Glossary - Freshwater Ecology: Concepts and Environmental Applications - page 499

Specific runoff, precipitation runoff per unit
catchment area
Spectrophotometer, an instrument that mea-
sures the absorption of light as a function
of wavelength
Spherical collector, having the form of a sphere
or part of a sphere; spherical irradiance col-
lectors are used to estimate total light avail-
able to photosynthetic plankton
Spiraling length, horizontal distance on a river
or stream between successive uptake or re-
lease events (nutrient spiraling)
Spring mixing, lack of differences in tempera-
ture with depth allowing wind to mix an
entire lake during spring
SRP (soluble reactive phosphorus), a chemi-
cally determined fraction containing phos-
phate and other forms of orthophosphate;
also called DRP (dissolved reactive
phosphorus)
Stability of stratification (S), the energy re-
quired to blend a body of water to constant
density without adding or subtracting heat;
expressed as g-cm cm 2 of lake surface
Stable isotope, natural form of an element that
does not emit radioactivity
Stenothermial, able to survive in only a limited
range of water temperatures
Stock, size of population
Stoichiometry, the ratio of elements to each other
Strahler classification system, used to describe
locations in dendritic patterns of stream
drainage systems; first-order streams are
those without tributaries, second-order
streams are the result of two first-order
streams joining, third-order streams are the
result of two second-order streams joining,
and so on; a smaller order entering a larger
order does not change the numeric designa-
tion of the larger
Stratification, density differences in water that
can maintain stable layers
Streamline, the path of a fluid particle relative
to a solid body past which the fluid is mov-
ing in smooth flow without turbulence
Streamlined, shaped to avoid causing turbulence
Stream order, classification of streams; the most
commonly used system is the Strahler system

Stygobite, obligate groundwater dweller; not
found in surface waters
Styigophile, groundwater organism with adap-
tations to living in groundwater, but also
found in surface waters
Sublethal, not causing death
Sublittoral, bottom region between littoral and
profundal zones
Submersed, a macrophyte that grows below
the water surface
Succession, the sequence of organisms that colo-
nize and inhabit a disturbed habitat over time
Sulfide, sulfur ion, S 2
Summer stratification, in temperate lakes the
hot period in which the lake water is in sta-
ble layers of discreet temperatures
Supersaturation, containing dissolved materi-
als in excess of equilibrium concentrations
Surber sampler, an apparatus with a square,
fixed-area frame (1 ft 2 or 0.1 m 2 ) hinged to
another frame that has a net; the open first
frame is located on the stream bed, the net
is elevated to a vertical position, and rocks
caught in the open frame are rubbed and
shaken to allow stream flow to move or-
ganisms into the net
Surface area to volume relationships, a geo-
metric ratio that can be used to indicate the
ability of an organism to exchange materi-
als with its surroundings
Surface tension, hydrogen bonding pulls water
into a tight surface
Suspended load, fine materials suspended in
water under normal flows
Suspended particles, material retained by a
0.45- m filter that stays suspended (seston

in streams)
Swamp, wetland dominated by woody vegeta-
tion (United States) or forested fen or
reedswamp (Europe)
Symbiosis, two organisms that live in close
proximity; does not determine interaction
effect; incorrectly used by some to refer to
mutualism
Synecology, older term for study of communi-
ties (as opposed to single species)
Syntrophy, a group of organisms with compli-
mentary metabolic capabilities; characteris-
tic of anoxic microbial communities