Disease dynamics vary spatially and temporally in a North American amphibian

Local environmental conditions are a primary factor influencing chytridiomycosis, an emerging disease caused by the fungus Batrachochytrium dendrobatidis (Bd) that has affected over 200 amphibian species worldwide. In North America, seasonality and regional habitat differences predict considerable spatial and temporal disease variability, yet the sparse and opportunistic nature of most studies have provided insufficient data for understanding regional Bd epidemiology. We present a five-year field study that reveals spatial and temporal Bd dynamics across Lithobates yavapaiensis populations in Arizona, USA. Two populations showed no Bd infection or mortality, ten populations showed winter Bd infection, and five populations experienced winter mortality. Infection intensity decreased over winter sampling seasons, whereas mortality and infection prevalence did not change over time. Frogs dying from chytridiomycosis were significantly larger and had significantly higher infection intensities than survivors. We conclude that conserving L. yavapaiensis and other native amphibians requires protection and management of riparian ecosystems to promote populations large enough to survive winter cycles of chytridiomycosis.     

Magnitude of the US trade in amphibians and presence of Batrachochytrium dendrobatidis and ranavirus infection in imported North American bullfrogs (Rana catesbeiana)

Amphibians are globally threatened by anthropogenic habitat loss, the wildlife trade and emerging diseases. Previous authors have hypothesized that the spread of the amphibian disease chytridiomycosis (Batrachochytrium dendrobatidis) and amphibian ranaviruses are associated with the international trade in live amphibians. The North American bullfrog (Rana catesbeiana) is thought to be a carrier of these pathogens, is globally traded as a live commodity, and is sold live in US markets. We obtained importation data for all live amphibians, and parts thereof, into three major US ports of entry (Los Angeles, San Francisco and New York) from 2000 to 2005. Importation of live amphibians into these ports totaled almost 28 million individuals over this 6-year period. We collected samples from freshly-imported market frogs and found infection with both pathogens in all three cities and all seasons, with an overall infection prevalence of 62% (306/493) and 8.5% (50/588) for B. dendrobatidis and ranaviruses, respectively, by PCR. This study definitively identifies these two important pathogens in recently imported live market frogs and suggests that the amphibian trade can contribute to introductions of these pathogens into new regions. It provides support for the recent listing of B. dendrobatidis and ranaviral diseases by the OIE, and provides evidence for measures to be taken to eradicate these pathogens from the trade.     

Distribution and environmental limitations of an amphibian pathogen in the Rocky Mountains, USA

Amphibian populations continue to be imperiled by the chytrid fungus (Batrachochytrium dendrobatidis). Understanding where B. dendrobatidis (Bd) occurs and how it may be limited by environmental factors is critical to our ability to effectively conserve the amphibians affected by Bd. We sampled 1247 amphibians (boreal toads and surrogates) at 261 boreal toad (Bufo boreas) breeding sites (97 clusters) along an 11° latitudinal gradient in the Rocky Mountains to determine the distribution of B. dendrobatidis and examine environmental factors, such as temperature and elevation, that might affect its distribution. The fungus was detected at 64% of all clusters and occurred across a range of elevations (1030-3550 m) and latitudes (37.6-48.6°) but we detected it in only 42% of clusters in the south (site elevations higher), compared to 84% of clusters in the north (site elevations lower). Maximum ambient temperature (daily high) explained much of the variation in Bd occurrence in boreal toad populations and thus perhaps limits the occurrence of the pathogen in the Rocky Mountains to areas where climatic conditions facilitate optimal growth of the fungus. This information has implications in global climate change scenarios where warming temperatures may facilitate the spread of disease into previously un- or little-affected areas (i.e., higher elevations). This study provides the first regional-level, field-based effort to examine the relationship of environmental and geographic factors to the distribution of B. dendrobatidis in North America and will assist managers to focus on at-risk populations as determined by the local temperature regimes, latitude and elevation.     

The amphibian chytrid fungus along an altitudinal transect before the first reported declines in Costa Rica

Amphibian populations have declined and disappeared in protected and apparently undisturbed areas around the world, especially in montane areas of the tropics. The amphibian chytrid fungus, Batrachochytrium dendrobatidis has been implicated in many of these declines. In Costa Rica most declines occurred in the highlands. We examined an amphibian collection made in Braulio Carrillo National Park in 1986 for the amphibian chytrid fungus B. dendrobatidis, prior to the well documented amphibian declines in Monteverde, along an altitudinal transect from 100 to 2600 m elev. Skin from the pelvic patch of 202 specimens corresponding to 30 species was examined histologically to determine whether the disease was present in the highlands of the park before amphibian populations declined. For comparison, in 2002 we collected and examined 18 specimens of seven species of Eleutherodactylus and Craugastor from two other lowland Caribbean sites. The chytrid fungus was present in almost all altitudes in 1986, including lower areas. The pathogen was also found in both species that later declined and in species that did not do so. We detected chytrid fungus on amphibians collected at almost all altitudes in 1986, including those sampled at 280 m. B. dendrobatidis was abundant in frogs collected in the 2002 survey, and seems to be endemic in most of Costa Rica. More retrospective museum surveys are needed in order to determine whether it can be found in the area before 1986.     

Presence of an emerging pathogen of amphibians in introduced bullfrogs Rana catesbeiana in Venezuela

Chytridiomycosis is an emerging fungal disease of amphibians responsible for mass mortalities and population declines globally. One hypothesis for its recent emergence is anthropogenic introduction of the causative agent Batrachochytrium dendrobatidis through trade in amphibians for pets, food and biocontrol. In this study, we examined histological samples from apparently healthy American bullfrogs Rana catesbeiana that have been introduced into the Venezuelan Andes. B. dendrobatidis was present in 96% (46/48) of the individuals examined. In contrast to cases of chytridiomycosis outbreaks, the majority (44/46) of frogs had few, small lesions consistent with little or no clinical disease and no unusual mortality was observed. These findings have implications for amphibian declines in Venezuela and elsewhere. First, the high prevalence of Batrachochytrium but lack of clinical signs or chytridiomycosis-related mortality suggests that R. catesbeiana may be a good reservoir for this parasite in Venezuela. Second, the presence of this emerging pathogen in an introduced amphibian species suggests that trade and introduction of amphibians should be monitored and controlled to halt the spread of this pathogen nationally and internationally.     

Removal of nonnative fish results in population expansion of a declining amphibian (mountain yellow-legged frog, Rana muscosa)

The mountain yellow-legged frog (Rana muscosa) was once a common inhabitant of the Sierra Nevada (California, USA), but has declined precipitously during the past century due in part to the introduction of nonnative fish into naturally fishless habitats. The objectives of the current study were to describe (1) the effect of fish removal from three lakes (located in two watersheds) on the small, remnant R. muscosa populations inhabiting those lakes, and (2) the initial development of metapopulation structure in each watershed as R. muscosa from expanding populations in fish-removal lakes dispersed to adjacent habitats. At all three fish-removal lakes, R. muscosa population densities increased significantly following the removal of predatory fish. The magnitude of these increases was significantly greater than that observed over the same time period in R. muscosa populations inhabiting control lakes that remained in their natural fishless condition. Following these population increases, R. muscosa dispersed to adjacent suitable (but unoccupied) sites, moving between 200 and 900 m along streams or across dry land. Together, these results suggest that large-scale removal of introduced fish could result in at least partial reversal of the decline of R. muscosa. Continued monitoring of R. muscosa at the fish-removal sites will be necessary to determine whether the positive effects of fish eradication are sustained over the long-term, especially in light of the increasingly important role played by an emerging infectious disease (chytridiomycosis, caused by Batrachochytrium dendrobatidis) in influencing R. muscosa populations.     

The recent decline of a New Zealand endemic: how and why did populations of Archey's frog Leiopelma archeyi crash over 1996-2001?

Dramatic changes have been documented in New Zealand's vertebrate faunas since human settlement, involving major declines and extinctions, but over recent years few species have declined in numbers so rapidly as the terrestrial Archey's frog Leiopelma archeyi (Anura: Leiopelmatidae). Long-term monitoring over more than 20 years revealed a major population reduction of the species over 1996-2001 and L. archeyi is now classified as Nationally Critical under the New Zealand threat classification system. The decline progressed northwards in the Coromandel ranges, and mostly larger (female) frogs survived. On a 100 m² study plot at Tapu Ridge, annual population estimates averaged 433 frogs (SE ±32) over 1984-1994, declining by 88% to average 53 frogs (SE ±8) over 1996-2002. A mean annual survival rate of 82% for most years declined to 33% over 1994-1997. There is mounting evidence to suggest that disease is the major agent of decline, supported by (1) the rapidity and severity of decline, (2) the progressive (south to north) nature of decline, and (3) finding frogs with chytriodiomycosis from Batrachochytrium dendrobatidis at the time of decline. Surprisingly, sympatric populations of the semi-aquatic Leiopelma hochstetteri have not declined dramatically, nor has a western population of L. archeyi at Whareorino, despite chytridiomycosis occurring in some frogs there. Sustaining and restoring populations of L. archeyi in New Zealand raises major challenges for conservation management.     

Infection of an invasive frog Eleutherodactylus coqui by the chytrid fungus Batrachochytrium dendrobatidis in Hawaii

The chytrid fungus Batrachochytrium dendrobatidis has contributed to declines and extinctions of amphibians worldwide. B. dendrobatidis is known to infect the frog Eleutherodactylus coqui in its native Puerto Rico. E. coqui was accidentally introduced into Hawaii in the late 1980s, where there are now hundreds of populations. B. dendrobatidis was being considered as a biological control agent for E. coqui because there are no native amphibians in Hawaii. Using a DNA-based assay, we tested 382 E. coqui from Hawaii for B. dendrobatidis and found that 2.4% are already infected. We found infected frogs in four of 10 study sites and on both the islands of Hawaii and Maui. This is the first report of B. dendrobatidis in wild populations in Hawaii. As the range of E. coqui expands, it may become a vector for the transmittance of B. dendrobatidis to geographic areas where B. dendrobatidis does not yet exist.     

Invasive shrub alters native forest amphibian communities

Although invasive plants can have transformative effects on native plant communities, studies of the consequences of plant invasion for native fauna are generally restricted to primary consumers. Here we investigate whether an invasive shrub, Lonicera maackii, impacts native amphibians and evaluate evidence for the role of invasive plant-induced alteration of forest understory microclimate as a mechanism driving amphibian responses to L. maackii invasion. We sampled amphibian communities in forest plots with high or low density of L. maackii, and monitored microclimate (temperature and humidity at ground level) in the same forest plots. Amphibian species richness and evenness were lower in invaded plots. Invasion also resulted in shifts in amphibian species composition. Mean daily maximum temperature and mean daily temperature were lower in invaded plots, and counts of the Green frog Lithobates clamitans were marginally negatively related to mean daily temperature. Our work illustrates how an invasive ecosystem engineer may affect native organisms with which it shares no trophic connection, and suggests that changes in microclimate may be one mechanism by which alien plants affect communities where they invade.     

Proportion of individuals with anti-Batrachochytrium dendrobatidis skin bacteria is associated with population persistence in the frog Rana muscosa

The emergence of the infectious disease chytridiomycosis is a major factor responsible for amphibian extinctions in pristine habitats. However, some populations coexist with Batrachochytrium dendrobatidis (Bd), the agent of chytridiomycosis, and others go extinct when Bd arrives. Variation of pathogen severity among populations may be explained by differences of antimicrobial skin peptides and anti-Bd skin bacteria. Previous work showed that a population of the frog Rana sierrae had a high proportion of individuals with at least one species of cultured anti-Bd skin bacteria and was coexisting with Bd for more than 6 years. A population of the closely related sister species Rana muscosa had a significantly lower proportion of individuals with anti-Bd bacteria, and the following year, it went extinct due to Bd. We extended previous work to include another sampling of the R. sierrae population coexisting with Bd and found that, although the anti-Bd bacterial community somewhat differed, both populations had a high proportion of individuals with antifungal bacteria. We also included a population of R. muscosa that was naïve of Bd and predicted to go extinct once Bd emerged since that was the fate of neighboring populations. However, the naïve R. muscosa population had a high proportion of antifungal bacteria, which suggested that the population might survive if Bd emerged. Two years later, the population was surviving with Bd endemic. Variation in the proportion of individuals with anti-Bd skin bacteria appears to explain why some populations persist when Bd emerges in a population.     

The genetic structure of coastal giant salamanders (Dicamptodon tenebrosus) in a managed forest

The salamander, Dicamptodon tenebrosus, is threatened by habitat loss and fragmentation associated with forest harvest activities. We used three microsatellite loci and 38 amplified fragment length polymorphisms (AFLPs) to quantify population structure and indirectly evaluate the impacts of forest harvesting on this species. We sampled two old growth sites, three second growth sites and three recently clearcut sites in British Columbia, Canada. Microsatellite allelic richness and the percentage of polymorphic AFLPs were positively correlated with the age of forest stands. Similarly, heterozygosity estimated from both marker types was positively correlated with stand age. Population subdivision (F_st) estimated among forested sites using microsatellite and AFLP markers was 0.033 and 0.095, respectively. Lower genetic variation and heterozygosity in recent clearcuts suggest that clearcut logging may be associated with local population declines. Our genetic findings are consistent with previous studies that report lower salamander densities in recently clearcut sites.     

Population decline of northern dusky salamanders at Acadia National Park, Maine, USA

We investigated and reviewed the current and historic distribution of northern dusky salamanders (Desmognathus fuscus fuscus) in Acadia National Park (ANP), Maine, USA during 1938-2003. Historical data indicate that northern dusky salamanders were once widespread and common in ANP. We conducted intensive surveys for stream salamanders during 2000-2003 and observed only two adult northern dusky salamanders on one stream. No eggs or larvae were observed. Although the cause of the observed population decline is unknown, we identify multiple potential stressors including stocking of predatory fishes, fungal pathogens, substrate embeddedness, and widespread pollution (i.e., from atmospheric pollutants) of surface waters at ANP. Our data suggest that ANP streams may no longer be suitable for northern dusky salamanders. This investigation is the first to document the decline of a stream dwelling amphibian species in a national park (i.e., areas that are not subject to obvious habitat loss or major changes in land use) with widespread mercury contamination of its surface waters.     

Suppressiveness of 18 composts against 7 pathosystems: Variability in pathogen response

Compost is often reported as a substrate that is able to suppress soilborne plant pathogens, but suppression varies according to the type of compost and pathosystem. Reports often deal with a single pathogen while in reality crops are attacked by multiple plant pathogens. The goal of the present study was to evaluate the disease suppression ability of a wide range of composts for a range of plant pathogens. This study was conducted by a consortium of researchers from several European countries. Composts originated from different countries and source materials including green and yard waste, straw, bark, biowaste and municipal sewage. Suppressiveness of compost-amended (20% vol./vol.) peat-based potting soil was determined against Verticillium dahliae on eggplant, Rhizoctonia solani on cauliflower, Phytophthora nicotianae on tomato, Phytophthora cinnamomi on lupin and Cylindrocladium spathiphylli on Spathiphyllum sp., and of compost-amended loamy soil (20% vol./vol.) against R. solani on Pinus sylvestris and Fusarium oxysporum f. sp. lini on flax. From the 120 bioassays involving 18 composts and 7 pathosystems, significant disease suppression was found in 54% of the cases while only 3% of the cases showed significant disease enhancement. Pathogens were affected differently by the composts. In general, prediction of disease suppression was better when parameters derived from the compost mixes were used rather than those derived from the pure composts. Regression analyses of disease suppression of the individual pathogens with parameters of compost-amended peat-based mixes revealed the following groupings: (1) competition-sensitive: F. oxysporum and R. solani/cauliflower; (2) rhizosphere-affected: V. dahliae; (3) pH-related: P. nicotianae; and (4) specific/unknown: R. solani/pine, P. cinnamomi and C. spathiphylli. It was concluded that application of compost has in general a positive or no effect on disease suppression, and only rarely a disease stimulating effect.     

Recent, substantial, and unexplained declines of the common toad Bufo bufo in lowland England

A decline in numbers of a large common toad (Bufo bufo) population in south-east England during the 1990s, together with anecdotal reports of similar trends in other toad populations, prompted a nation-wide survey of this species. The survey also included the common frog (Rana temporaria) as a control for which there was no comparable evidence of recent decline. A questionnaire requesting information on the fate of toad and frog populations in the last 15 years of the 20th century was distributed to professional and amateur herpetologists during autumn 2001. Ninety-five respondents provided data on a total of 277 sites, including 232 frog and 202 toad populations in England, Scotland and Wales. More than 80% of the reported sites were rural for both species. Rural frog populations were generally doing well in most parts of Britain, with almost as many increasing as decreasing populations and a high proportion of stable populations. Rural toads also showed no overall trend across the country as a whole. However, regional analysis indicated that although toads were faring at least as well as frogs in the north and west of Britain, they were declining seriously in central and eastern/south-eastern areas. In these regions 50% or more of toad populations have experienced recent declines, whereas frogs have fared as well as they have elsewhere. Toads breeding alone have fared significantly worse than toads breeding at sites where frogs were also present. Reasons for apparently toad-specific declines in lowland England remain unknown.     

Seagrass on the edge: Land-use practices threaten coastal seagrass communities in Sabah, Malaysia

Seagrass meadows are susceptible to coastal environmental impacts and serve as early indicators of system-wide degradation. Two SeagrassNet monitoring sites were established in Sabah (Malaysia) in 2001 in the Tunku Abdul Rahman National Park: one a pristine, reference site and one anticipating impacts from nearby, ongoing waterfront development. At both sites, percent cover of all seagrass species declined significantly between 2003 and 2005. Water temperature, fine sediment and specific leaf biomass increased, while percent surface light intensity reaching the plants decreased. Evidence suggests that the temperature changes observed during the monitoring period were not sufficient to impact seagrasses; rather, the documented reduced subsurface light intensity caused the observed seagrass declines. Concomitantly, satellite imagery revealed a persistent sediment plume in these coastal waters associated with deforestation. SeagrassNet monitoring quickly documented seagrass losses and identified the causal environmental factor, providing timely information for management consideration.     

Overwintering management on upland pasture causes shifts in an abundance of denitrifying microbial communities, their activity and N2O-reducing ability

Pasture soils used for cattle overwintering may represent significant sources of N₂O emissions from soils. Therefore, the long-term effect of cattle overwintering on the abundance and activity of a denitrifying community was explored. The study was performed at a cattle overwintering area in South Bohemia (Czech Republic), where three sites differing in the degree of animal impact were selected: severely impacted (SI) and moderately impacted (MI), as well as a control site with no impact (NI). N₂O flux measurement and soil sampling were performed in spring and fall of 2005. The activity was measured in terms of potential denitrification activity. Bacterial nirK, nirS and nosZ genes were used as functional markers of the denitrifying communities; abundance was analyzed using a real-time PCR assay. Surprisingly, in situ N₂O emissions were the highest in spring at MI and significantly differed from those at SI and NI, while in autumn, rates of emissions generally decreased. In contrast potential denitrification rates were highest at SI, followed by MI, and the lowest at NI. An overall significant shift in N₂O/N₂ molar ratio was shown in cattle impacted sites. The highest abundance of all genes measured at both sampling times was found at site SI, whereas at site MI increased numbers were observed only in spring. Our results indicate a strong influence of cattle on the abundance as well as the activity of microbes involved in denitrification.     

Factors related to the distribution and prevalence of the fungal pathogen Batrachochytrium dendrobatidis in Rana cascadae and other amphibians in the Klamath Mountains

The fungal pathogen Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis, has been associated with declines and extinctions of montane amphibians worldwide. To gain insight into factors affecting its distribution and prevalence we focus on the amphibian community of the Klamath Mountains in northwest California. The Cascades frog (Rana cascadae), one of the most common amphibians in these mountains, experienced increased mortality as a result of Bd exposure in laboratory trials and has experienced recent, dramatic declines in other parts of California. We surveyed 112 sites in the Klamaths, all of which supported R. cascadae between 1999 and 2002, for amphibians and Bd to (1) determine the distribution of Bd, (2) evaluate changes in the distribution of R. cascadae, and (3) assess associations between potential biotic and abiotic drivers and Bd infection. Bd was widely distributed in the Klamath Mountains – we detected the pathogen at 64% of sites. R. cascadae was found at 79% of sites, and was often infected with Bd. These results suggest that Bd has not caused dramatic declines in R. cascadae in the Klamaths in recent years. Subadult R. cascadae had a higher Bd prevalence than other R. cascadae life stages (subadults: 36%, adults: 25%, metamorphs: 4%, larvae: 1%), and while the probability of infection decreased over the season for adults, it did not for subadults, suggesting that subadults may be more vulnerable to chytridiomycosis than other R. cascadae life stages. Bd prevalence in R. cascadae was highest early in the season at high-elevation sites, which may indicate that populations inhabiting high elevation sites may have a greater risk of being affected by chytridiomycosis. Three other common amphibian species also tested positive for Bd: Pacific chorus frog (Pseudacris regilla), western toad (Anaxyrus boreas), and rough-skinned newt (Taricha granulosa).     

Functional diversity of microbial communities in the mixed boreal plain forest of central Canada

This study was designed to examine whether or not specific tree species (Picea glauca, Picea mariana, Pinus banksiana, Populus tremuloides), their post-fire stand age, or their position in a successional pathway had any significant effect on the functional diversity of associated soil microbial communities in a typical mixed boreal forest ecosystem (Duck Mountain Provincial Forest, Manitoba, Canada). Multivariate analyses designed to identify significant biotic and/or abiotic variables associated with patterns of organic substrate utilization (assessed using the BIOLOG™ System) revealed the overall similarity in substrate utilization by the soil microbial communities. The five clusters identified differed mainly by their substrate-utilization value rather than by specific substrate utilization. Variability in community functional diversity was not strongly associated to tree species or post-fire stand age; however, redundancy analysis indicated a stronger association between substrate utilization and successional pathway and soil pH. For example, microbial communities associated with the relatively high pH soils of the P. tremuloides-P. glauca successional pathway, exhibited a greater degree of substrate utilization than those associated with the P. banksiana-P. mariana successional pathway and more acidic soils. Differences in functional diversity specific to tree species were not observed and this may have reflected the mixed nature of the forest stands and of their heterogeneous forest floor. In a densely treed, mixed boreal forest ecosystem, great overlap in tree and understory species occur making it difficult to assign a definitive microbial community to any particular tree species. The presence of P. tremuloides in all stand types and post fire stand ages has probably contributed to the large amount of overlap in utilization profiles among soil samples.     

The effect of habitat fragmentation on communities of mutualists: Amazonian ants and their host plants

The consequences of fragmentation for communities of mutualist partners are for the most part unknown; moreover, most studies addressing this issue have been conducted on plant-pollinator communities. We evaluated how the experimental fragmentation of lowland Amazonian rain forest influenced a community of ant-plant mutualists. We inventoried a total of 1057 myrmecophytes in four fragments and four continuous forest sites; the twelve plant species recorded were occupied by 33 ant morphospecies, of which 11 were obligate plant inhabitants. Neither plant species richness, ant species richness, nor total ant-plant density were significantly lower in forest fragments. However, eight of the plant species, including three of the four most common, had higher mean densities in continuous forest than fragments. Of these four species, only one (Cordia nodosa) had significantly different colonization rates between habitat types, with higher colonization rates of plants in fragments. This may be because the Azteca species it is associated with increases in abundance in forest isolates. Although our results suggest that communities of ant-plant mutualists are likely to persist in fragmented tropical landscapes 25 years after fragment isolation, most species are rare and populations sizes in fragments are extremely low. Environmental and demographic stochasticity could therefore limit long-term population viability. We suggest future studies focus on evaluating how fragmentation has altered herbivore pressure and the dispersal of ants and plants to fragments, since the interaction of these factors is likely to have the greatest impact on long-term patterns of population persistence.     

Effects of increased salinity and an introduced predator on lowland amphibians in Southern China: Species identity matters

Approximately 30% of amphibian species are threatened due to a variety of factors affecting their habitats and physiology, yet contributions that interactions among factors make to population declines are not well-explored. Two factors, introduced mosquitofish (Gambusia affinis) and increased salinity, may coincide in lowland habitats used by breeding amphibians. Mosquitofish have been introduced worldwide and can be significant predators of amphibian larvae. Salinization of wetlands is an increasing problem globally due to (1) application of road deicing salts in temperate regions, (2) irrigation practices associated with intensive agriculture, and (3) saltwater intrusion due to sea-level rise. We investigated the effects of mosquitofish (G. affinis) and increasing salinity on five species of lowland wetland-breeding amphibians from southern China. We exposed anuran hatchlings to four salinity levels and two fish treatments and all combinations of the two factors in a series of experiments. Four of the species were susceptible to predation by mosquitofish, two were sensitive to increased salinity at concentrations >6% seawater, and one was tolerant of both increased salinity and mosquitofish. We found no interaction between the predator and increased salinity. Salinization and mosquitofish represent significant threats to lowland amphibians in this region and, coupled with the ongoing loss and degradation of lowland wetlands, portend a bleak future for lowland amphibian populations in the region.