Connections between bacteria and organic matter in aquatic ecosystems: Linking microscale ecology to global carbon cycling

Dana E. Hunt, Eva Ortega-Retuerta, Craig E. Nelson

Full Citation: Dana E. Hunt, Eva Ortega-Retuerta, Craig E. Nelson. 2010. Connections between bacteria and organic matter in aquatic ecosystems: Linking microscale ecology to global carbon cycling, p. 110-128. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.110]

ABSTRACT: The primary aim of this chapter is to synthesize research relevant to the microscale interactions between bacteria and organic matter in freshwater and marine pelagic environments. Heterotrophic bacterioplankton provide an important ecosystem service by remineralizing dissolved and particulate organic material in aquatic ecosystems. However, both heterotrophs and organic matter are generally treated as "black boxes" in models of pelagic ecosystem metabolism owing to our poor understanding of their diversity and spatial/ temporal dynamics. Such models necessarily mask a complex set of interactions because of the difficulty in observing and quantifying this "microscale" ecology. Bacteria exhibit tremendous phylogenetic and metabolic diversity, and we now understand that organic matter comprises a heterogeneous matrix of particles, gels, polymeric matrices, colloids, and dissolved macromolecules. The physicochemical organic matter continuum is dynamic and patchy; which translates to a complex array of ecological microenvironments for bacterioplankton. The phylogenetic and functional diversity of bacteria is thus intertwined with the chemical and physical complexity of their organic matter resources. Characterizing bacterial-organic matter interactions at the appropriate temporal and spatial scales will fundamentally enhance our knowledge of pelagic ecosystems.