Elisabeth MA Strain1,2, India Ambler2, Rebecca L Morris2 Kerry J Nickols3 and Stephen Swearer2
1Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
2School of Biosciences, University of Melbourne, Melbourne, VIC, Australia
2Department of Biology, California State University, Northbridge, California, USA
Kelp forests are some of the most productive, diverse, and high-valued ecosystems on Earth which are threatened by future climate change stressors. In some locations, kelps can play an important role in ameliorating the local effects of ocean acidification through the uptake of CO2 during photosynthesis. The effects of kelps on local seawater chemistry (pH and O2) in different environmental conditions remains unknown. Here we conducted a literature search and field measurements to quantify the responses and effects of kelps on seawater chemistry in different hydrodynamic conditions. Our results showed that the proportion of studies which tested the effects of kelps on seawater pH and O2 was significantly lower than those which assessed the impacts of future changes in seawater chemistry or hydrodynamics on kelps. Field measurements demonstrated that natural kelp (Ecklonia radiata) forests had higher values of pH (~0.1 units) and O2 (2.21 mg/L) during the day than bare rock barren habitat, but the differences were only significant when conditions were calmer. Our results suggest that the benefits of kelp forests in providing local climate refuges to calcified species from ocean acidification are variable through time and could be dampened by the increased wave exposure and storminess associated with climate change.