C. Claret et al., Functional processes versus state variables: interstitial organic matter pathways in floodplain habitats, CAN J FISH, 58(8), 2001, pp. 1594-1602
Citations number
43
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
We assessed the potential rates of two microbial processes, cellulose decom
position potential (CDP) and hydrolytic activity, to explore the relationsh
ip of these functional measurements with several state variables of organic
matter. Samples were collected from two interstitial sites in the main cha
nnel of the Rhone River and 10 sites on the alluvial floodplain representin
g five habitat types defined by sediment size (fine versus coarse sediments
) and interstitial water origin (surface water versus groundwater). Althoug
h sites with fine sediments had more interstitial total organic matter, ref
ractory and biodegradable dissolved organic carbon concentrations did not d
iffer among habitat types. Unlike the floodplain, the main channel had high
CDP and low hydrolytic activity. In the floodplain, functional measurement
s varied consistently, and both CDP and hydrolytic activity were lowest at
the sites with coarse sediments. Our data imply that microbially mediated p
rocesses are different in the main channel and the floodplain and that low
levels of organic matter in the coarse sediments are probably due to slow r
ates of accrual rather than rapid rates of decomposition. Furthermore, the
lack of correlation between functional variables and dissolved organic carb
on concentrations illustrates the dangers of interpreting ecosystem process
es or ecological integrity based solely on state variables.