THE GREAT LAKES

such as photosynthesis and transpiration within the canopy
(Sellers 1985, 1987) . The close connection of absorbed
photosynthetically active radiation (APAR: .4-.7 pm) to
chlorophyll density, which can be estimated remotely, leads
to near-linear relationships among canopy properties of
APAR, photosynthetic capacity P C , minimum 7
resistance (lr), and the two vegetation indices.
Theoretically, integrating multitemporal measurements of
reflected radiation in a given region should provide an
estimate of gross primary productivity (Tucker and Sellers
1986).
Likewise, satellite and aircraft sensors provide a way
to observe water body dynamics and biological productivity.
The greatest degree of light penetration into water occurs
in the visible wavelengths, also the'region of chlorophyll
absorption. Patterns of surface planktonic biomass and
chlorophyll fluorescence can be used to derive estimates of
primary productivity. Patterns of phytoplankton pigment
groups allow further delineation of the phytoplankton
community into some functional group classes (e.g., Carder
and Steward, 1985).
Pollutants (both inorganic sediments
and organic constituents) may affect the reflective or
emissive properties of water bodies. Relative turbidity is
easily detected as tonal changes in remotely sensed imagery
(e.g. , Klemans et al. 1973 ; Strong 1978) . Wavelength bands
in the thermal infrared estimate the surface temperature
(upper few microns) of water bodies, from which plume and
circulation patterns can be depicted (e.g., Schott and
Schimminger 1981). Numerous ocean studies have shown that
at microwave frequencies, where water is opaque to
radiation, surf ace structural features such as currents and
eddies are measurable (e.g. , Kasischke et al. 1984 ; Vesecky
and Steward 1982) .
The task of landscape ecology, as defined by Toth
(1988), is to:
1) discover, by way of analysis, which factors are
operationally significant;
2) determine how these factors bring about change in the
landscape; and
3) describe how these factors define the spatial (form)
characteristics of a landscape.
In light of these objectives and the foregoing discussion,
the synoptic view of the land and seascape as provided by
remote sensing instrumentation is essential to the analysis
of large-scale ecological pattern and process. The
critical issue is how best to interpret the emergent