THE FOOD WEB INVADERS GAME
(OR, A DAY JOB FOR SOME OF US!)
FOLLOWING IS OUR QUICK CONSTRUCTION OF A SIMPLE PHOTO
FOOD WEB (NOT FOOD CHAIN!) AS OCCURS IN LAKE MICHIGAN.
ON THE FIRST PAGE ARE ORGANISMS OF THE FOOD WEB, WITH
ONLY ONE OR TWO ORGANISMS PER TROPHIC LEVEL DEPICTED.
IT IS TO GET THE IDEA. THEN, YOU THINK ABOUT A CHANGE,
AND FOLLOW ITS LIKELY CONSEQUENCES AMONG THE
INHABITANTS.
CLUSTERS OF ORGANISMS REPRESENTING A TROPHIC LEVEL
(PRIMARY PRODUCERS, MICROZOOPLANKTON, TOP PREDATORS,
ETC.) ARE CONNECTED BY ARROWS POINTING FROM THE FOOD
TO THE CONSUMER (BOTTOM WORMS ARE EATEN BY PERCH, FOR
EXAMPLE). SOME ARROWS ARE MISSING, OF COURSE.
TO "PLAY" CHOOSE AN INVASIVE ORGANISM FROM TABLE 1,
ASSESS ITS POSITION IN THE FOOD WEB, AND THEN INCREASE
(CONSUMERS) OR DECREASE (PREY) SURROUNDING GROUPS AS
APPROPRIATE.
CUHEL-AGUILAR 2013: NOSB
CHANGING AN AQUATIC
FOOD WEB FROM THE
INSIDE OUT!
Dr. Carmen Aguilar,
Associate Scientist
University of WisconsinMilwaukee Great Lakes
WATER Institute
Dr. Russell Cuhel
Senior Scientist
EACH ARROW COSTS
80-90% IN ENERGY
NOT ALL ARE SHOWN
© Wim van Egmond 1999
the rotifer Euchlanis
CUHEL-AGUILAR 2013
http://www.boois.com/walleye1
Chironomids: Midge Fly larvae (mud dwelling)
REMEMBER THAT NOT EVERY NEW THING WIPES OUT ALL THE
OLD THINGS. SOMETIMES THEY JUST COMPETE, WITH A
NUMERICALLY PROPORTIONAL EFFECT ON FOOD WEB
FUNCTION. THIS IS EXEMPLIFIED BY THE SPINY AND
FISHHOOK WATER FLEAS AND MANY OF THE SALMON FAMILY.
OR, THEY MAY HAVE A DISTINCT EFFECT, LIKE ALEWIFE
OR, THEY MAY BE "DEVASTATING"
BY STUDYING EACH OF THE INVADERS WELL, YOU CAN PUT A
REASONABLE OUTCOME ON THEIR IMPACT.
WHICH INVADERS DID NOT SUCCEED AT ALL?
CUHEL-AGUILAR 2013: NOSB
WE'VE GIVEN 2 EXAMPLES.
FIRST - ADD SEA LAMPREY. WHAT DOES IT "EAT"?
LAKE TROUT, WHITEFISH, OTHER LARGE FISH
WHAT EATS IT?
NOT MUCH THAT WE KNOW OF.
HOW MUCH IMPACT DID IT HAVE?
MEGA: WIPED OUT LAKE TROUT (RED "X")
WHAT ARE THE "DOWNSTREAM" EFFECTS?
RELIEF OF PREDATION ON FORAGE FISH (GREEN)
OPENING NICHE FOR ALEWIFE ESTABLISHMENT (GREEN)
LOSS OF LARGER, MOSTLY ZOO-PLANKTON (RED)
GROWTH OF CLADOPHORA
CUHEL-AGUILAR 2013: NOSB
ADD:
CUHEL-AGUILAR 2013
© Wim van Egmond 1999
Chironomids: Midge Fly larvae (mud dwelling)
SEA LAMPREY
the rotifer Euchlanis
X
http://www.boois.com/walleye1
SECOND EXAMPLE: A RESULT OF THE FIRST…
- ADD ALEWIFE. WHAT DO THEY EAT?
LARGER PLANKTON, BOTTOM INVERTEBRATES
WHAT EATS IT?
SOME MIDDLE FISH (PERCH), PISCIVORES, BIRDS
HOW MUCH IMPACT DID IT HAVE?
MEGA: GREW TO OBNOXIOUS POPULATION LEVELS
LAMPREY HAD REMOVED ITS PREDATOR
WHAT ARE THE "DOWNSTREAM" EFFECTS?
GREATER COMPETITION AMONG FORAGE FISH
OPENING NICHE FOR NEW TOP PREDATOR FISH
LOSS OF LARGER, MOSTLY ZOO-PLANKTON
CUHEL-AGUILAR 2013: NOSB
X
ADD:
X
© Wim van Egmond 1999
ALEWIFE
the rotifer Euchlanis
CUHEL-AGUILAR 2013
http://www.boois.com/walleye1
Chironomids: Midge Fly larvae (mud dwelling)
CONTINUE WITH OTHERS. REMEMBER THAT BEFORE
LAMPREY, FORAGE FISH EXISTED - THAT IS, LAKE TROUT
DID NOT GRAZE FORAGE FISH TO EXTINCTION
PREDATORY WATER FLEAS COMPETE WITH LONG
ESTABLISHED NATIVES LIKE LEPTODORA SP. NONE HAD
OVERWHELMING DOMINANCE
RECENT INVADERS LIKE THE BLOOD MYSID MAY HAVE
VIRTUALLY NO IMPACT ON THE NATIVE MYSID
(OPOSSUM SHRIMP), EVEN THOUGH THEIR POPULATIONS
ARE BECOMING ABUNDANT.
PONDER THE WHYS AND WHEREFORES OF THE VARIOUS
COMPETITION OUTCOMES. GO CHECK OUT THE INVADER
COMPETITION GAME "ECODEFENDERS" ON THE JASONAPPROVED WEBSITE:
www.filamentgames.com/projects/eco-defenders
CUHEL-AGUILAR 2013: NOSB