Level II
Figure 3.4 Lake habitat zones.
7983)
PROFUNDAL
profundal zone and then to the sediments, where it settles and decomposes. As a
lake becomes more productive, the process is accelerated, and larger amounts of
organic matter are deposited, increasing the depth of the sediments. Decomposi-
tion of organic matter increases oxygen demand, which reduces hypolimnetic
oxygen concentration, sometimes below the levelcritical for fish and other aquatic
animals.
of hypolimnetic oxygen decreases benthic animal
richness and
numbers.
Interaction
Zones. Understanding the interaction between the three lake
zones is important for assessing impact. Wetzel (1983) has documented the
biogeochemical linkages between the littoral and pelagic zone. The organic and
sediment materials that fall from the pelagic zone into the profundal zone may
become recycled back to the pelagic zone during turnover.
Riparian and Shoreline Habitat Evaluations. Platts et al.
provide
comprehensive guidance on riparian habitat monitoring.
Riparian and Shoreline Habitat
Evaluations
Riparian Vegetation. Plants growing on a streambank and flood plain influence
streamside and
conditions. Riparian plants stabilize shoreline areas,
supply organic matter for organisms, reduce water velocity in'streams, provide
cover and food for fish, and intercept, control. and store solar radiation inputs to
the stream environment (Platts et al. 1987).
Several riparian vegetation variables may be used for evaluation based on a
numerical rating system. They include vegetative use by animals (such as grazing)
and the effects of cattle crossings, vegetative overhang, streambank stability, and
streamside cover. Detailed guidance on electronic forage analysis is also provided
by Platts et al. (1987) for determining forage vegetative production and use by
grazing animals in large areas.
Riparian Soils. Platts et al. (1987) define riverine geomorphic terms and the
processes that affect the distribution of sediments. They also describe soil
characteristics such as soil genesis, morphology, and taxonomy.
Measurements Above the Water Column. The vegetation of the shoreline and
the canopy affect shoreline stability, channel roughness, and running water
of-bank velocity.
vegetation and topography affect shading, light intensity,
and heating effects on the water column. Light and heat affect many water quality
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