Transcript Aaron Cevallos Advisor: Andreas Andersson, Ph.D. Summer 2010 What is ocean acidification? What is causing it? •The ocean absorbs approximately 1/3rd of the CO2

Aaron Cevallos
Advisor: Andreas Andersson, Ph.D.
Summer 2010
What is ocean acidification? What is
causing it?
•The ocean absorbs approximately 1/3rd of the CO2 emitted to the
atmosphere from the burning of fossil fuels.
•As CO2 dissolves in seawater, the pH of the water decreases. Since the
beginning of the industrial revolution, ocean pH has dropped globally by
approximately 0.1 pH units.
•By the end of this century, we may expect to see changes in pH that are the
greatest in 21 million years.
http://ioc3.unesco.org/oanet/FAQacidity.html
Evidence of ocean acidification at BATS
N. Bates
Bermuda coral reef: the canary in a coal mine?
Buddemeier et al. 2004, based on Veron 1995
[CO32-] across coral
reef platform
-Marginal reef
-Lower [CO32-]
-Healthy reef
-No major industries or pollution
-Natural gradient in [CO32-]
Alex Venn
Outer rim
Mid-platform Inshore
What can we expect in the future ?
Changes in atmospheric CO2 under the "business as usual" scenario to the year 2100 and associated changes in ocean pH
and carbon chemistry. Adapted from Wolf-gladrow et al., 1999
The IPCC expects:
•a drop in ocean pH of about 0.4 pH units by the end of this century
•a 60% decrease in the concentration of calcium carbonate
http://ioc3.unesco.org/oanet/FAQacidity.html
Why is ocean acidification a problem?
 Seawater acid-base balance important in regulating biological
and chemical processes, e.g.:
 Function of enzyme and proteins
 Chemical reaction rates
 Availability of nutrients and trace metals
 CO32- is an essential building block for marine calcifiers
depositing skeletons or shells made of CaCO3†
 Less building material equals slower growth, weaker structures
(similar to osteoporosis in humans) and increased vulnerability to
environmental stress in general
† Ca2+
is the other building block, but there are plenty of calcium in seawater
The Alkalinity Anomaly Method
•The alkalinity anomaly method relies on the principle that
when a calcifying organism produces a mole of calcium
carbonate, total alkalinity is decreased by two moles.
•I will be able to know the exact degree to which synthesis or
dissolution is taking place using this method.
2+
Ca
CO32-
CaCO3
Average Daytime vs. Nighttime Calcification Rates
250
200
150
Average Hourly Daytime Rate of Calcification
Average Hourly Nighttime Rate of Calcification
100
50
0
1
2
3
4
5
6
7
8
9
10
The Buoyant Weighing Method
Calcification (or dissolution)
of a coral sample is inferred
from changes in the sample’s
mass. The weight can be
determined in water using
the formula: Wa = Ww / [1(pw/ps)]
http://www.aagaines.com/man/graphics/scale.jpg
Average Weekly Dry Weight Change (g)
0.8
0.7
0.6
0.5
0.4
Average Weekly Dry Weight Change (g)
0.3
0.2
0.1
0
1
2
3
4
5
6
7
8
9
10
AA Predicted Weight Change vs. BW Actual Weight Change
3.5
3
2.5
2
Predicted Weight Change: Week 1-3
Actual Weight Change: Week 1-3
1.5
1
0.5
0
1
2
3
4
5
6
7
8
9
10
Thank You!