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2003
RIVER
RESCUERS
UM'S NEW RIVERINE SCIENCE CENTER
POISONED
HEARTS
ARSENIC EFFECTS ON CARDIOVASCULAR HEALTH
WATER
WIZARDRY
BIO STATION'S NEW FLOOD PLAIN MODEL
RIVERS
THAT TIME FORGOT
AN UNDISTURBED RUSSIAN WILDERNESS
SODIUM
SOLUTIONS
COALBED METHANE IN EASTERN MONTANA
HEAVY
METAL
SCIENTISTS STUDY IMPACT OF METALS ON MICROBES
COTTONWOOD
CONUNDRUM
MONTANA'S DISAPPEARING RIVER TREES
WATER
WARDENS
UM'S WATERSHED HEALTH CLINIC
TALLYING
TADPOLES
STUDYING MONTANA AMPHIBIANS
FISH
FINDERS
DNA IN WATER REVEALS LOCATION OF FISH
WET
AND WILD
A PRIMER ON MONTANA AQUATIC LIFE
WATER
THAT WAS
THE SECRETS OF GLACIAL LAKE MISSOULA
NEWS
TO USE
THE WEIRD LIFE CYCLE OF SWIMMER'S ITCH
BACKTALK
GIARDIA: A WATER DRINKER'S GUT-WRENCHING SURPRISE
A quick primer on Montana aquatic life
By GARY JAHRIG
Montanans love to boast of their state's pristine lakes and blue-ribbon rivers and streams.
And rightfully so. But how many residents of the Big Sky state actually know what lives beneath the surface of Montana's famous waters?
Lisa Eby does.
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Eby, an assistant professor of aquatic vertebrate ecology at UM's College of Forestry and Conservation, is an expert on fish. Eby, who holds a doctorate degree in aquatic ecology from Duke Univer-sity, came to UM a year ago to teach about and research aquatic life.
"I came here because I knew UM had a good program and it's such a great place to live," Eby says.She recently shared some of her knowledge by providing answers to some often asked questions about fish and plants in Montana's waters.
Q: Compared to other areas, are Montana waterways relatively
sterile or lush with life?
A: Compared with other areas of the United States, Montana's
waterways are very clear and pristine, which allows the native
trout species to thrive. But there is low diversity for freshwater
fishes. For example, the Clark Fork River has about 12 native
freshwater fish species, while rivers further east often have
between 50 to more than 200 native freshwater fish species.
The distribution of Montana's fish fauna is interesting because
of the Continental Divide, which has separated westward-flowing
and eastward-flowing waters for millions of years and has had
a major influence on the distribution of native fish in the state.
Although there are species that are found throughout the state,
the native fish communities in eastern and western Montana are
very different. Eastern Montana has more species than west of
the divide. There are both more families of fishes, as well
as more species within
families, such as minnows and suckers.
Q:
How do fish survive under the ice in winter?
A: Fish remove oxygen from the water as it flows across their
gills. In streams, many fish take refuge in pools during the
winter. In lakes, ice cover only becomes a problem if it lasts
a long time and is thick, separating the water from its source
of oxygen — the atmosphere. This results in
a decrease in oxygen concentration in the water. Fish
typically don't freeze under the ice as they have slightly
higher concentrations of ions (salinity) than water, and therefore,
have a lower freezing point than water. Fish that live in very
cold climates have different abilities to deal with freezing
temperatures. For example, some fish have blood that contains "antifreeze" compounds
that depress the freezing point of their body fluids and make
it possible for them to live in water that is colder than the
freezing point of most fish blood.
Q: How high up can fish species live in the mountains?
A: Fish can survive in the highest mountain lakes of Montana.
Originally some high-mountain lakes in Montana were without
fish because of barriers to movement such as waterfalls. Many
of these lakes and streams are nutrient poor and do not have
much food for the fish, resulting in very slow growth rates
and stunted populations. The stocking of some of these lakes
with hatchery fish can result in a large change in the aquatic
community and may be creating problems for several species
of amphibians that have historically reproduced in that area.
Q: What are the largest and smallest fish found in Montana?
A: There is a large amount of variation in size and growth
rate for fish depending on where they live. In western Montana,
the white sturgeon is probably the largest adult native fish
species. But in eastern Montana, paddlefish are the largest
fish. The smallest fish is difficult to determine because
many fishes are pretty small. For example, the brook stickleback
reaches only about 2 inches in length. And many fishes in
the minnow family — such as the fathead minnow and
the red belly dace — only grow to a few inches. Western
mosquitofish, a nonnative species often introduced to control
mosquito populations, reach only 1 to 2 inches.
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| Lisa Eby, assistant professor of aquatic vertebrate ecology. |
Q: What is the biggest threat to Montana's native fish species?
A: Some of the biggest threats to Montana's native fish include
fragmentation of habitat and the introduction of exotic species.
Many species of fish have large ranges and migrate between
areas where they reproduce, over- winter and forage. The
building of dams, roads and culverts can keep these fish from
reaching habitats that are necessary to complete their life
cycle. Exotic fishes are problematic because they can displace
native fish (out-compete or prey upon), hybridize (interbreed)
or bring in parasites and disease, resulting in declines
in native fish populations.
Q:
What is the most interesting Montana fish species?
A: I guess one of the most interesting fish that I have learned
about is the N. Redbelly dace-Finescale dace hybrid. These hybrids
have an unusual reproductive strategy called gynogenesis. The
hybrid dace are female clones with identical eggs. To reproduce,
the females must mate with a sexually reproducing related species
(Redbelly or Finescale dace) to stimulate egg development — even
though the genetic material is not incorporated into the offspring.
Q: Why are there so few aquatic-rooted plants in Montana lakes
and streams?
A: The physical and biological characteristics of the stream
and large lake systems (rocky bottoms, low productivity, stream
flows and ice scour) will keep plants from growing in the water.
But in other systems, such as wetlands, there is more sedimentation
and muddier bottoms for plant life to grow. There you will see
typical wetland plants such as sedges.
Q: What are the dominant plants that fuel lakes and streams?
A: The dominant plants are algae. In lakes, algae are consumed
by zooplankton, which are
then consumed by fish. In many streams, the production is
dominated by algae and bacteria attached to the bottom or
to rocks — what
some people think of as slime.
Q:
What is Montana's state fish?
A: The cutthroat trout (Oncorhynchus clarki).