Development of a Continuous Phytoplankton Culture System for Ocean Acidification Experiments

Abstract

Abstract:Around one third of all anthropogenic CO 2 emissions have been absorbed by the oceans, causing changes in seawater pH and carbonate chemistry. These changes have the potential to affect phytoplankton, which are critically important for marine food webs and the global carbon cycle. However, our current knowledge of how phytoplankton will respond to these changes is limited to a few laboratory and mesocosm experiments. Long-term experiments are needed to determine the vulnerability of phytoplankton to enhanced pCO 2 . Maintaining phytoplankton cultures in exponential growth for extended periods of time is logistically difficult and labour intensive. Here we describe a continuous culture system that greatly reduces the time required to maintain phytoplankton cultures, and minimises variation in experimental pCO 2 treatments over time. This system is simple, relatively cheap, flexible, and allows long-term experiments to be performed to further our understanding of chronic responses and adaptation by phytoplankton species to future ocean acidification.

Species-Specific Variations in the Nutritional Quality of Southern Ocean Phytoplankton in Response to Elevated pCO2

“…Bubbling is a simple and effective way of altering the carbonate chemistry in agreement with natural changes [51]. The culture system is described in detail elsewhere [52] and will be summarized briefly below.…”

Impact of Ocean Acidification on Marine Organisms—Unifying Principles and New Paradigms

“…The finding that simulated ocean acidification had no significant effects on the growth and skeletal structure of the adult stages of two widespread cold-water corals [3], but can be particularly severe for organisms which start to calcify in their larval and/or juvenile stages [1] and there may also be indirect effects through loss of food quality since rising CO2 levels affect the biochemistry of phytoplankton [7,8] highlights the fact that there is likely to be significant variations in species' responses. The otoliths of squid embryos are affected by the combined effects of acidification and lowered oxygen, although conditions within the brood capsule also affect their geochemistry.…”

“…Cathryn Wynn-Edwards, at the Institute for Marine and Antarctic Studies, University of Tasmania, draws attention to the fact that increased seawater pCO2 has the potential to alter phytoplankton biochemistry, which in turn may negatively affect the nutritional quality of phytoplankton as food for grazers. To address this issue Wynn-Edwards et al [7] developed an inexpensive phytoplankton culture system for ocean acidification experiments that reduces the time required to maintain cultures in exponential growth for extended periods of time. This system was used to investigate the nutritional quality of southern ocean phytoplankton in response to elevated pCO2 with colleagues at the University, at CSIRO Division of Marine and Atmospheric Research and at the Australian Antarctic Division [8].…”