Insects associated to ephemeral pools in Huentelauquén (29ºS Coquimbo Region, Chile)

In northern central Chile, ephemeral pools constitute shallow isolated water bodies with a favourable habitat for fauna adapted to seasonal changes. Based on the limited knowledge about the fauna—particularly insects—associated to these ecosystems, the objective of this study was to characterize the richness, composition, structure and similarity of the insect communities associated with ephemeral pools in Huentelauquén (29º S, Coquimbo Region, Chile). By using pitfall traps, 10,762 individuals were captured, represented by 7 orders, 27 families, and 51 species. Coleoptera and Hymenoptera were the best represented orders, with Neuroptera, Orthoptera and Plecoptera being poorly represented groups. The non-parametric estimators evaluated showed wealth values above those observed for all the studied pools, and their accumulation curves suggest the existence of an incomplete species inventory in the studied community. Additionally, the hierarchical and ordering analysis showed groupings of pools located in the northwest and southeast of Huentelauquén. Preliminarily we found a negative correlation between the area of the pools and the richness (species) and abundance of insects. Additional studies (on other arthropod groups and other seasons of the year) could provide a better understanding of the local processes of extinction and colonization of the species inhabiting these fragile coastal environments.

Inter-element variation in the bone histology of Anteosaurus (Dinocephalia, Anteosauridae) from the Tapinocephalus Assemblage Zone of the Karoo Basin of South Africa

Despite its abundance in the Permian fossil record of South Africa, little is known about the life history of Anteosaurus. Here we examine the bone microstructure of multiple skeletal elements of Anteosaurus from the Tapinocephalus Assemblage Zone of the Karoo Basin. The bone histology of Anteosaurus magnificus reveals that the cortex is composed of highly vascularized, uninterrupted fibrolamellar bone tissue surrounding the inner spongy medullary region. However, the histology of two ribs and a previously described femur of another Anteosaurus taxon revealed an interrupted growth pattern with lines of arrested growth and peripheral rest lines occurring in the compacta, indicating periodic pauses in growth possibly linked to the slowing down of growth during maturity. Given that the fibula of the same individual has well-vascularised fibrolamellar bone tissue without any growth marks in the cortex; this suggests variation in skeletal growth. Based on our histological results, three growth dynamic stages are deduced for the genus Anteosaurus: (i) the earliest growth stage is represented by the predominance of highly vascularized, uninterrupted fibrolamellar bone tissue in the inner cortex, which suggests rapid periosteal bone deposition during early ontogeny; (ii) the next stage of growth shows periodic interruptions in the bone deposition as indicated by the deposition of lines of arrested growth; (iii) the third stage shows the development of lamellar bone tissue with rest lines in the peripheral part of the cortex suggesting a slowing down of growth prior to death. Most of the skeletal elements are characterized by thick bone walls, extensive secondary reconstruction and the complete infilling of the medullary cavity. However, the radius and a previously studied femur have open medullary cavities with struts of bony trabeculae. Based on histologic structures and comparisons with extant taxa, it is likely that Anteosaurus may have been more terrestrial as its osteology point towards terrestriality, but it may have occasionally inhabited ephemeral pools like modern semi-aquatic Hippopotamus.

Alternanthera sessilis (sessile joyweed).

A. sessilis is a pioneer species typically growing on disturbed areas and in wetland habitats, and regarded as a fast-growing highly invasive weed. It is adapted to grow on a range of soil types ranging from poor sandy or alkaline soils, to loam or black cotton soils. It is also able to grow in seasonally-waterlogged areas as well as in areas with extreme dry conditions (Holm et al., 1997). A. sessilis can be found invading floodplain wetlands, margins of rivers, streams, canals, ditches, ponds, reservoirs, tanks, marshes, swamps, wet low-lying ground, ephemeral pools, seasonal pans and damp forest. This species is also a weed in fields with sorghum, millet, Eleusine spp., maize, cotton, cassava, cereal crops, pastures, and vegetable farms (Gupta, 2014). Consequently, this species has been listed as invasive in India, South Africa, Namibia, Spain, Hawaii and many other islands in the Pacific Ocean (see distribution table for details). It is also listed as a noxious weed in the United States (USDA-NRCS, 2014).

Influence of morphometric parameters and meteorological conditions on ephemeral pool hydrology in the Canadian Shield forest

<p>Ephemeral pools are geographically isolated wetlands commonly found in temperate forests of northeastern North America. These wetlands are usually hydrologically isolated from the surface water network but in some conditions can be connected to local groundwater flow. They fill at maximal capacity following spring snowmelt and dry out during summer. They contribute to forest biodiversity by providing breeding habitats for amphibians during their spring and early summer period of hydrological activity. However, ephemeral pools are poorly understood and rarely studied because of their small dimensions and temporary hydrology. This work presents the final results of a five-year study aimed to acquire new knowledge on ephemeral pool hydrology to go beyond the anecdotical pool and to understand the conditions and processes that driving their hydrology. A large number of pools (39) located in the Canadian Shield forest were instrumented to monitor hourly water level variations in the pool and in the neighboring and underlying fractured bedrock aquifer. They were also described in extensive details for their geomorphological features and water levels over a period from one to five years (April 2016 to July 2020). The first rather surprising result from this work is that, although the pools are all located in bedrock depressions, they cover a wide range of morphologies. Their maximum sizes vary from 29 to 1866 m<sup>2</sup> and their maximal volumes vary from 4 to 654 m<sup>3</sup>. Their maximum water depths are also highly contrasted, ranging from 0.14 m to 2.03 m. The pool depressions are overlain by mineral sediments (silt to fine sand with occurrences of coarse sand and gravel) of contrasted thicknesses (0 m to 1.70 m). An organic matter layer of highly varying thickness (0.12 m to 1.24 m) was observed at all sites above the mineral sediments. Despite these varied morphological conditions, all the pools have similar hydrological patterns throughout the year and these patterns are highly resilient to meteorological conditions. They dry out between the end of May and the end of July, rapid temporary refilling during important summer rainfall events, and partially refilling in autumn following more frequent rainfall events and lower evapotranspiration. The results show that surface water levels are maintained when the underlying sediments are saturated. Otherwise, the ephemeral pools lose water by infiltration to the underlying aquifer. Water level variations within the pools are positively and significantly correlated with net precipitation (P – PET). Hydroperiods vary between 28 days (2020) and 86 days (2017), reflecting the year-to-year meteorological variability. The mean hydroperiod is significantly correlated to spring rainfall (April to June), but also to the volume of water stored in the pool, and to the pool surface area. This study provides a unique and original dataset that contribute to better understand the hydrodynamics and resilience to anthropogenic (forestry) and natural (climate change) impacts of a wetland type that is rarely studied but provide crucial habitats for forest biodiversity.</p>

An improved representation of ephemeral pool hydrology in a semi-distributed hydrologic model

<p>Ephemeral pools are seasonally flooded geographically isolated wetlands with distinct hydrology i.e., they are filled in winter and spring with inflow from snowmelt, and precipitation and dry out during summer. Ephemeral pools offer a variety of biodiversity benefits notably providing breeding habitat for several amphibian and invertebrate species. The quality of their ecosystem services is mainly controlled by their hydroperiod which is regulated by hydrology i.e., inflow /outflow of the pools. The classic water budget modeling approach with a simplified representation of the flow exchange between the pool and surface-subsurface zones may not adequately reveal their sensitivity to anthropogenic interventions and climatic changes. On the other hand, the generic volume-area-depth relationship of isolated wetlands in deterministic hydrologic models may not adequately reveal their dynamic water level fluctuations. The objective of this study, in the first place, is to improve the representation of ephemeral pools in the semi-distributed SWAT hydrological model, notably in the pothole module which is used for modeling isolated wetlands. The developed model will then be used to analyze the impact of land use and climate changes on dynamics of hydroperiods of ephemeral pools of the Saumon River watershed (68 km<sup>2</sup>) in the Canadian Shield of the Outaouais region (Quebec, Canada). A detailed bathymetry survey along with a long series (one to five years) of daily water level measurements available at ten pools allowed to replace the simplified linear volume-area relationship with the measured rating curve for the ephemeral pools in this region. The calibration process of the revised model is performed using the standard SWAT calibration code (SWAT-CUP) coupled to a Particle Swarm Optimization (PSO) algorithm adjusting evaporation and seepage coefficients of the revised module for all isolated wetlands of the region. This double calibration ensures representation of both the watershed hydrology (10 years of river flow rates) and the water level fluctuations in the pools. The simulation results show that the revised SWAT version can adequately reproduce the dynamic water level behavior of the monitored pools as well as streamflow discharges. The model is currently used with scenarios of human and climatic disturbances to understand their impact on the filling-drying cycle of ephemeral pools and on the integrated hydrologic system at the watershed scale.</p>

Development of the African Killifish as a New Model to Study Aging and Suspended animation

We have pioneered a new model organism for aging research, the naturally short-lived African killifish Nothobranchius furzeri. The African killifish lives in ephemeral pools of water in Africa, and has evolved a short life cycle adapted to this habitat. Its embryos can also resist drought until the next wet season in a state of ‘suspended life’. In laboratory conditions, the African killifish has a maximal lifespan of about 4-6 months, and is, so far, the shortest-lived vertebrate that can be bred in captivity. We have successfully transformed this natural short-lived vertebrate into a usable model organism for aging research, including de novo assembly of the genome and CRISPR-Cas9 mediated genome-editing. Our goal is to use this model to discover new principles underlying aging, longevity, and ‘suspended animation’ in vertebrates.

Urbanization and Evolution in Aquatic Environments

Human impacts on freshwater and marine ecosystems have long been of special concern due to water’s essential role in ecosystem functioning and human civilization. Urban development causes a large number of changes in all types of aquatic environments, from small ephemeral pools to rivers to great lakes to expansive coastal habitats. These changes can strongly influence evolution of life in the water by altering selection, gene flow, and genetic drift. Yet our understanding of the evolutionary consequences of urbanization on aquatic organisms is still in early stages. This chapter reviews the impacts of urbanization on aquatic taxa, examining the evolutionary consequences (known or likely) of four major types of urban-induced changes to ecosystems: biotic interactions, physical environment, temperature, and pollution. By drawing connections between literature on ecological and evolutionary impacts in aquatic urban environments, the chapter concludes that (1) several anthropogenic factors seem to commonly drive evolutionary and phenotypic change (organic-compound pollution, altered temperature, and hydrologic shifts), (2) predictability of evolutionary changes are often taxa specific, and may commonly depend on the focal ‘scale’ (e.g., whole-organism performance, morphology, or gene), and (3) there are a few key ‘frontier topics’ (altered biotic interactions, artificial light, sound pollution, and fragmentation) where additional research on phenotypic evolution would be particularly informative.

Better understanding the hydrology of peri-urban ephemeral pools serving as habitats for the Western Chorus Frog

<p>Ephemeral (vernal) pools are small hydrologically isolated wetlands found in a large variety of environments across the world. They provide breeding habitats for amphibians during their spring and early summer period of hydrological activity. Because of their small size and intermittent nature, many questions remain unanswered about their hydrology and concerning best strategies to improve their resilience to human activities and climate change. In the peri-urban area around Montreal City (Monteregie region, Quebec, Canada), ephemeral pools are habitats to the endangered Western Chorus Frog. In an attempt to protect the remaining population and to improve the reproductive success of these frogs, a study was funded by the Quebec Ministry of forest, fauna and parks to understand the processes driving pool hydrology and especially pool hydroperiod (length of hydrologically active period after snowmelt). Fourty-eight pools located in forested, agricultural and low-density housing developments were monitored for water levels since 2015. Seven of these pools were fully characterized for bathymetry and geology (field measurements), groundwater levels (hourly monitoring) and drainage area (LiDAR data). The pools are located on relatively flat land, in shallow irregular basins within generally low permeability Quaternary sediments. The pools hold relatively small volumes of water, with maximum annual water depths between 0.2 and 1.1 m (observed in April or May). Their areas vary between 100 and 5000 m<sup>2</sup>. The hydrologically active periods after snowmelt (starting after the last frost when mean temperature > 5°C over five days and ending when the pool is dry) vary between 15 and 150 days. At some sites, the hydroperiods were shorter than the required length for reproductive success of the Western Chorus Frog, which could explain the population decline. These short hydroperiods appear to be linked to the presence of human impacts in the pool vicinity. Water level reactions after precipitation are indications that pool hydrology is influenced by a relatively small contributing area rather than by their apparent drainage area (ratio Δh/rain < 4). Head gradients between water levels in the nearby sediments and pool water levels underline the role of the shallow groundwater in maintaining humid conditions in the pools and in reactivating the pools during the summer.  Simple water budget models  confirm this groundwater input and show that surface and hypodermic runoff is the main water source to the pools. The models show that, pool hydroperiods will start earlier under a changing climate, because of warmer winters, but will not necessarily be longer due to higher temperatures and increased evapotranspiration. The models will be used to estimate the effects of human interventions (e.g. drainage, residential) on pool hydroperiods, thus contributing to plan pool protection strategies that could help protect the Western Chorus Frog.</p>

Seasonal vegetation shift and wetland dynamics in vulnerable granitic rocky outcrops of Palghat Gap of southern Western Ghats, Kerala, India

Low altitude granitic hillock systems prevalent in Palghat (Palakkad) Gap region of southern Western Ghats were analyzed for seasonal dynamics in wetland taxa associated with marshy ephemeral flush vegetation, small ephemeral pools and deep rock pools. Due to characteristic habitat features, such systems harbor a unique pattern of microhabitats and associated floristic components. Wet phase in rocky outcrops in the monsoon season establishes a hydro-geomorphic habitat that supports establishment of wetland taxa like Eriocaulon, Drosera, Utricularia, Dopatrium, and Rotala. Seasonal shift in the floral associations was evident in tune with wetland dynamics. Wet rocks support ephemeral flush vegetation which display some unique plant associations of species of Eriocaulon, Utricularia, Drosera, Cyanotis, Murdannia, and Lindernia. Small ephemeral pools displayed taxa like Rotala malampuzhensis R.V. Nair, Dopatrium junceum (Roxb.) Buch.-Ham. ex Benth., D. nudicaule (Willd.) Benth., Monochoria vaginalis (Burm.f.) C. Presl, and Cyperus iria L. Rocky pools are the habitats of aquatic angiosperms like Nymphaea nouchali Burm. f., Ludwigia adscendens (L.) H. Hara, Utricularia aurea Lour. and Hydrilla verticillata (L.f.) Royle. The study documented 121 plant taxa from 37 families during a wet phase from rocky outcrops of the study area. Gradual shift in vegetation is evident as water recedes from granitic hillocks. During the period from December to March, the rocky pools dry up which results in a shift in the vegetation pattern where Poaceae members form the dominant elements. As most of the rocky outcrops are exposed to extreme temperature and acute water shortage, the taxa inhabiting such ecosystems tend to evolve much faster than in other habitats. Moreover, the vicinity of these hillocks in the Palghat Gap region to human settlements, face threats like fire, grazing, quarrying, dumping of wastes etc. which may cause considerable loss to the very sensitive plant communities which are not yet fully documented.