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 Wisconsin- Milwaukee Great Lakes WATER Institute Dr. Russell Cuhel Senior Scientist

EACH ARROW COSTS 80-90% IN ENERGY NOT ALL ARE SHOWN CUHEL-AGUILAR 2013

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: SEA LAMPREY X CUHEL-AGUILAR 2013

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

ADD: ALEWIFE X X CUHEL-AGUILAR 2013

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 JASON- APPROVED WEBSITE: CUHEL-AGUILAR 2013: NOSB