PB-229 803 GLOSSARY OF AQUATIC ECOLOGICAL TERMS Environmental Protection Agency February 1972 DQcuwi£MT COLLECT 772 DISTRIBUTED BY: KM National Technical Information Service U. S. DEPARTMENT OF COMMERCE ru ^= m o m _D m □ □ r-=) a MBL/WH( ^^m^- m □ ^^"^» B GLOSSARY OF AQUATIC ECOLOGICAL TERMS compiled by John E. Matthews Aquatic Biologist Reproduced by NATIONAL TECHNICAL INFORMATION SERVICE US Department of Commerce Sptinofield, VA. 22)51 Manpower Development Branch Air and Water Programs Division Region VI Environmental Protection Agency Ada, Oklahoma 74820 September 1969 Revised February 1972 (I PREFACE This Glossary is intended to provide familiarity and under- standing of technical terminology specific to the discipline of aquatic ecology and will serve as a convenient reference for all professionally trained persons concerned with water pollution control. Definitions have been carefully reviewed to assure accord with current professional usuage. Appreciation is tendered to biologists of the following Environmental Protection Agency activities for this service: Robert S. Kerr Water Research Center, Ada, Oklahoma; National Field Investigations Center, National Training Center, Analytical Quality Control Laboratory, Cincinnati, Ohio; National Water Quality Laboratory, Duluth, Minnesota; National Marine Water Quality Laboratory, West Kingston, Rhode Island. Terms specifically identifying or describing organisms have generally been excluded from this work. For this information the reader is referred to the selected references presented in the appendix. Glossaries of terminology related to other disciplines concerned with water pollution control are also listed in the appendix. Terms underscored in a definition are separately defined in this Glossary. Where appropriate, closely associated or related terms are cited parenthetically, (See ), following the definition. Specific synonyms are noted, in parentheses, with the listed word. John E, Matthews A-/ ABYSSAL ZONE All of a sea, or a very deep lake below the bathyal zone. The primary energy source for this region lies far above in the euphotic zone; density of life depends on the amount of organic material that settles from the euphotic zone. (See Hadal Zone) ACCLIMATION Physiological and behavioral adjustments of an organism in response to a change in environment, (See Adaptation) ACCLIMATIZATION Acclimation of a particular species over several generations in response to marked environmental changes. ACUTE TOXICITY ACTINOMYCETES Any toxic effect that is produced within a short period of time, usually 24-96 hours. Although the effect most frequently considered is mortality, the end result of acute toxicity is not necessarily death. Any harmful biological effect may be the result. (See Chronic Toxicity, Direct Toxicity) Filamentous microorganisms intermediate between the fungi and bacteria, although more closely related to the bacteria. These organisms are widely distributed in soils and are often conspicuous in lake and river muds. They are often associated with taste and odor problems in water supplies. A-2 ADAPTATION Change in the structure, form or habits of an organism to better fit changed or existing environmental conditions. (See Acclimation) AEROBIC Refers to life or processes occurring only in the presence of free oxygen; refers to a condition characterized by an excess of free oxygen in the aquatic environment. (See Anaerobic) ALGAE (Alga) Simple plants, many microscopic, containing chlorophyll. Algae form the base of the food chain in aquatic environments. Some species may create a nuisance when environmental conditions are suitable for prolific growth. ALLOCHTHONOUS Pertaining to those substances, materials or organisms in a waterway which originate outside and are brought into the waterway. (See Autochthonous ^ ALLUVIAL Pertaining to material that is transported and deposited by running water. ALLUVIAL FAN (Delta) ANABOLISM Synthesis or manufacture of organic compounds within an organism. (See Metabolism) A- 3 ANADROMOUS Pertaining to fishes that spend most of their life in salt water but enter freshwater to spawn; e.g., salmon, shad, striped bass, etc. (See Catadromous) ANAEROBIC Refers to life or processes occurring in the absence of free oxygen; refers to conditions characterized by the absence of free oxygen. (See Aerobic) ANTAGONISM Reduction of the effect of one substance because of the introduction or presence of another substance; e.g., one substance may hinder, or counteract, the toxic influence of another. (See Synergism) APHOTIC ZONE That portion of a body of water to which light does not penetrate with sufficient intensity to have any biological significance. (See Euphotic Zone) AQUATIC VASCULAR PLANTS (Higher Aquatic Plants) ARTIFICIAL SUBSTRATE A device placed in the water (for a specified period of time) that provides living spaces for a multiplicity of organisms; e.g., glass slides, concrete blocks, multiplate samplers, rock baskets, etc. The primary purpose of artificial substrates is to allow the investi- gator to collect organisms in areas where the physical habitat is limiting or cannot be adequately sampled using conventional methods. A-4 ASSIMILATION 1. Removal of dissolved or suspended materials from a water mass by biological, chemical and physical processes; 2. Conversion or incorporation of absorbed nutrients into body substances. (See Synthesis) ASSOCIATION All organisms occupying a given habitat. ATOLL Large, thick, coral mass encircling a lagoon in tropical oceans; cometimes portions of the reef become built up with sand, silt, soil and vegetation to become an island. (See Barrier Reef, Fringing Reef) AUFWUCHS (Periphyton) AUTOCHTHONOUS Pertaining to those substances, materials, or organisms originating within a particular waterway and remaining in that waterway. (See Allochthonous) AUTOTROPHIC (Holophytic) Self nourishing; denoting those organisms that do not require an external source of organic material but can utilize light energy and manufacture their own food from inorganic materials; e.g., green plants, pigmented flagellates. (See Heterotrophic) B-A BACTERIA Microscopic, single-celled or noncellular plants, usually saprophytic or parasitic. BARRIER BEACH A ridge of deposits separated from the mainland by an interval of water. BARRIER REEF Large, thick, coral mass more or less surrounding an island or paralleling the mainland shore in tropical areas; separated from the land mass by a lagoon. (See Atoll, Fringing Reef) BATHYAL ZONE That region of the sea that extends from the euphotic zone to the bottom of the continental slope. Density of life in this zone depends on organic material settling from the euphotic zone and is generally inversely proportional to the depth. BEACH The zone of demarcation between land and water of lakes, seas, etc.; covered by sand, gravel or larger rock fragments. BENTHIC REGION The bottom of a waterway; the substratum that supports the benthos . B-2 BENTHOS Organisms growing on or associated principally with the bottom of waterways. These include: (1) sessile animals such as sponges, barnacles, mussels, oysters, worms, and attached algae; (2) creeping forms such as snails, worms and insects; (3) burrowing forms, which include clams, worms, and some insects; and (4) fish whose habits are more closely associated with the benthic region than other zones; e.g., flounders. BIOASSAY A determination of the biological effect of some substance, factor or condition employing living organisms or cells as the indicator. BIOCOENOSIS The plants and animals comprising a community. BIOLOGICAL CONTROL 1. Use of natural predators, parasites or viruses to reduce or eliminate pest organisms; e.g., use of gambusia to feed on mosquito larvae; 2. Control of organisms by interference with their physiological processes; e.g., sterilization of male flies. BIOLOGICAL MAGNIFICATION The ability of certain organisms to remove from the environment and store in their tissues substances present at nontoxic levels in the surrounding water. The concentration of these substances becomes greater each higher step in the food chain. (See Enrichment Factor) B-3 BIOMASS The total amount of living material in a given habitat or area; or, an expression dealing with the total weight of a given population of organisms. BIOMONITORING 1. Continuous surveillance of an effluent (or dilution thereof) by using living organisms to test its suitability for discharge into a receiving water. 2. Use of living organisms to test the quality of a receiving water downstream from a waste discharge. (See Bioassay) BIOSTIMULATION A general term used to describe the complex set of factors involved in the growth of algae (and other organisms) in a receiving water due to the addition of nutrients. BIOTA All life of a region. BIOTIC FACTORS (Biological Factors) In ecology, those environmental factors which are the result of living organisms and their activities; distinct from physical and chemical factors; e.g., competition, predation, etc. (See Ecological Factor) BIOTIC POTENTIAL The inherent capability of an animal to multiply in an unrestricted environment. (See Environmental Resistance) B-4 BIOTOPE (Habitat) BLOODWORMS Midge fly larvae . Many of the species have hemoglobin in the blood causing a red color and are often associated with rich organic deposits. Also, the common name for certain of the marine segmented worms (class Polychaeta) . (See Sludgeworms) BLOOM A readily visible concentrated growth or aggregation of minute organisms, usually algae, in bodies of water. BRACKISH WATERS Those areas where there is a mixture of fresh and salt water; or, the salt content is greater than fresh water but less than sea water; or, the salt content is greater than in sea water. o/ CARNIVOROUS Pertaining to animals that feed on other animals. (See Herbivorous) CARRYING CAPACITY The maximum quantity of organisms that any particular habitat can support over an extended period. CATABOLISM The breakdown of organic compounds within an organism. (See Metabolism) CATADROMOUS Pertaining to fish that spend most of their life in freshwaters; but migrate to the sea to spawn; e.g., american eel. (See Anadromous) CATASTROPHIC DRIFT Massive drift of bottom organisms under conditions of stress such as floods or toxicity. (See Drift Organisms. Incidental Drift, Periodic Drift) CHEMICAL STRATIFICATION A layering of water in a lake because of density differences owing to the varying or differential concentrations of dissolved substances with depth. (See Stratification) CHLOROPHYLL Green photosynthetic pigment present in many plant and some bacterial cells. There are seven known types of chlorophyll; their presence and abundance vary from one group of photosyn- thetic organisms to another. C-2 CHRONIC TOXICITY Toxicity, marked by a long duration, that produces an adverse effect on organisms. The end result of chronic toxicity can be death although the usual effects are sublethal; e.g., inhibits reproduction, reduces growth, etc. These effects are reflected by changes in the productivity and population structure of the community. (See Acute Toxicity) CLASSIFICATION The placing of organisms into groups (or categories) according to established scientific requirements. (See Taxonomy) CLEAN WATER ASSOCIATION An association of organisms found in any natural, unpolluted environment . These associations are characterized by the presence of species that are sensitive to environmental changes caused by Introduction of pollutants. In many cases the presence of a wide variety of species with relatively few individuals representing any one of them is also a characteristic. (See Sensitive Organisms, Tolerant Association) COASTAL PLAIN A plain between the sea and higher land, usually at a low elevation. COASTAL WATERS Those waters surrounding the continent which exert a measurable influence on uses of the land and on its ecology. The Great Lakes and the waters to the edge of the continental shelf. C-3 COASTAL ZONE Coastal waters and adjacent lands which exert a measurable influence on the uses of the sea and its ecology. The zone extends onshore to the upper reaches of the tidal zone and adjacent shore areas. (See Estuary) COLD-BLOODED ANIMALS Animals that lack an internal temperature regulating mechanism to offset external temperature changes. Their body temperature fluctuates to a large degree with that of their environment. Examples are fish and aquatic invertebrates . COLONY A distinguishable localized population within a species. COMMUNITY An aggregation of organisms within a specified area; all forms of life inhabiting a common environment. COMPENSATION LEVEL The depth of a waterway at which there is a balance between photosynthesis and respiration. COMPETITION The effort of two or more individuals or species of a community to utilize some of the same environmental resources. COMPETITION No two species can occupy the same niche at EXCLUSION PRINCIPLE (Gause's Rule) the same time. C-4 CONSUMERS Heterotrophic organisms, chiefly animals, that ingest other organisms or particle organic matter. Often divided into primary consumers (Herbivores) , secondary consumers (Carnivores which eat primary consumers), etc. (See Heterotrophic, Trophic Level) CONTINENTAL SHELF The shallow, gently sloping portion of the seabottom bordering a continent, down to a depth of about 200 meters. CONTINENTAL SLOPE The steeply sloping portion of the seabottom extending seaward from the continental shelf. CORAL A marine member of the phylum Coelenterata which secretes a hard exoskeleton, chiefly of calcium carbonate. CORAL REEF Large coral mass associated with coastal areas in the tropics (See Barrier Reef, Fringing Reef, Atoll) CRITERIA (Water Quality Criteria) CRITICAL LEVEL (Threshold) CRITICAL RANGE In bioassays , the range of magnitude of any factor between the maximum level or concentration at which no organisms die to the minimum level or concentration at which all organisms die under a given set of conditions in a given period of time. C-5 CULTURAL Acceleration by man of the natural process of EUTROPHICATION enrichment (aging) of bodies of water. CULTURE Cultivation of organisms in a medium containing necessary nutrients. D-/ DECOMPOSERS (Reducers) DELTA (Alluvial Fan) A fan-shaped deposition of silt, sand, gravel or other fine materials from a stream. These occur when the hydraulic gradient lessens abruptly, as in the discharge of a stream into a lake, or a river into an ocean. (See Alluvial) DENSITY (Population Species) The number of individuals in relation to the space in which they occur; refers to the closeness of individuals to one another at a given time. DENSITY STRATIFICATION (Stratification) DEPOSITING SUBSTRATES Bottom areas where solids are being actively deposited because of slackening movement of the transporting agent. These often occur in the vicinity of effluent discharges. (See Sludge Deposits) DETRITUS Fragments of detached or broken down material. DIRECT TOXICITY Toxicity that has an effect on organisms themselves instead of having an effect by alteration of their habitat or interference with their food supply. (See Acute Toxicity, Chronic Toxicity, Indirect Toxicity) D-2 DIURNAL 1. Refers to an event, process, or specific change that occurs every day; usually associated with changes from day to night. 2. Pertaining to those organisms that are active during day time. (See Nocturnal) DIVERSITY Pertaining to the variety of species within a given association of organisms. Areas of high diversity are characterized by a great variety of species; usually relatively few individuals represent any one species . Areas with low diversity are characterized by a few species; often relatively large numbers of individuals represent each species. DOMINANT SPECIES Species of a community which by their activity, behavior, or number, have considerable influence or control upon the conditions of existence of associated species; species which "controls" its habitat and food web. (See Predominant) DRIFT ORGANISMS Benthic organisms temporarily suspended in the water and carried downstream by the current. (See Incidental Drift, Periodic Drift, Catastrophic Drift) l>-3 DYSTROPHIC LAKES Shallow lakes with hrown water, high humic material and organic matter content, low nutrient availability, poor bottom fauna, and high oxygen demand; oxygen is continually depleted and pH is usually low. In lake aging the "age" between a eutrophic lake and a swamp. EBB TIDE E-/ That period of tide between a high water and the succeeding low water; falling tide. (See Flood Tide) EC50 Concentration of a substance producing 50% decrease in shell growth. ECOLOGICAL FACTOR Any part or condition of the environment that influences the life of one or more organisms. (See Biotic Factor) ECOLOGICAL NICHE The role of an organism in an ecosystem, its activities and relationships to the living and nonliving environment; food and nutrition relationships are of primary importance. (See Habitat Niche) ECOLOGY Interrelationships between organisms and their environment . ECOSYSTEM A community, including all the component organisms, together with the environment , forming an interacting system. ECOTYPE (Habitat Form) A locally adapted population of a species which has a distinctive limit of tolerance to envi- ronmental factors. (Individuals of the same species may appear different in various habitats) . E-2 EMERSED (Emergent) AQUATIC PLANTS Plants that are rooted at the bottom of a body of water, but project above the surface; e.g., cattails, bulrushes, etc. (See Floating Aquatic Plants , Submersed Aquatic Plants) ENRICHMENT An increase in the quantity of nutrients available to aquatic organisms for their growth. (See Eutrophication) ENRICHMENT FACTOR Number of times a substance is concentrated in the tissue of an organism over the concentration in its environment. (See Biological Magnification) ENVIRONMENT All external influences and conditions affecting the life and development of an organism or community. ENVIRONMENTAL RESISTANCE Restriction imposed on the numerical increase of a population by environmental factors. (See Biotic Potential) EPILIMNION The water mass extending from the surface to the thermocline in a stratified body of water; the epilimnion is less dense than the lower waters and is wind-circulated and essentially homothermous. (See Hypolimnion) EQUILIBRIUM The condition in which a population or community is maintained with only minor fluctuations in composition over an extended period of time. E-3 ESTUARY That portion of a coastal stream influenced by the tide of the body of water into which it flows; a bay, at the mouth of a river, where the tide meets the river current; an area where fresh and marine waters mix. (See Positive Estuary, Inverse Estuary, Neutral Estuary, Coastal Zone) EULITTORAL ZONE (Tidal Zone) EUPHOTIC ZONE The lighted region of a body of water that extends vertically from the water surface to the depth at which photosynthesis fails to occur because of insufficient light penetration. EURY- Prefix meaning wide; e.g., euryhaline refers to a wide range of salienty tolerance; eurythermal refers to a wide range of temperature tolerance. (See Steno-) EUTROPHIC LAKES Lakes which are rich in nutrients and organic materials, therefore, highly productive. These lakes are often shallow and seasonally deficient of oxygen in the hypolimnion. (See Oligotrophic Lakes) E-4 EUTROPHI CATION The natural process of the maturing (aging) of a lake; the process of enrichment with nutrients, especially nitrogen and phosphorus, leading to increased production of organic matter. (See Cultural Eutrophication, Oligotrophia: Lakes, Eutrophic Lakes) F-/ FALCULTATIVE Refers to the capability of an organism to live under varying conditions; e.g., a f alcultative anaerobe is an organism that although usually living in the presence of free oxygen can live in the absence of free oxygen. (See Obligate) FALL OVERTURN A physical phenomenon that may take place in a body of water during early autumn. The sequence of events leading to fall overturn include: (1) cooling of surface waters, (2) density change in surface waters producing convection currents from top to bottom, (3) circulation of the total water volume by wind action, and (4) vertical temperature equality. The overturn results in a uniformity of the physical and chemical properties of the entire water mass. (See Spring Overturn) FATHOM A unit of measurement equal to 6 feet (1.83 meters) . FAUNA Animal life . FIRTH A narrow arm of the sea; also the opening of a river into the sea. (See Estuary) FJORD (Fiord) A narrow arm of the sea between highlands . (See Firth. Estuary) F-2 FLOATING AQUATIC PLANTS Rooted plants that wholly or In part float on the surface of the water; e.g., water lilies, water hyacinth and duckweek. (See Emersed Aquatic Plants, Submersed Aquatic Plants) FLOOD TIDE That period of tide between low water and the succeeding high water; a rising tide. (See Ebb Tide) FLORA Plant life. FLUVIAL Of or pertaining to rivers; growing or living in streams; produced by river action, as a fluvial plain. FOOD CHAIN Dependence of a series of organisms, one upon the other, for food. The chain begins with plants and ends with the largest carnivores; e.g. , phytoplankton ■»■ zooplankton ■* forage fish -*■ game fish. FOOD CYCLE (Food Web) All the interconnecting food chains In a community. FORAGE FISH Fish, usually smaller prolific species, that are important as food for predatory species. FREE-SWIMMING (Motile) Actively moving about in water or capable of moving about in water. (See Sessile) F-3 FRINGING REEF Large coral mass at the edge of any land mass In tropical seas; It begins at the water's edge and may extend out to a quarter mile. (See Barrier Reef, Atoll) G-/ GAME FISH (Sport Fish) Those species of fish considered to possess sporting qualities on fishing tackle; e.g., salmon, trout, black bass, striped bass, etc. Game fish are usually considered to be more sensitive to environmental changes than rough fish. CAUSE'S RULE (Competition-Exclusion Principle) H- / HABITAT (Biotope) A specific type of place that is occupied by an organism, a population, or a community. HABITAT FORM (Ecotype) HABITAT NICHE The specific part or smallest unit of a habitat occupied by an organism. (See Ecological Niche) HADAL ZONE Pertaining to that part of the ocean at depths exceeding 6000 meters, including both water and floor or bottom. (See Abyssal Zone) HERBICIDE A chemical substance used for killing plants, especially weeds. HERBIVORE An organism that feeds on plant material, (See Carnivore) HETEROGENEOUS Consisting of dissimilar elements or constituents, (See Homogeneous) HETEROTROPHIC (Holozoic) Pertaining to organisms that are dependent on organic material for food. (See Autotrophic) HIGHER AQUATIC PLANTS (Pond Weeds, Aquatic Vascular Plants) Those plants composed of complex and differentiated tissues whose seeds germinate in the water phase or substrate of a body of water and which must spend part of their life cycle in water. This grouping includes plants which grow completely submersed as well as a variety of emersed and floating leaf types. (See Macrophyte) H-2 HOLOPHYTIC HOLOZOIC HOMOGENEOUS HOMOTHERMOUS HYPOLIMNION (Autotrophic) (Heterotrophic) Of uniform composition throughout. Having the same temperature throughout. The region of a body of water that extends from the thermocline to the bottom and is essentially removed from major surface influences. (See Epilimnion) IDENTIFICATION I- / The use of a taxonomic key or the equivalent to determine the scientific name of an organism. INCIDENTAL DRIFT The casual, random drift of organisms. (See Drift Organisms, Catastrophic Drift, Periodic Drift) INCIPIENT LETHAL LEVEL (ILL) That concentration of an environmental identity beyond which an organism could no longer survive for an indefinite period of time. INDICATOR ORGANISMS A species, whose presence or absence may be characteristic of environmental conditions in a particular area or habitat; however, species composition and relative abundance of individual components of the population or community are usually considered to be a more realiable index of water quality. INDIGENOUS Refers to an organism that is native, not introduced in an area. INDIRECT TOXICITY INLET Toxicity that affects organisms by interfering with their food supply or modifying their habitat instead of directly acting on the organisms themselves. (See Direct Toxicity) A short, narrow waterway connecting a bay, lagoon, or similar body of water with a large parent body of water; an arm of the sea, or other body of water, that is long compared to its width, and that may extend a considerable distance inland. 1-2 INSTAR A stage in the life cycle of an insect or other arthropod between two successive molts . INTERACTION Mutual or reciprocal action or influence between organisms, between organisms and environment , or between environmental factors. INTERSPECIFIC Refers to relations or conditions between species. (See Intraspecific) INTERTIDAL ZONE (Tidal Zone) INTOLERANT ORGANISMS (Sensitive Organisms) INTRASPECIFIC Refers to relations or conditions between individuals within a species. (See Interspecific) INVERSE ESTUARY Type of est ary in which evaporation exceeds the supply of freshwater; evaporation > freshwater inflow + precipitation. (See Positive Estuary, Neutral Estuary) INVERTEBRATES Animals without an internal skeletal structure; e.g., insects, mollusks, crayfish. (See Veterbrate) LAGOON w 1. A shallow sound, pond, or channel near or communicating with a larger body of water. 2. A settling pond for treatment of wastewater. LARVA The immature form of an animal which is unlike its parents. Larva are usually self-feeding but must pass through some sort of metamorphosis before assuming the characteristics of the adult; in insects, the wormlike stage between the egg and the pupa. LAW OF THE MINIMUM, LIEBIG'S "The growth and reproduction of an organism is dependent on the nutrient substance, such as oxygen, carbon dioxide, calcium, etc., that is available in minimum quantity." (See Limiting Factor) LAW OF TOLERANCE, SHELFORD ' S "When one environmental factor or condition is near the limits of toleration, either minimum or maximum, that one factor or condition will be the controlling one and will determine whether or not a species will be able to maintain itself." (See Limiting Factor) LENTIC Pertaining to standing (nonflowing) waters such as lakes, ponds, and swamps. (See Lotic) LIFE CYCLE The various phases, changes, or stages through which an individual passes from the fertilized egg to death of the mature organism. (See Metamorphosis) L-2 LIMITING FACTOR A factor whose absence, or excessive concentration, exerts some restraining influence upon a population through incompatibility with species requirements or tolerance. (See Law of the Minimum , Law of Tolerance) LIMNETIC ZONE The open -water region of a lake, especially in areas too deep to support rooted aquatic plants. This region supports plankton and fish as the principal plants and animals . (See Littoral Zone) LIMNOLOGY The ecology of fresh waters . LITTORAL ZONE The shallow area that extends from shore to the lakeward limit of rooted aquatic plants; the shoreward region of a body of water; in marine ecology, the tidal zone. (See Limnetic Zone) LOTIC Pertaining to flowing waters such as streams and rivers. (See Lentic) M-/ MACROORGANISMS Those organisms visible to the unaided eye (Macroinvertebrates) ^ wh±ch ^ retained on a u. S. standard sieve no. 30 (openings of 0.589 mm.). (See Microorganisms) MACROPHYTE Any plant that can be seen with the naked, unaided eye; e.g., aquatic mosses, ferns, liverworts, rooted plants, etc. MARL An earthy, unconsolidated deposit formed in freshwater lakes, chiefly of calcium carbonate mixed with clay or other impurities in varying proportions. MARSH Periodically wet or continually flooded area with the surface not deeply submerged. Covered dominantly with emersed aquatic plants; e.g., sedges, cattails, rushes. MEDIAN TOLERANCE LIMIT (TLm) The concentration of tested substance in water at which just 50% of the test organisms survive for a specified period of exposure. (See Tolerance Limit) MEROMICTIC LAKES Lakes in which dissolved substances create a gradient of density differences with depth; this prevents complete mixing or circulation of water masses. (See Chemical Stratification) M-2 MEROMIXIS A condition of permanent stratification of water masses in lakes. MESOLIMNION (Thermocline) METABOLISM The sum of all chemical processes occurring within an organism; includes both synthesis (anabolism) and breakdown (catabolism) of organic compounds. METALIMNION (Thermocline) METAMORPHOSIS Abrupt transformation of an animal from one distinctive life history stage to another in its postembryonic development; e.g., larva of an insect to a pupa. (See Life Cycle) MICROORGANISMS Those minute organisms invisible or only barely (Microinvertebrates) . .., , ,, . visible to the unaided eye. Microorganisms pass through a U. S. standard series no. 30 sieve but are retained on a no. 100 sieve (openings of 0.149 mm). (See Macroorganisms) MOLT To cast or shed periodically the outer body covering which permits an increase in size. This is especially characteristic of inverte- brates. (See Ins tar) MOTILE ( Free-Swimming) NANOPLANKTON N-/ Very minute p lankton not retained in a plankton net equipped with no. 25 silk bolting cloth (mesh, 0.03 to 0.04 mm.). NATIVE SPECIES A species that is part of an area's original biota. NATURAL SELECTION Processes occurring in nature which result in survival of the fittest and elimination of individuals less well adapted to their environment. NAUPLIUS Free-swimming microscopic larval stage characteristic of many crustaceans, barnacles, etc. NEAP TIDES Exceptionally low tides which occur twice each month when the earth, sun and moon are at right angles to each other; these usually occur during the moon's first and third quarters. (See Spring Tides) NEKTON Macroscopic organisms swimming actively in water; e.g., fish. (See Plankton) NERITIC ZONE Relatively shallow water zone which extends from the high-tide mark to the edge of the continental shelf. NET PLANKTON Plankton retained in a plankton net equipped with no. 25 silk bolting cloth (mesh, 0.03 to 0.04 mm. ) . N-2 NEUSTON Organisms associated with, or dependent upon, the surface film (air-water interface) of bodies of water. NEUTRAL ESTUARY Type of estuary in which neither the freshwater inflow nor the evaporation predominates; freshwater inflow + precipitation - evaporation. (See Positive Estuary, Inverse Estuary) NICHE (See Ecological Niche. Habitat Niche) NOCTURNAL Pertaining to those organisms that are active at night. (See Diurnal) NUISANCE ORGANISMS (Pests) Those organisms capable of interfering with the use or treatment of water. NUTRIENTS Elements, or compounds, essential as raw materials for organism growth and development; e.g., carbon, oxygen, nitrogen, phosphorus, etc. NYMPH An immature developmental form characteristic of the pre-adult stage in insects that do not have a pupal stage; e.g., mayflies and stoneflies. (See Larva) evaporation. (See Inverse Estuary, Neutral Estuary) POTAMON ZONE Stream reach at lower elevations characterized by reduced flow, higher temperature, and lower dissolved oxygen levels . (See Rithron Zone) P-3 PREDATOR An animal that kills and consumes other animals. (See Prey) PREDOMINANT Those organisms that are of outstanding abundance in a particular community for a given period of time. (See Dominant) PREY An animal that is killed and consumed by another animal. (See Predator) PRIMARY PRODUCTIVITY The total quantity of protoplasm produced by autotrophic organisms per unit of time in a specified habitat. PRODUCERS Organisms that synthesize organic material from inorganic substances; e.g., plants. (See Consumers, Reducers) PRODUCTION The process of producing organic material; the quantity produced. PRODUCTIVITY 1. Rate of protoplasm formation or energy utilization by one or more organisms; total quantity of organic material produced within a given period in a specified habitat. 2. Capacity or ability of an environmental unit to produce organic material. (See Primary Productivity, Secondary Productivity) P-4 PROFUNDAL ZONE The deep, bottom-water area beyond the depth of effective light penetration. All of the lake floor beneath the hypolimnion. PROLIFIC Pertaining to organisms that have a high reproduction rate and normally produce large numbers of young. PROTOPLASM The living material in cells of plants and animals . PUPA An intermediate, usually quiescent, form following the larval stage in insects, and maintained until metamorphosis to the adult stage. (See Larva) Q-/ QUALITY A term to describe the composite chemical, physical, and biological characteristics of a water with respect to its suitability for a particular use. QUIESCENT Refers to the temporary cessation of development. movement or other activity. (See Puoa) R-/ RAPIDS Areas of a stream where velocity of current is great enough to keep the bottom clear of all loose materials, thus providing a firm substrate. The surface of the water is disrupted by turbulent currents. This area is occupied largely by specialized benthic or periphytic organisms that can firmly attach or cling to a firm substrate. (See Pools, Riffles) RED TIDE A visible red-to-orange coloration of an area of the sea caused by the presence of a bloom of certain plankton. These blooms are often the cause of major fish kills. REDD A type of fish spawning area associated with flowing water and clean gravel. Fishes that utilize this type of spawning area include trout, salmon, some minnows, etc. REDUCERS (Decomposers) Those organisms, usually bacteria or fungi, that break down complex organic material into simpler compounds. (See Producers, Consumers) REEF A ridge of rocks, sand, soil or coral projecting from the bottom to or near the surface of the wat er . RESPIRATION The complex series of chemical and physical reactions in all living organisms by which the energy and nutrients in foods is made available for use. Oxygen is used and carbon dioxide released during this process. (See Metabolism) R-2 RIFFLES A shallow rapids in an open stream where the water surface is broken into waves by wholly or partly submerged obstructions. Riffles usually support a wider variety of bottom organisms than other stream sections. (See Pools) RITHRON ZONE Stream reach at higher elevations characterized by rapid flow, low temperature, and high dissolved oxygen levels. (See Potamon Zone) ROUGH FISH Those species of fish considered to be of poor fighting quality when taken on tackle; e.g., carp, gar, suckers, etc. These fish are considered undesirable in most situations, Most species in the group are more tolerant of widely changing environmental conditions than game fish. s-/ SALT MARSH Low area adjacent to the sea that is covered with salt tolerant vegetation and regularly flooded by high tide; similar inland areas near saline springs or lakes , though not regularly flooded. SAPROBIC Living on dead or decaying organic matter. (See Scavenger) SAPROBICITY The sum of all metabolic processes which are the direct opposite of primary production; can be measured either by the dynamics of metabolism or analysis of community structure. SAPROBIENSYSTEM European system of classifying organisms according to their response to organic pollution in slow moving streams. 1. Alpha-Mesosaprobic Zone - Area of active decomposition, partly aerobic, partly anaerobic, in a stream heavily polluted with organic wastes. 2. Beta-Mesosaprobic Zone - That reach of a stream that is moderately polluted with organic wastes. 3. Oligosaprobic Zone - That reach of a stream that is slightly polluted with organic wastes and contains the mineralized products of self-purification from organic pollution, but with none of the organic pollution remaining. S-2 4. Polysaproblc Zone - That area of a grossly polluted stream which contains the complex organic wastes that are decomposing primarily by anaerobic processes. SCAVENGER An organism that consumes decomposing organic matter. SECONDARY PRODUCTIVITY Total quantity of animal (and other heterotrophic) protoplasm produced per unit of time in a specified habitat. (See Primary Productivity, Productivity) SEICHE Periodic oscillations in the water level of a lake or other landlocked body of water due to unequal atmospheric pressure, wind, or other cause, which sets the surface in motion. These oscillations take place when a temporary local depression or elevation of the water level occurs. SENSITIVE ORGANISMS (Intolerant Organisms) Organisms that exhibit a rapid response to environmental changes and are killed, driven out of the area, or as a group are substantially reduced in numbers when their environment is fouled. (See Tolerant Association) SESSILE Pertaining to those organisms that are attached to a substrate and not free to move about; e.g., periphyton. (See Free- Swimming) S-3 SESTON All material, both organic and inorganic, suspended in a waterway. Bioseston is the living material; abioseston is the non-living portion. SLUDGE DEPOSITS Accumulations of settled, usually rapidly decomposing, organic material in the aquatic system. A deposit of solids of wastewater origin. SLIMES Substances of viscous organic nature, usually formed from microbiological growth. SLUDGEWORMS Aquatic segmented worms (class - Oligochaeta) that exhibit marked population increases in waters polluted with decomposable organic wastes. (See Bloodworms) SPAWN 1. In aquatic animals, to produce or deposit eggs or sperm. 2. To produce eggs or young. 3. Eggs of fishes and higher aquatic invertebrates. SPECIES (Both singular and plural) An organism or organisms forming a natural population, or groups of populations , that transmit specific characteristics from parent to offspring. Each species is reproductively isolated from other populations with which they might breed. Hybrids, the results of interbreeding, usually exhibit a loss of fertility. S-4 SPORT FISH (Game Fish) SPRING OVERTURN A physical phenomenon that may take place in a body of water during the early spring. The sequence of events leading to spring overturn include: (1) melting of ice cover, (2) warming of surface waters, (3) density changes in surface waters producing convection currents from top to bottom, (A) circulation of the total water volume by wind action, and (5) vertical temperature equality. The overturn results in a uniformity of the physical and chemical properties of the entire water mass. (See Fall Overturn, Overturn) SPRING TIDE Exceptionally high tide which occurs twice per lunar month when there is a new or full moon, and the earth, sun, and moon are in a straight line. (See Neap Tides) STANDARD STANDING CROP STENO- (Water Quality Standard) The quantity of living organisms present in an environment at a selected point in time. Prefix denoting a narrow range of tolerance of an organism to a specific environmental factor; e.g., stenothermal refers to temperature; stenohaline refers to salienity; etc. (See Eury-) STIMULUS An influence that causes a response in an organism. (See Taxis) S-5 STRATIFICATION (Density Stratification) Arrangement of water masses into separate, distinct, horizontal layers as a result of differences in density; may be caused by differences in temperature, dissolved or suspended solids. (See Thermal Stratification, Chemical Stratification) STRESS The conditions resulting from any environmental change that disturbs the normal functioning of an animal to such an extent that its chances for survival are reduced. SUBLITTORAL ZONE The part of the shore from the lowest water level to the lower boundary of plant growth; transition zone from the littoral to profundal bottom. SUBMERSED (Submerged) AQUATIC PLANTS Higher aquatic plants that grow, or are adapted to grow, beneath the surface of the water; e.g., pondweed, coontail, etc. SUBSTRATE The bottom material of a waterway; the base or substance upon which an organism is growing; a substance undergoing oxidation. SUMMER KILL Complete or partial kill of a fish population in ponds or lakes during the warm months; variously produced by excessively warm water, by a depletion of dissolved oxygen, and by the release of toxic substances from a decaying algal bloom, or by a combination of these factors. (See Winter Kill) S-6 SUPRALITTORAL ZONE (Supratidal Zone) The portion of the seashore adjacent to the tidal or spray zone. SURFACE AQUATIC PLANTS (Floating Aquatic Plants) SYMBIOSIS Two organisms of different species living in close association, one or both of which may benefit and neither is harmed. Such a phenomenon is found among organisms in biological treatment processes. SYNERGISM The joint action of two or more substances is greater than the sum of the action of each of the individual substances; e.g., action of certain combinations of toxicants. The improvement in performance achieved because two agents are working together. (See Antagonism) SYNTHESIS The production of a substance by the union of elements or simpler chemical compounds. SYSTEMATICS (Taxonomy) T-/ TAXIS Directed movement by an organism in response to a stimulus; e.g., photo taxis is directed movement in response to a light stimulus; thermo taxis is directed movement in response to heat or cold as a stimulus; etc. TAXON (Taxa) A "kind" of organism. - Any taxonomic unit or category of organisms; e.g., species, genus, family, order, etc. TAXONOMY (Systematics) Organism classification with reference to their precise relationship in the plant or animal kingdom; includes the bases, principles, procedures and rules of classification. TERRESTRIAL Growing, living, or peculair to the land, as opposed to the aquatic environment. TERRITORY The area which an animal defends against intruders. THERMAL STRATIFICATION The layering of water masses owing to different densities in response to temperature. The condition of a body of water in which the successive horizontal layers have different temperatures , each layer more or less sharply differentiated from the adjacent ones, the warmest (or the coldest) at the top. (See Overturn) T-2 THERMOCLINE (Mesolimnion, Metalimnion) The transition zone between the warm epilimnion and cold hypolimnion of stratified bodies of water; temperature change equals or exceeds 1°C for each meter of depth. (See Thermal Stratification) THRESHOLD (Critical Level) The maximum or minimum duration or intensity of a stimulus that is required to produce a response in an organism. TIDAL FLAT The sea bottom, usually wide, flat, muddy and nonproductive, which is exposed at low tide. A marshy or muddy area that is covered and uncovered by the rise and fall of the tide. TIDAL MARSH A low, flat marshland that is traversed by interlacing channels and tidal sloughs; periodically inundated by high tides; vegetation consists of rushes, grasses, and other salt tolerant plants. TIDAL ZONE (Eulittoral Zone, Intertidal Zone) The area of a shore between the limits of water level fluctuation; the area between the levels of high and low tides. TIDE The alternate rising and falling of water levels, twice in each lunar day, due to gravitational attraction of the moon and sun in conjunction with the earth's rotational force. TL* (TL50) (Median Tolerance Limit) T-3 TOLERANCE Relative capability of an organism to endure or adapt to an unfavorable environmental factor. TOLERANCE LIMIT (TL10...100) The concentration of a substance which some specified portion of an experimental population can endure for a specified period of time with reference to a specified type of response; e.g., TL100 means tnat all test organisms endured the stress for the specified time; TLiq means only 10% of the test organisms could tolerate the imposed stress for the specified time. (See Median Tolerance Limit) TOLERANCE RANGE TOLERANT ASSOCIATION The range of one or more environmental conditions within which an organism can function; range between the highest and lowest value of a particular environmental factor in which an organism can live. An association of organisms capable of withstanding adverse conditions within the habitat. This association is often characterized by a reduction in the number of species (from a clean water association) and, in the case of organic pollution, an increase in individuals representing certain species. TOXICANT A substance that through its chemical or physical action kills, injures, or impairs an organism; any environmental factor which, when altered, produces a harmful biological effect. (See Pesticide) T-4 TOXICITY Quality, state or degree of the harmful effect resulting from alteration of an environmental factor. TRIPTON The dead suspended particulate matter in aquatic habitats; the nonliving portion of the Seston. TROPHIC LEVEL One of the parts in a nutritive series in an ecosystem in which a group of organisms in a certain stage in the food chain secures food in the same general manner. The first or lowest trophic level consists of producers (green plants) ; the second level of herbivores ; the third level of secondary carnivores . Most bacteria and fungi are organisms in the reducer (decomposer) trophic level. TROPHOGENIC REGION The area of a body of water where organic production from mineral substances takes place on the basis of light energy and photosynthetic activity. TROPHOLYTIC REGION The deep area of a body of water where organic breakdown predominates because of light deficiency. TURNOVER (Overturn) u-/ UBIQUITOUS ORGANISMS Organisms that can tolerate a wide range of environmental conditions or variation; organisms that are so active or numerous as to seem to be present or existent in all types of environments. (See Tolerant Association. Sensitive Organisms) UNICELLULAR Refers to an organism that consists of only one cell; e.g., blue green algae, protozoa, bacteria. These organisms may, however, be filamentous or colonial in form. V- / VERTEBRATES Animals that have an internal skeletal system. (See Invertebrate) w-/ WATER POLLUTION Alteration of the aquatic environment in such a way as to interfere with a designated beneficial use. WATER QUALITY CRITERIA "A scientific requirement on which a decision or judgement may be based concerning the suitability of water quality to support a designated use." (See Water Quality Standard) WATER QUALITY STANDARD "A plan that is established by governmental authority as a program for water pollution prevention and abatement." (See Water Quality Criteria) WINTER KILL The death of fishes in a body of water during a prolonged period of ice and snow cover; caused by oxygen exhaustion due to respiration and lack of photosynthesis. (See Summer Kill) z-/ ZONE An area characterized by similar flora or fauna; a belt or area to which certain species are limited. ZOOPLANKTON The animals of the plankton. Unattached microscopic animals having minimal capability for locomotion. SELECTED REFERENCES ^ ^ Anon. Glossary - Water and Wastewater Control Engineering. Prepared by Joint Editorial Board Representing APHA, ASCE, AWWA, WPCS. 1969. Anon. Report of The Committee on Water Quality Criteria. USDI, FWPCA. 1968. Anon. Resource Conservation Glossary. Soil Conservation Society of America. Ankeny, Iowa. 1970. Edmonson, W. T. (Editor). Ward and Whipple's Freshwater Biology. Second Edition. John Wiley & Sons, Inc. New York. 1959. Geckler, J. R. , K. M. Mackenthun and W. M. Ingram. Glossary of Commonly Used Biological and Related Terms in Water and Waste Water Control. USDHEW, PHS No. 999-WP-2. 1963. Hanson, H. C. Dictionary of Ecology. Philosophical Library. New York. 1957. Ingram, W. M. , K. M. Mackenthun and A. F. Bartsch. Biological Field Investigative Data for Water Pollution Surveys. USDI, FWPCA, WP-13. Pages 17-46. 1966. Kenneth, J. H. (Editor). A Dictionary of Biological Terms. Eighth Edition. D. Van Nostrand Company, Inc. New York. 1963. Ludzack, F. J. Glossary of Wastewater and Surface Water Technology. Reference Outline Series. USDI, FWPCA, National Training Center, Cincinnati. 1968. Needham, J. G. and P. R. Needham. A Guide to the Study of Freshwater Biology. Fifth Edition. Holden-Day, Inc. San Francisco. 1962. Odum, E. P. Fundamentals of Ecology. W. B. Saunders Company. Philadelphia. 1959. Pennack, R. W. Collegiate Dictionary of Zoology. The Ronald Press Co. New York. 1964. Pennack, R. W. Fresh-Water Invertebrates of the United States. The Ronald Press Co. New York. 1953. z-3 Rechard, P. A. and R. McQuisten. Glossary of Selected Hydrologlc Terms. Water Resources Research Institute, University of Wyoming, Laramie. Water Resources Series No. 1. 1966 (Revised 1968) . Reid, G. K. Ecology of Inland Waters and Estuaries. Reinhold Publishing Corporation. New York. 1961. Ruttner, F. Fundamentals of Limnology. University of Toronto Press. Third Edition. Toronto, Ontario. 1963. Stewart, K. M. and G. A. Rohlich. Eutrophication - A Review. A Report to the State Water Quality Control Board, California. Publication No. 34. Sacramento. 1967. Storer, T. I. and R. L. Usinger. General Zoology. McGraw-Hill Book Co., Inc. New York. 1957. Sverdrup, H. U. , M. W. Johnson and R. H. Fleming. The Oceans, Their Physics, Chemistry, and General Biology. Prentice Hall, Inc. New York. 1942. Welch, P. S. Limnology. Second Edition. McGraw-Hill Book Co. New York. 1952. * US.eOVH»«(0«TI>l