Acidic Oceans Will Hinder Reproduction of Marine Invertebrates

Rising ocean acidity due to more atmospheric CO₂ will impair fertilization of the eggs of sea urchins, lobsters, mussels, and oysters and significantly reduce their fertilization rates by 2100, a study in Current Biology reports. A team of Australian and Swedish scientists observed that as seawater grew more and more acidic, sea urchin sperm moving to reach eggs faltered and slowed, with a 25 percent reduction of fertilization when the pH reached 7.7, the projected level for 2100. Though seawater usually has a pH of 8.1, pHs of 7.7 have already been detected off the west coast of the U.S. Even when eggs were fertilized, 26 percent of them failed to develop into larvae, indicating that increased acidification may also impact early development. Scientists have already observed that ocean acidification corrodes the shells of marine animals, but have only recently begun to realize that it may have additional effects on sea life.