Environmental Engineering Reference
In-Depth Information
4. Groundwater ecosystems are driven mostly by external inputs of
organic carbon. Little is known about energetic fluxes in most
groundwater ecosystems and nutrient budgets are not well
characterized for groundwaters.
5. Streams are essentially nonequilibrium ecosystems in which flooding
provides a strong abiotic influence on the ecosystem.
6. Nutrients spiral in streams as they cycle and are moved downstream.
7. The river continuum concept describes a series of physical and
biological changes that are expected when moving from small
headwater streams to large lowland streams.
8. Planktonic production and consumption can be very important in
deep lakes. Allochthonous inputs are minimal, but benthic
production can dominate in shallow lakes and reservoirs.
9. Wetland ecosystems are highly dependent on autochthonous
production. This production is deposited into wetlands as detritus
from emergent plants or produced by algae.
10. Aquatic habitats can be aligned on a continuum of abiotic axes that
describe many of the essential parameters that constrain ecosystem
function and biotic capacities.
QUESTIONS FOR THOUGHT
1. Why are wetland ecosystems generally more productive than streams?
2. Why do wetland ecosystems store a greater amount of carbon than
lakes or streams?
3. Can a lake ecosystem be described adequately with a
two-compartment model, one for the pelagic zone and another
for the limnetic zone?
4. Do whole communities evolve over time to optimally exploit
ecosystems?
5. If global warming increased the number of freshwater marshes by
converting northern peatlands into marshes, what would happen to
methane production?
6. How well does an equilibrium model represent stream ecosystems
relative to lake and groundwater ecosystems?
7. Should ecosystems be preserved in addition to endangered species?
8. Some people refer to “biotic integrity” and “ecosystem health” in the
context of conservation of the environment. What do you think these
terms mean and how should they be defined?
9. How can some ecosystems have a higher biomass of predators than
primary consumers?
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