POTENTIAL EFFECT OF ENCLOSURE SIZE ON FIELD EXPERIMENTS WITH HERBIVOROUS INTERTIDAL GASTROPODS

Many experimental studies on the ecology of benthic marine herbivores, particularly those on intra- and inter-specific competition, have use d enclosures to manipulate animal densities. We examined a potential p roblem in the interpretation of these experiments, i.e. the effects of different enclosure sizes on mortality and body weights of a rocky in tertidal limpet fenced at natural densities. There was no mortality du ring the experiment but body weights of limpets were significantly dif ferent between fence sizes varying 4-fold. Interpretations of enclosur e experiments generally, and comparisons of the magnitude of treatment effects in competition experiments specifically, may be equivocal if enclosure sizes are different.