Freshwater Ecology Final

Abiotic sulfur oxidation

reduced forms of sulfur combine with O₂ for a net release of potential energy spontaneously without biological mediation

Acute toxicity

poisoning with large pulses over short periods

Additive toxicity

when two toxicants together are more toxic than individually

Adhesion

sticking to other things

Advective transport

movement of materials by movement of parcels of water (as opposed to molecular diffusion)

Aerobic

oxic (with oxygen)

Akinete

resting cell of cyanobacteria and some green algae, generally resistant to poor growth conditions

Algae

nonvascular organisms capable of oxygenic photosynthesis without sterile cells covering gametangia

Alkalinity

the capacity of a solution to neutralize acid; the sum of all titratable bases; usually a function of carbonate, bicarbonate, and hydroxide contents

Allelochemical

a chemical produced by one species that alters behavior or growth of another species

Allen curve

a plot of individual size v.s. number of individuals in a cohort through time

Allochthonous

originating from outside the system; often refers to organic carbon

Alpha diversity

(α diversity), within-habitat diversity

Alternative stable states

the idea that ecosystems can exist under different biotic and abiotic conditions that persist in the face of normal environmental variation

Amensalism

interspecific interaction in which one species is harmed and the other is not influenced (-/0)

Amictic

when a lake almost never mixes

Ammonia gas (NH3)

ammonium ion (NH₄⁺) is converted to its toxic form, ammonia gas, at basic pH

Ammonium (NH4+)

an inorganic N compound; the ionic form of ammonia

Anaerobic

without oxygen; anoxic

Anoxic

without oxygen; anaerobic

Aquaculture

the farming of aquatic organisms

Aquifer

permeable deposit that can yield water by a well

Archaea

a domain of organisms, unicellular without organelles; one of three domains (super kingdoms) of organisms; distinguished on the basis of biochemical and genetic differences from the Bacteria and Eukarya

Attenuation coefficient

a value that indicates how rapidly light is absorbed

Autochthonous

originating within the system (e.g., organic carbon supplied by primary producers in the system)

Autotrophic

the capacity to perform primary production; self-feeding; able to use CO2 as a source of carbon using chemical (chemoautotrophy) or light (photoautotrophy) energy

Bacteria

a domain of organisms, unicellular without organelles; one of three domains (super kingdoms) of organisms; distinguished on the basis of biochemical differences from the Archaea

Bacterioplankton

suspended bacteria

Baseflow

the level of stream discharge in the absence of recent storms

Bathymetric map

a topographical map of a lake that indicates the distribution of depths and shape of the bottom

Beer’s law

law and associated equations relating light absorption to properties of the medium that light is traveling through; the law states that light absorption is linearly proportional to concentration

Benthic

associated with the bottom

Beta diversity (β diversity)

diversity between habitats; sum of species unique to each habitat when examining more than one habitat

Bicarbonate (HCO3-)

an ionic form of inorganic carbon that dissolves in water

Bicarbonate equilibrium

the chemical equilibrium involving the dissolved inorganic forms of carbon dioxide, carbonic acid, bicarbonate, and carbonate; the relative proportions of these ions depends upon pH

Bioaccumulation

bioconcentration plus the accumulation of a compound in an organism from food

Bioassessment

use of organisms to evaluate environmental quality

Biochemical oxygen demand (BOD)

the demand for O₂ created by compounds that can be respired by organisms plus the chemicals that will react with O₂

Bioconcentration

ability of a compound to move into an organism from the water

Biodiversity

the number of different species, organisms, genotypes, or genes of ecological functional groups in a region (also referred to as biocomplexity)

Biofilm

a film of organisms and associated materials attached to a solid surface (substratum)

Biomagnification

increase in concentration of a chemical at higher trophic levels of a food web

Biomass

mass of organisms

Biome

a large terrestrial area defined by its climate and dominant vegetation, however it is sometimes used interchangeable with ecoregion for freshwater systems.

Bioremediation

cleanup of pollution using organisms

Biotic sulfur oxidation

biotic oxidation of sulfur by chemoautotrophic organisms using oxidized sulfur to react with organic carbon and release energy

Bioturbation

stirring of sediments by movement and activity of sediment-dwelling organisms

Bloom

a large-dense population of algae

Bog

a wetland in which peat accumulates; with minimal inflow or outflow; supports acid-loving mosses such as Sphagnum

Bottom-up control

control of system productivity by nutrients or light

Brownian motion

molecules or particles moving independently at microscopic scales

Buffering

the ability of a solution to resist changes in pH (also known as buffering capacity) ¹³C, a stable isotope of carbon used in some ecological studies; naturally present in the environment at trace levels relative to the more abundant ¹²C

13C

a stable isotope of carbon used in some ecological studies; naturally present in the environment at trace levels relative to the more abundant 12C

Capillary fringe

belt of soil above groundwater that contains some water drawn up by capillary action; immediately above the water table

Carbonate (CO32-)

an inorganic ion with carbon that forms when CO₂ dissolves in water

Carbon dioxide (CO2)

a gas, a product of respiration

Carnivore

animal that eats other animals

Catchment (watershed)

surface area drained by a network of stream channels; although “watershed” is used synonymously, watershed has been defined in European literature as a line that joins the highest points of the perimeter of a catchment

Chemoautotrophic

obtains energy from chemicals other than organic C

Chlorophyll a

the primary pigment of photosynthesis in cyanobacteria and eukaryotic autotrophs; often used to indicate biomass; absorbs red and blue light

Chronic toxicity

toxicity with long-term exposure

Collector

an organism that makes its living collecting fine particles, either by filtering from the water column (collector-filterer) or feeding on deposited particles (collector-gatherer)

Commensalism

interspecific interaction in which one species is influenced positively and the other is not influenced

Community

all organisms in an area or a group of species in an area

Compensation point

 light level at which O₂ production by photosynthesis equals consumption by respiration, or CO₂ assimilation is equal to production by respiration

Competition

an interspecific interaction in which both species harm each other (- / -)

Competitive exclusion principle

the idea that only the competitively dominant organism will survive in an equilibrium environment

Conductivity

the ability of water to conduct electricity, a function of the number of dissolved ions in the water; measured in units of mhos (reciprocal ohms) or Siemens per unit distance

Confined aquifer

an aquifer between two impermeable layers (aquifuges)

Cultural eutrophication

a human-caused increase in a nutritive factor or factors leading to greater rates of whole-system heterotrophic or autotrophic metabolism

Cyclomorphosis

successive emergence of distinctive morphologies in the same species; often observed in microcrustaceans and rotifers

D_L

shoreline development index

Decomposer

organism that consumes or breaks down organic materials

Denitrification

conversion of nitrate to N₂ gas by microorganisms; a form of respiration that uses nitrate rather than O₂ to oxidize organic carbon

Density-dependent

factors that are a function of population size

Density-independent

factors that are not a function of population size

Detritivores

organisms that eat detritus; also called saprophytes

Detritus

decaying organic material

Diapause

part of the normal life cycle that is stationary, physiologically dormant and often resistant to environmental extremes such as drying or heat

Diatoms

single-celled algae with silica shell (frustule) and golden brown coloration (Bacillariophyceae)

Diel

24-h day with a light–dark cycle (as opposed to a period of consistent light)

Diffusion boundary layer

the thin aqueous layer near a solid surface where diffusion is dominated by molecular diffusion; its thickness can control metabolic rates of microorganisms

Diffusion coefficient

a constant used to describe diffusion of a compound or heat independent of distance and concentration

Diffusion flux

the amount of a compound diffusing across an area per unit time

Dimictic

a lake that mixes twice each year

Dinoflagellates

unicellular algae that move by means of flagella (Pyrrhophyta)

Discharge

the volume of a fluid flowing past a point per unit time

DNA barcoding

analysis of short genetic markers in DNA to identify species

Ebullition

release of bubbles

EC₅₀

concentration of a toxin which induces a response halfway between baseline and maximum after a given time period

Eckman dredge

a dredge that is lowered to the bottom, with a messenger that is sent down its line and triggers jaws on the bottom to shut, taking in sediment

Ecoestrogens

organic compounds that mimic natural estrogen and lead to endocrine disruption; oestrogens or environmental estrogens

Ecosystem engineer

organisms that strongly alter their environments

Ecosystem services

services of value to humans associated with ecosystem processes

Eddy diffusion

diffusion by transport or mixing of a diffusing substance or heat; much faster than molecular diffusion; also called transport diffusion or advective transport

eDNA

environmental DNA, used to help detect organisms in their environment

Effective concentration (EC)

the concentration of toxic substances that causes some other effect other than death

Effluent

the water released from a sewage plant, factory, or other point source

Emergent

growing above the water

Endemic

species having a distribution that is restricted to a relatively small region