Research Highlights - Trophic Ecology

How food webs are controlled from below
Our observations on shallow lakes and ponds in northern Finland, subarctic Québec, arctic Canada and northern Alaska show that they often contain high densities of zooplankton (often several co-existing species) despite low concentrations of nutrients and phytoplankton in the water. In our research on this puzzling anomaly we have found that several of the zooplankton species are able to feed on the nutrient-rich microbial mat communities that form a layer on the bottom of these waterbodies. Some species swim down to feed directly on the mats, while others use fragments of benthic mat that are brought up into suspension by the wind.

Further details in: Rautio M, Vincent WF 2006. Benthic and pelagic food resources for zooplankton in shallow high-latitude lakes and ponds. Freshwater Biology 51: 1038-1052.

New food sources for aquatic food webs
Our research in the St Lawrence River has shown that the larval stage of zebra mussels are now the dominant zooplankton during summer. In our studies of trophic relationships we have found that in general the zooplankton in this river, and especially the estuarine transition zone, selectively use only a small fraction of the total available particulate food available to them. The zebra mussel larvae, however, are capable of feeding directly on the large pool of dissolved organic carbon (DOC). This intriguing discovery suggests that DOC could participate directly as a carbon source in some aquatic food webs.

Further details in: Barnard, C., Martineau, C., Frenette, J-J, Dodson, J. & Vincent W.F. 2005. Trophic position of zebra mussel veligers and their use of dissolved organic carbon. Limnology and Oceanography 51: 1473-1484.