Effect of land use on pollution status and risk of fish endocrine disruption in small farmland ponds

To study whether the intensity of agricultural activities affects pesticides loads in pond environment, a large number of Belgian farmland ponds were surveyed in spring 2004. Temporal distribution of pollutants was also investigated over restricted survey ponds sampled three times round year 2007. Sedentary pond Prussian carp juveniles were also captured to determine their brain aromatase activity (AA) and plasma vitellogenin (VTG) levels. Heavy metal distribution was also examined in various pond matrices. Amongst the pesticides analysed, only herbicides were detected. Contamination of pond water by atrazine was frequently observed during spring 2004, while isoproturon and glyphosate were detected round year 2007. Levels of herbicides were inversely related to the distance of ponds to crop field, and values peaked in April or October. Absence of endocrine disruptors in pond water was confirmed by lack of modulation in VTG and AA in male fish. Heavy metals were present in all the pond matrices, but overall contamination levels were low. The results demonstrated that Belgian ponds were mainly contaminated by herbicides and that pond sedentary fish were not affected by endocrine disruptors. They also demonstrated a marked effect of land-use intensity on herbicide pollution which can be mitigated by an adjustment of the buffer zones.     

Hazing and movements of Canada geese near Elmendorf Air Force Base in Anchorage, Alaska

Bird strikes to aircraft are a serious economic and safety problem in the United States, annually causing millions of dollars in damage to civilian and military aircraft and the occasional loss of human life. We observed movements of 1236 neckbanded lesser Canada geese (Branta canadensis parvipes) to determine efficacy of hazing as a means to reduce goose presence at Elmendorf Air Force Base (EAFB), Anchorage, Alaska from August to October 1997. Emphasis was on movements of geese onto EAFB with additional data collected at the other two major airports in the area, Anchorage International Airport (AIA) and Merrill Field Airport (MFA). Daily observations indicated the presence of 208 individual neckbanded geese on EAFB, and 20% returned more than once after being hazed from EAFB. We identified three staging areas, geese utilized prior to entering EAFB, and three post-hazing dispersal sites. Collared geese began moving onto EAFB 30–40 days post-molt with the largest proportions moving onto EAFB 70–90 days post-molt. We observed 75 neckbanded geese on AIA from seven molting sites, and 23% returned more than once after being hazed from AIA. We observed 141 neckbanded geese on MFA from 14 molting sites, and 21% returned more than once after being hazed from MFA. Our data indicated that as long as local goose populations increase, large numbers of Anchorage area geese are likely to enter one of the airports creating a variety of management problems. Hazed geese returning to airports multiple times present a special hazard to aircraft safety because they appear to have become habituated to non-lethal scare tactics. We recommend an integrated management approach to limit the Anchorage area goose population utilizing various control techniques which are acceptable to Anchorage residents while continuing the hazing program at area airports.     

Effects of hydroperiod and predation on a Mississippi River floodplain invertebrate community

 The objective of this study was to determine if pond permanence and vertebrate predation (by fish and waterfowl) affect invertebrate community structure in the mudflat habitat of floodplain ponds. Invertebrate communities were studied for 1 year in four Mississippi River floodplain ponds with different hydroperiods. Pond 1 experienced five dry periods, pond 2 experienced four, pond 3 dried once, and standing water remained in pond 4 for the entire year. Vertebrate predator exclusion treatments (all access, no access, small-fish access and cage controls) were placed in all ponds. As pond duration increased, predatory invertebrate richness and abundance increased while overall invertebrate richness and abundance decreased. With the exception of the cladoceran Diaphanosoma, all commonly encountered taxa were strongly affected by pond permanence in terms of abundance, biomass and, generally, individual biomass. Taxa were nearly early divided between those that were more abundant in less permanent ponds and those that were more abundant in longer-duration ponds. Invertebrate taxa richness, abundance, and total biomass were lower in the all-access treatment than in the treatments that restricted predator access, and these effects were stronger in the more permanent ponds. In general, there were no significant differences in responses to the treatments with small-fish access and no access. These results support models that predict relatively weak effects of predation in frequently disturbed habitats. Received: 30 May 1995 / Accepted: 21 June 1996     

Spatiotemporal allozyme variation in the damselfly, <Emphasis Type="BoldItalic">Lestes viridis</Emphasis> (Odonata: Zygoptera): gene flow among permanent and temporary ponds

Several insect species seem to persist not only in permanent but also in temporary ponds where they face particularly harsh conditions and frequent extinctions. Under such conditions, gene flow may prevent local adaptation to temporary ponds and may promote phenotypic plasticity, or maintain apparent population persistence. The few empirical studies on insects suggest the latter mechanism, but no studies so far quantified gene flow including both pond types. We investigated the effects of pond type and temporal variation on population genetic differentiation and gene flow in the damselfly Lestes viridis in northern Belgium. We report a survey of two allozyme loci (Gpi, Pgm) with polyacrylamide gel electrophoresis in 14 populations from permanent and temporary ponds, and compared these results with similar data from the same permanent populations one year before. The data suggested that neither pond-drying regime, nor temporal variation have a substantial effect on population genetic structuring and did not provide evidence for stable population differentiation in L. viridis in northern Belgium. Gene flow estimates were high within permanent and temporary ponds, and between pond types. Our data are consistent with a source-sink metapopulation system where temporary ponds act as sinks in dry years, and are quickly recolonized after local population extinction. This may create a pattern of apparent population persistence of this species in permanent and temporary ponds without clear local adaptation.     

Does the morphology of beaver ponds alter downstream ecosystems?

Differences among lake morphologies often explain variation in characteristics of lentic ecosystems. Although beaver ponds also vary in morphology, previous studies have not examined the effects of such variation on downstream ecosystems. This study evaluated downstream effects of multiple beaver ponds in the Colorado Rocky Mountains during one low and one high-flow year. Beaver pond morphology was described as the natural log transformed ratio of beaver dam height (which determines hydraulic head) to pond surface area and related to pond spillover phytoplankton and characteristics of the ecosystem downstream (nutrient concentrations, limiting nutrients, periphyton, benthic organic matter (BOM), and benthic invertebrate consumers). Nitrate concentration increased systematically downstream of beaver ponds, but only in the low flow year when groundwater influences predominated. Effects of beaver ponds on soluble reactive phosphorus concentration depended on pond morphology, increasing downstream of small ponds with high dams, but only during the low-flow year. In situ experiments showed that neither beaver activity nor pond morphology predicted periphyton-limiting nutrients downstream. Both periphyton biomass and BOM decreased downstream of small ponds with high dams but pond morphology did not predict abundance of invertebrate grazers or detritus-feeding consumers. While suspension feeding invertebrates increased downstream from small ponds with high dams, variation in chlorophyll a from water spilling over beaver dams did not follow a similar pattern. We conclude that the effects of beaver ponds on downstream nutrients, resources and consumers are rarely systematic, but instead depend on variation in pond morphology and on annual hydrologic variation.     

Spatiotemporal allozyme variation in the damselfly, Lestes viridis (Odonata: Zygoptera): gene flow among permanent and temporary ponds

Several insect species seem to persist not only in permanent but also in temporary ponds where they face particularly harsh conditions and frequent extinctions. Under such conditions, gene flow may prevent local adaptation to temporary ponds and may promote phenotypic plasticity, or maintain apparent population persistence. The few empirical studies on insects suggest the latter mechanism, but no studies so far quantified gene flow including both pond types. We investigated the effects of pond type and temporal variation on population genetic differentiation and gene flow in the damselfly Lestes viridis in northern Belgium. We report a survey of two allozyme loci (Gpi, Pgm) with polyacrylamide gel electrophoresis in 14 populations from permanent and temporary ponds, and compared these results with similar data from the same permanent populations one year before. The data suggested that neither pond-drying regime, nor temporal variation have a substantial effect on population genetic structuring and did not provide evidence for stable population differentiation in L. viridis in northern Belgium. Gene flow estimates were high within permanent and temporary ponds, and between pond types. Our data are consistent with a source-sink metapopulation system where temporary ponds act as sinks in dry years, and are quickly recolonized after local population extinction. This may create a pattern of apparent population persistence of this species in permanent and temporary ponds without clear local adaptation.     

Promoting dragonfly diversity in cities: major determinants and implications for urban pond design

Urbanisation is increasing and it is essential to integrate biodiversity into the spatial planning of urban areas. This requires deeper understanding of biodiversity patterns in cities. We investigated which habitat variables are major determinants of dragonfly diversity and species assemblage structure in the municipal area of Dortmund (Germany). We sampled dragonfly larvae in 33 ponds situated in city parks, commercial, residential and agricultural areas. We recorded 30 autochthonous dragonfly species with species richness ranging from zero to 17. Additionally, we surveyed a set of environmental variables including habitat size, water level, pond structures and vegetation as well as surrounding landscape and potential disturbances like waterfowl and fish. Multivariate methods were used to identify the major determinants of dragonfly diversity, abundance and assemblage structure. Analysis indicated that diversity of aquatic and terrestrial vegetation affected dragonfly diversity positively. City park ponds had low diversity, but Ischnura elegans was obviously promoted by the specific park pond conditions, including high waterfowl density. We found five assemblages mostly determined by generalistic species which were related to different pond types. Moderately disturbed ruderal and pioneer ponds in residential and agricultural areas also contained increased numbers of rare species. Our results indicate that urban ponds may have a great value for maintaining biodiversity, but various disturbances have negative impact. To promote urban biodiversity we suggest a natural design of well-vegetated ponds as well as a high diversity of different pond types and particularly a more-natural redesign of city park ponds.     

Flexible antipredator behavior in a dragonfly species that coexists with different predator types

Two of the main predators of dragonfly larvae, insectivorous fish in communities with fish and large dragonfly species in communities without fish, differ markedly in their mode of predation. In general, dragonfly species coexist successfully with one predator or the other, but larvae of the dragonfly Pachydiplax longipennis can coexist successfully with both. I examined the behavioral response of these larvae to a simulated predator attack to determine whether their response (1) differs between the two communities, and (2) is sensitive to waterborne cues about the type of predator present. I compared larvae from two different communities: fish ponds where insectivorous fish were the top predators, and fish-free ponds where large dragonflies were the top predators. Larvae from fish-free ponds actively moved away from an attack significantly more than did larvae from fish ponds, provided each was attacked in its native pond water. Larvae collected from a fish-free pond but then attacked in fish water moved less than did controls (larvae attacked in fish-free water). Likewise, larvae collected from a fish pond but attacked in fish-free water moved more than did controls (larvae attacked in fish water). Larvae attacked first in water from their native pond and then in water from the contrasting pond changed their response in the expected direction. These results indicate that escape behavior in P. longipennis differs between communities with different predator types and is sensitive to waterborne cues in a manner consistent with the mode of predation employed by each predator.     

南美白对虾淡化养殖对周边环境盐碱化的影响分析

为探讨淡化养殖南美白对虾(Penaeus vannamei)对养殖区周边环境盐碱化的影响,本研究对湖南澧县南美白对虾淡化养殖1年、3年、5年和7年的池塘及排水沟渠附近底泥样品进行了钾、钙、镁、钠、水溶性盐总量、氯离子等土壤盐碱化指标分析.结果显示,养殖池塘水溶性总盐含量均高于对照组.对比对照组,养殖池塘沉积物的氯离子浓...     

Adaptive divergence vs. environmental plasticity: tracing local genetic adaptation of metamorphosis traits in salamanders

In order to assess the significance of local adaptation relative to environmental plasticity on the evolution of life history traits, we analysed the possible genetic basis of differences between pond- and stream-breeding fire salamanders (Salamandra salamandra) in Germany. These salamanders typically deposit their larvae in small streams, where they grow until they are sufficiently large to metamorphose. However, some populations in Western Germany use ponds as larval habitat. Because habitat quality of streams differs from that of ponds one expects life history differences in the pond animals, which may result either from a plastic response or through genetic differentiation (i.e. local adaptation). Using a phylogeographical analysis of mitochondrial D-loop sequences, we show that both stream and pond populations in Western Germany are derived from a single lineage that recolonized following the last glaciation. This finding suggests that pond breeding originated very recently. Our studies of habitat quality and metamorphic behaviour of larvae in natural ponds and streams disclosed that pond larvae experience a significantly reduced food supply and greater risk of drying than do stream larvae. Pond larvae metamorphose earlier at the cost of reduced mass. Common-environment experiments with pond and stream larvae show that metamorphic behaviour of pond larvae under limited-food conditions is determined genetically and is not simply a plastic response to the differing habitat conditions. These results show that phenotypic plasticity is less important than local adaptation in explaining differences in ecological diversification within this species and suggests the possibility of rapid evolution of genetic adaptations when new habitats are exploited.     

Productivité comparée des deux étangs situés à proximité du lac Saint-Jean,au Québec

The Comparative Productivity of Two Ponds in the Vicinity of Lake St-John, Québec In 1980 and 1981, the productivity of two ponds near Lake St. John were evaluated. One, the pond of Desbiens, did not communicate with Lake St. John and the other, the pond of St-Gédéon, was connected to the lake. The aim of this study was to evaluate the contribution that a pond could make to the increase in productivity of Lake St. John which is a reservoir. The pond of Desbiens is more productive than Lake St. John but two to three times less than the pond of St-Gédéon. The pond of Desbiens shows an advanced degree of eutrophication whereas the pond of St-Gédéon is similar to the northern lakes by its physico-chemistry, zooplankton, sediments and benthic fauna. If we want to create artificial ponds, for a better productivity of reservoirs, it is important that they be connected to each other.     

Patterns in benthic food webs: a role for omnivorous crayfish?

1. The biomass and species richness of macrophytes and invertebrates in artificial ponds at two sites in southern Sweden (twenty-one ponds at each site) were investigated. Alkalinity was high at one site (H ponds) and low at the other site (L ponds). The ponds chosen had different densities of signal crayfish (Pacifastacus leniusculus), with mean crayfish abundance (estimated by trapping and expressed as catch per unit effort) significantly higher in the L ponds (10.7) than in the H ponds (4.9). Macrophytes, invertebrates, the amount of periphyton on stones and the organic content of the sediment were determined in each pond. 2. Macrophyte biomass, cover and species richness declined with increasing crayfish density. Macrophyte species composition differed between ponds and was related to crayfish abundance. 3. The total biomass of invertebrates and the biomass of herbivorous/detritivorous invertebrates declined with increasing crayfish abundance, but the biomass of predatory invertebrates declined only in the L ponds. The relative biomass of Gastropoda and Odonata declined in ponds where crayfish were abundant. In ponds where crayfish were abundant the invertebrate fauna was dominated by sediment-dwelling taxa (Sialis (H and L ponds) and Chironomidae (H ponds)). 4. The number of invertebrate taxa in macrophytes declined with increasing crayfish abundance. The percentage of macrophyte-associated invertebrate taxa differed between ponds, but also between sites. The relative biomass of Gastropoda declined in H ponds where crayfish were abundant. In H ponds Trichoptera or Gammarus sp. and Heteroptera dominated where crayfish were abundant, whereas Odonata dominated in L ponds with abundant crayfish. 5. The organic content of the sediment decreased in ponds with high crayfish densities, while the amount of periphyton on stones was not related to crayfish density. 6. We conclude that the signal crayfish may play an important role as a keystone consumer in pond ecosystems, but lower trophic levels did not respond to changes in the abundance of the crayfish according to the trophic cascade model. Omnivorous crayfish may decouple the cascading effect.     

Landscape epidemiology of Batrachochytrium dendrobatidis in central California

Amphibian chytridiomycosis (caused by Batrachochytrium dendrobatis; Bd) was first identified in 1998 and has since been implicated in numerous amphibian declines worldwide. Most researchers have since investigated broad‐scale geographic and taxonomic occurrences of the pathogen in tropical lotic or cool montane systems. In this study, we analyzed how environmental factors, land use practices, and landscape structure may affect the dynamics of the pathogen's distribution in a landscape dominated by lentic systems within a region of Mediterranean climate. We quantified the occurrence of Bd testing the six resident amphibian species that occur in 54 isolated perennial and ephemeral ponds in central California between May and June annually from 2004 to 2007. The geographic distribution of Bd within the landscape varied markedly between years. Inter‐annual variation in climate affected the pond landscape structure indicating that climate conditions indirectly influence the distribution of the pathogen. Fourteen ponds, 12 perennial and 2 ephemeral, were positive for Bd≥3 yr of the study and were treated as Bd hotpots for comparative purposes. Occurrences of Bd within the landscape were spatially autocorrelated and ponds within ~1000–1500 m of Bd hotspots were more likely to test positive. Local land use, (presence/absence of grazing or recreational activity and developed lands), did not influence Bd status of a pond, indicating that the most likely means of Bd transmission between ponds may be waterfowl and/or amphibians.     

Breeding pond fidelity in the common toad, Bufo bufo

Two independent studies of adult common toad, Bufo bufo , movements between different spawning ponds/populations both within and between years were made in England and Sweden during the spring breeding periods of1987–1990. The results of the two studies were subsequently combined since they were found to be complementary. In addition, in England during 1984 and 1985, large numbers of 'toadlets' were marked so that they could be identified if recaptured as breeding adults.
The degree of relocation between ponds was negatively correlated to the distance between ponds. The proportion of both males and females that moved between ponds within a particular year was significantly less than the proportion relocating between years. In any year, between 79% and 96% of adults that survived to breed the following year, returned to the original pond. Similarly, of the toadlets marked during1984–85, 81% of the males that subsequently returned as breeding adults were captured in their pond of origin.
Isolation, in relation to both population dynamics and population genetics, is defined and its implications for the management of common toad populatins discussed.     

Habitat Use by Waterbirds in Relation to Pond Size,Water Depth,and Isolation: Lessons from a Restoration in Southern Spain

Wetland restoration is increasingly important to reverse habitat degradation, recover ecosystem services, and maintain biodiversity. To aid project design, more information is required on the influence of wetland size, depth of water, and isolation on the waterbird communities that become established. During a restoration project in Doñana, one of the Europe's most important wetland complexes, an experimental network of 96 temporary ponds with standard shape but variable size, water depth, and isolation was created. We surveyed the waterbird community in spring from 2006 to 2008 and related species abundance and richness to abiotic pond characteristics. We also performed analyses pooling species by foraging guilds or body size. Waterbird abundance and species richness were highest in 2007, the wettest year when the ponds had longer hydroperiods. Larger ponds had consistently higher abundance and species richness for the entire community and for different guilds and body sizes. Moreover, the density of birds per hectare was higher in large ponds than in the smaller ones. Pond isolation and excavated depth did not affect overall abundance and richness, although opposing effects of depth were observed on some size classes, and ducks and large birds preferred isolated ponds. Some bird groups preferred ponds at a particular location. This is the first waterbird study to address the importance of pond size, depth, and isolation independently of confounding variables such as pond shape. It illustrates the varied responses from different bird groups and demonstrates the importance of varying depth, location, and isolation to enhance community abundance and diversity .     

Transition from Planktonic to Benthic Algal Dominance Along a Salinity Gradient

Highly regulated salinity gradients in solar salt pond concentrating sequences provide an opportunity to investigate in situ salinity impacts on aquatic flora and fauna. The Shark Bay Salt solar ponds at Useless Inlet in Western Australia vary in salinity from seawater to four times seawater over the pond sequence. We observed a shift from planktonic to benthic primary productivity as salinity increased. Water column photosynthesis and biomass decreased markedly with increasing salinity, while benthic productivity increased as cyanobacterial mats developed. Correspondingly, productivity shifted from autotrophy to heterotrophy in the water column and from heterotrophy to autotrophy in the benthos. Both shifts occurred at intermediate salinity (S = 110 g kg⁻¹, ρ = 1.087 g cm⁻³) in the pond sequence, where there was little production by either. Within individual ponds, productivity, algal biomass and physico-chemical conditions were relatively constant over one year, with only water column photosynthesis significantly different between seasons, mostly due to greater winter production. Transitions between benthic and planktonic production and their relative magnitudes appear to be driven mostly by direct responses to salinity stress, but also by changes in nutrient availability and grazing, which are also influenced by salinity.     

Predation and the distribution and abundance of a pulmonate pond snail

Summary The abundances of a freshwater pulmonate snail, Lymnaea elodes were studied in a temporary pond and a permanent, more productive pond in northeastern Indiana, USA. When snails from both populations were reared in each of the ponds in containers excluding predators, snails grew to be 1.3 to 2 times as large in the more productive pond, and laid 9 times as many eggs. However, field sampling data showed adults to be more abundant in the temporary pond. The only obvious difference between the two ponds was the presence of the molluscivorous central mudminnow (Umbra limi) in the permanent pond. These fish fed upon L. elodes when eggs and juvenile snails were abundant. In an experiment in the temporary pond, addition of mudminnows lowered egg and juvenile snail survival in pens where snail abundances had been increased. We suggest that vertebrate predators like the mudminnow can be significant sources of mortality for thin shelled species like L. elodes, possibly excluding them from habitats like lakes and rivers.Address for offprint requests     

As integrated culture system for outdoor production of microalgae and cyanobacteria

Cultivation of microalgae in closed photobioreactors suffers from high temperatures, whereas in open raceway ponds the optimal temperature is seldom reached. With an integrated device coupling a raceway pond with a suitably sized and positioned closed system (alveolar panel), the heat accumulated in the panel was efficiently transferred to the pond and a near-optimum temperature regimen for Arthrospira platensis was maintained, with no need for any additional cooling device. The productivity obtained in the integrated system was higher than the sum of the productivities (g reactor⁻¹ day⁻¹) of the pond and panel systems operating separately. This revised version was published online in September 2006 with corrections to the Cover Date.     

Effects of hydrology on zooplankton communities in high-mountain ponds, Mount Rainier National Park, USA

Ten high-mountain ponds in Mount Rainier National Park, WashingtonState, were studied from ice-out in June through September1992to investigate the influences of fluctuating pond volumes onzooplankton communities. All of the ponds were at maximum volumeimmediately after ice-out. The temporary pond with the shortestwet phase was inhabited by rotifer taxa with short generationtimes and a crustacean taxon with the ability to encyst as drought-resistantresting bodies at immature stages of development. Dominant zooplanktontaxa in three other temporary ponds and six permanent pondswere similar. Rotifer densities typically were lower in temporaryponds relative to those in permanent ponds, although Brachionusurceolaris was abundant shortly before the temporary ponds dried.Large volume loss was associated with large declines in totalabundances of crustacean populations. Daphnia rosea was notpresent in temporary ponds following fall recharge. In deep-permanentponds, copepods had slower developmental rates, smaller temporalchanges in total abundances of crustacean populations and twoadditional large-bodied crustacean taxa were present relativeto the characteristics of crustacean communities in shallow-permanentponds. Owing to their small sizes and sensitivity to environmentalchange, collectively ponds such as these may provide an earlysignal of long-term climate change in aquatic systems.     

Life stage specific variation in the occupancy of ponds by Litoria aurea,a threatened amphibian

Breeding aggregations are a reproductive strategy to increase mate finding opportunity. However, because aggregations skew the distribution of mature animals through conspecific attraction, rather than resource availability, the distribution of breeding sites may be reduced, so that not all suitable breeding sites are used. To examine the relationship between landscape and reproductive strategies of a threatened frog, Litoria aurea, we studied its distribution at Sydney Olympic Park over two breeding seasons. We aimed to: (i) determine the distribution and predictors of breeding ponds; and (ii) assess the significance of dispersal in the juvenile age‐class. We found that the distribution of the calling males was highly skewed and occurred in large, well‐connected ponds. Despite this, breeding ponds were not aggregated; pond size was the single factor explaining the distribution of breeding ponds. Juvenile frogs dispersed from breeding ponds and were not associated with a specific pond characteristic. Less breeding occurred in the second season during which fewer ponds were used for breeding including many different ponds from the previous year. These changes suggest that breeding effort and breeding pond choice are dynamic and therefore knowledge of the factors that drive breeding events will be a powerful tool in managing species, particularly in light of changing climatic regimes.