Small-scale temporal and spatial variability in the erosion threshold and properties of cohesive intertidal sediments

Tolhurst, T.J.; Defew, Emma C.; Brouwer, J.F.C. de; Wolfstein, K.; Stal, Lucas J.; Paterson, David M.

doi:10.1016/j.csr.2005.11.007

Cited by 73 publications

(44 citation statements)

References 40 publications

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“…The mean values for all treatments on day 15 were consistently large (compare days 0 and 4 with day 15 in Fig. 1c); these values are consistent, however, with results obtained from other estuaries (Tolhurst et al, 2006a) and at other times in these sites .…”

Section: Effects On Sediments That Were Physically Disturbedsupporting

confidence: 58%

“…burrowing and feeding, can significantly alter properties of sediments, such as erodibility, porosity, permeability and grain size (Meadows and Tait, 1989;Meadows et al, 1990). Erosion on mudflats is mediated by the interplay between biological and physical processes (de Brouwer et al, 2000;Defew et al, 2002;Tolhurst et al, 2006b) and can be significantly altered by fauna (Austen et al, 1999;Widdows et al, 2000;Andersen et al, 2002) and flora (Friend et al, 2003;Tolhurst et al, 2006a). Often, an organism can have multiple synergistic or antagonistic influences on properties and processes that may vary temporally and/or spatially (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Technical Note: The effects of five different defaunation methods on biogeochemical properties of intertidal sediment

et al. 2012

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Abstract. Various methods have been used to remove organisms from sediments to investigate structure and function of faunal assemblages in intertidal habitats. Nevertheless, little is known about how these treatments affect properties of the sediments themselves, although changing these properties may cause changes in the assemblages, independently of other hypotheses being tested. This study assesses the efficacy of defaunation and effect on selected biogeochemical properties of five different methods of defaunating soft muddy sediments in an estuary. The methods were removal and freezing of sediment, removal and oven-heating, freezing in situ with liquid N 2 , spraying with formalin and spraying with hydrogen peroxide. The first four of these methods have been used in previous studies, whilst the fifth was considered to be a potentially useful defaunator because it does not leave toxic residues. The first two methods required sediment to be brought back to the lab, disrupting the natural structure of the sediment; the last three were done in situ, with much less disturbance.Variables measured to assess effects of the treatments on the sediment were amount of water, grain size, total carbohydrate, suspension index (relative erosion rate), erosion threshold, chlorophyll a and b, colloidal carbohydrate, F o (minimal fluorescence) and F v / F m (photosynthetic yield). There were no significant effects of any treatment on the first four variables. For the others, effects of defaunation varied from treatment to treatment and with time after treatment. Generally, the greatest disturbance was to the microphytobenthos (MPB, measured by chlorophyll and fluorescence) and related variables. For most treatments, recovery was rapid, but the effects of formalin and H 2 O 2 persisted for a few days. Effects on physical properties of the sediment were mostly minor and insignificant. Removal and freezing or heating, however, caused major changes to the sediments because of the disturbances involved. Choosing the appropriate method of defaunation is very important if interpretations are not to be confounded between the effects of defaunation per se and any effects of changes to other biota (such as microphytobenthos) and/or the properties of sediments caused by the method used to defaunate experimental areas.

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Section: Effects On Sediments That Were Physically Disturbedsupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Technical Note: The effects of five different defaunation methods on biogeochemical properties of intertidal sediment

et al. 2012

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“…The EPS produced within diatom biofilms allow them to form mat-like structures on the surface of sediment, which increase erosion thresholds and stabilize sediment (Yallop et al 1994, Sutherland et al 1998). Thus, heterogeneity in diatom distributions due to deposit feeding contributes to EPS patchiness; consequently, erosion is more likely to occur (Lanuru 2004, Tolhurst et al 2006.…”

Section: Discussionmentioning

confidence: 99%

Interacting effects of deposit feeding and tidal resuspension on benthic microalgal community structure and spatial patterns

Plante¹,

Frank²,

Roth³

2011

Mar. Ecol. Prog. Ser.

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Benthic microalgae (BMA) are important primary producers constituting an essential component of nearshore food webs. BMA also release extracellular polymeric secretions that stabilize sediments. Primary objectives of our research were to assess the separate and interactive effects of biotic and abiotic disturbances on structure and spatial patterns of microalgal communities in shallow-water sediments. Using field comparative studies, we characterized the effects of 2 prominent types of disturbance: macroinvertebrate ingestion and tidal resuspension. BMA biomass and composition in fecal materials from the enteropneust Balanoglossus aurantiacus and sediments were followed through time using fluorometry and molecular techniques (PCR-DGGE analysis of 18S rDNA and sequencing). We also examined the effects of disturbance on spatial patterns of BMA biomass, diversity, and composition over the larger sedimentary landscape using correlative studies. Deposit-feeder ingestion was found to significantly reduce BMA biomass and alter BMA composition, although qualitative changes were comparatively less remarkable. A significant difference was also found between average biomass before and after tidal immersion. Spatial autocorrelation revealed heterogeneity in BMA distribution during low tide, and that this spatial patterning correlated with B. aurantiacus fecal coils. Samples taken after tidal immersion showed no patchiness, nor was there a correlation between BMA biomass and pre-immersion fecal cover. In intertidal sediments, the qualitative and quantitative impacts of deposit feeding, and the resulting landscape-scale patchiness, appear to be short-lived due to erasure by frequent tidal resuspension.

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“…The carbohydrates exuded by the MPB, including EPS, are utilized by other organisms in the ecosystem, such as bacteria and animals (Middelburg et al 2000, Underwood & Paterson 2003. EPS also affects the biostabilization of sediments (Holland et al 1974), although the relationship between sediment EPS and the erodibility of sediments is complex (Tolhurst et al 2006).Protocols to extract and measure EPS and other carbohydrate fractions from lyophilized sediments have become well established over the last decade (Underwood & Paterson 2003). These methods are simple, and therefore a large number of samples can be processed relatively quickly and at low cost, which is advantageous when working in patchy environments such as coastal sediments.…”

mentioning

confidence: 99%

Measurement of acid polysaccharides (APS) associated with microphytobenthos in salt marsh sediments

Thornton¹,

Visser²

2009

Aquat. Microb. Ecol.

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Microphytobenthos (MPB) are an important component of shallow-water habitats where there is sufficient light to support benthic photosynthesis. Production of extracellular polymeric substances (EPS) is characteristic of the MPB, and acid polysaccharides (APS) are a major component of these EPS. A simple technique was developed to extract and measure APS concentrations in sediments. Water-extractable APS (wAPS) were extracted with ultra high purity water from lyophilized sediments. After centrifuging to remove the sediment, wAPS in the supernatant was precipitated with alcian blue, a cationic dye. The APS-alcian blue precipitate was removed by filtration. The remaining alcian blue in solution was determined spectrophotometrically and was inversely proportional to the concentration of wAPS in the sediment. Chlorophyll (chl) a, carbohydrate fractions, and wAPS were measured in sediments from 5 contrasting sites in a microtidal salt marsh in the subtropics. wAPS concentrations, expressed as gum xanthan equivalents, ranged from 152 to 6268 mg m -2 in the upper 5 mm of sediment. The biomass (determined as chl a) of MPB at all sites was highest in the winter compared to the summer. There was a significant correlation (r = 0.675, p < 0.001, n = 107) between sediment wAPS and chl a concentrations. The ratio of wAPS to salineextractable EPS (sEPS) was significantly higher in summer compared to winter, indicating a seasonal change in the composition of EPS. These data show that APS are a significant and variable component of the EPS pool in salt marsh sediments. KEY WORDS: Exopolymers · EPS · Microphytobenthos · Colloidal carbohydrate · Alcian blue · Subtropics · Gulf of Mexico Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 54: [185][186][187][188][189][190][191][192][193][194][195][196][197][198] 2009 sion feeders, as a substantial proportion of the MPB is regularly re-suspended in many coastal systems (De Jonge & Van Beusekom 1992, Guarini et al. 2004. Middelburg et al. (2000) used a pulse-chase 13 C tracer approach and found that carbon was rapidly transferred (within 1 h) from MPB to bacteria and nematodes within the sediment at a site that was dominated by diatoms. Middelburg et al. (2000) concluded that MPB have a 'central role' in 'moderating carbon flow in coastal sediments. ' A significant proportion of the carbon fixed by the MPB during photosynthesis is exuded into the surrounding environment, mainly as carbohydrates (Smith & Underwood 1998, De Brouwer et al. 2002, Bellinger et al. 2005. These carbohydrates are in the form of extracellular polymeric substances (EPS) and low molecular weight fractions. The terms 'extracellular polymeric substances,' 'exopolymeric substances,' and 'exopolymers' are used interchangeably in the literature and are all abbreviated to EPS. There is considerable interest in the biogeochemistry of EPS in marine ecosystems, both in the water column and in sediments. Verdugo et al. (2004) estimated that there are 70 Pg of ca...

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Small-scale temporal and spatial variability in the erosion threshold and properties of cohesive intertidal sediments

Cited by 73 publications

References 40 publications

Technical Note: The effects of five different defaunation methods on biogeochemical properties of intertidal sediment

Technical Note: The effects of five different defaunation methods on biogeochemical properties of intertidal sediment

Interacting effects of deposit feeding and tidal resuspension on benthic microalgal community structure and spatial patterns

Measurement of acid polysaccharides (APS) associated with microphytobenthos in salt marsh sediments

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