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Vocabulary for Stream & Aquatic Environments |
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| Abiotic |
pertaining to the non-living components of the environment, including soil, water, air, light, nutrients, and the like. |
| Adaptation |
a genetically determined characteristic (behavioral, morphological, and physiological) that improves an organism's ability to survive and reproduce under prevailing environmental conditions. |
| Available water capacity |
supply of water available to plants in well-drained soil. |
| Basin |
a depression in land often containing a lake, pond, or river at its lowest point. |
| Benthic |
bottom dwelling or substrate-oriented; at or in the bottom of a stream or lake |
| Biochemical oxygen demand (BOD) |
a measure of the oxygen needed in a specified volume of water to decompose organic materials; the greater the amounts of organic matter in water the higher the BOD. |
| Biome |
major regional ecological community of plants and animals; usually corresponds to plant ecologist's and European ecologist's classification of plant formations and life zones. |
| Biosphere |
thin layer around Earth in which all living organisms exist. |
| Bog |
a wetland ecosystem characterized by an accumulation of peat, acid conditions, and dominance of sphagnum moss. |
| Buffer |
a chemical solution that resists or dampens change in pH upon addition of acids or bases. |
| Capillary water |
that portion of water in the soil held by capillary forces between soil articles. |
| Community |
a group of interacting plants and animals inhabiting a given area. |
| Competition |
any interaction that is mutually detrimental to both participants, within or between species that share limited resources. |
| Contaminants |
substances which are detrimental to water quality and aquatic life. |
| Diversity |
variation that occurs in plant and animal taxa (i.e., species composition), habitats, or ecosystems. |
| Diversity index |
the mathematical expression of species- richness of a given community or area. |
| Drainage basin |
land area where precipitation runs off into streams, rivers, lakes, and reservoirs. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge. Large drainage basins, like the area that drains into the Mississippi River, contain thousands of smaller drainage basins. Also called a "watershed." |
| Ecological restoration |
involves replacing lost or damaged biological elements (populations, species) and reestablishing ecological processes (dispersal, succession) at historical rates. |
| Ecosystem |
the biotic community and its abiotic environment functioning as a system. |
| Ecotone |
transition zone between two structurally different communities. |
| Ecotype |
a subspecies or race adapted to a particular set of environmental conditions. |
| Environment |
organism, including other plants and animals and total surroundings of an those of its own kind. |
| Estuary |
a partially enclosed embayment where fresh water and sea water meet; or mix, or where a river enters an ocean. |
| Erosion |
the process in which a material is worn away by a stream of liquid (water) or air, often due to the presence of abrasive particles in the stream. |
| Fecal coliform |
aerobic bacteria found in the colon or feces, often used as indicators of fecal contamination of water supplies. |
| Field capacity |
the amount of water held by soil against the force of gravity. |
| Floodplain |
a low area of land, surrounding streams or rivers, which holds the overflow of water during a flood. |
| Habitat |
where an organism lives or could live under specified environmental conditions |
| Hard water |
water with high concentrations of dissolved calcium and magnesium salts; generally found in areas of carbonate rocks such as limestone and dolomite. |
| Imperviousness |
the amount of hard, paved, and therefore impervious surfaces like rooftops, parking lots, and roads, present in the land draining to a stream. |
| Infiltration |
downward movement of water into the soil or subsurface. |
| Leaching |
the process by which rain water or irrigation water draws nutrients or toxic chemicals out of the soil, litter, and organic matter and carries them to nearby rivers or streams. |
| Lentic waters |
standing water, such as ponds or lakes. |
| Lotic waters |
flowing waters, as in streams and rivers |
| Macroinvertebrate |
aquatic organism without a backbone (invertebrate) that can be seen with the naked eye (macro); usually refers to aquatic insect larvae or nymphs. |
| Niche |
functional role of a species in the community, including activities and relationships. |
| Non-Point Source Pollution |
a type of pollution discharged over a wide land area, not from one specific location. These are forms of diffuse pollution caused by sedimenutrients, organic and toxic substances originating from land-use activities, which arent, carried to lakes and streams by surface runoff. Non-point source pollution is contamination that occurs when rainwater, snowmelt, or irrigation washes off plowed fields, city streets, or suburban backyards. As this runoff moves across the land surface, it picks up soil particles and pollutants, such as nutrients and pesticides. |
| Outfall |
the place where a sewer, drain, or stream discharges; the outlet or structure through which reclaimed water or treated effluent is finally discharged to a receiving water body. |
| Oxygen demand |
the need for molecular oxygen to meet the needs of biological and chemical processes in water. Even though very little oxygen will dissolve in water, it is extremely important in biological and chemical processes. |
| Peak flow |
the maximum instantaneous discharge of a stream or river at a given location. It usually occurs at or near the time of maximum stage. |
| pH |
a measure of the relative acidity or alkalinity of water. Water with a pH of 7 is neutral; lower pH levels indicate increasing acidity, while pH levels higher than 7 indicate increasingly basic solutions. |
| Point Source Pollution |
a type of pollution that can be tracked down to a specific source such as a factory discharge pipe. |
| Pollutant |
something that makes land, water, and/or air dirty and unhealthful. |
| Pollution |
the presence of waste that makes the world around us dirty and contaminated. |
| Recharge |
water added to an aquifer. For instance, rainfall that seeps into the ground. |
| Redds |
nests made in gravel (particularly by salmonids); consisting of a depression that is created and then covered. |
| Refugia |
stream areas that can provide shelter from predators or during adverse environmental conditions, e.g. pools that maintain cooler waters during warmer months of the year. |
| Richness |
the number of species present in an area, a component of species diversity. |
| Riffle |
a shallow area of a stream or river with a fast moving current bubbling over rocks. |
| Riparian |
type of wetland transition zone between aquatic habitats and upland areas. Typically, lush vegetation along a stream or river. |
| Riprap |
large rocks, broken concrete, or other structure used to stabilize streambanks and other slopes. |
| Runoff |
water, including rain and snow, which is not absorbed into the ground; instead it flows across the land and eventually runs into stream and rivers. Runoff can pick up pollutants from the air and land, carrying them into the stream. |
| Salmonid |
fish of the family Salmonidae, including salmon, trout, chars, whitefish, ciscoes, and grayling. |
| Scraper |
aquatic insect that feed by scraping algae from a substrate. |
| Sediment |
soil, sand, and materials washed from land into waterways. |
| Sedimentation |
when soil particles (sediment) settle to the bottom of a waterway. |
| Septic tank |
a tank used to detain domestic wastes to allow the settling of solids prior todistribution to a leach field for soil absorption. Septic tanks are used when a sewer line is not available to carry these wastes to a treatment plant. A settling tank in which settled sludge is in immediate contact with sewage flowing through the tank, and wherein solids are decomposed by anaerobic bacterial action. |
| Shredder |
a stream invertebrate that feeds on coarse particulate organic matter. |
| Soft water |
water with a low concentration of dissolved calcium and magnesium salts; tends to be acidic or circumneutral. |
| Stream |
a general term for a body of flowing water; natural water course containing water at least part of the year. In hydrology, it is generally applied to the water flowing in a natural channel as distinct from a canal. |
| Stream flow |
the water discharge that occurs in a natural channel. A more general term than runoff, streamflow may be applied to discharge whether or not it is affected by diversion or regulation. |
| Storm drain |
structure designed to carry runoff in a controlled fashion to management facilities or directly to streams. In Montgomery County, storm drains are strictly conveyances to streams, and no treatment for the runoff is contained within them. |
| Storm water |
runoff generated as a result of rain or snow. |
| Subwatershed |
refers to smaller drainage areas within the watershed of the County's major streams (e.g., Hawlings River within the Patuxent River Watershed) |
| Succession |
replacement of one community by another, often progressing to a stable terminal community called the climax. |
| Swamp |
a wooded wetland in which water is near or above ground level. |
| Thermal pollution |
a reduction in water quality caused by increasing water temperature, often due to disposal of waste heat from industryl, power generation processes, or urban impervious surfaces (such as parking lots). Thermally polluted water can harm the environment because plants and animals may have difficulty adapting to it. |
| Tributary |
a smaller river or stream that flows into a larger river or stream. Usually, a number of smaller tributaries merge to form a river. |
| Water cycle |
the circuit of water movement from the oceans to the atmosphere and to the Earth, and the return to the atmosphere through various stages or processes such as precipitation, interception, runoff, infiltration, percolation, storage, evaporation, and transpiration. |
| Water quality |
a term used to describe the chemical, physical, and biological characteristics of water, usually in respect to its suitability for a particular purpose. |
| Watershed |
the entire land area that drains water to a particular stream, river, or lake. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge. The topographic dividing line from which surface streams flow in two different directions. Large watersheds, like the Mississippi River or the Chesapeake Bay basin contain thousands of smaller watersheds. |
| Watershed restoration |
reestablishing the structure and function of an ecosystem, including its natural diversity; a comprehensive, long-term program to return watershed health, riparian ecosystems, and fish habitats to a close approximation of their condition prior to human disturbance |
| Watertable |
the upper level of groundwater. |
| Waterway |
a natural or man-made place for water to run through (such as river, stream, creek, or channel). |
| Wetland |
An area of land that is regularly wet or flooded, such as a marsh or swamp. |
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