Spatial variation of chlorophyll on estuarine mudflats determined by field-based remote sensing

Murphy, Richard J.; Tolhurst, T.J.; Chapman, M. G.; Underwood, A. J.

doi:10.3354/meps07456

Cited by 41 publications

(17 citation statements)

References 68 publications

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“…Microphytobenthos is a community with a very variable spatial coverage at scales ranging from a few millimeters to kilometers (e.g. Seuront and Spilmont, 2002;Murphy et al, 2008;Davoult et al, 2009;Spilmont et al, 2011). It is therefore essential to have an overall evaluation of the community at the scale of the intertidal system since the description of its spatial structure is a prerequisite to understand processes (Murphy et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

Seasonality of microphytobenthos revealed by remote-sensing in a South European estuary

Brito

Benyoucef

Jesus

et al. 2013

Continental Shelf Research

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Keywords:Microphytobenthos Intertidal flats Temporal and spatial variability Mediterranean Climate NDVI MERIS/SPOT a b s t r a c tThe spatio-temporal variation of microphytobenthos (MPB) at the scale of a large estuary (Tagus estuary, Portugal) was studied using a combination of field and satellite remote sensing data during 2003. This is the first attempt to use remote sensing to study MPB in an ecosystem with a Mediterranean-like climate. Satellite pour l'Observation de la Terre (SPOT) and Medium Resolution Imaging Spectrometer (MERIS) images were used to map benthic microalgae through the application of a Normalized Difference Vegetation index (NDVI). A significant relationship between in-situ benthic chlorophyll a measurements and SPOT NDVI values was used to derive a map for biomass spatial distribution.At the scale of the whole intertidal area, NDVI time-series from 2003 revealed that MPB showed clear temporal variations, with lower values observed in summer compared to winter. This seasonal trend was found both in the SPOT and MERIS images and may be the result of extreme high temperatures that inhibit MPB growth. The main MPB biofilms were spatially stable through time at a large scale. Maximum NDVI values during the winter were found in the high shore with decreasing NDVI values towards the low shore. MPB light limitation at the lowest bathymetries is likely to occur in winter due to the high turbidity of Tagus . This study suggests striking differences in MPB seasonal patterns between the northern and southern European estuaries and stresses the need for ecophysiological approaches to investigate the role of thermo-and photo-inhibition as structuring factors for MPB biomass distribution.

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Section: Discussionmentioning

confidence: 99%

Seasonality of microphytobenthos revealed by remote-sensing in a South European estuary

Brito

Benyoucef

Jesus

et al. 2013

Continental Shelf Research

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“…There is, however, little current information about multiple spatial scales of variation, for example from <1 m to km, for a suite of sedimentary variables that simultaneously includes physical properties, fauna and flora (but see Pinckney & Sandulli 1990, Azovsky 2002, Murphy et al 2008 for some components of sediment). Thus, it is not clear how best to sample to detect processes that operate at different spatial scales, nor to determine which scales show large variability that needs to be understood in order to identify ecological processes influencing sediments.…”

Section: Introductionmentioning

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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“…However, handling time is probably much greater for the SFB prey. In addition, macroinfaunal distribution, ab undance, and recruitment are largely cryptic and may be extremely variable (Beukema & de Vlas 1989, Beukema et al 1993, Zwarts & Wanink 1993, Honkoop et al 2006, Van der Wal et al 2008, Chapman et al 2010, whereas microphytobenthic patches are much more visible and, notwithstanding small-scale spatial variability (Murphy et al 2008, Chapman et al 2010, spatially predictable (e.g. following precise high tide isobaths, Méléder et al 2003b).…”

Section: Discussionmentioning

confidence: 99%

Downward trophic shift during breeding migration in the shorebird Calidris mauri (western sandpiper)

Beninger¹,

Elner²,

Morançais³

et al. 2011

Mar. Ecol. Prog. Ser.

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The recent demonstration of mudflat surficial biofilm feeding by western sandpiper Calidris mauri has provided new insight into the feeding ecology of shorebirds. We assessed feeding modes over the migratory cycle, and specifically whether a downward shift in trophic position occurred during the 2004 northward migration from their overwintering areas to the Arctic breeding grounds. We used stable isotope composition and calculated trophic positions of adult western sandpiper at their northward migratory stopover on Roberts Bank, British Columbia, Canada, in 3 animal compartments with increasing turnover times (stomach contents, liver, and muscle). This allowed the retrospective determination of their major diet source types over time frames encompassing the geographical ranges of their previous migratory stopovers and arrival on the Roberts Bank stopover. Detailed taxonomic and photopigment determinations were also performed on stomach contents and surficial biofilm. The Roberts Bank biofilm showed high taxonomic homogeneity among sampling sites, suggesting a qualitatively consistent food source during western sandpiper stopover. A statistically significant downward shift in mean trophic position (TP) occurred between previous migratory stopovers (TP = 3.0 ± 0.5, mean ± SD) and arrival on the Roberts Bank stopover, where the maximum probability densities showed > 70% dietary contribution of benthic diatoms, with a TP = 2.3 ± 0.4, close to the diet of the suspension-feeding bivalves Tapes philippinarum and Mya sp. (TP = 2). Advantages of biofilm over macrofaunal feeding during migration may include decreased handling and search time, as well as greater availability and digestibility of the high-energy carbohydrates needed for flight.

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Spatial variation of chlorophyll on estuarine mudflats determined by field-based remote sensing

Cited by 41 publications

References 68 publications

Seasonality of microphytobenthos revealed by remote-sensing in a South European estuary

Seasonality of microphytobenthos revealed by remote-sensing in a South European estuary

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

Downward trophic shift during breeding migration in the shorebird Calidris mauri (western sandpiper)

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