Comparative ecology of the macrofauna of freshwater and marine muds 1

There are many striking similarities between the benthic macrofauna inhabiting marine and lacustrine sediments. Most of the same trophic/functional groups are well represented in both habitats. There is no obvious difference between the types of particulate food sources available for microphagous animals. Temperate lakes and neritic environments support a similar standing stock of macrofauna, which is a function of similar detrital input to the benthos. There is no characteristic difference in P : B ratios between marine and freshwater macrobenthos. Predation and competition have similar important effects on community structure. Likewise, community succession appears to follow the same pattern. There are certain differences between marine and freshwater macrobenthos, however, that appear to relate to fundamental habitat differences. The major difference is that low salinity and the closed, ephemeral nature of most lakes have resulted in little taxonomic similarity between the two faunas. Tentaculate deposit feeders are found only in marine sediments, and interstitial suspension feeders are common only in freshwater muds. The ability to use dissolved organic matter is well developed only in marine animals, which is a consequence of the osmotic problems faced by freshwater animals. The ability of many limnetic species to survive prolonged anoxia relates to the lack of tidal mixing in lakes.