Refuges from Fish Predation: Experiments with Phytal Meiofauna from the New Zealand Rocky Intertidal

Phytal meiofauna are numerically important members of rocky intertidal communities and known to be prey items for various small fishes. In a series of experiments we demonstrated that substrate complexity is an important factor in reducing predation. The alga Carollina officinalis, the most complex structure used, was the only refuge from blenny (Helcogramma medium) predation for total meiofauna, and the dominant taxon, copepods. This refuge effect was evident whether the prey fauna were originally from Corallina or from another alga. One harpacticoid copepod species (Amphiascus lobatus) was selectively preyed upon, with females preferentially taken over males. Our results and those from the literature suggest that fish predation on benthic invertebrates may not be linearly related to decreasing substrate complexity. Rather there appears to be a complexity threshold below which removal rate is not significantly affected by structure and above which removal rate is significantly reduced.