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Glossary of Terms

[A] [B] [C] [D] [E] [F] [G] [H] [I] [K] [L] [M] [N] [O] [P] [R] [S] [T] [U] [W]

 

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
  http://www.dnr.state.md.us/streams/acid/
http://www.hubbardbrook.org/education/Introduction/Intro13.htm

 
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
  http://www2.ncsu.edu/ncsu/wrri/reports/report188.html

 
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
  Link 1
 
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
  http://www.lsc.usgs.gov/CAFLindex.asp

 
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
  Link 1

 
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
  http://www.arborday.org/

 

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
  http://www.bartleby.com/61/imagepages/A4artwel.html
 
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.

Learn More
  Link 1
Link 2
 
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
  http://octopus.gma.org/katahdin/aquifer.html

 

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.

Learn More
  http://www.ucmp.berkeley.edu/bacteria/bacteria.html

 
Basaltic Rock

Geological formations that began as volcanic lava flows.

Learn More
  http://www.fcs-net.com/biddled/earth_structure.htm

 
Benthic Zone

The bed of the river, stream or creek. Benthos is Greek for “bottom”.

Learn More
  http://www.benthos.org/

 
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.

Learn More
  Link 1
 
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
  http://www.umt.edu/biology/flbs/Research/SalmonRiversEcology.htm

 
Boreal Forest

Circumpolar northern pine forests.

Learn More
  http://www.britannica.com/eb/article?eu=127609

 

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
  http://sites.state.pa.us/PA_Exec/Fish_Boat/sepoct99/cadisfly.htm

 
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
  http://www.digital-analysis.com/Limestone.htm

 
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
  Link 1
 
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
  http://www.aquarium.org/education/spotlight/anadromdy/catadromy.htm

 
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
  http://www.amrivers.org/fishwildlife/fwthreats.htm
 
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
  http://www.ossm.edu/biology/communit.htm

 
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
  http://regentsprep.org/Regents/biology/units/organization/population.cfm

 
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
  Link 1

 
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
  http://www.vims.edu/tcs/

 
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.

Learn More
  Link 1

 

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
  http://www.umass.edu/tei/mwwp/riverecology.html#logging

 
Delta

An alluvial deposit of silt from a large river system at the level of the estuary.

Learn More
  http://www.earth.ox.ac.uk/~tony/watts/new_pages/watts8.html

 
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
  http://collections.ic.gc.ca/abnature/Ecosystems/detritus.htm

 
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
  http://www.epa.gov/bioindicators/html/lifecycle.html

 
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
  http://www.sel.barc.usda.gov/diptera/diptera.htm

 
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
  http://bcn.boulder.co.us/basin/data/COBWQ/info/DO.html

 
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
  http://www.delawareriverfoundation.org/about_us.html

 
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
      Link 1

 

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
  http://www.esa.org/

 
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
  Link 1

 
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
  http://www.ecostudies.org/

 
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.

Learn More
  http://esa.sdsc.edu/ecmtext.htm

 
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
  http://www.western.edu/faculty/jsowell/ecotones.html

 
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
  Link 1

 
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.

Learn More
  http://www.fes.uwaterloo.ca/crs/ers305/2.html

 
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
  http://www.tu.org/
http://www.onda.org/library/archives/cleanref.html

 
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
  Link 1

 
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
  http://inlet.geol.sc.edu/estecohp.html

 
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
  http://www.epa.gov/maia/html/eutroph.html

 
Evolution

Biological change over geologic time through the process of random mutation and natural selection.

Learn More
  http://www.pbs.org/wgbh/evolution/

 
Exoskeleton

The outer, hard exterior of all arthropods (i.e., insects, arachnids, crustacea, etc.).

Learn More
  http://www.cals.ncsu.edu:8050/course/ent425/tutorial/integ.html

 

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
  http://www.hubbardbrook.org/research/data/stream/stream.htm
http://www.ncasi.org/forestry/research/headwater.stm

 
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
  http://www.fertilizer.org/ifa/
 
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
  http://www.isu.edu/departments/bios/Minshall/publications_reports.htm

 
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
  http://www.geog.ouc.bc.ca/physgeog/contents/4e.html

 
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
  http://ib.berkeley.edu/labs/power/index.shtml

 
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.

Learn More
  Link 1

 
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
  http://www.freestone.com/
http://www.flyanglersonline.com/features/greatrivers/ausableny/

 
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.

Learn More
  http://www.mycolog.com/chapter11b.htm

 

G

Genus

A level of taxonomic classification that immediately precedes species.

Learn More
  http://explorers.bishopmuseum.org/sciencegarden/dClassification/naming.html

 
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
  Link 1

 
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.

Learn More
  http://timefold.com/yosemite/parkintro.html

 
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
  http://www.groundwater.org/

 

H

Habitat

Referring to the physical locale of a plant or animal. Not to be confused with niche.

Learn More
  http://www.ossm.edu/biology/ecoln.htm#Living

 
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
  http://museum.gov.ns.ca/mnh/nature/nhns/h6/h6-1.htm

 
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
  http://www.chemsoc.org/viselements/pages/pertable_j.htm
http://www.epa.gov/ebtpages/pollutants.html

 
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
  http://directory.google.com/Top/Business/Chemicals/Herbicides/
http://pmep.cce.cornell.edu/profiles/herb-growthreg/

 
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
  Link 1

 
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
  http://www.unesco.org/science/waterday2000/Cycle.htm

 
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
  Link 1

 
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
  Link 1

 

I

Impoundment

Any standing body of water created by a damming a river.

Learn More
  http://www.tva.gov/
http://www.dams.org/
http://www.who.int/infectious-disease-report/pages/ch9text.html#Anchor5

 
In situ

A Latin word denoting within. For example, macrophytes grow in situ in limestone streams.

Learn More
  Link 1

 

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
  http://www.consecol.org/vol2/iss2/resp2/

 

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
  Link 1
Link 2
Link 3

 
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
  Link 1
Link 2
Link 3

 

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
  Link 1
Link 2

 
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
  http://serc.fiu.edu/periphyton/macrophyte/maclinks.htm
http://www.fish.soton.ac.uk/chalkstream.html

 
Main stem

The final section of river, below which cannot be found any tributaries larger in volume than itself.

Learn More
  Link 1

 
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
  Link 1
Link 2

 
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 and periodic floods that cut off the meander with deposits of soil between the loops of river, creating a standing body of water in the process. In most freestone rivers, meanders are common, while in limestone situations, meanders are less predicable and may not be a regular feature, due to slow currents and low volumes of water.

Learn More
  Link 1

 

N

Niche

The niche is a theoretical concept first fully developed by G. E. Hutchinson and brought forward by numerous other distinguished ecologists. It attempts to define all physical, chemical and biological factors that influence a single organism throughout its life. Energy consumption is also part of the complex equation defining the “essential” niche. This global concept cannot be tested by experimental approach, yet it is a useful notion when considering the interactions of all life forms within a given ecosystem. The statement that no two organisms can occupy the same niche suggests that competition plays a significant role in the interactions between assemblages and communities of organisms. Defining the essential niche of any macro invertebrate is an impossible task, considering its constantly changing environment. This fact, alone adds to the romance and mystery of river ecology.


Learn More
  http://www.geog.ouc.bc.ca/physgeog/contents/9g.html

 
“No Kill” stretch

A portion of a trout stream in which all fish hooked and landed must then be returned back to the water as quickly as possible. This mode of fishing has gained in popularity over the last decade and is now the rule for many stretches of rivers across the country, throughout most of Europe, parts of South America, New Zealand and Australia. No kill fishing helps preserve the balance between prey and predator in the riverain ecosystem (see Keystone species).

Learn More
  http://www.tu.org

 
Non-point source pollution
Pollution that cannot be traced back to any one source (e.g., runoff from roads and residential areas).

Learn More
  http://www.epa.gov/owow/nps/Ecology/chap3.html
 
Nutrient Loading

An excess of dissolved substances in a river that de-regulates the limiting nutrients controlling the amount of bio-productivity of that system. Nutrient loading can result from anthropogenic sources, such as effluent containing phosphate detergents dumped into rivers from sewage treatment plants. Natural sources of nutrient enrichment also exist, as in the case of the Green River in northern Utah. Nitrates and phosphates that were deposited in the strata above the normal level of the river were flooded by the impoundment created by the Flaming Gorge Dam project. As the result, these nutrients now leach into the lake, permitting large assemblages of algae to exist. A portion of these single cell plants are exported to the river below. Filter feeding macro invertebrates there take advantage of this wind-fall, enabling the Green River below the dam to become one of the world’s greatest producers of trout per linear mile (est. 22,000). Similar results occurred with the damming of the Madison River in Montana, and numerous other coldwater fisheries. Negative effects on the growth of macro invertebrates and trout result when nutrient loading over-produces the wrong kinds of algal species (e.g., blue-green), or occurs in warm water situations in which algal blooms literally smother the life forms by depleting the already limited amounts of oxygen during periods of darkness.

Learn More
  http://www.co.missoula.mt.us/measures/nutrient.htm
http://www.umt.edu/biology/flbs/Research/Nutrientloading.htm

 

O

Oligothrophic

A term applied to lakes that are cold water bodies most of the year and which are nutrient poor. Most are located in the northern hemisphere and were created by the retreat of the glaciers during the last ice age. These lakes usually have a low biodiversity index, but can accumulate and support substantial populations of a few species of fish.

Learn More
  http://www.mlswa.org/lkclassif1.htm
http://wow.nrri.umn.edu/wow/under/primer/page16.html

 

P

Pesticide

Any synthetic or natural product designed to have deleterious effects against arthropods of various species. Many plants produce pesticide-like molecules as a defense against insects. The agro-chemical industry has produced numerous compounds that attack biological activities essential to the life of macro invertebrates. Organophosphates (e.g., DDT and the like) are the most widely known of these, and the worldwide misuse of this one compound has induced significant environmental change over the past 50 years. One of the major problems with the indiscriminant use of any pesticide is its penchant for accumulating in the food chains and food webs of aquatic ecosystems, devastating macro invertebrate communities in the process. Rachel Carson’s Silent Spring documents the advent of the age of the use of synthetic insecticides and their deleterious effects on all wildlife.

Learn More
  http://www.epa.gov

 
pH

A chemical measure of acidity. pH is the negative log (base10) of the hydrogen ion concentration, and is expressed as a whole number on a scale ranging from 1 through 14, with 1 being the most acidic, 7 is neutral, and 14 the most basic.

Learn More
  http://www.miamisci.org/ph/
http://www.osearth.com/resources/recall/acidrain.shtml

 
Photic zone

The zone of water through which light penetrates and stimulates photosynthesis. This term is usually reserved for discussions of lakes and the world’s oceans, since most rivers that support trout are transparent, allowing light to reach all the way to the benthic zone.

Learn More
  Link 1
Link 2

 
Pioneer Species

The first species of plant to emerge after clear-cutting or after a natural disaster, such as tornado, flood, fire, or severe drought. These are shade intolerant organisms.

Learn More
  Link 1
Link 2

 
Plankton

Any kind of microscopic aquatic organism, either plant (phytoplankton) or animal (zooplankton). Plankton are mostly consumed by lake dwelling filter feeders (e.g., minnows), and filter feeding macro invertebrate species of tailwater fisheries.

Learn More
  Link 1
Link 2
Link 3

 
Pool

An erosional depression in the bed of a freestone river characterized by deep water, slow currents, and often the presence of a spring hole.

Learn More
  http://wrgis.wr.usgs.gov/docs/parks/noca/sb16river.html

 
Point source pollution
Any pollutant that can be traced back to a single source.

Learn More
  http://bayinfo.tamug.tamu.edu/pspx.html
http://www.soest.hawaii.edu/GG/ASK/waterpol3.html
 
Predation

The act of one animal consuming another.

Learn More
  Link 1

 
Predator

Any animal that catches, then eats its prey. A member of the third or forth trophic level.

Learn More
  http://movies.yahoo.com/shop?d=hv&cf=info&id=1800107656&intl=us
(just kidding!)

 
Primary Consumer

Any animal that eats plants on a regular basis. A member of the second trophic level.

Learn More
  http://www.nhptv.org/natureworks/nwep9a.htm

 

Primary Producer

Any plant with photosynthetic capacity.

Learn More
  Link 1
Link 2
Link 3

 

R

Remediation

The act of repairing a damaged portion of an ecosystem.

Learn More
  Essay on Remediation by John Cairns, Jr.
Link 1

Link 2

 
Resiliency

The ability of a damaged ecosystem to repair itself, if left alone. For example, clear-cutting all trees in a well-defined watershed, then leaving them lie in place was the basis for a simple yet important experiment in the Hubbard Brook watershed of New Hampshire conducted by Dr. Gene Likens, while he was a faculty member at Dartmouth University. The downed trees and under story were sprayed with a mild herbicide for three years after the initial cutting to discourage the growth of seedlings, and then the entire system was left alone and carefully monitored. It is still being studied today as part of a long-term ecological study plan initiated by the National Science Foundation. It was demonstrated that the leaching of nutrients from unprotected soil was accelerated during the first three years, then returned to normal. During the first three years, pioneer species of plants grew out and provided shade for the shade tolerant tree species and held soil in place at the same time. These activities are referred to as ecosystem services. Eventually the trees overshadowed the shade intolerant pioneer species and they died out leaving only the trees. The aquatic conditions of the Hubbard Brook returned to normal after the third year. Resiliency was the term used to describe these events. It was postulated that resiliency of the Hubbard Brook watershed was due to a variety of factors, not the least of which was the fact that tree seeds were long lived in the soil and germinated after the clear-cutting. These studies give hope for other ecosystems damaged by the heavy hand of commercial logging and other forms of encroachment. The intimate connection between river and forest cannot be emphasized enough.


Learn More
  http://www.hubbardbrook.org/

 
Riffle

A geological formation in a freestone river that is relatively resistant to erosion, resulting in shallow, fast flowing water. These regions precede pools, and together help to define the main flow characteristics of the freestone river.

Learn More
  http://wrgis.wr.usgs.gov/docs/parks/noca/sb16river.html

 
Riparian

Referring to rivers.

Learn More
  http://www.amrivers.org/

 
Run Off

Surface water that fails to seep into the ground. runoff occurs when natural absorbers of water, such as tree and shrub roots have been removed from a given location. runoff in suburban areas contains non-point source pollutants (gasoline, crank case oil, herbicides, pesticides, fertilizers, for example) that find their way into riparian systems. Often they drain into impoundments that are used for drinking purposes, raising serious issues of long-term health risks for humans, as well as for all the other living things that depend upon clean water.

Learn More
  http://wwwga.usgs.gov/edu/runoff.html
http://www.bafg.de/grdc.htm

 

S

Salmonid

Any fish species that is a member of the Family Salmonidae (see Appendix).

Learn More
  http://www.tu.org
http://www.fisheries.org

 
Secondary Consumer

Any animal that is a member of the second trophic level of an ecosystem. Usually a predator or scavenger species.

Learn More
  http://www.nhptv.org/natureworks/nwep9a.htm

 
Shade Intolerant

Any plant species that cannot grow under shade conditions. Pioneer species typify this kind of plant

Learn More
  Link 1

 
Shade Tolerant

Any species of plant that can grow under shade conditions. Most tree species are shade tolerant, as are tropical plants that live below the canopy.

Learn More
  http://www.arborday.org

 
Shredder Invertebrate

Any species of aquatic arthropod that can process plant material by shredding it after it falls into the river. However, shredders need the detritus to be microbially processed first before they will take a bite. Shredders are sloppy eaters and send food particles downstream for a filter feeder feast.

Learn More
  http://www.benthos.org

 
Siltation

The process of erosion in which portions of soil from the banks wash into the river. Silt covers macro invertebrates, thus killing them. The single most important cause of siltation is the removal of trees from along the banks of the river.

Learn More
  http://www.epa.gov/305b/2000report/chp2.pdf
http://www.trout.forprod.vt.edu/fish_res/pr_area2.htm

 
Species

A species is a difficult unit of life to describe biologically, except for those organisms that engage in sex. In those cases, their genetics, behavior, and geographic distribution defines the population. Geographic separation and/or the constant pressure exerted on it by mutations within that population leads to the eventual creation of new species by the process of natural selection, whereby the mutant best suited to its new environment stands the best chance of survival. The species concept is the lynch pin upon which the science of biology rests.

Learn More
  http://www.sp2000.org
http://www.all-species.org
http://www.saveamericasforests.org/news/EOWilsonIntro.htm

 
Spring Creek

A riparian ecosystem characterized by low flow rates and cold water that emanates from a spring, and which often harbors numerous macrophyte plant species. The pH of spring creeks vary widely, often approaching that of a limestone situation, but not infrequently reflects conditions of most freestone rivers, where the substrate determines its chemistry.

Learn More
  http://www.flyfishingjournal.com/archives/fa199908_1.htm

 
Spring Hole

The emergence of the aquifer at the surface of the benthic or hyporheic zone of the river, out of which flows cold, un-oxygenated water. Spring holes are refugia for trout and macro invertebrates during periods of drought, floods, and extreme cold when abundant anchor ice forms.

Learn More
  http://wrgis.wr.usgs.gov/docs/parks/noca/sb16river.html

 
Solar Constant

The amount of heat from the sun that strikes the surface of the earth each day expressed as calories per square centimeter of earth surface per minute. The actual amount is 1.94 cal/ cm2/min. Recently, astronomers specializing in solar phenomena have discovered that this “constant” can and does change slightly from moment to moment, perhaps altering the energy budget for the planet and giving rise to small differences that might reflect themselves later in larger ecological change.

Learn More
  http://remotesensing.oma.be/solarconstant/solar.html

 
Solar Radiation

The electromagnetic spectrum encompassing wave lengths in the light and heat range of frequencies arriving at the surface of the earth from the sun. The ozone layer in the stratosphere selects out certain ultraviolet frequencies, allowing the rest to pass onto the earth’s surface. Plants use light for photosynthesis in the visible blue-green region of the electromagnetic spectrum (i.e., 350-500 nanometers in wave length).

Learn More
  http://www.nrel.gov/srrl/

 
Stonefly

Any member of the Order Plecoptera. There are over 1,900 recognized species world wide, with 595 found in North America. Many are scrappers (i.e., algae eaters), while others prefer to eat insects (i.e., entomophagus). They are among the oldest examples of aquatic insects, and the first ones to emerge onto the land were without wings. Stone flies undergo incomplete metamorphosis (see: Developmental Cycle) and can take several years to mature in the stream before hatching.

Learn More
  http://www.mc.edu/campus/users/stark/american.html

 

T

Tailwater fishery

Rivers that pour out of a dam are hard to characterize ecologically since their chemistries depend upon the impoundments above them. In general, they are highly productive, due to the relative constancy of environmental conditions (flow rates, annual temperature fluctuations, pH, nutrient input, etc.). Some of the world’s greatest fisheries are of this type.

Learn More
  http://www.tva.gov
http://www.cbr.washington.edu

 
Tailrace

The portion of a tailwater river immediately downstream from the dam. This area is usually where the highest water pressure is found. Because of this characteristic, it is also the region in which nitrogen saturation occurs. If fish are accidentally caught in the turbines of a power-generating dam and forced through into the tailrace, they often suffer the “bends” and die. This routinely occurs in the West when the salmon fry attempt to negotiate the numerous dams on the Columbia River system in Washington State in their struggle to reach the ocean.

Learn More
  http://www.hq.usace.army.mil/cepa/pubs/may00/may00story8.htm

 
Teleost

Any member of the Class Osteichthyes. Teleosts are bony fishes, in contrast to sharks, skates and rays, which are cartilaginous fishes (Class Condrichthyes).

Learn More
  http://www.liv.ac.uk/~rickl/Fisheries_Web/ichthyology/teleosts.htm

 
Thermal Pollution

An upward change in water temperature, often exceeding the tolerance limits for some forms of aquatic life. If no springs or feeder streams are available to offer temporary refuge from these events, a fish kill may ensue. Thermal pollution is the hallmark of tailwater fisheries not managed for the life forms in the river, but rather only for drinking or irrigation purposes. Enlightened views on water release practices are gradually replacing such outdated thinking, and ecosystem management prevails.

Learn More
  http://www.tu.org

 
Thermal Shock

The sudden release of cold or hot water into a river or stream. The effect is the same; namely severe disturbance of the life forms of that ecosystem.

Learn More
  Link 1

 
Tolerance Limit

The biological expression of an organism to live within certain prescribed physical, chemical, and biological parameters. For aquatic organisms living in cold, highly oxygenated water, the limits for life are defined by the amounts of dissolved oxygen, fluctuations in ambient temperature, and a variety of other related conditions that, taken together characterize the world’s trout rivers. Exceeding a tolerance limit for any one factor effectively eliminates all organisms from that zone that share that characteristic.

Learn More
  Link 1

 
Trophic level

The word “trophic” is Greek, and is a term used to describe the flow of energy through a given ecosystem. In most ecosystems there are four trophic levels. The first is occupied by the primary producers, photosynthetic plants that convert a small portion of the incoming solar energy into edible biomass. The second is occupied by primary consumers that feed on plants. The third is occupied by the secondary consumers, and they feed on primary consumers, either by predation or scavenging dead animal carcasses. The final level, level four, is occupied by the top carnivores, and these predators feed on secondary and primary consumer groups, while some even feed on primary producers (e.g., the grizzly bear is mostly a herbivore, but you couldn’t tell that by looking at one!). The efficiency of the system is at about 10%. That is how much of the available energy is converted to biomass of the next trophic level. The rest, 90%, is dissipated as heat due to metabolism and respiration.

Learn More
  http://www.csuchico.edu/~pmaslin/limno/trophic.html

 

U

Unconfined Aquifer

Porous rock that contains water above impervious rock strata.

Learn More
  http://www.dnr.state.mn.us/groundwater/unconfinedaquifers.html

 
Understory

Shrubs, wild flowers, and bushes that grow on the forest floor. Shade tolerant plant species.

Learn More
  http://www.env.duke.edu/forest/sucession.htm
http://www.ies.org

 

W

Watershed

A precisely defined geographic region through which drains a dendritic (i.e., bifurcating) pattern of waterways (i.e., rivulettes, streams, and rivers). All water falling on the watershed exits at the bottom of a single valley, usually as a full-fledged river, or flows into a lake that has an outlet allowing the river to resume its journey once the lake is full.

Learn More
  http://www.ctic.purdue.edu/KYW/glossary/whatisaws.html
http://www.epa.gov/surf/

 
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