Linking foraging strategies of marine calanoid copepods to patterns of nitrogen stable isotope signatures in a mesocosm study

Sommer, Frank; Saage, Andrea; Santer, Barbara; Hansen, Thomas; Sommer, Ulrich

doi:10.3354/meps286099

Cited by 27 publications

(26 citation statements)

References 28 publications

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“…While we cannot rule out other explanations at present, the pattern observed looked like a strong imprint of zooplankton grazing at higher temperatures. It has been shown in summer experiments that copepod grazing primarily reduces large phytoplankton, while small phytoplankton is at times even favoured, because they are released from ciliate grazing pressure (Feuchtmayr 2004;Grané li and Turner 2002;Sommer et al 2003aSommer et al , b, 2005a. Contrary to summer conditions, when ciliates preferentially feed on small phytoplankton (Sommer et al 2005b), the ciliates in our experiment had also fed on large algae (Aberle et al 2006), which is quite typical for the start of the seasonal growth cycle (Montagnes et al 1988).…”

Section: Succession Patternsmentioning

confidence: 56%

An indoor mesocosm system to study the effect of climate change on the late winter and spring succession of Baltic Sea phyto- and zooplankton

et al. 2006

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An indoor mesocosm system was set up to study the response of phytoplankton and zooplankton spring succession to winter and spring warming of sea surface temperatures. The experimental temperature regimes consisted of the decadal average of the Kiel Bight, Baltic Sea, and three elevated regimes with 2°C, 4°C, and 6°C temperature difference from that at baseline. While the peak of the phytoplankton spring bloom was accelerated only weakly by increasing temperatures (1.4 days per degree Celsius), the subsequent biomass minimum of phytoplankton was accelerated more strongly (4.25 days per degree Celsius). Phytoplankton size structure showed a pronounced response to warming, with large phytoplankton being more dominant in the cooler mesocosms. The first seasonal ciliate peak was accelerated by 2.1 days per degree Celsius and the second one by 2.0 days per degree Celsius. The overwintering copepod populations declined faster in the warmer mesocosm, and the appearance of nauplii was strongly accelerated by temperature (9.2 days per degree Celsius). The strong difference between the acceleration of the phytoplankton peak and the acceleration of the nauplii could be one of the ''Achilles heels'' of pelagic systems subject to climate change, because nauplii are the most starvation-sensitive life cycle stage of copepods and the most important food item of first-feeding fish larvae.

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Section: Succession Patternsmentioning

confidence: 56%

An indoor mesocosm system to study the effect of climate change on the late winter and spring succession of Baltic Sea phyto- and zooplankton

et al. 2006

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“…For example, to overcome nonlinear feeding responses due to food saturating conditions, a modified protocol can be used (Paterson et al 2008; this study). To prevent nutrient limiting conditions in the experimental vessels, often dialysis bags are incubated in situ (Landry 1993;Sommer et al 2005a, b;Aberle et al 2007) or nutrients are added in excess to the dilution series (Landry 1993;Fonda Umani et al 2005;First et al 2009) in bottle incubations. As we wanted to keep conditions in microzooplankton und copepod grazing experiments comparable, we chose the second alternative (bottle incubations), that was also necessary for correction of trophic cascade effects in the copepod grazing set-up (Nejstgaard et al 1997(Nejstgaard et al , 2001Fonda Umani et al 2005).…”

Section: Discussionmentioning

confidence: 99%

“…The release of microzooplankton grazing pressure can promote nanoflagellates, an important prey of ciliates, and thus affect bacterial abundance negatively as bacteria are the main food source of nanoflagellates (Zöllner et al 2009). Even more pronounced effects were reported for chlorophyll a concentrations: copepod grazers reduced microzooplankton biomass and led to overall higher chlorophyll a concentrations due to the release of small sized flagellates from microzooplankton grazing (Sommer et al 2003(Sommer et al , 2005a.…”

Section: Microzooplankton and T Longicornis Grazing Impact On The Phmentioning

confidence: 98%

The role of ciliates, heterotrophic dinoflagellates and copepods in structuring spring plankton communities at Helgoland Roads, North Sea

et al. 2011

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Mesocosm experiments coupled with dilution grazing experiments were carried out during the phytoplankton spring bloom 2009. The interactions between phytoplankton, microzooplankton and copepods were investigated using natural plankton communities obtained from Helgoland Roads (54°11.3 0 N; 7°54.0 0 E), North Sea. In the absence of mesozooplankton grazers, the microzooplankton rapidly responded to different prey availabilities; this was most pronounced for ciliates such as strombidiids and strobilids. The occurrence of ciliates was strongly dependent on specific prey and abrupt losses in their relative importance with the disappearance of their prey were observed. Thecate and athecate dinoflagellates had a broader food spectrum and slower reaction times compared with ciliates. In general, high microzooplankton potential grazing impacts with an average consumption of 120% of the phytoplankton production (P p ) were measured. Thus, the decline in phytoplankton biomass could be mainly attributed to an intense grazing by microzooplankton. Copepods were less important phytoplankton grazers consuming on average only 47% of P p . Microzooplankton in turn contributed a substantial part to the copepods' diets especially with decreasing quality of phytoplankton food due to nutrient limitation over the course of the bloom. Copepod grazing rates exceeded microzooplankton growth, suggesting their strong top-down control potential on microzooplankton in the field.Selective grazing by microzooplankton was an important factor for stabilising a bloom of less-preferred diatom species in our mesocosms with specific species (Thalassiosira spp., Rhizosolenia spp. and Chaetoceros spp.) dominating the bloom. This study demonstrates the importance of microzooplankton grazers for structuring and controlling phytoplankton spring blooms in temperate waters and the important role of copepods as top-down regulators of microzooplankton.

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“…), autotrophic picoplankton, dinoflagellates (e.g., Gymnodinium sp., Prorocentrum sp. ), and nanoflagellates (Sommer et al, 2005).…”

Section: Study Areamentioning

confidence: 99%

“…We mimicked the natural nutrient input by manually adding nutrient to the enclosed mesocosms, using nitrogen concentrations that compensated for the loss of N caused by sedimentation and Redfield ratios for phosphorus and silicon additions as described in previous studies (Sommer et al, 2005;Olsen et al, 2006). Such nutrients additions maintained the low natural phytoplankton concentrations yet avoided accumulation of unrealistically high concentrations of phytoplankton biomass (Børsheim et al, 2005).…”

Section: Mesocosmsmentioning

confidence: 99%

Copepods Boost the Production but Reduce the Carbon Export Efficiency by Diatoms

et al. 2018

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The fraction of net primary production that is exported from the euphotic zone as sinking particulate organic carbon (POC) varies notably through time and from region to region. Phytoplankton containing biominerals, such as silicified diatoms have long been associated with high export fluxes. However, recent reviews point out that the magnitude of export is not controlled by diatoms alone, but determined by the whole plankton community structure. The combined effect of phytoplankton community composition and zooplankton abundance on export flux dynamics, were explored using a set of 12 large outdoor mesocosms. All mesocosms received a daily addition of minor amounts of nitrate and phosphate, while only 6 mesocosms received silicic acid (dSi). This resulted in a dominance of diatoms and dinoflagellate in the +Si mesocosms and a dominance of dinoflagellate in the −Si mesocosms. Simultaneously, half of the mesocosms had decreased mesozooplankton populations whereas the other half were supplemented with additional zooplankton. In all mesocosms, POC fluxes were positively correlated to Si/C ratios measured in the surface community and additions of dSi globally increased the export fluxes in all treatments highlighting the role of diatoms in C export. The presence of additional copepods resulted in higher standing stocks of POC, most probably through trophic cascades. However it only resulted in higher export fluxes for the −Si mesocosms. In the +Si with copepod addition (+Si +Cops) export was dominated by large diatoms with higher Si/C ratios in sinking material than in standing stocks. During non-bloom situations, the grazing activity of copepods decrease the export efficiency in diatom dominated systems by changing the structure of the phytoplankton community and/or preventing their aggregation. However, in flagellate-dominated system, the copepods increased phytoplankton growth, aggregation and fecal pellet production, with overall higher net export not always visible in term of export efficiency.

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Linking foraging strategies of marine calanoid copepods to patterns of nitrogen stable isotope signatures in a mesocosm study

Cited by 27 publications

References 28 publications

An indoor mesocosm system to study the effect of climate change on the late winter and spring succession of Baltic Sea phyto- and zooplankton

An indoor mesocosm system to study the effect of climate change on the late winter and spring succession of Baltic Sea phyto- and zooplankton

The role of ciliates, heterotrophic dinoflagellates and copepods in structuring spring plankton communities at Helgoland Roads, North Sea

Copepods Boost the Production but Reduce the Carbon Export Efficiency by Diatoms

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