watervulnerability

Chugach National Forest Watershed Vulnerability Assessment, Alaska Region (R10)
predicted at least on an occasional basis. It is certainly speculative, but the various species may already
have the genetic capacity to persist considering their past experience.
Along these lines, Bryant (2009) points out that the future Alaska climate may become more like British
Columbia, where the same salmonid species exist, or have existed, in abundance. In time, with the help of
straying or through selection, these species could be expected to exist or even flourish in Alaska under the
changed climate conditions. The only difference, Bryant notes, is that the evolution will need to occur
over a period of decades rather than hundreds or thousands of years.
Thus, the key to maintaining species of all sorts may simply be through the conservation of diverse
habitats and genetic stocks (Hilborn et al. 2003, Bryant 2009). Although many habitats in southeast
Alaska have been damaged by timber harvest or other management, Bryant (2009) states that there are
still numerous unaltered watersheds that can buffer the effects of climate change. Timely restoration work
in the altered areas can help to save stocks that are in danger.
This is not to say that there will not be adverse effects while the populations are adjusting to the new
conditions and stresses. In regard to salmon, Bryant (2009) stresses the potential need for cooperation
among all users groups to manage conservatively and reduce harvests, even if population stresses are not
readily apparent. Since we cannot determine the genetic composition of fish in every stream and habitat
niche, the management strategy should be to ensure that all existing stocks, based on locations and run
timing, have sufficient returns.
Current Research, Monitoring
As discussed in the previous section, much of the uncertainty about risk is due to a lack of understanding
about the biological processes and how species will respond. In addition, some basic parameters, such as
groundwater flows and temperatures, have not been studied. Researchers from the Pacific Northwest
Research Station and various universities are attempting to fill these knowledge gaps with a number of
studies on the Copper River Delta area, including some monitoring sites in the Eyak Lake watershed.
One study examines the life-history diversity of populations of coho and sockeye salmon in streams with
different seasonal thermal regimes. These differences may be related to location, groundwater input,
glacial melt, and surface water input. Using scales and otoliths from adult fish returning to spawn at these
sites, researchers will determine a number of life history parameters including size at emergence, number
of years spent in freshwater, and size at ocean entry.
If differences are correlated with varying temperature regimes, researchers may be able to predict what
might occur from the changes associated with climate change. For example, warmer winter air
temperatures may lead to increased amounts of surface water input in a system, as precipitation occurs as
rain rather than snow. The temperature change may then affect the incubating eggs and their rate of
maturation.
Another ongoing research project is a study of aquatic invertebrates in ponds with different temperature
regimes – some located in the relatively warmer west Copper River Delta and others in the colder east
delta. Again, location is used as a surrogate for the temperature changes that are predicted over time.
Differences in larval development, emergence timing, and possibly the annual number of generations of
some species, could have a significant effect on predators. This could be especially true for avian species
whose migratory patterns may be based on daily photoperiods rather than temperature.
There are a number of other research questions that should be asked for Alaskan areas, especially in
regard to the ability of species such as salmon to adapt to changed conditions. Also, in rural or remote
297 Assessing the Vulnerability of Watersheds to Climate Change