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- Those non-living factors which make up our environment and
which can affect the biotic (living) environment. They can include
such things as climate (wind, moisture, temperature,...), geology
(rocks, minerals), and atmosphere (oxygen, carbon dioxide,...).
- activated sewage sludge
- Activated sewage sludge is a product of a secondary
sewage treatment process. The process utilizes aerobic
microorganisms for to break down organic matter.
- The introduction of oxygen into a system.
- Microorganisms which require free oxygen or air in order to grow and survive.
- An environment which has the presence of oxygen.
- aerobic respiration
- Respiration (utilization of food, i.e. carbohydrates)
which occurs in the presence of oxygen and in which the food has been
completely oxidized to carbon dioxide and water. There is a
release of chemical energy during the process.
- An agitator is a device which stirs or shakes. Its purpose is to create irregular, rapid, or violent movement.
- Algae is a heterogenous group of eukaryotic (see eukaryote) plants. They
photosynthesize, they can be unicellular (one-celled) or multicellular
(many celled), and their tissues are not differentiated into roots,
stem, and leaves. Algae are found in many habitats on the earth
including both land and water, however they are primarily found in fresh
or marine waters. Note: blue-green algae are actually
Cyanobacteria (see cyanobacteria).
- algal bloom
- Algae blooms are a sudden growth of algae in fresh or marine waters (aquatic
ecosystem). Algae blooms generally occur under two conditions.
The first type of algae bloom occurs naturally during spring or early
summer after "turn-over" in the aquatic system leaves the
surface water rich in nutrients. At this time the primary
production (see primary production) exceeds the consumption by aquatic
herbivores such as daphnia, fresh water shrimp, and water fowl
resulting in excessive growth of algae.
The second type of algae bloom occurs as a result of human induced water
pollution. Nutrient enrichment of the surface water, as a result of
nutrient rich runoff from fields, sewage being accidentally or purposely
dumped or leaked into surface waters, and non-point source nutrient rich
runoff, can all induce algal blooms. Both of these blooms are
characteristic symptoms of eutrophication (see eutrophication).
- alkane (paraffins)
- Fairly unreactive, saturated hydrocarbons with the general formula CnH2n+2.
They are found in natural gas and petroleum and form a homologous series
which includes methane (CH4), and ethane (C2H6).
The lower molecular weight members of the series are gases, i.e.
methane, whereas the higher molecular weight members are waxy solids.
- A term used to indicate the immediate surroundings or environment.
Ambient pressure and ambient temperature is the pressure and the
temperature of the surrounding atmosphere and is generally used as a
reference in relation to a specific object or system.
- Amines are an organic compound produced when one or more hydrogen atoms are
replaced by an organic group in ammonia. This occurs during the
decomposition of organic matter.
- ammonia: NH3
- Ammonia is a colourless gas with a strong odour. It is an
important component of the nitrogen cycle and is produced by the
decomposition of organic nitrogen compounds, i.e. when nitrogen gas is reduced to form
ammonia. Nitrification occurs when ammonia is oxidized to form nitrite,
and nitrite is oxidized to form nitrate.
- Anaerobes are organisms which can live or grow in an environment
that does not
contain free oxygen. Facultative anaerobes are normally aerobic
but can respire anaerobically during periods of oxygen shortage, whereas
obligate anaerobes cannot exist in an aerobic (free oxygen) environment.
- An anaerobic environment is one in which free oxygen is absent.
- anaerobic respiration
- A type of respiration in which food, i.e. carbohydrates, is partially oxidized and occurs under
anaerobic conditions. There is a release of chemical energy during
the process, however, because the substrate is never completely oxidized
the energy yield is lower than that during aerobic respiration.
- Anoxic conditions exist where their is an absence or deficiency of oxygen.
Anoxic sediments and bottom waters are commonly produced when there is a
deficiency of oxygen due to high organic productivity and a lack of
oxygen replenishment to the water or sediment. Examples of this
would be in stagnant and/or stratified surface waters.
- Substances that destroy or inhibit the growth of microorganisms, particularly
disease-producing bacteria. Antibiotics are obtained from
microorganisms or synthesized. Overuse of antibiotics can lead to
the development of resistant strains of microorganisms.
- aquatic environment
- An aquatic environment is a habitat
that is composed primarily of water.
- archaebacteria or Archaea
- The domain name Archaebacteria, now known as Archaea, is split
into two kingdoms of organisms: Crenarchaeota and Euryarchaeota.
The domain Archaea contains methanogens (responsible for the production
of methane), sulfur-reducing organisms (responsible for the production
of hydrogen sulfide), and extremophiles.
- An autotroph is an organism that uses carbon dioxide as its main or sole source of carbon.
Biological conservation is active management to ensure the survival of
the maximum diversity of species and the maintenance of genetic variety
within species. The term also implies the maintenance of biosphere
functions, e.g. biogeochemical cycling, without which the basic
resources for life would be lost.
Biological productivity is the productivity of organisms and ecosystems, as defined by primary,
secondary, and community productivities.
Biomass is the total mass of all living organisms (producers,
consumers, and decomposers) present in an ecosystem or at a particular trophic
level in a food-chain, and usually expressed as dry weight or as
the carbon, nitrogen, or calorific content per unit area.
bioreactor (industrial fermenter)
A bioreactor is a large stainless steel tank used to grow
producer microorganisms in the industrial production of enzymes and
other chemicals. An agitator mixes the medium,
which is constantly aerated.
Bioremediation is the use of biological agents
or organisms to reclaim soils and waters polluted by substances hazardous
to human health and /or the environment; it is an extension of biological
treatment processes that have traditionally been used to treat wastes in which
microorganisms typically are used to biodegrade environmental pollutants.
Biosphere is the part of the Earth's environment
in which living organisms are found, and with which they interact to produce a
steady-state system; the part of the earth in which
life can exist; it is the whole of the region of the
earth's surfaces, the sea, and the air that is inhabited by living organisms.
Biotic is any of the factors of an organism's
environment that consist of other living organisms.
Biotic indices are indicator species.
For example, the presence of certain invertebrate groups
in fresh water can be awarded a score that indicates the quality of the
water. A scheme employing biotic indices has a scale ranging from
10 (clean water with diverse fauna) to 0 (grossly polluted water with no
fauna or with only a few anaerobic organisms).
A bloom is a visible
abundance of microorganisms, generally referring to the excessive growth
of algae or cyanobacteria at the surface of a body of water.
- benthic zone
- The benthic zone is the lowest region in surface and marine waters. It
is where the benthos (collection of benthic organisms) exists.
The benthic abyssal region is a region of low productivity because little
light is able to penetrate to this depth.
The benthic littoral region is a shallower benthic region which is well lit
and therefore supports very productive ecosystems.
- In both surface and marine waters, the benthos is the collective term for
the organisms, flora and fauna, which live at the bottom. Those
benthos which attach to or rest on the bottom are referred to as
epifauna, and those which bore or burrow into the sediment are referred
to a infauna.
- biochemical or biological oxygen demand (BOD)
- BOD is the amount of dissolved oxygen used by aerobic and facultative microorganisms to
stabilize organic matter (decompose) in an aquatic environment (includes
sewage). It is used as an indicator of the polluting capacity of
effluent or to measure the amount of organic pollution in water.
It is measured as the weight (mg) of oxygen used (by microorganisms), in
a one litre sample of effluent/water, over a five day period at 20 °C
in the dark.
- Biodegradable is a term used to indicate that a substance is capable of being broken down
by microorganisms into smaller products.
- (biological diversity). Biodiversity, or biological diversity, is the
existence of a wide variety of species (species diversity), or other
taxa of plants, animals, and microorganisms within a natural community
- Species within a particular environment are referred
to as ecological diversity.
- Maintaining a high level of
biodiversity is important for maintaining a stable ecosystem.
Biodiversity includes the aspects of species richness, ecosystem
complexity, and genetic variation.
- A biofilm is a microbial community which resides or lives on a surface, e.g. rock
in a stream, as a microlayer.
- Biogas is a mixture of methane (primarily) and carbon dioxide which is the
result of anaerobic decomposition by methanogenic bacteria of waste
materials such as domestic, industrial, and agricultural sewage.
- biogeochemical (cycle) - (nutrient cycle).
- A biogeochemical cycle is the cyclical movement of elements
between living organisms (the biotic phase) and their nonliving (abiotic)
surroundings (e.g. rocks, water, air). Examples of biogeochemical
cycles are the carbon cycle, nitrogen cycle, oxygen cycle, phosphorus
cycle, and sulfur cycle. It is the movement of chemical elements
from organisms to physical environment to organisms in more or less
- A perfect
cycle, i.e. the nitrogen cycle, has a readily accessible abiotic,
usually gaseous, reservoir and many negative-feedback controls. In
contrast the phosphorus cycle, which has a sedimentary reservoir
accessed only by slow-moving physical processes, has few
- Human activities can disrupt these
cycles, leading to pollution. Theoretically, perfect cycles are
more resilient than imperfect cycles.
- carbon cycle
- The carbon cycle is one of the major cycles of chemical
elements in the environment and involves the movement of carbon through the surface,
interior, and atmosphere of the Earth.
- Carbon exists in
atmospheric gases, in dissolved ions in the hydrosphere, and in solids
as a major component of organic matter and sedimentary rocks.
- Inorganic carbon exchange is mainly between the
atmosphere and hydrosphere.
- The major movement of carbon results
from photosynthesis and respiration (in plants, algae and
cyanobacteria), with exchange between the
biosphere, atmosphere, and hydrosphere.
- carbon dioxide: CO2
- Carbon dioxide is a colourless, odourless gas that is
soluble in water. It is the product of the complete oxidation of carbon and the compound most
involved in the transport of carbon through the carbon cycle.
Carbon dioxide is utilized by autotrophs (plants, algae and
cyanobacteria) in the process of
photosynthesis. The process of respiration, organic
matter decomposition and respiration all produce CO2.
- A catchment is a drainage basin, or watershed
and is the area from which a surface watercourse
derives its water.
- chemical oxygen demand
- Chemical oxygen demand, or COD, indicates how much
oxidizable material there is in a sample
and is used an an indicator of water or effluent quality. Potassium
dichromate is used as the oxidizing agent.
- Chemoautotrophs are organisms that use carbon
dioxide as their main or sole
source of carbon/energy. These
microorganisms obtain energy from the oxidation of inorganic carbon and carbon
- Chemoheterotrophs are organisms that obtain
their carbon for energy chiefly from
- Chemoorganotrophs are organisms that
obtain their energy from the metabolism/oxidation of
- A chemotroph is an organism that obtains its energy from chemical reactions.
- Chlorophyll is the green pigment in plants,
algae and cyanobacteria that functions in photosynthesis by absorbing
radiant energy from the sun.
- Chlorophyta are a large phylum of
green algae in which its members
possess chlorophylls a and b, store food reserves as starch, and have cellulose
- Coliforms or coliform bacteria are gram-negative,
lactose-fermenting, enteric rods, e.g. Escherichia coli (E.coli).
- coliform count
- Coliform count is a count made of the numbers of coliform bacteria present as part of most
standard analyses of water. The number of organisms present is normally
expressed per 100 ml of water, e.g. 10 CFU/100 mL.
- A general term applied to any grouping of populations of different
organisms found living together in a particular environment. The organisms
interact by competition, predation, mutualism,..., and give the
community a structure.
- compensation level or compensation depth
- The depth at which light penetration in aquatic ecosystems is so reduced
that oxygen production by photosynthesis just balances oxygen consumption by
lakes, the depth of effective light penetration, separating the limnetic
and profundal zones.
- Competition is the
interaction between individuals of the same species (intraspecific
competition), or between different species (interspecific competition)
at the same trophic level, in which the growth and survival of one or all
species or individuals is affected adversely. Competition
favors the separation of closely related or otherwise similar species.
- A competitor is an organism that lives in competition
with another organism.
- Compost is a mixture of decaying organic matter, such as vegetation and manure, that
is used as a fertilizer. The organic material is decomposed by
aerobic organisms, mostly fungi and bacteria. Some
decomposition if also carried out by detritivores.
- A consumer in the widest sense
is a heterotrophic organism that feeds on living or dead
organic material. The two main consumer types are the
macroconsumers that include mainly
animals (herbivores, carnivores, and detritivores), that wholly or
partly ingest other living organisms or organic particulate matter;
and the microconsumers such as bacteria and fungi
that feed by breaking down complex organic
- Coprophagous is the ability to grow
or feed on fecal matter, dung or excrement.
- Cyanobacteria is a large and varied group of bacteria
that possess chlorophyll a and
carry out photosynthesis in the presence of light and air,
and produce oxygen. They are a phylum of
photosynthetic bacteria comprising the blue-green bacteria - thus the reason for
formerly being classified as blue-green algae. Cyanobacteria occur in all
aquatic habitats and a few species fix atmospheric nitrogen in the soil
- A genus of crustaceans belonging to the class Branchiopoda and order
Cladocera (water fleas).
- A term that is generally synonymous with microconsumers. In an
ecosystem, decomposer organisms, mainly bacteria and fungi, enable
nutrient recycling by breaking down the complex organic molecules of
dead protoplasm and cell walls into simpler organic and (more
importantly) inorganic molecules which may be used again by primary
producers. Some macroconsumers may play a role in decomposition in
that detritivores, in breaking down litter, speed its bacterial
breakdown. In this sense decomposer has a wider meaning than that
- An organism that obtains energy
from the chemical breakdown of dead organisms or animal or plant wastes.
Decomposers, most of which are bacteria and fungi, secrete enzymes onto
dead matter and then absorb the breakdown products. Many
decomposers are specialized to break down organic materials that are
difficult for other organisms to digest. Decomposers fulfill a
vital role in the ecosystem, returning the constituents of organic
matter to the environment in inorganic form so that they can again be
assimilated by plants.
- organisms, often bacteria or
fungi, in a community that convert dead organic matter into inorganic
The chemical breakdown of organic matter into its constituents by the
action of decomposers.
type of organic chemical reaction in which a compound is converted into
a simpler compound in stages.
- degradative succession
- heterotrophic succession. A succession that occurs on
dead organic matter over a relatively short time-scale (months to
years). Detrivores feed in sequence, each group releasing
nutrients that are utilized by the next group in the sequence until the
resources are exhausted.
conversion of nitrate or nitrite to gaseous products, chiefly nitrogen
(N2) and/or nitrous oxide (N2O), by certain types
of bacteria (denitrifying bacteria). denitrification occurs mainly
under anaerobic or micro-aerobic conditions.
- A chemical process in which
nitrates in the soil are reduced to molecular nitrogen, which is
released into the atmosphere. This process is effected by
denitrifying bacteria (e.g. Pseudomonas denitificans), which use
nitrates as a source of energy for other chemical reactions in a manner
similar to respiration in other organisms.
- the formation of gaseous
nitrogen or gaseous nitrogen oxides from nitrate or nitrite by
- denitrifying bacteria
which can carry out denitrification; they occur, for example, in soil
and in freshwater and marine environments, and include, for example,
certain species of Bacillus, Hyphomicrobium, Paracoccus,
Pseudomonas, and Thiobacillus.
mainly freshwater green algae that belong to the class Desmidioideae.
Like Spirogyra, they have an elabourate chloroplast.
- detritus feeder. A heterotrophic animal that feeds on dead
- the dead material is most typically of plant
origin, but it may include the dead remains of small animals.
Since this material may also be digested by decomposer organisms (fungi
and bacteria) and forms the habitat for other organisms (e.g. nematode
worms and small insects), these too will form part of the typical
- An animal that feeds on
detritus. Detritivores play an important role in the breakdown of
organic matter from decomposing animals and plants.
- an organism that feeds on
detritus; an organisms that feeds on organic wastes and dead organisms.
- Litter formed from fragments of dead material (e.g. leaf
litter, dung, molted feathers, and corpses). In aquatic habitats,
detritus provides habitats equivalent to those which occur in soil
- Particles of organic material
derived from dead and decomposing organisms, resulting from the
activities of the decomposers.
- waste matter and biomass
produced from decompositional processes
- A microscopic alga, belonging to the division Bacillariophyta, in which
the cell wall is composed of silica and consists of two halves, one of
which overlaps the other like the lid of a box. Most diatoms are
unicellular, but some are colonial or filamentous. Most are
photosynthetic, but some species live heterotrophically among decaying
unicellular algae having a cell
wall composed of silica, the skeleton of which persists after the death
of the organism.
- An organism capable of utilizing (fixing) atmospheric nitrogen.
- differential resource
- resource partitioning. The situation in
which ecologically similar species sharing the same habitat exploit
different resources, or the same resources but in different ways,
thereby avoiding competition.
movement of molecules or ions from a region of higher to one of lower
solute concentration as a result of their random thermal movement.
The process by which different
substances mix as a result of the random motions of their component
atoms, molecules, and ions. In gases, all the components are
perfectly miscible with each other and mixing ultimately becomes nearly
uniform, though slightly affected by gravity.
to a lake in which two seasonal periods of free circulation occur, as is
typical of lakes in mid-latitude climates. In summer, thermal
stratification occurs as surface waters are warmed and cease to mix with
the denser, colder, deep waters. In winter, when they cool to
below 4 °C, surface waters expand, so becoming less dense than warmer
waters beneath them, giving a reverse stratification. Free
circulation through the depth of the lake is possible only in spring,
when the surface temperature rises to above 4 °C, and the water becomes
heavier than that beneath and so sinks and mixes, and in autumn, when
the surface (epilimnion) waters cool to the temperature of the deep (hypolimnion)
A lake that is stratified by a
thermocline that is not permanent but is turned over twice during one
year. The thermocline is disrupted due to seasonal changes in the
climate. A meromictic lake is one in which there is a permanent
- An order of protozoans that are heterotrophs but closely allied to brown
algae and diatoms. Moist are planktonic, some in fresh water but
most in marine environments, and some live in symbiosis with animals
with which they exchange nutrients. Some are colonial.
- algae of the class Pyrrhophyta,
primarily unicellular marine organisms, possessing two unequal flagella.
- A measure of the water flow, expressed as volume per unit time, at a
particular point (e.g. a river gauging station, sewage works, or
groundwater abstraction well).
- dissolved oxygen level - DO.
- the concentration of oxygen held in solution in
water Usually it is measured in mg/L (sometimes in mg/m3) or
expressed as a percentage of the saturation value for a given water
temperature. The solubility of oxygen varies inversely with
temperature; this is important, because the warmer the water the larger
the proportion of dissolved oxygen that is used by poikilotherms.
The dissolved oxygen level is an important first indicator of water
quality. In general, oxygen levels decline as pollution increases.
- Most simply, the species richness of a community or area, though it provides
a more useful measure of community characteristics when it is combined
with an assessment of the relative abundance of species present.
Diversity in ecosystems has been equated classically with stability and
- the heterogeneity of a system
- the variety of different types of organisms occurring together in a
- diversity index
mathematical expression of the species diversity of a given community or
area, which includes due allowance for the relative abundance of
different species present. Such indices are generally considered
an important means for comparisons of community structure and stability.
A different and specialized case of a diversity index is the biotic
index used in water-pollution studies.
- a mathematical measure which
describes the species richness and apportionment of species within the
to a lake that is usually shallow, rich in humus giving its water a
brown colour, with variable amounts of nutrients, and with the deeper
water often depleted of oxygen. A dystrophic lake was proposed as
one of three categories of standing water, the others being described as oligotrophic and eutrophic, with mesotrophic water comprising an
- A term used to describe a discrete unit that consists of
living and non-living parts, interacting to form a stable system.
Fundamental concepts include the flow of energy via food-chains and
food-webs, and the cycling of nutrients biogeochemically.
a functional self-supporting
system that includes the organisms in a natural community and their
- the liquid
discharge from sewage treatment and industrial plants.
- endorheic lake
lake that loses water only by evaporation, i.e. no stream flows from it.
complete range of external conditions, physical and biological, in which
an organism lives. Environment includes social, cultural, and, for
humans, economical and political considerations, as well as the more
usually understood features such as soil, climate, and food supply.
- environmental impact
- EIA, environmental impact statement
- An attempt
to identify and predict the impact on the biogeophysical environment and
on human health and well-being of proposed industrial developments,
projects, or legislation. EIA also aims to devise early
comprehended, universally applicable schemes for communicating the
results of the assessment.
- The sum total of the environmental limiting
factors, both biotic and abiotic, which together act to prevent the
biotic potential of an organism from being realized. Such factors
include the availability of essential resources (e.g. food, oxygen, and
water), predation, disease, the accumulation of toxic metabolic wastes,
and, in some species, behavioral changes due to stress caused by
- Benthic organisms that live on the surface of the seabed, either
attached to objects on the bottom or free-moving. They are
characteristic of the intertidal zone.
upper, warm, circulating water in a thermally stratified lake in
summer. Usually it forms a layer that is thin compared to the
- the warm layer of an aquatic
environment above the thermocline.
- The organisms (zooneuston) living in the upper part of the surface film of
- estuarine waters
- estuary. A coastal body of water which has a free connection with
the open sea and where fresh water, derived from land drainage, is mixed
with sea water.
archaea. The single kingdom of the domain bacteria, which contains
the true bacteria.
- prokaryotes other than
organism whose cells have a distinct nucleus enveloped by a double
membrane, and other features including double-membraned mitochondria and
80S ribosomes in the fluid of the cytoplasm (i.e. all protists, fungi,
plants, and animals).
- cellular organisms having a
membrane-bound nucleus within which the genome of the cell is stored as
chromosomes composed of DNA; eukaryotic organisms include algae, fungi,
protozoa, plants, and animals.
- eulittoral zone
habitat formed on the lower shore of an aquatic ecosystem, below the
- euphotic depth
or euphotic zone
- the top layer of water, through which
sufficient light penetrates to support the growth of photosynthetic
- In a lake, the depth at which
net photosynthesis (i.e. carbon dioxide uptake by photosynthesis minus
carbon dioxide release by respiration occurs in a light intensity about
1 % of that at the surface.
- The upper, illuminated zone of
aquatic ecosystems; it is above the compensation level and therefore the
zone of effective photosynthesis. In freshwater ecosystems it is
subdivided into littoral (shallow edge) and limnetic zones.
archaea. The more derived of the two kingdoms of Archaea,
comprising a broad range of phenotypes including methanogens, halophiles,
and sulfur-reducing organisms.
to tolerate a wide range of concentrations of oxygen.
applied to nutrient rich waters with high primary productivity but now
also applied to soils. Typically, eutrophic lakes are shallow,
with a dense plankton population and well-developed littoral vegetation.
The high organic content may mean that in summer, when there is
stagnation caused by thermal stratification, oxygen supplies in the
hypolimnion become limiting for some fish species (e.g. trout).
- containing high-nutrient
concentrations, such as a eutrophic lake with high phosphate
concentration that will support excessive algal blooms
- Defined as an increase in the nutrient status of natural waters that
causes accelerated growth of algae or water plants, depletion of
dissolved oxygen, increased turbidity, and general degradation of water
quality. The levels of N required to induce eutrophication in
fresh and estuarine waters are much lower than the values associated
with drinking water contamination. Although estimates vary and
depend considerably on the N:P ratio in the water, concentrations of
0.5-1.0 mg N/L are commonly used as threshold values for eutrophication.
Waters are considered to be eutrophic when: nutrient status is
high, i.e. Total P = > 30 µg/L, Total N = > 500 µg/L, algal
blooms and biomass are common to high, i.e. chlorophyll = >8 mg/L,
aquatic diversity is low, dissolved oxygen is low, i.e. < 10
saturation %, and turbidity is < 2 m (Secchi disk transparency).
(Soils and Environmental Quality. Pierzynski, Sims, and Vance
- The process of nutrient
enrichment (usually by nitrates and phosphates) in aquatic ecosystems,
such that the productivity of the system ceases to be limited by the
availability of nutrients. It occurs naturally over geological
time, but may be accelerated by human activities (e.g. sewage disposal
or land drainage); such activities are sometimes termed cultural
eutrophication. The rapid increase in nutrient levels stimulates
algal blooms. On death, bacterial decomposition of the excess
algae may deplete oxygen levels seriously. this is especially
critical in thermally stratified lakes, since the decaying algal
material typically sinks to the hypolimnion where, in the short term,
oxygen replenishment is impossible. The extremely low oxygen
concentrations that result may lead to the death of fish, creating a
further oxygen demand, and so leading to further deaths.
- the enrichment of natural
waters with inorganic materials, especially nitrogen and phosphorus
compounds, that support the excessive growth of photosynthetic
- Applied to an environment in which the circulation of water is restricted,
leading to reduced oxygen levels or anaerobic conditions in the water.
Such conditions may develop in swamps, barred basins, stratified lakes,
and fiords. Euxinic sediments are those deposited in such
conditions, and are usually black and organic rich.
- exorheic lake
- A lake that has one or more outflow streams.
- extracellular compound
- Something which promotes an action.
- Applied to organisms that are able to adopt an alternative mode of living.
for example, a facultative anaerobe is an aerobic organism that can also
grow under anaerobic conditions.
- The animal life of a region or geological period.
- feedback loop
mechanism. A control device in a system. Homeostatic systems
have numerous negative-feedback mechanisms which tend to counterbalance
positive changes and so maintain stability. For example,
denitrifying bacteria counteract the effects of nitrogen-fixing
bacteria. Positive feedback reinforces change and in natural
systems may result in radical environmental alteration.
with a nutrient solution, e.g. the water may contain nitrogen,
phosphorus, and potassium, and micronutrients
- a mass of
microorganisms cemented together in a slime produced by certain
bacteria, usually found in waste treatment plants.
- All the plant species that make up the vegetation of a given area.
- fresh water
- Water containing little or no chlorine. According to the Venice system,
which classifies brackish waters by their percentage chlorine content,
fresh water contains 0.03 per cent or less of chlorine. - lakes, ponds, swamps, springs,
streams, and rivers.
- gaining stream
stream. A stream that receives water emerging from a submerged
spring or other groundwater seepage which adds to its overall flow.
- gas vacuole
- A small, gas-filled vesicle, numbers of which are found in certain aquatic
bacteria and cyanobacteria. Their function appears to be that of
giving buoyancy to the cells.
- organisms that
prey upon primary producers; protozoan predators that consume bacteria
indiscriminately; filter-feeding zooplankton.
- gross primary production
- total amount of organic matter produced in an ecosystem.
mud. a rapidly accumulating, organic, muddy deposit,
characteristic of eutrophic lakes. The precise nature of gyttja
varies with the producer organisms involved, which include small algae
location where living organisms occur.
measure of the ability of water to form a carbonic scale when boiled, or
to prevent the sudsing of soap. Permanent hardness is due mainly
to dissolved calcium and magnesium sulfate or chloride; the bicarbonate
ion causes temporary hardness. Dissolved carbon dioxide and the
weathering of carbonate rocks are the main sources of hardness in water.
plant typical of marshy or lake-edge environments, in which the
perennating organ lies in soil or mud below the water level, but the
arial shoots protrude above the water, e.g. the common reed.
- A heterotroph that obtains energy by feeding on primary producers,
usually green plants.
organisms that is unable to manufacture its own food from simple
chemical compounds and therefore consumes other organisms, living or
dead, as its main or sole source of carbon.
- organisms requiring organic
compounds for growth and reproduction, the organic compounds serve as
sources of carbon and energy.
to lakes in which the water turns over at least once a year.
chemical reaction in which water combines with another substance.
naturally occurring compound that contains carbon and hydrogen.
Hydrocarbon may be gaseous, solid, or liquid, and include natural gas,
bitumens, and petroleum.
- The study of the hydrologic cycle; this involves aspects of geology,
oceanography, and meteorology, but emphasizes the study of bodies of
surface water on land and how they change with time.
- A plant that is adapted morphologically and/or physiologically to grow in
water or very wet environments. Adaptations include the
development of finely divided submerged leaves, large floating leaves,
the presence of aerenchyma, and the reduction of root systems. The
perennating bud lies at the bottom of fairly open water. With the
leaves submerged or floating, only the inflorescence protrudes above the
- The total body of water which exists on or close to the surface of the
- the aqueous envelope of the
earth, including bodies of water and aqueous vapor in the atmosphere.
- The lower, cooler, non-circulating water in a thermally stratified lake in
summer. If, as often occurs, the thermocline is below the
compensation level, the dissolved oxygen supply of the hypolimnion
depletes gradually; replenishment by photosynthesis and by contact with
the atmosphere is prevented. Re-oxygenation is possible only when
the thermal stratification breaks down in autumn.
- the deeper, colder layer of an
aquatic environment; the water layer below the thermocline.
- The organisms living in the lower part of the surface film of water.
- Benthic organisms that dig into the sea bed or construct
tubes or burrows. They are most common in the subtidal and deeper
- intracellular product
- indicator organism
- an organism used to identify a particular condition, such as Escherichia
coli as an indicator of fecal contamination.
- native to a particular habitat
- kettle hole, kettle lake
- A depression in the surface of glacial drift (especially
ablation or kettle moraine), which results from the melting of an
included stagnant ice mass. It may be filled with water to form a
- labyrinth fish
that have accessory respiratory organs in the gill chambers, enabling
them to utilize atmospheric oxygen when necessary.
solution formed when water percolates through a permeable medium.
When derived from solid waste, in some cases the leachate may be toxic
or carry bacteria.
to a freshwater habitat characterized by calm or standing water (e.g.
lakes, ponds, swamps, and bogs).
- Liebig's law of the
- The concept first stated by J. von Liebig in 1840,
that the rate of growth of a plant, the size to which it grows, and its
overall health depend on the amount of the scarcest of its essential
nutrients that is available to it. This concept is now broadened
into a general model of limiting factors for all organisms, including
the limiting effects of excesses of chemical nutrients and other
- limiting factor
factor. Defined originally as whichever essential material is
available in an amount most closely approaching the critical minimum
needed, but now used more generally to describe any environmental
condition or set of conditions that approaches most nearly the limits
(maximum and minimum) of tolerance for a given organism.
- limnetic zone
zone. The area in more extensive and deeper fresh water ecosystems
which lies above the compensation level and beyond the littoral
(lake-edge) zone. This zone is mainly inhabited by plankton and
nekton with occasional neuston species. The limnetic and littoral
zones together comprise the euphotic or well-illuminated zone. In
very small and shallow lakes or ponds the limnetic zone may be absent.
- in lakes, the portion of the
water column excluding the littoral zone where primary productivity
study of freshwater ecosystems.
to organisms that thrive in ponds or lakes.
organism that obtains energy from the oxidation of inorganic compounds
- microorganisms that live in and
obtain energy from the oxidation of inorganic matter; chemoautotrophs.
to the shore.
- littoral fish
fish that are found along the shores of a lake from the edge of the
water down to the limits of rooted vegetation.
- littoral zone
area in shallow fresh water and around lake shores, where light
penetration extends to the bottom sediments, giving a zone colonized by
- situated or growing on or near
the shore; the region between the high and low tide marks
- logistic equation
- A mathematical description of growth rates for a simple population in a
confined space with limited resources. The equation summarizes the
interaction of biotic potential with environmental resources, as seen in
populations showing the S-shaped growth curve, as: dN/dt = rN(N-K)/K
where N is the number of individuals in the population, t is time, r is
the biotic potential of the organism concerned, and K is the saturation
value or carrying capacity for that organism in that environment.
The resulting growth rate or logistic curve is a parabola, while the
graph for organism numbers over time is sigmoidal.
to a freshwater habitat characterized by running water (e.g. springs,
rivers, and streams).
- man-induced turnover
- The additional flow of an element through the active part of
a biogeochemical cycle, which results from human activity. For
example, by burning fossil fuels human add an extra 5 billion tonnes per
year of carbon to the turnover of the carbon cycle, which is naturally
about 75 billion tonnes per year.
more or less permanently wet area of mineral soil, as opposed to a peaty
area, e.g. around the edge of a lake or on a flood-plain of a river.
Colloquially, marsh is often used interchangeably with swamp and bog.
- A meromictic lake is one in which there is a permanent stratification,
i.e. no seasonal turnover as in a dimictic lake.
zooplankton, i.e. the larval stages of other organisms.
- Applied to waters having levels of plant nutrients intermediate between
those of oligotrophic and eutrophic waters.
part of a water column where the thermocline and pycnocline are
colourless odourless gas, CH4. Methane is the simplest
hydrocarbon, being the first member of the "alkane series. It
is the main constituent of natural gas and as such is an important raw
material for producing other organic compounds. It can be
converted into methanol by catalytic oxidation.
- The simplest hydrocarbon
compound, which is released as a gaseous by-product of the metabolic
activity of certain bacteria. The principal sources of atmospheric
methane are swamps, marshes, and natural wetlands , and paddy-rice
fields. Methane is an important greenhouse gas.
of various archaebacteria that produce methane. They include such
genera as Methanobacillus and Methanothrix.
Methanogens are obligate anaerobes found in oxygen deficient
environments, such as marshes, swamps, sludge (formed during
"sewage treatment), and the digestive system of ruminants.
They mostly obtain their energy by reducing carbon dioxide and oxidizing
hydrogen, with the production of methane. Formate, methanol, or
acetate may also be used as substrates by certain methanogens.
Methanogenic bacteria are important in the production of
- A single-celled organism,
belonging to domain Archaea, that produces methane gas as a product of
- methane-producing prokaryotes;
a group of archaebacteria capable of reducing carbon dioxide or
low-molecular-weight fatty acids to produce methane.
bacterium that can use methane as a nutrient.
organism that can use (as its sole source of carbon and energy) organic
compounds that contain only one carbon atom (i.e. compounds such as
methane and methanol).
to an environment in which the concentration of oxygen is less than that
to an organism that grows best under micro-aerobic conditions.
or pertaining to microorganisms.
animal which feeds on microorganisms.
a microscopic organism. The term is usually taken to include only
those organisms studied in microbiology (i.e. bacteria, fungi,
microscopic algae, protozoa, and viruses), thus excluding other
microscopic organisms such as eelworms and rotifers.
- microscopic organisms,
including algae, bacteria, fungi, protozoa, and viruses.
conversion of organic tissues to an inorganic state as a result of
decomposition by microorganisms.
- the microbial breakdown of
organic materials into inorganic materials brought about mainly by
organism in whose mode of nutrition both organic and inorganic compounds
are used as sources of carbon and/or energy.
- organisms capable of utilizing
both autotrophic and heterotrophic metabolic processes, e.g. the
concomitant use of organic compounds as sources of carbon and light as a
source of energy.
member of a phylum (Mollusca) of invertebrate animals, most of them
aquatic, comprising classes which are morphologically quite diverse.
to lakes in which only one seasonal period of free circulation occurs.
In cold monomictic lakes, typical of polar latitudes, the seasonal
overturn occurs briefly in summer and the water temperature never rises
above 4 °C, so inducing density stratification. In warm
monomictic lakes, typical of warm temperate or subtropical regions, the
seasonal overturn occurs in winter. At other times thermal
stratification, with the formation of a distinct epilimnion, prevents
free circulation through the depth of the lake.
- Highly decomposed organic matter in which original plant material cannot
- Farmyard manure composed of animal feces and
urine mixed with straw and highly decomposed.
stable condition in which two organisms of different species live in
close physical association, each organisms deriving some benefit from
the association; symbiosis.
- natural gas
relationship between two different microbial populations characterized
by the lack of any recognizable interaction.
- net primary production
of organic carbon in the form of biomass and soluble metabolites
available for heterotrophic consumers in terrestrial and aquatic
process in which ammonia is oxidized to nitrite and nitrite to nitrate;
a process primarily carried out by the strictly aerobic,
chemolithotrophic bacteria of the family Nitrobacteraceae.
- nitrifying bacteria
- Nitrobacteraceae; gram-negative, obligately aerobic, chemolithotrophic
bacteria occurring in aquatic environments and in soil that oxidize
ammonia to nitrite or nitrite to nitrate.
- nitrogen cycle
- nitrogen fixation
reduction of gaseous nitrogen to ammonia, carried out by certain
- dinitrogen oxide. A colourless gas, N2O.
It is soluble is water.
- obligate aerobes
- organisms that grow only under aerobic conditions, i.e. in the presence of air or oxygen.
- obligate anaerobes
that cannot use molecular oxygen; organisms that grow only under
anaerobic conditions, i.e. in the absence of air or oxygen; organisms
that cannot carry out respiratory metabolism.
- lakes and other bodies of water that are poor in those nutrients that
support the growth of aerobic, photosynthetic organisms,; microorganisms
that grow at very low nutrient concentrations.
- organic matter
- oxidation pond
- a method of aerobic waste
disposal employing biodegradation by aerobic and facultative
microorganisms growing in a standing water body.
- oxygen cycle
- P/R ratio
relationship between gross photosynthesis and rate of community
that live on or in the tissues of another living organism, the host,
from which they derive their nutrients.
- an interactive relationship between two organisms or populations in
which one is harmed and the other benefits; generally, the population
that benefits, the parasite, is smaller than the population that is
capable of causing disease in animals, plants, or microorganisms
- phosphorus cycle
whose source of energy is light and whose source of carbon is carbon
dioxide; characteristic of plants, algae and some prokaryotes.
- organisms that obtain energy from light but require exogenous organic
compounds for growth.
process in which radiant (light) energy is absorbed by specialized
pigments of a cell and is subsequently converted to chemical energy; the
ATP formed in the light reaction is used to drive the fixation of carbon
dioxide, with the production of organic matter.
whose sole or principal primary source of energy is light; organisms
capable of photophosphorylation.
- passively floating or weakly motile photosynthetic aquatic organisms,
primarily cyanobacteria and algae.
- collectively, all microorganisms and invertebrates that passively drift in lakes and oceans.
- a mode of life in which food is primarily obtained by killing and
consuming animals; an interaction between organisms in which one
benefits and one is harmed, based on the ingestion of the smaller
organisms, the prey, by the larger organisms, the predator.
- organisms that practice predation.
animal taken by a predator for food.
- primary productivity
- primary producer
- organisms capable of converting carbon dioxide to organic
carbon, including photoautotrophs and chemoautotrophs.
- profundal zone
- in lakes, the portion of the water column where respiration exceeds primary
- synergism; a nonobligatory relationship between two microbial
populations in which both populations benefit.
- a chemical that is totally resistant to microbial attack.
- the act of reclaiming or improving an undesirable state.
- Secchi disk transparency test
- secondary sewage treatment
- the treatment of the liquid portion of sewage
containing dissolved organic matter, using microorganisms to degrade the
organic matter , using microorganisms to degrade the organic matter that
is mineralized or converted to removable solids.
- inherent capability of natural waters to cleanse themselves of
pollutants based on biogeochemical cycling activities and
interpopulation relationships of indigenous microbial populations.
- sulfur cycle
cycle mediated by microorganisms that changes the oxidation state of
sulfur within various compounds.
- an obligatory interactive association between members of two
populations, producing a stable condition in which the two organisms
live together in close physical proximity to their mutual advantage.
- tertiary sewage treatment
sewage treatment process that follows a secondary process, aimed at
removing nonbiodegradable organic pollutants and mineral nutrients.
- thermal stratification
- division of temperate lakes into an epilimnion, thermocline, and
hypolimnion, subject to seasonal change; zonation of lakes based on
temperature where warm and cold water masses do not mix.
- zone of
water characterized by a rapid decrease in temperature, with little
mixing of water across it.
- total suspended solids
- trickling filter system
simple, film-flow aerobic sewage treatment system; the sewage is
distributed over a porous bed coated with bacterial growth that
mineralizes the dissolved organic nutrients.
- cloudiness or opacity of a suspension.
- ultraviolet light (UV)
- short wavelength electromagnetic radiation in the range of 100 - 400 nm.
- volatile organic chemical (VOC)
- organic compound that vaporizes into the atmosphere.
- a synthetic product not formed by natural biosynthetic processes; a foreign substance or poison.