EBF Temperate Streams and Lakes

lotic system

flowing water down a gradient

• stream, river, creek

lentic system

still or near still flow

• lakes and ponds

physical characteristics of streams

• chemistry

• temperature

• gradient

• stream size

all dependent on geography and geology

watershed

topographic area of land draining to a single point via surface or groundwater flow

5 ecoregions of Georgia

1. Appalachian plateau

2. valley and ridge

3. blue ridge

4. piedmont

5. coastal plain

14 Georgia river basins

the Altamaha, the Chattahoochee, the Coosa, the Flint, the Ochlockonee, the Ocmulgee, the Oconee, the Ogeechee, the Satilla, the Savannah, the St. Mary’s, the Suwannee, the Tallapoosa and the Tennessee

cold water

temperature rarely exceeds 24 degrees Celsius (75 degrees Fahrenheit) for extended periods of time

warm water

a freshwater system that seasonally exceeds 24 degrees Celsius (75 degrees Fahrenheit)

gradient

the slope or steepness of a stream channel, measured as the vertical drop in elevation over a horizontal distance (rise over run)

Strahler stream order

a top-down dendritic classification of river systems to identify a hierarchy of tributaries within the system

• 1st order + 1st order = 2nd order

• 2nd order + 2nd order = 3rd order, etc.

river continuum concept

model for classifying and describing riverine ecosystems,

• a river is dependent on upstream inputs

• biotic complexity changes as the river gets larger

• increased diversity and primary productivity as a system moves downstream and grows in size

headwater streams

• higher input from terrestrial environment

• lower fish diversity

• high insectivory

mainstem large river

• higher primary productivity

• higher fish diversity

• higher piscivory

pool

areas of slow flowing, deep water, often on the outside of the bends

runs

smooth unbroken flow, connecting riffles and pools

riffles

fast, shallow flow, over boulders and cobbles, which break the water surface

resource partitioning

differential use of resources in time and space to minimize overlap in niches

• spawning partitioning

• forage partitioning

rheotaxis

orientation into stream current

• positive = orients body into oncoming current

• negative = orients away from oncoming current

drift feeding

strategy where fish face upstream to catch prey items carried by the current

• interspecific and intraspecific competition

• aggression use to maintain position in water

threats to temperate streams

point and non-point source pollution

• changes chemistry and water quality

• alters communities

connectivity

• dams, culverts limit fish passage

• alter flow and sediment transport

global climate change and stream temperature

lake

natural basin of freshwater surrounded by land, not connected directly to the ocean

pond

smaller lake

reservoir

a man-made basin of freshwater typically created by impounding a lotic system

physical characteristics of lakes

• light

• temperature

• water movement and stratification

• chemistry

• lake size

primary producers in lakes

• microscopic algae

• macroscopic algae (mostly green)

• true plants (floating, emergent, submerged)