Mixotrophic nanoflagellates in coastal sediments in the western Baltic Sea

Moorthi, Stefanie; Berninger, Ulrike-Gabriele

doi:10.3354/ame045079

Cited by 7 publications

(6 citation statements)

References 39 publications

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“…Large amounts of flagellate FAs in suspension feeder profiles, particularly 22:6(n-3) and 16:4(n-3), confirmed the influence of SPOM in their diet, as shown in other seagrass meadows (Kharlamenko et al, 2001;Jaschinski et al, 2008). Abundances of flagellates can be high in the water column (Fenchel, 1988;Galois et al, 1996) and are generally very low in sediment (Moorthi and Berninger, 2006;Pascal et al, 2009), suggesting that flagellates come from phytoplankton. In our SPOM samples, low percentages of flagellate FAs were observed, that may be linked to either the scarcity of flagellate cells compared with those of diatoms or bacteria, or to sampling carried out between the short successions of flagellate blooms observed in Marennes-Oléron Bay (Héral et al, 1987).…”

Section: Influence Of Phytoplanktonic Materialssupporting

confidence: 61%

Trophic importance of diatoms in an intertidal Zostera noltii seagrass bed: Evidence from stable isotope and fatty acid analyses

Lebreton

Richard

Galois

et al. 2011

Estuarine, Coastal and Shelf Science

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A current predominant paradigm emphasizes the role of epiphytic algae for invertebrates in most seagrass food webs. However, in some intertidal Zostera noltii beds, epiphyte biomass is very low compared to microphytobenthos and seagrass biomasses. We assessed the role of microphytobenthos in a temperate intertidal Z. noltii bed by combining stable isotope and fatty acid (FA) analyses on primary producers, composite sources-suspended particulate organic matter (SPOM) and sediment surface organic matter (SSOM)-and the main macrofaunal consumers. Z. noltii showed high δ 13 C (−9.9‰) and high 18:2(n-6) and 18:3(n-3) contents. Microphytobenthos was slightly more 13 C-depleted (−15.4‰) and had high levels of diatom markers: 14:0, 16:1(n-7)c, 20:5(n-3). Low mean δ 13 C (−22.0‰) and large amounts of diatom and bacteria (18:1(n-7)c) markers indicated that SPOM was mainly composed of a mixture of fresh and decayed pelagic diatoms. Higher mean δ 13 C (−17.9‰) and high amounts of diatom FAs were found in SSOM, showing that microphytobenthic diatoms dominate. Very low percentages of 18:2(n-6) and 18:3(n-3) in consumers indicated a low contribution of Z. noltii material to their diets. Grazers, deposit and suspension-deposit feeders had δ 13 C close to microphytobenthos and high levels of diatom FAs, confirming that microphytobenthos represented the main part of their diet. Lower δ 13 C and higher amounts of flagellate FAs-22:6(n-3) and 16:4(n-3)-in suspension feeders indicated that their diet resulted from a mixture of SPOM and microphytobenthos. These results demonstrate that invertebrates do not consume high amounts of seagrass and highlight the main role of benthic diatoms in this intertidal seagrass bed.

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Section: Influence Of Phytoplanktonic Materialssupporting

confidence: 61%

Trophic importance of diatoms in an intertidal Zostera noltii seagrass bed: Evidence from stable isotope and fatty acid analyses

Lebreton

Richard

Galois

et al. 2011

Estuarine, Coastal and Shelf Science

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“…To date, there are not enough data to support a clear explanation for PNF ingestion of bacteria at a given site. A range of environmental factors (nutrients, light, prey abundance) may all affect the abundance and feeding behavior of PNF (Bird & Kalff 1986, Salonen & Jokinen 1988, Caron et al 1993, Nygaard & Tobiesen 1993, Holen 1999, Sanders et al 2000, Moorthi & Berninger 2006, Unrein et al 2007). In most cases, photosynthesis would presumably be the primary energy source for these PNF, while phagotrophy would allow them to compete successfully with non-phagotrophic algae for growth-limiting nutrients.…”

Section: Discussionmentioning

confidence: 99%

“…However, a range of environmental factors, including light, prey abundance and nutrients, can affect the feeding behavior of PNF and it is unlikely that there is a single explanation or a universal stimulus for the ingestion of particles by PNF (Bird & Kalff 1986, Salonen & Jokinen 1988, Caron et al 1993, Nygaard & Tobiesen 1993, Holen 1999, Moorthi & Berninger 2006, Unrein et al 2007). In some studies, PNF feeding rates have been found to increase in low-light conditions or in darkness (Hall et al 1993, Holen 1999), but to decrease under limited light conditions in other studies (Caron et al 1993, Jones & Rees 1994.…”

Section: Introductionmentioning

confidence: 99%

Importance of bacterivory by pigmented and heterotrophic nanoflagellates during the warm season in a subtropical western Pacific coastal ecosystem

Tsai¹,

Gong²,

Sanders³

et al. 2011

Aquat. Microb. Ecol.

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We investigated temporal variations in the effects of bacterivory by different sizes of heterotrophic nanoflagellates (HNF) and pigmented nanoflagellates (PNF) during a warm period (May to September) in oligotrophic coastal waters of the subtropical western Pacific. Short-term experiments with fluorescently labeled bacteria (FLB) demonstrated ingestion rates of 0.3 to 5.8 bacteria HNF -1 h -1 by HNF in the size range 3-6 µm -rates that were higher than observed for other sizes of HNF. Rates of ingestion by PNF ranged between 0.9 and 15.5 cells PNF -1 h -1, and, as for HNF, were greatest for PNF in the 3-6 µm size group. Nanoflagellates of size < 6 µm removed about 98% of the total amount of bacteria consumed. The 3-6 µm PNF, 2-3 µm HNF, and 3-6 µm HNF were major consumers in the nanoflagellate community and were responsible for an average of 52, 28 and 16% of the total consumption of bacteria, respectively. The smallest PNF (2-3 µm) consumed only about 2% of the total and were considered to be primarily autotrophic. Despite ingestion rates in the range of those reported elsewhere, the low abundance of nanoflagellates observed resulted in relatively low grazing impacts (<10% of bacterial standing stock). We found a significant negative correlation between PO 4 concentrations and ingestion rates of the 3-6 µm PNF, suggesting that the PNF ingestion rate increased under nutrient-deficient conditions.

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“…However, growth physiology is difficult to trace in natural assemblages and therefore several different methods have been developed to establish mixotrophic status, each with their own advantages and biases [31,65]. Available techniques include basic identification as a predatory mixotroph via visualization methods such as microscopy and flow cytometry, sometimes in connection with stains targeting acidic food vacuoles [66] and incubations with labelled prey [18,51,67,68]. Stable isotope probing (SIP), wherein a prey population carrying an isotopic signature is incubated with wild communities to detect prey assimilation into nucleic acids [69,70], can be used to detect predatory activity in putative mixotrophs.…”

Section: Using Cultures To Characterize Mixotrophymentioning

confidence: 99%

The need to account for cell biology in characterizing predatory mixotrophs in aquatic environments

Wilken

Yung

Hamilton

et al. 2019

Phil. Trans. R. Soc. B

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Photosynthesis in eukaryotes first arose through phagocytotic processes wherein an engulfed cyanobacterium was not digested, but instead became a permanent organelle. Other photosynthetic lineages then arose when eukaryotic cells engulfed other already photosynthetic eukaryotic cells. Some of the resulting lineages subsequently lost their ability for phagocytosis, while many others maintained the ability to do both processes. These mixotrophic taxa have more complicated ecological roles, in that they are both primary producers and consumers that can shift more towards producing the organic matter that forms the base of aquatic food chains, or towards respiring and releasing CO 2 . We still have much to learn about which taxa are predatory mixotrophs as well as about the physiological consequences of this lifestyle, in part, because much of the diversity of unicellular eukaryotes in aquatic ecosystems remains uncultured. Here, we discuss existing methods for studying predatory mixotrophs, their individual biases, and how single-cell approaches can enhance knowledge of these important taxa. The question remains what the gold standard should be for assigning a mixotrophic status to ill-characterized or uncultured taxa—a status that dictates how organisms are incorporated into carbon cycle models and how their ecosystem roles may shift in future lakes and oceans. This article is part of a discussion meeting issue ‘Single cell ecology’.

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Mixotrophic nanoflagellates in coastal sediments in the western Baltic Sea

Cited by 7 publications

References 39 publications

Trophic importance of diatoms in an intertidal Zostera noltii seagrass bed: Evidence from stable isotope and fatty acid analyses

Trophic importance of diatoms in an intertidal Zostera noltii seagrass bed: Evidence from stable isotope and fatty acid analyses

Importance of bacterivory by pigmented and heterotrophic nanoflagellates during the warm season in a subtropical western Pacific coastal ecosystem

The need to account for cell biology in characterizing predatory mixotrophs in aquatic environments

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