John F. Valentine

Senior Marine Scientist
Chair of University Programs, DISL
Professor of Marine Science
University of South Alabama

Ph.D., 1989, University of Alabama

Email

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. Newly funded work will examine 1) the degree to which marine production can subsidize the diets adult freshwater piscivorous fishes in oligohaline vegetated habitats in the northern Gulf of Mexico, 2) the relative value of infaunal functional groups to demersal fish growth, also in the northern Gulf of Mexico and 3) the indirect effects of the removal of large predatory fishes on the base of seagrass food webs in the Florida Keys. Finally, one planned project will be to investigate the degree to which seagrass detritus can subsidize the productivity of macroinvertebrates in nearby unvegetated habitats.

The overall significance of this research lies in its attempt to understand the processes that control the distribution and productivity of submerged vegetated habitats throughout the western Atlantic Ocean. Because of the widespread occurrence of these habitats, the extraordinary productivity and richness of their associated biota, an understanding of the factors controlling their distribution and the degree to which they subsidize the productivity of nearby less productive habitats is essential to our understanding of how the overall productivity of nearshore waters is determined. 

Martin, C. M. and J. F. Valentine. In press. Impacts of a habitat-forming exotic species on estuarine structure and function: an experimental assessment of eurasian milfoil. Estuaries and Coasts.

Chaplin, G., and J. F. Valentine. 2009. Secondary production of macroinvertebrates in the tidal influenced Mobile Bay Delta. Estuaries and Coasts 32:319-332.

Goecker, M., J. F. Valentine, S. S. Sklenar and G. Chaplin. 2009. Influence from hydrological modification on energy and nutrient transference in a deltaic food web. Estuaries and Coasts. 32: 173-187.

Valentine, J. F., K. L. Heck, M. Dardeau and Hank Burch. In press. Ecosystem-based management of Mobile Bay, Alabama.  In: The Gulf of Mexico: Its Origins, Waters, Biota & Human Impacts. Volume V: The Gulf of Mexico: Ecosystem-Based Management. J. Day and A. Yanez-Arancibia. Texas A & M University Press.

Valentine J. F., K. L.Heck, Jr., D. Blackmon, B. J. Peterson, M. E. Goecker, J. Christian, R. M. Kroutil, M. A. VanderKlift , K. D. Kirsch, and M. Beck. 2008. Exploited species impacts on trophic linkages along reef-seagrass interfaces in the Florida Keys.  Ecological Applications 18:1501-1515.

Park, K., J. F. Valentine, K. R. Weis, and M. R. Dardeau. 2007. Effects of Hurricane Ivan on Mobile Bay, Alabama. Journal of Coastal Research 23:1332-1336.

Heck, K. L., and J. F. Valentine. 2007. The primacy of consumers in benthic ecosystems of the coastal zone. Estuaries and Coasts 30:371-381.

Vanderklift, M. A., J. How, T. Wernberg, L. D. MacArthur,  K. L. Heck, Jr ,and J. F. Valentine. 2007.  Proximity to reef influences the density of small predatory fishes while type of seagrass influences intensity of predation on crabs.  Marine Ecology Progress Series 340:235-243.

Fioravanti. G. and J. F. Valentine. 2007.  Impacts of reef architecture and fishing on food webs in back reef environments of the upper Florida Keys national marine sanctuary. Florida Scientist 70:120-136

Valentine, J. F., K. L.Heck, Jr., D. Blackmon, M. E. Goecker, J. Christian, R. M. Kroutil, K. D. Kirsch, B. J.  Peterson, M. Beck and M. A.Vanderklift. 2007. Food web interactions along seagrass-coral reef boundaries: An experimental test of the impacts of piscivore reductions on cross-habitat energy exchange using the marine protected areas of the Florida Keys National Marine Sanctuary Marine Ecology Progress Series 333:37-50.

Goecker, M.,  J. F. Valentine and S. Sklenar. 2006. Efftects of exotic submerged aquatic vegetation on waterfowl in the Mobile-Tensaw Delta.  Gulf of Mexico Science 24:68-80.

Heck, K. L. and J. F. Valentine.  2006.  Plant - Herbivore interactions in seagrass meadows.  Journal of Experimental Marine Biology and Ecology 330:420-436.

Heck, K. L., J. F. Valentine, J. R. Pennock, G. Chaplin and P. M. Spitzer. 2006. How herbivores can mediate the effects of nutrient enrichment on seagrass meadows: unexpected results of a field experiment.  Marine Ecology Progress Series 326:145-156.

Valentine, J. F. and J. Emmett Duffy. 2006. The Central Role of Grazing in Seagrass Ecology. Pp. 463-501 In: "Seagrass: Biology, Ecology and their Conservation" T. Larkum, R. Orth and C. Duarte (eds.) Springer.

Valentine, J. F. and K. L. Heck, Jr.  2005. Interaction strength at the coral reef-seagrass interface: has overfishing diminished the importance of seagrass habitat production for coral reef food webs? Coral Reefs 24:209-213.

Goecker, M. E., K. L. Heck, Jr. and J. F. Valentine. 2005. Effects of nitrogen content in turtlegrass, Thalassia testudinum, on consumption by the bucktooth parrotfish, Sparisoma radians.  Marine Ecology Progress Series 286:239-248.

Selected Current Research Grants

Alabama Oyster Restoration Program. Pending Impacts of restoring habitat diversity and site selection on ecosystem structure and function: and experimental assessment. 2007-2009

NOAA-NURC. Marine Reserve Effectiveness in Restoring Coastal Food Webs: A Multitrophic Assessment Using Special Protection Areas in the Florida Keys National Marine Sanctuary. 2007-2008

NOAA-CIAP. Assessments of Hurricane Katrina Impacts on the lower Mobile-Tensaw Delta. 2008-2009