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Ecological– Encompasses the habits of a species; the way a species relates to, or fits in with, its environment; where it lives, what it consumes, and how it avoids predators or displacement by other species.

Ecological Services– services provided to society by the ecosystem, such as storing and cycling essential nutrients, absorbing and detoxifying pollutants, maintaining the hydrological cycle, moderating the local climate; providing sites for recreation, tourism and inspiration.

Ecology– The relationship of living things to one another and their environment, or the study of such relationships.

Ecoregion– Large landscape areas defined by climate, physical characteristics of the landscape, and the plants and animals that are able to live there. Ecoregions contain many different physical settings and biological communities, which occur in predictable patterns.

Ecosystem– A natural system that includes the sum total of all living things, their physical environment and the interrelationships among them.

Ecotourism– Tourism involving travel to areas of natural or ecological interest for the purpose of observing wildlife and learning about the environment, e.g. bird watching.

Effluent– Wastewater discharged to a receiving body of water.

Emergent Marsh– Marshes in which vegetation is rooted underwater and the tops exposed (as contrasted with submerged vegetation or upland habitats).

Endangered Species– Animals, birds, fish, plants, or other living organisms threatened with extinction by anthropogenic (man-caused) or other natural changes in their environment. Requirements for declaring a species endangered are contained in the Endangered Species Act.

Estuary– A coastal,
semi-enclosed body of water where saltwater from the sea mixes with
freshwater from land drainage.

Estuarine Debris– Trash in a bay or along its shoreline; debris consists of tires, construction wastes, household trash, and plastic; debris degrades aesthetic values and represents a hazard to wildlife (e.g. entanglement or mistaken consumption as food).

Eutrophication– Nutrient over?enrichment of a water body resulting in overgrowth of algae, frequently followed by algae die?offs and oxygen depletion.

Exotic Species– Nonindigenous species of plants and animals (e.g. grass carp, chinese tallow tree) often established purposefully or inadvertently by human activity; some exotic species have fewer natural population controls in their new environment, becoming a pest or nuisance species.


Fecal Coliform Bacteria– Microorganisms that usually occur in the intestinal tract of “warm blooded” animals (including humans), e.g. Escherichia coli; commonly used as an indicator of contamination, (see also Most Probable Number.)

Finfish– Fish, as opposed to shellfish.

Food Chain– A series of interconnected feeding relationships; the process of energy capture (by green plants) and successive transfer to grazers (primary consumers) and predators (secondary consumers and above).

Food Web– The network of trophic relationships in an ecosystem; a complex network of food chain interactions.

Fresh Marsh– A type of wetland primarily found in areas of low salinity (< 0.5 ppt) that are affected by saltwater flooding only during large tropical storms or hurricanes. Plant species include Zizaniopsis miliacea (giant cut-grass), Sagittaria sp. (arrowhead), and Eleocharis quadrangulata (squarestem spikerush).

Freshwater Inflow– The flow of fresh water into the bay system from its watershed. The characteristic natural community living in and around Galveston Bay is largely defined by the volume, timing, location and quality of freshwater inflows.

Fringing Wetland– wetlands found at the periphery of the bay, typically brackish or salt marsh found along shorelines protected from strong wave action.


Geotextile Tube (Geotube)– Geotextile fabric bags filled in place hydraulically with sandy dredged material to form breakwaters. After placement, the tubes act as erosion protection structures for the dredged material, and for any intertidal wetlands that may develop.

Groundwater– Subsurface water, in the zone of saturation (below the water table); occurs in aquifers at one or more depth levels.

Guild– A group of species with similar ecological niches; the planktivorous fishes would constitute an estuarine species guild.


Habitat– The place in the environment where an organism lives or can be found.

Hydrologic Cycle– The continuous cycling of water in the biosphere as solid, liquid, and gas; water evaporates from oceans to the atmosphere and is returned to the ocean via precipitation and river flow.

Hydrology– The science dealing with the properties, distribution, and circulation of water.


Illicit Connection– a discharge to a storm sewer that is not composed entirely of storm water and is not authorized by a permit. Often caused by the unintentional discharge of domestic (human, household) wastewater via damaged wastewater collection systems, but also from intentional discharges of other wastes.

Impervious Cover– Land surfaces with a low capacity for soil infiltration, e.g. parking lots and roadways; degrades water quality by increasing surface runoff and the quantity of nonpoint source pollution.

Indicator Species– A species that, through its population size or condition, mirrors environmental conditions within an ecosystem.

Indigenous– Occurring naturally in a particular region or environment. Also referred to as the “native.”

Infauna– Animals living within sediments.

Inflow– The water feeding an estuary, generally referring to river sources.

Inter-Basin Transfer– The transfer of water from one river basin to another river basin for water supply purposes.

Intertidal– The portion of shoreline exposed at low tide and inundated by high tide.


Larval– the early life stage of an animal after hatching where its form is fundamentally unlike the mature form; the animal must metamorphose before assuming adult characters.

Loading– The rate of introduction of a constituent (e.g. contaminant) to a receiving water, for example in pounds per day. Loading is significant in relation to the volume and circulation of the receiving water; problems occur when high loadings occur into receiving waters with limited assimilative capacity.