Test 4 Flashcards
What are the 8 key physical and chemical properties of fresh water systems?
- Density, viscosity
- Flow, velocity and depth
- Light
- Temperature
- Dissolved Oxygen
- Carbon Dioxide
- pH
- Nutrients
how does density vary?
Through salinity and temperature
Viscosity (resistance of fluid to sheer stress) – what does roughness increase with?
Size and velocity
Does Flow/discharge increase or decrease down stream?
Increase due to direct runoff
What are lotic and lentic systems?
Rivers – flowing systems – lotic
Lakes – standing systems – lentic
What is water temp dependant on?
o Origin: ground water, surface runoff, glaciers o Tributary inputs o Air temperature o Season o Time of day o Water depth and discharge o Substrate and amount of turbulence
why does water have less variable temp to air
has a lower specific heat capacity
2 types of ice on rivers
Frazil, mobile ice at start, Anchor, connected to banks and doesn’t move
Name two rivers with long term trends
Mississippi - mean water increase from 1.6 to 2.2 degrees due to industrial influence
Trent - decline in water temp due to shut down of coal mines along river
Species and temperature rate effects - use examples
Salmon and Mayfly - Speed of mayfly development depends on time of year as temp of water
What happens with an increase and decrease in dissolved oxygen
Increase - More oxygen = more plants in river
Cold water can hold more oxygen than warm
Decrease - Respiration, overall mainly decomposers organisms like algae
which altitude can water hold more oxygen
Lower altitudes
What is the pH of natural rainwater, lake or river
- 64
4. 5 - much less
7 essential plant growth nutrients
Calcium iron manganese Magnesium Potassium Silica Sodium
What is nitrogen for streams and rivers
In flux with the atmosphere as well as cycling within the system
What globally is the limiting element + give more
Phosphorous
N:P >16:1 P is limiting
Pollution affects with N and P
Pollution just N not significant effect but with P can result in detrimental rapid plant growth
What is allochthonous carbon
Organic carbon originating outside stream - e.g. leaves and twigs
What is autochthonous carbon
Organic carbon originating from the stream e.g. diatoms growing on surface stones
What’s the difference between hemimetabolies and metamorphosis
hemimetabolies = Eggs -> insect nymph -> adult
Complete metamorphosis = Eggs -> insect larvae -> pupae -> adult
meta - very obvs differences
Name the 5 feeding groups
Shredders - utilize CPOM create FPOM
Collectors - gathers - collect organic matter from bed Collectors - filterers - filter FPOM from water column
Scrapers - scrape attached algae from stones
Predators - eat the other invertebrates
Give the 4 main stages of leaves that fall into rivers
- Leaching - 15-25% in first 24 hours
- conditioning - colonisation by fungi then bacteria 7% loss in ~30 days
- invertebrate shredding - 20% breakdown
- physical abrasion
what is RCC
River Continuum Concept
RCC - Headwaters - stream <6m width
- Dominated by shredders
- P/R < 1
- Few scrappers due to low light
RCC - Middle - Stream 6 - 75m width
- Scrappers large component as more light penetration
- collectors also dominant
shredders low number due to little leaf retention - P/R > 1
RCC - Large - widths 75-700m
- Dominated by collectors, gathering and filtering organic
- Scrappers not represented due to depth limiting productivity
- No shredders
- P/R < 1
RCC criticisms
Developed for pristine systems
- interrupted by lots of different things
e. g. dams, urban areas …
What is DIC
Dissolved inorganic carbon
e.g. CO2
What is DOC
Dissolved Organic Carbon
e.g. organic material that can pass through filter
PIC/POC
Particulate (In) Organic Carbon
- similar to DOC but cant pass through filter
What nutrients are limiting in spiralling
C, P, N as undergo extensive utilization as pass downstream
How far does inorganic and organic material travel
90% = inorganic 10% = time spent for organic
What are the components of a nutrient cycle
Spiral length - uptake length + turnover length
Uptake length - average distance travelled
Factors influencing nutrient uptake
- Biochemical (biota doing uptake)
2. Geomorphic (physical properties of channel)
why does biological uptake rates vary as a function of nutrient concentrations
saturation occurs at high concentrations
What does geomorphic retention of nutrirents depends on
- hydrology
- size of particle
- heterogeneity of stream bed
- LWD
- also depends on tightness of spirals and efficiently of stream
What happens when high demand for nutrient spiralling
lengths of spiral increase with discharge
What are the Lake types
- Tectonic
- Volcanic crater
- Meteorite crater
- Thermokarst
- Landslide
- Glacial
- Oxbow
- Manmade
What is retention time
Volume / mean rate of inflow OR mean rate of outflow + plus evaporation rate
Tectonic lakes
includes some of the largest lakes
VERY VERY deep
- Lake Baikal Siberia - oldest lake in the world and is 636km deep
Glacial Lakes
Formed last ice age
Corries
often smaller scale
Man-made
Hydropower
- river water widely fluctuating
Water supply / flood storage
- water stored during winter for summer supply
Why is depth so important in lakes
As influenced by light penetration and temperature regime
Why is autochthonous production important
macrophytes and benthic algae in the margins
phytoplankton in open water
What are the three layers that result from seasonal Summer warming
Epilimnion - upper, warmer, surface layer
Hypolimnion - Deeper, cooler, lower layer
Thermocline - distinct separation
when does the nutrient cycling occur
Spring and autumn when similar temp all down lake depth
Epilimnion - why well oxygenated
Wave action to mix
photosynthesis by phytoplankton
Hypolimnion - oxygen depleted
separated from air
low light penetration
bacterial respiration
Define
- holomictic
- Monomictic
- Warm Monomictic
- Dimictic lakes
- Meromictic
H - mix completely all year M - mix once per year WM - stratify in summer, mixed in winter DM - stratify in both winter and summer, mixing in autumn and spring M - never mix
What are the limiting factors
Nutrients - N and P
Light - transparency determines depth of light penetration
How does energy flow through lakes
Green algae -> herbivore -> carnivore 1 -> carnivore 2 as deeper you go
2 types of sampling in lakes
van dorn - collecting samples
Secchi disc for transparency
what are oligotrophic lakes
- Nutrient-poor
- Low productivity
- High transparency in the epilimnion
- High dissolved oxygen in the hypolimnion
Mesotrophic lakes
Middle of other two tropic lakes
Eutrophic lakes
- Nutrient-rich
- High productivity
- Low transparency in the epilimnion
- Low dissolved oxygen in the hypolimnion
Name producers, consumers, predators, high predators
Pro - Phytoplankton
Con - graving invertebrates
Pred - invertebrates and fish
HP - fish, birds and mammals
Name 7 adaptations
breathing tubes long legs plastron haemoglobin - type pigment gills buoyancy being extremely hyaline (transparent)
Seasonal patterns of phytoplankton
winter - lake is well mixed but plankton abundance low, limited by light and temp
spring - plankton increase and use nutrients
Autumn - first storms = mixing plankton exploit new nutrients
what is the littoral and profundal zone
L - lake bed where plants can grow
P - lake bed where there is no plant growth
what is productivity related to
light
what is limited by O2
benthic communities
Where is the most diversity found
the top of the lake - however not complete top as too much disturbance
