biome · lake bioengine — grow the protein in the sewage plant

The terrestrial web asks does the loop close?. The lake asks a sharper, dual-purpose question: can one body of water be both the crew's fish farm and its water-treatment plant? In a closed cylinder the cheapest design makes them the same ecosystem — the fish you eat are grown on the nutrients you'd otherwise strip out with hardware (Todd's eco-machines; integrated poly-culture; constructed treatment wetlands). Two figures of merit: surplus harvestable fish and effective water treatment. Every species is picked for its role in those. Same element-exact engine — carbon/oxygen/water/nitrogen conserve to machine precision.  → build your own · terrestrial web · global web · stability lab

Knobs

Water quality & food supply over ~600 days

dissolved N (mmol/L) organic load (mol C/L) O₂ (kPa) calorie supply ÷ demand fish yield (kg/day)

The lake food web — populations (each scaled to its own peak)

phytoplankton duckweed water fleas mussels benthic detritivores tilapia

The roster — each species earns its place

OrganismRole in the two figures of meritYield tap