Seasonal shift in net ecosystem production in a tropical estuary

Ram, Anirudh; Nair, Shanta; Chandramohan, D.

doi:10.4319/lo.2003.48.4.1601

Cited by 108 publications

(54 citation statements)

References 36 publications

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“…the bacterial carbon demand is met either by the exogenous organic carbon or DOC reservoir source, in addition to those derived from local contemporaneous phytoplankton. This shift in the trophic status corroborates with our earlier findings using the alternative approach of net oxygen and CO 2 gas flux across air-sea interface in this estuarine system [40]. Significant relationship (p < 0.01) between BP and PP in the dry pre-monsoon season suggested PP to be the dominant source of carbon for bacterioplankton growth.…”

Section: Discussionsupporting

confidence: 91%

“…BP and BR. A significant relationship between BGE and BP, (not BR) at the estuaries, as seen in the present study, has been reported previously [40,42]. Across a range of aquatic ecosystems, BP was consistently shown to be more variable than BR [eg.…”

Section: Discussionsupporting

confidence: 85%

“…In our study we tried to reduce the incubation time as much as possible to detect the significant decrease in dissolved oxygen in the samples, in order to minimize the bias in the BGE determination. The linear decrease in oxygen during incubation as observed in our previous study [40] and the present study suggests that size-fractionation artifacts were not substantial. The Winkler technique has been most commonly used technique to estimate BR.…”

Section: Bacterial Productivity Respiration and Growth Efficiencysupporting

confidence: 88%

“…Filtration was done under a low differential pressure (< 50 mm Hg) to avoid disruption of fragile cells. [40]. In our study we tried to reduce the incubation time as much as possible to detect the significant decrease in dissolved oxygen in the samples, in order to minimize the bias in the BGE determination.…”

Section: Bacterial Productivity Respiration and Growth Efficiencymentioning

confidence: 99%

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Bacterial Growth Efficiency in a Tropical Estuary: Seasonal Variability Subsidized by Allochthonous Carbon

2007

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Bacterial growth efficiency (BGE) is a key factor in understanding bacterial influence on carbon flow in aquatic ecosystems. We report intra annual variability in BGE, and bacteria mediated carbon flow in the tropical Mandovi and Zuari estuaries (southwest India) and the adjoining coastal waters (Arabian Sea). BGE ranged from 3 to 61% and showed clear temporal variability with significantly (ANOVA, p < 0.01) higher values in the estuaries (mean, 28 ± 14%) than coastal waters (mean 12 ± 6%). The greater variability of BGE in the estuaries than coastal waters suggest some systematic response to nutrient composition and the variability of dissolved organic matter pools, as BGE was governed by bacterial secondary production (BP). Monsoonal rains and its accompanied changes brought significant variability in BGE and bacterial productivity to primary productivity (BP/PP) ratio when compared to non-monsoon seasons in the estuaries and coastal waters. High BP/PP ratio (> 1) together with high carbon flux through bacteria (> 100% of primary productivity) in the estuarine and coastal waters suggests that bacterioplankton consumed dissolved organic carbon in excess of the amount produced in situ by phytoplankton of this region, which led to the mismatch between primary production of carbon and amount of carbon consumed by bacteria. Despite the two systems being subsidized by allochthonous inputs, the low BGE in the coastal waters may be due to the nature and time interval in the supply of allochthonous carbon.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 85%

Section: Bacterial Productivity Respiration and Growth Efficiencysupporting

confidence: 88%

Section: Bacterial Productivity Respiration and Growth Efficiencymentioning

confidence: 99%

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Bacterial Growth Efficiency in a Tropical Estuary: Seasonal Variability Subsidized by Allochthonous Carbon

2007

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“…Seasonal shifts from auto-to heterotrophy according to river flow variations have also been reported. For example, heterotrophy occurs during monsoon periods in tropical estuaries, when increased allochthonous organic input leads to enhanced respiration (Ram et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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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Distribution and sources of particulate organic matter in the Indian monsoonal estuaries during monsoon

et al. 2014

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The distribution and sources of particulate organic carbon (POC) and nitrogen (PN) in 27 Indian estuaries were examined during the monsoon using the content and isotopic composition of carbon and nitrogen. Higher phytoplankton biomass was noticed in estuaries with deeper photic zone than other estuaries receiving higher suspended matter. The δ 13 C POC and δ 15 N PN data suggest that relatively higher δ 13 C POC (À27.9 to À22.6‰) and lower δ 15 N PN (0.7 to 5.8‰) were noticed in the estuaries located in the northern India, north of 16°N, and lower δ 13 C POC (À31.4 to À28.2‰) and higher δ 15 N PN (5 to 10.3‰) in the estuaries located in the southern India. This is associated with higher Chl a in the northern than southern estuaries suggesting that in situ production contributed significantly to the POC pool in the former, whereas terrestrial sources are important in the latter estuaries. The spatial distribution pattern of δ 15 N PN is consistent with fertilizer consumption in the Indian subcontinent, which is twice as much in the northern India as in the south whereas δ 13 C POC suggests that in situ production is a dominant source in the southern and terrestrial sources are important in the northern estuaries. Based on the Stable Isotope Analysis in R model, 40-90% (70-90%) of organic matter is contributed by C 3 plants (freshwater algae) in the estuaries located in the northern (southern) India.

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Seasonal shift in net ecosystem production in a tropical estuary

Cited by 108 publications

References 36 publications

Bacterial Growth Efficiency in a Tropical Estuary: Seasonal Variability Subsidized by Allochthonous Carbon

Bacterial Growth Efficiency in a Tropical Estuary: Seasonal Variability Subsidized by Allochthonous Carbon

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

Distribution and sources of particulate organic matter in the Indian monsoonal estuaries during monsoon

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