Glossary - Freshwater Ecology: Concepts and Environmental Applications - page 486

Bacterioplankton, suspended bacteria
Bailer, a tube with a one-way valve on the bot-
tom (allowing only inflow of water) used to
sample well water
Baseflow, the level of stream discharge in the
absence of recent storms
Bathylimnion, the deepest part of a strati-
fied lake
Bathymetric map, a topographical map of a
lake that indicates the distribution of depths
and shape of the bottom
Bed load, sediment transported by rolling, slid-
ing, or saltation on or close to the stream or
river bed
Benthic, associated with the bottom
Bicarbonate, HCO 3 , an ionic form of inor-
ganic carbon that dissolves in water
Bicarbonate equilibrium, the chemical equilib-
rium involving the dissolved inorganic forms
of carbon dioxide, carbonic acid, bicarbon-
ate, and carbonate
Bioaccumulation, bioconcentration plus the ac-
cumulation of a compound from food
Bioassessment, use of organisms to evaluate
environmental quality
Biochemical oxygen demand (BOD), the de-
mand for O 2 created by compounds that
can be respired by organisms plus the chem-
icals that will react with O 2
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 attached to a solid
surface (substratum)
Biogenic meromixis, an increase in the density
of the hypolimnion caused by dissolved ma-
terials released from sinking organic matter
so that mixing cannot occur
Biologically available phosphorus (BAP), the
amount of phosphorus that can be used by
organisms; can refer to the instantaneously
available phosphate or the P that will become
available with long-term decomposition
Biomagnification, increase in concentration of
a chemical at higher levels of a food web

Biomanipulation, to improve water quality by
controlling the fish community
Biomass, mass of organisms
Bioremediation, cleanup of pollution using
organisms
Biotic oxidation, oxidation of compounds by
organisms
Bioturbation, stirring of sediments by move-
ment and activity of sediment-dwelling
organisms
Bittern, bromide, magnesium, and chloride
blend left when seawater almost completely
evaporates
Bivoltine, producing two generations annually
Blackfish, species that are resistant to deoxy-
genated conditions and survive in standing
floodplain water during dry periods
Blackwater, river water colored by dissolved
organic matter (humic substances) low in
dissolved inorganic and suspended solids
and usually with a low pH
Bloom, a large population of algae
BOD, see biochemical oxygen demand
BOD 5 , oxygen consumed in 5 days by biolog-
ical and chemical processes
Bog, a wetland in which peat accumulates; with
minimal inflow or outflow; supports acid-
loving mosses such as Sphagnum
Borehole, a hole drilled to sample geological
material or for well installation
Bottomland, lowland along a stream or river
that is flooded periodically
Bottom-up control, control of system produc-
tivity by nutrients or light
BPOM, benthic particulate organic matter
Brackish, saline water with salinity less than
that of seawater, as low as 100 ppm
Braided stream, a stream having elaborate,
multiple channels rather than one large
channel
Brine, water more saline than seawater
Brook, small stream
Brownian motion, molecules moving indepen-
dently at microscopic scale
Brownwater, New Zealand term for
“blackwater”