Has the pH of our oceans decreased significantly? Lauvset and Gruber say yes, for the North Atlantic Subpolar Gyre.
Nearly every scientific report concerning the effects of ocean acidification on coral reefs describes changes in calcification as a function of the aragonite saturation state (Ωa). Is this the best parameter that we can use to represent calcification condition? Are there any other options?
While calcifying organisms like corals and bivalves are projected to struggle under future levels of carbon dioxide (CO2), non-calcifying seaweeds that use CO2 for photosynthesis are going to exhibit normal, or increased, growth and productivity. Here, researchers show that increases in CO2 result in faster growth rates and increased photosynthetic activity in the invasive red alga, Neosiphonia harveyi. Researchers also tested temperature as an environmental factor and found a greater increase in growth and productivity in algae treated with colder water relative to warmer water. This finding is significant as low temperatures typically limit the growth of an individual alga and limit the range of algal species. Could CO2 increase the geographic range and success of seaweed invasions?
Ship emissions of sulfur and nitrogen oxides (SOx, NOx) can be deposited and form sulfuric and nitric acid in surface water. Do heavily-trafficked trade routes result in “hotspots” of ocean acidification? Hassellöv and her team show “hotspots” that coincide with areas of heavy shipping traffic and seasonal stratification.
Researchers investigated natural trends in carbonate chemistry of the Davies Reef flat in the central Great Barrier Reef on diel and seasonal timescales. They found the reef flat is below a calcification threshold, which implies that a transition in the reef may occur from a state of net calcification to dissolution, around 26.9% of the time during the summer and 14.1% of the time in the winter.