Determination of the distribution and abundance of the limpet Scurria scurra on the stipes of the kelp Lessonia nigrescens in Central Chile

Abstract

In Central Chile, the limpet Scurria scurra lives in open cavities on the stipes of the kelp Lessonia nigrescens. Several characters in this association, including number of limpets per cavity and number and position of cavities along the stipes, are highly fixed. In thls study we use explanations suggested elsewhere for equivalent specific patterns in other limpet-kelp associations as testable hypothesis for the Scurria-Lessonia relationship. Results indicate that the limpet has a highly predictable location in the kelp bed, decreasing in abundance with decreasing tide levels and with increasing time exposed to waves. Usually one limpet is found per scar and only one scar per stipe, generally excavated under the first stipe bifurcation. Limpets can wander out of the cavities during high tides. They show no significant ontogenic changes in radular structure or in excavating capacities. They could occupy any new suitable stipe once they are dislodged due to accidents while wandering out of the cavity or because of stipe breakage. In addtion, close to 20 % of the limpet population survives stipe breakage by remaining attached to the stipe stumps. Field experiments indicate that friction between the stipes of L. nigrescens is the most important factor determining the number and distribution of cavities on the stipes. A comparison of our findings with results on other limpet-kelp associations indicate that generalizations are restricted to a few common features only. In each association there are several additional specific characters which seemingly represent the outcome of specific life hstory adjustments of each interacting partner.