Zooplankton feeding on seston in the Rhone River plume area (NW Mediterranean Sea) in May 1988

Gaudy, R.; Pagano, Marc; Lochet, François

doi:10.1007/bf00041462

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…Mississippi River plume, Lohrenz et al 1990, Gulf of Papua, Davies 2004). This interface is also associated with high concentrations of micro-zooplankton (Gaudy 1990). During the Biodypar Cruise 4, a significant enhancement of bacterial abundance and chlorophyll concentration, as well as production, were measured in the salinity range 29 to 36 (trajectory D112) and 26 to 34 (trajectory D120) (Fig.…”

Section: Discussionmentioning

confidence: 90%

Impact of phytoplankton and bacterial production on nutrient and DOM uptake in the Rhône River plume (NW Mediterranean)

Pujo‐Pay¹,

Conan²,

Joux³

et al. 2006

Mar. Ecol. Prog. Ser.

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From April 1998 to April 1999, 4 cruises were conducted to investigate the evolution of physical and biological characteristics of the Rhône River plume. Particular emphasis was placed on the relationships between phytoplanktonic or bacterial production and environmental conditions. For most of the year, distributions of nutrients, phytoplankton and bacterial activities were conservative along the salinity gradient, indicating the dominance of physical dilution processes. In April 1999, nutrient-salinity relationships showed strong deviations from the conservative mixing line which were associated with a phytoplankton bloom. Deviations from the conservative mixing line were used to estimate the relative contributions of physical and biological processes in the removal of riverine derived material. During the phytoplankton bloom, there was a specific organisation of the microbial populations and their activities at intermediate salinity. Maximal productions were associated with maxima in ammonium and phosphate uptake rates for bacteria, but with maxima in nitrate uptake rates for phytoplankton. The relative accumulation of dissolved organic carbon (DOC) and nitrogen (DON) at high salinity, and the seasonal variability in their distribution, resulted in a potential competition between bacteria and phytoplankton for key mineral nutrients highlighted by an increase in the DOC:DON ratio up to 10. This study contributes to our understanding of the relationship between phytoplankton, bacteria and dissolved organic matter and helps to elucidate the factors controlling the productivity of the system. In particular, the impact of wind and riverine output need to be considered alongside seasonal variability in the chemical and hydrodynamic environment.

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Section: Discussionmentioning

confidence: 90%

Impact of phytoplankton and bacterial production on nutrient and DOM uptake in the Rhône River plume (NW Mediterranean)

Pujo‐Pay¹,

Conan²,

Joux³

et al. 2006

Mar. Ecol. Prog. Ser.

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“…organic detritus, lithogenic particles) of varying quality and sizes. Although plumes are regarded to offer generally favorable feeding conditions for zooplankton, additions of lithogenic particles and detritus can lower the nutritional value of individual food particles despite higher standing stocks of the bulk material overall (Gaudy et al 1990;Pagano et al 1993). Zooplankton consumers are therefore expected to feed selectively on high-quality, fresh phytoplankton production to optimize their energy intake (sensu Tackx et al 2003).…”

Section: Discussionmentioning

confidence: 99%

Can export of organic matter from estuaries support zooplankton in nearshore, marine plumes?

et al. 2008

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Marine and terrestrial ecosystems are connected via transfers of nutrients and organic matter in river discharges. In coastal seas, such freshwater outflows create prominent turbidity plumes. These plumes are areas of high biological activity in the pelagos, of which zooplankton is a key element. Conceptually, the increased biomass of zooplankton consumers in plumes can be supported by two alternative trophic pathways-consumption of fresh marine phytoplankton production stimulated by riverine nutrients, or direct trophic subsidies through the uptake of terrestrial and estuarine organic matter flushed to sea. The relative importance of these two pathways has not been established previously. Isotopic tracing (carbon and nitrogen) was used to measure the extent of incorporation of marine versus terrestrial matter into mesozooplankton consumers in the plumes off a small estuary in eastern Australia. Replicate zooplankton samples were taken during baseflow conditions with minimal freshwater influence to the sea, and during pulsed discharge events that generated turbidity plumes in coastal waters. Food sources utilized by zooplankton differed among locations and with the strength of freshwater flow. Terrestrial and estuarine carbon only made a sizeable contribution (47%) to the carbon demands of zooplankton in the lower estuary during pulsed freshwater flows. By contrast, in plumes that developed in nearshore marine waters, phytoplankton supplied up to 90% of the dietary carbon of zooplankton feeding in the plumes. Overall, it was ''fresh'' carbon, fixed by marine phytoplankton, the growth of which became stimulated by fluvial nutrient exports, that dominated energy flows in plume regions. The trophic role of terrestrial and estuarine organic exports was comparatively minor. The trophic dynamics of plankton in small coastal plumes is closely linked to variations in freshwater flow, but this coupling operates mainly through the enhancement of in-situ phytoplankton production rather than cross-boundary transfers of organic matter to marine food webs in the pelagos.

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“…At this time, the cold low salinity surface plume water had higher particle volumes, NH4 concentrations, and bacterial biomass than the underlying marine stratum . Such characteristics, partly resulting from the influence of freshwater inflow, have already been described in the Rhone River area (Blanc et al, 1969 ;Loeillet & Leveau, 1985 ;Soto & Bianchi, 1988 ;Kirchman et al, 1989 ;Gaudy et al ., 1990) . The increase in wind speed observed around 02 .00 h induced the lateral shifting of the plume .…”

Section: Mesozooplanktonmentioning

confidence: 89%

“…The Rhone River plume boundary also has high chlorophyll concentration and primary production (Videau & Leveau, 1990) that create optimal food conditions for mesozooplankton (Gaudy et al ., 1990) and for bacterial production (Kirchman et al ., 1989 ;Bianchi et al ., 1993).…”

Section: Introductionmentioning

confidence: 99%

Cross frontal variability in hydrological and biological structures observed in a river plume area (Rh�ne mouth, NW Mediterranean Sea)

et al. 1996

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In the Rhone River plume area, NH4, DFAA, seston particles, bacteria, flagellates and mesozooplankton were studied over 24 hours at a fixed station . Variations of both abiotic and biotic variables demonstrated rapid changes in vertical structure, from stratified towards mixed . This evolution was related to hydrodynamical changes caused by wind . Strong variability resulting from hydrological changes was apparent in surface water where the plume edge crossed the station as evident by sharp increase in particle volume (20-25 am ESD range), NH4 (from 9 to 12 pM) and DFAA (from 1 to 3 pM) concentrations . This frontal ecosystem favored fast growing organisms such as bacteria of which densities reached 19 and production 0 .22-0 .26 pg C 1-1 h -1 , and flagellates which showed densities of 1 .5 to 2 pg C 1 -1 . Among DFAA, the relative concentration (mole %) of serine increased from 13 .3% in the plume water to 44-45% in the front system . The biomass and feeding activity of zooplankton also increased at the plume boundary.

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Zooplankton feeding on seston in the Rhone River plume area (NW Mediterranean Sea) in May 1988

Cited by 8 publications

References 29 publications

Impact of phytoplankton and bacterial production on nutrient and DOM uptake in the Rhône River plume (NW Mediterranean)

Impact of phytoplankton and bacterial production on nutrient and DOM uptake in the Rhône River plume (NW Mediterranean)

Can export of organic matter from estuaries support zooplankton in nearshore, marine plumes?

Cross frontal variability in hydrological and biological structures observed in a river plume area (Rh�ne mouth, NW Mediterranean Sea)

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