AEES 2012 STUDENT DESIGN COMPETITION
An Agro-ecological Microcosm
Each year, AEES hosts a student design competition at the society’s annual meeting. The
competition is open to teams of undergraduate and graduate students attending the annual meeting.
Teams generally consist of students from a single university, but may be formed by students from
different universities where necessary to form a critical mass. In response to student feedback from
previous competitions, an effort has been made to reduce the amount of time that must be spent on
the competition during the conference. This means that some of the effort has been shifted to
preparation that must take place prior to the conference. It is strongly suggested that teams get started
on their projects as soon as possible.
INTRODUCTION
One of the primary goals of ecological engineering is the “design of sustainable ecosystems that
integrate human society with its natural environment for the benefit of both (Mitch and Jorgensen,
2004). While the concepts of sustainability have been debated and various definitions exist, all imply
some notion of balance of materials and optimum allocation of matter and energy in hierarchical chains
of transformation and feedback that mutually support the components of the system. While
sustainability on a large scale is difficult to attain because of the myriad inputs and variables of a
complex self-organizing ecosystem, principles of sustainability can be demonstrated and engineered into
ecosystems in miniature. The history of the balanced aquarium concept (Odum and Johnson 1955) is
long, but the concepts persist as a model of sustainability, and the design and construction of a balanced
aquarium is an ideal demonstration of ecological engineering concepts. The intention of this design
project is to replicate the ecological design of a sustainable agroecosystem that includes higher plants
and heterotrophic organisms in balance with each other with the dual function of sustaining the
organisms and having net production of the autotrophs that replicate economically viable crop species.
This system will represent a scaled-down model of an urban aquaponic system, which could be used to
produce food in areas with limited access to open land.
THE CHALLENGE
The challenge of the design competition is for teams to demonstrate the principles of ecological
engineering by constructing a balanced, closed aquatic microcosm that maximizes productivity and
provides for the welfare of a crayfish. Teams must design and construct a CLOSED, ten gallon aquatic
microcosm that will meet the following goals:
1. Maintain adequate water quality to keep one crayfish alive;
2. Maximize primary production of the autotrophic component, with emphasis on edible plant
species;
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3. Demonstrate the system’s sustainability through calculation of an Emergy Sustainability Index
(ESI);
To do this, teams must use ecological design principles to establish a microcosm that balanced for
material flows and driven primarily by solar energy. Material closure implies that the metabolic needs of
the individual organisms and their functional groups will be supplied by the balance of biogeochemical
cycles within the closed ecosystem.
MICROCOSM COMPETITION
At the beginning of the conference, student groups will receive materials and will assemble their
microcosms. These microcosms will be monitored for the duration of the conference, until the award
ceremony.
The following materials will be provided to the students upon arrival and coordination with the student
design competition committee:
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One 10-gallon aquarium with gravel
One crayfish
Materials to seal system
o Plexiglass cover
o Waterproof tape
o Tubing to create sampling port
Testing supplies
o Ammonia test strips
o Dissolved oxygen sensor
o Total Dissolved Solids (TDS) sensor
o Turbidity meter
Teams are expected to add vegetation to the system, which may be brought to the conference or
foraged locally. Students must designate at least one of their vegetation species as a “crop” species to
represent food production. Students may bring any other materials they would like to use, including
pumps, meters, plastic castles, etc. Students travelling internationally or others who may have difficulty
in transporting plants to the conference should coordinate with the student design competition
committee to make alternative arrangements. Microcosms will be housed in a greenhouse on campus.
Lights will not be provided, but electrical outlets are available. The microcosm design may include a
terrestrial component, provided that the aquatic component provides adequate habitat for the crayfish.
The entire system must be contained within the ten gallon aquarium. Upon assembly, microcosms will
be sealed and monitoring will commence. All microcosms will be sealed by 9 PM of the first day of the
conference. Water quality parameters will be monitored by sampling water siphoned from the aquarium
into an external vessel via a capillary tube. Sampling protocols and equipment will be provided.
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MONITORING
Team members will monitor the water quality in the microcosms periodically throughout the duration of
closure. Teams must perform water quality measurements at least four different times throughout the
duration of microcosm closure. A sign-up sheet will be provided for teams to sign up for monitoring
time slots. Monitoring results will be reported using a Google Docs spreadsheet, which will be made
available to all teams and judges. Unannounced sampling by competition judges or their representatives
will occur periodically to ensure the welfare of the crayfish and other organisms in the microcosms.
Microcosms found critically deficient and threatening to the welfare of the crayfish will be immediately
opened by the judges or their representatives.
JUDGING
Microcosms will be judged at the award ceremony on Friday night. Students should be prepared
to answer questions from the judges, which may include questions on the following topics:
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the rationale behind the microcosm design;
a description of the biogeochemical cycling which is expected to occur within the microcosm,
and how this cycling maintains fluxes of important metabolic constituents (oxygen, carbon,
nitrogen) at levels necessary for survival of the crayfish; and
how the system might be scaled up for urban food production;
Fifty percent of the total team score is based on ecological engineering design principles, including:
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Completeness of the design and analysis;
Feasibility of the design; and
Design sustainability.
Fifty percent of the total team score is based on the performance of the microcosm, to include the
following:
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Maintenance of water quality throughout time, especially with respect to turbidity, dissolved
oxygen, and ammonia;
Survival of organisms in the microcosm during closure.
Extra credit may be awarded for especially creative or aesthetically pleasing execution.
Water quality parameters will be judged on 4-point scale (excellent, good, fair, poor). Note that
fluctuation of one or more of the water quality parameters beyond the threshold of mortality for the
organisms that necessitates immediate opening of the closed microcosm will result in a score penalty to
be assessed to the team.
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QUESTIONS
Please feel free to contact the coordinators of the student design competition, Dr. Emily Ayers
(emilymitchellayers@gmail.com) and Dr. David Blersch (dblersch@buffalo.edu) with any questions that
arise.
REFERENCES
Mitsch, W.J. and S. Jorgensen. 2004. Ecological Engineering and Ecosystem Restoration. John Wiley and
Sons, Inc., Hoboken, New Jersey.
Odum, H.T. and J. Johnson. 1955. Silver Springs and the balanced aquarium controversy. Science
Counselor 15:128-130.
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