The direct and indirect impacts of ocean warming and acidification on marine invertebrates

• Main Author: Graham, Sarah
• Format: Master Thesis
• Language: unknown
• Published: UNSW Sydney 2014
• Subjects: Ocean warming; Climate Change; Ocean acidification; Peramphithoe parmerong; Adaptive capacity; Thermal tolerance; Phasianotrochus eximius; Macroalgae; Palatability; Herbivorey
• Online Access: https://dx.doi.org/10.26190/unsworks/17215; http://hdl.handle.net/1959.4/54074

Many studies have identified that the direct effects of global warming are going to have detrimental impacts on the growth, development and survival on an array of marine species. Tolerance to stress may however be buffered through acclimation, and adaptive across generations, but our understanding on the role of these mechanisms is limited with respect to global warming. I therefore tested how elevated temperatures may affect the size, survival, fecundity and thermal sensitivity of a marine crustacean Peramphithoe parmerong. The acclimation to their maximum habitat temperature did not affect survival, but it did increase growth, reduce fecundity and increased their tolerance to heat stress. This was however, not adaptive across generations as there were no trans-generational effects in association to survival, size or their capacity to tolerate heat. I also identified that the protocols used to assess thermal sensitivity can have a significant effect on heat tolerance, and future studies should recognise and consider this before assessing the critical thermal limits of an organism, particularly those from aquatic systems. As ocean temperatures rise, so too will the concentration of CO2 (coupled with a lowering pH), and the impact of these stressors, acting simultaneously on species interactions, is not clearly understood. The focus of much of the current research in marine systems is associated with calcifying organisms, however non-calcifying organisms are also likely to be affected, in particular primary producers. The growth rates of five temperate species of macroalgae were significantly reduced by temperatures predicted to occur over the next century. In addition, but independent of temperature, a lower pH also lead to the reduce growth of two species of macroalge. Although, for the one species (Dictyopteris acrostichoides), which was unaffected by either temperature or pH, palatability towards the marine gastropod (Phasianotrochus eximius) increased, when grown under increasingly acidic conditions. Given this, the complexities of both the direct and indirect effects of climate change make it difficult to predict the ‘winner and losers’ in the years to come.