Level
established. Fish predation is an important regulator of benthic population
structure and dynamics (Wetzel 1983). Descriptive studies may prove useful for
understanding variability and developing a monitoring design. Hypothesis testing
and careful experimental design studies may be required to link benthic population
variables with their habitat.
Lake Fish Habitat
reservoir habitats for fisheries. Special habitat requirements for individual species
should be the focus. Due to the large surface area for most lakes, only a subset of
the most productive habitat should be monitored. One approach is to select a bay
or shoreline area that has important features for spawning and hiding and monitor
these areas during the critical times of the year. Substrate, weed beds, depth, cover,
and temperature are some candidate explanatory variables. Other habitat types to
consider are areas with a current, such as inlets and outlets, ledges, and channels.
Chemical and physical monitoring should relate to the fish population variable of
concern, specifically minimum DO, temperature, transparency, and
Heiskary
and Wilson (1988) list water quality and habitat features needed for lake trout,
smallmouth bass, largemouth bass, walleye, and northern pike. Monitoring
hypolimnetic DO during late summer and before turnover or under ice cover in
shallow bays is important for some species.
(1986) reviews morphoedaphic
indices and regression equations used by fisheries managers to estimate fish yield
or other variables for lakes and reservoirs. However, these relationships are
expected to provide information for first-cut estimates for fish population vari-
ables and not quantitative conclusions for use attainment or trend detection.
Fish population variability may be much greater than the change expected due to
impact alone. Particularly strong or weak year classes can mask the effects of land
treatment. Lake habitat monitoring can account for some population variability
not explained by differences in year class. Types of variables include hydrologic,
substrate, cover, water quality, and food required for a fish community.
Riparian and Shoreline Habitat Evaluations. Riparian ecosystems, which
Riparian and Shoreline Habitat
consist of the stream bank and flood plain, are a complex of the environment near
Evaluations
flowing water and the environment's organisms (Ewing, 1978). Lake and reser-
voir shorelines are also sometimes considered part of a riparian ecosystem.
Riparian environments have a great influence on aquatic life, and their restoration
may be less costly and can provide more immediate benefits to a fishery than
et al.
stream enhancements such as installing flow modification structures
1987). Riparian areas of perennial and ephemeral streams, estuaries, and other
water bodies may also function as pollutant buffers. Land use, shoreline and
overstory vegetation, and soil characteristics are common features of a riparian
habitat evaluation.
Methods for monitoring lake shoreline habitats are very similar to monitoring
methods for riparian evaluations. Effective riparian monitoring will consider
aquatic life requirements, the impacts of land use in the watershed, pollutant
sources, and buffering features of the riparian and shoreline environment. Level
I riparian monitoring variables and methods are given in Plafkin et al. (1989).
Physical and Chemical Variables
Monitoring the physical and chemical properties of water becomes more mean-
ingful when matched with the time and space scales of the problem. One of the
factors affecting water quality problems is the type of water resource (e.g., river,
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