Pelagic ecology: definition of pathways for material and energy flux
Longhurst, A.R. (1989). Pelagic ecology: definition of pathways for material and energy flux, in: Denis, M. (Ed.) Océanologie: actualité et prospective. pp. 263-288 In: Denis, M. (Ed.) (1989). Océanologie: Actualité et prospective. Centre d' Océanologie: Marseille. ISBN 2-907752-00-6. 387 pp., more |
| Abstract | Perhaps the first priority task for marine ecologists in the coming decades is to quantify the global oceanic carbon cycle, a task already begun by geochemists. But models of carbon flux designed by ecologists are usually anthropocentric, treating shunts to ahiotic sinks as irrelevant, with emphasis being placed on flux leading to top predators. This is not the correct approach when quantifying global carbon flux, since very small proportions of total carbon flowing through ecosystems passes above the primary herbivore level, the majority passing directly from protozoa and algae to the interior of the ocean. The simple models used by geochemists to quantify this flux ignore major uncertainties concerning ecological processes, as do the classic particle size distribution models of ecologists. A generalised prey/predator ratio is often assumed to have been quantified, but this can easily be shown to be false: protists and metazoa have quite different prey/predator size relationships. The effects of viscosity are quite different for small and large biota, and there may be discontinuities across the range of Reynolds numbers encountered in the pelagos that will affect the distribution of biomass between size classes of biota. The dispersion of the autotrophic function among protists is far wider than usualy assumed and it remains quite impracticahle to trace pathways for energy flux within the protist microcosm, though this is where most carbon flux to oceanic reservoirs occurs. Models to simulate carbon flux in the ocean, required to quantify global carbon flux, are largely inadequate as presently formulated. What is urgently needed is better quantification of the roles of different trophic groups of protists in the pelagic ecosystem. |
|
