2.3 Field Methods
71
Studies of temporal trends in surface water quality or characterization of
water quality conditions within a specific lake or stream or across a park or
forest can be designed to assess a variety of kinds of impacts and changes in
those impacts over time. For this to be successful, information is often needed
regarding basic watershed features that can have an impact on water quality.
These can include, for example, the variables listed in Table 2.8.
The ecological significance of aquatic ecosystem degradation and loss
caused by physical habitat alterations can, in some cases, exceed degradation caused by atmospheric deposition or human activities that affect water
chemistry. Therefore, physical habitat surveys of lakeshore areas, littoral
zones, stream channels, and riparian zones can be useful in conducting
overall habitat condition assessments and in interpreting water chemistry
data. Habitat information is helpful in the interpretation of what lake or
stream biological assemblages “should” be like in the absence of many types
of anthropogenic impacts. The physical evaluation can provide a reproducible, quantified estimate of habitat condition, serving as a benchmark
against which to compare future habitat changes that might result from
anthropogenic activities or extreme events. Furthermore, habitat information can aid in the diagnosis of probable causes of ecological impairment in
lakes or streams.
In addition to information collected in the field by the shoreline, stream
channel, or littoral zone surveys, the physical habitat description of each lake
or stream can include many map-derived or measured variables such as lake
surface area, shoreline length, stream width-to-depth ratio, and habitat integrity or complexity. Furthermore, an array of information, including watershed topography and land use, supplements the physical habitat information.
The shoreline, channel, and littoral surveys concentrate on information best
derived “on the ground.” As such, these survey results provide part of the linkage between large watershed-scale influences and those forces that directly
affect aquatic organisms day to day. Together with water chemistry, the habitat
measurements and observations describe the variety of physical and chemical
conditions that are necessary to support biological diversity and foster longterm ecosystem stability.
Habitat surveys should not be considered a necessary component of inventory
and monitoring. They require a commitment of time and resources. Nevertheless,
the data collected in such surveys can be helpful in the subsequent interpretation
of effects, especially if the documentation or quantification of effects relies on
collection of biological (i.e., phytoplankton, zooplankton, benthic invertebrates,
fish) as well as chemical variables.
The shoreline and littoral habitat surveys conducted by the EPA in the EMAP
program employed a randomized, systematic design with 10 equally spaced
observation stations located around the shore of each sample lake. Teams went
71
Studies of temporal trends in surface water quality or characterization of
water quality conditions within a specific lake or stream or across a park or
forest can be designed to assess a variety of kinds of impacts and changes in
those impacts over time. For this to be successful, information is often needed
regarding basic watershed features that can have an impact on water quality.
These can include, for example, the variables listed in Table 2.8.
The ecological significance of aquatic ecosystem degradation and loss
caused by physical habitat alterations can, in some cases, exceed degradation caused by atmospheric deposition or human activities that affect water
chemistry. Therefore, physical habitat surveys of lakeshore areas, littoral
zones, stream channels, and riparian zones can be useful in conducting
overall habitat condition assessments and in interpreting water chemistry
data. Habitat information is helpful in the interpretation of what lake or
stream biological assemblages “should” be like in the absence of many types
of anthropogenic impacts. The physical evaluation can provide a reproducible, quantified estimate of habitat condition, serving as a benchmark
against which to compare future habitat changes that might result from
anthropogenic activities or extreme events. Furthermore, habitat information can aid in the diagnosis of probable causes of ecological impairment in
lakes or streams.
In addition to information collected in the field by the shoreline, stream
channel, or littoral zone surveys, the physical habitat description of each lake
or stream can include many map-derived or measured variables such as lake
surface area, shoreline length, stream width-to-depth ratio, and habitat integrity or complexity. Furthermore, an array of information, including watershed topography and land use, supplements the physical habitat information.
The shoreline, channel, and littoral surveys concentrate on information best
derived “on the ground.” As such, these survey results provide part of the linkage between large watershed-scale influences and those forces that directly
affect aquatic organisms day to day. Together with water chemistry, the habitat
measurements and observations describe the variety of physical and chemical
conditions that are necessary to support biological diversity and foster longterm ecosystem stability.
Habitat surveys should not be considered a necessary component of inventory
and monitoring. They require a commitment of time and resources. Nevertheless,
the data collected in such surveys can be helpful in the subsequent interpretation
of effects, especially if the documentation or quantification of effects relies on
collection of biological (i.e., phytoplankton, zooplankton, benthic invertebrates,
fish) as well as chemical variables.
The shoreline and littoral habitat surveys conducted by the EPA in the EMAP
program employed a randomized, systematic design with 10 equally spaced
observation stations located around the shore of each sample lake. Teams went