||How are Lake Habitats
Several activities can disrupt lake habitats by reducing
the amount of sunlight or oxygen in the water.
Erosion of the lake shore will deposit mud, sand or rubble
on the lake bottom. Silt, in the form of muddy runoff, clouds
the water and limits the amount of sunlight reaching the
plants and algae. Without sufficient sunlight, photosynthesis
is reduced, resulting in impaired growth.
- infos - about-us - products - news - productsreviews - informations - contact - contacts - aboutus
Septic fields and sewage from cottages, homes and commercial
buildings can disrupt the ecologic balance of a lake.
Decomposition of plants and algae consumes oxygen. If more
oxygen is consumed than is produced, organisms, including
fish, may not survive. Sensitive species such as trout may
die off completely if oxygen is depleted for even a short
period of time. Low levels can be critical in summer or
winter, when little oxygen enters the water through the
ice and plants that are still growing are not producing
Land development can increase siltation, cause chemical
runoff or leach freshly exposed soils. Land clearing can
remove the protective surface cover of plants and increase
the flow of water and eroded materials into the lake. Surface
and groundwater may also be more exposed to the sun and
become warmer, disrupting productivity in small lakes.
Homes, cottages and commercial buildings can disrupt the
ecological balance of a lake through the release of sewage
from septic fields or through runoff from fertilized lawns
Wave-deflecting structures, such as rock piers, dikes or
cribs, can change wave and current patterns. When poorly
placed, they may divert wave or current energy to other
parts of the lake and erode the shoreline. Wave deflecting
structures can change wave patterns and cause shoreline
Agricultural activity can release high levels of fertilizers
and pesticides into a lake. Runoff from manure piles and
silage pits may also make its way into a lake. Herbicides
commonly used in farming operations can suppress production
and growth of many aquatic plants and organisms. High levels
of nitrogen and phosphorus, found in fertilizers, can cause
massive blooms of plankton and aquatic plants. As these
organisms die and decompose, they use oxygen in the water,
reducing the oxygen available for fish and plants.
Industrial activity upstream from or on a lake may discharge
toxic chemicals that can harm or kill plants and animals
outright. Certain chemicals like heavy metals, and organic
compounds such as PCBs, may concentrate in plant and animal
tissues (bio-accumulation). High levels of some of these
compounds could be hazardous to humans. Toxic chemicals
from industrial activity can harm fish and plants in a lake.
Introduction of Non-native Species to a Lake
Introducing non-native (nonindigenous) fish or plants can
seriously reduce populations of native species. If a newly
introduced species is not controlled naturally through predation
and competition, its increasing population may reduce the
number of fish native to the lake. Experience shows that
mixing species from different areas can also spread disease.
Canal construction or the diversion of water can cause non-native
species to enter a watershed.