HR: 1330h
AN: NB33I-01    [Abstracts]
TI: The Source of Bacteria Involved in the Break-Down of Gammarus Pulex Faecal Pellets Using Image Analysis
AU: * Joyce, P
EM: p.joyce@ucl.ac.uk
AF: Department of Biology, University College, London, Gower Street , London, WC1E 6BT United Kingdom
AU: Wotton, R
EM: r.wotton@ucl.ac.uk
AF: Department of Biology, University College, London, Gower Street , London, WC1E 6BT United Kingdom
AB: Bacteria survive passage through the gut of aquatic animals and are implicated in the break-down of POM (such as faecal pellets) in aquatic systems. There is evidence that bacteria that survive gut passage are the cause of the initial break-down of faecal pellets, rather than colonisation by bacteria from the environment. Gammarus is the dominant shredder in lowland permeable catchments ("chalk streams") in England and feeds on allochthonous detritus such as fallen leaves. Gammarus faecal pellets could form important pathways for transfer of organic matter in chalk streams. We incubated Gammarus faecal pellets for 80 days in stream water using combinations of treatments (autoclaving the stream water or pellets; fresh non-autoclaved stream water or pellets; reducing bacterial activity using Gentamicin; combinations of these treatments) to assess the role of surviving and colonising bacteria on the break-down process. Break-down was measured using image analysis. Results show that treatments with fresh pellets show much higher levels of break-down than fully autoclaved controls, treatments with fresh stream water but autoclaved pellets, or treatments with Gentamicin. Bacteria surviving gut passage therefore seem to play a greater role in faecal pellet break-down than those colonising from the environment.
DE: 1848 Networks
DE: 1899 General or miscellaneous
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly