Ocean acidification and its impact on coral reefs
Edit Date: 2016-06-05 10:56:17
Question:

Ocean Acidification is: the ongoing decrease in the PH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2) from the  atmosphere. Seawater is naturally slightly basic (meaning pH > 7).

Why Coral Reefs are important?

They act as a natural coastal barrier, they support Biodiversity, they are an habitat for third of all fishes at some point of their lives (!) , they are a food source and support the local economy by being a tourism site.  Also - many modern medical advances focus on marine organisms. 


Below is a reading section and a data graphs of the processes described in the reading section.
Please read the section and the accompanying graphs, and at the end answer the question.

Reading section: Ocean acidification and its impacts on coral reefs

Oceans play an important role in the natural carbon cycle by absorbing part of the carbon dioxide contained in the atmosphere. Calculations show that the oceans are responsible for absorbing half of the man-made emissions until 1994 and just 30% of the emissions since.

Ocean carbon dioxide absorption has another result - ocean water acidification. For the next 100 years the forecast shows a reduction of 0.5 to 0.3 pH units for the surface waters of the oceans.


A decrease in pH value ​​entails physiological consequences for various processes, especially on limestone skeleton-based organisms (carbonate). Skeletal construction rates of limestone reef-building corals have fallen in recent years due to rising concentrations of carbon dioxide in the oceans waters. Additionally, these chemical changes in the ocean are likely to weaken existing coral skeletons and reduce the growth of reefs. This phenomenon is called coral bleaching, because the dying corals loose there colors and turns white.

A new study describes a decrease of 13% in the rate of limestone skeletal construction since 1990 at the Great Barrier Reef in Australia - the world's largest reef. Researchers attribute it to a combination of two processes: ocean acidification and rising temperatures (rising temperatures harm corals in a different way than acidification).

Models predict that with a doubling of the concentration of carbon dioxide in the atmosphere, coral reefs will stop growing altogether, and instead begin to dissolve. This prediction is very gloomy, considering the rich variety of  marine species.

(This section was taken and edited from the article: "The effects of global climatic change on marine ecosystems: the global situation and the implications for the marine environment in Israel", by Gil Rilob and Haim Treves, the magazine "Ecology and Environment", January 2010, No. 1, (pp 65-57)) .

Coral Bleaching at the Great Barrier Reef


The Data Graphs :



Legend:

Top graph (a):

Red - Hawaii

Black - Antartics

Bottom graph (b):

Dark green  blue - the Atlantic ocean

Light green  blue - the Pacific ocean


(The graphs are from a presentation "Climate Change in the Middle East of the 21st century - perception and reality," Prof. Yoav Yair, School of Sustainability, Herzeliya, a seminar Communication and Environment, 3rd of December 2015)



Fuel, coal, oil and natural gas combustion are producing gases, which accumulate in the atmosphere, including carbon dioxide (CO2). The accumulation of these gases causes many changes on Earth, such as rising the temperature of the atmosphere, which impacts marine organisms such as coral reefs.


How does the increase of atmospheric carbon dioxide affect coral reefs?
Question Created By: Yasmine Abu Nimer
Creation Date: 2016-05-14 12:08:58
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