Spectral Wave-Driven Bedload Transport Across a Coral Reef Flat/Lagoon Complex

Rosenberger, Kurt J.; Storlazzi, Curt D.; Cheriton, Olivia M.; Pomeroy, Andrew; Hansen, Jeff E.; Lowe, Ryan J.; Buckley, Mark

doi:10.3389/fmars.2020.513020

Cited by 7 publications

(17 citation statements)

References 36 publications

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“…When the results of this study are combined with the bedload transport rates determined by Rosenberger et al. (2020), the average rate of total sediment flux from the reef at T2 toward the lagoon at T3 is 1.3 kg m −2 .…”

Section: Discussionmentioning

confidence: 61%

“…Murray et al, 2011;Sleath & Wallbridge, 2002), or (iii) the composition of the bed sediment changed. It is difficult to determine the precise cause of this reduction in the sediment based on the data in this study alone; however, Rosenberger et al (2020) argued based on a detailed analysis of the bedload dynamics that bed sediment limitation was likely to be a key factor. Our results demonstrate that once the bed is flat, there was little SSF and SSC was reduced.…”

Section: Contribution Of Suspended-sediment Flux To Total Fluxmentioning

confidence: 86%

“…Rosenberger et al. (2020) showed that ripples are present on the bed at both the inner reef flat at T2 and in the lagoon at T3, but were not observed on the outer reef flat at T1. Despite the absence of organized ripples on the reef flat, the phase observations in this study suggests that vortices develop and suspend sediment from the bed, perhaps due to reef flat bed variability (e.g., roughness).…”

Section: Discussionmentioning

confidence: 99%

“…For this reef system, and the observed forcing conditions, bedload is the dominant sediment transport mechanism. When the results of this study are combined with the bedload transport rates determined by Rosenberger et al (2020), the average rate of total sediment flux from the reef at T2 toward the lagoon at T3 is 1.3 kg m −2 .…”

Section: Contribution Of Suspended-sediment Flux To Total Fluxmentioning

confidence: 91%

“…In that field experiment, data were collected spatially and vertically through the water column across the reef and lagoon. Combined with bedform migration measurements (Rosenberger et al., 2020), these data provide a unique opportunity to quantify cross‐reef hydrodynamics and SSC, as well as to determine the relative contribution of both SSF and bedload to the total sediment flux.…”

Section: Methodsmentioning

confidence: 99%

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The Contribution of Currents, Sea‐Swell Waves, and Infragravity Waves to Suspended‐Sediment Transport Across a Coral Reef‐Lagoon System

et al. 2021

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Tropical beaches protect and support communities of hundreds of millions of people globally (Hoegh-Guldberg et al., 2019). These beaches are primarily accumulations of sediment derived from the calcium carbonate skeletal remains of organisms such as coral, crustose coralline algae, and mollusks from adjacent coral reefs (Perry & Hepburn, 2008). When these skeletal remains break down into particle sizes that can Abstract Coral reefs generate substantial volumes of carbonate sediment, which is redistributed throughout the reef-lagoon system. However, there is little understanding of the specific processes that transport this sediment produced on the outer portions of coral reefs throughout a reef-lagoon system. Furthermore, the separate contributions of currents, sea-swell waves, and infragravity waves to transport, which are all strongly influenced by the presence of a reef, is not fully understood. Here, we show that in reef-lagoon systems most suspended sediment is transported close to the seabed and can, at times, be suspended higher in the water column during oscillatory flow transitions (i.e., near slack flow) at sea-swell wave frequencies, and during the peak onshore oscillatory velocity phase at infragravity wave frequencies. While these wave frequencies contribute to the transport of suspended sediment offshore and onshore, respectively, the net flux is small. Mean currents are the primary transport mechanism and responsible for almost 2 orders of magnitude more suspended-sediment flux than sea-swell and infragravity waves. Whilst waves may not be the primary mechanism for the transport of sediment, our results suggest they are an important driver of sediment suspension from the seabed, as well as contributing to the partitioning of sediment grain sizes from the reef to the shoreline. As the ocean wave climate changes, sea level rises, and the composition of reef benthic communities change, the relative importance of mean currents, seaswell waves, and infragravity waves is likely to change, and this will affect how sediment is redistributed throughout reef-lagoon systems. Plain Language Summary Most of the sandy sediment found on coral reef coastlines is produced by organisms living within the reef. This sediment is then transported by waves and currents across the reef and distributed throughout the lagoon. Little is known about these transport processes, including the relative importance of how currents or different types of waves drive transport. This study shows that most of the sediment in the water column (suspended sediment) is transported close to the seabed by mean currents. At times, this sediment can be suspended higher in the water column by short waves (5-25 s) when the flow transitions from being onshore directed to offshore directed, or when the velocities of longer period waves (25-250 s), called infragravity waves, are directed onshore. The timing of the suspension by these waves helps to sort the sediment into different sizes across the system, but the quantity of sediment transported is ...

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Section: Discussionmentioning

confidence: 61%