1/99
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
lotic systems
refers to flowing H2O ecosystems. ex: streams/rivers
what are the features that characterize streams and rivers from other aquatic environments?
unidirectional flow. linear form. fluctuating damage. unstable channel & bed morphology
river channels are self formed/maintained
shaped by climate, geology, weathering, and fluid flow forces. flowing water results in continually changing physical environment
what direction is the ecology of rivers/streams in?
longitudinal direction, rather than the vertical directions (as seen in lentic system)
where is the greatest change in lotic systems?
although slight differences in temp can exist between surface and bottom waters of deep lotic systems, greatest changes take place as H2O moves downstream.
flowing H2O vs. lentic systems
flowing H2O systems possess greater habitat heterogeneity (diversity) than lentic systems
what does both permanence and heterogeneity lead to?
increased species diversity
what does narrow, linear form of rivers and streams result in?
results in closer links to many more surrounding terrestrial ecosystem than is the case for a lake or ocean. this has ramifications for many aspects of running H2O ecology
what specific characteristics are lotic systems recognized by?
H2O flow that's typically unidirectional and variable in rate of flow. state of constant physical change due to changing H2O and it's volume. plants and animals that have adapted specific traits for surviving in this ecosystem. large variety of micro-inhabitants
streams
body of H2) confined in a channel that moves under influence of gravity
drainage basin
total area drained by given stream
stream velocity
governed by gradient it varies w/gradient and channel size
what do streams transport solid material as?
dissolved loads. bed load. suspended load
bed load
may move by saltation (lifting of grains off bottom) or traction (rolling rocks along bottom)
what are the three main types of streams?
perennial. intermittent. ephemeral.
perennial streams
have H2O flow in stream channel throughout year and substantial inputs from ground H2O
intermittent streams
canals have relatively high inputs of ground H2O but flow in stream channel can be for several weeks or months each year
ephemeral streams
only flow after precipitation events. channel is generally well above H2O table and these streams flow only few hours or days
stream order
classification of streams based on tributary junctions, useful indicators of stream size, stream discharge, and drainage area
what does a stream's order correspond to?
it's rank/position within a watershed/network
combining of tributaries
smallest unbranched tributaries designated order 1. where two first order streams join a second stream segment formed. where two second order segments join, 3rd order segment and so on
what are examples of characteristics that change as stream order increases?
channel shape. habitat. drainage area. biological communities
stream channels tend to...
meander through watershed forming riffles, pools, and bars in response to geologic conditions that affect H2O depth and velocity
pools
act as areas of deposition, where H2O velocity decrease and particulate matter settles. pool sediments tend to be finer and more homogeneous
riffle
as H2O flows out of pools, velocity increases. creating shallow, rapidly flowing H2O (riffle). sediment in riffle areas tend to be more coarse and heterogeneous
bars
pools also form @ bends in stream channel where H2O scours out bottom of channel. sediment eroded from this area is deposited on opposite bank forming bars. bars are temporary and poor habitats for bottom dwelling organisms b/c of unstable, shifting nature
erosion/source zone (headwaters)- mountain streams characterized by
steep slopes. v shaped river valleys. waterfalls/rapids. moving large size sediments.
transition/transfer zone characterized by
lower altitude. slower flow velocity. meandering and wider river bed. erosion and settling of larger sediments.
deposition zone characterized by
shallow, gentle slope. slow flow velocities. wide meanders. settling fine sediments. many arms of the river
tributary system (erosion zone)
erosion zone is upper reach of a river basin. AKA youthful stage. river generally has steep sides/steep gradient (unless basin was formed by glaciers), waterfalls, rapids, and deep gullies
main trunk (transition zone)
transition zone occurs in mature stage of river. mature river runs slower, continues to erode but also deposits more material on river floor, causing creation of plains, and is changing course continually (no longer straight)
mouth (deposition zone)
deposition zone has a hydraulic gradient. AKA old age river stage. deposition zone is characterized by foodplains, oxbow lakes, and deltas
what are the 4 main type of river channels?
straight. braided. anastomosed/anastomosing. meandering
riparia
refers to lotic ecosystems. riparia flora and fauna often highly adapted and specific to lotic ecosystems
what are the 2 main classifications of riparian habitats?
upland. lowland
upland
cold, clear, rocky, fast flowing rivers and mountainous/steep ground
lowland
warm, slow flowing rivers in flat lowland area. H2O frequently colored by sediment and organic matter
upland encourages fish species
clear, cool, fast flowing H2O of upland riparian habitats encourage fish species with limited temp tolerances, high oxygen needs, strong swimming ability, and specialized reproductive stages (to prevent eggs or larvae being swept away)
what do the characteristics of upland habitats also encourage?
encourage invertebrate species w/similar characteristics and ecologies revolving around coarse sediments and interstices (gaps) between sediments
lowland encourages fish species
turbid, warm, slow flowing H2O and fine sediments of lowland riparian habitats encourage fish species with broad temp tolerances, greater tolerances to low oxygen levels, and life history/breeding strategies adapted to other traits of lowland rivers (seasonal H2O volume and turbidity changes)
invertebrate species adapted to lowland
lotic systems have ecologies revolving around fine sediments or alternate habitats: submerged woody debris and submerged macrophytes
what are the 4 main constituents living environment in lotic systems?
elements and compound: of ecosystems that are absorbed as food source or for respiration, many are required by plants and passed along food chain. autotrophic plants and bacteria: are primary producers, as they produce new energy into ecosystem. consumers. decomposers
lotic environments offer numerous microhabitats w/favorable conditions for many types of animals
animals in this ecosystem undergone ongoing evolutionary adaptation better suit this environment. some of these animals sessile. animals usually small and include protozoans and some fresh H2O sponges. obtain food via tentacles which trap microscopic organisms that's flowing downstream
suckers
animal adaptation. attach themselves to surface that keeps them into position. also assist in movement.
hooks/claws
animal adaptation. dig into object and allow animal cling to position/claw way around surface
body flattening
animal adaptation. allows animal in the H2O bear less of brunt of the force of H2O moving downstream. also allows to enter confined areas
streamlining
animal adaptation. less resistance presented by the running H2O when animal attempts to move
flight
animal adaptation. allows remove from force current @ ground level and move upstream more easily if needs be
plants species in lotic
diversity of plant species in lotic community is small compared to lentic communities although communities have very similar compositions
tree canopies (river domes)
riparian vegetation significant component. along smaller rivers may completely cover and overshadow riverbed, while this effect only partial along larger river. tree doming of temp and sunlight penetration, which favors the development of phytoplankton
river bank consolidation
riparian vegetation significant component. river bank consolidation and prevention of coastal erosion
roots riparian vegetation
riparian vegetation significant component. serves as a filter that absorbs nutrients dissolve in ground H2O before reaching river. this can clean up to 80% of nutrient pollutants that would otherwise flow into river
vegetations in catchment basins
riparian vegetation significant component. vegetations in catchment basins considerably slows down rainwater runoff to the river, thus decreasing risk of a high tide
abundant vegetation
riparian vegetation significant component. abundant vegetation controls evaporation from earth surface and keeps groundwater near surface
lotic wildlife, rivers, migration, and feeding/breeding
lotic wildlife often migrate for feeding and breeding purposes and according to river flow both upstream and downstream river
lotic wildlife, rivers, migration, and unfavorable river sections
ability to migrate enables lotic wildlife to avoid unfavorable river section, ex: polluted places, gravel pits, etc. allows lotic wildlife to go back and recolonize area where conditions restored
lotic wildlife, rivers, migration, and migration corridor
rivers important migration corridor. continuous belt of riparian vegetation provides interlink for many animals in course migrations. river corridors often only natural link between certain ecosystems (savannahs, forest area, and mountain passes) and so they are influential to survival of large number of plants and animals
lentic system
refers to aquatic bodies containing stagnant/still waters
where are lentic waters usually formed?
depression on earth's surface where H2O is trapped and has no exit of flow
what are examples of lentic systems?
ponds. lakes. swamps
what type of system is lentic system?
closed system. most aquatic life that enters these systems rarely leave
what are the two main types of lentic systems and how are they differentiated?
ponds and lakes. by size, depth (zonation), chemistry/salinity
what are lentic systems primarily?
fresh water bodies. others same various type of salinity
what are lakes and ponds almost always connected with?
streams in the same watershed. but streams not always connected to lakes or ponds
glacial lakes
glaciers can form lakes formed from glacier processes (glacier weight and movement)
tectonic basins
lake type. lake basins formed due to movement of earth's curst
volcanic lakes
lake basins formed from volcanic processes
landslide lakes
lakes formed from rockfalls or mudslides that dam stream or rivers for periods between year and several centuries
solution lakes
lakes found in areas w/limestone deposit where percolating H2O creates cavities
plunge pools
lake type. lakes were formed when waterfalls scour out deep depressions and pools
oxbow lakes
where rivers/stream have meandered across low gradients. oxbows can form in areas where former channel has become isolated from rest river
human made lakes
created from damming rivers and streams
how are lentic waterbodies zones created?
light penetration. depth/temp (depth affects temp). productivity (nutrient richness and turnover)/trophic status
zonation
the distribution of plants or animals into specific zones according to such parameters as altitude or depth, each characterized by its dominant species.
what can lakes be divided into and what is it based upon?
divided into horizontal and vertical zones. based upon light penetration, temp, and chemical characteristics
what does morphology determine?
physical look of basin often determines which zones are present and their extent
littoral zone
region near shore where sufficient light can reach the bottom to support rooted plants. in shallow lakes/ponds this zone may extend completely across basin. several communities within littoral region
emergent vegetation
found near the shoreline. grasses, rushes. sedges.
floating vegetation
as depth increases a transition occurs to plants w/long stems or petioles and floating leaves.
submerged vegetation
innermost region of littoral zone, where plants fully submerged
limnetic zone
area open water surrounded by littoral region. zones determined by light penetration
trophogenic zone (limnetic zone)
part of limnetic region which gets sufficient sunlight for photosynthesis to exceed respiration (P > R)
compensation point (limnetic zone)
part of limnetic zone. border between each zone, where P=R
tropholytic/profundal zone (limnetic zone)
part of limnetic region where respiration is greater than productivity (P<R). H2O in this zone is colder, darker, and less oxygenated
seasonal affects of lakes and larger ponds
experience seasonal shifts in temp due to heating and cooling surface waters in the basin
warmer seasons and solar
during the warmer seasons, increase in solar radiation and warmer air temps heat surface waters faster than deep water
stratification
surface H2O becomes lighter as its temp rises, creating layer of lighter, warm on top of denser cooler water
epilimnion
upper most region warm circulating H2O. all lakes and ponds have an epilimnion layer
metalimnion
central zone of rapid temp change (thermocline)
hypolimnion
or the profundal zone. deeper, colder, still bottom waters
monomictic lakes
typically found in subtropical regions, where H2O temp rarely fall below 4 degrees celsius
oxygen and stratification
deprived of oxygen rich waters above the nutrient rich hypolimnion often becomes anoxic, due to depth from surface. oxygen depletion continues throughout stratification
surface waters cooling down
as the surface waters cool in colder seasons density barrier (metalimnion) between epilimnion and hypolimnion disappears ---> 2 layers begin to mix ---> oxygen rich H2O carried downward, nutrient rich H2O is taken up
what do the surface waters cooling down result in?
often results in photosynthetic explosion in trophogenic (littoral) zone, causing rapid increase in algae; known as algal bloom
how many mixing periods do dimictic lakes have?
2 mixing periods. warm season and cooler season
where do dimictic lakes occur?
temperate zones
how are dimictic lakes and monomictic lakes similar?
they stratify during warm seasons
what happens to stratification during cold weather?
destroys stratification and complete circulation occurs
what happens when surface H2O gets cool enough?
once it gets cool enough to freeze a film in the ice forms and circulation stagnates
warmer seasons circulation
during warmer seasons the ice melts w/exposure to wind and sun causing circulation to resume