Dr. John Valentine

Dr. John Valentine

Marine Sciences


  • Professor, University of South Alabama
  • Executive Director, Dauphin Island Sea Lab
  • Ph.D. 1989, University of Alabama

Emphasis: Experimental Marine Ecology, Plant-animal interactions, Habitat Linkages, Human-Dominated Ecosystems.

Research Interests

My current research interests examine the role of biotic processes, and human perturbations, in controlling the flow of energy among trophic levels both within and between marine habitats, with emphasis on submerged vegetated habitats. This research is being conducted in diverse locations ranging from the lower reaches of the Mobile Bay Delta to the Marine Protected Areas of the northern Florida Keys. Much of the emphasis of this work is on:

  1.  experimental assessments of grazing intensity in seagrass habitats,
  2.  responses of seagrasses to this grazing, and
  3.  the role of omnivory in controlling trophic cascades in marine systems.
See More

Selected Current Research Grants

  • Lead PI - Alabama Center for Ecological Resilience. Gulf of Mexico Research Initiative (2015-2018). - $6,497,054

  • Food & Drug Administration (FDA) and MESC/Dauphin Island Sea Lab Collaboration - $790,000

  • National Science Foundation - "Collaborative Proposal: Gulf Coast ADVANCE:  Cross Institutional Synergy for Women Scientist - $44,652.00


  • Valentine, J.F. and K. L. Heck, Jr. Herbivory in Seagrass Meadows: an Evolving Paradigm. Estuaries and Coasts (2020). https://doi.org/10.1007/s12237-020-00849-3

  • Martin, C.W., K.A Lewis, A.M. McDonald, T.P. Spearman, S.B. Alford, R.C. Christian, and J.F. Valentine. Disturbance-driven changes to northern Gulf of Mexico nekton communities following the Deepwater Horizon oil spill: evidence for the need for expanded coastal monitoring systems. Marine Pollution Bulletin. 155: 111098. DOI: 10.1016/j.marpolbul.2020.111098.

  • Martin, C.W. and J.F. Valentine. Invasion of Eurasian Milfoil Myriophyllum spicatum Lead to a “Trophic Dead End” and Reduced Food Web Complexity in Gulf of Mexico Estuarine Food Webs? Front. Environ. Sci. doi.org/10.3389/fenvs.2019.00166

  • Seubert, E.A., N.E. Hussey, S.P. Powers, J.F. Valentine, and J.M. Drymon. Assessing trophic flexibility of a predator assemblage across a large estuarine seascape using blood plasma stable isotope analysis. Food Webs. In Press.

  • Martin, C.W. and J.F. Valentine. Eurasian milfoil in Gulf of Mexico estuaries: does invasion of complex submerged vegetation lead to a “trophic dead end” in estuarine food webs? PeerJ Preprints. 6:e27454v1. doi.org/10.7287/peerj.preprints.27454v1.

  • Kauffman, T.C., C.W. Martin, and J.F. Valentine. Hydrological alteration exacerbates the negative impacts of invasive Eurasian milfoil Myriophyllum spicatum by creating hypoxic conditions in a northern Gulf of Mexico estuary. Marine Ecology Progress Series. 592: 97-108.

  • Bearden, B., J. Valentine, P. O'Neil, and S. Jones. Emerging Water Policy Issues in Coastal Alabama. The Wave. Volume 37. Number 3. 15-23.

  • Steele, L. and J. Valentine. 2015. Seagrass deterrence to mesograzer herbivory: evidence from mesocosm experiments and feeding preference trials. Marine Ecology Progress Series. 524: 83-94.

  • Martin, C.W., and J.F. Valentine. 2014. Tolerance of Embryos and Hatchlings of the Invasive Apple Snail Pomacea maculata to Estuarine Conditions. Aquatic Ecology 48: 321-326.

  • Martin, C.W., and J.F. Valentine. 2014. Sexual and asexual reproductive strategies of invasive eurasian milfoil (Myriophyllum spicatum) in estuarine environments. Hydrobiologia. 727: 177-184.

See More