Individual and population level effects of ocean acidification on a predator-prey system with inducible defenses: bryozoan-nudibranch interactions in the Salish Sea
There is an increasing need to understand how ocean acidification (OA) effects on predator-prey interactions propagate from individuals to populations. The calcifying colonial bryozoan (Membranipora membrancea) responds to chemical cues from its specialist nudibranch predator (Corambe steinbergae), by deploying inducible defensive spines. In this study, Seroy & Grünbaum experimentally determined OA effects on bryozoan colony growth and defenses, and developed a spatially explicit model of bryozoan space competition to assess population-level responses. Bryozoans were fairly robust to near-future pH, maintaining inducible defenses at the cost of reduced colony growth. Model results suggest these costs of defense are potentially amplified due to space competition, highlighting the need to integrate population-level processes when assessing responses to OA.