Microbial food web

Feeding experiments coupled with 13C-leucine additions indicated that the zooplankton Cyclops derived some nutrition directly from the microbial food web. In addition, there was indirect evidence of DOM uptake by phytoplankton, and the subsequent transfer of that carbon to macrozooplankton. 

Fuhrman, J. 1992. Bacterioplankton roles in cycling of organic matter The microbial food web. In Primary Productivity and Biogeochemical Cycles in the Sea (P. G. Falkowski and A. D. Woodhead, Eds.), pp. 361-383. Plenum, New York. 

Auclair, J. C. 1995. Implications of increased UV-B induced photoreduction Iron(II) enrichment stimulated picocyanobacterial growth and the microbial food web in clear-water acidic Canadian Shield lakes. Canadian Journal of Fisheries and Aquatic Sciences 52 1782—1788. Auclair, J. C., P. Brassard, and P. Couture. 1985. Total dissolved phosphorus Effects of two molecular weight fractions on phosphorus cycling in natural phytoplankton communities. Water Research 19 1447—1453. 

Jansson, M., A. K. Bergstrom, P. Blomqvist, A. Isaksson, and A. Jonsson. 1999. Impact of allochthonous organic carbon on microbial food web carbon dynamics and structure in Lake Ortrasket. Archive fur Hydrobiologia 144 409—428. 

FIGURE I Photodegradation of DOM in surface waters of aquatic environments provides organic matter to the microbial food web. 

The second pattern evident in Table II is that the photochemically mediated transfer of carbon into the microbial food web is more pronounced for deep-water marine DOM than for surface water marine DOM. In two studies that explicitly compared relative photoreactivity of surface and deep samples, the biological lability of deep-water DOM was consistently greater after exposure to sunlight, whereas surface waters typically... 

Physiological Models in the Context of Microbial Food Webs... 

Jumars, P., J. Deming, P. Hill, L. Karp-Boss, P. L. Yager, and W. Dade. 1993. Physical constraints on marine osmotrophy in an optimal foraging context. Marine Microbial Food Webs 7 121-161. 

Williams, P. J. L. 1990. The importance of losses during microbial growth Commentary on the physiology, measurement, and ecology of the release of dissolved organic material. Marine Microbial Food Webs 4 175-206. 

The short-term, in situ bioavailability of organic matter is a complex function of intrinsic factors, such as the chemical characteristics of the DOM itself, which include of molecular weight distribution, the nutrient contents, and the relative contribution of broad classes of compounds and are determined by the source and the diagenetic state of the matter (Amon et al., 2001). The utilization of DOM and its apparent lability are also affected by extrinsic factors regulating the metabolism of bacteria and, therefore, the utilization of the organic matter by the bacterial community. These factors include temperature, the availability of inorganic and trace nutrients, trophic interactions within microbial food webs, and even the... 

Peduzzi, P., and G. J. Herndl. 1991. Decomposition and significance of seagrass leaf litter (Cymodocea modosa) for the microbial food web in coastal waters (Gulf of Trieste, Northern Adriatic Sea). Marine Ecology Progress Series 71 163—174. 

The microbial loop concept has been the prevailing paradigm for marine microbial food webs for two decades and has stimulated work on DOM sources and composition, rates of biomass production, transfer efficiencies, and respiratory losses (Benner, 1998 del Giorgio and Cole, 2000 Ducklow, 2000 Williams, 2000). The only major modification has arisen from new information on the abundance and ecology of viruses (Wilhelm and Suttle, 1999 Fuhrman, 1999, 2000). 

Pomeroy, L. R., and W. J. Wiebe. 1988. Energetics of microbial food webs. Hydrobiologia 159 7-18. 

At the ecosystem scale, the significance of microbial community organization is that it determines the magnitude and efficiency of carbon transfer to other portions of the food web. High density communities like biofilms and floes can be directly grazed by metazoans, which divert microbial and detrital carbon out of the microbial loop (Wotton, 1994). In dilute planktonic systems, much of the carbon reaches metazoans through a microbial food-web after two to three trophic transfers, only a small fraction of microbial production remains. 

Twiss, M.R., Campbell, P.G.C. and Auclair, J.-C. (1996) Regeneration, recycling, and trophic transfer of trace metals by microbial food-web organisms in the pelagic surface waters of Lake Erie, Limnology and Oceanography 41, 1425-1437. 

Blackburn, N., Azam, F, and Hagstrom, A., Spatially explicit simulations of a microbial food web, Limnol. Oceanogr., 42, 613, 1997. 

---