Ammonium uptake by seagrass epiphytes: Isolation of the effects of water velocity using an isotope label

Cornelisen, Christopher D.; Thomas, Florence I. M.

doi:10.4319/lo.2002.47.4.1223

Cited by 43 publications

(33 citation statements)

References 24 publications

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“…In current-driven flows, seagrass community uptake rates of dissolved inorganic nitrogen (DIN) are consistent with theory describing mass transfer limited (MTL) exchange (Thomas et al 2000, Cornelisen & Thomas 2002, Thomas & Cornelisen 2003. Under MTL conditions, uptake rates are determined solely by physical properties and interactions like fluid velocity, canopy drag, and surface roughness.…”

Section: Introductionsupporting

confidence: 48%

“…Epiphytes were scraped from the top 10 cm and from the bottom 10 cm of T. testudinum blades using the straight edge of a microscope slide (Cornelisen & Thomas 2002). In cases when the blade length was less than 20 cm, the blade was divided into top and bottom halves.…”

Section: Uptake Sample Collection and Processingmentioning

confidence: 99%

“…As the epibionts scraped from the seagrass blades may have contained varying populations of photosynthetic and non-photosynthetic organisms, rates of DIN uptake by epiphytes were normalized to their nitrogen and chlorophyll content (see Cornelisen & Thomas 2002) to provide uptake rates (ρ) in units of (g N removed) (mg chl a)…”

Section: Uptake Sample Collection and Processingmentioning

confidence: 99%

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Uptake of dissolved inorganic nitrogen by shallow seagrass communities exposed to wave-driven unsteady flow

Weitzman

Aveni-Deforge²,

Koseff³

et al. 2013

Mar. Ecol. Prog. Ser.

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In natural seagrass systems, regular oscillatory motion -like that caused by surface wind-waves -enhances uptake of dissolved inorganic nitrogen (DIN) relative to current-driven, unidirectional flows. A mobile field flume was deployed to measure the uptake of DIN by intact shallow seagrass communities exposed to unidirectional, oscillatory, and combined flows. The flume volume was spiked with 15 N-labeled DIN to measure nutrient uptake rate constants for the entire system (S) and to determine height-specific nutrient uptake rates of seagrass epiphytes (ρ). In oscillatory and combined flows, S depended positively on the water speed, but also inversely on a modified Keulegan-Carpenter number (KC). This ratio compares the wave-orbital excursion distance to canopy element spacing. Experiments characterized by relatively low KC values were associated with significantly higher uptake efficiencies than experiments characterized by high KC values. Uptake efficiencies for high KC conditions were similar to those measured in comparable unidirectional flows. Measured canopy flow attenuation was also found to increase with KC, a result in line with expectations from a parameterized conceptual model. Damping variability alone could not explain the observed oscillatory flow uptake enhancement however, a result that seemingly highlights the role of both element flexural response and unsteady boundary layer mechanics in the exchange process. In all flow conditions, DIN uptake rates of epiphytes harvested from the bottom of the blades (ρ bot ) were lower than those for epiphytes harvested from the upper portion of the blades (ρ top ). While uptake by the top epiphytes exhibited flow dependency, uptake by bottom epiphytes did not.

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Section: Introductionsupporting

confidence: 48%

Section: Uptake Sample Collection and Processingmentioning

confidence: 99%

Section: Uptake Sample Collection and Processingmentioning

confidence: 99%

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Uptake of dissolved inorganic nitrogen by shallow seagrass communities exposed to wave-driven unsteady flow

Weitzman

Aveni-Deforge²,

Koseff³

et al. 2013

Mar. Ecol. Prog. Ser.

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“…This effect of velocity on nutrient uptake has been demonstrated for individual organisms (e.g. Gerard 1982, Hurd et al 1996, Cornelisen & Thomas 2002 and groups of organisms (e.g. , Larned & Atkinson 1997, Thomas & Atkinson 1997).…”

Section: Introductionmentioning

confidence: 99%

Ammonium uptake by seagrass communities: effects of oscillatory versus unidirectional flow

Thomas¹,

Cornelisen²

2003

Mar. Ecol. Prog. Ser.

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Nutrient dynamics of aquatic communities are dependent on the flux of nutrients to organisms within the communities. Flux is dependent on water column concentration and hydrodynamic factors that affect both advection of nutrients through the community and rates of diffusion at the surfaces of organisms. In this study, we measured rates of ammonium uptake for a seagrass community under various hydrodynamic conditions and determined the effects of water velocity and oscillatory flow on uptake rates. Experiments were conducted using a portable flume deployed in natural Thalassia testudinum communities. Uptake rate constants ranged from 9.9 to 25.4 × 10 -5 m s -1 and were ~1.5 times higher in oscillatory flow than in unidirectional flow. Uptake rate constants were positively dependent on both water velocity and turbulent energy in the water column. These results demonstrate the importance of hydrodynamics on biogeochemical cycling in seagrass beds and provide evidence of the efficacy of merging research on hydrodynamics and biogeochemistry in understanding nutrient processes in complex nearshore communities.

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“…Epiphytes also help seagrass in nitrogen fixation [8] [15] and nutrient cycling [16]. [15] (Novak, 1984) and T. testudinum of Florida Bay [22].…”

Section: Introductionmentioning

confidence: 99%

Epiphytic Bacterial Communities in Seagrass Meadows of Oligotrophic Waters of Andaman Sea

Mishra¹,

Mohanraju²

2018

OALib

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The epiphytic microbial communities of seagrass (Cymodocea rotundata and Thalassia testudinum) along with sediments and seawater of the seagrass ecosystem of Andaman Sea were assessed for heterotrophic bacterial communities. Young leaves of C. nodosa and T. testudinum sediments and water samples were collected from two different locations at Burmanala and Havelock island. Young leaves were swabbed and transferred into Alkaline peptone water along with 1 gm of sediments and 1 ml of seawater for initial microbial enrichments, followed by culture of microbes in Salt Yeast Extract Agar. Thiosulphate Citrate Bile Salt agar was used for seagrass leaves, sediments and water for culturing of Vibrio like microbes. The observed colonies were morphologically (colour) identified first and then further identification was done by Gram staining and various biochemical tests. Sediment bacterial count was 10-fold higher than seagrass and water column communities. Morphologically 29% of total bacterial colonies identified were of grey and white colour. T. testudinum bacterial epiphytes were 2-fold higher than C. rotundata communities. Gram negative bacterial isolates of Pseudomonas, Vibrios and Aeromonas dominated the bacterial colonies than gram positive bacteria of Bacillus and Micrococcus. Vibrios were only observed on seagrass leaves. Seagrass harboured more gram positive bacterial colonies than gram negative, which were dominated in the sediments of seagrass ecosystem. The bacterial communities of landward site of Burmanala and Havelock were similar whereas 2-fold higher communities were observed at the seaward site of Havelock site on T. testudinum. Seagrass ecosystem bacterial epiphytic communities are diverse in oligotrophic waters.

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Ammonium uptake by seagrass epiphytes: Isolation of the effects of water velocity using an isotope label

Cited by 43 publications

References 24 publications

Uptake of dissolved inorganic nitrogen by shallow seagrass communities exposed to wave-driven unsteady flow

Uptake of dissolved inorganic nitrogen by shallow seagrass communities exposed to wave-driven unsteady flow

Ammonium uptake by seagrass communities: effects of oscillatory versus unidirectional flow

Epiphytic Bacterial Communities in Seagrass Meadows of Oligotrophic Waters of Andaman Sea

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