Trophic role of small cyclopoid copepod nauplii in the microbial food web: a case study in the coastal upwelling system off central Chile |
| |
Authors: | Daniela Böttjer Carmen E Morales Ulrich Bathmann |
| |
Institution: | 1. FB2 Biology/Chemistry, University of Bremen, Leobenerstr. NW2A, 28359, Bremen, Germany 2. Departamento de Oceanografía, Estación de Biología Marina, Centro FONDAP-COPAS (Center for Oceanographic Research in the Eastern South Pacific), Universidad de Concepción, Casilla 44, Dichato, VIII Región, Chile 4. Department of Oceanography, University of Hawaii, 1000 Pope Road, Marine Science Building 620, Honolulu, Hi, 96822, USA 3. Alfred-Wegener-Institut for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany
|
| |
Abstract: | Copepod grazing impact on planktonic communities has commonly been underestimated due to the lack of information on naupliar
feeding behaviour and ingestion rates. That is particularly true for small cyclopoid copepods, whose nauplii are mainly in
the microzooplankton size range (<200 μm). The trophic role of Oithona spp. nauplii was investigated off Concepción (central Chile, ~36°S) during the highly productive upwelling season, when maximum
abundances of these nauplii were expected. Diet composition, ingestion rates, and food-type preferences were assessed through
grazing experiments with different size fractions of natural planktonic assemblages (<3, <20, <100, and <125 μm) and cultures
of the nanoflagellate Isochrysis galbana. When the Oithona spp. nauplii were offered a wide range of size fractions as food (pico- to microplankton), they mostly ingested small (2–5 μm)
nanoflagellates (5–63 × 103 cells nauplius−1 day−1). No ingestion on microplankton was detected, and picoplankton was mainly ingested when it was the only food available. Daily
carbon (C) uptake by the nauplii ranged between 28 and 775 ng C nauplius−1, representing an overall mean of 378% of their body C. Our relatively high ingestion rate estimates can be explained by methodological
constraints in previous studies on naupliar feeding, including those dealing with “over-crowding” and “edge” effects. Overall,
the grazing impact of the Oithona spp. nauplii on the prey C standing stocks amounts up to 21% (average = 13%) for picoplankton and 54% (average = 28%) for
nanoplankton. These estimates imply that the nauplii of the most dominant cyclopoid copepods exert a significant control on
the abundances of nanoplankton assemblages and, thereby, represent an important trophic link between the classical and microbial
food webs in this coastal upwelling system. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|