IR Home
AME
Home
Editors
Forthcoming
Information
Subscribe
Journals
Home
MEPS
AME
CR
DAO
ESEP
ESR
Search
Subscribe
Book Series
EE Books
Top Books
ESEP Books
Order
EEIU Brochures
(pdf format)
Discussion Forums
Home
Institutions
International Ecology Institute
Eco-Ethics International Union
Foundation
Otto Kinne Foundation
| |
AME 34:151-164 (2004)
|
Abstract
|
Plankton community structure and carbon cycling in a coastal upwelling system. I. Bacteria, microprotozoans and phytoplankton in the diet of copepods and appendicularians
Cristian A. Vargas1,*, Humberto E. González2
1Department of Oceanography, Universidad de Concepcion, Casilla 160-C, Concepcion, Chile
2Institute of Marine Biology 'Dr. Jürgen Winter', Universidad Austral de Chile, Casilla 567, Valdivia, Chile
*Email: crvargas@udec.cl
ABSTRACT: Copepod and appendicularian grazing experiments using naturally occurring planktonic assemblages from a coastal embayment (Mejillones Bay, northern Chile upwelling system at 23ª S) were conducted between October 2000 and October 2001. Total
carbon ingestion rates based on size-fractioned chlorophyll data showed that dominant copepods (Acartia tonsa, Centropages brachiatus, Oithona similis and Paracalanus parvus) ingested between 2 and 8 µgC ind.-1
d-1, while appendicularians (Oikopleura dioica and O. longicauda) ingested ~3 to 4 µgC ind.-1 d-1. Even when most copepods were feeding on larger cells (>23 µm) at high rates, the smaller copepods also
grazed at similar rates on nanoplankton (5 to 23 µm) and picoplankton (<5 µm). In contrast, chain-forming diatoms were cleared at very low rates by copepods. Bacteria were cleared only by appendicularians (~170 to ~400 ml ind.-1
d-1) but not by any copepod, while heterotrophic protists constituted a substantial proportion in the diet of both copepods and appendicularians (~10 to 100% body carbon d-1), particularly during austral spring. Occasionally, copepod
C-specific ingestion on heterotrophs was similar to that on autotrophic cells. Large ciliates and dinoflagellates were cleared but not ingested by the appendicularian O. dioica, suggesting a mechanism of trapping large cells in their houses and
implying a rapid export of fresh material. Since heterotrophs are a common component in the diet of these 2 groups (omnivory by copepods and bacterophagy by appendicularians), they can potentially affect microbial food webs in this upwelling system and
thus carbon export.
KEY WORDS: Carbon flux · Omnivory · Microzooplankton · Clearance rate · Copepods · Appendicularians
Full text in pdf format
Published in AME Vol.
34, No. 2
(2004) on February 4
Print ISSN: 0948-3055; Online ISSN: 1616-1564.
Copyright © Inter-Research, Oldendorf/Luhe, 2004
|