Temporary Pools Research Articles

A Review of charophytes of the Cleveland-Lloyd Dinosaur Quarry at Jurassic National Monument in the upper part of the Morrison Formation (Late Jurassic), Emery County, Utah, USA

The Cleveland-Lloyd Dinosaur Quarry at Jurassic National Monument in central Utah has been extensively studied for nearly 80 years. During this time, studies have heavily focused on the taphonomy, depositional setting, and potential behavioral inferences of the most dominant vertebrate taxon at the quarry, Allosaurus fragilis. However, despite their importance for paleoecological interpretations, microfossils from the quarry, such as charophytes and ostracods, have been conspicuously absent from any detailed discussion in the literature. Here we present a review of the known taxa of charophytes from the Cleveland-Lloyd Dinosaur Quarry and test the variability of abundance and taphonomic conditions throughout the quarry deposit. Our results indicate that significant differences in charophyte abundances exist in the lower and upper parts of the quarry, and a wide variance of taphonomic conditions is present in charophyte gyrogonites in the uppermost contact with the overlying carbonate bed. These results support prior interpretations of the Cleveland-Lloyd Dinosaur Quarry as an ephemeral pond and bring further attention to the importance of microfossils in paleoecological reconstructions.

Ecological information and approaches needed for risk communication dialogs for acute or chronic environmental crises.

Scientists, social scientists, risk communicators, and many others are often thrust into a crisis situation where they need to interact with a range of stakeholders, including governmental personnel (tribal, U.S. federal, state, local), local residents, and other publics, as well as other scientists and other risk communicators in situations where information is incomplete and evolving. This paper provides: (1) an overall framework for thinking about communication during crises, from acute to chronic, and local to widespread, (2) a template for the types of ecological information needed to address public and environmental concerns, and (3) examples to illustrate how this information will aid risk communicators. The main goal is providing an approach to the knowledge needed by communicators to address the challenges of protecting ecological resources during an environmental crisis, or for an on-going, chronic environmental issue. To understand the risk to these ecological resources, it is important to identify the type of event, whether it is acute or chronic (or some combination of these), what receptors are at risk, and what stressors are involved (natural, biological, chemical, radiological). For ecological resources, the key information a communicator needs for a crisis is whether any of the following are present: threatened or endangered species, species of special concern, species groups of concern (e.g., neotropical bird migrants, breeding frogs in vernal ponds, rare plant assemblages), unique or rare habitats, species of commercial and recreational interest, and species/habitats of especial interest for medicinal, cultural, or religious activities. Communication among stakeholders is complicated with respect to risk to ecological receptors because of differences in trust, credibility, empathy, perceptions, world view valuation of the resources, and in many cases, a history of misinformation, disinformation, or no information. Exposure of salmon spawning in the Columbia River to hexavalent chromium from the Hanford Site is used as an example of communication challenges with different stakeholders, including Native Americans with Tribal Treaty rights to the land.

Aussie trout handle the heat

Some fishes can make themselves at home anywhere, with several species thriving in subzero Antarctica while others live in temporary tide pools. Within a single species, some populations are locally adapted to particular habitats based on what they've become accustomed to over the years. However, not all species show this flexibility. To make predictions about how fish populations will change with global warming, scientists are trying to understand which fish can adapt to the heat and why.While rainbow trout are generally thought of as a cold-water fish of the Pacific Northwest, a specific population has thrived in the desert of western Australia for almost 50 years. Isolated from their original population of the San Francisco Bay area, these fish have been used to stock natural lakes, and have undergone a few traumatic heat events during their time in Australia. More than once, summer temperature extremes have killed many fish that couldn't handle the heat, unintentionally selecting for fish with impressive upper temperature limits. Olivia Adams from the University of British Columbia, Canada, with colleagues from the same university, Harvard University, USA, the University of Western Australia and Aquatic Life Industries in Perth, Australia, wanted to investigate if a lengthy exposure to warm temperatures would improve this population's already remarkable ability to withstand extreme heat.To answer this question, the team raised groups of 1-year-old trout at six different temperatures ranging from 15 to 25°C for at least 1 month. Typically, to understand how fish cope with increased temperature, scientists focus on one or a few measures, such as growth or upper thermal limit, in a single study. But in the most comprehensive study to date, Adams and colleagues were able to look at how temperature affected the growth, energy it takes to digest a meal, physical fitness, upper temperature limit, ability to withstand low oxygen, and heart rate of these animals raised at 15, 17, 19, 21, 23 and 25°C.The Australian rainbow trout showed off their skills, with just about every aspect of their performance peaking in the groups of fish raised at 17–23°C. At these temperatures, fish had the best growth, used the least energy to digest dinner and, when exercised, were the most physically fit. These fish could even endure temperatures up to 31°C before toppling over (which is how scientists typically measure a fish's upper thermal limits). Impressively, the fish raised at 25°C were still able to grow and could also handle temperatures up to 31°C before losing their balance, but they began to struggle with digestion and fitness, and couldn't tolerate low oxygen as well as the other groups. And when the scientists tested how the fish hearts handle a brief heat exposure, they actually started to fail at 27°C, well below the temperature at which they topple over. While fish raised at 25°C show some remarkable performance in growth and increased upper thermal limits, they are noticeably limited in other ways. By using a variety of tests, Adams and colleagues presented detailed evidence that this population optimally perform at 21–23°C, which is an incredible feat when rainbow trout are thought to do best below 20°C.While clearly superstars, Australian rainbow trout aren't the only trout population that can handle the heat. Their cousins, redband rainbow trout, are geographically isolated in the desert region of the Pacific Northwest, where they regularly encounter summer temperatures between 19 and 29°C. Adams and colleagues suggest that rainbow trout may naturally carry the genes that they require to tolerate high temperatures. With a combination of artificial and natural selection, populations like the Australian rainbow trout have been able to tap into that latent heat-tolerant talent and give us a bit of hope for the future in a warming climate.

Life history of Copelatus zimmermanni Gschwendtner, 1934 (Coleoptera: Dytiscidae) and the ecological significance of the larval period of three Copelatus species

AbstractDiving beetles (Dytiscidae) play an important ecological role in most aquatic water habitats. However, approximately 40% of dytiscids in Japan have been classified as threatened, and further knowledge on their life history is necessary to support conservation efforts. In this study, we collected adult Copelatus zimmermanni (Coleoptera: Dytiscidae) from an ephemeral rain pool and raised a generation under laboratory conditions. We then compared the larval period with two Copelatus species, C. parallelus and C. masculinus. Complete development (egg to adult) occurred in 39–61 days (n = 10) and comprised the following stages: egg (3–6 days, n = 20), first instar (3–8 days, n = 20), second instar (3–12 days, n = 15), third instar larvae (4–13 days, n = 14), and landing to escape (11–36 days, n = 10). The third instar and total larval periods of C. zimmermanni were significantly shorter than those of C. parallelus and C. masculinus. The differences in the duration of larval periods may be related to the permanence of water sources used as reproductive sites for each species. We suggest that the shorter developmental period of C. zimmermanni allows it to complete entire lifecycles even in highly ephemeral aquatic habitats. This is the first report on the immature stages of a species within the C. nigrolineatus species group.

A new desiccation-resistant midge from ephemeral rock pools in South Africa, Polypedilum (Pentapedilum) cranstoni sp. nov. (Diptera: Chironomidae).

One newly described species of Chironomidae, Polypedilum (Pentapedilum) cranstoni sp. nov., was discovered in ephemeral rock pools from the Maloti-Drakensberg mountains in South Africa. Desiccation-resistant larvae were obtained from bottom sediments of rock pools that had been dry for the previous several months. After rehydration, ex situ adults emerged and were collected. The morphology and diagnostic characters of the new species (male and female adults) are described here together with an analysis based on their COI gene sequence.

Newly designed foraminifera primers identify habitat-specific lineages through metabarcoding analyses.

Foraminifera include diverse shell-building lineages found in a wide array of aquatic habitats from the deep-sea to intertidal zones to brackish and freshwater ecosystems. Recent estimates of morphological and molecular foraminifera diversity have increased the knowledge of foraminiferal diversity, which is critical as these lineages are used as bioindicators of past and present environmental perturbation. However, a comparative analysis of foraminiferal biodiversity between their major habitats (freshwater, brackish, intertidal, and marine) is underexplored, particularly using molecular tools. Here, we present a metabarcoding survey of foraminiferal diversity across different ecosystems using newly designed foraminifera-specific primers that target the hypervariable regions of the foraminifera SSU-rRNA gene (~250-300bp long). We tested these primer sets on four foraminifera species and then across several environments: the intertidal zone, coastal ecosystems, and freshwater vernal pools. We retrieved 655 operational taxonomic units (OTUs); the majority of which are undetermined taxa that have no closely matching sequences in the reference database. Furthermore, we identified 163 OTUs with distinct habitat preferences. Most of the observed OTUs belonged to lineages of single-chambered foraminifera, including poorly explored freshwater foraminifera which encompass a clade of Reticulomyxa-like forms. Our pilot study provides the community with an additional set of newly designed and taxon-specific primers to elucidate foraminiferal diversity across different habitats.

Water availability and quality determine temporal synchrony and beta diversity of microcrustaceans in temporary pools

Beta diversity patterns have been frequently used to investigate metacommunity structure. The metacommunity concept has focused primarily on the spatial beta component, but part of the unaccounted variation is likely associated with temporal beta patterns. Here, we examined the effect of seasonal variation in water availability on the spatiotemporal assembly of microcrustaceans living in temporary pools. Specifically, we sampled microcrustaceans in 5 pools monthly for 12 mo and tested how temporal fluctuations in physicochemical variables affected beta diversity. We also investigated whether species showed synchronous responses in tracking dry or wet conditions. Our study revealed that only those microcrustacean species associated with the wet season had temporally synchronous population dynamics. However, we did not find population synchrony in the dry season and in those comparisons including all microcrustacean species. Physicochemical variables such as pH, dissolved oxygen, and water transparency explained part of the spatial variation in beta diversity. These results suggest a strong influence of species sorting on metacommunity structure both in space and in time. Extreme climatic conditions, such as water scarcity, could affect population dynamics; thus, linking spatial and temporal patterns will be necessary to disentangle the effects of stochastic processes and environmental filtering on metacommunity dynamics.

High clutch failure rate due to unpredictable rainfall for an ephemeral pool-breeding frog

Animals that reproduce in temporary aquatic systems expose their offspring to a heightened risk of desiccation, as they must race to complete development and escape before water levels recede. Adults must therefore synchronise reproduction with the changing availability of water, yet the conditions they experience to trigger such an event may not relate to those offspring face throughout development, potentially leading to clutch failure. The sandpaper frog (Lechriodus fletcheri) breeds in ephemeral pools that dry within days to weeks after rainfall has ceased. We examined whether spawning frequency and offspring survival differed across two consecutive breeding seasons based on (1) rainfall at the moment of oviposition and throughout offspring development, and (2) pool volume, given their combined effect on hydroperiod. Reproduction was triggered by rainfall, with more spawn laid during periods of greater rainfall and in larger pools. While pool size was a predictor of offspring survival, rainfall during oviposition was not. Rather, follow-up rain events were required to prevent pools drying prior to metamorphosis, with rainfall evenness during development the strongest predictor of reproductive success. High clutch failure rates recorded in both seasons suggest that adults do not have the capability to predict rainfall frequency post-oviposition. We thus conclude that unpredictable rainfall leading to premature desiccation of spawning sites is the primary source of pre-metamorphic mortality for this species. Understanding the influence of rainfall predictability on offspring survival could be critical in predicting the effects of altered hydroperiod regimes due to climate change for species that exploit temporary waters.

Desiccation risk favours prevalence and diversity of tardigrade communities and influences their trophic structure in alpine ephemeral rock pools

Rock pools are ephemeral freshwater habitats characterized by their small size, well-defined boundaries, and periodic desiccation, making them ideal model systems to answer numerous ecological questions. Although there are numerous studies on rock pool fauna around the world, tardigrades have only rarely been recorded. We conducted the first tardigrade-focused study on rock pools by quantitatively extracting and classifying them from rock pools in the Italian Apennines. Rock pools were divided into three types, based on maximum duration of their inundation period. Following the patterns usually observed with rock pool invertebrates, we tested the hypothesis that desiccation has a negative effect on prevalence, abundance, and diversity of tardigrades, and thus could alter the trophic structure of their communities. In contrast to what is commonly found for other animal groups in the same type of habitat, we found that tardigrades were more diverse and prevalent in shallower, more desiccation prone, rock pools. Moreover, the trophic structure of tardigrade communities was different among the different pool types. Lastly, we also provide DNA barcodes of the most commonly found taxa. Ultimately, our study demonstrates that tardigrade communities in rock pools provide a valuable model system for the study of abiotic factors influencing meiofauna communities.

Bryophyte diversity and soil organic carbon content in contrasting Northern Appalachian vernal pools

Bryophytes are important contributors to carbon (C) sequestration and play an important role in regulating C and nitrogen (N) flux in wetland environments. We assessed bryophyte species number and biomass, and select soil chemical parameters at four depth intervals (0–5, 5–10, 10–15, and 15–20 cm) in two vernal pool systems located within two contrasting physiographic provinces (the Appalachian Plateau and the Ridge and Valley) of the U.S. northern Appalachians. Results indicated that bryophyte species number and biomass were significantly higher in the Ridge and Valley versus the Appalachian Plateau system. While total soil organic carbon (TOC) and N were significantly higher in the Ridge and Valley at the shallower depths of 0–5, 5–10, and 10–15 cm, no significant differences were found between the two physiographic provinces for either parameter at the deepest depth interval (15–20 cm). The mineral-associated fraction of soil organic C, as indicated by the recalcitrant index for C (RIC), was only found to be significantly different at the 5–10 cm depth interval. When RIC was averaged across the samples for each study area, the mineral-associated fraction of soil organic C was found to be constant with depth in all vernal pools, while the relationship between RIC and TOC varied with depth within each vernal pool. These results suggest that variations in C input due to differing bryophyte species number and biomass may explain why vernal pools in the two contrasting study areas appear to have different TOC retention capacities, yet similar potentials for long-term C sequestration.

Successive Modes of Carbonate Precipitation in Microbialites along the Hydrothermal Spring of La Salsa in Laguna Pastos Grandes (Bolivian Altiplano)

Interpreting the paleoecosystems of ancient microbialites relies on our understanding of how modern microbialites form in relation with the bio-physico-chemical conditions of their environment. In this study, we investigated the formation of modern carbonate microbialites in the hydrothermal system of La Salsa in Laguna Pastos Grandes (Bolivia), which spans a wide range of physicochemical conditions and associated microbial communities. By combining dissolved inorganic carbon (DIC) isotope mass balance modeling, analysis of carbonates solubility diagram, and imaging of the microorganisms–mineral assemblages within microbial mats, we found that several modes of carbonate precipitation dominate in distinct portions of the hydrothermal system. (1) In high-[DIC] waters, undersaturated to slightly saturated with respect to calcite, cyanobacterial calcification is promoted by CO2 degassing and photosynthetic activity within the microbial mats. (2) In alkaline waters undergoing sustained evaporation, the precipitation of an amorphous calcium carbonate phase seems to control the water a(Ca2+)/a(CO32−) ratio and to serve as a precursor to micritic calcite formation in microbial mats. (3) In saline ephemeral ponds, where the carbonate precipitation is the highest, calcite precipitation probably occurs through a different pathway, leading to a different calcite texture, i.e., aggregates of rhombohedral crystals.

Gigantic floating leaves occupy a large surface area at an economical material cost.

The giant Amazonian waterlily (genus Victoria) produces the largest floating leaves in the plant kingdom. The leaves’ notable vasculature has inspired artists, engineers, and architects for centuries. Despite the aesthetic appeal and scale of this botanical enigma, little is known about the mechanics of these extraordinary leaves. For example, how do these leaves achieve gigantic proportions? We show that the geometric form of the leaf is structurally more efficient than those of other smaller species of waterlily. In particular, the spatially varying thickness and regular branching of the primary veins ensures the structural integrity necessary for extensive coverage of the water surface, enabling optimal light capture despite a relatively low leaf biomass. Leaf gigantism in waterlilies may have been driven by selection pressures favoring a large surface area at an economical material cost, for outcompeting other plants in fast-drying ephemeral pools.

Recruitment Patterns and Potential Climate Change Impacts on Three Florida Hylids with Different Life Histories

Altered weather patterns associated with climate change are likely to adversely affect amphibian recruitment, especially for species dependent on ephemeral, geographically isolated wetlands for breeding. Future changes in temperature and rainfall patterns could affect hydroregimes (periodicity, depth, duration, and timing of water in wetlands) or adult breeding effort. We used 24 years of continuous amphibian trapping, weather, and hydroregime data to identify breeding-to-metamorphosis periods (BMPs) and environmental factors affecting annual recruitment by three hylid species at eight isolated ephemeral limesink ponds in Florida longleaf-wiregrass sandhills. We used standardized climate metrics (Bioclim variables) to predict future precipitation, temperature and hydroregime variables, then used them to predict future recruitment in 2050 and 2070 under two emissions scenarios. We hypothesized that Hyla gratiosa would be more sensitive to short-term pond drying than H. femoralis or H. squirella due to its lower abundance and more specific habitat requirements. Hyla gratiosa recruitment was not explained by adult breeding effort and was more dependent on higher water levels during BMPs than for H. femoralis or H. squirella, independent of rainfall. In contrast, H. femoralis and H. squirella recruitment depended heavily on rainfall independent of pond depth and was positively associated with adult breeding effort. Models predicted moderate decreases in H. gratiosa and H. squirella recruitment by 2050 but projections were highly uncertain for all three species by 2070. Our findings highlight the importance of maintaining wetlands with diverse hydroregimes to accommodate species with different BMPs and hydroregime requirements. Proactive monitoring and conservation measures such as headstarting and creating artificial ponds may be necessary for these and other amphibian species that may suffer reduced recruitment under future climate change.

Lack of response to pond desiccation by eggs and tadpoles of the Yungas Red-belly Toad (Melanophryniscus rubriventris) in an unpredictable environment

Anuran amphibians that breed in ephemeral ponds of unpredictable environments have mechanisms to tolerate or to avoid associated risks of egg and tadpole mortality, such as selection of oviposition sites, plasticity in larval development, and resistance of eggs to desiccation. The Yungas Red-belly Toad (Melanophryniscus rubriventris (Vellard, 1947)) breeds in temporary ponds in the Andean Yungas under unpredictable events of flooding and droughts of reproductive sites. To determine whether this species possesses any developmental mechanisms to deal with the environmental conditions, we experimentally evaluated the resistance of eggs subjected to different times of exposure to air and the tadpoles to different levels of pond desiccation. The species has not developed mechanisms of resistance of its eggs or phenotypic plasticity to the recurrent risks of pond desiccation, and mass mortality is a common event. In such a context, explosive breeding highly synchronized with rainfall, together with fast larval development, seems to be vitally important at these places where the duration of ponds is short and unpredictable.

An insight into fruit aroma volatilome during postharvest maturation in two popular Musa cultivars of tropics.

Banana is one of the major global horticultural fruit crops cultivated in the humid tropics and subtropics. Fruit quality and consumer acceptability of any climacteric fruit depend mainly on its postharvest aroma volatile profiles. The present study aimed to profile fruit volatiles status during postharvest storage of two banana cultivars: Kanthali (Musa sp. cv. Kanthali, Kt) and Kacha Kela (Musa sp. cv. Kacha Kela, Kk) from the ABB genome group. Both cultivars showed differences in the soluble sugar contents, with Kt being higher than Kk. The volatile compounds were profiled from the pulp as emitted, endogenous and glycosyl-bound forms, along with peel-endogenous and whole fruit volatiles during postharvest storage. Both cultivars showed a wide range of variations in volatile aroma pools; nevertheless, esters and aliphatic compounds were found to be the major contributors of fruit volatiles in Kt and Kk, respectively. The pulp-endogenous volatiles served as the major pool, which showed a sharp decline with a corresponding increase of emission. Many volatiles were found to be glycosylated during early postharvest storage, with de-glycosylation occurring with an increase in storage time, resulting in fruit softening and a concurrent supply of sugar bound volatiles towards emission. As a whole, the study outcome provides an overview of fruit volatilome during postharvest storage and suggests a possible inter-linking among the volatile components in the cultivars. It is plausible that the release of aroma volatiles from pulp is mediated via peel, with volatiles accumulating as peel-endogenous volatiles representing the temporary pool reservoir. © 2022 Society of Chemical Industry.

Community structure, species–habitat relationships, and conservation of amphibians in forested vernal pools in the Georgian Bay region of Ontario

Forested vernal pools serve an integral role in the recruitment of amphibians in glaciated northeastern North America. In south-central Ontario, vernal pools exist in relatively unimpacted forest networks, but the amphibian communities face uncertain challenges from anthropogenic-induced climate change. We surveyed amphibian larvae and collected measurements of habitat characteristics from vernal pools to collect baseline information on amphibian community structure and species–habitat relationships. Amphibian communities were influenced by hydroperiod length and canopy openness, and the relative abundances of early breeding amphibians were affected by changes in the structure of vegetation communities within pools. Our study suggests that, even across moderate ranges of breeding habitat characteristics, the structure of amphibian communities is dynamic. With anthropogenic-induced climate change leading to more drought-prone summers, the conservation of intact forests that support diverse wetland assemblages will be a necessary component of future legislation.

Projecting the remaining habitat for the western spadefoot (Spea hammondii) in heavily urbanized southern California

Extensive urbanization in coastal southern California has reduced natural habitat in this biodiversity hotspot. To better conserve ecological communities, state and federal agencies, along with local jurisdictions and private stakeholders, developed regional conservation plans for southern California. Although many protected areas exist within this region, the patchwork nature of these protected areas might not provide good coverage for species that require multiple habitat components, such as amphibians with complex life histories. Because of declines in the past century, the status of the western spadefoot ( Spea hammondii ) in southern California is of concern to state and federal wildlife agencies. Species distribution models (SDMs) can aid in determining the conservation status of imperiled species by projecting where suitable habitat remains and how much is protected from further development. We built SDMs that integrated site-occupancy data from systematic pitfall trapping surveys and presence-only data from biodiversity databases and citizen science platforms to project the current distribution of western spadefoots in southern California. Western spadefoot occurrence was positively related to the cover of grassland or shrub/scrub and the % sand in the soil within a 1000 m buffer, and was negatively related to slope, elevation, and distance to ephemeral streams or vernal pools. Most of the remaining unprotected habitat for western spadefoots is in the southern half of its historical range in western San Diego and Riverside counties. A few large tracts of spadefoot habitat exist on U.S. Department of Defense lands and smaller tracts remain on ecological reserves owned by state and local government agencies. Only small patches of habitat remain in the northern half of this clade’s historical range in Ventura, Orange, Los Angeles, and San Bernardino counties. Existing regional conservation plans provide ostensible spatial coverage of the majority of extant habitat for western spadefoots in southern California, but most of the habitat within the jurisdiction of these plans lacks formal protection, exposing this species to further declines as urbanization continues in the 21st century.

Statewide Prioritization of Vernal Pools for Pond-Breeding Amphibians in New Jersey

Statewide Prioritization of Vernal Pools for Pond-Breeding Amphibians in New Jersey

A new species of the seasonal killifish genus Moema (Cyprinodontiformes: Rivulidae) from the Piraí watershed in the Southwest Amazon basin

Abstract Moema, a genus of the Rivulidae family, currently comprises 20 valid species. Most of these species inhabit temporary pools in the Amazon basin and only one species is found in the upper Paraguay basin. A new member of this genus from the upper Río Madeira drainage is here described. Males of the new species differ from all congeners by the combination of a color pattern consisting of oblique, sometimes chevron-like, irregular rows of red and light blue double-dots on body; dark yellowish to golden pectoral fins with no visible markings; and a stripe pattern on the ventral section of caudal fin with a very narrow black marginal line, intermittent or even absent. The existence of infrageneric species groups within Moema, the geographic distribution and taxonomic aspects of the species present in the Ríos Mamoré and Iténez/Guaporé rivers drainages, and the observation of intraspecific aggression between males and amphibious lifestyle in the new species are discussed.

Archaeal and Bacterial Diversity and Distribution Patterns in Mediterranean-Climate Vernal Pools of Mexico and the Western USA

Biogeographic patterns in microorganisms are poorly understood, despite the importance of microbial communities for a range of ecosystem processes. Our knowledge of microbial ecology and biogeography is particularly deficient in rare and threatened ecosystems. We tested for three ecological patterns in microbial community composition within ephemeral wetlands—vernal pools—located across Baja California (Mexico) and California (USA): (1) habitat filtering; (2) a latitudinal diversity gradient; and (3) distance decay in community composition. Paired water and soil samples were collected along a latitudinal transect of vernal pools, and bacterial and archaeal communities were characterized using 16S rDNA sequencing. We identified two main microbial communities, with one community present in the soil matrix that included archaeal and bacterial soil taxa, and another community present in the overlying water that was dominated by common freshwater bacterial taxa. Aquatic microbial communities were more diverse in the north, and displayed a significant but inverted latitudinal diversity pattern. Aquatic communities also exhibited a significant distance-decay pattern, with geographic proximity, and precipitation explaining part of the community variation. Collectively these results indicate greater sensitivity to spatial and environmental variation in vernal pool aquatic microbial communities than in soil microbial communities. We conclude that vernal pool aquatic microbial communities can display distribution patterns similar to those exhibited by larger organisms, but differ in some key aspects, such as the latitudinal gradient in diversity.