Environmental Engineering Reference
In-Depth Information
Sunlight
Painted
turtle
Green
frog
Blue-winged
teal
Muskrat
Pond
snail
Littoral zone
Limnetic zone
Diving
beetle
Plankton
Profundal zone
Benthic zone
Northern
pike
Yellow
perch
Bloodworms
Active Figure 5-35
Natural capital:
distinct zones of life in a fairly deep temperate zone lake.
See an anima-
tion based on this figure and take a short quiz on the concept.
earth's surface as rain or snow that melts during warm
seasons. The downward flow of surface water and
groundwater from mountain highlands to the sea typi-
cally takes place in three aquatic life zones character-
ized by different environmental conditions: the
source
zone,
the
transition zone,
and the
floodplain zone
(Fig-
ure 5-36).
As streams flow downhill, they shape the land
through which they pass. Over millions of years the
friction of moving water may level mountains and cut
deep canyons, and the rock and soil removed by the
water are deposited as sediment in low-lying areas.
Streams receive many of their nutrients from bor-
dering land ecosystems. Such nutrient inputs come
from falling leaves, animal feces, insects, and other
forms of biomass washed into streams during heavy
rainstorms or by melting snow. To protect a stream or
river system from excessive inputs of nutrients and
pollutants, we must protect its watershed.
Freshwater Inland Wetlands: Vital Sponges
Inland wetlands absorb and store excess water from
storms and provide a variety of wildlife habitats.
Inland wetlands
are lands covered with fresh water all
or part of the time (excluding lakes, reservoirs, and
streams) that are located away from coastal areas. They
include
marshes
(dominated by grasses and reeds with
few trees),
swamps
(dominated by trees and shrubs),
and
prairie potholes
(depressions carved out by glaciers).
Other examples are
floodplains
(which receive excess
water during heavy rains and floods) and the wet
arctic
tundra
in summer. Some wetlands are huge; others are
small.
Some wetlands are covered with water year-
round. In contrast,
seasonal wetlands
remain underwa-
ter or soggy for only a short time each year. They in-
clude prairie potholes, floodplain wetlands, and bot-
tomland hardwood swamps. Some stay dry for years
