Assessing the potential risk and relationship between microplastics and phthalates in surface seawater of a heavily human-impacted metropolitan bay in northern China
The impacts of microplastics (MPs) and phthalates (PAEs), a class of MP-associated contaminants, on the marine environment are not thoroughly understood despite concern over their adverse effects on humans and ecosystems. Field studies linking MPs and PAEs in seawater have not yet been reported. We investigate for the first time the correlation between MPs contamination and the presence of PAEs in the surface seawater of Jiaozhou Bay (JZB), a semi-enclosed metropolitan bay in northern China heavily impacted by human activity. The abundance of MPs, dominated by polyethylene and polyethylene terephthalate mostly smaller than 2 mm, ranged between 24.44 items/m3 and 180.23 items/m3, with the majority being black and transparent fibers and fragments. Concentrations of PAEs varied from 129.96 ng/L to 921.22 ng/L. Relatively higher abundances of MPs and higher concentrations of PAEs were generally found in areas near riverine inputs and sewage treatment plants. There was a strong correlation between PAEs concentration and MPs abundance, suggesting that they are closely linked. In a risk assessment combining PAEs and MPs, the risk quotients (RQs) indicated that the ecological risk of di-n-butyl phthalate in JZB was relatively high (0.046 (Ecotoxicology and Environmental Safety. vol. 204, n° 0147-6513, pp. 111067, 01/11/2020) EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Circulation patterns and implication for fine sediment transport in a preserved tropical estuary: The case of the Maroni (French Guiana)
Compared to temperate estuaries, tropical ones are less documented. Among them, the numerous estuaries along the Guiana shoreline present at least two original features: they are still preserved from anthropogenic modifications, and their hydro-morphodynamics are influenced by longshore migration of outer coastal mud banks. This study deals with the Maroni estuary, a mesotidal preserved tropical estuary, currently spotting more attention to better anticipate changes related to the development of harbour activities. Field data collected over semi-diurnal tidal cycles in the lower estuary revealed the presence of a turbidity maximum and seasonally contrasted hydro-sedimentary features. A one-year 3D hydrodynamic simulation covering a wide-range of tidal and fluvial conditions was performed to further analyse the seasonal variability of stratification and residual circulation patterns. The estuary is wellmixed for a very low river discharge (lower than 200 m 3 /s). It becomes partly mixed in both spring and neap tide in case of a moderate river discharge of 700 m 3 /s. The strongest stratification, which could be associated to a salt wedge near the mouth, appears during neap tides combined with higher discharge. Residual currents along the navigation channel are usually seaward except during neap tides when the discharge is large enough (700 m 3 /s) to generate stratification and landward residual current near the bottom to mid depth until the first km 15 from the mouth. Residual inflow starts from the location of the mud bank and extends along the navigation channel near the eastern bank. The inflow extension matches with observed highly turbid areas and fresh mud deposits, suggesting an outer supply of mud. In summary, this exploratory work allows a first description of current dynamics of the Maroni, and is a first step before a comprehensive study of changes in estuarine circulation and fine sediment transport under different configurations of coastal mud banks.
(Regional Studies in Marine Science. vol. 40, n° 2352-4855, pp. 101493, 01/11/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEEISA, IFREMER, UG, CNRS
Modelling of embayed beach equilibrium planform and rotation signal
9 Embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries, which 10 deeply affect equilibrium beach planform and shoreline dynamics. We use LX-Shore, a state-of-the-art 11 shoreline change model coupled with a spectral wave model to address embayed beach shoreline 12 dynamics driven by longshore sediment transport processes. The model is applied to different 13 idealized embayed beach configurations including variations in headland lengths. The model simulates 14 a large range of equilibrium embayed beach planforms and associated spatial and temporal modes of 15 shoreline variability. For short headlands enabling occasional headland sand bypassing, both embayed 16 beach curvature and maximum erosion at the upwave side of the embayment increases with increasing 17 headland length. Beach curvature also increases with increasing headland length for headlands long 18 enough to prevent any headland sand bypassing. In contrast, at the same time, embayed beach 19 becomes increasingly curved and symmetric, with maximum localised erosion within the embayment 20 decreasing in intensity. When there is no headland sand bypassing, rotation signal decreases in 21 amplitude and becomes increasingly symmetric with increasing headland length. The modal (time-22 invariant) directional spreading of incident waves is critical to embayed beach behaviour, with the 23 envelope and variance of cross-shore shoreline change and time-averaged shoreline curvature all 24 increasing with decreasing modal directional spreading. Embayed beach rotation characteristic 25 timescale increases with increasing embayed beach length, while the narrower the embayment the 26 smaller the cross-shore amplitude of shoreline variability. Our simulations provide new insight into the 27 influence of embayment characteristics and incident wave conditions on equilibrium planform and 28 shoreline dynamics of embayed beaches. This work also implies that the degree of potential headland 29 sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed 30 beach dynamic planform configuration. 31 Highlights 32 • Embayed beach shoreline response is simulated with a hybrid shoreline model 33 • Headland length and headland sediment bypassing control shoreline response 34 • Wave directional spreading is critical to both mean shoreline and rotation signal 35 • Embayment beach length controls rotation characteristic timescale 36 37 Keywords: embayed beach ; hybrid shoreline model ; headland length ; rotation ; equilibrium 38 beach planform; headland sand bypassing 39 40
(Geomorphology. vol. 369, n° 0169-555X, pp. 107367, 01/11/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
The 3rd workshop on sediment dynamics of muddy coasts and estuaries: An introduction and synthesis
The workshop series on sediment dynamics of muddy coasts and estuaries focuses on international frontier issues and major social needs, such as land-sea interactions, estuarine and coastal monitoring, numerical simulation, sediment transport and its biogeochemical effects. The Third Workshop was held in Qingdao, China, in November 2018, hosted by the Institute of Estuarine and Coastal Studies, Ocean University of China. As a result of the Third Workshop, this special issue contains 18 papers with case studies of muddy coasts in the Bohai, Yellow and East China Seas in China and other regions worldwide. These papers represent the most recent advances in Chinese and international estuarine and coastal sediment research in the topics including 1) In-situ observations of sediment dynamics in muddy coasts and estuaries and satellite remote sensing; 2) Modelling of sediment transport and associated sedimentary processes; 3) Fluid mud transport and process in bottom boundary layer, and 4) Blue bay remediation action plan and coastal restoration.
(Estuarine, Coastal and Shelf Science. vol. 245, n° 0272-7714, pp. 106994, 30/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Parasite Assemblages in a Bivalve Host Associated with Changes in Hydrodynamics
Studies on marine community structure and their modulation by horizontal and vertical abiotic gradients have focused on free-living species, neglecting parasites despite their important role in ecosystems. Field observations, a laboratory flume experiment and modelling were used to examine parasite infection patterns related to host tidal and spatial position along a Portuguese coastal lagoon (Ria de Aveiro). Cockles (Cerastoderma edule) and trematodes were used as a host-parasite model to test the hypotheses: (1) higher infection levels in subtidal cockles, positioned downstream and (2) higher current velocity in downstream areas with consequent higher cockle infection. Cockles were collected from two spatial and tidal positions in two seasons. The relationship between current velocity and cockle infection was examined experimentally by exposing cockles to cercariae of Himasthla elongata at two current velocities. Intertidal cockles displayed higher infection, highlighting vertical position as an important driver of infection possibly due to first host proximity and/or trematode life cycle facilitation (higher cockle exposure to final host predation). The hydrodynamic model showed that the Ria de Aveiro was abiotically heterogenous with cockles displaying higher infection levels in the downstream area. Multiple regression analysis demonstrated a positive correlation between salinity, dissolved oxygen, current velocity and trematode abundance. The influence of current velocity on infection success was corroborated experimentally. The present study demonstrated the importance of host vertical and horizontal position on trematode infection, highlighting the positive influence of current velocity by supporting settlement and promoting favourable abiotic conditions.
(Estuaries and Coasts, n° 1559-2723, 25/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Influence of Seasonal River Discharge on Tidal Propagation in the Ganges‐Brahmaputra‐Meghna Delta, Bangladesh
Significant research efforts have been devoted to understanding river-tide interactions in estuaries. However, studies on the impact of monsoon-driven fluctuations of river discharge are limited. Here, the role of varying river discharge on the tidal propagation and tidal limit along the Ganges-Brahmaputra-Meghna Delta (GBMD), a macrotidal estuary subject to seasonal and annual river discharge variations, is investigated. The Delft3D hydrodynamic model is validated and applied to an average flood year condition and nine idealized scenarios covering the typical hydrological conditions. Results reveal that the upper limit of the tidal propagation shifts 75 km upstream during the dry season. The residual water level slope and tidal damping rate increase with river discharge beyond 100 km from the estuary mouth. The balance between the generation and dissipation of quarterdiurnal tides shifts spatially as a result of changes in channel convergence and friction and temporally as a function of river discharge, which controls the total friction in the upper tidal river. The balance between tidal dissipation and generation depends on the residual velocity generated by river discharge and the velocity of the principal tides. The maximal generation of quarterdiurnal tides in the upper GBMD depends on the friction generated from the river-tide interaction. Critical river discharge thresholds produce an optimal condition of dissipation of semidiurnal tides and generation of quarterdiurnal tides through friction at the upper and middle estuary. River discharge above the critical river discharge amount more rapidly dissipates both semidiurnal and quarterdiurnal tides than generates quarterdiurnal tides from nonlinear interactions.
(Journal of Geophysical Research. Oceans. vol. 125, n° 2169-9275, pp. e2020JC016417, 12/10/2020)
UNSW, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sandy beaches can survive sea-level rise
(Nature Climate Change, n° 1758-678X, 08/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE
Cardiovascular and Renal Outcomes with Empagliflozin in Heart Failure
Background: Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of hospitalization for heart failure in patients regardless of the presence or absence of diabetes. More evidence is needed regarding the effects of these drugs in patients across the broad spectrum of heart failure, including those with a markedly reduced ejection fraction. Methods: In this double-blind trial, we randomly assigned 3730 patients with class II, III, or IV heart failure and an ejection fraction of 40% or less to receive empagliflozin (10 mg once daily) or placebo, in addition to recommended therapy. The primary outcome was a composite of cardiovascular death or hospitalization for worsening heart failure. Results: During a median of 16 months, a primary outcome event occurred in 361 of 1863 patients (19.4%) in the empagliflozin group and in 462 of 1867 patients (24.7%) in the placebo group (hazard ratio for cardiovascular death or hospitalization for heart failure, 0.75; 95% confidence interval [CI], 0.65 to 0.86; P<0.001). The effect of empagliflozin on the primary outcome was consistent in patients regardless of the presence or absence of diabetes. The total number of hospitalizations for heart failure was lower in the empagliflozin group than in the placebo group (hazard ratio, 0.70; 95% CI, 0.58 to 0.85; P<0.001). The annual rate of decline in the estimated glomerular filtration rate was slower in the empagliflozin group than in the placebo group (-0.55 vs. -2.28 ml per minute per 1.73 m2 of body-surface area per year, P<0.001), and empagliflozin-treated patients had a lower risk of serious renal outcomes. Uncomplicated genital tract infection was reported more frequently with empagliflozin. Conclusions: Among patients receiving recommended therapy for heart failure, those in the empagliflozin group had a lower risk of cardiovascular death or hospitalization for heart failure than those in the placebo group, regardless of the presence or absence of diabetes. (Funded by Boehringer Ingelheim and Eli Lilly; EMPEROR-Reduced ClinicalTrials.gov number, NCT03057977.).
(New England Journal of Medicine. vol. 383, n° 0028-4793, pp. 1413-1424, 08/10/2020)
BUMC, UMMC, NKUA, LSHTM, UNSW, USP, SNU, MUHC, UZ Leuven, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CHUS, MUMC, CMU, BHF GCRC, NHSGGC, Hosp P Giovanni XXIII, CHRU Besançon, UniPi, DCAC, CHRU Nancy, INSERM, UL, CIC-P, CIC, CHRU Nancy, INSERM, UL, INI-CRCT, Cardiovascular & Renal Clinical Trialists - CRCT
A Regional Assessment of Changes in Plant–Plant Interactions Along Topography Gradients in Tunisian Sebkhas
Facilitation among plants in dry ecosystems is crucial for diversity and ecosystem functioning and stability. However, the importance of facilitation in extremely stressful conditions is highly debated. We attempt to separate the effects of direct non-resource and resource stress factors on plant–plant interactions by assessing changes in facilitation and competition along salinity gradients at two contrasting levels of aridity. We selected eight saline depressions (hereafter sebkhas) in the wet and dry Mediterranean arid climate of North Africa, from central Tunisia to the Libyan border 500 km south-eastward. In each sebkha, we transplanted at four positions along the salinity gradient induced by topography, both in open areas and below dominant shrubs, three target species with contrasting tolerances to salinity stress. Target plant survival, soil electrical conductivity and moisture were recorded before and after the dry summer season in all treatments. Shrubs decreased salinity and drought stresses in all treatments, and facilitation was the dominant interaction. However, we found a strong collapse of facilitation along the salinity gradient, due to a dramatic mortality of the three target species both with and without neighbours above their threshold of salinity tolerance. Increasing aridity induced an earlier collapse of facilitation along the gradient. The three target species had contrasting responses to neighbours, with the least stress-tolerant species being facilitated and the two most stress-tolerant ones negatively affected by neighbours. Our study shows that disentangling resource and non-resource stresses along gradients and controlling for target species effects help understanding variation in plant–plant interactions under highly stressful conditions. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.
(Ecosystems. vol. 24, n° 1432-9840, pp. 1024-1037, 06/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
How costly are metacercarial infections in a bivalve host? Effects of two trematode species on biochemical performance of cockles
Bivalve stocks have been decreasing in the last decades largely due to emergent diseases and consequent mass mortality episodes. Cerastoderma edule (the edible cockle) is one of the most exploited bivalves in Europe and is among the most common hosts for trematodes, the most prevalent macroparasites in coastal waters but yet poorly studied. Therefore, in the present study, this bivalve species was used as host model to determine if trematode infection exerts a negative effect on bivalve energy metabolism and balance and if the tissues targeted by different trematodes influence the metabolic cost, with physiological and biochemical consequences. Cockles were experimentally infected with two trematode species, Himasthla elongata and Renicola roscovitus, that infect the foot and palps, respectively. Trematode infection exerted a negative effect on the metabolism of C. edule, the second intermediate host, by reduction of oxygen consumption. A different host biochemical response was found depending on trematode species, especially in regard to the level of oxygen consumption decrease and the preferential accumulation of lipids and glycogen. This study represents a step towards the understanding of host-trematode relationships that can be used to better predict potential conservation threats to bivalve populations and to maximize the success of stock and disease management.
(Journal of Invertebrate Pathology, n° 0022-2011, pp. 107479, 01/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS