Biology 3850A Aquatic Ecosystems
Time: Monday/Wednesday/Friday 10:00-10:50 AM,
Jan 06-Apr 16, 2010
Place: B 775
Instructor: Dr. Joseph B. Rasmussen—office hours by appt.
Professor, Department of Biological Sciences
Canada Research Council Chair in Aquatic Ecosystems
Office: WE1050 WESB
Phone: (403) 382-7182
Email: joseph.rasmussen@uleth.ca
Lab Assignments—8% each
I : The watershed and stream dynamics—
II. Morphometry and dynamics of lakes—
III: Primary production: calculation of 1o productivity
IV. Phosphorus loading models and eutrophication
V. Secondary producers: fish productivity and management
Aquatic Ecosystems
Definition of Eco-system
System –many components functionally interacting
most of these components are living organisms
genetically unique and always changing (evolution)
Composed of the biological community (many species populations)
Interacting with the physical world
Aquatic and terrestrial ecosystems are very different in their physical
character and this has a major impact on the way nutrients cycle
as well as on the types of organisms that are found there.
-Key physical processes in aquatic systems—flow and sedimentation (mud)
-flow brings nutrients into the system from the surrounding landscape
(watershed), and cause them to be lost as well.
Next: people who have played a major role in the development of Aquatic
Ecosystem concepts
Stephen Forbes,1887 “The Lake as a Microcosm”
Founder of the Illinois Natural History
Survey
Well known for his work on aquatic insects
and fishes, and for his description of
aquatic food chains in small lakes and
ponds.
His writings stressed the isolated
autonomous character, the separateness
of lakes/ponds from the surrounding
landscape.
The Productivity of Waters and their Nutrient status
August Thienemann
Einar Naumann
Founders of the International Association of Theoretical and Applied Limnology
The thermal structure and energy budget of lakes, the thermocline
Edward Birge and Chancey Juday sampling zooplankton in Lake Mendota, Wisconsin
Trophodynamic processes
Nutrient cycling in lakes
G. Evelyn Hutchinson
Yale University
Charles S. Elton,
•Fluctuations in numbers of animals
•The food pyramid and the trophic web
•also wrote the first book on the ecological
impacts of exotic species invasions
Eugene P. Odum, 1913 - 2002.
Odum is widely considered to be the
“Father” of ecosystem ecology
Pioneered research into the use of
radioactive tracers and dissolved
oxygen cycles to study primary
Daily cycle in dissolved oxygen (flow weighted average) at Pavan study site
production in aquatic ecosystems.
Pavan
Author of
Fundamentals of Ecology, 1953
12.50
12.00
11.50
11.00
Dissolved O2
mg / l
10.50
100% saturation
10.00
9.50
9.00
8.50
8.00
0:00
8AM
2:24
4:48
2PM7:12
9:36
8PM
12:00
Tim e
14:24
2AM19:12
16:48
21:36
8AM
0:00
Cedar Bog Lake
•Ph.D 1941 from the University of Minnesota
•died at age 27 but is still remembered for
“The trophic-dynamic aspect of ecology,
Ecology 23: 399-418)”
from his thesis work on Cedar Bog, Minnesota.
Raymond Lindeman 1915-42
energy flow through the foodweb could
be analyzed by dynamic models
Energetic efficiency of trophic levels
•This paper has since become the foundation for
research on the flow of energy in plant and
animal communities.
Aquatic Ecosystems provide key resources
E.g. fish, waterfowl, rice
Ecosystem services that freshwater ecosystems provide
•Water supply for drinking, agriculture and industry
•Transport
•Water storage
•Hydroelectric power
•Assimilation of pollutants
•Recreation
•Nutrient transport for fisheries
•Ecosystem services are economically valuable services
provided “free” by natural ecosystems. By free we mean
either at no cost or at a cost well below that of a
manufactured substitute. They are hard to place a value on.
Transportation of people and goods
Fouling of beaches by logging operations
Dams and wiers for
hydroelectric power, flood
control, and water
storage.
Waste disposal
Domestic and industrial
Assimilative capacity
The sewage treatment plant downstream from Lethbridge
Agriculture is the biggest water user of all
Recreation
Golf courses are huge water users.
The golf courses are the greenest
part of Lethbridge during the summer