The Effects of Ocean Acidification on Hyas lyratus’ Metabolic Processes Qui ckTi m e™ and a TIFF (LZW) decompres sor are needed to see this pi c ture. Quic kTime™ and a TIFF (LZ W) decompres sor are needed to see this pic ture. 1, 2 Elena Fernandez ‘08 and 3 Dr. Sherry Tamone 1Kenyon College Dept. Of Biology, 2University of Alaska Southeast REU Scholar 2007 3University of Alaska Southeast Dept. of Marine Biology Abstract Recent studies indicate that increasing amounts of atmospheric CO2 dissolving into the Introduction ocean biome are causing acidification of the marine environment. Some predictive Take Home Message and The world’s oceans function as a carbon sink. As atmospheric CO2 levels rise, the equilibrium of the marine carbon cycle is unbalanced and oceanographic models indicate that pH will drop up to 0.5 pH units over the next 100 years. It is Future Directions more carbonic acid is formed as a result1. This causes marine pH to well documented that ocean acidification inhibits the ability of organisms to form and maintain decrease leading to ocean acidification. Modeling studies have shown •Overall change in SMR was significant when that marine pH will decrease about 0.3-0.5 units every 100 years at the calcium carbonate structures. Examples of such organisms are diatoms, mollusks, and exposed to lowered pH. current rate of increasing CO2 levels in the atmosphere2,3. The increasing crustaceans. The physiological cost to crustaceans that must regulate internal pH and must acidity has been shown to inhibit the production of shells in certain marine •All metabolic enzymes demonstrated a significant organisms (pteropods and arthropods), as well as coral bleaching4,5. It is form a calcareous exoskeleton during each larval, juvenile and adult molt cycle remains unclear. possible that populations of commercially harvested species will be We measured standard metabolic rates of female lyre crabs, Hyas lyratus that were acclimated decrease in enzyme activity in acidified samples. adversely affected by this added stressor, causing a potential economic crisis for the fishing industry. for one week at pH 8, pH 7.5, pH 7.0, and pH 6.5. Metabolic rates were significantly different Studies have shown that invertebrates cannot effectively acclimate between crabs held at pH 8 and pH 6.5 (0.55 vs. 0.43 ml O2/kg/min). Enzymatic rates of lactate •A number of potential studies could build on this to acidic conditions, potentially adversely affecting overall metabolism6,7,8. dehydrogenase (LDH), pyruvate kinase, and citrate synthase decreased significantly with It is also possible that metabolic enzymes could also show decreased research to gain a better understanding of the activity in acidic conditions, as enzymes have a narrow range of pH levels decreased pH. This decreased activity of LDH could be detrimental to physiological processes mechanism underlying decreased pH on metabolism. in which they function. that require anaerobic metabolism. In fact, increased mortality was observed in crabs that were Possible research topics include: the response to These studies were conducted to investigate the potential influence acclimated to pH 7.5, pH 7.0 and pH 6.5 and exposed to hypoxia for 24 hours when compared anoxic stress under acidified conditions, a of pH on metabolic rates. Our model organism was the lyre crab Hyas lyratus, a relative of the commercially important Majid family of crabs with control crabs held at pH 8.0. It is likely that there is an energetic cost to crabs associated comparative metabolic enzyme study of shallow and Chionoectes biardi and C. opilio. Crabs will be exposed to view the with ocean acidification and that this cost could have a negative impact on energetically costly deep water crabs exposed to acidic conditions, and effects of a gradient of environmental acidifications on overall metabolic rate as well as metabolic enzyme activity. physiological processes such as growth and reproduction. hemolymph buffering capacity of different crab species acclimated to lower environmental pH levels. Questions and Hypotheses •Does acidification show a significant effect on the standard Results metabolic rate (SMR)? 0.7 •Hypothesis: There will be a significant increase in 140 PK Activity (OD/min) standard metabolic rate of crabs exposed to lowered pH. 0.6 Acknowledgements MR (ml O2/kg/min) A 120 0.5 100 • ASLO for allowing me to present at today’s conference. B A •Which metabolic enzymes (PK, LDH, CS) does ocean 0.4 80 • NSF and NOAA for project funding. pH 8 acidification significantly affect, and how? 0.3 pH 7.5 pH 7 60 pH 8.0 • University of Alaska Southeast, specifically Dr. Sherry Tamone, Dr. Matt pH 6.5 pH 7.5 Heavner, and Beth Mathews. •Hypothesis: There will be significant upregulation of 0.2 40 pH 7 • The crabs for their sacrifice. May they rest in peace. metabolic enzymes as the environmental pH decreases. 0.1 20 pH 6.5 • University of Alaska Fairbanks graduate students for their literature help, B B B fishing trips, and entertainment in and out of the lab. 0 0 Environmental pH Test group • REU comrades for their ideological support and the adventure of a lifetime. Methods Figure 1. Average SMR of all test groups. (ANOVA p=0.32, Figure 2. Pyruvate kinase reaction rates for n=20 crabs. Error=SEM. 2-Sample post T-test comparing the extreme pH test (Error=SEM; ANOVA p=0.003. 2-Sample post T-test showed that Organism Capture and Husbandry groups shows a difference, p=0.03). for groups with different letters p=<0.05). • Ovigerous females captured using crab pots off Spuhn Island, Juneau, AK. •All crabs were fed herring twice a week ad libidum and allowed to 25 LDH Activity (OD/min) CS Activity (OD/min) 35 acclimate to tanks for one week. Baseline standard metabolic rate Works Cited (SMR) was determined using a YSI oxygen meter in a closed system. 30 A 20 1. Herzog, et al. “Environmental Impacts of Ocean Disposal of CO2.” Energy Convers A Mgmt. 37:6-8 (1996) 999-1005. •Carbon dioxide bubbled into test tanks to decrease pH to either 7.5, 25 pH 8.0 15 2. Pelejero, et al. “Preindustrial to Modern Interdecadal Variabilty in Coral Reef pH.” 7.0, or 6.5. One tank was kept at ambient pH and used as a control. 20 pH 7.5 Science. Vol. 309 (2005) 2204-2207. pH 8.0 3. McNeil and Matear. “Projected climate change impact on oceanic acidification.” Carb. •All organisms were allowed to acclimate to acidified conditions for one 15 pH 7 10 Bal. Mgmt. 1:2 (2006). pH 7.5 week prior to testing. A pH 7 Feeley, et al. “Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans.” 10 pH 6.5 4. 5 pH 6.5 Science. 305 (2004) 362-366. SMR and Enzyme Assays 5 B Pala. “A World Without Corals?” Science. 316 (2007) 678-681. C B B B 5. •Crab weighed and placed in metabolic chamber for ~80 minutes. 0 6. Spicer, et al. “Influence of CO2-related seawater acidification on extracellular acid-base 0 Test group balance in the velvet swimming crab Necora puber.” Mar Biol. 151(2007)1117-1125. •Measured %change in oxygen over the allotted period of time. Test Group 7. Miles, et al. “Effects of anthropogenic seawater acidifiction on acid-base balance in the Figure 3. LDH activity in the four different test groups. Figure 4. CS activity in the test groups. (Error=SEM; ANOVA •Animals were sacrificed and gill and muscle tissue samples taken from (Error=SEM; ANOVA p=0.000; 2-Sample post T-Tests indicate p=0.000; 2 Sample post T-test show groups with different sea urchin Psammechinsu miliaris” Mar. Poll. Bull. 54(2007) 89-96. carcasses. 8. Pane, Eric and James Barry. 2007. “Extracellular acid-base regulation during short-term groups with different letters have p=<0.05.). letters are p=<0.05.). hypercapnia is effective in a shallow-water crab, but ineffective in a deep-sea crab.” •LDH, CS, and PK enzyme activity were measured using known Marine Ecology Progress Series. 334: 1-9. protocols.
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