160 The UMAP Journal 30.2 (2009) less compatible counterparts. Developing methods that are both cost-effective and have a low impact on the surrounding ecosystem is an important issue and a complex and timely challenge. A common method is simply to raise one species of carnivorous fish pens set directly in coastal waters. Unfortunately, this method causes several environmental problems There is no real barrier between the captive and wild populations, so any disease that occurs in the densely packed pens will flow directly into contact with wild populations No filtration ofeffluentexists-allexcess feed, fish feces, and microbial pop- ulations mix directly with natural waters Living organisms can only use 10-20% of the energy they consume, so the other 80-90% goes to waste-raising an organism higher up the food chain (a carnivore)means that several rounds of 80-90%loss occurred to simply make the food that the target species will eat. These practices are currently happening on and adjacent tomany coralreefs a growing body of scientific literature is demonstrating that these fish farms have a significantnegative impact on the corals, and thus major improvements are needed to attain a viable industry and a sustainable coral reef ecosystem Formulation and intent of the problem The goal of this years ICM problem was for student teams to tackle ecological and technological challenges of improving such practices within actable confines of one specific case study of milkfish( Chanos chanos)aqua culture directly next to coral reefs in Boliano, Philippines. There are many possible approaches to improving the current situation, but we asked teams specifically to come up with a polyculture scenario that would improve water quality sufficiently for corals to recolonize the areas close to the fish pens where they currently cannot survive. By adding more than one species to the indus- try, energy inputs can be reduced by growing food for the milkfish locally and water quality can be improved by filter feeders and algae that absorb excess nutrients without requiring major gear or technology shifts. This particular method of more environmentally responsible aquaculture also emphasizes the ecological links between different species and trophic levels. There are anum ber of potentially negative impacts associated with introducing new species into an ecosystem, so teams were also asked to evaluate the potential risks Teams were first asked to model the original, healthy coral reef ecosystem before theintroduction of fishfarms. For the purpose of modeling, the complex tem was si lified to one member from each major trophic and phylo genetic guild. The purpose was to identify how thenatural systems organisms interact to control water quality in the area160 The UMAP Journal 30.2 (2009) less compatible counterparts. Developing methods that are both cost-effective and have a low impact on the surrounding ecosystem is an important issue and a complex and timely challenge. A common method is simply to raise one species of carnivorous fishin pens set directlyin coastal waters. Unfortunately, this method causes several environmental problems: "* There is no real barrier between the captive and wild populations, so any disease that occurs in the densely packed pens will flow directly into contact with wild populations. "* No filtration of effluent exists-all excess feed, fish feces, and microbial pop￾ulations mix directly with natural waters. "* Living organisms can only use 10-20% of the energy they consume, so the other 80-90% goes to waste-raising an organism higher up the food chain (a carnivore) means that several rounds of 80-90% loss occurred to simply make the food that the target species will eat. Thesepractices are currentlyhappening on and adjacentto many coralreefs. A growing body of scientific literature is demonstrating that these fish farms have a significant negative impact on the corals, and thus major improvements are needed to attain a viable industry and a sustainable coral reef ecosystem. Formulation and Intent of the Problem The goal of this year's ICM problem was for student teams to tackle the ecological and technological challenges of improving such practices within the tractable confines of one specific case study of milkfish (Chanos chanos) aqua￾culture directly next to coral reefs in Boliano, Philippines. There are many possible approaches to improving the current situation, but we asked teams specifically to come up with a polyculture scenario that would improve water quality sufficiently for corals to recolonize the areas close to the fish pens where they currently cannot survive. By adding more than one species to the indus￾try, energy inputs can be reduced by growing food for the milkfish locally and water quality can be improved by filter feeders and algae that absorb excess nutrients without requiring major gear or technology shifts. This particular method of more environmentally responsible aquaculture also emphasizes the ecological links between different species and trophic levels. There are a num￾ber of potentially negative impacts associated with introducing new species into an ecosystem, so teams were also asked to evaluate the potential risks associated with their polyculture solution. Teams were first asked to model the original, healthy coral reef ecosystem before the introduction of fishfarms. For the purpose of modeling, the complex ecosystem was simplified to one member from each major trophic and phylo￾genetic guild. The purpose was to identifyhow the natural system's organisms interact to control water quality in the area