Semi-permanent Ponds Research Articles

Predators balance consequences of climate-change-induced habitat shifts for range-shifting and resident species.

While many species distributions are shifting poleward or up in elevation in response to a changing climate, others are shifting their habitats along localized gradients in environmental conditions as abiotic conditions become more stressful. Whether species are moving across regional or local environmental gradients in response to climate change, range-shifting species become embedded in established communities of competitors and predators. The consequences of these shifts for both resident and shifting species are often unknown, as it can be difficult to isolate the effects of multiple species interactions. Using a model system of insects in high-elevation ponds in the Rocky Mountains of Colorado, we sought to disentangle the effects of predation and intraguild interactions on the survival and development of a semi-permanent pond resident caddisfly Limnephilus externus and the habitat-shifting caddis Asynarchus nigriculus that is being forced into semi-permanent ponds as temporary ponds dry too quickly to complete development. We conducted a manipulative in-situ pond cage experiment in which L. externus and A. nigriculus caddisfly larvae in single-species treatments and together were exposed to the presence/absence of predatory Dytiscus diving beetle larvae. This approach allowed us to isolate the effects of intraguild interactions and predation on the survival and development of both the resident and habitat-shifting species. We found that intraguild interactions had strong negative effects on the resident and habitat-shifting species. Intraguild interactions reduced the survival of the resident L. externus and increased the variation in survival of the shifting A. nigriculus. However, Dytiscus predators reduced these negative effects, stabilizing the community by increasing L. externus survival and reducing variation in A. nigriculus survival. We also found that intraguild interactions reduced L. externus biomass but resulted in increased A. nigriculus development. A. nigriculus development was also increased by predation. Our results show that strong intraguild interactions between resident and shifting species are likely to have negative consequences for both species. However, the presence of predators reduces these negative consequences of the habitat shift on both the resident and the shifting.

DOMESTIKASI IKAN KAPAR (Belontia hasselti) YANG TERTANGKAP DI SUNGAI SEBANGAU

The Kapar fish (Belontia hasselti) is the consumption fish that is obtained only on wild caught. Not yet succeeded in culture this fish, so domestication is needed as an early stage of the aquaculture. The purpose of this research was to knowning the stages of domestication of Kapar fish caught from the Sebangau river in the process of adaptation to new habitats in semi-permanent ponds which is seen from the observation of water quality as well as the growth and survival rate of the Kapar fish. Environmental adaptation for culture fish is the key to successful domestication. Observations of water quality in the fish's wild habitat with the quality of the water where the fish adapt in the pond are slightly different, especially the DO and pH values, but the water quality is still within the tolerance of the Kapar fish to live. The water quality parameters show the temperature in the range 27-29 °C, DO in the range 3-4.2 mg.L-1, and pH in the range 7-7.4. The growth in length and weight during the research showed that the fish were able to adapt feeding. The length and an average weight of Kapar fish until the research were 12.1 cm in length and 31.4 g of weight and it was known that during the research period the absolute length growth of Kapar fish was 1 cm and the absolute weight growth was 8 g . Results of data analysis carried out during the research that the survival rate of Kapar fish is 83 %.

Diet and observations on natural history of Gabohyla pauloalvini (Bokermann 1973) (Amphibia: Hylidae), a poorly known species from cacao agroforestry in southern Bahia, Brazil

Gabohyla pauloalvini is a small Neotropical hylid, known only from three localities besides its type locality. Knowledge about its natural history is scarce and we present the first data about its diet. We conducted our fieldwork during the rainy period between November and December of the years 2014 and 2015. Thirty-eight G. pauloalvini individuals, collected in a semi-permanent pond inside a “cabruca” (cacao plantation shaded by trees), municipality of Ilheus, Bahia, Brazil, were stomach-flushed. All stomach contents were identified to the lower taxonomic category as possible. The Index of Relative Importance (IRI) revealed that Formicidae was the most important prey category for G. pauloalvini. We assume that G. pauloalvini is an ant specialist. Diet records for others species of the tribe Sphaenorhynchini showed mainly ants as prey items, which reinforces an ecological synapomorphy for this tribe. Beyond diet, we also reported observations of possible parental care performed by G. pauloalvini females.

Subsurface delineation of doline features associated with Pleistocene clay-with-flints deposits in the Chilterns: Implications for British Palaeolithic archaeology

Palaeolithic research in the Chiltern Hills (southern England) is important for our understanding of the Pleistocene occupation of Britain, through its record of primary-context assemblages identified by Worthington G. Smith in the late 19th and early 20th centuries. The information available from these sites and surface findspots is limited by the context in which the assemblages were retrieved, but can inform attempts to locate further relevant sites within the region. These previous sites are all focused around doline features that may have acted as semi-permanent ponds or lakes that recurrently or occasionally attracted hominins. Therefore, the present study presents results of a desk-based geographical information system (GIS) analysis, using publicly available national geological datasets, aiming to identify and characterise probable subsurface doline features within the karstic landscape of the Chilterns, with a regional focus on Hyde Heath (Buckinghamshire). Rather than relying exclusively on surface findspot associations, we follow the Unified Palaeolithic Landscape Approach framework in relation to artefact release and preservation to refine which features would be most conducive to in situ primary preservation of hominin activity and behaviour. This also has implications for landscape management policy and preservation of archaeological sites in the region.

Herbicides employed in sugarcane plantations have lethal and sublethal effects to larval Boana pardalis (Amphibia, Hylidae).

The increasing demand for biofuels favored the expansion of sugarcane and, as a consequence, in the consumption of pesticides in Brazil. Amphibians are subject to pesticide exposure for occurring in or around sugarcane fields, and for breeding at the onset of the rainy season when pesticide consumption is common. We tested the hypothesis that herbicides used in sugarcane crops, although employed for weed control and manipulated at doses recommended by the manufacturers, can cause lethal and sublethal effects on amphibian larvae. Boana pardalis was exposed to glyphosate, ametryn, 2,4-D, metribuzin and acetochlor which account to up to 2/3 of the volume of herbicides employed in sugarcane production. High mortality was observed following prolonged exposure to ametryn (76%), acetochlor (68%) and glyphosate (15%); ametryn in addition significantly reduced activity rates and slowed developmental and growth rates. AChE activity was surprisingly stimulated by glyphosate, ametryn and 2,4-D, and GST activity by ametryn and acetochlor. Some of these sublethal effects, including the decrease in activity, growth and developmental rates, may have important consequences for individual performance for extending the larval period, and hence the risk of dessication, in the temporary and semi-permanent ponds where the species develops. Future studies should seek additional realism towards a risk analysis of the environmental contamination by herbicides through experiments manipulating not only active ingredients but also commercial formulations, as well as interactions among contaminants and other environmental stressors across the entire life cycle of native amphibian species.

Reduced abundance but increased diversity of chironomid larvae under higher trophic pressure from fish in semi-permanent ponds

Fish may affect macrobenthic communities through trophic interactions and modification of habitat conditions. We compared the density, diversity and taxonomic composition of larval chironomids under low vs high fish impact, created by stocking semi-natural ponds with either young/small common carp Cyprinus carpio at low biomass densities or with high biomass densities of older/large common carp, supplemented by other cyprinids and predatory fish species.Over the study season, May–August, total chironomid abundance was considerably lower in ponds with high fish biomass than in low fish biomass ponds. In July–August larval densities declined significantly, irrespective of the fish status of the ponds. The composition of larval communities diverged between ponds with different fish status. Chironomus riparius and C. plumosus accounted for most of the observed dissimilarity. C. plumosus densities were not affected by the fish status of the pond, constituting on average >38 % of chironomid specimens in both types of ponds. C. riparius was abundant in ponds with low fish biomass (on average 30 %), but rare in ponds with high fish biomass (4 %). Other common taxa were Glyptotendipes pallens (15 % and 13 %, respectively) and Procladius sp. (14 % in ponds with low fish impact). Canonical correspondence analysis showed that fish biomass was more important in determining chironomid community composition than environmental variables indicative of pond eutrophication (total N, P, chlorophyll a and conductivity).Despite adverse effects on total abundance, chironomid diversity was higher under apparently stronger trophic pressure by fish. Fish may have relieved some chironomid species from invertebrate predation and competition with dominant Chironomus larvae. Other important drivers of chironomid assemblage and diversity patterns may include species-specific feeding modes and prey size selectivity of fish, the ability of chironomid larvae to attain size- and depth-refuge from small fish but not larger fish, and differential vulnerability of free-living and tube-dwelling larvae relative to ontogenetic niche shifts of fish.

Environmental Determinants of Calling Activity and Temporal Body Size Variation in Males of Boana pulchella (Anura: Hylidae) from Southern Uruguay

Amphibian activity is affected by environmental variables, and in some species from tropical and subtropical regions the males in activity are bigger at the beginning of the rainy season than at the end. In this context, the relationship between male calling activity and climatic variables was evaluated in a population of Boana pulchella from Uruguay. This tree frog is distributed from southern Brazil to central and northern Argentina and is a prolonged breeder, enabling us to evaluate temporal male body size variations. The study population was in a temperate region with seasonal variation of temperature and aseasonal rainfall. Monthly mean temperatures and total rainfall were obtained from a meteorological station 15 km from the semi-permanent pond where the sampling work was conducted. From November 2005 to November 2006, 10 m from this pond, and three days per month, air temperature and relative humidity were recorded, and monthly photoperiods were calculated. From 20:00–22:00 on the days climatic variables were determined, the activity of B. pulchella was measured through an acoustic and visual encounter survey. In addition, animals were collected, measured, and released. Male activity was not correlated with either mean temperature or photoperiod. This was compatible with the aseasonal male activity calculated with circular statistics. However, male activity was positively correlated with rainfall. The occurrence of froglets was seasonal, concentrated mainly in November 2005. The males in the cold season were larger than those in the warm season. Qualitative comparison among calling phonologies at different latitudes indicated B. pulchella was inactive during some cold months in the south and during some warm months in the north. This geographical variation in calling phenology indicates that local environmental temperatures affect activity and likely reproduction of B. pulchella, with the optimum being in the range of cold to mild.

Informing Amphibian Conservation Efforts with Abundance-Based Metapopulation Models

Science-based management strategies are needed to halt or reverse the global decline of amphibians. In many cases, sound management requires reliable models built using monitoring data. Historically, monitoring and statistical modeling efforts have focused on estimating occupancy using detection–nondetection data. Spatial occupancy models are useful for studying colonization–extinction dynamics, but richer insights can be gained from estimating abundance and density-dependent demographic rates. We developed an integrated abundance-based metapopulation model of the processes contributing to spatiotemporal variation in patch population density. We fit our model to a combination of detection–nondetection and count data from a 14-yr study of a reintroduced metapopulation of federally threatened Chiricahua Leopard Frogs (Lithobates chiricahuensis). Pond-specific population growth rate was influenced by pond hydroperiod and frog density, such that permanent and semipermanent ponds with low densities of adult frogs experienced the highest annual population growth rates. Immigration rate declined as the distance among ponds increased. After reintroduction in 2003, metapopulation-level abundance increased and appeared to stabilize around 1300 adult frogs (95% CI = 1192–1471) by year 2015. Further, changes in metapopulation abundance were driven mostly by changes in abundance at a few ponds. These high-density populations, which would not have been identifiable with traditional occupancy-based metapopulation models, are likely especially important for species recovery in the area. Abundance-based metapopulation models can be widely applied to inform conservation efforts, by providing higher quality information needed to prioritize habitat patches for management and can be used to make more accurate predictions of metapopulation extinction risk.

Carbon Dioxide Concentrations and Efflux from Permanent, Semi-Permanent, and Temporary Subalpine Ponds

Small ponds account for a disproportionately high percentage of carbon dioxide emissions relative to their small surface area. It is therefore crucial to understand carbon flow in these ponds to refine the current global carbon budget, especially because climate change is affecting pond hydrology. High elevation ponds in the Elk Mountains of western Colorado are drying more frequently as the timing of snowmelt advances. We compared CO2 concentrations and fluxes among ponds of different hydroperiods over diel sampling periods during the course of the 2017 open-water period. CO2 concentrations were significantly negatively correlated with pond depth and averaged 77.6 ± 24.5 μmol L−1 (mean ± S.E.) across all ponds and sampling events. Ponds were up to twenty times supersaturated in CO2 with respect to the atmosphere. Flux was highly variable within individual ponds but correlated with time of sampling and was highest at night. Flux averaged 19.7 ± 18.8 mg CO2 m−2 h−1 across all ponds and sampling events. We also compared flux values obtained using modeled and empirical methods and found that widely-applied models of gas exchange rates using wind-based gas exchange (K) values yielded estimates of CO2 flux that were significantly higher than those obtained using the floating chamber approach, but estimates of CO2 flux using globally averaged convection-based K values were lower than those obtained using the floating chambers. Lastly, we integrated soil vs. water efflux measurements with long-term patterns in hydrology to predict how total season-long efflux might change under the more rapid drying regimes and longer seasons that are already occurring in these systems. Because soil CO2 efflux averaged 277.0 ± 49.0 mg CO2 m−2 h−1, temporary ponds emitted 674.1 ± 99.4 kg CO2 m−2 over the course of the 2017 season from ice-out to refreezing, which was over twice as much as permanent and semi-permanent ponds. Our results emphasize that contributions of CO2 from small ponds to the global carbon budget estimates will vary with pond hydroperiod and sampling methodology, which have been overlooked given that most previous estimates were collected from limited sampling periods and from pond waters alone. Furthermore, pond CO2 contributions are predicted to increase over time as pond areas transition from efflux from water to efflux from soil.

Historias de vida y demografía de Physalaemus biligonigerus (Anura: Leptodactylidae) en una charca periurbana del centro de Argentina

Demography and life histories of Physalaemus biligonigerus (Anura: Leptodactylidae) in a peri-urban pond in central Argentina. Knowledge of population dynamics provides information on the recent history, current status, and future trends of a population. Physalaemus biligonigerus is widely distributed in the Neotropics, this anuran has a high and explosive reproductive activity, but its populations seem to be composed of young individuals. The objective of this study was to analyze the population demography of P. biligonigerus in a semipermanent pond in Río Cuarto, Córdoba, Argentina and to carry out a population projection through 30 generations. The age structure was determined from the use of skeletochronology, and a static life table was later made. Fertility and survival rates were calculated for each stage, by which a Leslie Matrix was constructed and the population projection was performed. The projection shows oscillations in the number of individuals but in spite of this, the final tendency of the population is an increase in its size. The highest proportion of survivors occurs in the egg-to-larval stages and the mortality force acts intensively on the larval phase. The net reproductive rate indicates that the population of P. biligonigerus of the study pond is increasing. Rev. Biol. Trop. 66(2): 765-775. Epub 2018 June 01.

Seasonality of dipteran-mediated methylmercury flux from ponds.

Methylmercury (MeHg) is an aquatic contaminant that can be transferred to terrestrial predators by emergent aquatic insects. We assessed the effects of month and pond permanence on dipteran-mediated MeHg flux (calculated as emergent dipteran biomass × dipteran MeHg concentration) in 10 experimental ponds. Emergent dipterans were collected weekly from permanent ponds with bluegill (Lepomis macrochirus; n = 5) and semipermanent ponds without fish (n = 5) over a 7-mo period (February-August, 2015). We detected a significant effect of month on MeHg flux from 6 dipteran taxa and aggregate MeHg flux, with the highest MeHg flux from herbivorous/detritivorous chironomid midges and predatory midges in March; biting midges, phantom midges and herbivorous/detritivorous orthoclad midges in April; and mosquitoes in August. Aggregate dipteran-mediated MeHg flux peaked in April and then declined throughout the remainder of the summer. We did not detect a significant main effect of pond permanence or a significant month × pond permanence interaction effect on MeHg flux for any of the taxa examined in the present study or for aggregate MeHg flux. Given their ubiquity in aquatic systems and their importance in food webs at the land-water interface, dipterans are important taxa that should not be overlooked as a part of the Hg cycle. Environ Toxicol Chem 2018;37:1846-1851. © 2018 SETAC.

Seasonality of odonate-mediated methylmercury flux from permanent and semipermanent ponds and potential risk to red-winged blackbirds (Agelaius phoeniceus).

Methylmercury (MeHg) is an aquatic contaminant that can be transferred to terrestrial predators by emergent aquatic insects such as odonates (damselflies and dragonflies). We assessed the effects of month and pond permanence on odonate-mediated MeHg flux (calculated as emergent odonate biomass × MeHg concentration) in 10 experimental ponds and the potential risk to nestling red-winged blackbirds (Agelaius phoeniceus) posed by consuming MeHg-contaminated odonates. Emergent odonates were collected weekly from permanent ponds with bluegill (Lepomis macrochirus; n = 5) and semipermanent ponds without fish (n = 5) over an 8-mo period (January-August 2015). The MeHg flux from damselflies, aeshnid dragonflies, and libellulid dragonflies began in March and peaked in April, May, and June, respectively, and then declined throughout the rest of the summer. Odonate-mediated MeHg flux from semipermanent ponds without fish was greater than that from permanent ponds with fish. Nesting of red-winged blackbirds overlapped with peak odonate emergence and odonate-mediated MeHg flux. Because their diet can be dominated by damselflies and dragonflies, we tested the hypothesis that MeHg-contaminated odonates may pose a health risk to nestling red-winged blackbirds. Concentrations of MeHg in odonates exceeded wildlife values (the minimum odonate MeHg concentrations causing physiologically significant doses in consumers) for nestlings, suggesting that MeHg-contaminated odonates can pose a health risk to nestling red-winged blackbirds. Environ Toxicol Chem 2017;36:2833-2837. © 2017 SETAC.

Recovery of aquatic insect-mediated methylmercury flux from ponds following drying disturbance.

Small ponds exist across a permanence gradient, and pond permanence is hypothesized to be a primary determinant of insect community structure and insect-mediated methylmercury (MeHg) flux from ponds to the surrounding terrestrial landscape. The present study describes the first experiment examining the recovery of insect-mediated MeHg flux following a drying disturbance that converted permanent ponds with insectivorous fish to semipermanent ponds without fish. Floating emergence traps were used to collect emergent insects for 10 wk in the spring and summer from 5 ponds with fish (permanent) and 5 ponds that were drained to remove fish, dried, and refilled with water (semipermanent). During the 73-d period after semipermanent ponds were refilled, total MeHg flux from semipermanent ponds was not significantly different than total MeHg flux from permanent ponds, indicating that insect-mediated MeHg flux had rapidly recovered in semipermanent ponds following the drying disturbance. Methylmercury fluxes from dragonflies (Odonata: Anisoptera) and phantom midges (Diptera: Chaoboridae) were significantly greater from newly refilled semipermanent ponds than permanent ponds, but the MeHg fluxes from the other 8 emergent insect taxa did not differ between treatments. The present study demonstrates the impact of drying disturbance and the effect of community structure on the cross-system transport of contaminants from aquatic to terrestrial ecosystems. Environ Toxicol Chem 2017;36:1986-1990. © 2017 SETAC.

New larval trematodes in Biomphalaria species (Planorbidae) from Northeastern Argentina.

Larval trematodes infecting Biomphalaria tenagophila and B. occidentalis were surveyed in a suburban and semipermanent pond of Corrientes province, Northeastern Argentina. A total of 1,409 snails were examined between spring 2011 to winter 2013, and 8 different larval trematodes were studied morphologically. Three of these species-Echinocercaria sp. IV, Ribeiroia sp. and Echinocercaria sp. XIV-have been previously found in Corrientes province. Six other trematodes belonging to Strigeidae (Furcocercaria sp. III), Clinostomidae (Cercaria Clinostomidae sp.), Spirorchiidae (Cercaria Spirorchiidae sp.) and Echinostomatidae (Echinocercaria sp. 1, Echinocercaria sp. 2, Echinocercaria sp. 3) are new species parasitizing Biomphalaria snails. Cercaria Spirorchiidae sp. is the third larval trematode related to Spirorchiidae recorded in South America and the first one for Argentina. Cercaria Clinostomidae sp. is the first one related to Clinostomidae in northeastern Argentina. The prevalence of larval trematodes infecting B. tenagophila and B. occidentalis in the environment studied was low (<5%) with the echinostome group better represented in terms of prevalence and species richness. Drought periods could affect the dynamics of parasitic transmission due to the absence of trematodes in the autumn and winter of the first seasonal cycle. However, in humid periods parasite transmission can occur throughout the year due to the presence of larvae in all seasons of the second seasonal cycle, although the less-warm seasons showed higher prevalence than the summer period probably related to the subtropical climate of Corrientes province.

Permanent and temporary ponds in Doñana National Park (SW Spain) are threatened by desiccation

Permanent and temporary ponds in Donana National Park (SW Spain) are threatened by desiccation In Donana National Park, most aquatic habitats are temporary. Ponds dry up during the summer, and are filled again when phreatic levels rise after heavy rains. Permanent and semipermanent ponds, and a chain of long-hydroperiodponds are formed in an area of the park where discharges of the dune and regional aquifers coincide. Over the last few decades, groundwater abstractions have severely affected the park. Using Landsat images (1975-2014), we estimated the variation in the inundatedareasof the park's largest ponds. All ponds have increased their dependencyon annual rainfall in recent decades. Two seasonal ponds located close to urban pumping stations are currently dry. We found that other seasonal ponds have tended to have shorter hydroperiod and have dried up in the summer in recent years, including in very rainy years. The largest permanent pond had not such wide interannual fluctuations in its inundated area in the 1970s as those experienced recently. During the last decades, its inundated area is strongly correlated with annual rainfall, and the pond is close to desiccation in years of low rainfall. These results show that this pond network is severely threatened by desiccation. It is urgent to control groundwater extraction in the area to preserve the integrity of this important wetland.

Sedimentology and vertebrate taphonomy of the Moradi Formation of northern Niger: A Permian wet desert in the tropics of Pangaea

Pangaean paleogeographic models place the Tim Mersoi basin of northern Niger in a 5000-km-wide corridor between Gondwana and Laurasia approximately 15 degrees south of the paleoequator. Late Permian paleoclimate models position this basin between tropical summer-wet to the north and desert to the south. Recent investigations of the fossil vertebrates and paleosols in the late Permian (Lopingian) Moradi Formation confirm that the climate was warm and hyperarid with highly seasonal monsoonal rainfall. Possibly as a result of these unusual “wet desert” conditions, the tetrapod fauna shows a high degree of endemism. This study tests existing paleoclimate models by providing additional data on sedimentary environments and vertebrate taphonomic processes. The Moradi red bed sequences accumulated in a gently subsiding sag basin to the west of the tectonically active Massif de l'Aïr. Low angle gravelly alluvial fans prograded westward from the massif and at times impinged on a large stable northward flowing meandering channel system. The interchannel mudrock sequences are over-thickened by the accumulation of loessic silts and preserve isolated skull and post crania of amphibians (Nigerpeton and Saharastega) as well as semi-articulated captorhinids (Moradisaurus). Detailed surface mapping of a fossil-rich exposure revealed an anastomosed network of loess-filled distributary channels incised into the floodplain mudrocks. This provided a locus for the accumulation and rapid burial of at least 15 associated skeletons of the pareiasaurian Bunostegos. Semi-permanent ponds are evidenced by patches of fissile red mudstone containing rare bivalves and spiral coprolites. In the distal floodplains away from the main river channels, the combination of a generally high groundwater table, warm mean annual temperatures, and deflation of fines from the floodplain surface promoted the formation of gypsiferous paleosols and end-point playa lakes. Carbonate-rich mud accumulated around the lake margins and provided ideal conditions for the imprinting and preservation of tetrapod trackways.

An environmental problem hidden in plain sight? Small human-made ponds, emergent insects, and mercury contamination of biota in the Great Plains.

Mercury (Hg) contamination of small human-made ponds and surrounding terrestrial communities may be 1 of the largest unstudied Hg-pollution problems in the United States. Humans have built millions of small ponds in the Great Plains of the United States, and these ponds have become contaminated with atmospherically deposited mercury. In aquatic ecosystems, less toxic forms of Hg deposited from the atmosphere are converted to highly toxic methylmercury (MeHg). Methylmercury is incorporated into the aquatic food web and then can be transferred to terrestrial food webs via emergent aquatic insects. The authors present a conceptual model that describes the movement of MeHg produced in aquatic ecosystems to terrestrial consumers via insects emerging from small human-made ponds. The authors hypothesize that pond permanence and the level of Hg contamination of the food web control this emergent insect-mediated flux of MeHg. The highest insect-mediated flux of MeHg is predicted to be from fishless semipermanent ponds with food webs that are highly contaminated with MeHg. Further development and testing of the conceptual model presented in the present column, particularly in the context of a changing climate, will require research at the regional, watershed, and pond scales.

Long-term monitoring of astatic water bodies: microcrustaceans as indicators of hydroperiod length in ponds and pools

Microcrustacean assemblages (Cladocera and Copepoda) from astatic ponds and pools of Castelporziano Presidential Estate were analysed to evaluate their role as indicators of functional variations related to the duration of the wet phase. Samples from a subset of 23 water bodies classified as permanent or temporary (based on observations over two decades, 1989–2010) were analysed. As a whole, 36 species of microcrustaceans were present. Hierarchical clustering allowed a clear distinction between temporary and permanent water bodies. Principal coordinates analysis (PCoA) provided a good separation of the two major hydroperiod groups along the first axis, while no correlation emerged among PCoA axes and hydrogeological setting. The correlation between species and the first PCoA axis highlighted biological indicators of hydrological change: among them, the cyclopoid copepods Macrocyclops albidus and Eucyclops serrulatus, which have no resting stages, were exclusive of permanent ponds; the calanoid copepod Eudiaptomus padanus etruscus and the cladocerans Ceriodaphnia reticulata, Scapholeberis rammneri and Coronatella rectangula were present in permanent and semi-permanent ponds; the cladoceran Daphnia chevreuxi and the calanoid copepods Diaptomus serbicus, Hemidiaptomus gurneyi and Mixodiaptomus kupelwieseri were exclusive of temporary ponds with short hydroperiod (less than 6 months). Temporary water bodies hosted a higher mean species richness (13.7 species) than permanent ones (10.3), and the difference was statistically significant. Our results highlight that: (1) the cladoceran and copepod assemblage effectively discriminate between ponds with different wet phase duration, proving to be good bioindicator; (2) small astatic water bodies play an important role in biodiversity conservation, as they host a high percentage of the species distributed over wider areas, next to species which are exclusively found in these habitats; (3) hydroperiod appears to be the main driving force in characterising microcrustacean assemblages in astatic ponds.

Dragonfly and Damselfly Colonization and Recolonization of a Large, Semi-Permanent Pennsylvania Pond

Odonata (dragonflies and damselflies) at Ten Acre Pond in central Pennsylvania have been monitored on a yearly, monthly, and often weekly basis for over half a century, making the Odonata fauna of the pond the most thoroughly documented of any habitat in the United States. Here we summarize the yearly and seasonal distribution of all species reported from 1955 through 2011. Of the 938 Odonata surveys at this semi-permanent pond, 60% are since 1994 when observations were last summarized. Of the 86 species observed at least once, 14 appeared since 1994. Several species that were rare or absent before 1980 have established transient populations, and a few with southern affinities have become well established. The pond's water levels often fluctuate dramatically from year to year and through the year. For populations of “resident” species, recolonization from other local populations occurs efficiently after periods of drought.

Diversidade de anfíbios anuros de uma área de Pampa no município de São Gabriel, Rio Grande do Sul, Brasil

Considerado um bioma ameaçado, o Pampa possui um dos menores percentuais de área legalmente protegida. Além disso, o conhecimento sobre comunidades de anuros neste bioma ainda é escasso. Nesse contexto, o objetivo deste estudo foi determinar a composição de anuros em uma área de Pampa no sul do Brasil. Entre janeiro de 2009 e fevereiro de 2010 foi realizado um inventário na Fundação Estadual de Pesquisa Agropecuária do município de São Gabriel, Rio Grande do Sul. A procura dos exemplares foi realizada em poças permanentes, semi-permanentes e temporárias pelo método de levantamento em sítio de reprodução. Foram registradas 21 espécies pertencentes a cinco famílias, o que corresponde a aproximadamente 20% das espécies do estado e 42% das espécies conhecidas para a ecorregião Savana Uruguaia. Dez espécies foram consideradas frequentes, sete comuns e quatro foram raras. Foram registrados três modos reprodutivos, sendo que 57% das espécies utilizam o modo 1, que parece estar relacionado à homogeneidade da área. A análise de agrupamento comparando a composição de anuros de quatro localidades distintas mostrou maior similaridade com o município de Candiota (região da Campanha). As espécies presentes na área de estudo são associadas a formações campestres do estado e países vizinhos e podem ser consideradas típicas do bioma Pampa.