Fred Andrus



  • PhD, Geology, The University of Georgia, 2000
  • MA, Anthropology, The University of Georgia, 1995
  • BA, Anthropology, The University of Georgia, 1990

Research Areas

  • Paleontology, Paleoclimatology, and Paleoecology


Research Interests

My research focuses on developing and applying proxies relevant to reconstructing paleoclimate variation, often in the Pleistocene and Holocene, but sometimes with more ancient fossils. Methodologically, I often interpret sclerochronological records of growth and biogeochemical 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.

clam valve
Micromilling a clam valve for geochemical analysis

Paleoclimate reconstructions:

Our group has projects in the Atlantic, Pacific, and Gulf Coast of North America, Central America, Pacific South America, Greenland, the Adriatic Sea, 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:

SCUBA divers wading near show, preparing to collect clams near Dutch Harbor, Alaska.
Christine Bassett (right) preparing to dive near Dutch Harbor, Alaska.

Upwelling proxies using radiocarbon and stable nitrogen isotopes

William Holland, current Randall Research Scholar, is measuring radiocarbon variation in Aleutian coralline algae influence by vertical mixing. Christine Bassett and I measured 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 (MS 2022) studied 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.

Freshwater mussel shell in cross-section showing growth increments (taken by Jamekia Durrough-Pritchard).

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, (MS 2023) analyzed rhodoliths from the Flower Garden Banks to better understand how such reefs form and are impacted by human activity and sea level rise. William Holland (BS Geology major and Randall Research Scholar) is analyzing radiocarbon from Aleutian Islands algae samples to measure the local radiocarbon reservoir effect, which will improve age-dating in the region and may relate reservoir flux to the Pacific Decadal Oscillation.

Midden Geoarchaeology

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. Most recently, MS student Teresa Dominguez is validating isotopic records of water temperature and salinity in Ostea edulis oyster shells from Croatia with the hope of applying these measurements to Neolithic sites in the region.

Selected Publications

Selected publications of the past 10 years. Highlighted text links to complete articles through institutional repositories or open access journals. * Denotes student author.