Accurately measuring the abundance of benthic microalgae in spatially variable habitats

Grinham, Alistair; Carruthers, Tim J. B.; Fisher, Paul L.; Udy, James; Dennison, William C.

doi:10.4319/lom.2007.5.119

Cited by 35 publications

(28 citation statements)

References 33 publications

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“…Thus, the different scales at which algae varied along each of these transects depended on the method of measurement and/or the specific places within each plot that each measurement was made. This emphasizes not only the need for adequate replication at multiple spatial scales to quantify larger-scale trends, but also consideration of the methods being used to estimate micro-algae when different methods reveal different ecological patterns (Grinham et al 2007). …”

Section: Discussionmentioning

confidence: 99%

Complex and inconsistent patterns of variation in benthos, micro-algae and sediment over multiple spatial scales

Chapman¹,

Tolhurst²,

Murphy³

et al. 2010

Mar. Ecol. Prog. Ser.

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Because of their close physical relationship, it is often assumed that there are strong functional relationships between sediments and biota. Yet, there have been few studies of the characteristics of sediments over multiple spatial scales, despite evidence that micro-algae and macroand meiofauna vary greatly at cm to km scales. This study quantified variability in macrofauna, micro-algae, and physical and biochemical properties of sediments over scales from 50 cm to km. The benthos was most variable at small scales and, even where there were large mean differences in abundance at large scales, these were small compared to the variation from plot to plot along a shore. Only 1 of 24 analyses showed larger variation at the scale of km than that found at 50 cm. Some measures of microphytobenthos showed large variation at the scale of 100s m or more, but other measures of the same flora did not show similar patterns. Concentrations of sand were consistent at different depths and at large scales, but concentrations of mud were more variable within than among shores. Neither sand nor mud correlated significantly with most biochemical properties of sediments. For sediments, variation at the scale of km was only larger than that of 50 cm in 13 of 57 analyses. To understand the relative importance of ecological processes in determining distributions and abundances, it is important to get quantitative data on the scales at which organisms or habitats vary. These are the scales at which ecological processes are likely to have large effects because large-scale processes are unlikely to explain variation at much smaller scales. The importance of small-scale variability in sediments and the associated biota is discussed in terms of sampling protocols for understanding ecological processes, or for assessing impact or restoration.

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Section: Discussionmentioning

confidence: 99%

Complex and inconsistent patterns of variation in benthos, micro-algae and sediment over multiple spatial scales

Chapman¹,

Tolhurst²,

Murphy³

et al. 2010

Mar. Ecol. Prog. Ser.

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“…Samples were stored on dry ice in the field and at -80°C in the laboratory. Photosynthetic pigments were extracted based on a method modified from Grinham et al (2007), where 100% chilled acetone (wt:vol ratio of 2:5) and a canthaxanthin internal standard were added to the samples, which were then stored at -20°C for 24 h. Thereafter, samples were sonicated for 8 min on ice and the resulting solution was centrifuged. The supernatant was then passed through 0.45 µm PTFE syringe filters (Waters Corporation).…”

Section: Methodsmentioning

confidence: 99%

Differences in microphytobenthos and macrofaunal abundances associated with groundwater discharge in the intertidal zone

Waska¹,

Kim²

2010

Mar. Ecol. Prog. Ser.

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We investigated the impact of intertidal groundwater seepage on benthic microalgae and macrofauna in 4 study sites located in 2 large tidal flat ecosystems along the western coast of Korea by comparing the chemical, physical, and biological characteristics of 'glossy' seepage sites with those of nearby areas without visually distinct groundwater discharge (dry sediment surface). At 3 of the 4 sites, sediment properties as well as pore water chemistry were similar in groundwater seepage and dry areas. At the 4th study site, the groundwater seepage areas were more coarsegrained compared to the dry areas. Here, the groundwater seepage also had lower salinity and higher nutrient concentrations than the pore water of the dry area and the seawater in a nearby tide pool. Although diatoms were the dominant algal class in seepage and dry areas alike, the seepage areas in 3 of the sites had elevated contributions of other marker pigments such as chlorophyll (chl) b compared to the dry areas. Chl a concentrations were higher in all seepage areas compared to dry areas, and all dry areas had high pheophytin a:chl a ratios, indicating a substantial amount of degraded algal material. In the seepage areas of 3 of the sites, we found large numbers of the snail Batillaria cumingi, while crab burrows of Scopimera sp. were only present in the neighboring dry areas. Correlations of sediment chl a concentrations with physicochemical properties of the ambient pore water indicated that microphytobenthos responded specifically to groundwater seepage, which may provide shelter from desiccation and salt stress during emersion of the tidal flat. Our results suggest that globally common groundwater seepage significantly impacts the ecosystem structures and microphytobenthos production of the tidal flats.KEY WORDS: Groundwater · Seepage · Microphytobenthos · Macrofauna · Intertidal · Pigments · Tidal flat Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 407: [159][160][161][162][163][164][165][166][167][168][169][170][171][172] 2010 Intertidal microphytobenthos, i.e. the assemblage of bottom-living microalgae such as diatoms, is an important contributor to the benthic food chain (MacIntyre et al. 1996, Kang et al. 2003. Through resuspension, microphytobenthos can be transferred to pelagic systems as well (De Jonge & van Beusekom 1992). Furthermore, microphytobenthos can regulate diffusive nutrient fluxes between sediment and the overlying water column (Sundbäck et al. 1991). The relationship between microphytobenthos and ambient nutrient concentrations is often unclear. Generally, benthic microalgae, particularly from muddy sediments, are not nutrient limited (Underwood & Kromkamp 1999), and nutrient enrichment via the water column does not seem to have any effect on microphytobenthos biomass (Hillebrand & Kahlert 2002). On the other hand, microphytobenthos cultures can be maintained well with natural porewater (Admiraal et al. 1982), and microphytobenthos mats in the sandy sediment...

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“…This procedure, although time-consuming and labor-intensive, has been widely used to estimate the spatial structure and temporal dynamics of MPB biomass (Guarini and Blanchard 1998;Brito et al 2009b;Spilmont et al 2011). A troubling feature of this method has been the lack of standardization of the protocol involved, such as sampling core diameter, sampling depth, the number of replicates, or the extraction solvent, which makes it challenging to compare results of different studies (Grinham et al 2007;Brito et al 2009a). A further disadvantage of the method is that it is destructive and does not allow repetitive measurements at the same location.…”

Section: Hyperspectral Imaging Of the Microscale Distribution And Dynmentioning

confidence: 99%

Hyperspectral imaging of the microscale distribution and dynamics of microphytobenthos in intertidal sediments

Chennu¹,

Farber²,

Volkenborn³

et al. 2013

Limnology & Ocean Methods

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511Microphytobenthos (MPB), consisting of benthic phototrophs such as microalgae, cyanobacteria, and dinoflagellates, is the fundament of the trophic food web in coastal ecosystems. In shallow-water environments, such as intertidal flats and estuaries, MPB represents a considerable portion of the autotrophic biomass, accounting for up to 50% of the primary production Nozais et al. 2001;Spilmont et al. 2006). MPB is the predominant food source for many deposit-feeding organisms, and the activity and distribution of MPB profoundly affect nutrient fluxes across the sediment-water interface, sediment geochemistry, as well as sediment morphology and stability (Sundbäck et al. 1991;Montagna et al. 1995;Miller et al. 1996;Stal 2010).The spatio-temporal organization of a community is a prominent issue in ecology. Levin (1992) argued that analysis of large-scale (regional) patterns must integrate effects occurring at smaller scales. Generally, the distribution of MPB is affected by both abiotic processes (e.g., nutrient availability, hydrodynamic exposure, sediment type) and biotic processes (e.g., grazing, competition) through a complex network of interactions. In their reductionist approach to benthic ecology, Miller et al. (1996) argued that studies of interactions with a direct effect on the MPB distribution (so called "isolated first-order interactions") are required to disentangle the complex relationships between the sediment bed, infaunal organisms, and the water column, and for a comprehensive picture AbstractWe describe a novel, field-deployable hyperspectral imaging system, called Hypersub, that allows noninvasive in situ mapping of the microphytobenthos (MPB) biomass distribution with a high spatial (sub-millimeter) and temporal (minutes) resolution over areas of 1 × 1 m. The biomass is derived from a log-transformed and near-infrared corrected reflectance hyperspectral index, which exhibits a linear relationship (R 2 > 0.97) with the chlorophyll a (Chl a) concentration in the euphotic zone of the sediment and depends on the sediment grain size. Deployments of the system revealed that due to factors such as sediment topography, bioturbation, and grazing, the distribution of MPB in intertidal sediments is remarkably heterogeneous, with Chl a concentrations varying laterally by up to 400% of the average value over a distance of 1 cm. Furthermore, due to tidal cycling and diel light variability, MPB concentrations in the top 1 mm of sediments are very dynamic, changing by 40-80% over a few hours due to vertical migration. We argue that the high-resolution hyperspectral imaging method overcomes the inadequate resolution of traditional methods based on sedimentary Chl a extraction, and thus helps improve our understanding of the processes that control benthic primary production in coastal sediments.

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Accurately measuring the abundance of benthic microalgae in spatially variable habitats

Cited by 35 publications

References 33 publications

Complex and inconsistent patterns of variation in benthos, micro-algae and sediment over multiple spatial scales

Complex and inconsistent patterns of variation in benthos, micro-algae and sediment over multiple spatial scales

Differences in microphytobenthos and macrofaunal abundances associated with groundwater discharge in the intertidal zone

Hyperspectral imaging of the microscale distribution and dynamics of microphytobenthos in intertidal sediments

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