Growth, fecundity, and reproductive biology in the pedunculate cirripede Pollicipes polymerus at San Juan Island, Washington

Abstract

Four populations of Pollicipes polymerus were sampled monthly for 26 months at two localities and two intertidal levels at San Juan Island, Washington, to determine the breeding season near the northern limit of the distribution of the species and for the comparison of growth, breeding cycles, and fecundity between the four populations.Pollicipes polymerus may reach a rostral–carinal length of 17 mm and sexual maturity during its 1st year after settlement. Subsequently, growth rate is reduced to about 2 mm in rostral–carinal length per year. The mean adult size increases from high intertidal level, Edward's Reef to low intertidal level, Edward's Reef to high intertidal level, Eagle Point to low intertidal level, Eagle Point. Juvenile growth rates, the percentage of breeding adults in an average month, and the mean monthly egg production also followed the above trend. Pollicipes polymerus breeds from late April through early October with a peak in July. The breeding season of the population at Eagle Point is longer than that of Edward's Reef. Obvious environmental factors that may have some effects on fecundity, growth rate, and the breeding season include temperature, wave action, food supply, and salinity. Preferred conditions include heavy surf and oceanic salinity.