Atienza, D., A. Calbet, E. Saiz, M. Alcaraz & I. Trepat. (2006). Trophic impact, metabolism, and biogeochemical role of the marine cladoceran Penilia avirostris and the co-dominant copepod Oithona nana in NW Mediterranean coastal waters. Marine Biology. 150(2):221-235.
Atienza, D., A. Calbet, E. Saiz, M. Alcaraz & I. Trepat
2006
Trophic impact, metabolism, and biogeochemical role of the marine cladoceran Penilia avirostris and the co-dominant copepod Oithona nana in NW Mediterranean coastal waters.
Marine Biology
150(2):221-235.
Publication
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In this work we studied the trophic ecology and feeding impact of the cladoceran Penilia avirostris and the cyclopoid copepod Oithona nana, the two dominant zooplankters in the summer communities of the coastal NW Mediterranean, on the naturally occurring microbial communities. In order to ascertain carbon surplus for growth and reproduction and the contribution to carbon and nitrogen recycling of these two species, we also determined their basal metabolism and excretion rates. The experiments conducted during summers 2002, 2003, and 2004 indicate that P. avirostris grazed mostly upon small Xagellates, dinoXagellates, and diatoms, whereas O. nana had a narrower prey range, selecting motile organisms such as ciliates and occasionally dinoXagellates. The grazing impact of both species accounted, on average, for <10% of the standing stock of the microbial groups considered. In spite of the oligotrophic conditions, the feeding activity of P. avirostris is in general suYcient to compensate basal metabolism and allows a surplus for growth and reproduction. This was not the case for O. nana, its daily rations being often lower than the carbon basal demands. Regarding excretion rates, both species presented diVerent N:P excretion ratios, the ones of O. nana falling within values typical for copepods, whereas the absence of detectable phosphorus excretion by P. avirostris implied an unbalance recycling with respect to typical RedWeld ratio composition of marine seston.
