Lake (limnic) ecosystems Origins and classifications


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Lake (limnic) ecosystems


Lake classification: geological origin



Lake classification: morphology



Lake classification: hydro-regime



Lakes as open systems



Kamloops Lake: inflow, water level and residence time variations



Thermal stratification of lakes: the physical properties of water



Thermal stratification of temperate lakes



Variations in epilimnion depth on windy and calm days





Lake mixing types



Lake mixing types



Turbidity, illumination, and the euphotic zone (--)





Kamloops Lake: euphotic zone and epilimnion







Biomass (= lake primary productivity) in relation to P availability



Lake classification: trophic status



What is the trophic status of Kamloops Lake?



Kamloops Lake: relative abundance of phytoplankton groups



Kamloops Lake: primary productivity



Energy sources



Small temperate lake fodwebs are detritus-based (e.g. Marion Lake). Predictions for Kamloops Lake?



Lake environment and community structure (North American boreal lakes)



Lake evolution



Lake infilling: Cedar Creek, Minnesota



Lake evolution: Glacier Bay foreland, AK.





Perturbations of lake environments



Perturbation: tephra deposition into Opal Lake, Yoho NP



Perturbations of coastal lakes on Vancouver Island



Reconstructing perturbations in lake environments using diatoms as a proxy for lake chemistry I: calibration based on 53 lakes in Ontario



II. Case study of anthropogenic pollution of Little Round Lake, Ontario.



Stream (lotic) ecosystems



Stream communities

  • Physical structure

  • Flow dynamics



Stream classification



Stream classification



Discharge regimes



Stream segment (reach) classification and analysis



Stream foodwebs



River continuum concept



RCC parameters



River continuum concept in application



Headwater streams are heterotrophic (P/R ratio <<1); downstream reaches are balanced (P/R ratio ~1)



Alpine-arctic streams: dominantly autotrophic



RCC: boreal streams



RCC: deciduous forest streams



Stream order, nutrient sources and FFG’s



Stream nutrient cycling dynamics



Stream hierarchy and patch (pool/riffle and microhabitat) dynamics: complex habitats produce stable communities



Pool-riffle sequences and patchy lotic habitats



Blackwater rivers: terrestrial inputs are not always beneficial



Marine subsidies in riverine and riparian environments

  • Salmon streams:

  • dead salmon add considerable quantities of marine-derived N (22-73% of total N) to their natal streams.

  • bears and other scavengers drag salmon carcasses into riparian habitats; as a result (in AK-PNW):

  • 15-30% of the N in riparian plant foliage is derived from marine sources; the amount declines with distance from the stream;

  • Sitka spruce grows 3x as fast adjacent to salmon streams but western hemlock shows no response;

  • annual variations in tree growth are significantly correlated with salmon escapements in riparian forests of the Pacific Northwest.

  • Notes derived from:

  • http://www.fish.washington.edu/people/naiman/Salmon_Bear/




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