Metabolic depression in sea urchin barrens associated with food deprivation

The proliferation of sea urchins can decimate macroalgal forests in coastal ecosystems, leading to persistent barren seascapes. While kelp forests are among the most productive ecosystems on the planet, productivity in these urchin barrens is dramatically reduced. Moreover, urchins inhabiting these food-depauperate barrens face starvation and many survive in these barrens for years or decades. Urchins in barrens can persist by eating food subsidies from drift algae, pelagic salps, tubeworms, as well as encrusting and filamentous algae, microbial mats, and slow-growing species resistant to herbivory. Despite both food from endogenous production and exogenous subsidies, many urchins in barrens likely experience prolonged food deprivation. This resource limitation may create a trade-off between reproduction and survival; for example, fecundity of purple sea urchins (Strongylocentrotus purpuratus) is 99.9% lower in barrens. Despite food constraints, red sea urchins (Mesocentrotus franciscan...