3 March 2008:
Ocean acidification may affect photosynthesis in marine algae
MBARI researcher Zbigniew Kolber will present findings on the effects of ocean acidification on photosynthesis in the sea at a press conference during the 2008 Ocean Sciences Meeting March 2 through 7 in Orlando, Florida. Kolber’s lab team grew phytoplankton (microscopic marine plants) under conditions that mimic an acid environment predicted 100-300 years into the future. When the pH (the measure of change in acidity) shifted by more than 0.25 units, key steps in the chemical process of photosynthesis were affected. Under conditions typical of the coastal ocean, acidic shifts greater than 0.5 pH units reduced phytoplankton growth rates by 10-20%. Current estimates indicate that upper ocean pH has already shifted 0.1 units worldwide. Phytoplankton generate roughly half of the oxygen we breathe and are often called the “lungs of the planet.” In addition to Kolber’s talk, other MBARI researchers will offer more than 35 presentations during the meeting.

22 January 2008:
Subtropical oceans add oxygen to atmosphere
The subtropical Pacific is a net source of oxygen for the Earth’s atmosphere, according to a new paper published in the Jan. 17 issue of Nature by MBARI marine chemist Kenneth Johnson and Stephen Riser of the University of Washington. Over three-quarters of the ocean’s surface waters are clear and blue and do not sustain much life because they are nutrient poor. For decades, oceanographers have debated whether algae living in these ocean regions are net producers or consumers of oxygen. Indirect measurements indicated that these algae were producing half of the oxygen in the atmosphere, but previous attempts to measure oxygen production directly suggested that these regions were consuming oxygen. A new oxygen sensor enabled Riser and Johnson to measure oxygen production rates in the subtropical open ocean over several years. They found that each fall, the surface waters mix, creating a uniform layer of low-oxygen seawater. Starting in spring, oxygen accumulates steadily about 100 meters below the surface, at a rate that indicates marine algae are producing more oxygen than they consume over the course of the year.

11 January 2008:
Marine scientists question commercial plans for ocean fertilization.
In the January 11 issue of Science magazine, MBARI chemical oceanographer Ken Johnson joined 14 other prominent marine scientists from around the world in stating that there is not enough scientific information to justify selling carbon sequestration credits based on ocean iron fertilization. Several private companies have claimed that they can reduce global warming by dumping large quantities of iron into the ocean. These companies claim that the iron will stimulate the growth of marine algae, which will take up carbon dioxide from the atmosphere and then sink to the seafloor. Johnson and other scientists state that there is not yet enough scientific evidence to determine whether such schemes would be effective. In addition, they suggest that such strategies could pose risks to the marine environment, but that these risks cannot be assessed based on currently available information.