Meiofauna‐Macrofauna Interactions in a High Salt Marsh Habitat

Biological interactions between meiofauna and macroepifauna were studied in a high salt marsh habitat using manipulative techniques. When macroepifauna were excluded from experimental cage sites, meiofauna densities increased significantly compared to open, noncaged areas. Meiobenthic polychaetes and copepods displayed consistent, seasonal increases in abundance inside cages, although their patterns of response were notably different. The dominant meiobenthic copepods, Stenhelia (D.) bifidia, Microarthridion littorale, Enhydrosoma propinquum, and Schizopera knabeni, responded to macroepifauna exclusion by rapidly (within weeks) increasing in density inside cages and, subsequently, crashing to control field levels. Polychaetes, represented mainly by Manayunkia aestuarina, increased more slowly than copepods inside cages, and unlike copepods, showed no signs of density limitation inside macroepifauna—excluded areas. In cage sites reopened to macroepifauna influences, copepod densities decreased to values intermediate between cage and open control areas, while polychaetes were quickly reduced to open field densities. The exclusion of macroepifauna not only produced changes in densities of polychaetes, but also resulted in increased survival of large size classes. My experimental results support the hypothesis that acroepifauna predation/disturbance has an important effect on meiofaunal assemblages, thus providing insight into possible competitive associations between meiofauna taxa. The significance of meiofauna—macrofauna interactions in benthic systems is discussed.