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- Title
- A case study of ocean acidification and South Florida’s coral reefs.
- Name/Creator
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Camden, Lauren
- Abstract/Description
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Levels of the greenhouse gas carbon dioxide have been increasing dramatically in the atmosphere since the onset of the Industrial Revolution with a sharp escalation occurring due to anthropogenic causes such as the burning of fossil fuels. The ocean acts as a carbon sink for this atmospheric CO2, absorbing a large majority of it. This process causes a chemical reaction that has been increasing the acidity level of ocean water and progressively lowering the average pH value. When a carbon...
Show moreLevels of the greenhouse gas carbon dioxide have been increasing dramatically in the atmosphere since the onset of the Industrial Revolution with a sharp escalation occurring due to anthropogenic causes such as the burning of fossil fuels. The ocean acts as a carbon sink for this atmospheric CO2, absorbing a large majority of it. This process causes a chemical reaction that has been increasing the acidity level of ocean water and progressively lowering the average pH value. When a carbon dioxide molecule is absorbed into sea water, two positively charged ions are produced. Because pH value is a measurement of hydrogen ion concentration in any given solution, these added hydrogen ions effectively lower the pH value of the ocean. Since these hydrogen ions are positively charged, they go on to interact with the negatively charged bases already present in the ocean. One of these bases is CaCO3, or the carbonate ion. Carbonate is essential to calcifying marine organisms, who use this ion to build and maintain their shells and skeletons. However, as atmospheric carbon dioxide levels increase and the resulting chemical reactions occur, the ocean’s carbonate saturation decreases. Coral is one such calcifying organism that essential to the aquatic ecosystem in a number of ways, most of which can be attributed to the fact that coral reefs are one of the planet’s most biodiverse ecosystems despite inhabiting only a very small portion of the ocean. Several studies have linked coral’s carbonate production to their ability to create functional skeletons. One such study was published by Kuffner et al in 2013 in the Florida Keys. Four sites ranging from Miami to the Dry Tortugas were selected, and two batches of forty Siderastrea siderea (massive starlet coral) each were selected for two experimental runs. At six-month intervals, these samples were analyzed to determine linear expansion rates and calcification levels. After analysis in both runs, a strong correlation between linear expansion rates and calcification levels was determined. Corals that experienced heightened calcification rates also experienced heightened linear expansion. This experiment solidified the negative affect ocean acidification will have in future years on coral reefs if left unacknowledged. Langdon et al also published an experiment done in the Florida Keys in 2013 that determined a relationship between increased atmospheric CO2 levels and decreased calcification rates of coral. Eleven samples of a combination of Siderastrea radians (shallow water starlet coral) and Solenastrea hyades (smooth star coral) were epoxied to cinderblocks with sensors recording environmental data at thirty-minute intervals. Random samples were incubated in tanks in situ and given a treatment regime designed to simulate increased ocean acidification conditions through chemical injections of NaHCO3 (sodium bicarbonate) and HCl (hydrogen chloride). This treatment lowered pH value in the incubation chambers by 0.1 to 0.2 units. Calcification rates of the incubated coral samples were determined through statistical analysis. Coral samples that experienced a 0.1 unit drop in pH value experienced decreased calcification rates of 50% and coral samples that experiences a 0.2 unit drop in pH value experienced a decreased calcification rate of 52%. Both of these studies combined showcases the two-part threat ocean acidification is placing on coral reefs in the Florida Keys. As the average pH of ocean water drops, corals are unable to achieve net carbonate accretion and calcification rates drop. This causes corals to experience stunted linear expansion, density, rugosity, and reproduction rates. As coral population dwindles, Florida will experience several negative socio-economic impacts such as diminished coastal protection from storms, tourism, income and jobs created by fisheries, and medicinal opportunities as new life-saving medicines will no longer be able to be harvested from dying reefs. Mitigation and adaptation methods must include reducing other local stressors to coral.
Show less - Date Issued
- 2020-06-15
- Identifier
- BC744
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/broward/fd/BC744
- Title
- A literature review of ocean acidification’s effect on coral calcification rates and skeletal growth.
- Name/Creator
-
Camden, Lauren
- Abstract/Description
-
Ocean acidification is one of many threats to marine life as a result of increasing levels of atmospheric carbon dioxide being absorbed by ocean water. Anthropogenic levels of carbon dioxide have been rising dramatically in the atmosphere since the onset of the Industrial Revolution, with a sharp escalation occurring due to practices such as the burning of fossil fuels. The ocean acts as a carbon sink for atmospheric CO2, absorbing a large portion of it. This process causes a chemical...
Show moreOcean acidification is one of many threats to marine life as a result of increasing levels of atmospheric carbon dioxide being absorbed by ocean water. Anthropogenic levels of carbon dioxide have been rising dramatically in the atmosphere since the onset of the Industrial Revolution, with a sharp escalation occurring due to practices such as the burning of fossil fuels. The ocean acts as a carbon sink for atmospheric CO2, absorbing a large portion of it. This process causes a chemical reaction that progressively lowers the average pH of oceans globally. When a carbon dioxide molecule is absorbed into sea water, two positively charged ions are produced. As pH value is a measurement of hydrogen ion concentration in any given solution, these added hydrogen ions effectively lower the pH of the ocean and causes it to be more acidic. Since these hydrogen ions are positively charged, they to interact with the negatively charged bases already present in the ocean. One of these bases is CaCO3, or the carbonate ion. Carbonate is essential to calcifying marine organisms, who use this ion to build and maintain their shells and skeletons. However, as atmospheric carbon dioxide levels increase and the resulting chemical reactions occur, the ocean’s carbonate saturation decreases. Coral is one such calcifying organism that essential to the aquatic ecosystem in a number of ways, most of which can be attributed to the fact that coral reefs are one of the planet’s most biodiverse ecosystems despite inhabiting only a very small portion of the ocean. With this process occurring at accumulative speeds, how will ocean acidification affect the calcification rates- and therefore the growth and development- of coral in the coming years worldwide? Several studies have confirmed the relationship between increased carbon dioxide levels and the resulting decreased calcification levels and structural deformities present in coral reefs. In 2005 Langdon et al published a study that tested coral calcification rates with varying rates of carbon dioxide saturation in ocean water. Specimens of Porites compressa (finger coral) and Montipora verucosa (rice coral) were collected off the coast of Hawaii and placed in an offshore experimental flume where a series of incubations were performed in Summer 1999 and Winter 2000. From August to September 1999, eighteen incubations were performed with ambient conditions and nine incubations were performed with pCO2 levels at 1.7 times what ambient conditions were. A second round of fifteen incubations were performed from January to February 2000. Six incubations were done at an ambient pCO2, two were done at 1.4 times, and six were done at 2.0 times ambient conditions. Calcification rates for all incubations were calculated through statistical analysis. As a result, calcification decreased 26%, 40%, and 80% respectively to increased pCO2. Another such study was conducted by Langdon et al again in 2013, this time in the Florida Bay. Samples of Siderastrea radians (shallow starlet coral) and Solenastrea hyades (smooth star coral) were collected near Peterson Key and attached to cinderblocks with sensors logging environmental data such as pH and temperature at thirty-minute intervals. A random subset of these corals was incubated in situ and given a treatment regime designed to simulate increased ocean acidification conditions. This treatment lowered pH value in the incubation chambers by 0.1 to 0.2 units. Calcification rates of the incubated coral samples were determined through statistical analysis. Coral samples that experienced a 0.1 unit drop in pH value experienced decreased calcification rates of 50% and coral samples that experiences a 0.2 unit drop in pH value experienced a decreased calcification rate of 52%. These studies both exemplified the strong correlation that exists between pCO2 present, increased acidity in ocean water, and decreased calcification rates of coral. In 2016, Foster et al published a study that demonstrated the structural deformities coral experience as a result of this calcification reduct.
Show less - Date Issued
- 2020-06-15
- Identifier
- BC742
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/broward/fd/BC742
