Quantitative contribution of DOC release by the macrophyte-epiphyte complex in different ecosystems

The loading of terrestrial dissolved organic carbon (DOC) can contribute significantly to the energy pathways of lake ecosystems (TRANVIK 1992, PACE et al. 2004, CARPENTER et al. 2005, KRITZBERG et al. 2006). Water column metabolism could also be sustained by benthic production, however, because i t often dominates the overall productivity o f the system, particularly in shallow lakes (VADEBONCOEUR et al. 2003). Living macrophytes are known to release DOC (WETZEL & MANNY 1972, GoDMAIRE & NALEWAJKO 1989, BARRÓN et al. 2003) and area potential source of carbon for water column metabolism; therefore, we determined the relative contribution oftotal quantity ofDOC released by living macrophytes to the entire DOC pool to estimate its potential contribution to metabolism at the ecosystem scale. We measured in situ DOC release rates by the macrophyte-epiphyte complex (Demarty and Prairie, unpubl) and compared them to DOC loads from the watersheds.