A new device for studying benthic invertebrate recruitment

An automated larval settlement sampler has been designed and tested in the field to examine the effects of environmental conditions on the recruitment of epifaunal and infaunal benthic invertebrates. The sampler (1) exposes substrates to settling larvae at four discrete levels of naturally varying environmental conditions (e.g. different tidal states, current speeds, light regimes), (2) repeatedly exposes substrates over a period (2–8 weeks) sufficient to accumulate measurable numbers of recruits, and (3) maintains unexposed substrates in an environment that does not result in unnatural levels of mortality. Preliminary field trials indicate that the device was effective in assessing recruitment responses of epifaunal invertebrates to diurnal variations in light level and infaunal invertebrates to variations in tidal state.