A |
| Acid deposition |
Acids (e.g., nitric and sulfuric) form as the result
of burning fossil fuels and also emanate from various
industrial sources (e.g., paper mills, steel mills).
When volatilized into the air, they accumulate on dust
particles in the atmosphere and eventually settle to
the ground, often being brought down by rain. Buffering
compounds in the ground neutralize acid-laden rainwater.
Unfortunately, many soils in the industrialized regions
of the world have been depleted of its buffering capacity.
When the soil can no longer negate the acids deposited,
leaching of heavy metals occurs (e.g., calcium, magnesium,
molybdenum). Aluminum is the last metal to leach out,
often creating toxic events in trout streams during
the spring when acid snow melts. In northern and central
Sweden and Norway, thousands of lakes have been sterilized
because they lack an outlet, and the land around those
bodies of water no longer has the capacity to neutrali-ze.
The same process has evolved in a number of Adirondack
lakes in northern New York State.
Learn More
|
| |
| Algal Bloom |
An increased growth of algae (single-cell plants) in
response to an increase in nutrients (e.g., phosphates
and nitrates, phosphate detergents, or fertilizers).
Learn More
|
| |
| Allochthanous |
Any external source of energy for the
stream (e.g., dead leaves, branches, and dead trees that
fall into the river). Most freestone rivers get about
60% of their energy in this fashion.
Learn More
|
| |
| Anandromous fishes |
Any species of fish that lives as an
adult in salt water and spawns in freshwater. For example,
all species of salmonids, striped bass, and shad.
Learn More
|
| |
| Anchor Ice |
Ice that forms on the bottom of the river.
It can cause great damage by trapping immature macro invertebrates
to the underside of rocks and killing them, thus lowering
the energy flow into the secondary consumer group (e.g.,
trout, suckers, dace and other insect-eating predators).
Learn More
|
| |
| Arbor Day |
A day set aside for tree planting. Each
state has a specific time in the year for this purpose
designated by the National Arbor Day Foundation. These
dates are carefully chosen to correspond to the time of
year most favorable for the survival of newly planted
trees and shrubs. Arbor Day is always on a Friday to allow
K-12 schools across the country the opportunity to participate
in this useful activity.
Learn More
|
| |
Artesian aquifer |
Artesian aquifers are associated with
mountainous regions of the world. The water in this configuration
(see also: Confined Aquifer) is trapped in a porous rock
layer lying between two impermeable layers of rock (i.e.,
confined aquifer). It is under great pressure due to the
steep gradient. Whenever the confined aquifer exits to
the surface at ground level, a spring occurs.
Learn More
|
| |
| Assemblage |
A collection of plants or animals of
the same taxa (e.g., order, family, genus) living within
a common geographic locale, often in competition with
one another for food, space, energy, etc.
|
| |
| Autochthonous |
Sources of energy that come from within
the river, itself. All spring and limestone streams and
many tailwater rivers account for more than half of their
annual energy budget from the macrophytes that grow in
situ. Algal growth on the rock substrate in freestone
rivers and streams represents another important internal
energy source.
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|
| |
| Aquifer |
Geological strata consisting of porous
rock allowing water to accumulate within it. It can be
either confined or unconfined (see definitions for both).
Learn More
|
| |
B |
| Bacteria |
Single cell organisms that possess cell
walls and lack a definable nucleus for their DNA (i.e.,
prokaryotes). Bacteria are critical for the functioning
of all ecosystems and are thus essential for the in-stream
conversion of dead plant material into a form that macro
invertebrates find appetizing.
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|
| |
| Basaltic Rock |
Geological formations that began as volcanic lava flows.
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|
| |
| Benthic Zone |
The bed of the river, stream or creek. Benthos is Greek
for “bottom”.
Learn More
|
| |
| Biomass |
The total amount of living material
expressed as either grams of carbon or kilocalories (1,000
calories) for a given area of space (e.g., per square
meter). Kilocalories are calculated by placing together
all of the living matter collected for a defined area
of riverbed and drying it. After recording the total weight,
it is then placed it in a bomb calorimeter. The calorimeter
is filled with pure oxygen and a spark ignites the contents.
The amount of heat given off is recorded in calories per
gram of dried material.
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|
| |
| Bio-productivity |
The total amount of living material (number
of organisms or kilocalories/mile) a given area of river
can produce (see: Biomass) within a prescribed period
of time (usually one calendar year). Often, this measurement
is in terms of a specific type of aquatic life form (e.g.,
macrophyte, macro invertebrate, fish).
Learn More
|
| |
| Boreal Forest |
Circumpolar northern pine forests.
Learn More
|
| |
C |
| Caddis fly |
Insects in the Order Trichoptera. The
order name means “hair wing” in Latin. There
are 15 sub-orders with over 5,000 species, and 1,200 living
in various aquatic habitats throughout North America.
They are particularly abundant in most trout streams throughout
the world. Caddis flies are some of the most important
members of the macro invertebrate community that make
up the food webs of most rivers and streams. They undergo
complete metamorphosis (egg - larva - pupa - adult fly).
Most are filter-feeders, while some are entomophagus (i.e.,
they eat other insects).
Learn More
|
| |
| Calcium carbonate |
This is the main component of limestone.
Calcium is an essential ingredient of the macro invertebrate
exoskeleton. This compound dissolves in weak acid, dissociating
into Ca++ and (-)CO3. In doing so,
it makes calcium available to the life forms of the stream,
and at the same time changes the overall pH of the environment
to slightly basic in pH (typically 7.2-7.8). These are
the two reasons why limestone streams are so productive.
Learn More
|
| |
| Calorie |
A unit of heat energy. The amount of
heat needed to increase the temperature of 1 gram of water
by one degree centigrade. Ecologists tend to express their
data as kilocalories (i.e., 1,000 calories).
Learn More
|
| |
| Catandromous fishes |
Any species of fish that lives in freshwater
and spawns in salt water. For example, the American eel
lives as adult fish in rivers along the east coast of
the United States, and spawns in the Sargasso Sea off
the coast of Florida.
Learn More
|
| |
| Channelization |
The straightening of a river by removing
meanders, ostensibly for the purpose of flood control.
Usually, bulldozers and other heavy equipment are used.
Channelization destroys the benthos and hyporheic zones,
as well as the riparian ecotone. Disconnecting the communities
of life forms of the river by short-circuiting the flow
of energy through each trophic level is the end result.
Recovery is protracted, depending upon the extent to which
the banks were altered. The Kissimee River in Florida,
for example, remained straightened for many years after
extensive channelization by the Corp of Army Engineers.
Today, that river is scheduled to be routed back to its
original riverbed, because studies have shown that the
altered river had too great an effect on natural processes
in the everglades. Many other smaller rivers throughout
the world suffer from channelization each year.
Learn More
|
| |
| Community |
Different taxa of plants and animals
living cooperatively in a common geographic region, through
which energy flows, thus linking them to a common ecosystem
(see: Assemblage).
Learn More
|
| |
| Competition |
The vying for common resources (energy,
space, etc.) in a given environment among individual organisms.
This activity is one of the major biological forces regulating
the structure and composition of macro invertebrate communities
on the benthos of most rivers.
Learn More
|
| |
| Confined Aquifer |
Water that is trapped in a layer of permeable
rock lying between two layers of impermeable rock is referred
to as a confined aquifer. It is under great hydrological
pressure and often results in an artesian spring (see
Artesian Aquifer).
Learn More
|
| |
| Crustacean |
Any organism in the Phylum Arthropoda,
Class Crustacea. This diverse group includes crabs, lobsters,
crawfish, and amphipods (scuds). The latter two groups
are often found in limestone streams in high abundance
and contribute significantly to the food chains and food
webs of that river type.
Learn More
|
| |
| Current |
Movement of water down a gradient of
gravity. Current is measured in feet per minute. The scientific
notation Q=AV is a mathematical expression of current,
where Q is the current, and A is the cross sectional area
of the river at any given point along its course times
the velocity - V (feet/min) - of the water flowing passed
a fixed point on the bank.
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|
| |
D |
| Defoliation |
The act of removing plant life from a
given region. Elimination of plants from along the riparian
ecotone of freestone rivers significantly detracts from
the bio-productivity of those aquatic ecosystems.
Learn More
|
| |
| Delta |
An alluvial deposit of silt from a large river system
at the level of the estuary.
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|
| |
| Detritus |
Dead plant and animal material. Detritus
is reduced to small particles by microbial decay and shredder
macro invertebrates in most rivers. Re-cycling of detritus
constitutes the base of the energy flow pyramid from plants
to top carnivores in most freshwater aquatic and terrestrial
ecosystems.
Learn More
|
| |
| Developmental Cycle |
The complex biological process through
which all living organisms go in order to complete their
life cycle. Macro invertebrates complete their transformation
from egg to adult employing two separate strategies; namely
incomplete (egg - nymph - adult = mayflies and stone flies)
or complete metamorphosis (egg - larva - pupa - adult
= caddis flies and all diptera).
Learn More
|
| |
| Diptera |
Insects with two wings (di=two, aptera=
wing). Included in the diptera are mosquitoes, house flies,
deer flies and black flies. Midges, mosquitos, black flies
and deer flies are aquatic insects that are found in abundance
in some freestone rivers.
Learn More
|
| |
| Dissolved Oxygen |
Gaseous oxygen comprises 20% of the total
gas in the atmosphere at sea level. It is very soluble
in water and the amount that can dissolve in it depends
upon two physical parameters: pressure and temperature.
By far, temperature is the most important one regarding
rivers, since the atmospheric pressure at sea level is
about the same for the water in a river as the land around
it. Trout and macro invertebrates require an ideal concentration
of 6-10 milligrams of dissolved oxygen per 1,000 milliliters
of water. At higher altitudes, reduced atmospheric pressure
becomes important, especially for alpine situations where
the amount of oxygen in the atmosphere is reduced and
the pressure is also lower. However, the colder temperatures
compensate for these changes, for the most part.
Learn More
|
| |
| Drawdown |
The use of water from an impoundment
controlled by a valve or lock system operated from the
top, middle, or bottom portion of the dam.
Learn More
|
| |
| Drift |
A macro invertebrate behavior pattern
keyed to the day/night cycle (i.e., diurnal rhythm). Many
species of arthropods participate in drift each night
during the summer months. Typically, organisms rise up
into the water column at two distinct times during the
night; the first at about 1 hour after dark and the second
at 4-6 am. They drift downstream until they reach the
bottom of the pool in which they reside. As morning approaches,
they migrate long the bottom of the river back to their
original place of lift off. The purpose of drift is still
being investigated.
Learn More
|
| |
E |
| Ecology |
Derived from the Greek word “Oikos”,
it translates as ”Living together in the same house”.
Today, we understand the word ecology to stand for the
science of how disparate groups of organisms cooperate
and compete in a common geographic region to create interdependencies
that we call ecosystems. This brief working definition
falls far short of describing the breadth and depth of
ecological sciences.
Learn More
|
| |
| Ecological modeling |
The quantitative science in which computer-assisted
mathematics and related software programs are employed
to attempt to describe complex processes of nature (atmospheric
modeling, predator-prey relationships, climate change
models, etc.). Most ecological models take into account
extensive physical, chemical, and biological data and
apply them to a variety of levels of interactions.
Learn More
|
| |
| Ecosystem |
Most ecologists will not commit to defining
what constitutes an ecosystem. Here is meant any community
of a wide variety of plants and animals bonded together
by a common geographic region and sharing the flow of
energy that drives the system to equilibrium. Ecosystems
are complex enough to allow the development and maintenance
of stable food chains and food webs. This activity links
all those life forms into interdependencies. Most of the
energy cycles through the communities located within the
confines of a given ecosystem unless that system becomes
disturbed (e.g., encroachment, natural disasters, etc.).
Learn More
|
| |
| Ecosystem Management |
The daunting task of insuring that ecosystem
services are functional in regions impacted by the presence
of human activities. This newly coined phrase is still
undergoing field testing. We have yet to “get it
right”, but continue to try. To manage an ecosystem,
we must first understand how it works, and that is the
crux of the problem.
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|
| |
| Ecotone |
The edge of two or more ecosystems. For
example, the two banks of the river, the interface between
the woods and an open field, a hedgerow next to a field
of tall grass, the meeting of freshwater with salt water
(i.e., estuary), etc. This zone is a region of high biodiversity
and attracts plants and animals to it that cannot usually
be found in any of the bordering ecosystems. For this
reason, alone the ecotone is a valued (albeit small) piece
of real estate.
Learn More
|
| |
| Eddy |
A slowing down of or reversal of current
in a river, usually caused by the obstruction of the main
flow by a large object such as a rock, fallen tree or
sand bar. Eddies are resting places for fish and large
amounts of detritus collect there at certain times of
the year.
Learn More
|
| |
| Energy Flow |
The transfer of energy (i.e., calories)
from one group of organisms to another by the ingestion
of biologically produced material. There are typically
four trophic levels through which energy passes in any
given ecosystem: 1. Primary producers (plants) fix energy
from the sun into new plant tissue; 2. Primary consumers
eat plants; 3. Secondary consumers eat herbivores; and
4. Tertiary consumers (i.e., top carnivores) eat secondary
consumers. 5. Animals at every trophic level die periodically
and the nutrients they represent are re-cycled by detritivores
(i.e., shredder macro invertebrates and microbes like
bacteria and fungi), or are consumed by scavengers. In-ground
nutrients are used by the primary producers. Its a tightly
connected cycle when it functions unhampered by outside
influences. Parasitism and intra- and inter-specific competition
contribute to reducing the efficiency of the energy transfer
system.
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|
| |
| Encroachment |
Disturbing natural systems by activities
such as construction of housing, shopping malls, clear-cut
harvesting of forest products, farming, dam building,
etc.
Learn More
|
| |
| Essential Nutrient |
An element or compound required for the
life of a given organism. For example, humans need a minimum
of 11 kinds of amino acids and two kinds of fatty acids,
as well as numerous other nutrients for normal growth
and development. Macro invertebrates need calcium, nitrates
and phosphorous, as well as numerous other essential nutrients.
Learn More
|
| |
| Estuary |
An aquatic ecotone between the river and the ocean.
There are some 3,000 linear miles of estuary shoreline
in the world. It is a highly productive place, and serves
as the nursery for countless species of fish and invertebrates.
It is also one of the most encroached upon areas, as well.
Learn More
|
| |
| Eutrophic |
Environments enriched in essential nutrients.
Many southern United States lakes are classified as eutrophic
and contain large populations of macrophytes. They are
enriched in animal species compared to oligotrophic lakes
(see: Oligotrophic).
Learn More
|
| |
| Evolution |
Biological change over geologic time through the process
of random mutation and natural selection.
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|
| |
| Exoskeleton |
The outer, hard exterior of all arthropods (i.e., insects,
arachnids, crustacea, etc.).
Learn More
|
| |
F |
| Feeder Stream |
Tributary of the main stem of a river. It is an important
refugia for stream life during times of environmental
stresses (e.g., thermal events, droughts, etc.).
Learn More
|
| |
| Fertilizer |
Supplemental source of nutrients. There
are two kinds of fertilizers: 1. Synthetic mixtures of
chemicals enriched in elements and compounds not found
in abundance in natural systems. These manufactured products
unavoidably contain trace elements that can accumulate
to higher concentrations if the product is used frequently.
Such is the case in the Imperial Valley of California
where selenium, a trace element, is now found in the water
table in some places at toxic levels for waterfowl. 2.
Natural fertilizers include manures from various animal
sources and composted non-edible portions of plants.
Learn More
|
| |
| Filter Feeder |
An organism that obtains all of its food
in the form of fine particulate organic matter (FPOM).
Many species of macro invertebrates in the river are filter
feeders. Many possess specialized organs for doing so.
For example, brush-like hairs around the mouth and forelegs
facilitate this kind of feeding behavior in Isonychia
bicolor, a species of mayfly. Other species of Ephemeroptera
employ intricate nest building in the sandy deposits behind
rocks, while most Trichoptera (caddis flies) build silk
webs to trap FPOM. Clams, oysters, and a wide variety
of coral reef organisms also feed in this fashion.
Learn More
|
| |
| Food Chain |
A linear expression of the flow of energy,
in which a low number of different taxa of organisms are
involved in its transfer from one trophic level to the
next. For example, sunlight, grass, cow, or: sunlight,
algae, minnows, trout (lake food chain).
Learn More
|
| |
| Food Web |
An expression of the flow of energy through
various communities of organisms in ecosystems, typically
consisting of four or more trophic levels. Food webs dissipate
energy, spreading it out laterally to communities of organisms
living at the same trophic level. Most stream and river
ecosystems are comprised of food webs, not food chains.
For example, sunlight, in-stream macrophytes, macro invertebrates,
trout and other insect-eating fishes, predators of trout.
Many macro invertebrate and fish species feed on in-stream
insects, thus taking away from the flow of energy towards
the top trophic levels.
Learn More
|
| |
| Fragmented Ecosystem |
An ecosystem that has been encroached
upon in such a way as to create two or more smaller regions,
as is the case when logging roads are made through portions
of forest, canals are dug separating land regions, or
major highways are constructed, severing a wildlife refuge
into two parts. Fragmentation is occurring at a rapid
rate, as humans seek to expand their living spaces to
include wild areas near rivers, streams and creeks. Maintaining
green belts along riparian ways is an enlightened developmental
approach to help repair some of the more deleterious effects
of fragmentation.
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|
| |
| Freestone River |
A river type commonly occurring in mountainous
areas whose sources of water include snowmelt and a series
of coalescing springs and tributaries. The benthic zone
is strewn with smooth rocks, boulders, gravel and sand.
Few species of macrophytes can live there due to the steep
gradients and swift currents. Macro invertebrate communities
typically form food webs, and productivity is modest compared
to limestone streams, due to the slightly acidic pH of
the water.
Learn More
|
| |
| Fungus |
Any organism in the Kingdom Mychota.
These organisms are incapable of photosynthesis, so they
derive all their food from either dead or living plants
and animals (i.e., they are saprophytes). Some fungal
species are parasitic. Most are essential detritivores
for the freestone rivers, and in terrestrial ecosystems,
the rain forests. Many aquatic fungi or water molds (hyphomycetes)
participate in the breakdown of leaf and other plant materials.
They are essential, along with bacteria, for making the
decaying vegetation palatable for the macro invertebrate
shredder species.
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|
| |
G |
| Genus |
A level of taxonomic classification that immediately
precedes species.
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|
| |
| Gradient |
An expression of the variability of physical,
chemical, and biological properties of a given ecosystem.
A gradient of current speed is created in the river as
it cascades down the mountain side. In this instance,
daily fluctuations in water temperature, the amount of
dissolved oxygen, pH, suspended particulates, macro invertebrate
communities, fish species, and other characteristics of
the freestone river are distributed along the gradient
of gravity, insuring that no two stretches of the river
behave the same.
Learn More
|
| |
| Granite |
An ancient (billions of years old), very
hard, crystalline rock formation whose origins were solidified
portions of molten crust of the earth. Most of Yosemite
Park is granite.
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|
| |
| Groundwater |
Water contained within porous rock below
the surface, in either a confined or unconfined aquifer.
Most limestone rivers begin as underground springs, while
most freestone rivers do not.
Learn More
|
| |
H |
| Habitat |
Referring to the physical locale of a plant or animal.
Not to be confused with niche.
Learn More
|
| |
| Hardwood Forest |
Any forest in which the dominant species
of trees are deciduous, such as oak, maple, beech, ash,
etc. These forests are essential for the flow of energy
into most of the world’s freestone rivers.
Learn More
|
| |
| Heavy Metal |
Rock music aside, heavy metals include
tin, lead, gold, platinum, selenium, mercury, cadmium,
vanadium, iron, nickel, silver, and cobalt. Many of these
are toxic in greater than trace amounts, but toxicity
(usually expressed as the amount of a given substance
needed to kill 50% of a population of organism, or LD50)
varies with the tolerance limits for each organism. Many
of these elements are contaminants of freestone rivers
and emanate from abandoned mining operations. Other metals
can also present problems for trout. For example, aluminum,
a naturally occurring element found in trace amounts in
most soils, is extremely toxic in low levels (100 parts
per billion), especially when calcium is in short supply.
Aluminum becomes a problem in rivers receiving acid water,
as occurs in the spring throughout the North Eastern United
States in the form of acid snow melt.
Learn More
|
| |
| Herbicide |
Agrochemicals used to eliminate non-economic
species of plants. Most are group-specific in that regard,
but some are generally toxic for most plants and for many
animal species, as well. Indiscriminant use of herbicides
in agricultural settings has resulted in toxic situations
for neighboring rivers during times of high runoff, as
might occur after a heavy rain storm, or in the Spring
when snow melt runoff is common.
Learn More
|
| |
| Herbivore |
Any animal that predominantly eats plants.
Almost all animals will take a bite of meat now and then,
so there are few strict herbivores in nature.
Learn More
|
| |
| Hydrological Cycle |
Water falls to earth as rain and becomes
included into the groundwater (see Aquifer), or runs into
standing bodies of water, where it remains for some time
thereafter. Eventually most of the surface water returns
to the oceans via rivers, where it evaporates and condenses
forming clouds. Cycles of cloud formation, rain and terrestrial
runoff characterize the hydrological cycle. Groundwater,
on the other hand, can take centuries to exit from the
aquifer and return to the oceans. The same is true for
water that is trapped as snow in the polar regions. Only
about 2% of all the drinkable water on earth is in liquid
form, and 20% of that is contained in just one place,
Lake Baikal, Russia.
Learn More
|
| |
| Hyphomycetes |
Water molds (see: Fungi) important to
the cycling of energy through aquatic ecosystems. The
breakdown of leaf material in the freestone river is highly
dependent on this group of fungi. There is a succession
of species of hyphomycetes during the decaying process,
which may take the better part of a year. The progression
of fungal species onto the surface of a given leaf is
specific to the species of leaf being colonized, and probably
specific to the place along the gradient of the river,
as well.
Learn More
|
| |
| Hyporheic Zone |
That region of a river which typically
starts at the benthic zone and goes downward until groundwater
from the river is no longer included in the substrate.
This is a relatively new area for ecological study. It
is strongly suspected that this poorly oxygenated zone
serves as a reservoir for stream life, particularly macro
invertebrates, at times of drought, flood, and other environmental
stress. Channelization destroys this zone, along with
the benthic zone, as well.
Learn More
|
| |
I |
| Impoundment |
Any standing body of water created by a damming a river.
Learn More
|
| |
| In situ |
A Latin word denoting within. For example, macrophytes
grow in situ in limestone streams.
Learn More
|
| |
K |
| Keystone Species |
A plant or animal the removal of which
causes a significant rearrangement of energy flow relationships
to occur within that ecosystem. In a classic experiment
conducted by Dr. Mary Powers at The University of California
at Berkeley (see: http://ib.berkeley.edu/labs/power/index.shtml),
excluding the top carnivore, the steelhead trout (Onchorynchus
mykiss), from a portion of freestone river by placing
wire baskets over portions of the benthos resulted in
a collapse of the balance between herbivorous macro invertebrates,
insectivorous fishes, such as the stickleback, and the
top carnivores. Sticklebacks are favorite food items for
steelhead and eliminating the possibility for predation
resulted in the sticklebacks consuming all herbivorous
insects within the confines of the basket. As the result,
an overgrowth of filamentous algae occurred within the
area of the basket. In this instance, the steelhead trout
was the keystone species. Therefore, over harvesting predator
species in riverain ecosystems results in energy flow
rearrangements the outcome of which does not usually favor
maintaining that environment as trout habitat. In limestone
streams, the scud (crustacean amphipod) is a keystone
species.
Learn More
|
| |
L |
| Leaching |
The chemical process by which elements
(e.g., sodium, calcium, aluminum, etc.) are selectively
dissolved out of the solid substrate of the riverbed or
stream bank. Leaching occurs under slightly acid conditions.
When organic matter falls into the river, especially leaves,
leaching also occurs, allowing soluble substances such
as sugars, plant pigments and other organic compounds
contained within the leaf to dissolve into the water.
The input of these plant-derived materials in the fall
triggers the growth of aquatic microbes that help prepare
the leaf surface for the shredder species of macro invertebrates.
In regions where acid deposition and precipitation is
the rule (i.e., Northeastern United States), seasonal
leaching of heavy metals, primarily aluminum, into the
river causes the death of countless fish and macro invertebrates.
Acid environments also inhibits the growth of aquatic
microbes. Coal and gold mining operations have left acidic
and arsenic compounds in the slag heaps that occasional
leach into rivers and despoil them for long periods of
time.
Learn More
|
| |
| Limestone Stream |
A slow moving body of water characterized
by a shallow gradient, a slightly basic pH, smooth currents,
in situ macrophytes, cold water, and a high rate of bio-productivity.
In Europe, they are called chalk streams.
Learn More
|
| |
M |
| Macro Invertebrate |
Any arthropod (e.g., Order Diptera, Coleoptrea,
Trichoptera, Ephemeroptera, Plecoptera) or Gastropod (snail)
species living within the confines of the river. These
communities of animals form complex food webs, and typically
occupy the second and third trophic levels for most of
the world’s cold running water ecosystems.
Learn More
|
| |
| Macrophyte |
Any species of large vascular plant living
within the river. Mostly found in limestone and spring
creeks, and large warm water rivers.
Learn More
|
| |
| Main stem |
The final section of river, below which
cannot be found any tributaries larger in volume than
itself.
Learn More
|
| |
| Mayfly |
All species of macro invertebrates in
the Order Ephemeroptera. There are 2,000(+) species worldwide,
and 620(+) species in North America and Mexico.
Learn More
|
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| Meander |
The winding of a river back and forth
within its banks. Erosional activity of moving water creates
meanders and the precise number of switch backs from left
to right looking downstream depends upon the width of
the river, the speed of the current and the substrate
over which the river flows (see: Luna Leopold’s
A View of the River for an excellent analysis of the physics
of meanderings). In very large rivers, ox bow lakes are
a common feature of the landscape due to severe meandering
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