Ocean Acidification
Ocean
acidification is becoming an increasing problem as more CO2 enters
into the atmosphere. The ocean absorbs
about one third of the CO2 from the atmosphere. For a long period of time the amount of CO2
absorbed by the oceans stayed fairly stable.
However, as humans continue to allow more CO2 to enter the
atmosphere, the ocean continues to absorb more and more of this available CO2.
This
increase in CO2 concentration leads to a decrease in the PH of the
water (acidity increase, moving towards 7 on a PH scale). This is a progressive change that occurs, and
is known as ocean acidification. This change affects many different organisms
which range from copepods to much larger organisms (such as ones that need
calcium carbonate to build their shells), in all different levels of
development. This change in PH is causes
for a change in concentrations of certain chemicals in the water. These chemical changes are an increase in the
concentration of hydrogen ions, and a decrease in the concentration of
carbonate ions. These changes can have major
effects on many organisms. The two major
effects to organisms are the inability to form shells by shell forming
organisms, as well as the life cycles and reproductive success of many marine
organisms may be altered.
Ocean
acidification is seeming to have a major influence on the organisms that need
to use calcium carbonate to build their shells (Kerr, 2010). There are two different ways that the calcium
carbonate in the water is being depleted due to the change in PH (and thus the
change in hydrogen ion concentration).
First is that as the hydrogen ion concentration gets higher, the calcium
carbonate produced by these organisms begins to dissolve. The second problem is that the increased
hydrogen ion concentration will combine with the free calcium carbonate in order
to form bicarbonate. From this reaction
all of the free calcium carbonate in the water is used up and is not
replenished. Without this calcium
carbonate being available the organisms are unable secrete or collect enough
calcium carbonate in order to produce their shells.
Although
large organisms can be affected by the PH change, organisms that are lower down
on the food chain (such as copepods) can also be affected. All life stages of the copepods are affected
by the increasing concentration of CO2 in the water (Cripps et al.,
2014). However, the larval stage of the
copepods are most affected. At this
stage in their life cycle, they are unable to adapt to the increasing
concentration of CO2. There
is also a drastic negative effect on reproduction in copepods. There is a very clear trend that shows as the
concentration of CO2 increases the reproductive success
decreases. This lack of survival in the
larval stages of the life cycle and the poor reproductive success leads for
there to be less copepods surviving.
As it can
be seen, many different organisms are affected by the decreasing PH (ocean
acidification). This includes the
organisms that are on the bottom of the food chain (such as the cephalopods and
zooplankton). As the ocean acidification
continues, the amount of these organisms will continue to decrease. This will have dire effects on the marine
food web in general, as there will not be enough food for the organisms above
the bottom level to eat.
These dire
effects leads this to be a conservation issue.
Further research needs to be done to completely understand the effects
of ocean acidification. Research needs
to be done in order to understand which species is effected the most. Research also needs to be done in order to
understand whether any marine species are able to adapt to the new
conditions. Finally, research needs to
be conducted in order to understand whether these chemical conditions of the
water can be changed back with time.
Words: 640
Literature Cited:
Cripps, Gemma; Lindeque, Penelope; and Flynn, Kevin J. [Internet] Have we been underestimating the effects of ocean acidification in zooplankton. Global Change Biology, 20: 3377-3385 [Cited January 20,2016] Available from: http://eds.b.ebscohost.com.ezproxy.tru.ca/eds/pdfviewer/pdfviewer?vid=2&sid=38741adc-4f79-41a5-8a69-06a2a6089e24%40sessionmgr114&hid=127 DOI: 10.111/gcb.12582
