Rates of fission in Aquilonastra corallicola Marsh (Echinodermata: Asteroidea) as affected by population density

Abstract

The sea star Aquilonastra corallicola reproduces asexually by splitting across the central disc, a process known as fission. Although photoperiod and body mass are known to influence the rate of reproduction in fissiparous asteroid species, to our knowledge, the effects of population density have not been experimentally measured in asteroids. We tested the effects of three population densities on the rate of fission in laboratory populations maintained for 4 months at low, medium, and high (n=5, 15, and 30 per treatment replicate, respectively) population densities. Our results show that population density has a significant, inverse effect upon rate of reproduction in this species. This suggests that density-dependent regulation of asexual reproduction is a significant factor in explaining the observed patterns of population structure in marine clonal invertebrates. © 2011 Taylor & Francis.