Chapter 27 - Strongylocentrotus franciscanus and Strongylocentrotus purpuratus

Abstract

Abstract Studies of red, Strongylocentrotus franciscanus, and purple sea urchins, Strongylocentrotus purpuratus, have yielded remarkable new discoveries that have advanced sea urchin ecology and biology in multiple fields. Sea urchins are model organisms for the study of developmental biology, as well as ocean warming, ocean acidification and climate change. Research results reveal that larval sea urchins in the plankton can reproduce asexually, change their larval morphology to enhance feeding, recover from months of starvation and disperse over the long distances, connecting populations of benthic adults. Adults living within interconnected metapopulations can utilize dissolved organics when algae are scarce, create rock pits and live for more than 100 years. Sea urchins are best known for their grazing impacts on algal communities. Overgrazing by sea urchins can reduce kelp forests to 'barrens' dominated by coralline algae, but more frequently they coexist in mosaics of algal and invertebrate patches. The spines of red sea urchins form a canopy that shelters juveniles and a suite of species, which, in conjunction with modulating algal resources, makes them ecosystem engineers. Recruitment is highly variable in space and time yet the drivers of recruitment success are poorly understood. Red sea urchins are the basis for important fisheries that lend themselves to spatial management strategies such as Marine Protected Areas. Sea urchins play such an important role in kelp forest communities that the successful management of the community and its ecosystem services will require an integrated ecosystem based approach incorporating what we know about sea urchin ecology.