Project: OCE-RIG: Changes in Herbivore-Algal Interactions in Kelp Forest Ecosystems in Response to Ocean Acidification

NSF abstract:

Kelp forest ecosystems provide food for commercial and recreational fisheries, support biodiversity, and promote tourism in coastal communities. In this project, the investigator will examine how accelerating environmental changes could affect kelp forest ecosystems and coastal communities by studying the ecological processes influencing the survival of young kelp. Research results may contribute to management of kelp forest ecosystems as increased storm frequency and intensity elevates the importance of processes affecting the survival of young kelp (i.e., herbivory) in the recovery and persistence of future kelp forests. In addition, training opportunities for graduate and undergraduate students from under-represented groups in STEM are integrated into the research plan.

The overall objective of this project is to determine how seawater temperature and carbonate chemistry combine to affect the interactions between a wide range of invertebrate herbivores and the early life history stages of giant kelp, Macrocystis pyrifera. In kelp forest ecosystems, herbivores can limit survival of juvenile kelp following disturbances when populations must reestablish from microscopic stages. Recovery dynamics in kelp forests may be especially important in future scenarios with projected increases in disturbances (e.g., storminess and extreme events). When combined, warming and ocean acidification can substantially reduce the survival of early life history stages of kelp thereby increasing the importance of herbivory in regulating kelp forest recovery and dynamics in a high CO2 world.

This project will examine benthic communities from kelp forests in the California Current, an area of rapid acidification. Using a factorial laboratory experiment, the effects of future temperature and CO2 scenarios on per capita and per population interaction strengths of a wide range of herbivore species on the early life history stages of the giant kelp will be tested. The the effects of warming and ocean acidification on the nutritional quality and palatability of M. pyrifera will also be tested, which could indirectly affect interaction strengths.