Monday, June 15, 2015
Coral not co-operating with Warmist theory
As the ocean absorbs atmospheric carbon dioxide (CO2) released by the burning of fossil fuels, its chemistry is changing. The CO2 reacts with water molecules, lowering the ocean's pH in a process known as ocean acidification. This process also removes carbonate ions, an essential ingredient needed by corals and other organisms to build their skeletons and shells.
Will some corals be able to adapt to these rapidly changing conditions? If so, what will these coral reefs look like as the oceans become more acidic?
In addition to laboratory experiments that simulate future ocean conditions, scientists are studying coral reefs in areas of the ocean where low pH is naturally occurring to try and answer important questions about ocean acidification, which threatens coral reef ecosystems worldwide.
One such place is Palau, an archipelago in the far western Pacific Ocean. The tropical, turquoise waters of the Palau Rock Islands are naturally more acidic due to a combination of biological activity and the long residence time of seawater within its maze of lagoons and inlets. Seawater pH within the Rock Island lagoons is as low now as the open ocean is projected to be as a result of ocean acidification near the end of this century.
A new study led by scientists at Woods Hole Oceanographic Institution (WHOI) found that the coral reefs there seem to be defying the odds, showing none of the predicted responses to low pH except for an increase in bioerosion -- the physical breakdown of coral skeletons by boring organisms such as mollusks and worms. The paper is to be published June 5 in the journal Science Advances.
'Based on lab experiments and studies of other naturally low pH reef systems, this is the opposite of what we expected,' says lead author Hannah Barkley, a graduate student in the WHOI-MIT joint program in oceanography.
Experiments measuring corals' responses to a variety of low pH conditions have shown a range of negative impacts, such as fewer varieties of corals, more algae growth, lower rates of calcium carbonate production (growth), and juvenile corals that have difficulty constructing skeletons.
'Surprisingly, in Palau where the pH is lowest, we see a coral community that hosts more species, and has greater coral cover than in the sites where pH is normal,' says Anne Cohen, a co-author on the study and Barkley's advisor at WHOI. 'That's not to say the coral community is thriving because of it, rather it is thriving despite the low pH, and we need to understand how.'
Friday, June 5, 2015
Coral growth and thriving shows no clear connection to temperature variations
The paper below is not easy for a non-specialist to follow but my heading above sums up its major finding. Global warming won't bother it, in other words
Regional coral responses to climate disturbances and warming is predicted by multivariate stress model and not temperature threshold metrics
Timothy R. McClanahan, Joseph Maina, Mebrahtu Ateweberhan
Oceanic environmental variables derived from satellites are increasingly being used to predict ecosystem states and climate impacts. Despite the concerted efforts to develop metrics and the urgency to inform policy, management plans, and actions, few metrics have been empirically tested with field data for testing their predictive ability, refinement, and eventual implementation as predictive tools. In this study, the abilities of three variations of a thermal threshold index and a multivariate stress model (MSM) were used to predict coral cover and community susceptibility to bleaching based on a compilation of field data from Indian Ocean reefs across the strong thermal anomaly of 1998. Field data included the relative abundance of coral taxa 10 years before the large-scale temperature anomaly, 2 years after (1999–2000), and during the post-bleaching recovery period (2001–2005) were tested against 1) a multivariate model based on 11 environmental variables used to predict stress or environmental exposure (MSM), 2) estimates of the time until the current mean maximum temperature becomes the mean summer condition (TtT), 3) the Cumulative Thermal Stress (CTS) for the full satellite record, and 4) the 1998 Annual Thermal Stress (1998 ATS). The MSM showed significant fit with the post-1998 cover and susceptibility of the coral community taxa (r2 = 0.50 and 0.31, respectively). Temperature threshold indices were highly variable and had relatively weak or no significant relationships with coral cover and susceptibility. The ecosystem response of coral reefs to climatic and other disturbances is more complex than predicted by models based largely on temperature anomalies and thresholds only. This implies heterogeneous environmental causes and responses to climate disturbances and warming and predictive models should consider a more comprehensive multiple parameter approach.
Climatic Change, April 2015