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									          The Effects of Ocean Acidification on Hyas lyratus’
                         Metabolic Processes
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                                                                     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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