Abstract
Despite the importance of sea stars in structuring invertebrate communities, their growth rates remain understudied, largely owing to their mobility, difficulty in identifying individuals, and lack of growth lines or increment bands. We examined growth in the temperate sea star Coscinasterias muricata to determine whether the tetracycline tag-recapture method, commonly applied to other marine invertebrates, is a viable approach for studying their growth in situ. Individuals were chemically tagged in the field and laboratory and resampled from the populations after one year. The mark-recapture data were used to construct a Richards growth curve, which was consistent with the progression of age classes observed in size-structure data collected from the same wild population. C. muricata is a fast-growing animal, reaching 60% of its asymptotic size by age three and 90% by age seven. A decline in growth rate between one and three years of age is consistent with a shift in energy allocation away from somatic growth to energy storage and reproduction. This study represents the first successful application of chemical tag-recapture to a sea star. While a low return rate of tagged animals (18% in the field) was achieved, the viability of the method is established, and with refinement to increase recovery rate, it will provide a useful approach for researchers interested in quantifying sea star growth in situ.