Carbohydrate secretion by phototrophic communities in tidal sediments

Winder, Ben de; Staats, N.; Stal, Lucas J.; Paterson, David M.

doi:10.1016/s1385-1101(99)00021-0

Cited by 99 publications

(69 citation statements)

References 35 publications

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“…7) was typically higher in mat sediments, as measured by an in situ resistivity profiler device (Wheatcroft in press). Other studies (de Winder and Stal 1997;Noffke et al 2001) found that the presence of microbial mats was associated with an increased porosity of sediments, extending down to ϳ10 mm depth, a conclusion similar to our own study (Fig. 7).…”

Section: Discussionsupporting

confidence: 91%

“…EPS are important structuring agents of microbial mats and many sediment systems (Underwood et al 1995;de Winder et al 1999) and may contribute to the physical stability of mat area sediments. EPS abundance in surface (0-5 mm depth) sediments varied dramatically between mat and no-mat areas within a site and between sites and was closely associated with the presence of mat-forming photosynthetic cells.…”

Section: Discussionmentioning

confidence: 99%

“…Earlier work by Amos et al (1996) and Sutherland (1996) documented changes in the bulk density of surface (i.e., top 1.5 mm) sediments, relative to deeper sediments. De Winder and Stal (1997), using resistivity measurements, showed that there was increased porosity in the surface 500 m of sediment associated with mats. With the application of low-temperature scanning electron microscopy the fine-scale features of sediments, while in a hydrated state, could be examined.…”

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confidence: 99%

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Sediment properties influencing upwelling spectral reflectance signatures: The “biofilm gel effect”

Decho

Kawaguchi

Allison

et al. 2003

Limnology & Oceanography

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Microbial communities often produce copious films of extracellular polymeric secretions (EPS) that may interact with sediments to influence spectral reflectance signatures of shallow marine sediments. We examined EPS associated with microbial mats to determine their potential effects on sediment reflectance properties. Distinct changes in spectral reflectance signatures of carbonate sediments from the Bahamas were observed among several sediment sites, which were specifically chosen for their presence of microbial mats and adjacent nonmat sediments. The presence of mats greatly reduced sediment reflectance signatures by ϳ10%-20%, compared with adjacent nonmat areas having similar sediment characteristics. Decreases in reflectance near 444 and 678 nm could be attributed primarily to absorbance by photopigments. However, additional nonspecific decreases in reflectance occurred across a wide spectral range (400-750 nm). Experimental manipulations determined that nonspecific reflectance decreases were due to EPS that are produced by biofilm-associated microorganisms of the mats. Microbial EPS, isolated from natural mat sediments exhibited small but nonspecific absorbances across a broad spectral range. When EPS was in relatively high concentrations, as in microbial mats, there was a ''biofilm gel effect'' on sediment reflectance properties. The effect was twofold. First, it increased the relative spacing of sediment grains, a process that permitted light to penetrate deeper into sediments. Second, it resulted in a more efficient capture of photons because of the change in refractive index of EPS gel itself relative to seawater. The relatively translucent EPS of biofilms, therefore, influenced the magnitude of reflectance across a broad spectral range in marine sediments. Downwelling light, on interaction with carbonate sediments, produces variable upwelling reflectance and scatter- AcknowledgmentsWe thank the staff and scientists of the Caribbean Marine Research Center at Lee Stocking Island, Bahamas, for use of their facilities and for support in carrying out field work. We thank Lisa Drake (Old Dominion University) for help in collecting samples. Finally, we acknowledge the very helpful comments of anonymous reviewers who greatly improved the quality of the manuscript.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Sediment properties influencing upwelling spectral reflectance signatures: The “biofilm gel effect”

Decho

Kawaguchi

Allison

et al. 2003

Limnology & Oceanography

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“…The dominance of cyanobacteria in the epibenthic mats of Puerto Rosales, and in particular the species Microcoleus chthonoplastes, which has many trichomes threaded into a spiral arrangement resulting in a mesh of interweaving cyanobacterial filaments, has been pointed to be indicative of a well-developed microbial mat [31]. The architecture of cyanobacteria filaments proper, and the secretion of EPS interplay and they generate a more efficient entanglement of sediment grains than in a diatom biofilm [32]. This, in turn translates into an established critical biomass of cyanobacteria which does not present biomass fluctuations as marked as those of a diatom biofilm.…”

Section: Discussionmentioning

confidence: 99%

Interaction between Estuarine Microphytobenthos and Physical Forcings: The Role of Atmospheric and Sedimentary Factors

Pan¹,

Bournod²,

Cuadrado³

et al. 2013

IJG

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The goal of this study was to analyze microbial mats and biofilms from the lower supratidal area of the Bahía Blanca estuary (Argentina), and explore their relationship with sediments and other physical forcings. Thirteen monthly sediment samples (uppermost 10 mm) were taken and their composition and abundance in microorganisms was determined by microscopy. Physical parameters (solar radiation and sediment temperature at −5 cm) were recorded with a frequency of 5 minutes by a coastal environmental monitoring station. Additionally, sediment grain size and moisture content were determined for distinct layers in the uppermost 20 mm, and the rate of inundation of the supratidal area was estimated from tidal gauge measurements. There were significant seasonal differences in the biomass of the microphytobenthic groups considered (filamentous cyanobacteria and epipelic diatoms), with the former consistently making up >70% of the total biomass. The relationships between microphytobenthos and sediment temperature and solar radiation fitted to linear regressions, and consistently showed an inverse relationship between microphytobenthic abundance and either one of the physical parameters. The granulometric analysis revealed a unimodal composition of muddy sediments, which were vertically and spatially homogeneous; additionally, there were significant seasonal differences in water content loss with drying conditions prevailing in the summer. Several Microbially-Induced Sedimentary Structures (MISS) were identified in the supratidal zone such as shrinkage cracks, erosional pockets, gas domes, photosynthetic domes, mat chips and sieve-like surfaces. In contrast to studies from analogous environments in the Northern Hemisphere, we found reduced microphytobenthic biomass in summer, which were explained by increased evaporation/desiccation rates as a consequence of increased radiation, despite frequent tidal inundation. In conclusion, the observed density shifts in the benthic microbial communities are attributable to physical forcings dependent upon seasonal variations in interplaying factors such as sediment temperature, solar radiation and tidal inundation.

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“…M. chthonoplastes has a variety of physiological adaptations to drought stress: the production of UV-protective substances (Garcia-Pichel & Castenholz 1991), compatible solutes (Karsten 1996), capsular exopolymeric substances (De Winder et al 1999), and a higher competitive success at high temperature relative to diatoms (Waterman et al 1999) are some examples. In addition, the very low abundance of meio-and macrofauna in the lagoon fringe likely contributed to the preservation of the compact mat structure.…”

Section: Types Of Microbenthic Communities and Spatial Distributionsmentioning

confidence: 99%

Microbenthos in a hypersaline tidal lagoon: factors affecting microhabitat, community structure and mass exchange at the sediment-water interface

García-de-Lomas

Corzo²,

Garcia³

et al. 2005

Aquat. Microb. Ecol.

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Three benthic microbial communities from a hypersaline lagoon with tidal influence were studied: a compact microbial mat, a 'fluffy' microbial mat and a non-cohesive diatom-dominated sediment. In each community, qualitative and quantitative analyses of phototrophs, meio-and macrofauna were done. Vertical profiles of oxygen, sulfide and pH were measured at the sediment-water interface using microelectrodes. Physico-chemical properties of the water column were also assessed. The most compact mat, dominated by Microcoleus chthonoplastes, had the highest photosynthetic biomass, while meio-and macrofauna were nearly absent. The compact mat showed the steepest physico-chemical microgradients and the highest fluxes of oxygen and sulfide. The 'fluffy' mat had an areal amount of chl a similar to the compact mat and contained a higher abundance of meiofauna. This mat showed the deepest oxic layer. The diatom-dominated sediment comprised a high abundance of macrofauna, but meiofauna were very scarce. This community presented relatively smoother microgradients and intermediate values of internal fluxes of oxygen. Our results show the close relationship between the structure of the microbenthic communities, net metabolism, and the exchange of mass at the water-sediment interface. Changes in biotic and abiotic factors determined the spatial distribution of each microbial community. KEY WORDS: Microbenthic community · Microbial mat · Meiofauna · Macrofauna · Microelectrodes · Biotic factors · Abiotic factors Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 38: [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69] 2005 ments. Nitrogen fixation (Dubinin et al. 1992), fermentation (Moezelaar et al. 1996), the use of sulfide as an electron source (de Wit & van Gemerden 1989, van den Hoek et al. 1995, and the presence of some UV-protective substances (Garcia-Pichel & Castenholz 1991) have been demonstrated in some cyanobacteria, allowing these microorganisms to survive under very stressful and dynamic conditions (high irradiance, salinity, temperature). However, these physiological adaptations do not explain why microbial mats are usually absent in more moderate environmental conditions. Meio-and macrofauna can also play an important role in controlling microbial mat development in coastal environments. Under moderate environmental conditions, e.g. coastal environments, meio-and macrofauna reduce primary producer concentration due to a high grazing activity (Hargrave 1970, Connor et al. 1982, and thus these mild conditions prevent mat accretion , Awramik 1984. It has been classically postulated that extreme conditions like high salinities in hypersaline environments (Pierson et al. 1987, Wieland & Kühl 2000, periodic dryings (Lassen et al. 1992), or high temperatures from thermal sources (Castenholz 1984) can limit meio-and macrofauna growth, allowing the development of microbial mats. However, few studies have quantified meio-and macrofauna in microbial mat...

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Carbohydrate secretion by phototrophic communities in tidal sediments

Cited by 99 publications

References 35 publications

Sediment properties influencing upwelling spectral reflectance signatures: The “biofilm gel effect”

Sediment properties influencing upwelling spectral reflectance signatures: The “biofilm gel effect”

Interaction between Estuarine Microphytobenthos and Physical Forcings: The Role of Atmospheric and Sedimentary Factors

Microbenthos in a hypersaline tidal lagoon: factors affecting microhabitat, community structure and mass exchange at the sediment-water interface

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