The Effects of Climate Change on Macroalgal Growth, Trophic Interactions and Community Structure

• Main Author: Ober, Gordon
• Format: Text
• Language: unknown
• Published: DigitalCommons@URI 2016
• Subjects: Ocean acidification
• Online Access: https://digitalcommons.uri.edu/oa_diss/490; https://doi.org/10.23860/diss-ober-gordon-2016; https://digitalcommons.uri.edu/context/oa_diss/article/1512/viewcontent/Ober_uri_0186A_11529.pdf

Global climate change is threatening the structure, function, and health of ecosystems. While factors of climate change have been studied extensively over the past few decades, most research has focused on the response of single organisms or populations; as our ecosystems are comprised of complex interactions and relationships, it is of critical importance to understand how entire communities are going to be impacted by climate change. Ocean acidification (a by-product of increased atmospheric carbon dioxide, CO2), and nutrient loading are two major forces of global change that are projected to have detrimental impacts on coastal marine species and ecosystems. Most work on ocean acidification has focused on the response of calcifying organisms, where the changes in ocean chemistry associated with acidification enhance shell dissolution and impair growth. However, while calcifying species are expected to exhibit negative responses to acidification, primary producers, like macroalgae, are expected to flourish. Both ocean acidification and nutrient loading can stimulate the growth and productivity of opportunistic, fast-growing, ephemeral macroalgae at the expense of foundational species such as corals, seagrasses, and long-lived, perennial macroalgae (i.e. kelps). As a result, these ecosystems will likely undergo major shifts in structure, function, and diversity. Few studies have investigated the interactive effects of ocean acidification and nutrient loading, particularly in terms of community response and trophic interactions. Despite increasing the growth rates of macroalgae, the presence and diversity of herbivores within an ecosystem has the potential to control this expected algal growth. The research described in this dissertation aims to: 1) quantify the combined effects of ocean acidification and nutrient loading on the growth, tissue quality, and competition of two abundant macroalgal species with different life histories; 2) test whether or not an abundant grazer can enhance consumption of macroalgae ...