Dominant macrobenthic populations experience sustained impacts from annual disposal of fine sediments on sandy beaches

Manning, Lisa M.; Peterson, Charles H.; Bishop, Melanie J.

doi:10.3354/meps10870

Cited by 30 publications

(17 citation statements)

References 42 publications

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“…These results regarding Emerita analoga and polychaetes conflict with the findings of previous studies, which reported pronounced negative effects of replenishment on Emerita talpoida (Hayden & Dolan, 1974;Peterson et al, 2000aPeterson et al, , 2006Peterson et al, , 2014Leewis et al, 2012;Manning et al, 2014) and positive or neutral effects on Scolelepis sp. and/or polychaetes in general (Menn et al, 2003;Peterson et al, 2006Peterson et al, , 2014Leewis et al, 2012;Manning et al, 2014; but see Schlacher and Thompson, 2012). The response of E. analoga may be explained in part by processes other than replenishment that produce boom-bust cycles.…”

Section: Discussioncontrasting

confidence: 99%

“…Previous studies of the effects of replenishment on polychaetes (Menn et al, 2003;Leewis et al, 2012;Manning et al, 2014;Peterson et al, 2006Peterson et al, , 2014 often focused on a single species, Scolelepis squamata. None reported long-term negative effects and in some cases replenishment had a positive effect on the polychaete(s) studied (Menn et al, 2003;Leewis et al, 2012;Manning et al, 2014). In our study, Thoracophelia sp., Nephtys californiensis, Hemipodia simplex, Naineris dendritica, Orbinia johnsoni, and unknown polychaetes accounted for a large proportion (24%) of all collected invertebrates, were found in approximately equal numbers, and in aggregate were twice as abundant as Scolelepis sp.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of beach replenishment on intertidal invertebrates: A 15-month, eight beach study.

Wooldridge

Henter

Kohn

2016

Estuarine, Coastal and Shelf Science

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Beach replenishment is an increasingly popular means to remediate coastal erosion, but no consensus exists regarding how long replenishment affects sandy beach intertidal invertebrates, key components of beach ecosystems. We monitored the intertidal invertebrate community for fifteen months following a replenishment project at eight beaches, each with replenished and control sections, across San Diego County. Nearly all taxa showed major declines in abundance immediately following replenishment. Populations of talitrid amphipods and the bean clam Donax gouldii recovered within one year, sooner than in previous studies. On some beaches, populations of the mole crab Emerita analoga bloomed four months after replenishment and were more numerous on replenished portions of beaches at that time. Mole crab populations subsequently declined and no longer differed by treatment. The polychaete community, composed of Scolelepis sp. and several other numerically important taxa, showed a strong replenishment-induced reduction in abundance that persisted through the end of the study. The large negative effect of replenishment on polychaetes, coupled with their overall importance to the invertebrate community, resulted in a more than twofold reduction in overall invertebrate abundance on replenished beaches at 15 months. Such reductions may have far reaching consequences for sandy beach ecosystems, as community declines can reduce prey availability for shorebirds and fish. As this and other recent studies have revealed longer times for the recovery of intertidal invertebrates than previously observed, longer study periods and more cautious estimates regarding the magnitude, variability, and duration of impacts of beach replenishment for management decision-making are warranted.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effects of beach replenishment on intertidal invertebrates: A 15-month, eight beach study.

Wooldridge

Henter

Kohn

2016

Estuarine, Coastal and Shelf Science

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“…Conversely, juvenile, recently molted, and gravid female crabs may have increased susceptibility to the effects of burial and forces associated with the lateral surge. Crab size and reproductive state should be considered to ameliorate negative effects of deposition events on sensitive stages [3]. Based on size-frequency measurements from crab pot deployments, most crabs observed at BVLs were adults 100 – 170 mm carapace width, and densities of smaller juvenile crabs were generally lower in nearshore samples compared to estuary habitat during the period of deposition operations [39, 40] However, new recruits < 30 mm were observed during 2016 in both video and crab pot samples.…”

Section: Discussionmentioning

confidence: 99%

“…Recent advances in dredged sediment management include recognition of the potential to mitigate areas of environmental degradation with judicious sediment placement [1–3]. Such “beneficial uses” include creation, restoration, and maintenance of wetland habitat, and nourishment of eroding ocean beaches.…”

Section: Introductionmentioning

confidence: 99%

Cover letter RE “Video observations of the acute effects of dredged sediment deposition on mobile epifauna”

Roegner

Fields

Henkel

2018

Preprint

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The “beneficial uses” of dredged sediment are increasingly being explored for habitat restoration and beach nourishment. At ocean and nearshore deposition sites, any beneficial use must be tempered by evaluating impacts to the benthos. We studied a site at the mouth of the Columbia River where a “thin-layer” sediment deposition method was employed to minimize mounding and disperse sediment within a prescribed area. We used baited benthic video landers (BVLs) in a Before-After Control-Impact (BACI) experimental design to test the acute effects of sediment deposition on the Dungeness crab (Cancer magister) and dog whelk (Nassarius spp). We considered the acute effects of both sediment deposition depths and the lateral surge (the turbidity front transiting the seafloor). Observations revealed sedimentation levels were limited (< 4 cm) and likely posed no direct threat to epifauna. Video and instrument readings showed the lateral surge to impact the BVLs as a 2 to 3 m/s sediment-laden front. Crabs were significantly impacted, while gastropods were more resistant to dislodgment. However, the high velocity impact was relatively brief (5 to 7 min). Further, crabs often returned to forage at BVLs after a mean lag of about 20 min post-impact. These results indicate an acute but ephemeral impact effect on crab, and support use of the thin-layer deposition method to minimize burial. The BVLs in a BACI experimental design were an effective means of measuring sediment impacts to mobile epifauna, and video observations were informative for understanding lateral surge dynamics and the behavioral interactions of organisms.

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“…Grain size dictates the makeup of benthic communities (e.g., [3][4][5][6]); even temporally varying fine-scale sedimentological variations such as sedimentological differences between peaks and troughs of mega ripples can force differences in community structure [7]. Therefore, anthropogenically forced variations in grain size can affect community structure [8,9]. From a morphodynamic perspective, grain size and cohesive properties not only dictate thresholds of erosion and deposition [10,11]-beach profile is related to grain size, as well e.g., [12,13].…”

Section: Introductionmentioning

confidence: 99%

The Use of Unmanned Aerial Systems to Map Intertidal Sediment

et al. 2018

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This paper describes a new methodology to map intertidal sediment using a commercially available unmanned aerial system (UAS). A fixed-wing UAS was flown with both thermal and multispectral cameras over three study sites comprising of sandy and muddy areas. Thermal signatures of sediment type were not observable in the recorded data and therefore only the multispectral results were used in the sediment classification. The multispectral camera consisted of a Red-Green-Blue (RGB) camera and four multispectral sensors covering the green, red, red edge and near-infrared bands. Statistically significant correlations (>99%) were noted between the multispectral reflectance and both moisture content and median grain size. The best correlation against median grain size was found with the near-infrared band. Three classification methodologies were tested to split the intertidal area into sand and mud: k-means clustering, artificial neural networks, and the random forest approach. Classification methodologies were tested with nine input subsets of the available data channels, including transforming the RGB colorspace to the Hue-Saturation-Value (HSV) colorspace. The classification approach that gave the best performance, based on the j-index, was when an artificial neural network was utilized with near-infrared reflectance and HSV color as input data. Classification performance ranged from good to excellent, with values of Youden's j-index ranging from 0.6 to 0.97 depending on flight date and site.

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Dominant macrobenthic populations experience sustained impacts from annual disposal of fine sediments on sandy beaches

Abstract: Disposal onto a sandy beach of sediments dredged from a navigation channel suppresses abundances of most intertidal invertebrates and increases surf-zone turbidity (insets).

Cited by 30 publications

References 42 publications

Effects of beach replenishment on intertidal invertebrates: A 15-month, eight beach study.

Effects of beach replenishment on intertidal invertebrates: A 15-month, eight beach study.

Cover letter RE “Video observations of the acute effects of dredged sediment deposition on mobile epifauna”

The Use of Unmanned Aerial Systems to Map Intertidal Sediment

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