Modelling bio-irrigation rates in the sediments of Port Phillip Bay

Berelson, W.; Townsend, Tim; Heggie, David T.; Ford, Phillip W.; Longmore, Andrew R.; Skyring, G. W.; Kilgore, Tammy E.; Nicholson, G.

doi:10.1071/mf98076

Cited by 15 publications

(7 citation statements)

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“…The model accounted for loss of a tracer by both adsorption (assumed to be negligible) and bio-irrigation (Berelson et al, 1999;Townsend, 1998). The observed loss of Cs tracer from within the chambers (when normalised to initial Cs concentration) at the three sites was always greater than that predicted by diffusion alone (Fig.…”

Section: Biophysical Processes In Sedimentsmentioning

confidence: 99%

“…The diffusive loss of tracer ions from the chamber to the sediments was computed from a finite difference model described by Townsend (1998) and Berelson et al (1999). The model accounted for loss of a tracer by both adsorption (assumed to be negligible) and bio-irrigation (Berelson et al, 1999;Townsend, 1998).…”

Section: Biophysical Processes In Sedimentsmentioning

confidence: 99%

“…The fraction of N-input denitrified has been shown to increase with increasing residence times (Nixon et al, 1996;Nowicki et al, 1997). Port Phillip Bay Australia and the Myall Lakes have long residence times (*400 days) and 'high' denitrification efficiencies in PPB sediments maintained 'good' water quality and ecosystem conditions (Harris et al, 1996;Berelson et al, 1998Berelson et al, , 1999Heggie et al, 1999a, b).…”

Section: Introductionmentioning

confidence: 96%

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Biogeochemical processes at the sediment–water interface, Bombah Broadwater, Myall Lakes

et al. 2008

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Myall Lakes has experienced algal blooms in recent years which threaten water quality. Biomarkers, benthic fluxes measured with chambers, and pore water metabolites were used to identify the nature and reactivity of organic matter (OM) in the sediments of Bombah Broadwater (BB), and the processes controlling sediment-nutrient release into the overlying waters. The OM in the sediments was principally from algal sources although terrestrial OM was found near the Myall River. Terrestrial faecal matter was identified in muddy sediments and was probably sourced via runoff from farm lands. The reactive OM which released nutrients into the overlying waters was from diatoms, dinoflagellates and probably cyanobacteria. Microcystis filaments were observed in surface sediments. OM degradation rates varied between 5.3 and 47.1 mmol m -2 day -1 (64-565 mg m -2 day -1 ), were highest in the muddy sediments and sulphate reduction rates accounted for 20-40% of the OM degraded. Diatoms, being heavy sink rapidly, and are an important vector to transport catchment N and P to sites of denitrification and P-trapping in the sediments. Denitrification rates (mean *4 mmol N m -2 day -1 ), up to 7 mmol N m -2 day -1 (105 mg N m -2 day -1 ) were measured, and denitrification efficiencies were highest (mean = 86 ± 4%) in the sandy sediments (*20% of the area of BB), but lower in the muddy sediments (mean = 63 ± 15%). These differences probably result from higher OM loads and anaerobic respiration in muddy sediments. Most DIP ([70%) from OM degradation was not released into overlying waters but remained trapped in surface sediments. Biophysical (advective) processes were responsible for the measured metabolite (O 2 , CO 2 , DSi, DIN and DIP) fluxes across the sediment-water interface.

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Section: Biophysical Processes In Sedimentsmentioning

confidence: 99%

Section: Biophysical Processes In Sedimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Biogeochemical processes at the sediment–water interface, Bombah Broadwater, Myall Lakes

et al. 2008

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“…The chamber lids were sealed remotely at sundown on Day 1, and following lid closure 20 ml of 3% caesium chloride (CsCl) was injected into each chamber to give an estimated initial start concentration of approximately 35 ppm. CsCl was used as a water movement tracer after Berelson et al (1999), and sediment irrigation was calculated by assuming that dilution was caused by the diffusion and active bio-irrigation of CsCl-contaminated water into the sediments, to be replaced by uncontaminated water from the interstitial reservoir. Samples were drawn from each chamber by a remote sample tube ( Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Cs is adsorbed onto sediment particles (Townsend 1998), and the determination of sediment exchange and irrigation rates using Cs dilution over time may be underestimated due to adsorption onto resuspended particles and the sediment surface. The determination of standard correction coefficients is problematic as adsorption rates vary with differing sediment types (Townsend 1998, Berelson et al 1999. Since the sediment type was the same in both incubations, the adsorption rate is assumed to be similar in both incubations.…”

Section: Tracer (Caesium Chloride) Behaviourmentioning

confidence: 99%

Effect of natural populations of burrowing thalassinidean shrimp on sediment irrigation, benthic metabolism, nutrient fluxes and denitrification

Webb¹,

Eyre²

2004

Mar. Ecol. Prog. Ser.

144

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The aim of this study was to determine the effect of burrowing by natural populations of Trypaea australiensis on benthic metabolism, nutrient flux, denitrification and irrigation rates using in situ benthic chambers and exclusion nets to minimise disturbance and associated artefacts. The burrows of T. australiensis enhanced total sediment porewater exchange rates 5-fold compared to uninhabited sediments. Calculated single-burrow flow rates were < 0.456 l h -1, and active burrow irrigation appeared to be linked to tidal movement; as such, ex situ studies (i.e. mesocosm or laboratory incubations) may underestimate burrow irrigation rates. The presence of T. australiensis increased sediment oxygen demand by 81% as compared to unoccupied sediments. Approximately 15% of this additional consumption was used by T. australiensis for respiration, with the remaining 85% consumed within the burrows by oxidation reactions and microbial respiration. The proportion of smaller sediment particles, porosity and organic matter content was increased in the presence of T. australiensis, and sediment surface chl a concentrations were ca. 50% lower than uninhabited sediments. Net denitrification rates were 4 times greater in the presence of active T. australiensis burrows and at densities of 22 burrows m -2 were responsible for approximately 76% of total denitrification in the study site sediments. NH 4 + efflux was higher in the inhabited sediments and NO 3 -and NO 2 -effluxes were lower, suggesting that increased NH 4 + mineralisation may have enhanced denitrification via the close coupling of nitrification-denitrification in the inhabited sediments. As such, T. australiensis appears to contribute significantly to net sediment N 2 efflux in lower subtropical estuarine environments.

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Diagenetic stoichiometry and benthic nutrient fluxes at the sediment–water interface of Lake Illawarra, Australia

Morrison

West

et al. 2005

Hydrobiologia

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Benthic flux measurements of O 2 , TCO 2 and inorganic nutrients were made at three stations (seagrass beds, shallow bare sand and deep mud) in Lake Illawarra (Australia) to compare the characteristics of diagenesis and benthic biogeochemical processes for different primary producers (seagrass or microphytobenthos, (MPB)) and/or sediment types (sand or mud).Seagrass beds exhibited the highest gross primary productivity while the lowest rates occurred at the deep mud station. At the shallow bare sand station only, the gross primary production (GPP) and respiration (R) were balanced, while at the other two stations, R exceeded GPP by as much as 2 fold, indicating more organic carbon was decomposed than produced at the time of sampling. In general, nutrient fluxes displayed typical diurnal variation.Organic carbon oxidation scenarios, evaluated by either calcium carbonate dissolution or sulfate reduction models, indicated that both models can represent organic matter mineralization. The difference of estimated total carbon oxidized in this lake using the two models was small, ranging from 0.2% at deep mud station to maximum of 21% at seagrass station. In addition, N 2 flux rates (net denitrification), estimated using carbon and nitrogen stoichiometry, were of similar magnitude as the rates estimated using LOICZ budget modeling or measured using the N 2 /Ar technique.Finally, a comparison of calculated diffusive fluxes and measured fluxes using incubation cores indicated that the results were of similar magnitude at the deep mud station, but the incubation cores fluxes were much higher than the calculated diffusive fluxes at the other two stations. This may have been caused by bioturbation or bioirrigation.

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Modelling bio-irrigation rates in the sediments of Port Phillip Bay

Cited by 15 publications

References 0 publications

Biogeochemical processes at the sediment–water interface, Bombah Broadwater, Myall Lakes

Biogeochemical processes at the sediment–water interface, Bombah Broadwater, Myall Lakes

Effect of natural populations of burrowing thalassinidean shrimp on sediment irrigation, benthic metabolism, nutrient fluxes and denitrification

Diagenetic stoichiometry and benthic nutrient fluxes at the sediment–water interface of Lake Illawarra, Australia

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