I am a marine scientist trying to understand how environmental conditions drive ecological patterns of fish and fisheries through a physiological lens. The goal is to generate knowledge that can be incorporated into fisheries management frameworks to enhance resource sustainability. I earned my PhD at the Department of Ichthyology and Fisheries Science, Rhodes University under the supervision prof. Warren Potts in the SAFER lab, Dr Nikki James and Dr Amanda Bates in the Physiological Diversity Lab at Southampton University. I subsequently did a postdoc with the South African Institute for Aquatic Biodiversity where I helped coordinate multiple research projects across southern Africa. I am currently based at Stanford University, working in Prof. Erik Sperling's Historical Geobiology Lab and Prof. Fio Micheli's lab at Hopkins Marine Station. During this postdoc I will use physiological models to predict climate impacts and identify spatial refugia of key California fishery species including Red Abalone and Purple Urchin.

Stanford Advisors

Lab Affiliations

All Publications

  • Marine Heatwaves Exceed Cardiac Thermal Limits of Adult Sparid Fish (Diplodus capensis, Smith 1884) FRONTIERS IN MARINE SCIENCE Van Der Walt, K., Potts, W. M., Porri, F., Winkler, A. C., Duncan, M., Skeeles, M. R., James, N. C. 2021; 8
  • Thermal tolerance, safety margins and vulnerability of coastal species: Projected impact of climate change induced cold water variability in a temperate African region. Marine environmental research van der Walt, K., Porri, F., Potts, W. M., Duncan, M. I., James, N. C. 2021; 169: 105346


    Anthropogenic induced climate change is predicted to increase the thermal variability in coastal waters, which can have strong physiological effects on individuals and populations of marine ectotherms. The magnitude and direction of these thermal effects varies depending on species, life stage, biogeography, habitat and season. This study aimed to compare the thermal tolerance of a range of juvenile fish and adult macro-invertebrates from intertidal and estuarine habitats in a warm-temperate, thermally variable region on the south-east coast of South Africa. Seasonal variability in thermal tolerance was compared between species, taxonomic groups, biogeographical distribution and habitat affinity and related to existing and projected water temperature data to gauge the local vulnerability of each species. Critical thermal maximum (CTmax), critical thermal minimum (CTmin), thermal breadths and scopes, and the thermal safety margins of each species were quantified. The greatest differences in thermal tolerance patterns were based on taxonomy, with macro-invertebrates having broader thermal tolerance compared to fish, with the exception of the Cape sea urchin, in both summer and winter. Relatively narrow lower breadths in tolerance and safety margin values for transient juvenile sub-tropical and temperate fish species from the intertidal rocky low-shore habitat were observed in both summer and winter. This indicates that these fish species and the Cape sea urchin may be more vulnerable to projected increases in cold temperature (upwelling in summer) than warm temperature variability in this warm-temperate region if they are unable to seek thermal habitat refuge.

    View details for DOI 10.1016/j.marenvres.2021.105346

    View details for PubMedID 33971581

  • Do contemporary age-growth models overlook life-history complexities in protandrous fishes? A case study on the large protandrous polynemid, the giant African threadfin Polydactylus quadrifilis FISHERIES RESEARCH Butler, E. C., Childs, A., Milner, M., Farthing, M. W., Duncan, M., Winkler, A. C., Potts, W. M. 2021; 233
  • Different drivers, common mechanism; the distribution of a reef fish is restricted by local-scale oxygen and temperature constraints on aerobic metabolism CONSERVATION PHYSIOLOGY Duncan, M., James, N. C., Potts, W. M., Bates, A. E., Cooke, S. 2020; 8
  • Understanding the effects of recreational catch-and-release angling on an increasingly important foreign fishing tourism species, the giant African threadfinPolydactylus quadrifilis(Cuvier) FISHERIES MANAGEMENT AND ECOLOGY Butler, E., Childs, A., Duncan, M., Potts, W. 2020

    View details for DOI 10.1111/fme.12451

    View details for Web of Science ID 000552504200001