  Although the existence of robust inverted biomass pyramids seem paradoxical,
they have been observed in planktonic communities, and more recently, in
pristine coral reefs. Understanding the underlying mechanisms which produce
inverted biomass pyramids provides new ecological insights, and for coral
reefs, may help mitigate or restore damaged reefs. We present three classes of
predator-prey models which elucidate mechanisms that generate robust inverted
biomass pyramids. The first class of models exploits well-mixing of predators
and prey, the second class has a refuge (with explicit size) for the prey to
hide, and the third class incorporates the immigration of prey. Our models
indicate that inverted biomass pyramids occur when the prey growth rate, prey
carrying capacity, biomass conversion efficiency, the predator life span, or
the immigration rate of prey fish is sufficiently large. In the second class,
we discuss three hypotheses on how refuge size can impact the amount of prey
available to predators. By explicitly incorporating a refuge size, these can
more realistically model predator-prey interactions than refgue models with
implicit refuge size.
