Lake%20(limnic)%20ecosystems - PowerPoint PPT Presentation

View by Category
About This Presentation
Title:

Lake%20(limnic)%20ecosystems

Description:

Open lakes have outflow streams. ... 1. All lakes are temporary features of the Erth's landscape ... Perturbations of coastal lakes on Vancouver Island ... – PowerPoint PPT presentation

Number of Views:227
Avg rating:3.0/5.0
Slides: 55
Provided by: IanHutc1
Learn more at: http://www.sfu.ca
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Lake%20(limnic)%20ecosystems


1
Lake (limnic) ecosystems
  • Origins and classifications
  • Lakes as open systems
  • Light and temperature
  • Lake chemistry
  • Primary productivity
  • Secondary productivity
  • Lake evolution
  • Perturbations

2
Lake classification geological origin
  • Lakes result from impoundment of water by
  • tectonic downwarping (e.g. Lake Victoria)
  • tectonic faulting (e.g. Dead Sea)
  • volcanic eruption (e.g. Crater Lake)
  • landslide dams
  • ice dams
  • biotic dams (e.g. Beaver lake)
  • glacial erosion (e.g. Lake Peyto)
  • glacial deposition (e.g. Moraine Lake)
  • river channel abandonment (e.g. Hatzic Lake)
  • deflation

3
Lake classification morphology
  • Lake morphology (size, surface area and depth)
    largely determined by origin.
  • Substrate (rocky, sandy, muddy, organic)
    initially determined by geological origin
    thereafter by inputs.

4
Lake classification hydro-regime
  • Open lakes have outflow streams.
  • Closed lakes are found in endorheic basins in
    arid areas e.g Lake Eyre (Australia) shallow
    lake forms in La Niña years (e.g. 2000), usually
    persists for 1 year. Never overflows - lake sits
    at 15m below sea level.

5
Lakes as open systems
6
Kamloops Lake inflow, water level and residence
time variations
7
Thermal stratification of lakes the physical
properties of water
8
Thermal stratification of temperate lakes
9
Variations in epilimnion depth on windy and calm
days
10
Seasonal temperature profile
11
Lake mixing types
12
Lake mixing types
13
Turbidity, illumination, and the euphotic zone
(--)
14
Kamloops Lake turbidity profile
Thompson R. inflow equilibrium level
15
Kamloops Lake euphotic zone and epilimnion
16
(No Transcript)
17
(No Transcript)
18
Biomass ( lake primary productivity) in
relation toP availability
19
Lake classification trophic status
20
What is the trophic status of Kamloops Lake?
Total P 4 - 10 µg l-1 Total N 150 -250 µg
l-1 Total inorganic solids 60 mg l-1 TN TP
25 -35 Mean primary productivity 88 mgC m-2 d-1
21
Kamloops Lake relative abundance of
phytoplankton groups
22
Kamloops Lake primary productivity
euphotic zone (May)
euphotic zone (Aug.)
23
Energy sources
24
Small temperate lake fodwebs are detritus-based
(e.g. Marion Lake).Predictions for Kamloops
Lake?
25
Lake environment and community structure (North
American boreal lakes)
Environmental Fish
assemblage factor PIKE BASS MUDMINNOW Area large
-------------------- small pH high
-------------------- low Conductivity high
-------------------- low Depth shallow --
deep -- shallow Isolation low
-------------------- high
26
Lake evolution
1. All lakes are temporary features of the Erths
landscape - eventually they fill with organic and
inorganic sediments to become bogs or
playas. 2. The pathway of lake evolution
prior to infilling is a matter of debate. The
classical European literature (1920s -50s)
suggests that lakes progress from oligotrophic to
eutrophic status. Pollution by agricultural
fertilizers, etc. accelerates this process.
27
Lake infilling Cedar Creek, Minnesota
28
Lake evolutionGlacier Bay foreland, AK.
Engstrom et al. (2000) Nature 408 161
29
Stream and lake evolutionGlacier Bay foreland,
AK.
Source Milner et al., 2007, Bioscience, 57,
237-247
30
Perturbations of lake environments
1. GEOLOGICALlocal events such as landslides
regional events such as tephra deposition 2.
CLIMATIC changes in regional climate (precip.
or evap.) 3. ANTHROPOGENIC agricultural/indust
rial/urban pollution 4. BIOTIC invasion by
exotic species (often anthropogenic)
31
Perturbation tephra deposition into Opal Lake,
Yoho NP
Hickman Reasoner (1994) J. Paleolimnology 11,
173-
32
Perturbations of coastal lakes on Vancouver Island
33
Reconstructing perturbations in lake environments
using diatoms as a proxy for lake chemistryI
calibration based on 53 lakes in Ontario
34
II. Case study of anthropogenic pollution of
Little Round Lake, Ontario.
1970
1850
35
Stream (lotic) ecosystems
  • Controls on stream ecosystems
  • Discharge regimes and biotic activity
  • Segment/reach analysis
  • Stream foodwebs
  • The river continuum concept
  • Nutrient cycling
  • Patch stability and dynamics

36
Stream communities
Physical habitat
Biotic community
  • Physical structure
  • Flow dynamics
  • Community organization
  • Community dynamics

Available species pool
37
Stream classification
38
Stream classification
Poff and Ward (1989) Can. J.Fish. Aquat. Sci.
46, 1805.
39
Discharge regimes
Poff and Ward (1989) Can. J.Fish. Aquat. Sci.
46, 1805.
40
Stream segment (reach) classification and analysis
41
Stream foodwebs
allochthonous autochthonous
nutrient sources
functional feeding groups
POM particulate organic matter (C coarse F
fine) DOM dissolved organic matter
42
River continuum concept
  • Continuous physical gradient from headwaters to
    mouth.
  • Consistent biotic patterns of loading, storage
    and utilization of organic matter.
  • Stream communities conform to the mean (most
    probable) state of the physical system.
  • Biotic communities are graded downstream to
    accommodate leakage of organic matter from
    upstream.

Vannote et al. (1980) Can. J.Fish. Aquat. Sci.
37, 130.
43
RCC parameters
44
River continuum concept in application
Vannote et al. (1980) Can. J.Fish. Aquat. Sci.
37, 130.
45
Headwater streams are heterotrophic (P/R ratio
ltlt1) downstream reaches are balanced (P/R ratio
1)
46
Alpine-arctic streams dominantly autotrophic
47
RCC boreal streams
48
RCC deciduous forest streams
49
Stream order, nutrient sources and FFGs
50
Stream nutrient cycling dynamics
51
Stream hierarchy and patch (pool/riffle and
microhabitat) dynamics complex habitats produce
stable communities
52
Pool-riffle sequences and patchy lotic habitats
53
Blackwater rivers terrestrial inputs are not
always beneficial
Kaieteur Falls, Guyana
54
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/Salmo
    n_Bear/
About PowerShow.com