(UJO) lI\l3lMia3S 

 DI90d3V dO Hld3a MV3IAI 



NOTE: The quantity of aerated sediment visible against the thin aquarium 

 wall is expressed as mean depth of aerated sediment, although its distribution 

 is related to burrow location as indicated in Figure 20-3. 



NOTE: Dotted line represents mean depth of aerobic sediment in sediment- 

 filled, thin-walled aquaria in absence of benthic organisms. Mean aerobic sed- 

 iment depth is measured through planimetry of vertical burrowing pattern (e.g. 

 Figure 20-3). 



314 



