Microzooplankton grazing in the Estuary of Mundaka, Spain, and its impact on phytoplankton distribution along the salinity gradient

Ruiz, Asier; Franco, Javier; Villate, Fernando

doi:10.3354/ame014281

Cited by 34 publications

(19 citation statements)

References 21 publications

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“…Studies of the in situ grazing of E. affinis in the Gironde Estuary have shown that the concentration of suspended particulate matter had no effect on phytoplankton ingestion in this species (Irigoien et al 1993). Several studies which support our hypothesis have shown that microzooplankton herbivory represents from 50 to 80% of potential phytoplankton primary production and is an important sink for estuarine phytoplankton production (McManus & Ederington 1992, Froneman & McQuaid 1997, Ruiz et al 1998, Lehrter et al 1999.…”

Section: Effect Of Grazingsupporting

confidence: 70%

Trophic coupling across the St. Lawrence River estuarine transition zone

Winkler¹,

Dodson²,

Bertrand³

et al. 2003

Mar. Ecol. Prog. Ser.

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Section: Effect Of Grazingsupporting

confidence: 70%

Trophic coupling across the St. Lawrence River estuarine transition zone

Winkler¹,

Dodson²,

Bertrand³

et al. 2003

Mar. Ecol. Prog. Ser.

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“…Caron 2001). In the present work, as in previous studies of herbivory rates in the Urdaibai estuary (Cotano et al 1998, Ruiz et al 1998, no nutrients were added, because phytoplankton are not nutrient limited, at least in the upper zone of the estuary. Some nutrient limitation may occur in the lower estuary, but we decided not to add nutrients to avoid introducing other uncertainties.…”

Section: Methods For Measuring Bacterivory and Herbivorymentioning

confidence: 79%

“…3 dilution fractions (Gallegos 1989). As in previous measurements of herbivory rates in the Urdaibai estuary, no nutrients were added (see Cotano et al 1998, Ruiz et al 1998). The biomass of chl a and the percentage standing stock of phytoplankton consumed daily were estimated as in Boissonneault-Cellineri et al (2001).…”

Section: Methodsmentioning

confidence: 99%

Short-term variability in microbial food web dynamics in a shallow tidal estuary

Iriarte¹,

Madariaga²,

Revilla³

et al. 2003

Aquat. Microb. Ecol.

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Short-term variability in microbial food web dynamics was investigated from 3 to 17 May 2001 at 2 contrasting sites in the Urdaibai estuary (Bay of Biscay). The lower site is located in an area where tidal advection exerts a major influence, whereas the upper site is located in area where the influence of the tide is much lower and that of river runoff is markedly higher than at the lower site. The biomass of microbial plankton (phytoplankton, bacteria, non-pigmented flagellates [NPF] and ciliates) and their rates of activities (primary production, bacterial production, herbivory, bacterivory and microbial community respiration) were markedly higher at the upper site, thus showing that tidal flushing is a key factor controlling these spatial differences along the longitudinal axis of the estuary, rendering the upper channel a high productivity zone and the lower euhaline area a less productive one. Water residence time also exerted an overriding effect on chlorophyll a distribution on a temporal basis, with drastic increases in river runoff, due to heavy rain pulses, being responsible for immediate bloom dispersion in the upper channel. Bacterial density was less affected than phytoplankton biomass by increased river flow. It is hypothesised that detrital material increases caused by increases in river runoff provided an extra source of carbon for bacterial growth. On average, microbial herbivory was responsible for the fate of ca. 50% of chlorophyll a standing stock. Herbivory rates were not significantly different on phytoplankton < 8/> 0.2 µm and on those <100/> 8 µm in size and grazing pressure on phytoplankton was lower in the more productive site. Protists 1 to 8 µm in size were the main bacterivores. No synchrony was observed between bacterial and NPF abundances. Instead a lag phase was observed between the peak densities of bacteria and NPF, which was larger at the more productive upper site than in the lower estuary and allowed bacteria in the former zone to exploit substrate availability without significant grazing control for several days. Microbial community rate of respiration was significantly correlated with bacterivory rates and NPF abundance in the upper estuary, but not in the lower zone. The median of the proportion of bacterial production removed by bacterivory was 64% at the lower estuary station and 17% in the upper estuary. A possible explanation for this difference could be that attached bacteria (abundant in the upper reaches of the estuary) are less accessible for protistan grazing. Bacterivory by protists accounted for a mean of 14 and 7% of protistan herbivory at the lower and upper sites respectively.

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“…3, there is no apparent trend for the transformed m : ratios as a function of initial concentration of Chl a. At the very high end of the chlorophyll values, the data are dominated by a single study (Ruiz et al 1998;Mundaka Estuary). These are plotted at 62 g Chl a L Ϫ1 , the mean chlorophyll estimate, because concentrations were not reported for individual experiments.…”

Section: Resultsmentioning

confidence: 92%

Phytoplankton growth, microzooplankton grazing, and carbon cycling in marine systems

Calbet

Landry

2004

Limnology & Oceanography

991

721

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We present an analysis of the global impact of microplanktonic grazers on marine phytoplankton and its implications for remineralization processes in the microbial community. The data were obtained by an extensive literature search that yielded 788 paired rate estimates of autotrophic growth () and microzooplankton grazing (m) from dilution experiments. From studies in which phytoplankton standing stock was measured in terms of carbon equivalents, we show that the production estimate from dilution experiments is a reasonable proxy (r ϭ 0.89) for production determined by the standard 14 C method. The ratio m : , the proportion of primary production (PP) consumed by micrograzers, shows that microzooplankton consumption is the main source of phytoplankton mortality in the oceans, accounting for 67% of phytoplankton daily growth for the full data set. This ratio varies modestly among various marine habitats and regions, with data averages ranging from 60% for coastal and estuarine environments to 70% for the open oceans, and from ϳ59% for temperate-subpolar and polar systems to 75% for tropical-subtropical regions. Given estimates for the metabolic requirements of micrograzers and assuming they consume most bacterial production, regionally averaged estimates of the protistan respiration are 35-43% of daily PP for the first level of consumer or 49-59% of PP for three trophic transfers. The estimated contributions of microbial grazers to total community respiration are of the same magnitude as bacterial respiration. Consequently, potential ecosystem differences in micrograzer activity or trophic structure are a large uncertainty for biogeochemical models that seek to predict the microbial community role in carbon cycling from bacterial parameters alone.

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Microzooplankton grazing in the Estuary of Mundaka, Spain, and its impact on phytoplankton distribution along the salinity gradient

Cited by 34 publications

References 21 publications

Trophic coupling across the St. Lawrence River estuarine transition zone

Trophic coupling across the St. Lawrence River estuarine transition zone

Short-term variability in microbial food web dynamics in a shallow tidal estuary

Phytoplankton growth, microzooplankton grazing, and carbon cycling in marine systems

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