Research Interests (Global Research Projects: 1, 2)

My research has focused on three major areas: microbial mediation of biogeochemical process (particularly carbon cycling), trophic interactions among microorganisms (bacteria, protozoans, algae and viruses), and microbial biofouling. I am especially interested in microbiological and chemical exchange processes across interfaces, such as oxic/anoxic, sediment/water and air/water boundaries.

One of my enduring research interests has been the diagenesis and microbial ecology of organic debris as it is transported from sites of production to sites of deposition. Flux and decomposition of this material in the ocean has important implications on nutrient cycling, ocean productivity, transport of contaminants, and the ocean's capacity to sequester atmospheric carbon dioxide in its interior (deep water and sediments). Microbiological processes are intimately linked to the fate of this carbon. As part of the NSF-funded CARIACO Time Series Program (CArbon Retention In AColored Ocean), we are improving our understanding of current carbon cycling dynamics in the Cariaco Basin on the continental margin of Venezuela (Caribbean Sea). Our results are being used to better interpret ocean conditions and climate in the geologic past in order to better predict the future. To learn more about this program, visit its website (http://www.imars.marine.usf.edu/CAR/) or refer to some of the publications listed below.

My lab and Prof. M. Scranton’s lab are focusing on biogeochemistry, microbial dynamics and transformations of organic materials transported to the redoxcline (transition between oxic and anoxic waters).  We are particularly keen to understand processes that control chemoautotrophic production within the redoxcline.  The reason being that chemoautotrophic carbon fixation has been a significant fraction of primary production in overlying waters during some of our observations.  In addition to our times series program, we and colleagues from several other institutions have added two NSF-sponsored Microbial Observatories to the CARIACO core program, one focusing on prokaryotes and the other on microbial eukaryotes.  In these programs, we combine geochemical and traditional microbial ecological measurements with modern molecular techniques (ssu rRNA libraries, T-RFLP, DGGE, FISH, microautoradiography-FISH, etc.) to unravel the interplay between chemical gradients, elemental cycling and microbial population dynamics.  Our findings will likely have broader application to other anoxic systems, such as fjords, stratified basins and sediments.

For the last 40 years, studies on nutrient limitation of phytoplankton have primarily focused on nitrogen, phosphorus, silicon, and most recently on iron, but have largely ignored organic micronutrients, particularly coenzymes like B-vitamins.  Many phytoplankton species that are important in the ocean’s biological carbon pump are incapable of biosynthesizing one or more of the essential B-vitamins.  Therefore uptake of exogenous B-vitamins is required for their growth.  This is a very interesting example of ecological adaptation whereby some phytoplankton taxa have evolved to rely on external sources of a class of organic nutrient that is presumably produced mostly by bacteria.  With Prof. S. Sañudo-Wilhelmy, we are exploring the cycling of exogenous B-vitamins through field observations of a wide range of oceanographic regimes and by experimentation to better understand the influence of B-vitamins on phytoplankton community dynamics. 

Presence of human viruses in commercial shellfish and recreational waters that test negative for sewage proxies (fecal coliforms and enterocooci bacteria) suggests that water quality surveillance methods may be insufficient to prevent waterborne and foodborne disease transmission to human consumers of coastal resources.  We recently embarked on a NOAA-funded (Oceans and Human Health Initiative) project to investigate fundamental oceanographic processes regulating loss and decay of viruses in the coastal ocean.  Processes such as sorption to particles and unreceptive hosts, spontaneous disintegration, enzymatic decay and solute sorption to viruses are under scrutiny.  Project combines field and laboratory experiments to evaluate processes removing and degrading viruses upon introduction to the coastal ocean.  A unique aspect is that we are collaborating with several virology labs on campus to assess infective titers of common human viruses (enteroviruses, adenoviruses, rotaviruses, etc.) in environmental samples as well as quantifying their gene copies using real-time PCR.  Our long-term goal is to develop mechanistic models to guide future surveillance strategies and suggest mitigation approaches.

Selected Recent Publications

Lin X, Scranton MI, Varela R, Chistoserdov A & Taylor GT (submitted) Compositional responses of bacterial communities to redox gradients and grazing in the anoxic Cariaco Basin. Aquat. Microb. Ecol.

Lin X, Wakeham SG, Putnam IF, Astor YM, Scranton MI & Taylor GT(2006) Vertical distributions of prokaryotic assemblages in the anoxic Cariaco Basin and Black Sea compared using fluorescent in situ hybridization (FISH). Appl. Environ. Microbiol. 72(4): 2679-2690

Sañudo-Wilhelmy, SA, Okbamichael M, Gobler CJ & Taylor GT(2006) Regulation of phytoplankton dynamics by vitamin B₁₂. Geophys. Res. Letters. 33, L04604, doi:10.1029/2005GL025046

Taylor GT, Gobler CJ & Sañudo-Wilhelmy SA (2006) Speciation and concentrations of dissolved nitrogen as determinants of brown tide (Aureococcus anophagefferens) bloom initiation. Mar. Ecol. Prog. Ser. 312:67-83

Stoeck T, Hayward B, Taylor GT, Varela R, Epstein SS (2006) The multiple PCR-primer approach to access the microeukaryotic diversity in the anoxic Cariaco Basin (Caribbean Sea). Protist 157: 31-43

Taylor GT, Iabichella-Armas M, Varela R, Muller-Karger F, Lin X & Scranton MI. (2006) Microbial ecology of the Cariaco Basin's oxic/anoxic interface: the U.S.-Venezuelan CARIACO times series program. In: Neretin LN (ed), Past and Present Water Column Anoxia, NATO Sci Ser., Springer, Netherlands, p. 473-499.

Scranton MI, Taylor GT, Astor Y & Muller-Karger F (2006) Temporal variability in the nutrient chemistry of the Cariaco Basin.In: Neretin LN (ed), Past and Present Water Column Anoxia, NATO Sci Ser., Springer, Netherlands, p. 139-160.

Hayes MK, Taylor GT, Astor Y, & Scranton MI (2006) Vertical distributions of thiosulfate and sulfite in the Cariaco Basin. Limnol. Oceanogr. 51: 280-287

LeBlanc LA, Gulnick JD, Brownawell BJ & Taylor GT(2005) The influence of sediment resuspension on degradation of phenanthrene in flow-through microcosms. Marine Environ. Res. 61: 202-223

Ho, T-Y, Taylor GT, Astor Y, Varela R, Muller-Karger F & Scranton MI (2004) Vertical and temporal variability of redox zonation in the water column of the Cariaco Basin: implications for organic oxidation pathways.  Mar. Chem. 86: 89-104.

Caron DA, Gobler CJ, Lonsdale DJ, Cerrato RM, Schaffner RA, Rose JM, Buck NJ, Taylor G, Boissonneault KR & Mehran R (2004) Microbial herbivory on the brown tide alga, Aureococcus anophagefferens: results from natural ecosystems, mesocosms and laboratory experiments. Harmful Algae, 3: 439-457.

Stoeck T, Taylor GT & Epstein S (2003)Novel eukaryotes from a permanently anoxic Cariaco Basin (Caribbean Sea). Appl. Environ. Microbiol. 69: 5656-5663.

Taylor GT, Hein C & Iabichella M (2003) Temporal variations in viral distributions in the anoxic Cariaco Basin.  Aquatic Microbial Ecology, 30: 103-116.

Taylor GT, Way J & Scranton MI (2003) Transport and planktonic cycling of organic carbon in the highly urbanized Hudson River estuary. Limnol. Oceanogr. 48: 1779-1795.

Taylor GT, Way J, Yu Y & Scranton MI (2003) Patterns of hydrolytic ectoenzyme activity among bacterioplankton communities in the lower Hudson River and Western Long Island Sound estuaries.  Mar. Ecol. Prog. Ser. 263:1-15.

Scranton MI, Taylor GT, Astor Y & Muller-Karger F (2003) Comparison of the controls on the structure of the oxic/anoxic interface in the Cariaco Basin and the Black Sea. In: Yilmaz A. (ed.) Oceanography of the Eastern Mediterranean and Black Sea, Tubitak Publ., Ankara, Turkey, p. 628-634.

Ho T-Y, Scranton MI, Taylor GT, Thunell RC, Varela R & Muller-Karger F (2002) Acetate cycling in the water column of the Cariaco Basin:  Seasonal and vertical variability and implication for carbon cycling.  Limnol. Oceanogr. 47: 1119-1128.

Anderson TH & Taylor GT(2001) Nutrient pulses, plankton blooms and hypoxia in western Long Island Sound. Estuaries, 24: 228-243.