Importance of copepods versus appendicularians in vertical carbon fluxes in a Swedish fjord

Abstract

We examined and quantified the contributions of copepods and appendicularians to the vertical flux of carbon during autumn and spring in Gullmar Fjord (west coast of Sweden). Faecal pellet-production rate was determined for major copepod and appendicularian species. In addition, house-production rates were estimated for the appendicularian Oikopleura dioica. Vertical flux of pigments, faecal carbon and appendicularian houses were measured using short-term (24 h) deployments of sediment traps at 2 depths (15 and 30 m). Copepods dominated the community biomass in both spring and autumn and their pellets dominated the faecal carbon flux. O. dioica houses with attached detritus were an important component of the biogenic carbon flux in October (15.3 mg C m -2 d -1), equalling the contribution from copepods at 15 m and 50% of the flux at 30 m. At that time, we observed a loss rate of 70% d -1 of the houses produced in the water column. In the spring, although Fritillaria borealis dominated the appendicularians, its houses did not appear to contribute to the biogenic flux. Our results suggest that oikopleurids and fritillariids may not operate equivalently in biogeochemical cycles. Because of the significant contribution of appendicularians to carbon fluxes, they should be incorporated in future flow models of coastal oceans KEY WORDS: Carbon flux · Appendicularians · Copepods · Faecal pellet production · Marine snow Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 241: [125][126][127][128][129][130][131][132][133][134][135][136][137][138] 2002 extruded in short time intervals as faecal pellets (López-Urrutia & Acuña 1999). Some of these faecal pellets, together with uneaten particles, eventually clog the house, which is then abandoned and replaced by a new house, approximately 4 to 6 times per day (Deibel 1988, Alldredge 1992, Hansen et al. 1996, Sato et al. 2001. Thus, appendicularian houses together with their faecal pellets may constitute an important component of marine snow (Alldredge & Gotschalk 1990, Hansen et al. 1996. Furthermore, due to the high efficiency with which appendicularians ingest nanoplankton and picoplankton (King et al. 1980, Deibel 1988, Deibel & Lee 1992, Acuña et al. 1996, they constitute a pathway through which small cells that otherwise do not sink may be transported out of the euphotic zone. Consequently, when appendicularians are abundant, small phytoplankton cells may contribute much more to the vertical flux than when the community is dominated by copepods (Urban et al. 1992, Hansen et al. 1996.Oikopleura and Fritillaria species are abundant pelagic tunicates in coastal waters (e.g. Acuña et al. 1995, Gorsky et al. 2000. On the western Norwegian coast, O. dioica is one of the most widely distributed species (Gorsky et al. 2000). In the Kattegat, appendicularians also represent an important component of the zooplankton community during the autumn and spring blooms (Nielsen & Hansen 1999). The abundance of copepods in these bo...

Fatty acid transformation in zooplankton: from seston to benthos

“…The POC flux varied only by a factor of 2 and was lower than previous estimates from the Gullmar Fjord (Waite et al 2005). Highest pigment flux at both depths was similar to estimates from the spring bloom in the fjord (Vargas et al 2002), but the phytoplankton were far from bloom conditions in the fjord (Waite et al 2005). Estimated sinking velocities were always higher at 30 m than at 15 m, which is consistent with a gradual increase in particle or aggregate size with depth (e.g.…”

“…Sedimenting pellets, pigments, POC and lipids were estimated from duplicate sediment traps at 15 and 30 m depth following Vargas et al (2002). Traps were 60 cm long and 8 cm diameter cylinders moored at the sampling station (43 m depth).…”

Plankton community structure and carbon cycling in a coastal upwelling system. II. Microheterotrophic pathway

“…Small calanoid and cyclopoid copepods and appendicularians are known to be largely omnivorous and bacterivorous respectively (e.g. Tiselius 1989, Dagg et al 1996, Vargas et al 2002, Zeldis et al 2002, Vargas & González 2003. Therefore, when small zooplankton species feed on protozoans (which in turn feed efficiently on pico-and nanoplankton), the energy transfer from the microbial loop (including bacteria and protists), and also from the microbial food web (including autotrophic pico-and nanoplankton) to higher trophic levels may be greater than previously assumed.…”

Tracking Fatty Acids From Phytoplankton to Jellyfish Polyps Under Different Stress Regimes: A Three Trophic Levels Experiment

“…Jellyfish are drawing increasingly attentions because of a preceived incidence of mass developments and of their potential capacity of driving food webs structure (West et al, 2009) and their importance in global biogeochemical cycles (Vargas et al, 2002;Lebrato et al, 2013). Yet little empirical studies can be found in the literature on the dynamic of essential or semiessential biomolecules (e.g., FAs) in gelatinous zooplankton and their transfer along food chains dominated by jellyfish.…”