Exam Questions Flashcards
How is coarse particle organic matter broken down?
Shredders break down CPOM (eg leaves,twigs,macrophytes) feeding on bacteria and aquatic fungi.
Give examples of shredders that break down CPOM.
Gammatids
Plecoptera
Trichoptera
How big are COPM?
Greater than 1mm in size.
Where do CPOM collect and gather?
In front of boulders with small woody debris or settle in pools.
What is CPOM dominated by?
CPOM is dominated by macro invertebrate shredders and collectors.
How do shredders break down the CPOM?
They chew large organic matter and assimilate 40% and pass 60% as faeces (Fine particulate organic matter) (FPOM)
What factors determine changes in functional feeding groups (macro invertebrate communities) ?
Amount and type of organic matter entering the river (CPOM)
What percentage of organic input does CPOM contribute to the River Continuum concept (RCC)?
Upwards of 90%
Headwaters include what organic matter?
CPOM and FPOM
Provide a detailed account of seasonal thermal stratification in temperate lakes.
Spring-
- Incoming light energy is converted directly in to heat.
- Ice cover decreases in thickness and breaks up.
- Temperatures in spring rise and water temperature increases.
- Little resistance to mixing.
- A process driven by wind energy and convection.
Provide a detailed account of seasonal thermal stratification in temperate lakes.
Summer-
- Intensity of solar radiation increases = water temperature increases = density decreases.
- Wind and surface generated currents distribute this heat vertically within the lake but only to a limited depth.
What are the three layers in stratification?
- Epilimnion
- Thermocline
- Hypolimnion
Is there free mixing and temperature variation within the layers?
- Within each of the three layers there is free mixing and little temperature variation
however
- Between layers there is little mixing and clear temperature differences.
What causes a thermocline in freshwater lakes?
The significant difference in density between the warmer surface layer (Epilimnion) and the colder bottom layer (Hypolimnion) results in stratification causing a thermocline.
What causes stratification to occur in freshwater lakes?
The significant difference in density between the warmer surface layer and the colder bottom layer results in stratification.
What kind of water is Lentic?
Standing water
What kind of water is Lotic?
Running water
What does Abiotic mean?
Non living
Key physical abiotic factors
- Water levels/depth
- Temperature and light
- Flow/Velocity of current
- Turbidity
- Water Colour
- River width and wetted width
Key physical abiotic factors pt 2
- Substrate size and type
- Geology and soil type
- Catchment land-uses and management practices
- Rainwater composition
Key chemical abiotic factors
- pH
- Dissolved oxygen (mg/l)
- Conductivity
- Alkalinity
- Hardness
- Nutrients (nitrate, phosphate, total phosphorous)
- Organic matter
What does Biotic/Biota mean?
Living
What are the key biotic factors?
- Micro organisms : bacteria/fungi
- Phytoplankton
- Macrophytes, trees, mosses
- Invertebrates: sponges, worms, snails, insects
- Birds
- Fish
- Mammals
What are Trophic interactions?
The classification of organisms based on their feeding habits and relationships.
Give an example of Freshwater food web
1- Fish - territory consumer / predators
2- Macroinvertebrates- secondary consumers/ predators
3- Microscopic zooplankton - primary consumers/ herbivores
4- Microscopic phytoplankton - primary producers
What is a Biogeochemical cycle?
It is the cyclic path nutrients take within an ecosystem to flow between the non-living, the living, and back to the non living components.
Describe the biogeochemical cycle
Output from one ecosystem is the input of another.
Nutrients are exported from terrestrial to freshwater ecosystems, and from freshwater to marine ecosystems
Name the three components to every biogeochemical cycle.
- Inputs
- Internal cycling
- Outputs
What do the inputs, internal cycling and outputs act as?
Sources of nutrients
What are the stages in the biogeochemical cycle diagram?
(1. Net primary productivity
2. Internal cycling )
-Litterfall
-Dead organic matter (output)
-Decomposition
-Soil nutrients(output)
(Input-from the weathering of rocks and minerals)
- Plant uptake
-Incorporation into plant tissues
What are the key processes involved in internal cycling of nutrients (biogeochemical cycle)
Net primary productivity and decomposition
What are the two basic types of biogeochemical cycling?
- Gaseous
- Sedimentary
Describe the gaseous cycle
-The atmosphere and the oceans are the primary sources of nutrients e.g. Nitrogen, Oxygen, Carbon
Describe the sedimentary cycle (biogeochemical)
- The dominant sources are rocks, soils and minerals eg Phosphorus.
- Based on the primary source of nutrient input to the ecosystem.
- Driven by the flow of energy in the ecosystem.
- Tied to the water cycle.
What water is lotic?
River and stream
What are the characteristics of lotic systems?
- Unidirectional flow with variable velocity(speed)
- Linear form with changing gradients
- Erosion and deposition
- Complex variable channel
- High stream variability
How are lotic systems classified?
The Strahler classification method
Describe the Strahler Classification method.
1st order- single, Unbranched headwater channels
2nd order- when two 1st order streams meet
3rd Oder - when two 2nd order streams meet
What are the dominant physical factors that determine the nature of rivers ?
Flow and Substrate
How is the physical habitat of the lotic ecosystem channel size determined?
Flow
- the volume of the water
- the velocity(speed of the water)
- flow and weather
- flood flows
How is substrate determined in the nature of rivers?
- Inorganic substrates e.g. sand and boulders
- Organic eg leaves , fallen trees, aquatic plants
What are wetlands?
They are Lentic standing waters that are defined as areas of land whose characteristics are determined by the presence of water, either permanent water logging or through seasonal flooding.
What are the benefits of wetlands?
- Support specialised plant communities where soil conditions remain saturated for most or all of the year.
- Supports a diverse community of invertebrates.
- Fish in these wetlands are a good base for birds
- Amphibians and reptiles inhibit the emergent growth , soft mud and open waters of marshes and swamps
What are the three freshwater wetlands ecosystems?
- Riverine eg oxbow lakes
- Lacustrine eg slow flowing rivers
- Palustrine eg Peatlands
Describe the characteristics of Riverine wetlands.
- linked with river systems only
- connected only during high water
- hydrologically separated from the parent water body
- rely on the input of sediments and water during floods for nutrients
E.G. - river Shannon Callows
Describe the characteristics of Lacustrine wetlands
- Continuous hydrological connection with parent water body
- Exchange nutrients with open water body
- Supports communities which are detritus lead (OM)
EG- River Corrib at Corrib village
Describe the characteristics of Palustrine wetlands
-develop in shallow lake basins
-independent hydrology=rainwater
-accumulation of partially decayed organic matter
-water table always at the top or near soil surface
-constantly water logged
EG- Abbeyleix bog Co Laois
What causes a clear decrease in CPOM?
Increasing stream order
What are the four wetland characteristics?
Geomorphology
Hydrology
Hydric soils
Aquatic plants
