance for maximum temperatures.

We did find a correlation between increasing
stream temperatures and the presence and the

amount of hybridization.

These effects were realized in both our spatial
models and our temporal models.

I want to underscore here that the sources
combined with the climatic variables were

really driving the spread of hybridization

As you moved away from the source vein, incidents
of hybridization decreased.

But it's the sources persisting on the landscape
which then radiate out and hybridize and irreversibly

corrupt these native genomes.

We've showed this in a recent paper that's
actually coming out tomorrow.

It showed, in a very cold stream, we've got
mean summer temperatures well less than 10

degrees in Langford Creek and a very hot stream...we
saw hybridization increase over time.

What we did is we looked at the population
dynamics using real data over several years.

We found that despite the very strong selection
against admixture, in both environments, hybridization

increased over time due to the continued dispersal
of rainbow trout from downstream source populations.

If these sources persist, climate alone won't
impede or prevent hybridization from occurring.

It's just a matter of time where you get these
dramatic changes in the environment, like

those periods of extreme drought, that are
conduits through which hybridization will

spread in nature.

It's a combination of these sources with the
climate that might lead to the eventual loss

of native cutthroat trout.

We're even studying effects of climate not
only in the valley bottoms, where there's

neighbor trout, but we're also studying them
in the headwater areas below these melting


There's a couple different aquatic invertebrates,
that are endemic to Glacier National Park,

that have been petitioned for listing under
the Endangered Species Act because of climate

change induced threats.

Unlike the polar bear that was listed, no
other stream invertebrates have been petitioned

except a couple in Glacier National Park.

We're trying to understand how the recession
of the glaciers, the changes in these streams

from perennial sources to more intermittent,
and the stream warming, is effecting these


It's squeeze play at the top of the continent.

There's nowhere to go.

These guys have been retreating upstream,
tracking these cold waters, as the glaciers


They're confined to these 500 meter reaches,
immediately below these melting glaciers,

that are highly susceptible to change as these
glaciers continue to recede.

Like I said earlier, all the glaciers are
predicted to be gone by 2030.

This is Lednia tumana.

Joe Giersch is an aquatic etymologist studying
these stream systems.

This is the first footage of this ESA candidate
species for listing because of climate warming.

We did a broad scale habitat analysis using

We found that the highest probability of occurrence
occurs in over 23 square kilometers of habitat

across Glacier Park.

If you take away the glaciers and the permanent
snow masses, we'll see an 81 percent potential

reduction in distribution.

This species is strongly linked to glaciers.

If the glaciers go, they're going to be highly
threatened with extinction.

There's another species too, the Zapada glacier.

We've found, using time series data collected
back in the 1960s, where this species was

confined to the Many Glacier area of Glacier
National Park.

This is in dew specimens.

We were able to kind of reconstruct where
people sampled this species back in the 1960s.

Then we resample these areas over the past
several years.

We found a massive range contraction of this
rare endemic invertebrate.

You can see here, these two glacial basins
within the Many Glacier system, you can see

large tracks of glacial masses with massive
recession over the past several decades.

During the study period, these glaciers receded
about 35 percent from 1960 to 2012.

Here's the historic distribution of the Zapada
glacier as we knew it.

We re sampled these areas using morphology
to identify the species, using DNA barcoding

to find these cryptic species at the nymph

Joe did this over several years and found
only one population remaining in their native

range in the Many Glacier system, way up at
the tippy top of the continent.

The summer temperatures increased over the
study period; glaciers decreased by 35 percent.

There's a strong correlation here between
the loss of glaciers and a range contraction

of this rare bug retreating in colder water.

Here's where we know they occur.

They're at the top of the continent.

There's really nowhere to go.

These might be some of the first species to
go under climate change.

We're not only studying how species respond
distributionally and over time and space,

but we want to gain an understanding, too,
of how their demography and genetic diversity

plays into it.

We worked with a variety of folks here, and
we recently developed a framework that combines

demographic and genetic factors to assess
population vulnerability in strained species.

My point here is that it's not all about distribution.

There's important components of persistence
we’ve got to think about.

We’ve got to think about abundance.

We’ve got to think about life history in

We’ve got to think about genetic diversity
which is the basis for evolution and adaptation

in the face of climate change.

We need to think about all these things when
we're thinking about vulnerability.

This is a framework that combines demography
and genetics to come up with different "demogenetic,"

we call it, indexes of population vulnerability.

What this allows managers to do is you can
put different resistant surfaces across a

stream network, and you can forecast out to
see how these changes in demography and genetic

diversity will be realized under different
climate change scenarios, or any kind of habitat

use or invasive species scenarios as well.

You can see here in Generation 0 we can show
the genetic and demographic integrity of these

populations, and then give managers a glimpse
at their future in terms of demography and

genetic health.

These are the kinds of things we need to build
in our climate change predictions to better

understand species' responses.

We've learned a lot at the top of the continent,
and we've been working on a grant with the

Northwest Climate Science Center that has
funded a lot of that work, as well as expanded

it out to the Pacific Northwest.

We're also working with a group lead by Gordon
Luikart from NASA, where we're scaling up

to the Pacific Northwest to predict climate
change vulnerabilities in salmon and in trout

across this landscape.

It's a huge landscape where these species
have a freshwater phase of growth and they're

migrating to the ocean to grow to maturity
just like the bull trout in the inland Rocky

Mountain region.

We wanted to not only look at patterns of
distribution, but look at patterns of genetic

diversity and how those relate to vulnerability.

Vulnerability is defined as the degree to
which a system is susceptible to adverse effects

of climate as a function of exposure, looking
at climate change, namely temperature and

flow in this case, sensitivity, looking at
habitat buffering potentials like the groundwater

influence areas that I showed you with bull
trout, and their adaptive capacity such as

genetic diversity and their ability to cope
with change.

We launched this study, first to focus on
bull trout to understand how climatic variation

influences both ecological and evolutionary

Very few studies have done this, have looked
at how climatic variation influences genetic

diversity across landscapes and over different
time scales.

We sampled 130 populations of bull trout throughout
the Pacific Northwest to test whether patterns

of genetic diversity were related to climatic

We then determined whether bull trout genetic
diversity was related to climate vulnerability

at the watershed scale which we projected
into the 2040 and using existing habitat complexity

data as well.

Here's an example of how we can look at the
relative rankings of climate and habitat and

genetic variables for watersheds occupied
by bull trout.

Here you can see that summer temperature,
winter flood frequency, valley bottom habitats,

those alluvial valleys I told you about, and
allelic richness, genetic diversity here.

You can see there's a strong gradient in genetic
diversity as you progress up the system.

Areas in the lower basin, they're warmer,
on the fringe of the distribution, have less

genetic diversity or allelic richness in this

As you move up into the Columbia headwaters,
there's a strong pattern of increased genetic


Was this related to these patterns of landscape
change in terms of both climate and habitat?

You can see here after accounting for the
spatial pattern of this genetic diversity

from down in the lower Columbia to the Headwaters
with linear mix models, we found that allelic

richness in bull trout populations was positively
related to habitat patch size and complexity

and negatively related to maximum temperatures
and the frequency of winter flooding.

There's a very strong correlation with genetic
diversity and these climatic and habitat variables

across the scale of the Pacific Northwest
in terms of bull trout.

When we look at vulnerability in terms of
exposure to temperature and flow plus the

habitat buffering effects of these alluvial
valley bottoms, we found that the average

allelic richness was strongly correlated with
those variables.

We can anticipate in a future climate scenario
that as things warm, these flows change, we

might see their genetic diversity change still.

What was most of concern here is that we found
in areas that are most vulnerable to change

currently, are the areas with the least amount
of genetic diversity.

We can expect that as climate continues we'll
see inbreeding effects, potentially, and the

loss of adaptive capacity, potentially.

We're also expanding this work to look at
salmon and steelhead as well.

I just wanted to give you an understanding
here of the scale we're dealing with both

winter run and summer populations of steelhead.

Alisa Wade and Brian Hand are working hard
on this analysis now.

We're also adding bull trout to the mix for
this vulnerability assessment across the Pacific


Looking at patterns of genetic diversity and
how those correlate with climatic features.

In the case of steelhead, we looked at these
major evolutionary significant groups to see

if there was a correlation with climatic variation
and genetic diversity.

We did find one.

We found that winter precipitation, in this
example, was strongly related to patterns

of genetic differentiation.

So there's a strong relationship between climatic
variation and these patterns of genetic diversity

in steelhead populations as well.

What we're doing is we're using vulnerability
analyses to then look at how changes that

are built on these empirical relationships,
built on our hypotheses, built on real data

and published data.

They're all hypotheses.

All these vulnerabilities assessments are
hypotheses driven.

But we know some of the things that are strong
drivers of change like thermally suitable

habitat, like run off patterns, these valley
bottoms, land use, critical habitat, and building

in other things than just changes in occurrence
or distribution, building in local abundance

such as red trouts.

We've collected tons of this data throughout
these networks and combining them with patterns

of genetic diversity, as I’ve discussed,
as well.

This is our model for steelhead.

We're doing this for each species across the
Pacific Northwest.

We can look at vulnerability in a lot of different

There's no really right or wrong way to do

But in this case that Alisa provided, we looked
at exposure in terms of changes in temperature

and flow, so we have a spatially explicit
temperature model that's linked to a flow

model, VIC, to then predict that the watershed
scale, the vulnerability of different habitats

now and into the future.

We have habitat predictions across the network.

We also are building in patterns of demography
and genetics and understanding how these are

going to change into the future.

What it comes down to, and don't get caught
up in this huge mess over here, these elements

that we're including in vulnerability assessments
greatly dictate the outcome.

From these simple models that have been predicted
or developed, we have exposure in habitat

equals vulnerability.

Here we're arguing that demography and genetics
that are critical components of persistence,

need to be built into these vulnerability
assessments as well, and genetics, especially,

where we find strong linkages.

As you can see here, if you build in demography
compared to the simple approach verses genetics,

you're going to get different answers depending
on what you're looking at.

Understanding the real patterns in space and
time, building that into these vulnerability

in assessments, and then doing sensitivity
analyses, looking at how climate variation

might be sensitive to these changes as well
as the different components of the vulnerability


Finally, I wanted to let you know about a
new project funded by the USGS in the Rockies

where we're moving beyond the space for time
models, where we're looking at that other

temporal dimension that's so critical to look
at in terms of determining the relative influence

of climate variation on fish populations.

We're looking at using these high resolution
daily stream temperature models, linking them

up with real data that have been collected
from the crown of the continent up in Banff

and Jasper National Parks, all the way down
through Glacier Park, down to Yellowstone,

down in Wyoming, into Southern Colorado where
we can quantify these relationships between

climatic variation and demography and genetic

Then we can look at how this change influences
assemblages and the non-native and native

species interactions over space and time.

To summarize, we've entered a new realm of
disequilibrium in the 21st century.

Our predictions show that these habitats will
become more and more variable and shift.

Some will decline or become intermittent.

Many populations will adapt and track.

Others won't.

Combined with these existing stressors, many
of these populations are already depressed

and already have reduced resiliency in the
face of climate.

Conservation needs will be real daunting and
informed management is more crucial than ever

in this changing world.

But I'd argue that we have the tools necessary
right now.

Maybe not all of them, but we do have some.

In many cases, it's back to the basics for
informed decision making because management

decisions now will have enormous effects on
the amount of native aquatic biodiversity

a century from now.

We're on the critical point of conserving
these species for future generations.

As Wayne Gretzky says, we've all probably
seen this slide, “skates where the puck

is going to be, not where it's been”.

We need to look over broader time and space
scales to understand species' responses for

adaptive management because we're going to
miss 100 percent of the shots you don't take.

In the face of uncertainty, managers are going
to have to make difficult decisions to try

to keep some of these organisms on the landscape
for future generations.

We can do that through an adaptive framework
where we're constantly identifying and prioritizing

and learning about our different management
impacts to get to our goal of species conservation.

A lot of this is already occurring on the
landscape, so I would argue it's back to the

basics with a lot of things that we can deal
with existing stressors that humans have induced

on the landscape over the last century.

We're restoring flows and temperatures at
the major hydroelectric dams.

We're restoring connectivity like fish passage
ladders or removing dams entirely, dealing

with invasives when they get in stream networks.

In this study we showed that if you get on
it early enough in the stages of invasion,

you have a saving chance even with climate
warming on the horizon.

Maybe putting in barriers where you have populations
that are threatened, maybe opening them where

you don't.

These are complex trade offs that managers
need to make in this uncertain future translocating

species, thinking out of the box, looking
at areas where you're going to put them at

safeguards or refugia into the future, or
areas where you're reintroducing them into

formerly occupied habits.

And finally, protecting, restoring, and reconnecting
these critical habitats such as we've done

with working with our partners in Canada to
really fully understand how these relationships

interact with healthy environments and how
we can bring them back to provide healthy

ecosystems and habitat conditions for fish
populations and aquatic species to grow and

survive and persist in this changing future.

I always leave a talk with "Give fish a chance."

I think there's hope.

I want to thank you all for attending this
webinar today.

I'd be happy to take any questions.

Ashley: We have one.

It's from Donald.

It says, "What are some of the management
decisions that need to be considered, less

commodities extraction?"

Clint: I think that management decisions have

The paradigm's shifting.

I think in the past it's been reactionary.

In the case of native trout management, for
example, managers are reacting to annual events

like a collapsing stream bank and going out
and repairing that at a very small scale.

I think in the context of climate change,
managers are now thinking over broader landscapes

and over longer periods of time and understanding
that there's going to be winners and losers

in the equation, and being able to anticipate
the change and put the biggest bang for the

buck where you're going to get it into the

I showed some examples of management activities
that could bolster some fish populations into

the future here.

I think context matters.

It depends a lot on what the current situation
is in the system.

For example, in the case of cutthroat trout,
if a manager only has a few populations left

that are genetically pure and they're at high
risk of hybridization, a manager might have

to put in a temporary barrier to protect the
last remaining genetic strongholds for that

species so then they can work on invasive
species, habitat conditions, to try to re

found them to their historic habitats.

I think habitat management and protection
of riparian zones is going to be very important

into the future.

Monitoring those habitats over time is going
to be key because we have to evaluate change

and how we're manipulating the environment
to understand how species are responding and

is adaptive management working?

Space and time and context matters.

These are going to be difficult decisions
in the face of uncertainty, but I think in

a lot of cases it's back to the basics.

Like I showed in my first couple slides, these
fish have adapted to persist in a changing

climate over thousands of years.

More recently, they've declined dramatically
to the point they're greatly depressed and

the resiliency is greatly reduced.

We have to build back that resiliency in areas
where we can have hope.

I don't know if that answered that.

Ashley: We have another question from Donald,
and it was just referring to "Could hybridization

also be a survival strategy?"

Clint: I guess the verdict isn't out on that.

It can be.

Natural hybridization can lead to evolutionary
novelty, adaptive radiation, and can actually

create new species.

From an evolutionary standpoint, natural hybridization
is a key mechanism to promote persistence

of different characteristics and even create
new ones.

It's a lot different than anthropogenic hybridization,
human mediated, where we've translocated fish

in nearly every watershed in the United States.

In some cases, there's been irreversible change.

I would argue that invasive species are the
trump card for aquatic ecosystems.

We can do everything to build back habitat,
but hybridization is a one way street.

In the case of the cutthroat trout, that fitness
slide that I showed, that's the first study

that I'm aware of that has linked different
levels of non native genetic admixture with

performance on the landscape.

In this case, we looked at fitness in terms
of reproductive success, and we related that

to how hybridization may proceed or how it
might increase in individuals.

We found a strong negative effect there.

We found out breeding depression occurring
where anthropogenic hybridization is occurring

in native trout.

Over time, however, will those deleterious
alleles or genes get purged and recombination

take place and fitness will improve?

The verdict's not out yet.

I would argue though is that if you look across
the entire range of all these cutthroat sub

species across the Western United States,
hybridization, genetic in aggression is by

far the leading threat and has dramatically
declined the genetic distribution of cutthroat.

In the case of westslope cutthroat, we only
know of about less than 10 percent of their

historic distribution.

Now it contains non hybridized populations.

Again, those unique genes and gene complexes
are linked to those adapted traits that allow

these species to persist.

Hybridization occurs it jumbles them up.

Ashley: And then a follow up with that.

“Has there been an effort to remove the
invasive species in the hybridized zone to

tip the balance back in favor of the cutthroat,
despite conditions favoring the rainbows?”

Clint: That's a great question.

There's only a couple examples in open connected
stream systems one in Idaho and one in the


I've been a part of the one in the Flathead
when we first discovered hybrids in the stream


Montana Fish, Wildlife & Parks at the time,
they have a dual mission providing recreational

opportunities as well as protecting native

We found hybridization was increasing in this
interconnected stream network.

In the face of uncertainty, the managers went
out, and we surgically implanted transmitters

into the body cavities of these hybrids.

They led us to the hybrid source population.

It's like the Judas fish approach.

We identified where these hybrid sources were
on the landscape, and the managers, in the

early stages of invasion, got on it and started
suppressing and attempting to eradicate these


Over time, over the last decade or so, we've
seen a dramatic reduction in the number of

hybrids at these sites, and we've seen a slowing
of the spread of hybridization and a reduction

in the percent genetic admixture in cutthroat
populations that we've been monitoring in

the system.

In this case, it worked or it's working even
with climate change because managers got on

it in the early stages.

Ashley: “How does your work dovetail into
or complement Dan Isaak's work with the US

Forest Service?”

Clint: We've worked with Dan and his group
on several projects.

One good example of how our research programs
are complementary is with Dan's temperature

sensor network that he set up all over the
Pacific Northwest, the NorWeST program.

That's been an amazing program, one, in my
opinion, for people to gain an understanding

of how climate change is affecting aquatic
habitats over broad scales, and even at local


So for one, gaining a better understanding
has been key, and then understanding that

change by instituting and setting up a temperature
sensor network across this broad landscape

is very key for monitoring how warming impacts
are occurring over these broad scales.

So that's been very important.

We can link that to great models to predict
occurrence and changes in species distributions,

for example, into the future.

That's going to be very key for management.

An example of how our approaches with the
daily models are complementary is that we

can again look at different scales of fish
performance, for example.

Not only these seasonal means and averages
to look at changes over these scales, but

we can actually link daily time step simulations
with responses of fish populations, such as

changes in growing days or emergence or the
timing of spawning.

I think that these different temperature modeling
approaches are actually very complementary

in a lot of cases.

Ashley: A couple more questions.

One is from Elise and it says, "It's not uncommon
to have one endangered fish species move into

another endangered fish species' habitat where
it previously did not occur.

Do you have any thoughts about managing this?"

Clint: [laughs] Is that Alisa Wade?

Ashley: Kelley.

Clint: Oh, OK, I'm sorry.

If an endangered species moved into another
endangered species, so if there was a shift,

how would we manage that?

Is that the question?

Ashley: Yes, I think so.

Clint: Well, I'm not a manager.

I'm a researcher.

So what I would try to do is understand what's
driving those interactions.

I would say that if that's the case, that
would be an area where you'd probably want

to protect or conserve biodiversity, because
we've got two species that are now asympatric,

and if we're going to do adaptive management
on the landscape, you're going to benefit

two species.

If one species is negatively impacting one
another, again, we're going to have to go

back to "the context matters" and to understand
the relative distributions and abundances

and the genetic diversities of those species
across the landscape.

See where they overlap.

See where maybe one species might have a broader
range, the other doesn't, and try to develop

approaches to hang on to the one that's declining.

Again, I think my job is to provide data for

Those are difficult questions.

I'm really not familiar with that happening
on the landscape, although I could be wrong.

That's a tough question.

Those are difficult decisions.

If anyone has examples, I'd love to hear about

Ashley: Another question from Janelle.

It says, "Would you be able to address the
Jarbidge River population in light of your

climate change predictions?"

Clint: At the watershed metapopulation scale,

Right now, with the blue temperature and flow
model, we can look at the vulnerability of

those systems to change.

We also have genetic data from the Jarbidge

That was one of those populations that had
low levels of genetic diversity.

In the face of climate change in areas that
are already on the southern limit of the range,

such as that system, that might be an area
where adaptation is going to be even more


What we know now is that the genetic diversity
is at its lowest there.

I don't know if that answers your question
or not.

I would say that the peripheral populations
are important for evolution and climate warming.

The more we can learn about how those species
are under selection.

Those selection pressures are greatest at
those southern limits of the ranges.

If we can learn more about the adaptive capacity
and how certain regions of the genome are

linked to temperature and flow, we can better
understand how species elsewhere are going

to respond.

In the case of Jarbidge, we do have some data.

Again, it's at the watershed scale.

I would say that with Dan's temperature work
coming online soon, linking that with VIC,

you could probably get a better high resolution
analysis of the impacts in the Jarbidge system.

I would then add we've got abundance in genetic

You could then look at how those might change
into the future.

Ashley: Thank you.

We're running low on time.

We do have about four more questions.

I'm going to take up two right now.

"In your scaling up analysis, what do you
think would change in your assessment if you

considered other local characteristics, such
as stream temperature, over air temperature,

or flow gauged on that specific stream?"

Clint: I didn't catch the first part of that.

Ashley: “In your scaling up analysis, what
do you think would change in your assessments

if you considered other local characteristics?”

Clint: I guess the way I'd answer that is
that at the smaller scale, we've found that

the alluvial valley bottoms are going to provide
critical areas for thermal refugia.

Again, those are the areas with ground water,
hyporheic flow.

Those are the cold spots on the environment
now and likely into the future.

There's still a lot of things that we don't
know about those areas.

What I would say is that scaling up, we'd
want to be able to quantify where those areas

occur, so we can build them as covariates
into our models to better predict temperature


When you look at relationships of observed
temperature to expected, there's a strong

correlation there with our temperature models.

The extremes, those outliers, tend to be those
groundwater influenced areas.

I think if there's one area that we need to
learn more about, and build that understanding

into our modeling.

It's understanding those groundwater influences
and how those might change into the future.

Nagle, with the Forest Service, developed
an algorithm to predict that.

I didn't show it in my slideshow, but using
our daily stream temperature model and looking

at a groundwater site, it predicted again,
this is an algorithm we can apply to different

landscapes that site actually showed up right
in those alluvial valley bottom areas that

were predicted by our model.

We're trying to account for that in our stream
temperature models.

For flow, I would say the biggest demand right
now, or weaknesses, are that a lot of the

flow gauge stations are in large rivers.

We need to get a better understanding of what's
going on at the local scale in smaller order

streams to get a better understanding of how
flow influences fish populations, because

truly, flow is a master variable.

Ashley: Thank you.

Last question.

It says, "I noted with interest your description
of RCP 4.5 as a 'middle of the road climate


In contract, our PCIC climate specialist described
A2 and RCP 8.5 as 'roughly as business as

usual,' B1 and RCP 4.5 as 'roughly half the
emissions of business as usual,' and RCP 2.6

as 'aggressively optimistic greenhouse gas
reduction scenarios.'"

Do you care to comment?

Clint: Well, I'm not a climatologist, I'm
a fisheries ecologist, for one.

I can speak to that just in the case of our
work, using RCP data.

We compared RCP 4.5 to 8.5 predictions in
the crown ecosystem, which I showed you at

the beginning of our show, as well as the
climate vulnerability work that Alisa has

been working on.

We haven't seen a lot of differences in changes
in temperature and relative vulnerabilities

across these different scales.

But again, that's a broad statement from a
naive scientist that relies on my climatologist

to feed me those data to build into our biological

Ashley: Excellent.

Thank you, Clint.

And Shawn, did you have any closing remarks?

Shawn: I'm tempted to comment on that last
question, but in the interest of time, I will

say thank you very much, Clint.

It was an excellent presentation.

Clint: Well, thank you all.

It was a pleasure to be involved with the
webinar series.

I appreciate your time and attention.

It's been fun, thanks.