Large‐scale ecosystem engineering by flamingos and fiddler crabs on West‐African intertidal flats promote joint food availability

The Delta Project is in its final stage. In 1974 it was subjected to political reconsideration, but it is scheduled now for completion in 1987. The final touches are being put to the storm-surge barrier and two compartment dams that divide the Oosterschelde into three areas: one tidal, one with reduced tide, and one a freshwater lake. Compartmentalization will result in 13% of channels, 45% of intertidal flats and 59% of salt marshes being lost. There is a net gain of 7% of shallow-water areas. Human interventions with large scale impacts are not new in the Oosterschelde but the large scale and short time in which these interventions are taking place are, as is the creation of a controlled tidal system. This article focusses on the area with reduced tide and compares resent day and expected characteristics. In this reduced tidal part salt marshes will extend by 30–70%; intertidal flats will erode to a lower level and at their edges, and the area of shallow water will increase by 47%. Biomass production on the intertidal flats will decrease, with consequences for crustaceans, fishes and birds. The maximum number of waders counted on one day and the number of ‘bird-days' will decrease drastically, with negative effects for the wader populations of western Europe. The net area with a hard substratum in the reduced tidal part has more than doubled. Channels will become shallower. Detritus import will not change significantly. Stratification and oxygen depletion will be rare and local. The operation of the storm-surge barrier and the closure strategy chosen are very important for the ecosystem. Two optional closure strategies can be followed without any additional environmental consequences. It was essential to determine a clearly defined plan of action for the whole area, and to make land-use choices from the outset. How this was done is briefly described.

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Composition and abundance of shorebird and macroinvertebrate communities differ according to densities of burrowing fiddler crabs in tropical intertidal flats

Hydrobiologia ◽

10.1007/s10750-021-04601-1 ◽

2021 ◽

Author(s):

João Paulino ◽

José Pedro Granadeiro ◽

Mohamed Henriques ◽

João Belo ◽

Teresa Catry

Keyword(s):

Macroinvertebrate Communities ◽

Fiddler Crabs ◽

Intertidal Flats

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Equine-Origin Immunoglobulin Fragments Protect Nonhuman Primates from Ebola Virus Disease

Journal of Virology ◽

10.1128/jvi.01548-18 ◽

2018 ◽

Vol 93 (5) ◽

Cited By ~ 2

Author(s):

Hualei Wang ◽

Gary Wong ◽

Wenjun Zhu ◽

Shihua He ◽

Yongkun Zhao ◽

...

Keyword(s):

Large Scale ◽

Nonhuman Primates ◽

Ebola Virus ◽

Virus Disease ◽

Hemorrhagic Fever ◽

West African ◽

Clinical Testing ◽

The Past ◽

Over 40 Years

ABSTRACT Ebola virus (EBOV) infections result in aggressive hemorrhagic fever in humans, with fatality rates reaching 90% and with no licensed specific therapeutics to treat ill patients. Advances over the past 5 years have firmly established monoclonal antibody (MAb)-based products as the most promising therapeutics for treating EBOV infections, but production is costly and quantities are limited; therefore, MAbs are not the best candidates for mass use in the case of an epidemic. To address this need, we generated EBOV-specific polyclonal F(ab′)2 fragments from horses hyperimmunized with an EBOV vaccine. The F(ab′)2 was found to potently neutralize West African and Central African EBOV in vitro. Treatment of nonhuman primates (NHPs) with seven doses of 100 mg/kg F(ab′)2 beginning 3 or 5 days postinfection (dpi) resulted in a 100% survival rate. Notably, NHPs for which treatment was initiated at 5 dpi were already highly viremic, with observable signs of EBOV disease, which demonstrated that F(ab′)2 was still effective as a therapeutic agent even in symptomatic subjects. These results show that F(ab′)2 should be advanced for clinical testing in preparation for future EBOV outbreaks and epidemics. IMPORTANCE EBOV is one of the deadliest viruses to humans. It has been over 40 years since EBOV was first reported, but no cure is available. Research breakthroughs over the past 5 years have shown that MAbs constitute an effective therapy for EBOV infections. However, MAbs are expensive and difficult to produce in large amounts and therefore may only play a limited role during an epidemic. A cheaper alternative is required, especially since EBOV is endemic in several third world countries with limited medical resources. Here, we used a standard protocol to produce large amounts of antiserum F(ab′)2 fragments from horses vaccinated with an EBOV vaccine, and we tested the protectiveness in monkeys. We showed that F(ab′)2 was effective in 100% of monkeys even after the animals were visibly ill with EBOV disease. Thus, F(ab′)2 could be a very good option for large-scale treatments of patients and should be advanced to clinical testing.

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Influence of the representation of convection on the mid-Holocene West African Monsoon

Climate of the Past ◽

10.5194/cp-17-1665-2021 ◽

2021 ◽

Vol 17 (4) ◽

pp. 1665-1684

Author(s):

Leonore Jungandreas ◽

Cathy Hohenegger ◽

Martin Claussen

Keyword(s):

Land Surface ◽

Large Scale ◽

Climate Models ◽

Climate Model ◽

Monsoon Season ◽

West African Monsoon ◽

West African ◽

Global Climate Models ◽

African Monsoon ◽

Monsoonal Precipitation

Abstract. Global climate models experience difficulties in simulating the northward extension of the monsoonal precipitation over north Africa during the mid-Holocene as revealed by proxy data. A common feature of these models is that they usually operate on grids that are too coarse to explicitly resolve convection, but convection is the most essential mechanism leading to precipitation in the West African Monsoon region. Here, we investigate how the representation of tropical deep convection in the ICOsahedral Nonhydrostatic (ICON) climate model affects the meridional distribution of monsoonal precipitation during the mid-Holocene by comparing regional simulations of the summer monsoon season (July to September; JAS) with parameterized and explicitly resolved convection. In the explicitly resolved convection simulation, the more localized nature of precipitation and the absence of permanent light precipitation as compared to the parameterized convection simulation is closer to expectations. However, in the JAS mean, the parameterized convection simulation produces more precipitation and extends further north than the explicitly resolved convection simulation, especially between 12 and 17∘ N. The higher precipitation rates in the parameterized convection simulation are consistent with a stronger monsoonal circulation over land. Furthermore, the atmosphere in the parameterized convection simulation is less stably stratified and notably moister. The differences in atmospheric water vapor are the result of substantial differences in the probability distribution function of precipitation and its resulting interactions with the land surface. The parametrization of convection produces light and large-scale precipitation, keeping the soils moist and supporting the development of convection. In contrast, less frequent but locally intense precipitation events lead to high amounts of runoff in the explicitly resolved convection simulations. The stronger runoff inhibits the moistening of the soil during the monsoon season and limits the amount of water available to evaporation in the explicitly resolved convection simulation.

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Climate Models Lack Jet–Rainfall Coupling over West Africa

Journal of Climate ◽

10.1175/jcli-d-16-0579.1 ◽

2017 ◽

Vol 30 (12) ◽

pp. 4625-4632 ◽

Cited By ~ 6

Author(s):

D. Whittleston ◽

S. E. Nicholson ◽

A. Schlosser ◽

D. Entekhabi

Keyword(s):

West Africa ◽

Large Scale ◽

Climate Models ◽

West African ◽

Strongly Coupled ◽

Zonal Jets ◽

Remote Forcing ◽

African Rainfall ◽

Jet Variability ◽

West African Sahel

Changes in large-scale dynamics over West Africa—the strength and position of zonal jets—are a key interim step by which local and remote forcing is communicated into changes in rainfall. This study identifies a key mode of jet variability and demonstrates how it is strongly coupled with rainfall. The approach provides a quantitative framework to assess jet–rainfall coupling and a useful tool to investigate the concerning spread in CMIP5 rainfall projections over the West African Sahel. It is shown that many CMIP5 simulations fail to capture this coupling, indicating a fundamental limitation in their ability to predict future rainfall conditions. The results demonstrate that West African rainfall in the coming CMIP6 ensemble should be interpreted with caution; key atmospheric processes that deliver rainfall must be validated before conducting detailed analysis on rainfall.

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Internal Intraseasonal Variability of the West African Monsoon in WRF

Journal of Climate ◽

10.1175/jcli-d-16-0750.1 ◽

2017 ◽

Vol 30 (15) ◽

pp. 5815-5833 ◽

Cited By ~ 2

Author(s):

Ghassan J. Alaka ◽

Eric D. Maloney

Keyword(s):

East Africa ◽

Large Scale ◽

Intraseasonal Variability ◽

West African Monsoon ◽

West African ◽

Boreal Summer ◽

Kelvin Wave ◽

The West ◽

African Monsoon ◽

External Influences

The West African monsoon (WAM) and its landmark features, which include African easterly waves (AEWs) and the African easterly jet (AEJ), exhibit significant intraseasonal variability in boreal summer. However, the degree to which this variability is modulated by external large-scale phenomena, such as the Madden–Julian oscillation (MJO), remains unclear. The Weather Research and Forecasting (WRF) Model is employed to diagnose the importance of the MJO and other external influences for the intraseasonal variability of the WAM and associated AEW energetics by removing 30–90-day signals from initial and lateral boundary conditions in sensitivity tests. The WAM produces similar intraseasonal variability in the absence of external influences, indicating that the MJO is not critical to produce WAM variability. In control and sensitivity experiments, AEW precursor signals are similar near the AEJ entrance in East Africa. For example, an eastward extension of the AEJ increases barotropic and baroclinic energy conversions in East Africa prior to a 30–90-day maximum of perturbation kinetic energy in West Africa. The WAM appears to prefer a faster oscillation when MJO forcing is removed, suggesting that the MJO may serve as a pacemaker for intraseasonal oscillations in the WAM. WRF results show that eastward propagating intraseasonal signals (e.g., Kelvin wave fronts) are responsible for this pacing, while the role of westward propagating intraseasonal signals (e.g., MJO-induced Rossby waves) appears to be limited. Mean state biases across the simulations complicate the interpretation of results.

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Correction: Ecosystem Engineering by Plants on Wave-Exposed Intertidal Flats Is Governed by Relationships between Effect and Response Traits

PLoS ONE ◽

10.1371/journal.pone.0171364 ◽

2017 ◽

Vol 12 (1) ◽

pp. e0171364 ◽

Cited By ~ 1

Author(s):

Maike Heuner ◽

Alexandra Silinski ◽

Jonas Schoelynck ◽

Tjeerd J. Bouma ◽

Sara Puijalon ◽

...

Keyword(s):

Ecosystem Engineering ◽

Intertidal Flats ◽

Response Traits

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To court or not to court: reproductive decisions by male fiddler crabs in response to fluctuating food availability

Behavioral Ecology and Sociobiology ◽

10.1007/s00265-007-0542-8 ◽

2008 ◽

Vol 62 (7) ◽

pp. 1139-1147 ◽

Cited By ~ 16

Author(s):

Tae Won Kim ◽

Kotaro Sakamoto ◽

Yasuhisa Henmi ◽

Jae C. Choe

Keyword(s):

Food Availability ◽

Reproductive Decisions ◽

Fiddler Crabs

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Tropical Atlantic Variability Modes (1979–2002). Part I: Time-Evolving SST Modes Related to West African Rainfall

Journal of Climate ◽

10.1175/2008jcli2607.1 ◽

2008 ◽

Vol 21 (24) ◽

pp. 6457-6475 ◽

Cited By ~ 86

Author(s):

Irene Polo ◽

Belén Rodríguez-Fonseca ◽

Teresa Losada ◽

Javier García-Serrano

Keyword(s):

Large Scale ◽

Monsoon Season ◽

Rainfall Variability ◽

Principal Component ◽

West African ◽

Tropical Atlantic ◽

Kelvin Wave ◽

Sst Variability ◽

The Mediterranean ◽

Sst Anomalies

Abstract This work presents a description of the 1979–2002 tropical Atlantic (TA) SST variability modes coupled to the anomalous West African (WA) rainfall during the monsoon season. The time-evolving SST patterns, with an impact on WA rainfall variability, are analyzed using a new methodology based on maximum covariance analysis. The enhanced Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) dataset, which includes measures over the ocean, gives a complete picture of the interannual WA rainfall patterns for the Sahel dry period. The leading TA SST pattern, related to the Atlantic El Niño, is coupled to anomalous precipitation over the coast of the Gulf of Guinea, which corresponds to the second WA rainfall principal component. The thermodynamics and dynamics involved in the generation, development, and damping of this mode are studied and compared with previous works. The SST mode starts at the Angola/Benguela region and is caused by alongshore wind anomalies. It then propagates westward via Rossby waves and damps because of latent heat flux anomalies and Kelvin wave eastward propagation from an off-equatorial forcing. The second SST mode includes the Mediterranean and the Atlantic Ocean, showing how the Mediterranean SST anomalies are those that are directly associated with the Sahelian rainfall. The global signature of the TA SST patterns is analyzed, adding new insights about the Pacific–Atlantic link in relation to WA rainfall during this period. Also, this global picture suggests that the Mediterranean SST anomalies are a fingerprint of large-scale forcing. This work updates the results given by other authors, whose studies are based on different datasets dating back to the 1950s, including both the wet and the dry Sahel periods.

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