Degradation of copepod fecal pellets: key role of protozooplankton

Poulsen, Louise K.; Iversen, Morten Hvitfeldt

doi:10.3354/meps07611

Cited by 69 publications

(66 citation statements)

References 38 publications

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“…In this study, we demonstrated that large FP (length ഠ450 µm) are in fact subject to grazing by dinoflagellates, as previously reported for smaller FP (Poulsen & Iversen 2008) but not for large FP (Svensen et al 2012). However, the present experiment was carried out over 48 h, a time frame that might allow large and fast-sinking FP (50 to 300 m d −1 ) to escape the vertical zone where they would be exposed to grazing from dinoflagellates.…”

Section: In Situ Degradation Of Copepod Faecal Pelletsmentioning

confidence: 69%

“…An exponential function was chosen to describe FP degradation rates in this experiment, according to Poulsen & Iversen (2008). It should be noted that degradation rates can also be estimated in terms of daily carbon-specific degradation rates or daily loss rates and that these methods indicate lower degradation rates and no additive effect of copepods and dinoflagellates in our experiment.…”

Section: Discussionmentioning

confidence: 99%

“…In temperate areas, like the North Sea, plankton organisms < 200 µm were the main degraders of medium-sized copepod pellets (Poulsen & Kiørboe 2006), and dinoflagellates appear to play a key role (Poulsen & Iversen 2008). Conversely, in a study conducted in northern Norway, protozooplankton alone did not seem capable of degrading large copepod FP within relevant time-frames, although in concert with filter-feeding copepods, the degradation was significant (Svensen et al 2012).…”

Section: Introductionmentioning

confidence: 96%

“…For instance, protozooplankton are able to use FP as a direct food source (Jacobsen & Azam 1984, Noji 1991, Turner 2002, Poulsen & Kiørboe 2006, Poulsen & Iversen 2008. Bacteria originating from the copepod's gut and pelagic bacteria can also degrade FP (Turner 1979, Gowing & Silver 1983, Jacobsen & Azam 1984, Hansen & Bech 1996.…”

Section: Introductionmentioning

confidence: 99%

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Increased degradation of copepod faecal pellets by co-acting dinoflagellates and Centropages hamatus

Svensen

Morata

Reigstad

2014

Mar. Ecol. Prog. Ser.

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Copepod faecal pellets (FP) are carbon-rich particles possibly of great importance for the biological pump. However, most FP are degraded within the euphotic zone, by processes not yet fully understood. In a series of experiments conducted in Gullmarsfjorden, Sweden, we investigated degradation rates (r, d ) was higher than the sum of the degradation rates measured under each individual condition (bacteria + dinoflagellates + C. hamatus). We suggest an interactive effect of dinoflagellates and copepods acting together -that the copepods were mechanically breaking up large FP, making the FP more available for further degradation by the dinoflagellates. This finding may have implications for understanding FP fluxes and carbon export in the ocean and points to a more complex 'coprophagous filter' (sensu González & Smetacek 1994; Mar Ecol Prog Ser 113:233−246)

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Section: In Situ Degradation Of Copepod Faecal Pelletsmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Increased degradation of copepod faecal pellets by co-acting dinoflagellates and Centropages hamatus

Svensen

Morata

Reigstad

2014

Mar. Ecol. Prog. Ser.

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“…could play a major role in FP retention. In an experiment investigating the effect of various size-fractions of grazers, Poulsen & Iversen (2008) concluded that heterotrophic ciliates and dinoflagellates are the main degraders of small FP from the calanoid copepod Acartia tonsa and that the effect of copepods on degradation rates is comparatively minor. At high latitudes, the copepod community is dominated by larger copepod species producing larger FP.…”

mentioning

confidence: 99%

Degradation of copepod faecal pellets in the upper layer: role of microbial community and Calanus finmarchicus

Svensen¹,

Riser²,

Reigstad³

et al. 2012

Mar. Ecol. Prog. Ser.

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Copepod faecal pellets (FP) are considered important contributors to vertical carbon flux, but investigations comparing FP production with FP export using sediment traps conclude that vertical export is not their only fate. FP are degraded to a large extent in the upper 60 m, and even among large, fast-sinking FP, only a fraction reaches sediment traps deeper than 200 m. Retention mechanisms for copepod FP are still not well understood. In order to investigate the relative importance of the small (<180 µm) compartment of the plankton community versus larger filter-feeding copepods for degradation of large, fast-sinking FP, we incubated FP produced by Calanus finmarchicus (Gunnerus) in 180 µm-filtered water from the chlorophyll a maximum. From a series of experiments, we found that the degradation of large FP is time-dependent, as no degradation was apparent after 20 or 48 h of incubation, but after 72 h FP volume was reduced by 32%. We also found that large filter-feeding copepods may facilitate the degradation process, since FP degradation increased from 0 to 75% after 48 h of incubation in the presence of 5 C. finmarchicus. We conclude that ciliates and dinoflagellates are able to degrade large copepod FP, but that this process is too slow to explain observed retention of large FP in the upper 200 m of the water column due to fast sinking of large particles. Rather than looking for single-factor explanations for flux-regulating processes, we stress the importance of investigating combined effects in relevant time frames to understand the complexity of carbon flux regulation in natural systems. KEY WORDS: Faecal pellet · Faecal pellet retention · Microbial degradation · Faecal pellet fragmentation · Calanus finmarchicus · Carbon cycling Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 462: [39][40][41][42][43][44][45][46][47][48][49] 2012 by copepods. Gon zález & Smetacek (1994) hypothesised that the abundant cyclopoid copepods Oithona spp. play a key role in the retention of copepod FP, but evidence is conflicting, indicating that Oithona spp. may be indi cators for a retention community rather than the retaining organisms (Reigstad et al. 2005, Poulsen & Kiør boe 2006. This shows that organisms other than Oithona spp. could play a major role in FP retention. In an experiment investigating the effect of various size-fractions of grazers, Poulsen & Iversen (2008) concluded that heterotrophic ciliates and dinoflagellates are the main degraders of small FP from the calanoid copepod Acartia tonsa and that the effect of copepods on degradation rates is comparatively minor. At high latitudes, the copepod community is dominated by larger copepod species producing larger FP. It is therefore relevant to ask if the same groups of organisms and mechanisms are important for degradation of larger FP at high latitudes.Sediment trap investigations revealed considerable attenuation of particulate organic carbon (POC) over a limited depth range (30−60 m) in areas whe...

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Using Lagrangian‐based process studies to test satellite algorithms of vertical carbon flux in the eastern North Pacific Ocean

et al. 2015

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The biological carbon pump is responsible for the transport of ∼5–20 Pg C yr−1 from the surface into the deep ocean but its variability is poorly understood due to an incomplete mechanistic understanding of the complex underlying planktonic processes. In fact, algorithms designed to estimate carbon export from satellite products incorporate fundamentally different assumptions about the relationships between plankton biomass, productivity, and export efficiency. To test the alternate formulations of export efficiency in remote‐sensing algorithms formulated by Dunne et al. (2005), Laws et al. (2011), Henson et al. (2011), and Siegel et al. (2014), we have compiled in situ measurements (temperature, chlorophyll, primary production, phytoplankton biomass and size structure, grazing rates, net chlorophyll change, and carbon export) made during Lagrangian process studies on seven cruises in the California Current Ecosystem and Costa Rica Dome. A food‐web based approach formulated by Siegel et al. (2014) performs as well or better than other empirical formulations, while simultaneously providing reasonable estimates of protozoan and mesozooplankton grazing rates. By tuning the Siegel et al. (2014) algorithm to match in situ grazing rates more accurately, we also obtain better in situ carbon export measurements. Adequate representations of food‐web relationships and grazing dynamics are therefore crucial to improving the accuracy of export predictions made from satellite–derived products. Nevertheless, considerable unexplained variance in export remains and must be explored before we can reliably use remote sensing products to assess the impact of climate change on biologically mediated carbon sequestration.

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Degradation of copepod fecal pellets: key role of protozooplankton

Cited by 69 publications

References 38 publications

Increased degradation of copepod faecal pellets by co-acting dinoflagellates and Centropages hamatus

Increased degradation of copepod faecal pellets by co-acting dinoflagellates and Centropages hamatus

Degradation of copepod faecal pellets in the upper layer: role of microbial community and Calanus finmarchicus

Using Lagrangian‐based process studies to test satellite algorithms of vertical carbon flux in the eastern North Pacific Ocean

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