Standing stock and dynamics of picophytoplankton in the Thau Lagoon (northwest Mediterranean coast)

Vaquer, André; Troussellier, Marc; Courties, Claude; Bibent, Bertrand

doi:10.4319/lo.1996.41.8.1821

Cited by 98 publications

(87 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The larger sized chromophytic rbcL mRNA values found here were presumably caused by diatoms, which are abundant in these waters. A similar size distribution of autotrophs was found in the Thau Lagoon in the Mediterranean (Vaquer et al 1996) and in coastal Gulf of Mexico waters under the influence of the Tampa Bay plume (Pichard et al 1997a). In the latter environment, 43% of the carbon fixation was associated with particles Ͻ1 m in size, with 25 and 31% associated with particles Ͼ5 and 1-5 m, respectively.…”

Section: Size Distribution Of Rubisco Gene Expression In Coastal Watementioning

confidence: 50%

Evidence for a clade‐specific temporal and spatial separation in ribulose bisphosphate carboxylase gene expression in phytoplankton populations off Cape Hatteras and Bermuda

Paul

Pichard

Kang

et al. 1999

Limnology & Oceanography

View full text Add to dashboard Cite

The factors affecting the regulation of photosynthetic carbon fixation in diverse phytoplankton populations are not yet understood. To this end, we have measured the expression of the gene (rbcL) for the major carbon fixation enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase, in coastal phytoplankton populations off Cape Hatteras and in oligotrophic oceanic picoplankton near Bermuda. Using gene probes specific for the cyanobacterial/chlorophytic clade and the chromophytic clade (diatoms, chrysophytes, prymnesiophytes, and others) of Form I rbcL genes (''cyano'' and ''chromo'' probes, respectively), we have measured rbcL messenger ribonucleic acid (mRNA) levels in size-fractionated coastal waters, in a decktop diel incubator and a Lagrangian drifter study, and in vertical profiles in stratified, oligotrophic ocean water. In coastal waters influenced by estuarine plumes, an equal distribution of carbon fixation between the picoplankton and the micro/nannoplankton occurred, with cyano rbcL mRNA coinciding with Synechococcus counts in the Ͻ1-m fraction, with the majority of the chromo rbcL mRNA expression occurring in the larger sized phytoplankton fraction. In profiles of oligotrophic oceanic waters, the cyano rbcL mRNA was found in the upper water column (ϳ50-m depth) and coincided with peaks in Synechococcus counts. The chromo rbcL mRNA was concentrated at the subsurface chlorophyll a (Chl a) maximum (ϳ85 m) and corresponded to red-fluorescing cell counts, thought to be picoeucaryotes and diatoms. Photosynthetic carbon fixation and RUBISCO enzyme activity encompassed both cyano and chromo rbcL mRNA peaks, suggesting a near equal contribution to carbon fixation in the water column by these two phytoplankton clades. Both decktop diel incubator studies and a Lagrangian drifter study in coastal waters indicated cyano rbcL transcription in the morning and chromophytic rbcL transcription in the late afternoon/early evening. Thus, the two major clades of RUBISCOcontaining phytoplankton occupy separate niches in time, space, and cell size in the waters off Cape Hatteras. The factors determining such clade-specific niches may include efficiency of nutrient utilization, differences in relative carboxylase/oxygenase activity ( values) of cyano (Form IB) and chromophytic (Form ID) RUBISCOs, and differences in pigment composition/adaptation to light regimes. Additionally, we propose that chromo rbcL mRNA may be indicative of new production, whereas cyano rbcL mRNA correlates with recycled production in stratified, oligotrophic oceanic environments.Although photosynthetic carbon fixation is one of the most important biological processes occurring in the ocean, little is known concerning the molecular regulation of this process in natural phytoplankton assemblages. The enzyme responsible for the vast majority of photosynthetic carbon fixation by phytoplankton is ribulose bisphosphate carboxylase/oxygenase (RUBISCO) (Raven 1993). There is evidence for ␤-carboxylation (Descolas- Gros and Fontugne 1985;Colman 1989;C...

show abstract

Section: Size Distribution Of Rubisco Gene Expression In Coastal Watementioning

confidence: 50%

Evidence for a clade‐specific temporal and spatial separation in ribulose bisphosphate carboxylase gene expression in phytoplankton populations off Cape Hatteras and Bermuda

Paul

Pichard

Kang

et al. 1999

Limnology & Oceanography

View full text Add to dashboard Cite

show abstract

“…In seasons other than mid-summer, picoeukaryotes are probably essential components of the community in the study area. The importance of picoeukaryotes has been demonstrated in various studies of coastal waters (Vaquer et al 1996, Bec et al 2005, Worden et al 2004.…”

Section: Evaluation Of Picoplankton Biomassmentioning

confidence: 99%

Seasonal variations in abundance and biomass of picoplankton in an oyster-farming area of northern Japan

Kamiyama

Iwai²,

Hamasaki

2009

Plankton Benthos Res

View full text Add to dashboard Cite

“…Samprocess to study. The enhancement of pelagic pripling stations are also described in Gilbert et al (1997), mary production by bottom anoxia cannot be studied Souchu et al (1997) and Vaquer et al (1997). Sediby isolating a small volume of water from the rest of ments were studied before (June), during (August) and the water column.…”

Section: Introductionmentioning

confidence: 99%

Biogeochemical aspects of bottom anoxia in a Mediterranean lagoon (Thau, France)

Souchu¹,

Gasc²,

Collos³

et al. 1998

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

Physical and chemical characteristics (temperature, salinity, dissolved oxygen), nutrients [dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP) and silicate], dissolved organic nitrogen (DON) and phosphorus and particulate matter [particulate organic carbon (POC) and nitrogen (PON) and chlorophyll a] were measured at a station located in the deepest part of the Thau lagoon (8.5 m), France, during a 10 d period of bottom anoxia in summer 1994. The upper 8 cm of sediment were also analyzed for ammonium (NH,') and SRP concentrations in the pore.water. The study period was characterized by mean wlnd speed under 4 m S-' which induced an increase of surface temperature from 18 to 2g°C with the formation of a thermocline. The correlation (p < 10-4) between the wind speed averaged over the previous day and the difference between bottom and surface temperatures showed that the wind conshtuted the main vector of vertical mixing. The lack of wind led to dissolved oxygen depletion in the bottom 2 m and to a strong porosity increase in the upper 10 cm of sediment (80 to >95%). Anoxic conditions increased NH,+ and SRP concentrations in porewater from 231 + 89 to 1305 + 305 (+ SD) ).]M and from 6.6 + 0.8 to 108 t 43 PM respectively. The potential increase of NH,' concentrations in porewater estimated from the mineralization of the microphytobenthos explained 30% of the measured increase in the upper 8 cm of porewater. The study period was characterized by an increase in NH4+, SRP and dissolved Si concentratlons in the bottom water column (maxima respectively 24.2, 4.9 and 57 PM). Linear regressions between nutrient concentrations in the water column and temperature revealed a strong enhancement of bottom fluxes during anoxia. Nitrate + nitrite (No3-+ NO2-) were absent in anoxic waters and remained below 0.5 pM in oxic waters. Monthly concentrations of SRP in the water column of the Thau lagoon from 1970 to 1994 revealed anoxia events by summer peak values corresponding to strong bottom anoxia. Nevertheless, the general trend was a decrease due to the gradual control of eutrophication which should lead to the disappearance of bottom anoxia within the next decade. A fraction of the nutrients of benthic origin was transformed into planktonic particulate matter vla prlmary production whlch increased the concentrations of chl a from about 1 to 15 pg I-'. Concentrations of DON and PON in the water column were significantly correlated, suggest~ng that DON compounds were released by the pelagic food web but not directly by the sediment. The increase of total nitrogen (DIN + DON + PON), considering the water column as a closed box during 10 d of winds under 5 m S-', was estimated at 1.7 pm01 N 1-' d-' and would correspond to a benthic flux of 600 pm01 N m-2 h-' for 10 d.

show abstract

Standing stock and dynamics of picophytoplankton in the Thau Lagoon (northwest Mediterranean coast)

Cited by 98 publications

References 19 publications

Evidence for a clade‐specific temporal and spatial separation in ribulose bisphosphate carboxylase gene expression in phytoplankton populations off Cape Hatteras and Bermuda

Evidence for a clade‐specific temporal and spatial separation in ribulose bisphosphate carboxylase gene expression in phytoplankton populations off Cape Hatteras and Bermuda

Seasonal variations in abundance and biomass of picoplankton in an oyster-farming area of northern Japan

Biogeochemical aspects of bottom anoxia in a Mediterranean lagoon (Thau, France)

Contact Info

Product

Resources

About