Crabby Consequences of an Invasive Seaweed Cuisine: the scoop on Poop, Mass, and Molting in Pugettia gracilis

Abstract

Along the western coast of North America, kelp forests contribute greatly to the productivity of marine ecosystems and are essential to maintain biodiversity (Springer et al., 2010). Throughout their geographic range, bull kelp forests house a variety of fi sh and invertebrates, and provide nursing and nesting grounds for shorebirds and sea otters (Springer et al., 2010). However, deleterious abiotic and biotic forces are threatening these bull kelp forest dynamics. Among those threats, climate change continues to cause increasing shifts in the density and distribution of bull kelp (Beas‐Luna et al., 2020). Frequent marine heatwaves, ocean acidifi cation, and the reduction of trophic regulators such as sunfl ower stars, are threatening bull kelp numbers (Arafeh-Dalmau et al., 2023). In Northern California, more than 90% of kelp forests have been lost due to these marine heatwaves and overgrazing by sea urchins (Arafeh-Dalmau et al., 2025). Heatwaves in particular, as a result of climate change, are compromising kelp forests’ capacity to provide coastal protection, nutrient cycling, and carbon sequestration, all costing billions of dollars to humanity (Smale, 2019). The combined eff ects of these stressors has reduced the ability for kelp forests to bounce back and recover, and as foundation species, their loss can profoundly impact hundreds to thousands of species that rely on them (Arafeh-Dalmau et al., 2025; Rogers-Bennett, 2019).