- PhD, Geology, The University of Georgia, 2000
- MA, Anthropology, The University of Georgia, 1995
- BA, Anthropology, The University of Georgia, 1990
- Paleontology, Paleoclimatology, and Paleoecology
My research focuses on developing and applying proxies relevant to reconstructing paleoclimate variation, often in the Pleistocene and Holocene, but sometime with more ancient fossils. Methodologically, I often measure isotopic and elemental data by microsampling carbonate skeletons. This may include mollusk shells, coralline algae, and fish otoliths. I have a particular interest in reconstructing how climate and environmental factors influence organisms, including humans. This approach often necessitates the investigation of the life history of organisms that may act as paleoclimate indicators and the use of archaeological remains as a source of paleoenvironmental data.
Our group has projects in the Atlantic, Pacific, and Gulf Coast of North America, Central America, Pacific South America, Greenland, and Antarctica. We assess past water temperature, rainfall/flood patterns, El Niño variability, and sea ice and glacier flux. Most recently, Ph.D. candidate Christine Bassett (MS, 2016) is analyzing modern and ancient clam shells from the Aleutian Islands. Her dissertation is a key part of the Unalaska Sea Ice Project with colleagues at Boston and Western Washington Universities. The goal of the project is to determine past variation in seasonal climate that may be related to the former extent of sea ice, and how such change affected people in the past. You can learn more about it on this website: http://www.bu.edu/articles/2017/dutch-harbor-middens/
Upwelling proxies using radiocarbon and stable nitrogen isotopes
Christine Bassett and I are developing stable nitrogen isotope records in Pacific abalone from the Chanel Islands, California as a possible upwelling and productivity proxy. Prior to that, I conducted upwelling-related research in coastal Peru for a number of years with several students and colleagues. Miguel Etayo (Ph.D. 2010), Christie Jones (MS 2010), and I measured radiocarbon profiles in various species of mollusks from the coast of Peru to better understand past and present upwelling and radiocarbon reservoir effects associated with El Niño/Southern Oscillation (ENSO).
Skeletal growth and biomineralization
My students and I study the ways skeletons and shells form (biomineralogy) and determine the factors that control their growth and biogeochemistry records over time (sclerochronology). For example, Gözde Degirman (current MS student) is studying growth patterns and stable isotope variation in Cretaceous ammonite fossils. Christie Jones (MS 2010) and Jiexin Wei (MS 2014) investigated the utility of geochemical records measured in Peruvian Semele corrugata, Choromytilus chorus, and Aulacomya ater shells as climate proxy data sources. We also study Crassostrea virginica, Mercenaria spp., Pachychilus spp., Haliotis cracherodii, Atlantic & Pacific Donax spp., Rangia cuneata, Trachycardium procerum, Protothaca aspermia, Saxidomus gigantea, various Unionid mussels, and otoliths from many fish.
Pollution records measuring nitrogen isotopes in mollusks
Nitrogen isotopes in mollusk shells can help track how sewage and agricultural waste levels changed over time in various bodies of water. Jestina Hansen (MS 2011) focused on refining different analytical methods. With colleagues at Dauphin Island Sea Lab (DISL) we measured nitrogen over time along the Alabama coast. Heather Black (MS 2014) measured prehistoric N isotpe variation in ancient and modern oyster shells from the Chesapeake Bay area and showed that humans began polluting it by the early 1800’s. Taylor Payne (MS 2016) conducted a similar study in the Charleston, SC harbor area. Current MS student Jamekia Durrough-Pritchard is comparing nitrogen isotope records in freshwater mussels from two river systems with different levels of agricultural impact.
Coralline algae paleoclimate research
Hillary Sletten, (Ph.D. 2016) developed and applied climate/environment proxies in coralline algae. She was awarded a fellowship to conduct research in Panama through the Smithsonian Tropical Research Institute where she collected rhodoliths and performed controlled mesocosm experiments. She also analyzed geochemistry in encrusting algae from Greenland to detect glacier melt. Sarah Olmstead, a current MS student, is beginning analysis of rhodoliths from the Flower Garden Banks to better understand how such reefs form and are impacted by human activity and sea level rise. We also hope to use algae geochemistry from the Aleutian Islands to measure the local radiocarbon reservoir effect, which will improve age-dating in the region.
We work with colleagues across North and South America using mollusk geochemistry, growth, biogeography, and related techniques to study shell middens. Our goals are often to assess past human subsistence strategies, season of occupation and resource use, site formation processes, and other questions relating to archaeology.
Selected publications of the past 10 years. Highlighted text links to complete articles through institutional repositories or open access journals. * Denotes student author.
- Colcasure, C. B., Andrus, C. F. T, and Blair, E. H., 2023. Of missions and marshes: stable isotope analysis of Mission-era Guale oyster harvesting seasonality on St. Catherines Island, Georgia. Journal of Island & Coastal Archaeology. 10.1080/15564894.2023.2192015.
- Hadden, C. S., Waselkov, G. A., Reitz, E. J., and Andrus C. F. T., 2022 Temporality of fishery taskscapes on the north-central Gulf of Mexico coast (USA) during the Middle/Late Woodland Period (AD 325–1040). Journal of Anthropological Archaeology. 67: 10.1016/j.jaa.2022.101436.
- Garland, C. J., Thompson, V. D., Sanger, M. C., Smith, K, Y., Andrus, C. F. T., Lawres, N. R., Napora, K. G., Colaninno, C. E., Compton, M. J., Jones, S., Hadden, C. S., Cherkinsky, A., Maddox, T., Deng, Y-T., Lulewicz, I. H., Parsons, L. 2022. A multi-proxy assessment of the impact of climate change on Late Holocene (ca 4500-3800 BP) Native American villages of the Georgia coast. PLoS ONE 17(3): e0258979. 10.1371/journal.pone.0258979.
- Mays, J. R., DeWitt, T. J., Dharampall, P., Andrus, C. F. T., and Findlay, R. H. 2021 Frequent habitat migration, phenotypic plasticity, and vestigial ecophenotypy revealed by isotope based natal habitat inference in bluegill sunfish, Lepomis macrochirus. Evolutionary Ecology Research. 2021.XII.6.
- Warner, J. P., DeLong, K. L., Chicoine D., Thirumalai, K, and Andrus, C. F. T. 2021 Investigating the influence of temperature and seawater δ18O on Donax obesulus (Reeve, 1854) shell δ18O. Chemical Geology. 588: 120638. 10.1016/j.chemgeo.2021.120638.
- Reitz, E. J., Hadden, C. S., Waselkov, G. A., and Andrus C. F. T., 2021 Woodland-period fisheries on the north-central coast of the Gulf of Mexico. Southeastern Archaeology. 10.1080/0734578X.2021.1922214.
- Bassett*, C. N., and Andrus, C. F. T., 2021 Examining the potential of Pacific abalone as a novel high-resolution archive of upwelling in the California Current. Palaeogeography, Palaeoclimatology, Palaeoecology. 10.1016/j.palaeo.2021.110342.
- Trofimova, T., Alexandroff, S., Mette, M., Tray, E., Butler, P., Campana, S., Harper, E., Johnson, A., Morrongiello, J., Peharda Uljevic, M., Schöne, B. R., Andersson, C., Andrus, C. F. T., Black, B., Burchell, M., Carroll, M., DeLong, K., Gillanders, B., Grønkjær, P., Killam, D., Prendergast, A., Reynolds, D., Scourse, J., Shirai, K., Thebault, J., Trueman, C., and de Winter., N. J., 2020. Fundamental questions and applications of sclerochronology: community-defined research priorities. Estuarine, Coastal and Shelf Science. 245: 106977. 10.1016/j.ecss.2020.106977
- Fodrie J., Heck K. L., Andrus C. F. T., and Powers S. P. 2020. Determinants of the nursery role of seagrass meadows in the sub-tropical Gulf of Mexico: inshore-offshore connectivity for snapper and grouper. Marine Ecology Progress Series. 647: 135–147. 10.3354/meps13403.
- Totten, R. L., Parker, L.E., Wallace, D. J., Lambert, W. J., Elliot, E. A., Andrus C. F. T., Lehrmann, A, A. 2020. A 7,000-year record of floods and ecological feedbacks in Weeks Bay, Alabama, USA. Science of the Total Environment. 73. 10.1016/j.scitotenv.2020.140052.
- Sandweiss, D. H., Andrus, C. F. T., Kelley, A. R., Maasch, K. A., Reitz, E. J., and Roscoe, P. B. 2020. Archaeological climate proxies and the complexities of reconstructing Holocene El Niño in coastal Peru. Proceedings of the National Academy of Sciences. 10.1073/pnas.1912242117.
- Collins, J., Scott, R. S., Andrus, C. F. T., Moe-Hoffman, A., and Peacock, E., 2019 Refit and Oxygen Isotope Analysis of Freshwater Mussel Shells from the Tillar Farms Site (3DR30), Southeast Arkansas. Midcontinental Journal of Archaeology. 10.1080/01461109.2019.1677999.
- Gillikin, D., Wanamaker, A.D., and Andrus, C. F. T., 2019 Chemical Sclerochronology. Chemical Geology. 10.1016/j.chemgeo.2019.06.016.
- Zimmt, J. B., Lockwood, R., Andrus, C. F. T., and Herbert, G. S., 2019 Sclerochronological basis for growth increment counting: a reliable technique for life-span determination of Crassostrea virginica from the Mid-Atlantic United States. Palaeogeography, Palaeoclimatology, Palaeoecology. 516: 54-63. 10.1016/j.palaeo.2018.11.029.
- Etayo-Cadavid*, M. F., Andrus, C. F. T., Jones, K. B., and Hodgins, G. W. L. 2018. Subseasonal variations in marine radiocarbon reservoir age from pre-bomb Donax obesulus and Protothaca asperrima shell carbonate. Chemical Geology. 10.1016/j.chemgeo.2018.07.001.
- Bassett*, C., Andrus, C. F. T., and West, C. F. 2018. Implications for measuring seasonality in the marine bivalve, Saxidomus gigantea. Chemical Geology. 10.1016/j.chemgeo.2018.07.004.
- West, C. F., Burchell, M., and Andrus, C. F. T. 2018. Molluscs and paleoenvironmental reconstruction in island and coastal settings: variability, seasonality, and sampling. In Giovas, C. M., and LeFebre, M. J., eds. Zooarchaeology in Practice: Case Studies in Methodology and Interpretation in Archaeofaunal Analysis. Springer. Cham, Switzerland p.191-208.
- Lulewicz, I. H., Thompson, V. D., Pluckhahn, T. J., Andrus, C. F. T., and Das, O. 2017. Exploring oyster (Crassostrea virginica) habitat collection via oxygen isotope geochemistry and its implications for ritual and mound construction at Crystal River and Roberts Island, Florida. Journal of Island and Coastal Archaeology. 13:3, 388-404. doi: 10.1080/15564894.2017.1363096.
- Wei*, J., Andrus, C. F. T., and Perez-Huerta, A., 2017. Semele corrugata microstructure and oxygen isotope profiles as indicators of seasonality. in Dillehay, T. D., ed. Where the Land Meets the Sea: Fourteen Millennia of Human Prehistory on the North Coast of Peru. University of Texas Press. Austin, TX. p.714-722.
- Sletten*, H. R., Gillikin, D. P., Halfar, J., Andrus, C. F. T., and Guzman, H. 2017. Skeletal growth controls on Mg/Ca and P/Ca ratios in tropical Eastern Pacific rhodoliths (coralline red algae). Chemical Geology. 465: 1-10. doi: 10.1016/j.chemgeo.2017.05.010.
- Black*, H. D., Andrus, C. F. T., Lambert, W. J, Rick, T., and Gillikin, D. P., 2017. δ15N values in Crassostrea virginica shells provides earliest direct evidence for nitrogen loading to Chesapeake Bay. Scientific Reports. 7: 44241; doi: 10.1038/srep44241.
- Sletten*, H. R., Andrus, C. F. T., Guzman, H. and Halfar, J., 2017. Re-evaluation of using rhodolith growth patterns for paleoenvironmental reconstruction: An example from the Gulf of Panama. Palaeogeography, Palaeoclimatology, Palaeoecology. 465: 264–277.
- Darrow, E. S., Carmichael, R. H., Andrus, C. F. T, and Jackson, E. H., 2017. From middens to modern estuaries, oyster shells sequester source-specific nitrogen. Geochimica et Cosmochimica Acta. 202: 39–56.
- Waselkov, G. A., Andrus, C. F. T, and Plumb, G. E.,eds. 2016. A State of Knowledge of the Natural, Cultural, and Economic Resources of the Greater Mobile-Tensaw River Area. Natural Resources Report NPS/NRSS/BRD/NRR 2016/1243. Biological Resources Division, National Park Service, Fort Collins, CO. pp.240.
- Plumb, G. E., Waselkov, G. A., Andrus, C. F. T., and Finch B., 2016. A greater Mobile-Tensaw area: connections and consequences. In Waselkov, G. A., Andrus, C. F. T, and Plumb, G. E., eds. A State of Knowledge of the Natural, Cultural, and Economic Resources of the Greater Mobile-Tensaw River Area. Natural Resources Report NPS/NRSS/BRD/NRR 2016/1243. Biological Resources Division, National Park Service, Fort Collins, CO. p. 185-193.
- Gagnon, C. M., Andrus, C. F. T., Ida, J., and Richardson, N. 2015, Local water source variation and experimental chicha de maíze brewing: implications for interpreting human hydroxyapatite δ18O values in the Andes. Journal of Archaeological Science: Reports. 4: 174–181.
- Thompson, V. D., Pluckhahn, T. J., Das, O. and Andrus, C. F. T. 2015, Assessing village life and monument construction (cal. AD 65-1070) along the Central Gulf Coast of Florida through stable isotope geochemistry. Journal of Archaeological Science: Reports. 4: 111–123.
- Blitz, J, H., Andrus, C. F. T., and Downs, L. 2014, Sclerochronological measures of seasonality at a Late Woodland mound on the Mississippi Gulf Coast. American Antiquity 79: 697-711.
- Etayo-Cadavid*, M. F., Andrus, C. F. T., Jones, K. B., Hodgins, G. W. L., Sandweiss, D. H. Uceda-Castillo, S., and Quilter, J. 2013. Marine radiocarbon reservoir age variation in Donax obesulus shells from Northern Peru: Late Holocene evidence for extended El Niño. Geology 41: 599–602.
- Pérez-Huerta, A. Etayo-Cadavid, M. F., Andrus, C. F. T., Jeffries, T. E., Watkins, C., Street, S. C., and Sandweiss, D. S. 2013 El Niño impact on mollusk biomineralization – Implications for trace element proxy reconstructions and the paleo-archeological record. PLoS ONE 8: e54274.
- Andrus C. F. T. 2012. Isotope sclerochronology in southeastern US archaeology to estimate season of capture. in Reitz, E. J, Quitmyer, I. R., and Thomas, D. H. eds. Seasonality and Human Mobility Along the Georgia Bight. American Museum of Natural History Anthropological Papers 97: 123-133 .