Temporary Ponds Research Articles

Environment and Space Rule, but Time Also Matters for the Organization of Tropical Pond Metacommunities

Metacommunities are dynamic systems, but the influence of time independently of environmental change in their configuration has been rarely considered. Temporary ponds are excellent ecosystem models, as they have well-defined boundaries in time and space; their communities are relatively isolated through a landscape matrix, and the progress of time leads to major changes through ecological succession and in habitat suitability related to hydroperiod dynamics. Therefore, strong temporal effects are expected to influence their metacommunity structure. We surveyed 30 temporary ponds along the dry tropical region of western Costa Rica and Nicaragua at three different moments of their hydroperiod: shortly after the infilling of the water bodies, at the middle of the hydroperiod and just before desiccation. We obtained data on 56 environmental variables (including limnological, climatic, landscape, hydrogeomorphological and conservation state), and used geographic coordinates to build spatial variables (Moran Eigenvector Maps). We collected biological samples and estimated the specific abundance of phytoplankton, zooplankton and benthic invertebrates. To evaluate the relative role of environmental, spatial and temporal (sequential sampling season) effects in metacommunity organization of the 646 species found, we used variation partitioning with distance-based redundancy analyses for each group of organisms. We repeated the analyses for selected taxonomic groups, separately for each sampling season, to check how the variance explained by spatial and environmental factors varied between sampling periods. The inclusion of time in the analysis highlighted that pure temporal effects explained part of metacommunity variance in almost every group, being as important as spatial or even environmental effects for some groups of organisms. In contrast to the assumed low environmental constraints in tropical areas (i.e. high and stable temperatures), we found strong environmental effects. Passive dispersers were more influenced by environmental factors than active ones. We also found a positive relationship between the body size of the different groups of organism and the magnitude of the temporal effect, interpreted as related to generation time. Finally, when analyzing each sampling period separately, we found differences in the relative role of environment and space at different sampling periods, showing that snapshot surveys may not be representative of highly dynamic metacommunities.

Herpetofauna of the Environmental Protection Area Delta do Parnaíba, Northeastern Brazil

Recent studies on Brazilian coastal zones and restinga environments revealed a high richness ofamphibian and reptile species. However, there is still a lack of information about herpetofaunadiversity in coastal zones of Northeastern Brazil. This study provides a checklist of amphibiansand reptiles inhabiting the Environmental Protection Area (EPA) Delta do Parnaiba, NortheasternBrazil, suggesting conservation actions. To elaborate the checklist, we searched in sevenelectronic databases and check the following scientific collections: Zoological collection ofUniversidade Federal do Piaui (UFPI) and Herpetological collection of Universidade Regionaldo Cariri (URCA). In addition, we sampled 16 areas along the EPA Delta do Parnaiba close tothe river branches and temporary ponds that compose the Parnaiba River Delta (December 2015to April 2017) to fill gaps of information about herpetofauna in some regions from the EPA. Werecorded 86 species (34 amphibians and 52 reptiles), including four anurans, one crocodilian,14 snakes, 12 lizards and two amphisbaenians reported for the first time for the EPA Delta doParnaiba. In addition, we added the first record of the snake Oxybelis fulgidus in Piaui state. TheEPA Delta do Parnaiba shows high herpetofaunal richness; thus, we suggest that conservationactions should be taken to preserve the restingas environments in the Parnaiba River Delta andits high diversity of amphibians and reptiles.

Aquatic beetles influence colonization of disparate taxa in small lentic systems.

Structure of natural communities is shaped by both abiotic characteristics and the ongoing processes of community assembly. Important to this process are the habitat selection behaviors and subsequent survival of colonists, both in the context of temporal changes in the abiotic characteristics and priority effects driven by earlier colonists. Aquatic beetles are prevalent in temporary freshwater systems, form speciose assemblages, and are often early colonists of temporary ponds. While beetles have the potential to influence community structure through post‐colonization interactions (predation and competition), our goal was to determine whether the presence of beetle assemblages (versus patches without beetles) influences the colonization and oviposition of a diverse group of animals in a naturally colonized experimental landscape. We established mesocosms that either contained existing beetle assemblages or contained no beetles and assessed abundances of subsequent colonists. Treefrogs, Hyla chrysoscelis, and mosquitoes, Culex restuans, both deposited fewer eggs in patches containing beetle assemblages, while two beetles, Copelatus glyphicus and Paracymus, colonized those patches at lower rates. One beetle, Helophorus linearis, colonized patches containing beetle assemblages at higher rates, while two beetles, Berosus infuscatus and Tropisternus lateralis, exhibited no colonization differences between treatments. Overall, there were no differences in the assemblage structure or richness of beetles that colonized patches. Our results illustrate the importance of species‐specific habitat selection behavior in determining the species composition of habitat patches, while emphasizing the role of priority effects in influencing patterns of community assembly. Habitat selection in response to abiotic and biotic characteristics of habitat patches can potentially create greater spatiotemporal niche separation among the numerous, often closely related species (phylogenetically and trophically), that can be simultaneously found in similar patches across landscapes.

Refining the activity level-predation risk paradigm in larval anuran communities

The activity level-predation risk paradigm of community assembly is based on observable trade-offs between activity level and predation risk. Many species that live in ephemeral habitats are relatively more active, grow faster, and metamorphose sooner than those in more permanent habitats, thus enabling them to survive by escaping drying ponds. Species with high activity levels are shown to be superior competitors in temporary ponds, but are at greater risk of predation by visually cued predators. We take a comprehensive approach to testing if the activity-predation paradigm drives community assembly of a four-species guild of larval anurans through field surveys and a series of laboratory experiments quantifying their activity level, anti-predatory responses, swim performance, and escape behavior. Activity level was a good predictor of susceptibility to predation and habitat association for most species in our study, but not all species fit the pattern. Secondary anti-predator mechanisms contributed to differences in susceptibility to predation. Some species were more capable of avoiding predation through swim performance and escape behavior, thus allowing them to occupy a greater range of the water permanency continuum than was predicted by activity level alone. Because performance traits are deeply rooted, evolutionary history plays a major role in determining tadpole performance and life-history traits. Whole-organism performance traits (e.g., swim performance, escape behavior) have not generally been considered in the classic activity-predation paradigm. Our results show that accounting for individual and species-level performance reveals the understudied, yet important role of species-specific performance traits in disentangling the mechanisms driving community assembly.

Physicochemical Characteristics of the Okomu Wetland, Edo State, Nigeria

Water quality assessment was carried out within the 202 km2 Okomu National Park located within the 1,082km2Okomu Forest Reserve between January 2017 and December 2018. Water sampling was carried in ten compartments of approximately 1.6km2 each, covering Ponds, Stream and River, based on easy accessibility. No such study has been carried out for the Okomu Wetlands in the past three decades. Sampling protocols, laboratory analysis and quality control/quality assurance measures followed standard procedures. All physicochemical parameters showed significant (P < 0.001) spatial variations. The maximum and minimum values obtained for physicochemical parameters of the Okomu Wetland are 23.6 and 38.0°C air temperature; 21.0 – 38°C water temperature; 0.15 – 1.02m water level; 16.7 – 150.7mg/l total dissolved Solids (TDS); 0.5 – 18.8mg/l total suspended Solids (TSS); 0.2 – 14.8mg/l turbidity; 40. 0 – 307.4µS/cm electrical conductivity (EC); 4.4 – 6.7 pH; 0.02 – 0.14mg/l salinity; 0.7 – 5.5mg/l dissolve oxygen (DO); 0.5 – 3.8mg/l biochemical oxygen demand (BOD); 1.5 – 120.2mg/l chemical oxygen demand (COD); 23.8 – 593.6mg/l bicarbonates (HCO3); 69.9 – 245.3mg/l Chlorine (Cl); 0.02 – 0.59mg/l nitrite (NO2); 0.11 – 2.34mg/l nitrate (NO3); 0.04 – 2.11mg/l ammonium-nitrogen (NH4N); 0.05 – 2.96mg/l sulphate (SO4); 0.09 – 9.2mg/l phosphorus (P); 0.20 – 2.72mg/l sodium (Na), 0.03 – 1.32mg/l potassium (K); 0.88 – 5.88mg/l calcium (Ca); 0.13 – 3.1mg/l magnesium (Mg); 5.8 – 18.9mg/l iron (Fe); 0.04 – 1.1mg/l manganese (Mn); 0.02 – 0.09mg/l copper (Cu); 0.93 – 6.0mg/l zinc (Zn); 0.01 – 2.9mg/l lead (Pb); 0.01 – 0.18mg/l cadmium (Cd); 0.06 – 4.0mg/l chromium (Cr); 0.01 – 0.15mg/l nickel (Ni); 0.01 – 11mg/l vanadium (V). Air and water temperatures were mostly influenced by forest canopy cover. pH levels indicate that the water bodies within the forested wetland are slightly acidic. Higher DO values were recorded in the Arhakhuan Stream and Okomu River (Agekpukpu and Iron bridge) than in the temporary ponds. BOD levels of greater than 1mg/l were observed which is indicative of slight levels of organic pollution. Higher concentrations of TDS, TSS, turbidity, EC, Colour, HCO3, NH4N, NO2, NO3, P, Na, K, Ca Mg and heavy metals were recorded in the temporary ponds than in the Stream and River. Research on water bodies within wetlands should be carried out routinely in order to monitor changes in the water conditions that could occur overtime whether natural or anthropogenic. This becomes even more pertinent in the light of glaring impacts of climate change and increasing environmental modifications.

Temnocephalan epibionts (Platyhelminthes, Temnocephalida) on mollusks from Pantanal wetland, Brazil.

Temnocephala iheringi Haswell, 1893 was recorded in Marisa planogyra Pilsbry, 1933 and Pomacea maculata Perry, 1810. Also, Temnocephala amatoi sp. nov. was described from Pomacea scalaris (d'Orbigny, 1835). The mollusks were collected from temporary ponds at Ypiranga Farm, Poconé, Mato Grosso, Brazil. The new species differs from six other species of Temnocephala Blanchard, 1849 epibionts on molluks by having the following combination of characters: 1. a short and curved cirrus; 2. a narrow introvert with approximately 22 longitudinal rows of spines with 13 spines each; 3. internal spines with a narrow base, longer on the base of the introvert and smaller in the distal portion; 4. a single and asymmetrical vaginal sphincter and; 5. elliptical, longer than wide epidermal 'excretory' syncytial plates (EPs) with a excretory pore displaced to the anterior portion of the plate. Temnocephala lamothei Damborenea Brusa, 2008 has a curved cirrus, similar in size to the new species' cirrus. However, the introvert is not swollen with an oblique proximal margin, marked with a thickened oblique ring and two rows of 45-50 thin spines, differentiating the species from T. amatoi sp. nov.. When comparing the specimens of T. iheringi from Poconé with the redescription of the species from Southern Brazil previously published by the authors, we found significant intraspecific variation in the size of the adhesive disk, pharynx length, shaft and introvert length, spines of the introvert length, as well as differences in the number of paranephrocytes. The size of the EPs and, when comparing with published data from Uruguayan and Argentinean specimens, the body size also showed important differences. We hypothesize that the host species may be the cause of the intraspecific variations found. Overall, the record of two new hosts for T. iheringi, the intraspecific variation found in this species and its geographical distribution being expanded 418 km further to the north, together with the description of a new species, add acknowledgment to the Rhabdocoela fauna in the Brazilian Pantanal.

Novel host report for Catadiscus uruguayensis Freitas & Lent, 1939 (Trematoda, Diplodiscidae) infecting Austrolebias Costa, 1998 species from Uruguay

The genus Catadiscus Cohn, 1904 has a total of 16 known species that infect the intestinal tract of reptiles, amphibians, and mollusks. However, Catadiscus has never been found in teleosts. The annual fish Austrolebias prognathus (Amato, 1986) and A. cheradophilus (Vaz-Ferreira, Sierra de Soriano & Scaglia de Paulete, 1965) were collected from temporary ponds in the southeast of Uruguay. The specimens found in the intestinal tract of these hosts were morphologically identified as Catadiscus uruguayensis Freitas & Lent, 1939, which until now were only known to infect amphibians. This work represents the first report of the genus Catadiscus infecting and developing in a fish host.

Temporal Evolution of Diatoms in a Temporary Pond Situated in the Massif du Sancy Mountains (Massif Central, France) and Description of a New Pinnularia Species

A floristic survey was performed on a temporary pond, “Laqui du Seignavoux”, situated in the Mont-Dore massif of the French Massif Central, between 2017 and 2019. Except in 2017, each year, we performed four sampling campaigns from April/May to December. Water samples and diatoms were collected. The temporary pond evolved from a poorly mineralized ecosystem due to snow, inducing oligotrophic and oligosaprobic water, well oxygenated in spring, to a more mineralized, less oxygenated, eutrophic–hypereutrophic, and polysaprobic environment in summer. This change in abiotic conditions was found to be linked to the presence of cattle, beginning in May, that trample and excrete in the pond, leading to higher ammonium and nitrate concentrations. During this period, the dominant species were Pinnularia sp., Nitzschia palea, and Nitzschia palea var. tenuirostris. In spring and winter, different species of Eunotia dominated the community such as Eunotia pseudogroenlandica. Finally, light microscopy (LM) and scanning electron microscopy (SEM) observations on a new species of the genus Pinnularia from the temporary pond are presented and the ecological preferences are discussed.

Large- and small-regional-scale variables interact in the dispersal patterns of aquatic macroinvertebrates from temporary ponds

Dispersal is one of the main determinants of metacommunity assembly, yet its interaction with the landscape network structure has not been fully elucidated. Large-scale regional factors such as the centrality–isolation gradient influence community abundance and richness, but small-scale regional factors, such as the direction or the distance among water bodies, might also influence them. Furthermore, the specific dispersal ability of each of the taxa will also determine this interaction. All these drivers are generally difficult to analyse together, but mesocosms usage combined with network analysis can help disentangle their relevance. We used these approaches to analyse how large and small regional factors influence dispersal dynamics. We set up several mesocosms around two source ponds with divergent locations within the network centrality–isolation gradient, at different distances and in different directions. We analysed macroinvertebrates composition and temporal trends throughout the hydroperiod considering the two regional factors: large (centrality–isolation gradient) and small (distance or direction separately) and dispersal ability (i.e. weak or strong). The large scale, being central or isolated, determined abundance and richness across the hydroperiod, with greater values in central locations. However, small regional factors, especially direction, modulated this trend making it similar to the central locations. Contrastingly, the small regional scales did not affect community composition, which differed along the large scale. Our results suggest that centrality–isolation plays a marked role in assembly processes favouring greater dispersal in central locations. However, this general pattern can be modulated by smaller regional factors and by intrinsic taxa dispersal ability, something that must be accounted within the metacommunity framework.

<p><strong>A new species from the temporary ponds of southwest Portugal: <em>Helosciadium milfontinum</em></strong></p>

The genus Helosciadium has six species of which three have been identified in Portugal: H. nodiflorum, frequent and abundant in much of the territory, and H. inundatum and H. repens, with a scattered distribution in Portugal. In the present study, a new species, Helosciadium milfontinum, a seriously threatened plant endemic, rare and scarce that grows in the temporary ponds of the Vicentinan Coastal District is described and illustrated. Morphological characters and molecular analysis of nuclear internal transcribed spacers (ITS) and plastid regions (matK, rps16-trnK and trnL-F) confirm the existence of this new taxon. Conservation status and taxonomic relationships of the new species are examined.

Influence of restoration age on egg bank richness and composition: an ex situ experiment

AbstractZooplankton community assembly after flooding in temporary ponds depends mostly on abundance and diversity of the dormant propagule bank. However, our understanding of the hatching patterns of zooplankton is imperfect. We performed an ex situ experiment to study the species composition and temporal sequence of zooplankton emergence from sediments in three ponds that were restored at different times: 1998, 2003 and 2007. The patterns of species hatching observed in our microcosms were compared with the emergent zooplankton community of their equivalent, synchronically inundated ponds. An escalation in species richness and a delay in hatching time were detected with increasing restoration age. In addition, some discrepancies between the egg bank and active populations were observed, especially in the oldest pond. This study illustrates the use of hatching experiments in comparing ponds with different characteristics. Nevertheless, egg bank hatching and water column sampling should complement each other in order to afford a full reflection of past diversity and contribute to a better understanding of the efficiency of restoration practices.

Bacteria from tropical semiarid temporary ponds promote maize growth under hydric stress

World climate change has triggered soil water stress and imposed limitations on agricultural production. Plant growth-promoting bacteria (PGPBs) have been an efficient strategy to improve the biological supply and growth of plants under distinct abiotic stress conditions. We hypothesized that the soils from a temporary pond may harbor PGPBs with potential strains which increase maize tolerance to water deficit. We studied rhizosphere and bulk soil of Mimosa bimucronata in a temporary pond from semiarid Northeast Brazil to access strains with characteristics to promote plant growth and mitigate abiotic stress for maize crop. We isolated 355 bacterial isolates, from which 96 were selected based on the morphophysiological characterization to assess IAA production (42 % produced over 50 μg mL-1 of IAA), calcium phosphate solubilization (with one isolate achieving medium IS), biofilm and exopolysaccharides production (66 % and 98 % of isolates, respectively). Based on these mechanisms, the 30 most promising bacterial isolates were selected to assess biological nitrogen fixation (74 % of the isolates showed nitrogenase activity greater than 20 C2H4.h-1.mg-1), ACC deaminase activity (80 % of isolates) and growth in medium with reduced water activity (8 % of isolates grew in medium with water activity (Aw) of 0.844). We sequenced the 16S rRNA gene from the seven most promising isolates in in vitro and in vivo assays, which were identified as Staphylococcus edaphicus, Bacillus wiedmannii, Micrococcus yunnanensis, Streptomyces alboflavus, Streptomyces alboflavus, Bacillus wiedmanni and Bacillus cereus. In vivo, eleven isolates and three bacterial consortia did not differ from the control with nutrient solution, for total leaf area and root dry mass of maize. S. alboflavus (BS43) had the best in vivo results, not differing from the control with nutrient solution. We highlight the unpublished potential of Staphylococcus edaphicus and Streptomyces alboflavus in promoting the growth of plants under water stress. In addition, it is the first report of bacteria isolated from a temporary pond in the Brazilian semiarid which promoting plant growth attributes and development.

On the Occurrence of Metadiaptomus chevreuxi (Calanoida, Diaptomidae, Paradiaptominae) in the Iberian Peninsula, With Notes on the Ecology and Distribution of its European Populations

Temporary ponds are one of the most peculiar ecosystems in the world, being characterized by an extraordinarily rich crustacean fauna, with a high degree of endemism. Among them, diaptomid copepods are among the most biogeographically interesting taxa. However, the present knowledge on diaptomid distribution is still far from being exhaustive, even in the relatively well-studied western European countries. In this study, we report the first record of the diaptomid calanoid copepod Metadiaptomus chevreuxi for the Iberian Peninsula, where it was collected in five temporary ponds in Andalusia (Spain). The characteristics of the new sites are described, the literature dealing with the European localities of the species is reviewed, and a molecular phylogenetic tree has been built, based on new and previously available mitochondrial DNA sequences, thus expanding the knowledge on the ecology and phylogeography of this rare species. The species mainly occupies small isolated temporary ponds in (semi-)arid regions, suggesting adaptations to unpredictable aquatic habitats. The existence of two molecular clades separating the Iberian from the Sicilian and Tunisian populations supports the existence of a longitudinal long-term disjunction, whereas the north-south flow is probably facilitated by migrating birds. Further research on the biota of the small water bodies of the western Mediterranean area may help to expand our knowledge on rare aquatic species, such as M. chevreuxi, and to better interpret their natural history.

Developing a Methodological Framework for Estimating Temporary Drainage Capacity to Inform Land Requirements for a Highway Construction Project in Scotland

Silt pollution generated during major highway construction projects can prove detrimental to the water environment and the aquatic species that depend on it. Construction activities can leave many kilometers of exposed soil susceptible to erosion from surface water runoff, which can result in silt pollution and degradation of ecologically sensitive watercourses if appropriate mitigation is not in place. In Scotland, assurances need to be provided during scheme development to demonstrate that there is sufficient space to accommodate temporary drainage. In response, a methodological framework has been developed that can be applied before construction commences to estimate the required capacity of settlement ponds including runoff and soil loss volume estimation, which are estimated using the Rational Method and Revised Universal Soil Loss Equation (RUSLE). The application of the framework as a case-study has demonstrated the potential applicability of the approach and highlighted where further refinements can be made to increase the robustness for future applications by improving the accuracy of input parameters to address site-specific conditions. Furthermore, it demonstrates how adopting erosion control measures can reduce the land required to accommodate temporary settlement ponds.

Influence of Anthropic and Topographic Factors on the Physicochemical Properties of the Soil around Temporary Pools in Ferlo, North Senegal

The temporary ponds at Ferlo constitute wetlands whose pastoral activity is of paramount importance in the economy of Senegal. These zones are characterized by a fairly specific microclimate (soft and humid), a shallow depth of the water table, alternating phases of submersion and exudation whose functioning is linked to the soil. Thus the restoration and conservation of these wetlands requires a good knowledge of the soil factors.
 The objective of this study is to compare the physico-chemical parameters of the soil around temporary pools in grazed and ungrazed areas and different topographical units in order to determine their relative similarities.
 The samples taken at different horizons from seven soil pits (P1, P2, P3, P4, P5, P6 and P7) opened in the different morpho-pedological facies of two grazed ponds and one ungrazed pond were analyzed in the laboratory.
 The results obtained show that the soils of Ferlo have a sandy texture and low fertility in the slopes and plateaus. However, they have a balanced texture and average fertility in ponds and ungrazed areas. The factorial analysis made it possible to highlight three distinct soil classes. A class of sandy texture soil with very low chemical fertility comes from the plateau. A class of soil with a balanced texture which is rich in cation and calcium exchange capacity found in the low zones of strong mineralization. A last class rich in chemical element with a silty texture which is found in wooded areas.
 These results thus reveal the predominant influence of anthropic and topographic factors on the evolution and physico-chemical composition of the soil.

Addressing trait selection patterns in temporary ponds in response to wildfire disturbance and seasonal succession.

Mediterranean ecosystems are increasingly threatened by disturbances such as wildfires. These disturbances are expected to shift the selective pressures that determine trait-dependent community assembly. In addition, the stochasticity in species assembly may decrease because of the introduction of strong selection regimes or may increase because of random variation in recruitment. However, these changes in the selection profile and stochasticity in disturbed communities have seldom been evaluated. We examined the relative roles of wildfire disturbance, local conditions and successional dynamics on the assembly of aquatic macroinvertebrate communities. We used the theory of community assembly by trait selection (CATS) to identify traits under selection and to estimate their dependence on wildfire disturbance and environmental gradients. We took advantage of a natural wildfire that partially burned a Mediterranean system of temporary ponds, which were surveyed before and after the wildfire, creating a natural before-after-control-impact design. Before the wildfire, the burned and unburned ponds did not show differences in the selected traits. After the wildfire event, species with larger body sizes and scrapers were favoured in the burned ponds, while collectors and active dispersers were underrepresented. Nonetheless, local environmental conditions and successional dynamics had greater relevance in the selection of traits than the wildfire. This suggests that assembly mechanisms were largely determined by seasonal successional changes regardless of wildfire disturbance. Finally, the relevance of the analysed traits diminished during the hydroperiod, suggesting more stochastic assemblages and/or a replacement in the set of selected traits. Despite the prominent role of seasonal succession over wildfire, this disturbance was associated with a change in the selection strength over specific traits related with feeding strategies and species life histories. Both hydroperiod and wildfire highlighted a strong role of trait-mediated processes (i.e. niche assembly). Therefore, the predicted increase in the frequency and intensity of wildfires is likely to result in community functional shifts. Furthermore, stochasticity was also important for community assembly, particularly from the middle towards the end of the hydroperiod. Our results evidenced the strong relevance of successional changes in trait-mediated assembly mechanisms and its interplay with wildfire disturbance in temporary pond communities.

Corrigendum for “Effect of hydric stress on locomotion and morphology of tadpoles from temporary ponds” (vol. 331, issue 3)

This corrigendum is being published to correct an erroneous y-axis labeling in two graphs of Figure 1. Therefore, in both maximum speed panels, the y-axis should be scaled from 0 to 40, and not from 0 to 4. The text remains unchanged. The authors regret this error. The published article can be found here https://onlinelibrary.wiley.com/doi/full/10.1002/jez.2251

Land-use and cultivation in theetaghasof the Tadrart Acacus (south-west Libya): the dawn of Saharan agriculture?

The hyperarid climate of the central Sahara precludes permanent agriculture, although occasional temporary ponds, oretaghas,as a result of rain-fed flooding of wadi beds in the Tadrart Acacus Mountains of the Libyan Sahara allow the pastoral Kel Tadrart Tuareg to cultivate cereals. Geoarchaeological and archaeological data, along with radiocarbon dating and evidence from rock art, however, suggest a much greater antiquity for the exploitation of these etaghas. The authors propose that the present-day cultivation of etaghas mirrors attempts at flood-recession or rain-fed cultivation by late prehistoric Pastoral Neolithic groups, who first exploited residual water resources to supplement their pastoral subsistence practices.

Rift Valley fever in northern Senegal: Amodelling approach to analyse the processes underlying virus circulation recurrence.

Rift Valley fever (RVF) is endemic in northern Senegal, a Sahelian area characterized by a temporary pond network that drive both RVF mosquito population dynamics and nomadic herd movements. To investigate the mechanisms that explain RVF recurrent circulation, we modelled a realistic epidemiological system at the pond level integrating vector population dynamics, resident and nomadic ruminant herd population dynamics, and nomadic herd movements recorded in Younoufere area. To calibrate the model, serological surveys were performed in 2015–2016 on both resident and nomadic domestic herds in the same area. Mosquito population dynamics were obtained from a published model trained in the same region. Model comparison techniques were used to compare five different scenarios of virus introduction by nomadic herds associated or not with vertical transmission in Aedes vexans. Our serological results confirmed a long lasting RVF endemicity in resident herds (IgG seroprevalence rate of 15.3%, n = 222), and provided the first estimation of RVF IgG seroprevalence in nomadic herds in West Africa (12.4%, n = 660). Multivariate analysis of serological data suggested an amplification of the transmission cycle during the rainy season with a peak of circulation at the end of that season. The best scenario of virus introduction combined yearly introductions of RVFV from 2008 to 2015 (the study period) by nomadic herds, with a proportion of viraemic individuals predicted to be larger in animals arriving during the 2nd half of the rainy season (3.4%). This result is coherent with the IgM prevalence rate (4%) found in nomadic herds sampled during the 2nd half of the rainy season. Although the existence of a vertical transmission mechanism in Aedes cannot be ruled out, our model demonstrates that nomadic movements are sufficient to account for this endemic circulation in northern Senegal.

A model of egg bank dynamics in ephemeral ponds

Resting life stages (e.g. dormant seeds and resting eggs) have important implications for ecological and evolutionary processes. In this study, we simulated the impact of different environmental scenarios on the dynamics of resting eggs that make up an “egg bank” of a common fresh water ostracod, Heterocypris incongruens (Crustacea). Our goal was to investigate how the persistence and the wind-mediated spatial distribution of the species in vernal temporary ponds on Lampedusa Island (Southern Italy) were affected. A general model for selection on seed germination in unpredictable environments was used to simulate within pond egg bank dynamics. Metapopulation dynamics were simulated using Levin's and Hanski's models assuming three generalized spatial patterns of pond distribution (random, aggregated along the main wind direction, evenly spaced along the main wind direction) and two dispersion processes (random walk and wind shear). We applied global sensitivity and uncertainty analysis (GSUA) to the models. We estimated the egg bank growth rate based on 30-year simulations under present climatic conditions, and assuming a 2°C rise in winter temperature under global climate change. Hatching rate and deterioration rate were the most important input factors for the dynamics of the egg bank. In warmer winter conditions, the probability that a pond water balance is positive, a reliable hydroperiod estimation, was the most important factor in the egg bank simulation dynamics. Regular distribution of ponds along the wind gradient and wind shear, had the highest dispersal and colonizing potential, considering the percentage of empty ponds reached (60 %). Levins’ model predicted that the equilibrium varied between 0 and 8 % of colonized ponds while Hanski's model predicted values between 0 and 20 %. In Hanski's model the rescue effect increased the probability of occupied ponds. Potential colonizing resting eggs and extinction rate were positively and negatively correlated to the percentage of colonized ponds, respectively. Our simulations can be generalized to aquatic invertebrate taxa that inhabit temporary ponds, have egg banks, colonize habitats using few propagules and disperse passively by wind.