Fossil maerl beds as coastal indicators of late Holocene palaeo-environmental evolution in the Bay of Brest (Western France)

Ehrhold, Axel; Jouet, Gwénaël; Roy, Pascal Le; Jorry, Stéphan; Grall, Jacques; Reixach, Théo; Lambert, Clément; Gregoire, Gwendoline; Goslin, Jérôme; Roubi, A.; Penaud, Aurélie; Vidal, Muriel; Siano, Raffaele

doi:10.1016/j.palaeo.2021.110525

Cited by 9 publications

(7 citation statements)

References 119 publications

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“…Through deposition, the sponge silica accumulates in the sediments of the Bay and is finally buried at an average rate of 0.06 cm yr −1 (Gregoire et al 2017; Ehrhold et al 2021). Within the first centimeters of marine sediments, biogenic silica—no matter its origin—dissolves progressively until the interstitial water becomes saturated in dissolved Si, an asymptotic condition in which biogenic silica dissolution typically ceases (Rickert et al 2002; Sarmiento and Gruber 2006; Khalil et al 2007).…”

Section: Discussionmentioning

confidence: 99%

“…1a; Table 2). Present‐day sedimentation rates were estimated from radiocarbon dating of surface sediment in the cores (Gregoire et al 2017; Ehrhold et al 2021). The bottoms of the deepest areas of the Bay, on which sedimentation rates are negligible (Ehrhold et al 2016), were interpreted as null contributors to the sponge silica accumulation in the Bay ( see below).…”

Section: Methodsmentioning

confidence: 99%

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Sponge contribution to the silicon cycle of a diatom‐rich shallow bay

López‐Acosta

Maldonado

Grall

et al. 2022

Limnology & Oceanography

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In coastal systems, planktonic and benthic silicifiers compete for the pool of dissolved silicon, a nutrient required to make their skeletons. The contribution of planktonic diatoms to the silicon cycle in coastal systems is often well characterized, while that of benthic silicifiers such as sponges has rarely been quantified. Herein, silicon fluxes and stocks are quantified for the sponge fauna in the benthic communities of the Bay of Brest (France). A total of 45 siliceous sponge species living in the Bay account for a silicon standing stock of 1215 tons, while that of diatoms is only 27 tons. The silicon reservoir accumulated as sponge skeletons in the surface sediments of the Bay rises to 1775 tons, while that of diatom skeletons is only 248 tons. These comparatively large stocks of sponge silicon were estimated to cycle two orders of magnitude slower than the diatom stocks. Sponge silicon stocks need years to decades to be renewed, while diatom turnover lasts only days. Although the sponge monitoring over the last 6 yr indicates no major changes of the sponge stocks, our results do not allow us to conclude if the silicon sponge budget of the Bay is at steady state, and potential scenarios are discussed. The findings buttress the idea that sponges and diatoms play contrasting roles in the marine silicon cycle. The budgets of these two major silicon users need to be integrated and their connections revealed, if we aim to improve our understanding of the silicon cycling in coastal ecosystems.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Sponge contribution to the silicon cycle of a diatom‐rich shallow bay

López‐Acosta

Maldonado

Grall

et al. 2022

Limnology & Oceanography

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“…Between 2,900 and 2,700 cal BP, subtidal sedimentary prisms and coastal barriers recorded deep morphosedimentary changes. Sharp erosional contacts and/or sedimentary hiatuses were systematically observed in the coastal sedimentary sequences, indicating increased hydrodynamics and barrier breaching (Fernane et al, 2014;Goslin et al, 2013Goslin et al, , 2015Stéphan et al, 2015;Ehrhold et al, 2021;). After ca.…”

Section: Holocene Coastal Changesmentioning

confidence: 99%

“…The 3,000−2,500 cal BP period has long been recognized as a phase of dramatic changes for morpho-sedimentary systems along the coasts of western France. In NW Brittany, erosional surfaces and sedimentary hiatuses recorded in marine and coastal sedimentary sequences reflect enhanced hydrodynamic conditions between 3,000 and 2,500 cal BP (Fernane et al, 2014;Stéphan et al, 2015;Ehrhold et al, 2021). Contemporaneous disruptions of coastal sedimentary environments along the English Channel (Billeaud et al, 2009;Sorrel et al, 2009;Lespez et al, 2010;Tessier et al, 2012) and the Atlantic coasts of France (Pontee et al, 1998;Clavé et al, 2001;Stéphan et al, 2019c;Tastet and Pontee, 1998) as regarded as the morphogenic impact of intense storms (Pouzet al, 2018).…”

Section: Regional Comparisonmentioning

confidence: 99%

“…Furthermore, the incised morphology of the lower parts of these river valleys favoured the trapping of fluvial sediments as shown by the thickness of some Holocene deposits (Menier et al, 2006). These valleys are connected to the sea by small-size estuaries where large thicknesses of sediment were deposited during the Holocene (Jouet et al, 2003;Gregoire et al, 2017;Ehrhold et al, 2021). On the foreshore, seismic data show that the valleys extend into the subtidal domain by submarine incised-valleys partially filled by a sequence of fluvial, estuarine, and marine sedimentary deposits (e.g.…”

Section: Detritism and Fluvial Sediment Inputmentioning

confidence: 99%

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Holocene evolution of coastal dunes in western France: Regional reconstruction from archaeological and historical data

et al. 2023

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An interdisciplinary approach to Late/Final Neolithic coastal gallery graves in Brittany, Western France: The 3D structure, origin of stone material, and paleoenvironmental setting of the Kernic and Lerret monuments

et al. 2023

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This article presents an interdisciplinary study of two Late/Final Neolithic gallery graves (Kernic and Lerret) located on the orthwestern coast of Brittany (Western France). These monuments show striking similarities in terms of architectural style and geographical position. This paper aims to provide a better understanding of the construction strategy of these monuments by (i) determining the origin of the megalithic blocks using comparative petro‐structural analyses of blocks and surrounding rocks, (ii) reconstructing the coastal environment from sediment core analyses and (iii) defining the significance of these monuments in the territories from an intervisibility analysis. The study reveals marked differences between the two monuments studied. The Lerret gallery grave was erected close to a unique source of stone material on the margins of a marshland zone. In contrast, the Kernic monument, erected on the edge of an estuary, seems to have been built using a deliberate diversification of stone extraction sites. An intervisibility analysis shows a dense network of visual interconnections between a number of megalithic tombs present in the study area, where the two monuments occupy very distinct sites. The social implications of stone selection and the geographical location of Late/Final Neolithic funerary monuments are also discussed in an enlarged regional context.

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Fossil maerl beds as coastal indicators of late Holocene palaeo-environmental evolution in the Bay of Brest (Western France)

Cited by 9 publications

References 119 publications

Sponge contribution to the silicon cycle of a diatom‐rich shallow bay

Sponge contribution to the silicon cycle of a diatom‐rich shallow bay

Holocene evolution of coastal dunes in western France: Regional reconstruction from archaeological and historical data

An interdisciplinary approach to Late/Final Neolithic coastal gallery graves in Brittany, Western France: The 3D structure, origin of stone material, and paleoenvironmental setting of the Kernic and Lerret monuments

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