Abundance Of Ponds Research Articles

Structural and functional differences of gut microbiota in Pomacea canaliculata from different geographical locations and habitats.

Gut microbiota is related to host fitness, and influenced by geographical locations and habitats. Pomacea canaliculata is a malignant invasive alien snail that threatens agricultural production and ecosystem functions worldwide. Clarifying the general rules of the gut microbial community structure and function of the snails in different geographical locations and habitats is of great significance for understanding their invasion at different spatial scales. This study used high-throughput sequencing technology to compare and analyze the differences in community structure and function of gut microbiota in P. canaliculata from five geographical locations (Liuzhou, Yulin, Nanning, Wuzhou, and Hezhou) and three different habitats (pond, paddy field, and ditch) in Guangxi Province. The results showed that intestinal microbial alpha diversity of P. canaliculata was higher in Liuzhou, Yulin, lower in Nanning, Wuzhou, Hezhou, and higher in ponds compared with paddy fields and ditches. The dominant phyla of gut microbiota in snails were Firmicutes, Cyanobacteria, Proteobacteria, Fusobacteriota, Bacteroidota, and the dominant genus was Lactococcus. The community structure of gut microbiota in snails varied significantly across different geographical locations and habitats, and the phyla Firmicutes, Cyanobacteria had significantly higher relative abundance in snails collected from Nanning and Yulin, respectively. Moreover, the relative abundance of gut functional microbiota associated with human disease in P. canaliculata was significantly affected by geographical locations and habitats, and with the highest abundance in ponds. However, the relative abundance of functional microbiota related to metabolism, genetic information processing, organizational system, environmental information processing, and cellular processes were only significantly affected by geographical locations. Collectively, geographical locations and habitats had significantly different effects on the community structure and function of gut microbiota in P. canaliculata, and the greater differences were caused by geographical locations rather than by habitats.

Groundwater decline has negatively affected the well-preserved amphibian community of Doñana National Park (SW Spain)

Abstract The success of amphibian conservation efforts is highly dependent on the preservation of amphibian breeding habitats. Doñana National Park contains an abundance of ponds with heterogeneous characteristics, which has historically favoured its amphibian community. However, most of the park’s ponds are groundwater dependent, and aquifer overexploitation outside the park is leading to shorter hydroperiods and even desiccation in the pond network. This problem has been exacerbated by the scarcity of rain over the last decade. In 2021-2022, we surveyed the occurrence of the park’s 11 amphibian species, with a view to comparing our findings with those from the last previous survey in 2003-2004. We mapped the species occurrence within the park for the two survey periods. While all 11 amphibian species could still be found in Doñana, their occurrence had decreased across the board. In 2003-2004, 6 species were present across more than 50% of the sampling area. In contrast, 18 years later, such was the case for only two species (Pelophylax perezi and Hyla meridionalis). Declines were greatest for Epidalea calamita, followed by Pelobates cultripes, Triturus pygmaeus, and Lissotriton boscai. The mean number of species per sampling unit (i.e., grid cell) dropped from 4.3 to 3.1. To preserve Doñana’s amphibian community, it is important to restore the park’s pond network, which implies reducing regional groundwater overexploitation.

Effects of urbanization, biotic and abiotic factors on aquatic insect diversity in urban ponds

Urbanization leads to drastic modifications of the terrestrial and aquatic environment. However, urban ponds may provide valuable habitats for different taxa, including aquatic insects and amphibians. We aim to understand how a set of biotic and abiotic factors influence aquatic insect diversity in 18 urban ponds in the German metropolis Berlin, one of the greenest whilst most densely populated European cities. Greenspace is important for the terrestrial stages of some aquatic insects and amphibians, providing crucial resources. Thus, greenspace was assumed to have positive effects on aquatic insect diversity, whereas built-up area was assumed to affect diversity negatively. Because some aquatic insects prey on tadpoles, their abundance and diversity were assumed to depend on tadpole abundance, which in turn, depends on other food (i.e., phytoplankton) availability in ponds. We visited the ponds twice a year, in spring and summer, and collected data on aquatic insects that are known to prey on tadpoles, tadpole abundance, phytoplankton biomass, the presence or absence of large insect predators, as well as physical–chemical parameters. We assumed higher total aquatic insect abundance, genera richness, alpha-diversity, and evenness, as well as abundance and genera richness of different aquatic insect taxonomic groups to be associated with high tadpole abundance in ponds surrounded by high amount of greenspace and low levels of built-up area. Accordingly, we expected aquatic insects to be modulated by phytoplankton biomass, the presence of newts and fish, and to be affected by ponds’ abiotic conditions. Our results showed that biological interactions and abiotic water conditions override urban effects in ponds’ terrestrial surroundings on aquatic insect diversity levels, whereas aquatic insects’ taxonomic groups responded differently on different land-use types around ponds. We explain our findings due to different dependences and demands towards terrestrial and/or aquatic habitats by different taxonomic groups of aquatic insects, and differences in their colonization behavior.

PHYTOPLANKTON COMMUNITY IN VANNAMEI SHRIMP (Litopenaeus vannamei) CULTIVATION IN INTENSIVE PONDS

Optimal growth of shrimp and harvest in a pond is strongly influenced by water quality because this is a common thing but it cannot be denied that it is also an important thing. The combination of physicochemical parameters and biological indicators has become a classic way of studying water quality. Phytoplankton is a bioindicator that affects the productivity of vannamei shrimp in ponds. Currently, shrimp farming activities are intensive. This study aimed to analyze the diversity and abundance of phytoplankton and water quality in vannamei shrimp ponds. The research objective was achieved by calculating the abundance, diversity index, evenness index, and plankton dominance index in ponds. The results of the study were that the phytoplankton of Chlorophyta with the highest total abundance in each pond was 18,400x103 ind/l, 14,900x103 ind/l, 16,620x103 ind/l, and 6.410x103 ind/l. The index of phytoplankton diversity at each location was 0.74, 0.73, 0.87, 0.74. Phytoplankton uniformity index at each location was 0.04, 0.04, 0.05, 0.05. Phytoplankton dominance index at each location was 0.60, 0.38, 0.56, 0.07. The abundance of phytoplankton is an obstacle to the success of vannamei shrimp aquaculture production.

Fluctuation Effect of Dissolved of TAN (Total Ammonia Nitrogen) on Diatom Abundance in Intensive Shrimp Culture Ponds

TAN (Total Ammonia Nitrogen) is the accumulation of nutrient elements needed by plankton to grow in intensive shrimp farming ponds. The purpose of this study was to determine the relationship effect of TAN concentration fluctuations on diatom abundance in the intensive shrimp culture cycle. This research was conducted during one intensive shrimp culture cycle at PT. Menjangan Mas Nusantara, Pandeglang, with its research variables is the dominance percentage of plankton abundance and the level of TAN solubility in ponds. The results showed that during the shrimp culture period the abundance of plankton was dominated by predominant diatom, chlorophyceae, and chyanophyceae classes. The percentage of diatom dominance during cultivation has a graph similarity with the level dissolved of TAN fluctuation in the pond. The dissolved of TAN itself is described continue to increase with shrimp farming age. Statically, the relationship between the dissolved effect of TAN concentration on diatom abundance in ponds was modeled by the regression equation y = 2.210 + 32.411 (R2= 0.88; α0.00). The conclusion obtained from the results of this study, the level of dominance by diatom abundance during shrimp culture period is strongly influenced by the fluctuation of TAN concentration as the main nutrient element in ponds with a significance level of 88%.

Occurrence of microplastics in a pond-river-lake connection water system: How does the aquaculture process affect microplastics in natural water bodies

Aquaculture activities have been considered to be important sources of microplastics to the water. Microplastic contamination closely related to aquaculture activities has been found in mariculture areas as well as in there nearby natural water bodies. However, for freshwater bodies with complex connectivity, it remains to be revealed how aquaculture activities affect microplastics in neighboring natural water bodies. In this study, we investigated the occurrence of microplastics of a water system consisting of aquaculture ponds, rivers, and lakes in June and December, which represented different aquaculture stages. The average microplastic abundances in June were 167 (67–367) items/m3, 129 (67–233) items/m3, and 372 (100–1167) items/m3, respectively in the lake, river, and aquaculture ponds, while in December, those were 533 (200–933) items/m3, 311 (200–600) items/m3, and 429 (200–600) items/m3, respectively. Microplastic abundance in ponds was significantly higher than in the river in June, while there was no significant spatial difference of microplastic abundance in December. Microplastics abundances in both river and lake were significantly higher in December than in June. The characteristics of morphology, size, color, and polymer type of microplastics were also different among different water bodies in June. However, the differences became smaller in December. The results of this study implied that the drainage of aquaculture ponds might increase the microplastics abundances of natural water in the water system predominated by aquaculture ponds. Further studies of the environmental fate of microplastics in ponds would be beneficial for understanding and controlling microplastics in the whole water system.

Fish abundance estimation with imaging sonar in semi-intensive aquaculture ponds

To know the abundance of fishes and their size distribution in the semi-intensive rearing systems in traditional ponds is an aspect key to plan and manage efficiently the sales lots. Usually this information is obtained by means of sampling which mandatory supposes a direct catch and stressful and time consuming management of fishes. Therefore, in this work we propose the use of non-invasive procedures based on multibeam sonars or imaging sonars to count and size the fishes in the ponds. For that, we use a commercial technology portable-fixed multibeam imaging sonar and estimate the abundance in ponds of a gilt-head seabream (Sparus aurata) fishfarm from sonar image analysis and adapting statistical methodologies traditionally applied for bird abundance estimation. Additionally, a simulation software was developed to emulate the fish aggregation contained in the rearing ponds. This computer program allows the calculation of an abundance correction factor which depends on the transducer beam size in relation to the pond size. The results indicate that the estimation is as accurate as the obtained by the fishfarm manager using traditional sampling methods and additionally it is possible to obtain a realistic function of the size distribution which allows estimate the biomass by size contained in the rearing ponds.

Roads reduce amphibian abundance in ponds across a fragmented landscape

Roads threaten animal species through habitat loss, fragmentation and degradation, and direct mortality. It is crucial to understand how species respond to linear infrastructure for effective conservation of animal communities in fragmented landscapes. We assessed relationships between amphibian abundance and roads/ railways and habitat fragmentation. We examined whether the combined effects of habitat loss and roads or railways (accessible habitat) was a better predictor of amphibian abundance than (1) the total amount of habitat surrounding ponds, (2) distance to a highway or railway, or (3) surrounding road cover. Aquatic surveys for amphibian larvae were conducted at 30 freshwater ponds over the breeding season in a mixed peri-urban/ agricultural landscape in Hungary. Landscape variables were quantified within a 1000-m radius surrounding ponds and habitat variables were measured at the local (pond) scale. The larvae of seven amphibian species were detected. There were strong relationships between the abundance of amphibian larvae and the distance to a highway and the proportion of road cover within 1000 m of ponds. Relationships with accessible habitat and total habitat amount were uncertain, while there were no clear relationships with a major railway. Larval abundance increased with pond size, but there were mixed relationships with the presence of fish. Our results suggest that road effects were having a stronger impact on amphibian abundance than the combined effects of roads and habitat amount in the study area. Highways appeared to be negatively impacting amphibian communities within a wide road-effect zone up to 1 km from ponds. However, our results were obtained from a single-season snap-shot study and multi-season surveys are likely required to reduce uncertainty in the model predictions. Our analysis suggests that road mitigation projects for amphibians should create large ponds in areas with no highways and low road density, and with connectivity to surrounding habitats.

Pre-fledging quality and recruitment in an aerial insectivore reflect dynamics of insects, wetlands and climate.

Wetland systems, including shallow palustrine ponds, are hotspots for emergent aquatic insects but are globally threatened by land-use practices and climate change. Loss of insects is hypothesized as a key driver of population declines in aerial insectivores, but studies of climate-driven fluctuations in pond abundance during wet-dry periods and aerial insects on nestling quality and apparent recruitment are lacking. Using tree swallow (Tachycineta bicolor) data spanning 14-28years we evaluated: (1) whether nestling quality based on pre-fledging (~ 12days old) body mass changed over the time series; (2) how annual estimates of aerial insect biomass and variability, temperature, and pond abundance influenced nestling mass; and (3) whether the annual number of recruits produced was related to the annual mean mass of nestlings, aerial insects, and pond abundance in their year of hatching. Average nestling body mass varied annually but no long-term temporal trends were detected. Nestlings were heavier when raised during periods of stable insect biomass, warmer temperatures, and higher pond abundance. Pond abundance consistently had strong effects on nestling mass and inter-annual apparent recruitment, suggesting that this metric provides a complementary index of either higher prey abundance or higher-quality aquatic prey. Overall, pre-fledging quality and annual recruitment of nestling tree swallows reflects dynamic interannualchanges in climate, pond availability, and aerial insect food supply. Our findings further suggest the abundance of ponds in this semi-arid prairie landscape is likely a strong predictor of regional population stability in tree swallows and possibly other ecologically similar species.

Quantifying organic carbon storage in temperate pond sediments

Ponds may hold significant stocks of organic carbon in their sediments and pond creation may offer a practical application for land managers to increase carbon storage. However, ponds are overlooked in global carbon budgets. Their potential significance is suggested by the abundance of ponds throughout terrestrial biomes and their high carbon burial rates, but we lack measures of sediment carbon stocks from typical ponds. We sampled sediment from lowland temperate ponds in north east England comparing carbon stocks from ponds categorised by surrounding land use, or dominant vegetation, or drying regime, along with measures of variation within ponds. Sediment carbon varied considerably between ponds. This variation was more important than any systematic variation between pond types grouped by land use, vegetation or drying, or any variation within an individual pond. Our estimates of pond sediment organic carbon give measures that are higher than from soils in widespread habitats such as temperate grassland and woodland, suggesting that ponds are significant for carbon budgets in their own right. Ponds are relatively easy to create, are ubiquitous throughout temperate biomes and can be fitted in amongst other land uses; our results show that pond creation would be a useful and practical application to boost carbon sequestration in temperate landscapes.

The Discovery of Vibrio harveyi on Litopenaeus vannamei Infected White Feces Disease in Situbondo, East Java

This research was conducted to discover Vibrio harveyi infected vannamei shrimp with White Feces Disease (WFD) in Situbondo, East Java Province. This research was conducted in November 2017 until September 2018. All Vibrio isolates from shrimp infected WFD were identified with biochemical tests, Analytical Profile Index/ API 20NE (BioMeriuex), and PCR with specific primers for V. harveyi. Additional parameters were the water quality, plankton brackishwater pond abundance, and antibiotic resistance test. Result showed that from 17 bacterial isolates identified, 10 isolates were V. harveyi (58.82%), three isolates were V. alginolyticus (17.65%), one V. fluvialis isolate (5.88%), one V. parahaemolyticus isolate (5.88%), and two non Vibrio isolates which were identified as Shewanella putrefaciens (11.76%). All isolates of V. harveyi also showed resistance activity on more than one antibiotic. Poor water quality had been identified as abnormal result of pH, alkalinity, salinity, ammonia levels and total organic matter level. Plankton abundance observation showed that Chloropyceae, Diatom, and Dinoflagellata dominated all sampled brackishwater ponds. This research concluded that V. harveyi were discovered on vannamei shrimp with poor water quality and plankton abundance in the pond samples.

Network‐scale effects of invasive species on spatially‐structured amphibian populations

Understanding the factors affecting the dynamics of spatially‐structured populations (SSP) is a central topic of conservation and landscape ecology. Invasive alien species are increasingly important drivers of the dynamics of native species. However, the impacts of invasives are often assessed at the patch scale, while their effects on SSP dynamics are rarely considered. We used long‐term abundance data to test whether the impact of invasive crayfish on subpopulations can also affect the whole SSP dynamics, through their influence on source populations. From 2010 to 2018, we surveyed a network of 58 ponds and recorded the abundance of Italian agile frog clutches, the occurrence of an invasive crayfish, and environmental features. Using Bayesian hierarchical models, we assessed relationhips between frog abundance in ponds and a) environmental features; b) connectivity within the SSP; c) occurrence of invasive species at both the patch‐ and the SSP‐levels. If spatial relationships between ponds were overlooked, we did not detect effects of crayfish presence on frog abundance or trends. When we jointly considered habitat, subpopulation and SSP features, processes acting at all these levels affected frog abundance. At the subpopulation scale, frog abundance in a year was related to habitat features, but was unrelated to crayfish occurrence at that site during the previous year. However, when we considered the SSP level, we found a strong negative relationship between frog abundance in a given site and crayfish frequency in surrounding wetlands during the previous year. Hence, SSP‐level analyses can identify effects that would remain unnoticed when focussing on single patches. Invasive species can affect population dynamics even in not invaded patches, through the degradation of subpopulation networks. Patch‐scale assessments of the impact of invasive species can thus be insufficient: predicting the long‐term interplay between invasive and native populations requires landscape‐level approaches accounting for the complexity of spatial interactions.

KONDISI PLANKTON PADA TAMBAK UDANG WINDU (Penaeus monodon FABRICIUS) DENGAN SUBSTRAT BERBEDA

Plankton is one of water microorganisms that plays an important role as natural food for fish and shrimp and as an stability indicator of water or aquatic environment.The purpose of this study was to determine the composition and abundance of plankton in tiger shrimp ponds using concrete ponds without substrate, concrete ponds using sand substrate and ponds. Sampling of plankton and water quality was carried out from March to July 2016 at PunagaTakalar Experimental Pond at 6 ponds consisted of concrete ponds without 2 subplot of sand (pond A) and concrete pond with 2 subplate sand subplate (pond B) respectively measuring 1,000 m2 and a 2-square-meter plot of 2,500–3,000 m2 (pond C). The results showed that plankton abundance in pond A ranged from 37–349 individuals/L, pond B ranged from 35–1,399 individuals/L and pond C ranged from 54–999 individuals/L. The most common phytoplankton genera in this study was Oscillatoria while for zooplankton is of Acartia. The diversity of plankton in ponds A, B and C is included in the community of unstable to moderate biota. In general, the diversity of plankton in pond B is included in the community of moderate biota. The plankton uniformity index in pond A, pond B and pond C is generally close to 1 this indicates that the existence of plankton species in the three ponds is relatively even.

Ecological Drivers of Cladoceran Diversity in the Central European City (Łódź, Poland): Effects of Urbanisation and Size of the Waterbody

Łodź, one of the largest cities in Poland, is characterized by the presence of a large number of artificial and natural waterbodies. It, therefore, offers a great opportunity to study ways in which urbanisation affects cladoceran fauna associated with urban areas. We hypothesize that size of the waterbody is more important for the diversity and composition of cladocerans in urban ponds than direct effects of urbanisation. To test this assumption we analysed 21 ponds of different size and location along the urbanisation gradient. Redundancy analysis (RDA) based on 17 environmental factors and urbanisation parameters showed that distance from the city centre, number of plant species and pH were the most important factors shaping cladoceran fauna in urban ponds of Łodź. Non-metric multidimensional scaling (NMDS) based on the Bray-Curtis formula demonstrated that pond size (depth and surface area) was reversely related to the level of urbanisation, i.e., larger and deeper waterbodies were generally found in the outer city zone. The effect of urbanisation, resulting in a lower number of species and lower abundance in ponds located in the central part of the city, was indirect and resulted from the lower number of large ponds in this zone.

Influence of Weather, Wetland Availability, and Mallard Abundance on Productivity of Great Lakes Mallards (Anas platyrhynchos)

Waterfowl rely on breeding habitat availability for successful reproduction. Breeding habitat availability likely changes throughout the season and among years as weather patterns change and thus productivity rates are likely susceptible to these changes. We used data from 1961 to 2011 to investigate effects of weather, breeding habitat availability and abundance of breeding mallards (Anas platyrhynchos) on productivity rates of mallards breeding in the Great Lake states (Michigan, Minnesota, and Wisconsin; hereafter GLS). We hypothesized that productivity rates would increase with wetter and warmer conditions however, extreme temperatures may have a negative impact and that high breeding density may negatively impact productivity rates. Specifically, we looked at the effects of average June and July temperature and precipitation, the Palmer Hydrological Drought Index (hereafter PHDI), and wetland counts to model productivity rates across the three states for the time series. We used a reduced time series model set to evaluate the impacts of wetland counts on productivity. We found that in general, wetter conditions, as indexed by high positive PHDI values and relationships with pond abundance, positively affected productivity. We believe that breeding habitat availability is likely a reasonable predictor of mallard productivity rates in the GLS.

Quantifying geographic variation in the climatic drivers of midcontinent wetlands with a spatially varying coefficient model.

The wetlands in the Prairie Pothole Region and in the Great Plains are notorious for their sensitivity to weather variability. These wetlands have been the focus of considerable attention because of their ecological importance and because of the expected impact of climate change. Few models in the literature, however, take into account spatial variation in the importance of wetland drivers. This is surprising given the importance spatial heterogeneity in geomorphology and climatic conditions have in the region. In this paper, I use spatially-varying coefficients to assess the variation in ecological drivers in a number of ponds observed over a 50-year period (1961-2012). I included the number of ponds observed the year before on a log scale, the log of total precipitation, and mean maximum temperature during the four previous seasons as explanatory variables. I also included a temporal component to capture change in the number of ponds due to anthropogenic disturbance. Overall, fall and spring precipitation were most important in pond abundance in the west, whereas winter and summer precipitation were the most important drivers in the east. The ponds in the east of the survey area were also more dependent on pond abundance during the previous year than those in the west. Spring temperature during the previous season influenced pond abundance; while the temperature during the other seasons had a limited effect. The ponds in the southwestern part of the survey area have been increasing independently of climatic conditions, whereas the ponds in the northeast have been steadily declining. My results underline the importance of accounting the spatial heterogeneity in environmental drivers, when working at large spatial scales. In light of my results, I also argue that assessing the impacts of climate change on wetland abundance in the spring, without more accurate climatic forecasting, will be difficult.

Estimating Natural Mortality Rates of Juvenile White Shrimp Litopenaeus setiferus

Comparisons of natural mortality rates can be used to identify essential habitat and nursery areas for fishery species. We estimated and compared natural mortality rates of juvenile white shrimp Litopenaeus setiferus using length-frequency and mark-recapture data and attempted to identify factors that may affect these mortality rates. Daily instantaneous natural mortality rates (95 % confidence interval (CI)) obtained from length-frequency data by following individual cohorts were 0.043 (0.031–0.054) and 0.014 (0.0–0.039). Combining all length-frequency data, converting to age-frequency data, and using two types of catch-curve analyses yielded estimates of 0.069 (0.042–0.095) and 0.060 (0.046–0.073). Mark-recapture estimates obtained in a separate study from two ponds were 0.129 (0.054–0.203) and 0.014 (−0.048–0.076). These estimates are comparable to previously reported values for this species, but we are the first to report a measure of precision with our estimates. In the mark-recapture study, mortality rates appeared to be related to predator abundance in ponds and flooding patterns of the surrounding marsh. The only mortality rate significantly different from any of the other estimates was the lower of the two length-frequency estimates, but this result should be interpreted with caution because of the uncertainty in that estimate, relative imprecision of our estimates, and confounding factors between the methods we used to estimate mortality. Despite this caveat, the results from our study can be used to improve population models for L. setiferus and our understanding of the role of marsh habitats as nursery areas.

Impact of pond aquaculture effluents on seagrass performance in NE Hainan, tropical China

The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ15N in seagrass leaves and epiphytes (6–9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ34S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation.

Top‐down control of prey increases with drying disturbance in ponds: a consequence of non‐consumptive interactions?

1. Biotic interactions are often expected to decrease in intensity as abiotic conditions become more stressful to organisms. However, in many cases, food-web and habitat complexity also change with abiotic stress or disturbance, potentially altering patterns of species interactions across environmental gradients. 2. We used a combination of field assays and mesocosm experiments to investigate how disturbance from desiccation moderates top-down control of prey by predators across a gradient of pond duration in New Zealand. 3. Field manipulations of predator abundance in ponds led to an unexpected decrease in the top-down control of prey biomass by predatory invertebrates as pond duration increased (decreasing abiotic stress). Predatory fish, which are restricted to permanent ponds, had negligible effects on prey biomass. Mesocosm experiments further indicated the consumptive effects of fish are weak; a result that cannot be explained by an increase in physical habitat refugia in relatively more permanent ponds. 4. Manipulations of invertebrate predator diversity in mesocosms (both substitutive and additive treatments), and the addition of olfactory fish cues, revealed that strong non-consumptive effects of fish reduced predation by predatory invertebrates, and these effects overwhelmed the positive influence of invertebrate predator diversity on prey consumption. 5. These results suggest that decreases in top-down control with increasing pond permanence are likely a result of non-consumptive effects of fish weakening predation by invertebrate predators in the more complex food webs of permanent ponds. Therefore, considering non-consumptive effects of predators in complex food webs will likely improve the understanding of biotic interactions across environmental gradients.

Effects of pine invasion on anurans assemblage in southern Brazil coastal ponds

The destruction of wetlands due to afforestation areas is a common activity in temperate and subtropical regions in Southern America. The expansion of pine in the Coastal Plain of Southern Brazil is out of control and its impacts on aquatic biodiversity are little known. We tested the following hypotheses: the pine occurrence diminishes the anuran richness and abundance in ponds and it changes the anuran composition; the beta-diversity between pine and native grassland matrix ponds (natural ponds) is determined mainly by nestedness. Sampling was carried out from 2007 to 2009 in five ponds in pine invasion matrix and five ponds in native grassland matrix. The natural ponds showed a greater richness of tadpoles (10 species) than pine ponds (5 species). The mean richness of adults was higher in natural ponds than pine ponds throughout the entire study. The species composition was different between natural and pine ponds, for both adults and tadpoles. Comparing natural ponds with each other and the pine ponds with each other, our results showed that neither nestedness nor turnover was determinant for beta-diversity. However, when natural ponds were compared with pine ones, we found that the contribution of nestedness was higher for the anurans beta-diversity than turnover. Increases in the nestedness mechanism indicated that the pine occurrence results in species loss in Southern Brazil ponds. Since 90% of its wetland has been already affected, the removal ofPinusin the conservation areas in southern Brazil is important to minimize their impacts on aquatic biodiversity.