Meiobenthic interactions with macrobenthic larvae and juveniles: an experimental assessment of the meiofaunal bottleneck

Abstract

The meiofaunal bottleneck hypothesis states that permanent meiofauna (e.g. nematodes, copepods, foraminifera) negatively affect macrofaunal larval settlement and juvenile survivorship. Field studies suggest enhanced meiofaunal densities decrease recruitment of some macrofauna but do not identify whether thls IS a settlement or post-settlement process. Our experiments specifically examined the settlement response of the spionid polychaete Streblospio bened~cti Webster and the venerid bivalve Mercenana n~ercenaria (L.) to functionally different meiofaunal taxa (burrower, epibenthic, sediment sweeper). ANOVA revealed no significant effect of any meiofaunal taxon on macrofaunal settlement. Further experiments on emigration of recently-settled (<24 h old) juvenile S. benedicti and M. rnercenana showed no difference in burial times (time from initial juvenile contact with the sediment surface until complete burial below the sediment surface) between meiofaunal treatments and control sediments. Our data suggest that if the meiofaunal bottleneck exists, it is not a settlement phenomenon nor does it cause emigration of these recently-settled macrofauna.