1-6: The Hydrosphere, Water Flashcards
Definition of ecology
The scientific study of the interactions that determine the distribution and abundance of organisms.
Definition of the environment
Biotic and abiotic factors outside the organisms
Definition of abundance
The population size
Definition of distribution
Where organisms are found
What is population ecology?
Study of trends and fluctuations in the number of individuals of a particular species at a particular time and place.
Looks at birth and death rates, predators and prey
What is ecosystem ecology?
Entire lakes, forests, wetlands, etc
What are observations?
Changes in abundance or system functioning over time or space, often using comparisons
Methods of approach
Observations
Experiments
Mathematical models
What is an ecosystem?
A biological community of interacting organisms and their non-living environments
What is central to biomes?
The soil ecosystem
How much of the earth’s surface is made up of water?
70%
The 3 process that keep water moving in the water cycle
Evaporation: water is heated by the sun
Condensation: vapour forms clouds
Precipitation: water falls as rain, hail, snow, sleet
How much of the earth’s water is freshwater lakes, rivers, and streams?
0.25%
Why is freshwater important to the biosphere?
Moves water in and out of ecosystems
Transports natural substances, eg. nutrients
Why is freshwater important to humans?
Transport
Irrigation
Disposal of waste
What is plankton?
Floating microorganisms
Movement depends on currents
Found in freshwater and marine
What is nekton?
Swimming microorganisms
Navigate at will
Swim faster than current
What is neuston?
Microorganisms resting or swimming at the surface
What is an epipelic biofilm?
A film on the surface made of algae, fungi and bacteria
What does epibenthos mean?
Attached to or clinging to plants
eg. crabs, snails
What does benthos mean?
Attached/living in or on bottom sediments
What communities do you find in lakes and ponds?
Plankton
Nekton
What communities do you find in flood plains?
Plankton
Nekton
What communities do you find in permanent wetlands?
Benthos
What communities do you find in mudflats?
Epipelic biofilms
What freshwater invertebrates do you find in rivers and streams?
Flatworms Molluscs Segmented worms Crustacea Insects- mayflies, stoneflies, etc
What do worms indicate?
Poor water quality, as they are found in low O2
What do mayflies indicate?
Good water quality, as they are found in high O2
Zooplankton features
From 0.3-3.2mm
Feed on phytoplankton
Eg. copepods, rotifers, crustaceans
Phytoplankton features
The abundance dictates the colour of the water
Very green = bloom
Shredder examples
Caddis flies
Isopods
Crayfish
Grazer examples
Mayflies
Gastropods
Collectors in the water column examples
Diptera
Trichoptera
Collectors in the sediment examples
Worms
Diptera
Bivalves
Predator examples
Leeches
Stoneflies
Dragonflies/damselflies
Beetles
Properties of lakes and ponds
Stratification
Wind-induced turbulence
Properties of floodplain wetlands
Periodic desiccation
Competition between algae and macrophysics
Properties of permanent wetlands
Periodic flooding
Properties of estuary mudflats
Desiccation
Exposure to salt water
Competition at mud surface
Properties of estuary outflow
Mixing with salt water
Turbidity
Grazing in the water column
How does river classification work?
The larger number, the further down the river the part is
Eg. 4th order rivers are much bigger and towards the end than 1st order, which are by the source
River flow is unidirectional
What is a riffle?
Fast flowing river over rocks, shallow
Home to organisms with adaptations to anchor to rocks, logs and other debris
What is a pool?
Slow flowing river over sediment, deep
Often hold fish eg. trout
Study in Santa Barbara: 31 found in pools, only 18 in rapids
What is a run?
Like a riffle, but with smooth surface for light to penetrate
Deeper than riffles
Trout use them for feeding as don’t need much energy to fight currents
What is thermal stratification?
When there is a change of temperature at different depths of a lake
There is also oxygen depletion due to reduced re-aeration from the atmosphere
When can stratification occur?
Not in rivers- too fast flowing and shallow
Can occur in slow, deep-flowing rivers
What are the river classifications based on nutrient richness?
Oligotrophic
Mesotrophic
Eutrophic
Hypereutrophic
What does oligotrophic mean?
Low N and P
Low biomass
Typically deep
What does mesotrophic mean?
Moderate amount of nutrients
What does eutrophic mean?
High N and P
High biomass
Typically shallow
Properties of water
Wide temperature range- liquid form for most of the year
Wide density range- limits the rate of sedimentation
High absolute viscosity- limits the mixing of water, sedimentation of biota, and flow in lotic systems
High surface tension- allows attachment of invertebrates to the surface eg. pond skaters
What is an environmental gradient?
A gradual change in abiotic factors through space and time
Eg. altitude, temperature, depth, soil humidity
Species abundance usually changes along environmental gradients
What is an ecotone?
A transitional area of vegetation between two plant communities
It has some characteristics of each bordering community
Features of a high-gradient stream
Steep sloped Narrow V-shaped valleys 'Young streams' Rapid water flow Can erode
Features of a low gradient-river
Sluggish moving waters
Carry small amounts of very fine sediment
Wider, less rugged valleys
River can meander
Biological role of Carbon
Photosynthesis
pH
Biological role of Oxygen
Aerobic respiration
Oxidation reactions
Biological role of Nitrogen
Amino acids/proteins
Ammonia and nitrate
Limiting
Biological role of Phosphorus
Nucleotides (DNA, RNA, ATP)
Polyphosphates
Limiting
Biological role of Silicon
Cell wall of diatoms and other algae
Limiting
Where is most nitrogen?
Fixed in the soil
What fixes nitrogen in water?
Cyanobacteria (blue-green algae)
Occurs in heterocysts
Where is inorganic nitrogen gained from in lakes?
Groundwater and surface run-off
Largely NO3- and NH4+
What is NH4+ influenced by
pH
What is the main source of phosphorous (P) to plants
Phosphate (PO4)
What is P availability increased by
Low dissolved oxygen
Low pH
Features of a deep (over 5m) lake
Have a photic zone- a part of the water column receiving sunlight
Distinction between shoreline (littoral) and central zone
In photic zone, get macrophytes and algal mats
In aphotic zone, get mainly bacteria
What is the littoral zone?
Where land meets water
Enough light for plants to grow
What is the pelagic zone?
Open water
Too deep for rooted plants to grow
What is the benthic zone?
Bottom of the lake
Animals live here
Thick mud at bottom
Profundal/abyssal zone
Deepest part of the open water
Only in lakes over 200m deep
Shallow (under 6m) lake features
Photic zone is the whole of the water column
Too shallow for stratification
Benthic community as light can penetrate
Erosional rivers/streams features
Photic zone is throughout water column
There is more allochthonous material than autochthonous
What does allochthonous mean?
Imported material, eg. leaves
What does autochthonous mean?
Produced within system, eg. phytoplankton
Depositional rivers/streams features
Photic zone is throughout water column
More autochthonous input than allochthonous
Low flow, fine sediment
Anoxic conditions
What are lakes influenced by?
Structure (morphology) and hydrology (flow in/out of the lake)
Interactions with surrounding environment
Climate
Structure of lake basin is important for…
Water flow
Nutrient accumulation
Light penetration
Mixing of the water column
What is holomictic mixing?
Mixes from top to bottom
What is meromictic mixing?
Does not completely mix
Typically very deep lakes
What is monomictic mixing?
Does not freeze
One long mixing period throughout winter
What is dimictic mixing?
Mixes once in autumn, once in spring
Covered in ice in winter
What is polymictic mixing?
Mixes frequently throughout the year
Usually shallow lakes
What is amictic mixing?
No mixing
Covered in ice all year round
Winter stratification of Rostherne Mere
No surface warming
Wind-induced mixing
No stratification
Summer stratification of Rostherne Mere
Surface warming
Less wind-induced mixing
Stratification
Winter phytoplankton primary production (PP) in Rostherne Mere
Low PP due to low light and temperature
Spring PP in RM
Increased PP
Winter nutrients in RM
High N and P due to a low PP
Spring nutrients in RM
Decrease, due to an increased PP
Diatom features
Unicellular/colonial
Adapted to low light and low temperature
Require silicon
Green algae features
Unicellular/colonial
Require high nutrients and stratified water
Dinoflagellate features
Unicellular
Adapted to high temperatures and low nutrients
Cyanobacteria features
Blue-green algae
Usually colonial
Adapted to high temperatures, low light and low nutrients
Resistant to grazing- only eaten by rotifers and protozoa
Cyanobacteria pigment
Chlorophyll-a
What is Anabaena?
A cyanobacteria
Three specialised cells:
1. Vegetative cells: have gas vesicles which provide buoyancy and allow light absorption
2. Spore-resisting stages and can adapt in harsh conditions
3. Heterocysts capable of nitrogen fixations
Zooplankton bloom
Peak in spring
Clear water phase when phytoplankton have all been eaten
Name for flowing water
Lotic
Name for standing water
Lentic
Lotic water features
Shallower than most lakes
Fast, unidirectional flow
Less likely to have stratification
Not influenced by phytoplankton/zooplankton
What happens at the erosional zone?
Water velocity is high
Net re-suspension
What happens at the depositional zone?
Water velocity is low
Net deposition
Impact of high water flow on benthic microorganisms
Organisms are dispersed
Nutrients are dispersed
Create microenvironments
What animals do you find with a small particle size?
Deposit feeders
Eg. midge larvae
What animals do you find with a large particle size?
Predatory species and grazers
Eg. stoneflies, mayflies
What animals do you find in detritus?
Lots of collectors
What is the drainage basement/watershed?
The total area drained by tributaries that feeds a main channel
What is a river system?
A network of streams that drains an area of land
Main river + tributaries
What are tributaries?
Smaller streams/rivers that flow into larger ones
3 types of biota found in lotic systems
Phytoplankton
Periphyton
Macrophytes
Where is phytoplankton found?
Slow flowing rivers
High temperatures, high light intensity
What is periphyton?
Lives on substrate or larger plants
Unicellular and filamentous algae
What are macrophytes?
Large plants
Floating-leaved: eg. Duckweed
Free-floating: not rooted to substrate, eg. Water fern
Submerged: eg. Water crowfoot
Fish adaptations to running water
Streamlining- both ends are narrow
Flattened ventral surfaces
Live around large stones and boulders
Refuge in overhanging trees and macrophytes
Different dissolved oxygen (DO) requirements
Major invertebrate taxa in running waters
Leeches Worms Snails Bivalves Water louse Water shrimp Midges Mayflies Stoneflies Beetles
What breaks down large allochthonous particles?
Shredders
What do the filterers and collectors eat?
Fine organic particulate material (FPOM)
Adaptations to running water
Differing O2 LC50s (lethal conc of O2 required to kill 50% of the population) Flattened body Hooks on limbs/other parts of body Streamlining Orientate themselves to flow
