Why does this matter; because we all need oxygen (Link), and know almost nothing about the impact of ocean acidification on oxygen producing cyanobacteria. Mini ice on the way or not, more atmospheric carbon dioxide = more acid oceans; are we seeing the edge of a process of extinction of mammals, with an unqualified window of opportunity to prevent disaster?

Abstract From Science Magazine- harbingers of a bigger issue? More Info
05 Jan 2018:
Vol. 359, Issue 6371, eaam7240

Oxygen concentrations in both the open ocean and coastal waters have been declining since at least the middle of the 20th century. This oxygen loss, or deoxygenation, is one of the most important changes occurring in an ocean increasingly modified by human activities that have raised temperatures, CO₂ levels, and nutrient inputs and have altered the abundances and distributions of marine species.

Oxygen is fundamental to biological and biochemical processes in the ocean. Its decline can cause major changes in ocean productivity, biodiversity, and biochemical cycles. Analyses of direct measurements at sites around the world indicate that oxygen-minimum zones in the open ocean have expanded by several million square kilometers and that hundreds of coastal sites now have oxygen concentrations low enough to limit the distribution and abundance of animal populations and alter the cycling of important nutrients