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Trophic position of zebra mussel veligers and their use of dissolved organic carbon
Author(s) -
Barnard Christine,
Martineau Christine,
Frenette Jean-Jacques,
Dodson Julian J.,
Vincent Warwick F.
Publication year - 2006
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2006.51.3.1473
Subject(s) - trophic level , food web , zebra mussel , dreissena , biology , zooplankton , dissolved organic carbon , ecology , detritivore , phytoplankton , seston , mussel , bivalvia , environmental chemistry , mollusca , chemistry , nutrient
We evaluated by stable isotope analysis the trophic structure of an estuarine transition zone (ETZ) food web and the role of an invasive species, the veliger stage of the zebra mussel Dreissena polymorpha . In the St. Lawrence ETZ, where zebra mussel veligers are now the dominant zooplankton in summer, δ 13 C ranged from −31.2‰ (seston) to −16.1‰ (adult fish) and δ 15 N ranged from 2.6‰ to 17.4‰. Isotopic analysis of samples indicated that the overall food web was largely supported by autochthonous phytoplankton rather than by allochthonous terrestrial carbon. Large differences among the isotopic signals of veligers, cladocerans, and copepods suggested the use of different proportions of food items, and the isotopic values of fish larvae indicated no significant assimilation of veligers. The δ 13 C signature of the veligers was in a range consistent with feeding on free‐living bacteria and dissolved organic carbon (DOC) or both, and freshwater algae incubated in situ. To investigate the possibility of DOC uptake by the veligers, we incubated veligers on 14 C‐labelled algal lysates. There was rapid uptake of DOC and incorporation into biomass, equivalent to 6% of the soft tissue dry weight per hour. Zebra mussel veligers are likely using autochthonous DOC as an alternate food source, and they occupy an exotic trophic position in which there is little direct interaction with other major components of the ETZ food web.