Aquatic Ecology all weeks (2, 3, & 4)

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