Grazing impact on chromophoric dissolved organic matter (CDOM) by the larvacean Oikopleura dioica

Urban-Rich, Juanita; Fernández, Diego; Acuña, José Luis

doi:10.3354/meps317101

Cited by 11 publications

(8 citation statements)

References 33 publications

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“…A small O. dioica (120-mm) feeds optimally on particles between 0.45 mm and 2.5 mm but has a total feeding range from 0.04 mm to 24 mm. This is consistent with the observation that appendicularians may feed on large dissolved organic molecules, although with low efficiency (Urban-Rich et al 2006).…”

Section: Discussionsupporting

confidence: 92%

Active prey rejection in the filter‐feeding appendicularian Oikopleura dioica

Lombard

Selander

Kiørboe

2011

Limnology & Oceanography

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We describe different modes of prey rejection in a filter‐feeding appendicularian, Oikopleura dioica. Nonselective prey rejection occurs by intermittent rejection through reversal of the feeding current of all particles when the pharyngeal filter is overloaded, and by accidental loss through the spiracles of all particles that have entered the house when the pharyngeal filter occasionally breaks. In addition, selective prey rejection of individual particles may occur in the mouth by reversal of the ciliary current in the spiracle: the unwanted particle is expelled with a small amount of water. Up to four rejections of individual particles may occur per second. This active rejection is based on both the size and the chemical characteristics of the individual particle. A significantly higher rejection rate was found for toxic dinoflagelate (68%) compared to similar sized nontoxic ones (34%); exponentially growing algae were less rejected than senescent ones; and nutrient‐depleted algae were more rejected than nutrient‐replete cells. For nontoxic particles, prey size relative to the size of the appendicularian was the main prey selection criterion and the optimal prey size (> 80% acceptance) for O. dioica is between 0.4% and 2% of their own size, whereas the minimum and maximum particle sizes that they can ingest range from 0.04% to 20% of their own size. This prey size spectrum is much broader than that found in most other planktivorous organisms and demonstrates that appendicularians are simultaneous microphageous and macrophageous planktonic grazers.

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Section: Discussionsupporting

confidence: 92%

Active prey rejection in the filter‐feeding appendicularian Oikopleura dioica

Lombard

Selander

Kiørboe

2011

Limnology & Oceanography

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“…[] found evidences to support that marine CDOM is composed of a major terrestrial component, founding the increase of CDOM fluorescence with AOU on the charge‐transfer model of Del Vecchio and Blough [], which proposed that the fluorescence signal of DOM is in part due to intramolecular charge‐transfer interactions between electron donors and acceptors formed through the partial oxidation of lignin and other aromatic polymeric precursors of terrestrial origin. On the contrary, other studies demonstrated that marine CDOM is generated in situ from bacterioplankton during its active growth [ Kramer and Herndl , ; Ortega‐Retuerta et al ., ], as well as directly by phytoplankton via extracellular release [ Romera‐Castillo et al ., ] or indirectly by zooplankton grazing [ Urban‐Rich et al ., ]. Recently, Jørgensen et al .…”

Section: Discussionmentioning

confidence: 99%

Water mass age and aging driving chromophoric dissolved organic matter in the dark global ocean

Catalá

Reche

Álvarez

et al. 2015

Global Biogeochemical Cycles

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The omnipresence of chromophoric dissolved organic matter (CDOM) in the open ocean enables its use as a tracer for biochemical processes throughout the global overturning circulation. We made an inventory of CDOM optical properties, ideal water age (τ), and apparent oxygen utilization (AOU) along the Atlantic, Indian, and Pacific Ocean waters sampled during the Malaspina 2010 expedition. A water mass analysis was applied to obtain intrinsic, hereinafter archetypal, values of τ, AOU, oxygen utilization rate (OUR), and CDOM absorption coefficients, spectral slopes and quantum yield for each one of the 22 water types intercepted during this circumnavigation. Archetypal values of AOU and OUR have been used to trace the differential influence of water mass aging and aging rates, respectively, on CDOM variables. Whereas the absorption coefficient at 325 nm (a 325 ) and the fluorescence quantum yield at 340 nm (Φ 340 ) increased, the spectral slope over the wavelength range 275-295 nm (S 275-295 ) and the ratio of spectral slopes over the ranges 275-295 nm and 350-400 nm (S R ) decreased significantly with water mass aging (AOU). Combination of the slope of the linear regression between archetypal AOU and a 325 with the estimated global OUR allowed us to obtain a CDOM turnover time of 634 ± 120 years, which exceeds the flushing time of the dark ocean (>200 m) by 46%. This positive relationship supports the assumption of in situ production and accumulation of CDOM as a by-product of microbial metabolism as water masses turn older. Furthermore, our data evidence that global-scale CDOM quantity (a 325 ) is more dependent on aging (AOU), whereas CDOM quality (S 275-295 , S R , Φ 340 ) is more dependent on aging rate (OUR).

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“…Appendicularians use three filters: the inlet filter located at the two entries of the house, the foodconcentrating filter in the center of the house, and a pharyngeal filter continually secreted inside the pharyngeal cavity. During the filtration process, only the two filters located in the house have an effect on the size of particles retained: the food-concentrating filter, which has mesh sizes , 0.2 mm (Flood and Deibel 1998), allows retention of small particles such as phytoplankton (Acuñ a et al 2002), bacteria (Zubkov and Lòpez-Urrutia 2003), colloidal matter (Flood et al 1992), and even dissolved organic matter (Urban-Rich et al 2006). In contrast, the inlet filter retains the large particles outside of the house.…”

Section: Discussionmentioning

confidence: 99%

Experimental and modeling evidence of appendicularian‐ciliate interactions

Lombard

Eloire

Gobet

et al. 2009

Limnology & Oceanography

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Interactions between appendicularians and ciliates were observed over the life span of Oikopleura dioica in laboratory cultures and clarified with the use of mathematical modeling and microscopic observations. Complex interactions including competition, parasitism, predation, and histophagy occurred simultaneously, resulting in apparent mutualism. The large ciliate Strombidium sp. entered the inlet filters of appendicularian houses (larger than 500 mm body size) by distorting the mesh. Once inside, Strombidium fed on particles concentrated on the filters. When appendicularians were larger than 900 mm, both the high flow rate in the buccal tube and their esophagus width allowed the ''host'' appendicularian to capture and ingest ciliates. Thus, ciliates seem to be sequentially competitors, then parasites or commensal in appendicularian houses, and finally prey for appendicularians. Appendicularian rates of somatic growth and reproduction were enhanced when ciliates were ingested. This additional food supply could be essential in oligotrophic environments. Reciprocally, appendicularians support higher ciliate growth rates, allowing ciliates to survive and grow in food-limited environments. Appendicularians thus modify the size spectrum of the microbial food web both by removing small organisms (0.2-30 mm) and enhancing the growth of mid-sized and large ciliates.

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Grazing impact on chromophoric dissolved organic matter (CDOM) by the larvacean Oikopleura dioica

Cited by 11 publications

References 33 publications

Active prey rejection in the filter‐feeding appendicularian Oikopleura dioica

Active prey rejection in the filter‐feeding appendicularian Oikopleura dioica

Water mass age and aging driving chromophoric dissolved organic matter in the dark global ocean

Experimental and modeling evidence of appendicularian‐ciliate interactions

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