Aquatic Biomes, Continued

Aquatic Biomes, Continued
Introduction
Extent of Marine biomes
Issues & challenges
Factors influencing distribution
Dynamics in time & space
Depth
Tour of marine biomes
Issues (by biome)
Freshwater biomes
Factors
Issues
Biome tour
Molles & Cahill 2008
Readings:
Today – Chapter 3
Friday – see links posted on Website: http://www.biology.ualberta.ca/courses.hp/bio208/
Distribution of Water in the Biosphere
<3%
Mackenzie 2003
Temperature salinity, and nutrients (affected by currents) influence the
distribution of marine organisms. Light penetration (depth) are also important.
“pelagic”
“benthic” = bottom
“abyssal”
Fig. 3.6
Molles & Cahill, 2008
Coastal Biomes – Kelp “forests” and coral reefs
Fig. 3.14, Molles & Cahill 2008
Coral reef – tropics
Kelp forests
- Colder latitudes
Figs 3.11 & 3.16 – Molles & Cahill 2008
Intertidal region – zone between low and high tide
Fig. 3.19 - Molles & Cahill, 2008
Intertidal organisms are adapted to extremes
(physical forces, temperature extremes, dessication)
Molles 2008
Sea stars, mussels and anemones in the rocky intertidal
The rocky intertidal has been
the subject of many classical
studies in community
ecology (e.g. work of Paine
and colleagues on “keystone
species”).
Fig. 3.18, Molles & Cahill 2008
Coastal biomes – salt marshes and mangrove forests
Note the distribution by latitude
Fig. 3.24, Molles & Cahill 2008
Coastal Biomes Represent Transition Zones
(between freshwater & saltwater)
Fig. 3-28
Molles & Cahill
Salt marshes dominate coastlines in cool regions
Molles
2008
Molles & Cahill
2008
Aerial view of a salt marsh – note the gradual transition between land and sea
Fig. 3.25, Molles & Cahill 2008
Mangroves dominate coastlines in warm (tropical) regions
Fig. 3.23
Fig. 3.27
Molles & Cahill2008
The importance of Coastal Zones:
“Buffering” by kelp forests, coral reefs, salt marshes, mangrove forests,
and other near-shore ecosystems protect coastal communities.
Human alteration of coastal zones disrupts these buffering processes.
(Alterations include development, destruction, pollution, altered runoff…)
Heywood, Global Biodiversity Strategy
Alteration of coastal habitat
60% of human population
lives within 100 km of the
coast (Vitousek et al. 1997)
http://gallery.marinephotobank.org/
Dredging and filling of salt marshes
Fig. 3.29, Molles & Cahill
Earthquake Spawns Tsunami
Jan. 3, 2003
High-resolution images: Khao Lak, Thailand
Dec. 29, 2004
Wave ~ 10m
IKONOS
Coastal areas with healthy mangrove forests had significantly less
loss of life than areas where mangrove forests had been removed.
Arctic sea ice – a shrinking marine biome
The extent of “permanent ice”
is changing rapidly.
Stroeve et al. 2008
…sometimes leaving marine mammals stranded.
Freshwater biomes
(Rivers, Lakes, & Wetlands)
Human changes to freshwater biomes:
• Humans now divert 50% of the planet’s freshwater supply
(70% of this is used for agriculture) - Vitousek et al. 1986, 1994, 1997
• Altered structure and flow regimes alter aquatic communities.
China’s Three Gorges Dam - http://en.wikipedia.org/wiki/Three_Gorges_Dam#Project_history
Factors affecting productivity and distribution of organisms in freshwater biomes:
Temperature
Nutrient levels (N, P, …)
Remember Schindler’s
Lake Experiments:
Oligotrophic  Eutrophic
Oxygen (O2)
Salinity (esp. desert water bodies)
pH (e.g. bogs)
Fig. 1.5, Molles & Cahill 2008
Distribution of major lakes
Fig. 3.39, Molles & Cahill 2008
Lake Structure
“photic” zone (epilimnion)
Benthic region
Temperature stratification & periodic lake mixing
Many temperate lakes
have two periods of
mixing (spring & fall)
Lake mixing brings
nutrients to the photic zone,
causing periodic bursts of
productivity.
Fig. 3.41, Molles & Cahill 2008
Rivers & Streams
Fig. 3.31, Molles & Cahill 2008
“Stream order” – a system of classification (Strahler 1952)
Variation in biological communities
along the “river continuum”
Course Particulate
Organic Matter (CPOM)
Fine Particulate
Organic Matter (FPOM)
Fig. 3.37, Molles & Cahill 2008
Many streams are dynamic, and many organisms are adapted to disturbance
Streams influence surrounding communities (“riparian zone”)
Fig. 3.32, Molles & Cahill
Note differing flow regimes in streams from wet and dry climates
Fig. 3.34
Flow regimes are
further affected by
human alteration
(dams, irrigation,
etc.)
Fig. 3.35, Molles & Cahill 2008
Wetlands (including bogs & fens)
Fig. 3.45, Molles & Cahill 2008
Arctic Tundra (Alaska’s North Slope)
Satellite image of Northern Alaska
C. Tweedie
Note how many northern (boreal and
tundra) regions are filled with wetlands.
J. Gamon
Bogs & Fens – two common wetlands in Canada
Bog – stagnant water
Cold, low pH, nutrient-poor
( low decomposition rates)
Fen – has some water flow
Fig. 3.46, Molles & Cahill 2008
Note how soil carbon patterns match global wetland distribution
Northern warming releases soil carbon stored
over millenia – will this affect the climate?
http://earthtrends.wri.org/text/climate-atmosphere/map-226.html