Benthic Habitat Variations over Tidal Ridges, North Sea, the Netherlands

Dijk, T.A.G.P. van; Dalfsen, J.A. van; Lancker, V. Van; Overmeeren, R.A. van; Heteren, Sytze van; Doornenbal, Pieter

doi:10.1016/b978-0-12-385140-6.00013-x

Cited by 37 publications

(40 citation statements)

References 2 publications

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“…Bed patterns are common features in sandy coastal shelf seas and estuaries, shaped by the interplay of tides, currents, waves, and biology. Various types of offshore bed forms can be found, for instance, sand banks (Stride, 1982), long bed waves (Knaapen et al, 2001), tidal sand waves (van Veen, 1935), mega ripples (Stride, 1982), and sand ripples (Allen, 1984). Of all the described bed forms, sand waves are the most relevant to study as their dynamic behavior can pose a threat to offshore civil engineering constructions, such as pipelines (Németh et al, 2003) and cables to wind farms (Roetert et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Video Transects Reveal That Tidal Sand Waves Affect the Spatial Distribution of Benthic Organisms and Sand Ripples

Damveld

Reijden

Cheng

et al. 2018

Geophysical Research Letters

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The sandy seabed of shallow coastal shelf seas displays morphological patterns of various dimensions. The seabed also harbors a rich ecosystem. Increasing pressure from human‐induced disturbances necessitates further study on drivers of benthic community distributions over morphological patterns. Moreover, a greater understanding of the sand ripple distribution over tidal sand waves may improve morphological model predictions. Here we analyzed the biotic abundance and ripple morphology in sand wave troughs and crests using video transects. We found that both the epibenthos and endobenthos are significantly more abundant in sand wave troughs, where ripples are less abundant and more irregularly shaped. Finally, we show that camera systems are relatively quick and effective tools to study biotic spatial patterns in relation to seabed morphology.

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Section: Introductionmentioning

confidence: 99%

Video Transects Reveal That Tidal Sand Waves Affect the Spatial Distribution of Benthic Organisms and Sand Ripples

Damveld

Reijden

Cheng

et al. 2018

Geophysical Research Letters

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“…Superimposed on the sand waves are megaripples [21], which have a wavelength of 15 m, where some wavelengths are as short as 10 m and others as long as 25 m. The megaripples move faster than the sand waves, in the scale of weeks [21,23] or even hours [24]. The troughs of the Brown Bank consist of muddy sediments mixed with gravel and shell fragments and the crests contain well sorted medium sand [17].…”

Section: Study Areamentioning

confidence: 99%

“…The Brown Bank area of the North Sea (Figure 1a; data source: [16]) exhibits sand waves of various sizes, namely, sand banks (Figure 1b), sand waves ( Figure 1c), and megaripples ( Figure 1d) (see Section 2.1 for definitions). Although the main sediment is sand, there is a variation of muddy sediments mixed with gravel and shell fragments in the deep troughs and well sorted medium sand on the crest [17]. Also, infauna species diversity and abundance is much higher in the troughs than on the crest [17].…”

Section: Introductionmentioning

confidence: 99%

“…Although the main sediment is sand, there is a variation of muddy sediments mixed with gravel and shell fragments in the deep troughs and well sorted medium sand on the crest [17]. Also, infauna species diversity and abundance is much higher in the troughs than on the crest [17]. A high resolution classification map of seafloor sediments in a sand wave area provides valuable information for both marine biologists, who study the spatial variability of seabed habitats and benthic communities, and modelers of seafloor dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Seafloor Classification in a Sand Wave Environment on the Dutch Continental Shelf Using Multibeam Echosounder Backscatter Data

et al. 2019

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High resolution maps of sandy seafloors are valuable to understand seafloor dynamics, plan engineering projects, and create detailed benthic habitat maps. This paper presents multibeam echosounder backscatter classification results of the Brown Bank area of the North Sea. We apply the Bayesian classification method in a megaripple and sand wave area with significant slopes. Prior to the classification, corrections are implemented to account for the slopes. This includes corrections on the backscatter value and its corresponding incident angle. A trade-off in classification resolutions is found. A higher geo-acoustic resolution is obtained at the price of losing spatial resolution, however, the Bayesian classification method remains robust with respect to these trade-off decisions. The classification results are compared to grab sample particle size analysis and classified video footage. In non-distinctive sedimentary environments, the acoustic classes are not attributed to only the mean grain size of the grab samples but to the full spectrum of the grain sizes. Finally, we show the Bayesian classification results can be used to characterize the sedimentary composition of megaripples. Coarser sediments were found in the troughs and on the crests, finer sediments on the stoss slopes and a mixture of sediments on the lee slopes.

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“…Crests and troughs of bedforms of varying size (ranging from ripples to megaripples, ridges and runnels, shoreface-connected ridges and sand waves) have been found to have different abiotic conditions (such as sediment grain size and organic matter content) but also to support different benthic communities (e.g. Barros et al 2004, Baptist et al 2006, van Dijk et al 2012, Zonneveld et al 2014, Markert et al 2015. This habitat differentiation, induced by hydrodynamic forces, may counteract the negative effect of the stress of hydro dynamics and disturbance by dune migration on species richness (e.g.…”

Section: Introductionmentioning

confidence: 99%

Response of intertidal benthic macrofauna to migrating megaripples and hydrodynamics

Wal¹,

Ysebaert²,

Herman³

2017

Mar. Ecol. Prog. Ser.

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Migrating flow-transverse mesoscale intertidal bedforms (megaripples or dunes) may pose disturbance but may also provide heterogeneity in microhabitats to the inhabiting fauna. We investigated how the macrofauna community responds to these migrating intertidal bedforms, based on surveys in the Westerschelde estuary. Considering the entire estuary, lowand high-energy intertidal areas differed in macrofauna, and high-energy flat areas had a macrofauna community intermediate to those in low-energy flat areas and high-energy areas with megaripples. In megaripple areas on a polyhaline and a mesohaline tidal flat, the macrofauna community depended on hydrodynamics, morphodynamics, grain size, elevation and steep ness of the megaripples. The relative importance of the environmental variables for structuring the macrofauna community differed for each site. Within the megaripples, conditions on crests, at flanks and in troughs were distinctly different: crests had more chl a and coarser sediment than troughs, while flanks had intermediate levels; troughs were higher in carbon and mud content than flanks and crests. The microhabitats supported a different macrofauna community but with a very large overlap in species. Troughs typically had higher species richness, while crests had higher densities of, in particular, (mobile) surface deposit feeders. Part of the macrofauna could benefit from the habitat heterogeneity within the megaripples, but the effect was relatively small. The distribution of macrofauna in the intertidal zone was particularly regulated by overall current velocities and bedform morphodynamics.

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Benthic Habitat Variations over Tidal Ridges, North Sea, the Netherlands

Cited by 37 publications

References 2 publications

Video Transects Reveal That Tidal Sand Waves Affect the Spatial Distribution of Benthic Organisms and Sand Ripples

Video Transects Reveal That Tidal Sand Waves Affect the Spatial Distribution of Benthic Organisms and Sand Ripples

Seafloor Classification in a Sand Wave Environment on the Dutch Continental Shelf Using Multibeam Echosounder Backscatter Data

Response of intertidal benthic macrofauna to migrating megaripples and hydrodynamics

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