Short-term effect of oxic to anoxic transition on benthic microbial activity and solute fluxes in organic-rich phytotreatment ponds

Benthic infauna in marine sediments have well-documented effects on biogeochemical cycling, from individual to ecosystem scales, including stimulation of nitrification and nitrogen removal via denitrification. However, the effects of burrowing depth and irrigation patterns on nitrogen cycling have not been as well described. Here we examined the effects of lugworm behavior on sediment nitrogen cycling using a reaction-transport model parameterized with literature and laboratory data. Feeding pocket depth and pumping characteristics (flow rate and pattern) were varied, and rates of nitrification, denitrification, and benthic exchange fluxes were computed. As expected, more intense burrow irrigation stimulated denitrification and coupled nitrification−denitrification. At high pumping rates and low sediment oxygen consumption rates (~10 −6 mol m −3 s −1 ), simulation results showed a decrease in rates of nitrification and denitrification with decreasing burrow depth due to incomplete consumption of injected oxidants. Model results also suggest that discontinuous irrigation leads to temporal variability in sediment nitrogen cycling, but that the time-averaged rates do not depend on the irrigation pattern. We identify (1) the poorly constrained chemical composition of lumen fluid injected into sediments and (2) the response of microbial activity/distribution to oscillating redox conditions as critical knowledge gaps affecting estimates of sediment nitrogen removal.

show abstract

“…4). This is precisely the pattern seen by Bartoli et al (2000) in a microcosm simulation of the initial stages of such a recolonization event.…”

Section: Benthic Context and Controls On Nitrogen Cyclingsupporting

confidence: 66%

Modeling lugworm irrigation behavior effects on sediment nitrogen cycling

Dornhoffer¹,

Waldbusser²,

Meile³

2015

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…To our knowledge there are no published informations on SRP microprofiles and we thus cannot discuss whether the resolution of our profiles leads to wrong estimates of true phosphorous fluxes. Furthermore, bioturbation activities by large macrofauna, not considered in the present study, can strongly enhance, up to a factor 4, the regeneration of nutrients (Glud et al, 2003;Stief and De Beer, 2006;Bartoli et al, 2009). As a consequence, theoretical, diffusive fluxes calculated in bioturbated sediments can largely underestimate fluxes measured with intact cores incubation.…”

Section: Discussionmentioning

confidence: 68%

Sediment-water oxygen, ammonium and soluble reactive phosphorus fluxes in a turbid freshwater estuary (Curonian lagoon, Lithuania): evidences of benthic microalgal activity

et al. 2012

View full text Add to dashboard Cite

Seasonal measurements of total and diffusive benthic fluxes were performed during the ice-free period in the Curonian Lagoon (Lithuania). This mostly freshwater hypertrophic basin exhibits wide seasonal variations of water temperature (1-22°C) and inorganic nitrogen availability and it is subjected to dramatic blooms of diatoms and cyanobacteria (>100 mg chl a L -1 ). In this shallow lagoon, nutrient exchanges at the sediment-water interface and the regulating factors have been poorly explored. Overall aim of the present work is to demonstrate that the activity of benthic microalgae, generally neglected in turbid systems, can be a relevant regulator of sedimentary processes. To this purpose, light and dark fluxes of oxygen, ammonium and soluble reactive phosphorus were measured seasonally by intact core laboratory incubation and diffusive fluxes were calculated from sediment profiles. We investigated sandy sediments that were collected from the central area lagoon, that is representative of the most of the shallower lagoon area.Oxygen and ammonium fluxes were significantly different under light and dark incubations, suggesting an active role of benthic microalgae at the sediment-water interface. In the light net oxygen production was measured in three out of four samplings, with July as only exception, and ammonium was retained within sediments. In the dark sediment respiration displayed a temperature-dependent pattern while ammonium efflux increased from March to October. Fluxes of reactive phosphorus varied significantly with sampling seasons but were less affected by the incubation condition. Diffusive fluxes peaked in July, where highest concentration gradients at the interface and theoretical efflux of ammonium and reactive phosphorous were calculated. The marked differences between diffusive and total nutrient fluxes are probably due to photosynthetic activity by benthic microalgae, and thus oxygen production, enhancement of aerobic processes and net solute uptake at the sediment-water interface. Our findings support the hypothesis that even in highly turbid systems benthic microalgae can have a relevant role as filters for regenerated nutrients and as regulators of benthic processes.

show abstract

Eutrophication of the Mediterranean Sea: a watershed—cascading aquatic filter approach

Viaroli

Nizzoli

Pinardi

et al. 2014

Rend. Fis. Acc. Lincei

View full text Add to dashboard Cite

A general review of spider burrows and history of their research in eighteenth to nineteenth centuries are provided on the basis of the literature, which is dispersed and almost forgotten by majority of ichnologists. Moreover, burrows of the wolf spider Trochosa hispanica Simon, 1870 from a mountain meadow in Albania are presented. They are composed of an almost straight through gently curved to slightly winding vertical shafts (8.2-17.2 mm in diameter) with a basal, oval chamber, which is 14.5-30.6 mm wide. Above the ground level, some of them show a low, agglutinated chimney a cone composed of soil granules. The burrows are 83-235 mm long. They are comparable with the trace fossil Macanopsis Macsotay, 1967. Other spider burrows can form a simple shaft, which may be ascribed to the ichnogenus Skolithos Haldeman, 1840, or a shaft with the side oblique branches, which is is similar to the ichnogenus Psilonichnus Fürsich, 1981. Many spider burrows show one or more chambers. Their outlet may be closed with a trapdoor or show a chimney sticking above the ground. They may show scratch traces running parallel to the burrow. The burrows are domiciles in which spiders spend a part of, or even the whole life. They protect spiders against harsh environmental conditions, foremost against too low or to high temperature, sheet floods, or predators. Moreover, they can be also a place for copulation, oviposition, parental care, placement of cocoons, or shedding the exuvia. Burrowing spider are more common in in warmer climatic zones, in open space, above the water ground level, and less common in flooded. So far, very few examples of fossil spider burrows are recognised, mostly in Cenozoic sediments, even if spiders are known since the Carboniferous.

show abstract

Short-term effect of oxic to anoxic transition on benthic microbial activity and solute fluxes in organic-rich phytotreatment ponds

Cited by 16 publications

References 59 publications

Modeling lugworm irrigation behavior effects on sediment nitrogen cycling

Modeling lugworm irrigation behavior effects on sediment nitrogen cycling

Sediment-water oxygen, ammonium and soluble reactive phosphorus fluxes in a turbid freshwater estuary (Curonian lagoon, Lithuania): evidences of benthic microalgal activity

Eutrophication of the Mediterranean Sea: a watershed—cascading aquatic filter approach

Contact Info

Product

Resources

About