Anthropogenically-induced increases in the acidity of the ocean have the potential to seriously harm marine calcifying organisms by decreasing the availability of carbonate (CO32−) used to make shells. I tested the effects of lowered pH on juvenile Pisaster ochraceus, an intertidal sea star and keystone predator in the eastern Pacific Ocean. Populations of P. ochraceus were greatly reduced by outbreaks of sea star wasting disease, which has the potential to alter community structure and lower biodiversity in the intertidal region. However, large numbers of juvenile P. ochraceus have recruited to the rocky intertidal and their ability to persist will be important for the recovery of P. ochraceus populations. To test the effects of pH, I studied the growth rate, calcification, righting time, and movement and prey-sensing ability in the PISCO laboratory mesocosm at Hatfield Marine Science Center. The results of the experiments showed non-significant trends towards a negative effect of pH on growth rate and righting time. Few studies have been done on the effects of pH on sea stars and the results are highly species-specific. Additional research is needed clarify and make accurate predictions about the effects of pH on juvenile P. ochraceus.
Britsch M. L., 2017. Effects of ocean acidification on growth rate, calcified tissue, and behavior of the juvenile ochre sea star, Pisaster ochraceus. BSc Hons thesis, Oregon State University, 44 p. Thesis.
