Professor Mary A Sewell
PhD University of Alberta
Research | Current
My research focuses on reproduction and early development of marine invertebrates, with a focus on echinoderms. A central question to my research programme is how organisms achieve successful reproduction in different environments (e.g. in Antarctica and the deep sea), and how external factors such as temperature, salinity and anthropogenic climate change affect reproduction and development.
My research lab is located in the Extension of the Thomas Building (Building 110N, Level 1), though considerable research takes place outside Auckland – from the Leigh Marine Laboratory, to sites within the Hauraki Gulf, and as far afield as Antarctica.
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Echinoderm Reproduction and Development
Echinoderms have been the focus of my research since I was a graduate student - with both my Masters and PhD research on reproduction in a broadcast spawning (Australostichopus mollis) and a brooding species (Leptosynapta clarki) respectively. As a post-doctoral researcher I began to study starfish and sea urchins and now work broadly on reproduction in echinoderms.
A particular focus of my recent research has been on maternal investment in echinoderm eggs, and in particular in the protein and lipid content of species with both planktotrophic (feeding) and lecithotrophic development (non-feeding). My students and national and international collaborators use the School of Biological Sciences Iatroscan TLC/FID system to examine maternal provisioning of lipids in echinoderms and other marine invertebrates. These studies have shown that there are clear differences in the lipid classes and amounts of lipid in planktotrophs versus lecithotrophs, that lipids are rapidly used during early development of planktotrophs, and retained well after settlement in lecithotrophs.
The pelagic community of the Ross Sea consists of a permanent component (= holoplankton) and a temporary component which is primarily made up from the larval stages of benthic marine invertebrates and fish (= the meroplankton). To date little attention has been paid to the distribution and abundance patterns of the meroplankton in the Ross Sea in part because of the difficulty in identifying the larvae of marine invertebrates and fish to the species-level.
Traditionally identification of larvae to the species-level has relied on the time consuming and labour-intensive process of fertilizing eggs and culturing the larvae through to metamorphosis. In Antarctica, the low seawater temperatures and long developmental times make this procedure even more problematic than in temperate environments. With my collaborator Dr. Shane Lavery (SBS, University of Auckland) we have been using a molecular-based approach to match DNA sequences of the meroplankton with adult benthic marine invertebrates (Sewell et al. 2006; Heimeier et al. 2010).
Much of my Antarctic research was completed under the umbrella of the Latitudinal Gradient Project (LGP) where we worked at three sites along the Victoria Land Coast (Cape Hallett, Terra Nova Bay, Granite Harbour) to examine how the meroplankton community changes with the latitudinal gradient of solar radiation, temperature and sea ice cover (Gallego et al. 2015). We have also examined the coastal versus oceanic gradient using samples collected on New Zealand’s International Polar Year-Census of Antarctic Marine Life (IPY-CAML) Cruise (Gallego et al. 2014).
Ocean acidification (OA) has been described as “the other CO2 problem”, “global warming’s evil twin” and “a meltdown tinged with acid”. Given that one third of humanity’s emissions of carbon dioxide are absorbed by the world’s oceans, OA will be one of the most important stressors facing marine ecosystems of the future. . Under the OA conditions predicted by the Intergovernmental Panel on Climate Change (IPCC 2007), organisms with calcium carbonate skeletons (e.g. coccoliths, corals, molluscs, sea urchins) will suffer significantly from increased costs to the growth and maintenance of skeletal structures, and/or the dissolution of their skeletons.
OA has been shown to have immediate impacts on both the morphology and gene expression patterns in sea urchin larvae, most of which indicate a depressed metabolism (O’Donnell et al. 2010). A similar result was seen in the New Zealand sea urchin Evechinus chloroticus - here we took a systems biology approach, combining whole-organism measurements with studies of the transcriptome, proteome and metabolome in early stage larvae. Ongoing analyses are we undertook research to understand the mechanisms by which OA impacts fertilization, early development and metabolic rate, at the biochemical, cellular and whole-organism levels. We have recently expanded our OA studies to include green shell mussels and brittlestars.
Did you know that you might be contributing to marine pollution simply by washing your face? In recent research we have shown that the plastic particles in facial cleansers are so small that they have a good likelihood of travelling from your bathroom sink and into the ocean.
Blog interview on Marsden ocean acidification research: http://sciblogs.co.nz/iaq/2015/01/15/at-the-beach-meet-global-warmings-evil-twin/
Interview on Nine-to-Noon 25 Aug 2014 - on ocean acidification in Antarctica http://www.radionz.co.nz/national/programmes/ninetonoon/audio/20146961/ocean-acidification-in-antarctic-canary-in-the-coalmine-for-nz
- Blog-site interview, April 2 2010
- Highlighted on a number of plastics pollution and environmental web sites, e.g. on globalgarbage.org
- Was highlighted in an episode of “What’s Really In Our ....” (TV3) in the episode on soaps and cleansers. Episode aired August 17 2010.
Students interested in aspects of this research are encouraged to contact Dr. Mary Sewell for further information.
Teaching | Current
I contribute to teaching in the following courses:
- BIOSCI 208 Invertebrate Diversity (Course Co-ordinator)
- BIOSCI 333 Marine Ecology
- BIOSCI 724 Marine Ecology (Course Co-ordinator)
Students interested in aspects of my research are encouraged to contact Mary Sewell for further information.
Royal Society of New Zealand Expert Panel on Antarctic Sciences.
Technical Steering Committee of the US–New Zealand Joint Committee Meeting (JCM) on Science and Technology Cooperation: Marine and Ocean Research between NOAA and NIWA.
Areas of expertise
Ecology, Evolution and Behaviour
Selected publications and creative works (Research Outputs)
- Carroll, E. L., Gallego, R., Sewell, M. A., Zeldis, J., Ranjard, L., Ross, H. A., ... Constantine, R. (2019). Multi-locus DNA metabarcoding of zooplankton communities and scat reveal trophic interactions of a generalist predator. Scientific reports, 9 (1)10.1038/s41598-018-36478-x
Other University of Auckland co-authors: Emma Carroll, Rochelle Constantine
- Peters-Didier, J., & Sewell, M. A. (2019). The role of the hyaline spheres in sea cucumber metamorphosis: lipid storage via transport cells in the blastocoel. EvoDevo, 1010.1186/s13227-019-0119-4
- Chan, K. Y. K., Sewell, M. A., & Byrne, M. (2018). Revisiting the larval dispersal black box in the Anthropocene. ICES JOURNAL OF MARINE SCIENCE, 75 (6), 1841-1848. 10.1093/icesjms/fsy097
- Baker, D. W., Hudson, M. E., Frost, E. J., & Sewell, M. A. (2018). Repeated measurement of Mo2 in small aquatic organisms: a manual intermittent flow respirometer using off-the-shelf components. Journal of applied physiology (Bethesda, Md. : 1985), 124 (3), 741-749. 10.1152/japplphysiol.00771.2017
- Prowse, T. A. A., Sewell, M. A., & Byrne, M. (2017). Three-stage lipid dynamics during development of planktotrophic echinoderm larvae. Marine Ecology Progress Series, 583, 149-161. 10.3354/meps12335
- Gallego, R., Dennis, T., Basher, Z., Lavery, S., & Sewell, M. (2017). On the need to consider multiphasic sensitivity of marine organisms to climate change: A case study of the Antarctic acorn barnacle. Journal of Biogeography, 44 (10), 2165-2175. 10.1111/jbi.13023
Other University of Auckland co-authors: Shane Lavery
- Peters-Didier, J., & Sewell, M. A. (2017). Maternal investment and nutrient utilization during early larval development of the sea cucumber Australostichopus mollis. Marine Biology, 164 (9).10.1007/s00227-017-3209-7
- Sinclair, B. J., Marshall, K. E., Sewell, M. A., Levesque, D. L., Willett, C. S., Slotsbo, S., ... Helmuth, B. S. (2016). Can we predict ectotherm responses to climate change using thermal performance curves and body temperatures?. Ecology Letters, 19 (11), 1372-1385. 10.1111/ele.12686