374 J.E. Hobbieetal. 



10' 



10 



10 



\ I0« 



J2 

 o 



3 7 



•2 10 



> 



c 



10' 



10 



zooflagellates 



ciliates 



_L 



20 

 Jun 



10 



20 



Jul 



10 



Aug 



10 



10^ - 



6 



£ 



FIGURE 8-10. Numbers and biomass of zooflagellates, 

 ciliates, and micrometazoa in the sediment of the center of 

 Pond B, 1973. 



In pond B, the small zooflagellates are numerically the most 

 important element of the microfauna; their wet weight per square meter is 

 equalled by the micrometazoans (Figure 8-10). These zooflagellates have 

 only rarely been quantitatively studied in nature (see Fenchel 1970) but 

 they are important bacterial grazers here and undoubtedly in many other 

 aquatic systems as well. Common genera were Manas, Oikomonas, and 

 Bodo. All measure 5 ^ln\ or less in diameter and all graze on bacteria. 



In these detritus-rich sediments, the robust burrowing forms of the 

 micrometazoa, such as nematodes, ostracods, harpacticoids, and 

 turbellarians, are more successful than the ciliates (Figure 8-10), which are 

 more abundant in sandy capillary sediments. Both the numbers and 



