Seven ecological and technical attributes for biofilm‐based recovery of shorebird populations in intertidal flat ecosystems

This study describes the daily activity in a simulated high tide situation of four species of hermit crabs (Pagurus criniticornis, Clibanarius antillensis, C. sclopetarius, and C. vittatus) that coexist in an intertidal flat in southeastern Brazil. Observations were done in two-hour intervals during two subsequent days (48 h) in three replicate pools with thirty crabs each. Among species (between and within genera) there was an evident variation in activity patterns, of which three could be distinguished. The circadian activity patterns of C. antillensis and C. vittatus could be characterized as evening and nocturnal, with resting peaks during the morning and afternoon. The circadian activity pattern of C. sclopetarius was characterized by two marked peaks of inactivity, corresponding to dawn and evening, which could represent an intrinsic association with the semi-lunar tidal cycles of the study area. Pagurus criniticornis showed high activity not influenced by day/night conditions during the entire observed period. These activity pattern variations of the studied hermit crabs should be taken into account in designing further experiments. More precise and accurate interspecific behavioral comparisons among species could be achieved in nocturnal experiments, the high activity period of all species.

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Tidal Flat Depositional Response to Neotectonic Cyclic Uplift and Subsidence (1–2 m) as Superimposed on Latest-Holocene Net Sea Level Rise (1.0 m/ka) in a Large Shallow Mesotidal Wave-Dominated Estuary, Willapa Bay, Washington, USA

Journal of Geography and Geology ◽

10.5539/jgg.v10n1p109 ◽

2018 ◽

Vol 10 (1) ◽

pp. 109 ◽

Cited By ~ 1

Author(s):

Curt D. Peterson ◽

Sandy Vanderburgh

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Tidal Flat ◽

Late Holocene ◽

Columbia River ◽

Small Rivers ◽

Intertidal Flat ◽

Sedimentation Rates ◽

Lateral Migration ◽

Willapa Bay

The late-Holocene record of tidal flat deposition in the large shallow Willapa Bay estuary (43 km in length), located in the Columbia River Littoral Cell (CRLC) system (160 km length), was investigated with new vibracores (n=30) and gouge cores (n=8), reaching 2–5 m depth subsurface. Reversing up-core trends of muddy sand to peaty mud deposits in marginal tidal flat settings demonstrate episodic submergence events resulting from cyclic tectonic uplift and subsidence (1–2 m) in the Cascadia subduction zone. These short-term reversals are superimposed on longer-term trends of overall sediment coarsening-up, which represent the transgression of higher-energy sandy tidal flats over pre-existing lower-energy tidal flat mud and peaty mud deposits in late-Holocene time. Fining-up trends associated with channel lateral migration and accretionary bank deposition occurred only infrequently in the broad intertidal flats of Willapa Bay. Vibracores and gouge cores were dated by 14C (n=16) and paleo-subsidence event contacts (n=17). Vibracore median probability 14C ages ranged from 0 to 6,992 yr BP and averaged 2,174 yr BP. Dated sample ages and corresponding depths of tidal flat deposits yield net sedimentation rates of 0.9–1.2 m ka-1, depending on the averaging methods used. Net sedimentation rates in the intertidal flat settings (~1.0 m ka-1) are comparable to the rate of net sea level rise (~1.0 m ka-1), as based on dated paleo-tidal marsh deposits in Willapa Bay. Reported modern inputs of river sand (total=1.77x104 m3 yr-1), from the three small rivers that flow into Willapa Bay, fall well short of the estimated increasing accommodation space (1.9x105 m3 yr-1) in the intertidal (MLLW-MHHW) setting (1.9x108 m2 surface area) during the last 3 ka, or 3.0 m of sea level rise. The under-supply of tributary sand permitted the influx of littoral sand (1.1x105 m3 yr-1) into Willapa Bay, as based on the net sedimentation rate (~1.0 m ka-1) and textural composition (average 60 % littoral sand) in analyzed core sections (n=179). The long-term littoral sand sink in Willapa Bay’s intertidal setting (55 % of total estuary area) is estimated to be about 5 % of the Columbia River supply of sand to the CRLC system, and about 30% relative to the littoral sand accumulated in barrier spits and beach plains during late-Holocene time. A 2.0 m rise in future sea level could yield a littoral sand sink of 2.2x108 m3 in the Willapa Bay intertidal setting, resulting in an equivalent shoreline retreat of 600 m along a 50 km distance of the barrier spit and beach plains that are located adjacent to the Willapa Bay tidal inlet. Willapa Bay serves as proxy for potential littoral sand sinks in other shallow mesotidal estuary-barrier-beach systems around the world following future global sea level rise.

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Sediment turnover by the stalk-eyed mud crab Hemiplax hirtipes (Brachyura: Ocypodoidea) on an intertidal flat in southeastern New Zealand

New Zealand Journal of Marine and Freshwater Research ◽

10.1080/00288330.2016.1220956 ◽

2016 ◽

Vol 51 (2) ◽

pp. 279-294

Author(s):

AA Rowden

Keyword(s):

New Zealand ◽

Intertidal Flat ◽

Mud Crab

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Ecological memory mitigates negative impacts of disturbance on biomass production in benthic diatom metacommunities

10.1101/2020.07.23.217448 ◽

2020 ◽

Author(s):

Friederike G. Engel ◽

Birte Matthiessen ◽

Rosyta Andriana ◽

Britas Klemens Eriksson

Keyword(s):

Benthic Diatom ◽

Species Pool ◽

Intertidal Flat ◽

Ecological Communities ◽

Response Diversity ◽

Extreme Heat Events ◽

Ecological Memory ◽

Mechanical Disturbance ◽

Diatom Communities ◽

Negative Impacts

AbstractDisturbance events to coastal habitats such as extreme heat events, storms, or floods have increased in magnitude and frequency in recent years due to anthropogenic climate change and the destruction of habitats. These events constitute a major threat to many ecological communities and global biodiversity. Disturbance history influences ecosystem response to novel disturbances such that communities that have previously been exposed to disturbances should be more resilient to new disturbances compared to previously sheltered communities. This principle is defined as ecological memory. Resilience should also increase with access to a larger species pool, because a larger species pool increases species and response diversity of a community. One possibility of increasing the local species pool is connectivity via adequate dispersal between habitat patches with different species compositions in metacommunities. In a laboratory experiment, we exposed benthic diatom communities of different origin to a mechanical disturbance, simulated dispersal in half of the communities, and measured their chlorophyll a concentration over time. The local diatom communities originated from different locations on an intertidal flat that varied in hydrodynamic exposure history. Hydrodynamic exposure disturbs the sediment, and thereby determines sediment properties and the composition of intertidal diatom communities. In the experiment, disturbance negatively affected chlorophyll a concentration across all treatments. However, the response to disturbance depended on the ecological memory of the communities; the more exposed areas the communities originated from, the less negative was the effect of the mechanical disturbance. Interestingly, dispersal did not mitigate the negative impacts of disturbance in any of the communities. Our results highlight the importance of ecological memory for ecosystem functioning and demonstrate the limitations of patch connectivity to alleviate the impacts of disturbance events in metacommunities.

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Delineation of Sedimentary Facies and Groundwater-Sea Water Disposition in an Intertidal Zone of the Bay of Bengal using GPR and VES

Journal of Environmental and Engineering Geophysics ◽

10.2113/jeeg23.2.235 ◽

2018 ◽

Vol 23 (2) ◽

pp. 235-249

Author(s):

Mrinal Kanti Layek ◽

Palash Debnath ◽

Probal Sengupta ◽

Abhijit Mukherjee

Keyword(s):

Bay Of Bengal ◽

Sea Water ◽

Water Saturation ◽

Water Discharge ◽

Ground Surface ◽

Sedimentary Facies ◽

Intertidal Flat ◽

Sediment Layer ◽

Fresh Groundwater ◽

Water Saturated

A combination of geophysical study including ground penetrating radar (GPR) and vertical electrical sounding (VES) was done to identify different shallow-subsurface depositional features in an intertidal coast of the eastern parts of India, adjoining the Bay of Bengal (BoB) (Chandipur, Odisha state). The study was aimed to understand the variation of sedimentary depositional sequences, prograding to the ocean from land, as well as towards the confluence of a river channel with the BoB. Six VES points and 85 GPR traverses were taken in the intertidal flat. The data were calibrated with sedimentary sequences retrieved from simultaneously drilled boreholes in four locations. Resistivity data clearly demonstrate the subsurface sediment layer boundaries with water saturation variability, up to 156 m below ground surface (bgs). The data suggest thickening of brackish water saturated clay layers towards the southwestern part. GPR data were capable of resolving the geometry of intertidal dunes, buried palaeo-channels, erosional surface, water table, eolian deposit of sand, and washover delta depositional features which are all present in this study area. Several erosional surfaces, related to sedimentary processes, e.g., delta overwash processes, were clearly demarcated. The study also successfully identified and visualized the saline-fresh groundwater interfaces and submarine ground water discharge (SGD) zones. Consequently, based on these data, a conceptual model of the depositional and erosional history of the sedimentation of the area, as well as the coastal hydrogeological disposition, was conceived.

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