Lake (limnic) ecosystems Origins and classifications

Lake (limnic) ecosystems

• Origins and classifications

• Lakes as open systems

• Light and temperature

• Lake chemistry

• Primary productivity

• Secondary productivity

• Lake evolution

• Perturbations

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/