Spatial variability of phytoplankton, bacteria and viruses in the mesotidal salt wedge Douro Estuary (Portugal)

Bordalo, Adriano A.; Vieira, Mário E. C.

doi:10.1016/j.ecss.2004.11.003

Cited by 34 publications

(27 citation statements)

References 48 publications

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“…This suggests that the upper estuary is more productive than the lower estuary as a result of higher nitrogen concentrations from riverine origin (Mallin et al, 1993;Malej et al, 1995). Also, higher chlorophyll biomass from the reservoir (Bordalo and Vieira, 2005) may help to explain these trends, but to a lesser extent (Table 5). Regarding temporal differences, higher PP values were associated to higher temperatures, lower light extinction coefficients (k ) and higher P max , coinciding with the summer period.…”

Section: Discussionmentioning

confidence: 92%

“…During winter, high flows often prevent coastal water from entering into the estuary, even during the flood, raise nutrient levels, lower phytoplankton biomass and reduce water residence time. In this estuarine system, river flow rather than tides controls water residence time (Bordalo and Vieira, 2005). The surveys were carried out during a wet year, since the average river discharge was almost twice the long-term average inflow of freshwater.…”

Section: Discussionmentioning

confidence: 99%

“…River flows present a large inter-annual variability, with considerable differences between wet and dry years. A decrease of annual flow has been reported, due to climate phenomena (Trigo et al, 2004) but also to an increase of water storage for hydroelectric power generation, agriculture and domestic consumptions (Bordalo and Vieira, 2005). The fact that freshwater flowing into the estuary originates in a reservoir, a semilotic ecosystem, may also influence estuarine metabolism due to specific phytoplankton characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…The fact that freshwater flowing into the estuary originates in a reservoir, a semilotic ecosystem, may also influence estuarine metabolism due to specific phytoplankton characteristics. Moreover, in the case of the Douro, the last dam is the main source of phytoplankton biomass (Bordalo and Vieira, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Pelagic metabolism of the Douro estuary (Portugal) – Factors controlling primary production

Azevedo

Duarte

Bordalo

2006

Estuarine, Coastal and Shelf Science

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The pelagic metabolism of the Douro estuary (Portugal) and the factors influencing primary production (PP) and community respiration (CR) in this system were studied during an annual cycle (December 2002eDecember 2003. Sampling surveys were conducted twice a month during ebb and flood spring tides and water samples were collected for PP and CR assessments at three stations along the estuary (lower, middle and upper stretches). During the study period, PP values were in the range of 4.7e1878.5 mg C m ÿ2 d ÿ1 (average, 319.9 mg C m ÿ2 d ÿ1 ). River discharge controlled phytoplankton biomass inputs into the estuary as well as residence time. A decreasing trend in water column PP from the upper to the lower estuary related to higher nitrogen concentrations and phytoplankton biomass from riverine origin was observed. An inverse trend was found for CR, i.e., higher values were found in the lower, more urbanized stretch. During the study period, averaged CR values reached 1154 mg C m ÿ2 d ÿ1 . In general, heterotrophy dominated the entire estuary, except in the upper stretch from May through July, when increased PP, but also lower CR values were recorded. A positive correlation between chlorophyll a and P max was found which is unusual in coastal ecosystems, where a decreasing trend of the P/B ratio as a function of net primary production is generally observed. This could be explained by the relatively low phytoplankton biomass, preventing intraspecific competition from lowering photosynthetic capacity, on one hand, and the physiology of phytoplankton related to their origin in a semi-lotic (reservoir) ecosystem. No significant differences between tides were observed for all variables, except for the water light extinction coefficient (k) values, reflecting higher turbidity during the ebb.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pelagic metabolism of the Douro estuary (Portugal) – Factors controlling primary production

Azevedo

Duarte

Bordalo

2006

Estuarine, Coastal and Shelf Science

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“…The importance of such bottom-up controls on community composition is often assumed for ecosystems; however, owing to the inherent complexity of bacterial communities and the practical difficulty of making comparisons of small-scale phenomena across large spatial scales, such controls are difficult to determine. Additionally, the abiotic factors that influence community dynamics appear to vary among different ecosystems, and among different zones within an ecosystem (Noble et al 2003, Pinhassi et al 2003, Bordalo & Vieira 2005.The composition of bacterioplankton populations is also influenced by the composition of phytoplankton communities. In lakes, estuaries, and the marine environment, bacterial production, function, and community composition change as phytoplankton blooms form, develop, and then collapse (Kirchman et al 1991, Fandino et al 2001, Riemann & Winding 2001.…”

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confidence: 99%

Linking bacterioplankton community structures to environmental state variables and phytoplankton assemblages in two South Carolina salt marsh estuaries

Johnson¹,

Lewitus²,

Fletcher³

2006

Aquat. Microb. Ecol.

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Microorganisms are among the most important organisms to the ecology of salt marsh estuaries; however, fundamental questions regarding their distribution, environmental controls, and interactions with phytoplankton remain unanswered. We used denaturing gradient gel electrophoresis (DGGE) of bacterial rRNA genes and high performance liquid chromatography (HPLC) of phytoplankton photopigments to characterize planktonic communities from the Ashepoo, Combahee, and Edisto (ACE) Basin and North Inlet (NI) estuaries on the South Carolina coast, USA. Multivariate comparisons of the planktonic community profiles revealed that the 2 estuaries supported distinct bacterial communities. Furthermore, bacterial communities in both systems were partitioned into separate particle-associated (PA) and free-living (FL) components. Differences in bacterial populations were also observed along the salinity gradient within each system. Comparisons of water physicochemistry with bacterial profiles indicated significant correlation of PA bacterial community structures with temperature, salinity, organic carbon, total phosphorus, and ammonium, whereas FL communities were affected by nitrate, ammonium, total phosphorus and orthophosphate. PA bacterioplankton community structures were also associated with diatoms, dinoflagellates, haptophytes and cryptophytes, while FL assemblages corresponded to prasinophytes, chlorophytes, and cyanobacteria. Comparisons between estuaries further demonstrated that ACE Basin communities were mostly associated with the same pigments as PA samples, and that NI assemblages correlated with FLassociated phytoplankton, suggesting different trophodynamics of particles in the 2 systems.KEY WORDS: Bacteria · Phytoplankton · Community structure · HPLC · DGGE · Salt marsh estuary Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 45: [129][130][131][132][133][134][135][136][137][138][139][140][141][142][143][144][145] 2006 In some aquatic ecosystems abiotic factors such as riverine input, salinity, temperature, or availability of nutrients have been shown to control the composition of the plankton communities present (Lind & Barcena 2003, Smith & Kemp 2003, Kirchman et al. 2004. In estuarine systems in particular, phytoplankton and bacterioplankton productivity and taxonomic composition have been shown to be sensitive to changes in nutrient concentrations (Noble et al. 1997, Seitzinger & Sanders 1999, Kirchman et al. 2004, Lagus et al. 2004). However, other research has demonstrated that the structure of complex, natural communities as well as relatively simple bacterial assemblages may remain unchanged when exposed to significant shifts in nutrient chemistry (Fernandez et al. 1999, Piceno & Lovell 2000, Lovell et al. 2001, LaPara et al. 2002. The importance of such bottom-up controls on community composition is often assumed for ecosystems; however, owing to the inherent complexity of bacterial communities and the practical difficulty of making comparisons of...

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The influence of dunes on mixing in a migrating salt‐wedge: Fraser River estuary, Canada

Kostaschuk

Best

Villard³

2010

Earth Surf Processes Landf

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Dune bedforms and salt-wedge intrusions are common features in many estuaries with sand beds, and yet little is known about the interactions between the two. Flow visualization with an echosounder and velocity measurements with an acoustic Doppler current profi ler over areas of fl at-bed and sand dunes in the highly-stratifi ed Fraser River estuary, Canada, were used to examine the effect of dunes on interfacial mixing. As the salt-wedge migrates upstream over the fl at-bed, mixing is restricted to the lower portion of the water column. However, as the salt-wedge migrates into the dune fi eld from the fl at bed, there is a dramatic change in the fl ow, and large internal in-phase waves develop over each of the larger dunes, with water from the saltwedge reaching the surface of the estuary. The friction Richardson number shows that bed friction is more important in interfacial mixing over the dunes than over the fl at-bed, and a plot of internal Froude Number versus obstacle (dune) height shows that the salt-wedge fl ow over the dunes is mainly supercritical. Such bedforms can be expected to cause similar effects in interfacial mixing in other estuaries and sediment-laden density currents, and may thus be infl uential in fl uid mixing and sediment transport.

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Spatial variability of phytoplankton, bacteria and viruses in the mesotidal salt wedge Douro Estuary (Portugal)

Cited by 34 publications

References 48 publications

Pelagic metabolism of the Douro estuary (Portugal) – Factors controlling primary production

Pelagic metabolism of the Douro estuary (Portugal) – Factors controlling primary production

Linking bacterioplankton community structures to environmental state variables and phytoplankton assemblages in two South Carolina salt marsh estuaries

The influence of dunes on mixing in a migrating salt‐wedge: Fraser River estuary, Canada

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