Modern palynological record in the Bay of Brest (NW France): Signal calibration for palaeo-reconstructions

Lambert, Clément; Vidal, Muriel; Penaud, Aurélie; Combourieu-Nebout, Nathalie; Lebreton, V.; Ragueneau, Olivier; Gregoire, Gwendoline

doi:10.1016/j.revpalbo.2017.04.005

Cited by 14 publications

(17 citation statements)

References 53 publications

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“…4). Also, for Alnus, Chenopodiaceae, and Poaceae, top values from the I_09 core are obviously similar to mean modern values reconstructed in the area (Lambert et al, 2017).…”

Section: Pollen Assemblagessupporting

confidence: 67%

“…We indeed observe a significant increase in amoebae concentrations (i.e. continental markers; Mitchell et al, 2008;Lambert et al, 2017). In addition, benthic foraminifera are known to strongly react to anthropogenic pollution.…”

Section: Accepted Manuscriptmentioning

confidence: 58%

“…Bahr et al, 2005;Mollier-Vogel et al, 2013;Steinke et al, 2014). A recent study carried out on Bay of Brest modern sediments leads us to consider Alnus as a fluvial discharge indicator, based on its present-day distribution, which is correlated to river mouths (Lambert et al, 2017). Its fluvial discharge significance is thus confirmed, especially since this taxon has not been found to increase on the corresponding watersheds over the last decades (National Botanical Conservatory of Brest, personal…”

Section: Major Runoff Increase Over the Last 60 Yearsmentioning

confidence: 97%

“…Major taxa (those exceeding a threshold of 2% among the whole assemblage) are depicted in (Lambert et al, 2017) in the Daoulas Bay (identified with red dots in Fig. 4).…”

Section: Pollen Assemblagesmentioning

confidence: 99%

“…over or under-representation) regarding the continental surface covered by vegetation and fossil pollen percentages calculated from modern sediment archives (e.g. Gaillard et al, 1998;Mazier et al, 2015;Ganne et al, 2016), as recently discussed for Bay of Brest watersheds versus modern sediments retrieved within the bay (Lambert et al, 2017). Furthermore, some studies highlight a large influence of climate-driven processes on the pollination rates of some trees (van Vliet et al, 2002;García-Mozo et al, 2006;Besancenot and Thibaudon, 2012), as well as on the transport of pollen grains through temporal variability of precipitation and thus river runoffs.…”

Section: Introductionmentioning

confidence: 99%

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Human-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)

Lambert

Penaud

Vidal

et al. 2018

Global and Planetary Change

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For the first time a very high resolution palynological study (mean resolution of 1 to 5 years) was carried out over the last 150 years in a French estuarine environment (Bay of Brest; NW France), allowing direct comparison between the evolution of landscapes, surface water, and human practices on Bay of Brest watersheds, through continental (especially pollen grains) and marine (phytoplanktonic microalgae: cysts of dinoflagellates or dinocysts) microfossils. Thanks to the small size of the watersheds and the close proximity of the depositional environment to the mainland, the Bay of Brest represents an ideal case study for palynological investigations. Palynological data were then compared to published palaeo-genetic analyses conducted on the same core and to various available instrumental data, allowing us to better characterize past environmental variability since the second half of the 19th century in Western Brittany. We provide evidence of some clues of recent eutrophication and/or pollution that affected phytoplankton communities and which appears linked with increased runoff (higher precipitations, higher percentages of riparian forest pollen, decline of salt marsh-type indicators, and higher values of the XRF Ti/Ca signal), mainly explained by the evolution of agricultural practices since 1945 superimposed on the warming climate trend. We assume that the significant relay observed between dinocyst taxa: Lingulodinium machaerophorum and Spiniferites bentorii around 1965 then followed by Spiniferites membranaceus after 1985, attests to a strong and recent eutrophication of Bay of Brest surface waters induced by high river runoff combined with abnormally elevated air temperatures, especially obvious in the data from 1990. The structure of the dinocyst community has thus been deeply altered, accompanied by an unprecedented increase of Alexandrium minutum toxic form at the same period, as confirmed by the genetic quantification. Despite this recent major anthropogenic forcing, the fossil pollen sequence also records natural climate variability. We highlight, for the first time, a possible connection between climate (AMO modes) and fossil pollen records (especially tree pollination rates) in coastal sediments using tree percentage fluctuations as an indirect Highlights ► High resolution palynological study (last 150 yrs) in a French estuary ► Increased runoff on mainland since 1945 ► Increased eutrophication indices since 1980 ► Changes in phytoplankton communities and increased toxic algal blooms ► Connection between AMO modes and fossil pollen records (tree pollination rates)

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“…4). Also, for Alnus, Chenopodiaceae, and Poaceae, top values from the I_09 core are obviously similar to mean modern values reconstructed in the area (Lambert et al, 2017).…”

Section: Pollen Assemblagessupporting

confidence: 67%

Section: Accepted Manuscriptmentioning

confidence: 58%

Section: Major Runoff Increase Over the Last 60 Yearsmentioning

confidence: 97%

“…Major taxa (those exceeding a threshold of 2% among the whole assemblage) are depicted in (Lambert et al, 2017) in the Daoulas Bay (identified with red dots in Fig. 4).…”

Section: Pollen Assemblagesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Human-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)

Lambert

Penaud

Vidal

et al. 2018

Global and Planetary Change

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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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Revealing anthropogenic effects on lakes and wetlands: Pollen-based environmental changes of Liangzi Lake, China over the last 150 years

Dong

Yang

2021

CATENA

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Modern palynological record in the Bay of Brest (NW France): Signal calibration for palaeo-reconstructions

Cited by 14 publications

References 53 publications

Human-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)

Human-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)

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

Revealing anthropogenic effects on lakes and wetlands: Pollen-based environmental changes of Liangzi Lake, China over the last 150 years

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