Wave actions and topography determine the small-scale spatial distribution of newly settled Asari clams Ruditapes philippinarum on a tidal flat

Nambu, Ryogen; Saito, Hajime; Tanaka, Yoshio; Higano, Junya; Kuwahara, Hisami

doi:10.1016/j.ecss.2011.11.010

Cited by 12 publications

(7 citation statements)

References 26 publications

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“…We show that the magnitude of short-term bed-level variations is high comparing to the net bed-level changes at both study sites. It implies that the intertidal environment has a high level of bed-level dynamics for the establishment of new vegetation or benthos 23 , 24 , 26 – 29 . It is apparent that the magnitude of daily bed-level dynamics increases towards the seaward direction with the enhanced total BSS from tidal current and wave ( τ max ).…”

Section: Discussionmentioning

confidence: 99%

Patterns and drivers of daily bed-level dynamics on two tidal flats with contrasting wave exposure

Yao

Wal

et al. 2017

Sci Rep

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Short-term bed-level dynamics has been identified as one of the main factors affecting biota establishment or retreat on tidal flats. However, due to a lack of proper instruments and intensive labour involved, the pattern and drivers of daily bed-level dynamics are largely unexplored in a spatiotemporal context. In this study, 12 newly-developed automatic bed-level sensors were deployed for nearly 15 months on two tidal flats with contrasting wave exposure, proving an unique dataset of daily bed-level changes and hydrodynamic forcing. By analysing the data, we show that (1) a general steepening trend exists on both tidal flats, even with contrasting wave exposure and different bed sediment grain size; (2) daily morphodynamics level increases towards the sea; (3) tidal forcing sets the general morphological evolution pattern at both sites; (4) wave forcing induces short-term bed-level fluctuations at the wave-exposed site, but similar effect is not seen at the sheltered site with smaller waves; (5) storms provoke aggravated erosion, but the impact is conditioned by tidal levels. This study provides insights in the pattern and drivers of daily intertidal bed-level dynamics, thereby setting a template for future high-resolution field monitoring programmes and inviting in-depth morphodynamic modelling for improved understanding and predictive capability.

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Section: Discussionmentioning

confidence: 99%

Patterns and drivers of daily bed-level dynamics on two tidal flats with contrasting wave exposure

Yao

Wal

et al. 2017

Sci Rep

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“…The long-term dynamics of bare tidal flats is widely recognized as being important in the overall sustainability of coastal ecosystems, such as saltmarshes and mangroves (Fagherazzi et al, 2006;van der Wal et al, 2008;Fagherazzi, 2010, 2013). Recent studies have also identified the short-term dynamics of bed level as a major physical disturbance constraining the establishment of intertidal biotas (Bouma et al, 2001(Bouma et al, , 2016Nambu et al, 2012;Balke et al, 2013Balke et al, , 2014Balke et al, , 2015. Thus, understanding intertidal morphodynamics is key to preserving ecosystems and their various services (Barbier et al, 2008;Arkema et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

Wal

Cai

et al. 2018

Geomorphology

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Highlights: High-resolution field data supports dynamic equilibrium theory for tidal flats  Empirical Orthogonal Function analysis revealed dynamic equilibrium behaviour  Tide-induced bottom shear stress shown to regulate morphology of macrotidal systems  Lower sediment input may have induced the observed pattern of erosion Abstract Dynamic Equilibrium Theory (DET) has been applied to tidal flats to systematically explain intertidal morphological responses to various distributions of bed shear stress (BSS). However, it is difficult to verify this theory with field observations because of the discrepancy between the idealized conceptions of theory and the complex reality of intertidal dynamics. The core relation between intertidal morphodynamics and BSS distribution can be easily masked by noise in complex datasets, leading to conclusions of insufficient field evidence to support DET. In the current study, hydrodynamic and morphodynamic data were monitored daily for one year on two tidal flats with contrasting wave exposures. BSS distribution was obtained by validated numerical models. Tidal flat dynamic equilibrium behaviour and BSS were linked via Empirical Orthogonal Function (EOF) analysis. We show that the principal morphodynamic modes corresponded well with the respective modes of BSS found at both sites. Tide-induced BSS was the dominant force at both sites, regardless of the level of wave exposure. The overall erosional and steepening trend found at the two flats can be attributed to the prevailing action of tidal forcing and reduced sediment supply. Hence, EOF analysis confirmed that tidal flat morphodynamics are consistent with DET, providing both field and model evidence to support this theory.

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“…Different parameters concur to determine the spatial distribution of Manila clam settlement areas and adult stocks. In the first case, hydrodynamic and topographical conditions are driving factors (Nambu et al 2012), whereas recruitment success is affected by multiple factors such as broodstock quality, meteo-climatic conditions during spawning, hydrodynamics, mortality rate of larvae and juveniles, and predation (Ólafsson et al 1994).…”

Section: Discussionmentioning

confidence: 99%

Clam culture in the Venice lagoon: stock assessment of Manila clam (Venerupis philippinarum) populations at a nursery site and management proposals to increase clam farming sustainability

Brusà

Cacciatore

Ponis

et al. 2013

Aquat. Living Resour.

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-The Venice lagoon is the main Manila clam (Venerupis philippinarum) production site in Europe. Following the unsustainable exploitation of this site (free-access fishery) local authorities have been striving to regulate fishing activities and most clams are produced using mollusc culture techniques based on wild spat harvesting and on its seeding in appropriate, designated culture areas. Therefore, the quality and abundance of wild clam stocks are critical factors that could limit the full development of this activity. The present study aims at assessing Manila clam stocks (spat, adults per square meter) using ordinary kriging, in an area of the Venice lagoon located near the Porto Marghera industrial zone. Previous studies have identified this area as one of the most important natural clam settlement sites in the Venice lagoon. The study area was approximately 1085 ha; 46 sampling stations were examined. Stock assessment (animals were grouped by size and age group), biomass and correlation with sediment texture were evaluated. The results obtained and comparisons with studies from the literature enabled an estimation of clam recruitment potential and an analysis of the conservation status of clam stocks. Thereafter, in view of a full reclamation and an ecological restoration of the study area, different measures are proposed for the sustainable use of this area that include the establishment of a biological protection area and a shared and rational management of the nursery area; these measures could potentially increase the sustainability of clam culture in the Venice lagoon.

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Wave actions and topography determine the small-scale spatial distribution of newly settled Asari clams Ruditapes philippinarum on a tidal flat

Cited by 12 publications

References 26 publications

Patterns and drivers of daily bed-level dynamics on two tidal flats with contrasting wave exposure

Patterns and drivers of daily bed-level dynamics on two tidal flats with contrasting wave exposure

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

Clam culture in the Venice lagoon: stock assessment of Manila clam (Venerupis philippinarum) populations at a nursery site and management proposals to increase clam farming sustainability

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