Impacts of Ocean Acidification on Coralline Algae : From Species to Community Consequences

• Main Author: Shen, Chenchen
• Other Authors: Menge, Bruce A., Nielsen, Karina J., Chan, Francis, Langdon, Chris, Jones, Julia A., Integrative Biology, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Carbon dioxide > Physiological effect > Pacific Coast (U.S.); Ocean acidification > Pacific Coast (U.S.); Coralline algae > Pacific Coast (U.S.); Pacific; Ocean acidification
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/4j03d1903

Oceanic uptake of rising anthropogenic CO₂ emissions has caused the emergence of ocean acidification as a major threat to marine ecosystems worldwide. Along eastern boundary current systems, seawater is naturally acidified due to coastal upwelling of low pH seawater from depth. Compounded by ocean acidification, upwelling regions are expected to become increasingly corrosive to calcifying organisms, potentially forcing them beyond their physiological tolerance windows. In my dissertation, I focused on the impacts of ocean acidification on calcareous coralline algae in the California Current System. Using coralline algae in rocky intertidal habitats as model organisms, I extend the implications of ocean acidification from the organismal level to the broader community level. Global environmental change implies not only gradual changes in the mean values of environmental variables but also an increase in variability and the likelihood of rare, extreme events. In Chapter 2, I conducted a laboratory experiment to explore potential interactions between two different types of environmental stressors. Specifically, I tested the effects of elevated pCO₂, including variable pCO₂ treatments, and a severe desiccation event on the coralline species, Corallina vancouveriensis. I found that C. vancouveriensis growth was negatively impacted by both elevated pCO₂ and desiccation stress, although their combined effects were approximately additive rather than synergistic. Furthermore, while high pCO₂ at constant levels only caused small reductions in algal growth over a two-week period, these effects were exacerbated by pCO₂ variability. One criticism of laboratory experiments testing species responses to environmental change is that they isolate organisms under simplified conditions. The potential of overlooking important biotic or abiotic factors present in the natural environment limits the inferences that can be made from laboratory studies. In Chapter 3, I conducted a reciprocal removal experiment at two field sites and two ...