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Dr Christina McGraw

christina_mcgrawPhD, MSc (Washington)

Tel +64 3 479 7907
Location Science II, 5c4
Email christina.mcgraw@otago.ac.nz

For more information about the McGraw Research Group 
https://blogs.otago.ac.nz/christinamcgraw/

Professional background

2017 – present, Senior Lecturer, University of Otago
2015 – 2016, Lecturer, University of New England, Australia
2013 – 2016, Visiting Lecturer and Biogeochemical Sensor Developer, Institute for Marine and Antarctic Studies, Australia 
2011 – 2013, Assistant Professor of Environmental Analytical Chemistry, Clark University, USA
2006 – 2010, Postdoctoral Fellow, University of Otago
2005 – 2006, Postdoctoral Fellow, Dublin City University
1999 – 2004, Ph.D. (Analytical Chemistry) and M.Sc., University of Washington, USA
1999 – BSc (Chemistry), University of Alaska, USA

Research interests

With broad interests in analytical and marine chemistry, my research revolves around the design of field-deployable instrumentation for marine ecosystems.

Christina is also a member of the Coastal People: Southern Skies collaboration that connects communities with world-leading, cross-discipline research to rebuild coastal ecosystems.
Coastal People: Southern Skies

Current research projects include:

The effect of anthropogenic CO2 on our marine ecosystems

Since the industrial revolution, the oceans have absorbed about 1/3 of the anthropogenic CO2 released into the atmosphere. This decreases both seawater pH and carbonate concentration, significantly altering the chemistry of the world's oceans. Our group is developing new laboratory instruments and field-deployable sensors to measure fine-scale changes in carbonate chemistry and to study the impact of global climate change on the world’s oceans.

Deployable environmental sensors

To understand fine-scale spatial and temporal changes, solid-contact fabrication techniques have been used to produce a range of low-cost, disposable ion-selective sensors, including carbonate, pH, lead, cadmium, nitrate, and reference electrodes.

Materials and methods for ion-selective electrodes

New methods for ion-selective electrode (ISE) construction are being used to reduce ion fluxes across the sensor’s membrane, leading to 100-to-1000-fold improvements in detection limit. This work is complemented by new Bayesian models of the sensor’s response, which further improves the accuracy and precision of the measurement.

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Publications

Chen, W.-H., Dillon, W. D. N., Armstrong, E. A., Moratti, S. C., & McGraw, C. M. (2021). Self-referencing optical fiber pH sensor for marine microenvironments. Talanta, 225, 121969. doi: 10.1016/j.talanta.2020.121969

Dillingham, P. W., Hong, C. Y., Cornwall, C. E., Fletcher, D., McGraw, C. M., & Zeng, J. (2021). Multi-driver experiments with different scales of replication. Proceedings of the 14th Annual New Zealand Ocean Acidification Conference: Ocean Acidification in a Decade of Ocean Science. (pp. 13). Retrieved from http://nzoac.nz/conferences

Alsaedi, B. S. O., McGraw, C. M., Schaerf, T. M., & Dillingham, P. W. (2020). Multivariate limit of detection for non-linear sensor arrays. Chemometrics & Intelligent Laboratory Systems, 201, 104016. doi: 10.1016/j.chemolab.2020.104016

Dillon, W. D. N., Dillingham, P. W., Currie, K. I., & McGraw, C. M. (2020). Inclusion of uncertainty in the calcium-salinity relationship improves estimates of ocean acidification monitoring data quality. Marine Chemistry. Advance online publication. doi: 10.1016/j.marchem.2020.103872

Britton, D., Schmid, M., Noisette, F., Havenhand, J. N., Paine, E. R., McGraw, C. M., … Hurd, C. L. (2020). Adjustments in fatty acid composition is a mechanism that can explain resilience to marine heatwaves and future ocean conditions in the habitat-forming seaweed Phyllospora comosa (Labillardiere) C.Agardh. Global Change Biology, 26, 3512-3524. doi: 10.1111/gcb.15052

Journal - Research Article

Chen, W.-H., Dillon, W. D. N., Armstrong, E. A., Moratti, S. C., & McGraw, C. M. (2021). Self-referencing optical fiber pH sensor for marine microenvironments. Talanta, 225, 121969. doi: 10.1016/j.talanta.2020.121969

Alsaedi, B. S. O., McGraw, C. M., Schaerf, T. M., & Dillingham, P. W. (2020). Multivariate limit of detection for non-linear sensor arrays. Chemometrics & Intelligent Laboratory Systems, 201, 104016. doi: 10.1016/j.chemolab.2020.104016

Britton, D., Schmid, M., Noisette, F., Havenhand, J. N., Paine, E. R., McGraw, C. M., … Hurd, C. L. (2020). Adjustments in fatty acid composition is a mechanism that can explain resilience to marine heatwaves and future ocean conditions in the habitat-forming seaweed Phyllospora comosa (Labillardiere) C.Agardh. Global Change Biology, 26, 3512-3524. doi: 10.1111/gcb.15052

Dillon, W. D. N., Dillingham, P. W., Currie, K. I., & McGraw, C. M. (2020). Inclusion of uncertainty in the calcium-salinity relationship improves estimates of ocean acidification monitoring data quality. Marine Chemistry. Advance online publication. doi: 10.1016/j.marchem.2020.103872

Dillingham, P. W., Alsaedi, B. S. O., Granados-Focil, S., Radu, A., & McGraw, C. M. (2020). Establishing meaningful limits of detection for ion-selective electrodes and other nonlinear sensors. ACS Sensors, 5, 250-257. doi: 10.1021/acssensors.9b02133

Ellwood, M. J., Boyd, P. W., Cornwall, C. E., Croot, P., Currie, K. I., Frew, R. D., … Law, C., … McGraw, C. M., … Stirling, C., & Zitoun, R. (2020). Keith Hunter's legacy to marine science in New Zealand. Marine & Freshwater Research, 71(3), i-iii. doi: 10.1071/MFv71n3_ED

Britton, D., Mundy, C. N., McGraw, C. M., Revill, A. T., & Hurd, C. L. (2019). Responses of seaweeds that use CO2 as their sole inorganic carbon source to ocean acidification: Differential effects of fluctuating pH but little benefit of CO2 enrichment. ICES Journal of Marine Science, 76(6), 1860-1870. doi: 10.1093/icesjms/fsz070

Dillingham, P. W., Alsaedi, B. S. O., Radu, A., & McGraw, C. M. (2019). Semi-automated data analysis for ion-selective electrodes and arrays using the R package ISEtools. Sensors, 19(4544). doi: 10.3390/s19204544

van der Loos, L. M., Schmid, M., Leal, P. P., McGraw, C. M., Britton, D., Revill, A. T., … Hurd, C. L. (2019). Responses of macroalgae to CO2 enrichment cannot be inferred solely from their inorganic carbon uptake strategy. Ecology & Evolution, 9(1), 125-140. doi: 10.1002/ece3.4679

Reidenbach, L. B., Fernandez, P. A., Leal, P. P., Noisette, F., McGraw, C. M., Revill, A. T., Hurd, C. L., & Kübler, J. E. (2017). Growth, ammonium metabolism, and photosynthetic properties of Ulva australis (Chlorophyta) under decreasing pH and ammonium enrichment. PLoS ONE, 12(11), e0188389. doi: 10.1371/journal.pone.0188389

Boyd, P. W., Dillingham, P. W., McGraw, C. M., Armstrong, E. A., Cornwall, C. E., Feng, Y.-y., Hurd, C. L., Gault-Ringold, M., Roleda, M. Y., … Nunn, B. L. (2016). Physiological responses of a Southern Ocean diatom to complex future ocean conditions. Nature Climate Change, 6, 207-213. doi: 10.1038/NCLIMATE2811

Roleda, M. Y., Cornwall, C. E., Feng, Y., McGraw, C. M., Smith, A. M., & Hurd, C. L. (2015). Effect of ocean acidification and pH fluctuations on the growth and development of coralline algal recruits, and an associated benthic algal assemblage. PLoS ONE, 10(10), e0140394. doi: 10.1371/journal.pone.0140394

Mendecki, L., Fayose, T., Stockmal, K. A., Wei, J., Granados-Focil, S., McGraw, C. M., & Radu, A. (2015). Robust and ultrasensitive polymer membrane-based carbonate-selective electrodes. Analytical Chemistry, 87(15), 7515-7518. doi: 10.1021/acs.analchem.5b01756

Cornwall, C. E., Boyd, P. W., McGraw, C. M., Hepburn, C. D., Pilditch, C. A., Morris, J. N., Smith, A. M., & Hurd, C. L. (2014). Diffusion boundary layers ameliorate the negative effects of ocean acidification on the temperate coralline macroalga Arthrocardia corymbosa. PLoS ONE, 9(5), e97235. doi: 10.1371/journal.pone.0097235

James, R. K., Hepburn, C. D., Cornwall, C. E., McGraw, C. M., & Hurd, C. L. (2014). Growth response of an early successional assemblage of coralline algae and benthic diatoms to ocean acidification. Marine Biology, 161(7), 1687-1696. doi: 10.1007/s00227-014-2453-3

Hoffmann, L. J., Breitbarth, E., McGraw, C. M., Law, C. S., Currie, K. I., & Hunter, K. A. (2013). A trace-metal clean, pH-controlled incubator system for ocean acidification incubation studies. Limnology & Oceanography: Methods, 11, 53-61. doi: 10.4319/lom.2013.11.53

Jones, K. N., Currie, K. I., McGraw, C. M., & Hunter, K. A. (2013). The effect of coastal processes on phytoplankton biomass and primary production within the near-shore Subtropical Frontal Zone. Estuarine, Coastal & Shelf Science, 124, 44-55. doi: 10.1016/j.ecss.2013.03.003

Cornwall, C. E., Hepburn, C. D., McGraw, C. M., Currie, K. I., Pilditch, C. A., Hunter, K. A., Boyd, P. W., & Hurd, C. L. (2013). Diurnal fluctuations in seawater pH influence the response of a calcifying macroalga to ocean acidification. Proceedings of the Royal Society B, 280, 20132201. doi: 10.1098/rspb.2013.2201

Radu, A., Radu, T., McGraw, C., Dillingham, P., Anastasova-Ivanova, S., & Diamond, D. (2013). Ion selective electrodes in environmental analysis. Journal of the Serbian Chemical Society, 78, 1729-1761. doi: 10.2298/JSC130829098R

Roleda, M. Y., Morris, J. N., McGraw, C. M., & Hurd, C. L. (2012). Ocean acidification and seaweed reproduction: Increased CO2 ameliorates the negative effect of lowered pH on meiospore germination in the giant kelp Macrocystis pyrifera (Laminariales, Phaeophyceae). Global Change Biology, 18(3), 854-864. doi: 10.1111/j.1365-2486.2011.02594.x

Cornwall, C. E., Hepburn, C. D., Pritchard, D., Currie, K. I., McGraw, C. M., Hunter, K. A., & Hurd, C. L. (2012). Carbon-use strategies in macroalgae: Differential responses to lowered pH and implications for ocean acidification. Journal of Phycology, 48(1), 137-144. doi: 10.1111/j.1529-8817.2011.01085.x

Law, C. S., Breitbarth, E., Hoffmann, L. J., McGraw, C. M., Langlois, R. J., LaRoche, J., … Safi, K. A. (2012). No stimulation of nitrogen fixation by non-filamentous diazotrophs under elevated CO2 in the South Pacific. Global Change Biology, 18(10), 3004-3014. doi: 10.1111/j.1365-2486.2012.02777.x

Dillingham, P. W., Radu, T., Diamond, D., Radu, A., & McGraw, C. M. (2012). Bayesian methods for ion selective electrodes. Electroanalysis, 24(2), 316-324. doi: 10.1002/elan.201100510

Hurd, C. L., Cornwall, C. E., Currie, K., Hepburn, C. D., McGraw, C. M., Hunter, K. A., & Boyd, P. W. (2011). Metabolically induced pH fluctuations by some coastal calcifiers exceed projected 22nd century ocean acidification: A mechanism for differential susceptibility? Global Change Biology, 17, 3254-3262. doi: 10.1111/j.1365-2486.2011.02473.x

Cummings, V., Hewitt, J., Van Rooyen, A., . . ., Gomez, A., McGraw, C., & Metcalf, V. (2011). Ocean acidification at high latitudes: Potential effects on functioning of the Antarctic bivalve Laternula elliptica. PLoS ONE, 6(1), e16069. doi: 10.1371/journal.pone.0016069

McGraw, C. M., Cornwall, C. E., Reid, M. R., Currie, K. I., Hepburn, C. D., Boyd, P., Hurd, C. L., & Hunter, K. A. (2010). An automated pH-controlled culture system for laboratory-based ocean acidification experiments. Limnology & Oceanography: Methods, 8, 686-694. doi: 10.4319/lom.2010.8.686

McGraw, C. M., Radu, T., Radu, A., & Diamond, D. (2008). Evaluation of liquid- and solid-contact, Pb2+-selective polymer-membrane electrodes for soil analysis. Electroanalysis, 20(3), 340-346.

Cleary, J. J., Slater, C., McGraw, C., & Diamond, D. (2008). An autonomous microfluidic sensor for phosphate: On-site analysis of treated wastewater. IEEE Sensors Journal, 8(5), 508-515.

McGraw, C. M., Khalil, G., & Callis, J. B. (2008). Comparison of time and frequency domain methods for luminescence lifetime measurements. Journal of Physical Chemistry C, 112(21), 8079-8084.

McGraw, C. M., Stitzel, S. E., Cleary, J., Slater, C., & Diamond, D. (2007). Autonomous microfluidic system for phosphate detection. Talanta, 71(3), 1180-1185. doi: 10.1016/j.talanta.2006.06.011

McGraw, C. M., Bell, J. H., Khalil, G., & Callis, J. B. (2006). Dynamic surface pressure measurements on a square cylinder with pressure sensitive paint. Experiments in Fluids, 40, 203-211. doi: 10.1007/s00348-005-0059-8

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Journal - Research Other

Hurd, C. L., Beardall, J., Comeau, S., Cornwall, C. E., Havenhand, J. N., Munday, P. L., … McGraw, C. M. (2020). Ocean acidification as a multiple driver: How interactions between changing seawater carbonate parameters affect marine life. Marine & Freshwater Research, 71, 263-274. doi: 10.1071/MF19267

Boyd, P. W., Collins, S., Dupont, S., Fabricius, K., Gattuso, J.-P., Havenhand, J., … McGraw, C. M., … Pörtner, H.-O. (2018). Experimental strategies to assess the biological ramifications of multiple drivers of global ocean change: A review. Global Change Biology, 24(6), 2239-2261. doi: 10.1111/gcb.14102

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Conference Contribution - Published proceedings: Full paper

Dillingham, P. W., Alsaedi, B. S. O., & McGraw, C. M. (2017). Characterising uncertainty in instrumental limits of detection when sensor response is non-linear. Proceedings of the IEEE Sensors Conference. (pp. 94-96). IEEE. doi: 10.1109/ICSENS.2017.8233898

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Conference Contribution - Published proceedings: Abstract

Dillingham, P. W., Hong, C. Y., Cornwall, C. E., Fletcher, D., McGraw, C. M., & Zeng, J. (2021). Multi-driver experiments with different scales of replication. Proceedings of the 14th Annual New Zealand Ocean Acidification Conference: Ocean Acidification in a Decade of Ocean Science. (pp. 13). Retrieved from http://nzoac.nz/conferences

Chen, D. W. H., & McGraw, C. (2019). Fibre optic pH microsensor for studying the impact of ocean acidification on the marine environment. Proceedings of the 12th New Zealand Ocean Acidification Workshop. (pp. 48). Retrieved from http://nzoac.nz

Seah, N., Law, C., & McGraw, C. (2019). Combatting the effects of ocean acidification on farmed molluscs. Proceedings of the 12th New Zealand Ocean Acidification Workshop. (pp. 51). Retrieved from http://nzoac.nz

Hashemi, S., Seah, N., Chen, D. W. H., Hermansson, A. L., Dillon, W., Currie, K., & McGraw, C. (2019). Refining low-cost carbonate ion selective electrodes for 2D profiling. Proceedings of the 12th New Zealand Ocean Acidification Workshop. (pp. 49). Retrieved from http://nzoac.nz

Dillon, W. D. N., Law, C. S., & McGraw, C. M. (2019). A deployable saturation state sensor towards global ocean monitoring. Proceedings of the 12th New Zealand Ocean Acidification Workshop. (pp. 29). Retrieved from http://nzoac.nz

Meyers, M., McGraw, C., Décima, M., & Hoffmann, L. (2019). Design and employment of a new portable CO2 system for ocean acidification experiments. Proceedings of the 12th New Zealand Ocean Acidification Workshop. (pp. 50). Retrieved from http://nzoac.nz

Lunde Hermansson, A., Dillon, W., Smith, A. M., Dillingham, P., & McGraw, C. (2019). Solubility of natural carbonate samples. Proceedings of the 12th New Zealand Ocean Acidification Workshop. (pp. 43). Retrieved from http://nzoac.nz

Law, C., Gall, M., Barr, N., McGraw, C., Dillon, W., Bianchi, M., … Farrington, G. (2019). Mitigating low pH for the mussel aquaculture industry. Proceedings of the 12th New Zealand Ocean Acidification Workshop. (pp. 26). Retrieved from http://nzoac.nz

McGraw, C. M., Havenhand, J. N., Fabricius, K. E., Dillingham, P. W., Hurd, C. L., & Boyd, P. W. (2018). Changing Ocean Biological Systems (COBS): How will biota respond to a changing ocean? Proceedings of the 11th New Zealand Ocean Acidification Workshop. (pp. 18). Retrieved from http://nzoac.nz

Dillon, W., Dillingham, P., Law, C., & McGraw, C. (2018). Development of an optical fibre based omega probe for calcium carbonate. Proceedings of the 11th New Zealand Ocean Acidification Workshop. (pp. 10). Retrieved from http://nzoac.nz

McGraw, C. M., Dillon, W. D. N., Doyle, H. L., Dillingham, P. W., Lye, P. G., Boyd, P. W., & Hurd, C. L. (2017). A multi-sensor system to monitor marine variability associated with global climate change. Proceedings of the 10th New Zealand Ocean Acidification Workshop. (pp. 23). Retrieved from http://www.otago.ac.nz/oceanacidification/news/index.html

Law, C., Barr, N., Stevens, C., Plew, D., Cummings, V., Hunter, K., Murdoch, J., & McGraw, C. (2017). A feasibility study of coastal acidification mitigation strategies for the mussel industry. Proceedings of the National Science Challenge Conference: Sustainable Seas. [Abstract]

Dillingham, P. W., Boyd, P. W., Hurd, C. L., Cornwall, C. E., & McGraw, C. M. (2017). The collapsed factorial: A small-factor experimental design for multi-stressor ocean acidification experiments. Proceedings of the 10th New Zealand Ocean Acidification Workshop. (pp. 15). Retrieved from http://www.otago.ac.nz/oceanacidification/news/index.html

Dillingham, P. W., Boyd, P. W., Hurd, C. L., Cornwall, C. E., & McGraw, C. M. (2016). Beyond ANOVA: Design and analysis of multi-stressor experiments. Proceedings of the 4th International Symposium on the Ocean in a High-CO2 World. Retrieved from http://www.highco2-iv.org/

McGraw, C. M., Dillon, W. D. N., Doyle, H. L., Dillingham, P. W., Lye, P. G., Boyd, P. W., & Hurd, C. L. (2016). A multi-sensor system for the direct measurement of Ω, pH, and carbonate. Proceedings of the 4th International Symposium on the Ocean in a High-CO2 World. Retrieved from http://www.highco2-iv.org/

Boyd, P. W., Armstrong, E., Dillingham, P., McGraw, C., Cornwall, C., & Hurd, C. L. (2016). Physiological diagnosis of a Southern Ocean diatom's responses to future complex ocean conditions. Proceedings of the 4th International Symposium on the Ocean in a High-CO2 World. Retrieved from http://www.highco2-iv.org/

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