Pond Types Research Articles

Productivity, Protein Content and Nutrient Removal from Anaerobic Effluents of Coffee Wastewater in Salvinia minima Ponds, under Subtropical Conditions

AbstractSalvinia minima is an aquatic fern which presents several advantages for the phytoremediation of wastewater. However, there is no information available for the operation of Salvinia‐based systems (SBS) for nutrient removal from organic matter enriched wastewater. The objective of this work was to establish the optimum range of some key parameters for the operation of Salvinia minima ponds treating anaerobic effluents of coffee wastewater (AECWW). Batch cultures were performed outdoors, under subtropical conditions (Xalapa, Veracruz, Mexico). At the first stage, various pH levels were tested. After choosing the optimum pH, two pond depths were evaluated (0.10 m and 0.27 m). It was found that the productivity in AECWW was strongly affected by the pH, as it decreased with the increase in the pH. In fact, growth was completely inhibited at pH 8.0. In contrast, productivity at a pH of 6.0 and a pond depth of 0.27 m during the summer was equivalent to 27.92 ton/ha × year. The percentage of TKN removal increased with the pH value: 51 ± 2.28% at pH 5.0; 78 ± 1.47% at pH 6.0 and. 97 ± 0.80% at pH 8.0. A similar situation was found for the case of NH4‐N removal: (55 ± 0.44%, 80 ± 1.1%, 99 ± 0.02%). The depth of the culture had influence on the productivity, protein content and nutrient removal. It was concluded that Salvinia minima is an adequate choice for the treatment and recovery of nutrients from AECWW. The pH for optimal operation of this type of pond was 6.0. The depth of the water column should be adjusted to 0.10 m for attaining a maximum relative removal efficiency (in terms of g NH4‐nitrogen/l × d), although the productivity would not be at its maximum under these conditions. On the contrary, depth should be adjusted to 0.27 m for reaching the maximum absolute removal efficiency (considering the total volume of the reactor) and the maximum productivity. During the late autumn and winter period, the AECWW should be diluted 1:2 in order to enhance ammonia nitrogen removal.

Which factors determine the abundance and distribution of picocyanobacteria in inland waters? A comparison among different types of lakes and ponds

In a limnological survey including 45 lakes and ponds from central-eastern Spain, we studied the main factors associated with the abundance of autotrophic pico-plankton (APP), mostly formed by unicellular picocyanobacteria (APP-Pcy). The study covers a wide range of trophic conditions, salinity, water flow regimes and lake typologies. Phycoerythrin (PE)-rich picocyanobacteria (PE-APP) were abundant in the metalimnion and upper hypolimnion of deep stratified lakes, exhibiting low nutrient availability in the epilimnion. Among these lakes, higher PE-APP abundances were found in lakes with higher retention time during periods of stability, whereas lakes with low retention time lacked conspicuous Pcy populations. They usually formed deep chlorophyll maxima in the nutrient-richer metalimnetic layers, especially when epilimnetic nutrient exhaustion occurred during stratification. The ratios of PE with respect to other photosynthetic pigments in deep lakes usually increased with depth. In these lakes, the available light is selectively enriched in the yellow-green range as depth increases, and these wavelengths can be selectively harvested by PE. Phycocyanin (PC)-rich APP without PE, mostly unicellular rod-shaped cyanobacteria, were only abundant in some hypertrophic shallow lakes, although in many lakes with highly eutrophic conditions their presence was very low or undetectable.

AREIAS E LAGOAS DO PANTANAL, BRASIL: HERANÇA PALEOCLIMÁTICA?

The Pantanal basin, in the central-western South America, presents many surprising features such as the giant Taquari alluvial fan; the great number of ponds, many of them with alkaline brine waters, mainly in the southwest part of the Taquari fan; the countless fossil geomorphic features preserved in the surface of the fan. A mantle of white sands is associated with these features extending to the adjacent source areas. The main doubts that these characteristics pose may be summarized in one question: would the Taquari and other fans be a sedimentary construction of the current semi-humid climate, or would it represent one geohistoric moment of a semi-arid climate? In this case, the unstability of these constructions may be meaningful and relevant to environmental occupation and management. Several researchers have already investigated some aspects, such as geomorphic characteristic in radar images, grain size distributions properties, current sediment dynamics etc., lasting without answer the central subject on the recent past dynamics. The characterization of the geomorphic features in aerial panchromatic photographs, Landsat images, with field support, comparatively to radar images, allowed a progress in its characterization. The sediment properties associated with these geomorphic features as well as to correlative deposits in the source area, brought a new understanding of its paleoenvironmental meaning. Dating of coal fragments and shells by C14 method helped historical development. The white sands, generalized at the Pantanal, is typical of the last pre-current event of sedimentation; frequently show granulometric characteristic of eolic deposition although the analysis of geoforms does not allow the recognition of dunes. An important characteristic is the textural inversion, evidencing the mixture of population with different inherited attributes from the source area. However, the mixture of population does not explain the characteristics of distribution such as very selective grain size. For its time, the several types of ponds, incorporate an older group of selected features: deflation hollows, later flooded, forming salted pans, surrounded by eolian constructions (lunetes, spurs) and small terraced ridges (“cordilheiras”). These constructions are made up of white fine sands, with good sorting, that represent a testimony of eolian action. The remobilization of these sands previously worked, had been done by hidrologic flows in braided channels or in sheet floods, where the sediments were dispersed by crevasses and avulsion lobes, interfingering in the previous landscape, destroying it partially and building the lobes of the Taquari fan. The mantle of eolian white sands, that covers red paleolatosoils, either in the Taquari fan or in the adjacent areas, is interpreted as the record of an arid and cold paleoclimate, contemporary to the last glacial event in terminal Pleistocene. The eolian forms are relicts and they are largely obliterated by the restoration of alluvial fan systems. Because of high sedimentary charge due to the change in the pluviometric regime, the construction of depositional lobes was dominated by alluvial processes (braided channels, crevasses, avulsion lobes and sheet flows). This event, attributed to the climatic changes in the beginning of Holocene, has caused elevation of the regional phreatic level and formation of ponds in the remaining depressions of eolian deflation due to its isolation their waters became progressively brine. Great part of this landscape is progressively being destroyed by the current processes of tributary drainage (“vazantes “), established on the old lobes with partial reutilization of the previous distributary channel valleys.

BREEDING DUCKS AND THEIR HABITATS IN THE HIGH PLAINS OF TEXAS

Abstract The High Plains of Texas is one of the southernmost nontraditional breeding areas for many duck species in North America. Because of a paucity of information on breeding ducks there, we conducted roadside surveys of breeding ducks and their habitats during May and June from 1988 through 1992. Breeding pairs of 15 species were observed on 6 types of ponds (natural and man-made wetlands containing surface water). Mallard (Anas platyrhynchos) density ranged from 9.1 to 23.1 pairs/100 km2, and density for all species combined ranged from 14.8 to 46.7 pairs/100 km2 (all years and survey periods included). Occupancy rates were highest on playa lakes and impoundments, though all pond types had occupancy rates exceeding 26% (all surveys and years). Duck pairs per occupied pond were highest on playa lakes (>7 and >4 on May and June surveys, respectively), followed by impoundments (>5 and >2) and entrenched draws (>2 and >3). Although the density of breeding pairs in the High Plains of Texas (47 pairs/100 ...

Responses of amphibians to restoration of a southern Appalachian wetland: Perturbations confound post-restoration assessment

Although regulatory, agencies in the USA typically require 3–5 yr of post-restoration monitoring of biotic responses to wetland mitigation, many researchers have argued that longer time frames are needed to assess population responses adequately. We conducted an 8-yr study to examine the demographic responses of the wood frog (Rana sylvatica) and spotted salamander (Ambystoma maculatum) to wetland creation at a mitigation bank in western North Carolina. Our primary goals were to compare juvenile output in ten reference and ten constructed ponds and to assess the overall change in breeding population size in response to site restoration. We used annual censuses of egg masses to assess changes in breeding population size and used estimates of larval population size at hatching and the initiation of metamorphosis to assess embryonic and larval survival. Adults of both species bred in most constructed ponds within a few months after filling in 1996. Estimated juvenile production from 1996 to 2002 did not differ significantly between pond types for either species. The percentage of both constructed and reference ponds that produced juveniles decreased markedly from 1996 to 1998 and remained low through 2002. The decrease in juvenile output was mostly associated with reduced larval survival rather than increased embryonic mortality across years. Drought and outbreaks of a pathogen (Ranavirus) were the primary causes of low juvenile production from 1998 to 2002. The overall breeding population of R. sylvatica increased markedly in 1999–2000 following a large recruitment of juveniles from constructed ponds in 1996–1997. With the onset of drought and ranaviral infections, the population declined to levels in 2002 that were at or below 1995 pre-restoration numbers. Despite site perturbations, the breeding population of A. maculatum remained relatively stable from 1995 to 2002, a phenomenon that may reflect selection for delayed reproduction and iteroparity in this species. Although we have monitored R. sylvatica and A. maculatum for seven breeding seasons after the creation of seasonal wetlands, we are still uncertain that site restoration will achieve the goal of increasing breeding populations above pre-restoration levels. Because amphibians have significant population lags and are sensitive to site perturbations, monitoring that exceeds five years may be required to assess demographic responses to site restoration adequately.

Nutrients, phytoplankton and harmful algal blooms in shrimp ponds: a review with special reference to the situation in the Gulf of California

The present work is a first attempt to document the latest reports on the occurrence of algal blooms in shrimp farm ponds worldwide. Particular emphasis is placed on discussing the relation of algal blooms with nutrients, with special reference to the northwest of Mexico. Typically, shrimp pond waters are enriched with organic matter and nutrients whose concentrations depend mostly on the management (i.e. higher stocking densities, water use, food and fertilizers). Generally, more intensive culture systems produce higher loads of nutrients in their discharge (e.g. N and P). Nitrogen and P concentrations vary in pond waters; N/P ratio ranges from 1.1 to 67 with values being more frequently between 1.1 and 6.8. Such variations are closely related with the cycling and supply of nutrients in the ponds. In shrimp farms located in NW Mexico, phytoplankton abundance varies widely, having a higher abundance in advanced stages of the culture cycle. In the most common pond types (intensive and semi-intensive), Synechocystis diplococcus (cyanobacteria) was the dominant species (>88.9%), followed by Peridinium trochoideum ( Scrippsiella trochoidea) and eventually Prorocentrum minimum and Gymnodinium spp. (dinoflagellates). The numerous occurrences of large blooms of dinoflagellates and other functional groups such as cyanobacteria, diatoms, chlorophytes and flagellates mean economic losses for farm industry on account of shrimp mortality or growth diminution due to poisoning, anoxic or mucus production effects, in which shrimp were mortality provoked in different regions: in China, the dinoflagellates Alexandrium tamarense ( Gonyaulax tamarensis) and Gymnodinium; in Malaysia, the raphidophyte Hornellia ( Chattonella) and the dinoflagellate Pyrodinium bahamense var. compressum; in Vietnam, the diatom Nitzchia navis- varingica; in Ecuador, the dinoflagellate Gyrodinium instriatum; and in NW Mexico the cyanobacteria S. diplococcus, Schizothrix calcicola, and the dinoflagellates P. minimum, and lastly Gymnodinium catenatum from supply waters.

Sludge accumulation pattern in an anaerobic pond under Mediterranean climatic conditions

The main objective of this study was to observe the sludge accumulation pattern of an experimental, covered, anaerobic pond treating municipal wastewater under Mediterranean climatic conditions throughout a 2-year operational period (1999–2000) in order to form a seasonal sludge accumulation model which may be used to predict the required desludging time, not only of the particular anaerobic pond used in the study, but also for other types of anaerobic ponds and operational situations. The 4-m deep pond was supplied with pre-screened, untreated wastewater from the nearby treatment plant of Thessaloniki, Greece, initially at a flow rate of 120 m 3/day and later at a flow rate of 150 m 3/day. The influent characteristics were BOD 5 441 mg O 2/L, COD 942 mg O 2/L and suspended solids (SS) 574 mg/L. BOD 5, COD, and SS concentrations of the pond effluent were reduced by 50%, 53%, and 64%, respectively, in comparison with those of the influent. During the operational period, three distinctly different zones were seen to form within the anaerobic pond: The first zone, which formed at the bottom of the pond, consisted of inert, high-density sludge. The second zone, which formed above this, contained a high concentration of volatile (easily biodegradable) sludge. The third upper zone (supernatant), was a liquid layer low in suspended solids. The accumulation of sludge in the pond followed an annual sinusoidal pattern with high values during winter and low ones during summer due to the increased digestion rate. The maximum high-density sludge height observed was 0.7 m, or 2% (14 m 3) of the total pond volume. The maximum volatile sludge accumulation reached 3.1 m, or 53% (300 m 3) of the pond volume. A seasonal sludge accumulation model, based on the sludge inflow and seasonal digestion rates, was used to simulate the annual fluctuation in accumulation rate for the local (Mediterranean type) climatic conditions. Monthly values of accumulation (or digestion) rate of sludge ( K AS) were experimentally estimated at specific mean monthly air temperatures and approximated by a regression second degree polynomial equation to be used with the model. The predicted desludging interval for our experimental pond was 3 years.

A comparative study of phenotypic traits related to resource utilization in anuran communities

Larval anuran communities vary along a gradient of pond permanency. The families Hylidae, Ranidae, and Bufonidae have each diversified into multiple pond types. Species using ponds that dry seasonally (vernal ponds) must compete well to metamorphose before pond drying, while permanent ponds, which contain more predators, produce weaker selection for competitive ability. Quantifying phenotypic traits related to resource acquisition in 14 anuran species provides insight into the mechanistic underpinnings of adaptive radiation in anuran lineages. Under controlled laboratory conditions and at both early and late developmental stages, relative growth rate, relative consumption rate, assimilation efficiency and production efficiency varied significantly among species. As predicted, vernal pond species had high growth rates relative to species using more than one pond type. However, within a pond type, families frequently differed in phenotype. In species using permanent ponds with fish predators, hylids had high growth rates while ranids had low growth rates, and in species using vernal ponds, bufonids had higher assimilation efficiencies than hylids. Differences also occurred between stages; hylids and ranids in permanent, but fishless, ponds were similar at an early stage, but late stage hylids in the same pond type had lower growth and consumption rates, and higher assimilation efficiencies than ranids. Functional relationships between phenotypic traits also differed among species and developmental stage. Negative correlations between evolutionary change (independent contrast values) in both mass and growth rate (both stages), and mass and consumption rate (late stage), suggest the presence of trade-offs. These results indicate that different lineages have diversified in different ways into the same pond types.

Sensitivity Analysis of Stabilization Pond System Design Parameters

Two stabilization pond systems are examined. A sensitivity analysis is undertaken, aimed at investigating the influence of the pond depths on stabilization pond surface area and pond volume for the specific combination of temperature, wastewater characteristics and effluent requirements. The dependencies are presented in a functional form, allowing for the graphical solution of the unit pond volume, area, and hydraulic residence time as a function of the respective pond depths. Based on these graphs, designers can determine the most appropriate depth value for each type of pond that minimizes the required area or volume, or balances excavation versus land acquisition and floor lining costs, taking under consideration the topographic and other local characteristics of the site area.

Local Population Differences in Phenotypic Plasticity: Predator-Induced Changes in Wood Frog Tadpoles

Taxa that are divided into separate populations with low levels of interpopulation dispersal have the potential to evolve genetically based differences in their phenotypes and the plasticity of those phenotypes. These differences can be due to random processes, including genetic drift and founder effects, or they can be the result of different selection pressures among populations. I investigated population-level differences in predator-induced phenotypic plasticity in eight populations of larval wood frogs (Rana sylvatica) over a small geographic scale (interpopulation distances of 0.3–8 km). Using a common-garden experiment containing predator and no-predator environments, I found population differences in behavior, morphology, and life history. These responses exhibited a habitat-related pattern; larvae from the four populations from closed-canopy ponds did not differ from each other in all of their phenotypes whereas the four populations from open-canopy ponds did differ from each other in these traits. This phenotype matches the pattern of competitors and predators found in these two types of ponds; based on two years of pond surveys, the four closed-canopy ponds contained very similar competitor and predator assemblages while the assemblages of the four open-canopy ponds were more diverse and highly variable among open-canopy ponds. When combined with past studies, which demonstrate that predators and competitors select for alternative behavioral and morphological traits, these patterns suggest that the population differences may have arisen via natural selection and not via random mutation or drift. In a second experiment, I cross-transplanted two of the populations into each other's ponds to determine if the populations were locally adapted to the conditions of their native pond (using low and high competition crossed with the presence or absence of a lethal predator). The populations continued to exhibit phenotypic differences and one of the two populations tested exhibited superior growth in its native pond. This suggests that some wood frog populations are adapted to the local conditions of their natal pond and that localized selection by predation and competition may be the underlying mechanism. Collectively, these experiments indicate that taxa that are divided into discrete populations and face different predator and competitor environments can evolve different phenotypically plastic responses.

LOCAL POPULATION DIFFERENCES IN PHENOTYPIC PLASTICITY: PREDATOR-INDUCED CHANGES IN WOOD FROG TADPOLES

Taxa that are divided into separate populations with low levels of interpop- ulation dispersal have the potential to evolve genetically based differences in their phe- notypes and the plasticity of those phenotypes. These differences can be due to random processes, including genetic drift and founder effects, or they can be the result of different selection pressures among populations. I investigated population-level differences in pred- ator-induced phenotypic plasticity in eight populations of larval wood frogs (Rana sylvatica) over a small geographic scale (interpopulation distances of 0.3-8 km). Using a common-garden experiment containing predator and no-predator environments, I found population differences in behavior, morphology, and life history. These responses exhibited a habitat-related pattern: the four populations from closed-canopy ponds did not differ from each other in any of their phenotypes whereas the four populations from open- canopy ponds did differ from each other in these traits. This phenotypic pattern matches the pattern of competitors and predators found in these two types of ponds. Based on two years of pond surveys, the four closed-canopy ponds contained very similar competitor and predator assemblages while the assemblages of the four open-canopy ponds were more diverse and highly variable among open-canopy ponds. When combined with past studies, which demonstrate that predators and competitors select for alternative behavioral and morphological traits, these patterns suggest that the population differences may have arisen via natural selection and not via random mutation or drift. In a second experiment, I cross-transplanted two of the populations into each other's ponds to determine if the populations were locally adapted to the conditions of their native pond (using low and high competition crossed with the presence or absence of a lethal predator). The populations continued to exhibit phenotypic differences, and one of the two populations tested exhibited superior growth in its native pond. This suggests that some wood frog populations are adapted to the local conditions of their natal pond and that localized selection by predation and competition may be the underlying mechanism. Col- lectively, these experiments indicate that taxa that are divided into discrete populations and face different predator and competitor environments can evolve different phenotypically plastic responses.

The Relative Roles of Adaptation and Phylogeny in Determination of Larval Traits in Diversifying Anuran Lineages

I measured phenotypic traits important to the fitness of larval anurans to assess the relative roles of ancestral trait value and selective regime in determining present-day phenotypes. The positions of 14 species from three taxonomic families and three different habitats in a phenotypic space defined by 19 traits provided measures of taxonomic and ecological similarity. The distribution of phenotypic distances among species revealed that neither taxonomy nor habitat overwhelmingly determined phenotype. There appear to be multiple ways in which anurans can exploit pond types. However, the direction of phenotypic movement was not random from one species to the next. Independent contrasts revealed significant correlations in the evolution of traits that were consistent among lineages. These correlations reflected well-known trade-offs that result from functional relationships among the constituent traits. Although there is no simple pattern in the distribution of mean phenotypes across environments and lineages, the pattern of the evolutionary trajectories that created that distribution is consistent with a predictive theory of multivariate evolution.

Growth Performance Of Hybrid Bass And Hybrid Tilapia In Conventional And Active Suspension Intensive Ponds

Recently developed, active suspension intensive ponds are based on the idea that fish ponds (aer- ated and mixed as required for the well-being of the fish) can also serve as water purification units. The present paper compares water quality and fish growth in conventional intensive ponds (daily water exchange 500%), with active suspension intensive ponds (daily exchange 8%). The fish test- ed were hybrid tilapia (Oreochromis niloticus x O. aureus), already known to perform well in active suspension units, and hybrid bass (Morone saxatilis x M. chrysops), which is commercially cultured in conventional intensive ponds. Water quality in the two types of intensive ponds differed as a result of the “internal water purifi- cation” vs “external water purification” approach. Bacterial development was greater in the active suspension ponds. Several parameters were affected by the different rate of water exchange, including temperature and removal of ammonium. The latter was lower in active suspension ponds due to reduced washout of particles and their associated nitrifying bacteria. Nitrification was greater in tilapia active suspension ponds because of grazing by this fish. Active suspension units operated with less than 2% of the water used in the conventional intensive ponds. Hybrid bass and hybrid tilapia performed similarly well in both types of pond, indicating the economic advantage of culturing them in the water-saving active suspension system. Tilapia graze on suspended parti- cles, leading to additional savings in feed costs. The good performance of hybrid bass in active suspension ponds is herein reported for the first time. * Corresponding author. Email: anamilst@netvision.net.il 2 Email: agyoram@techunix.technion.ac.il

A comparative study of activity levels in larval anurans and response to the presence of different predators

Activity level is a key behavioral trait in many animals which mediates a trade-off between finding food and avoiding predation. Optimal activity level will therefore depend on environment, and plasticity in response may increase fitness (if an organism encounters multiple environments in a lifetime). One group in which activity level, and its relationship to foraging and predation risk, has been well studied is larval anurans. Anurans inhabit a range of distinct freshwater aquatic community types that are created by differences in pond permanency and top predator. Species segregate across these pond types and therefore tadpoles from different species encounter different selection regimes. I hypothesized that species from different pond types would therefore differ in activity behavior, and in plasticity of this behavior. I tested this in a phylogenetic framework to consider the evolution of plasticity in anurans diversifying into different pond types. Time spent active was quantified for larvae of each of 13 anuran species (from three taxonomic families) in four conditions: when no predator was present, and in the non-lethal presence of a dragonfly, newt, or fish predator. Species nested within pond type by taxonomic family differed significantly in time spent active. A significant interaction between predator treatment and taxonomic family was also observed. A phylogenetic analysis of change in behavior revealed strong positive correlations in evolution of these behaviors and suggests constraints on the ability of larval anurans to independently modify activity levels in the presence versus absence of predators.

Coexistence of helminth species in Lysapsus limellus (Anura: Pseudidae) from an Argentinean subtropical area: influence of biotic and abiotic factors.

The need for studies on helminth communities of South American amphibians was addressed by examining changes in composition and population dynamics of the helminth component and infracommunities in the frog Lysapsus limellus Cope, 1862, from 1994 to 1996. Two pond types were considered, one permanent and one semipermanent. The main goals of this study were (1) to investigate the relationships between pond type, season, study time, frog body size, and frog sex and the presence-absence and counts of helminth parasite species in the frog host, L. limellus, and (2) to examine the co-occurrence of the different parasite species in the frog host in terms of the structure, assembly, and dynamics of the helminth infracommunity. Parasite presence and absence were analyzed using logistic regression and parasite counts were analyzed using log-linear modeling. To examine the association between parasite species, a principal components analysis was carried out on the correlation matrix for the counts. The pattern of co-occurrences was also examined through a randomization test. The main results were as follows: (1) five parasite species were found in the infracommunity; (2) the pond type and the host size class were the principal factors related to the presence and absence of parasites for the three dominant species, while the year of study and the host sex were only important for one of the species; (3) for the parasite counts, many more factors were significant, with body size class and pond type always important factors for the three core species of the infracommunity, with season, year of study, and sex also sometimes important, and (4) strong associations were observed between some helminth species of the host from the permanent pond, but the same species did not co-occur in frogs in the semipermanent pond. The life histories of the five species can be considered as opportunistic or "r strategists."

Groundwater resources development in hard rock terrain - an approach using remote sensing and GIS techniques

To demonstrate the capabilities of remote sensing and Geographic Information System (GIS) techniques for groundwater resources development in hard rock terrains, specifically for the demarcation of suitable sites for artificial recharge of groundwater aquifers, a study was carried out in the Kallar Basin, which is located in parts of the Salem and Tiruchirapalli districts, Tamil Nadu, India. Thematic maps defining lithology, lineaments, landforms, landuse, drainage density, thickness of weathered zone, thickness of fractured zone, hydrological soils, and well yield were prepared from data collected by the Indian Remote Sensing Satellite (IRS) -1C and by conventional methods. All the thematic layers were integrated using a GIS-based model developed specifically for this purpose, enabling a map showing artificial recharge zones to be generated. The exact type of artificial recharge structure, eg, check dam, nallabund, gully plugging and percolation pond, suitable for replenishing groundwater was identified by superposing a drainage network map over an artificial recharge zones map. The GIS-based demarcation of artificial zones developed in the study was based on logical conditions and reasoning, so that the same techniques (with appropriate modifications) could be adopted elsewhere, especially in hard rock terrain, where the occurrence of groundwater is restricted and subject to greater complexity.

The distribution and macrofauna of ponds in stretches of an alpine floodplain differently impacted by hydrological engineering

The purpose of this study was to describe the impact of hydrological engineering on distribution, morphology and macrofaunal community composition of ponds in an alpine floodplain. The study was conducted in 1995 with the study sites being located on the Isar floodplain (Bavaria, Germany). The density of ponds was highest in a bypassed section of the floodplain with a residual flow regime and unrestricted peak floods (up to 40 ponds per river kilometre). In a channelized section and downstream of a reservoir, density was much lower. In 1995, about one third of the ponds were removed by floods or dried out in summer. About the same fraction was generated as a result of flood events. The composition of the macroinvertebrate and vertebrate faunas of 59 ponds was investigated. Cluster analysis classified the ponds into four groups. One of the faunal types was limited to ponds generated by the 1995 floods, where only a few predominantly rheophilic species occurred. The other types represented older successional stages and were inhabited by more species-rich faunas composed mainly of Odonata, Heteroptera and Coleoptera. In the channelized stretch of the Isar floodplain, and downstream of the reservoir only a single pond was generated by the 1995 floods; this caused a lower abundance and diversity of pond types. Copyright © 1999 John Wiley & Sons, Ltd.

Acid Water Anuran Pond Communities along a Regional Forest to Agro-Urban Ecotone

iables in 14 acid water ponds located within drainage areas that displayed a range of agricultural and developed land use cover in the New Jersey Pinelands (Pine Barrens). Species were classified as those restricted to the Pinelands (Pine Barrens species: Hyla andersonii and Rana virgatipes), those with a wide-ranging distribution in southern New Jersey (wide-ranging species: Pseudacris crucifer crucifer, Bufofowleri, Rana sphenocephala utricularius, and Rana clamitans melanota), and those normally unable to enter the Pinelands except in habitats disturbed by human activities (border-entrant species: Hyla versicolor, Pseudacris kalmi, Acris crepitans crepitans, and Rana sylvatica). The frequency of occurrence of Pine Barrens and wide-ranging species was greater than that of any border-entrant species. Detrended correspondence analysis revealed an adult community gradient associated with geographic position where border-entrant species were heard only at ponds located along the transition between forested and disturbed landscapes. Principal component analysis revealed a primary environmental gradient of increasing pH and emergent herbaceous vegetation cover and decreasing specific conductance and floating vegetation cover and contrasted natural and artificial (borrow pits) pond types. Floating vegetation cover and specific conductance were lower and pH was higher in artificial versus natural ponds. Larval recruitment occurred for all species except the four border entrants and B. fowleri. Larval species richness was directly related to emergent herbaceous vegetation cover and inversely related to specific conductance. Our results suggest that landscape patterns influence the distribution of adult anurans, whereas pond chemistry may limit recruitment.

Pond macrophyte assemblages, biodisparity and spatial distribution of ponds in the Northumberland coastal plain, UK

1. Macrophyte assemblages from 50 ponds throughout the Northumberland coastal plain were surveyed together with adjacent landscape, pond morphology and physical and chemical variables. 2. TWINSPAN classification and CANOCO ordinations suggested that, whilst distinct macrophyte assemblages recurred, relationships of assemblages to environmental variables were weak. Geographical variables (northing, easting and altitude) plus extent of drying out were the most important variables in the CANOCO ordination linking pond types and environmental factors. Most assemblages could be found across a wide range of conditions. Classifications using only aquatic or emergent taxa gave different results. 3. Regression analyses suggested that total species richness of aquatic taxa increased with greater area of deeper water and pH. Emergent taxa richness increased with pond area, areas of deeper water and drying down, and decreased with altitude. The level of prediction was weak. 4. Pond types, defined by their macrophytes, were dispersed throughout the region and interspersed so that adjacent ponds often supported different assemblages. No habitat or locale supported unique types or unusual variety. 5. Local, anecdotal classifications of pond types in Northumberland, e.g. ‘subsidence ponds’, proved unreliable. Classification of ponds using macrophytes suggested greater biodisparity than such simplistic categories. The two main approaches to pond assessment (spatial surveys and ecological classification) need to be combined for sound assessment of the local status of ponds. This would benefit regional selection of pond types for conservation. © 1998 John Wiley & Sons, Ltd.

Distribution of external parasites indicates boundaries to the dispersal of sillaginid fishes in the Indo-West Pacific

Pike perch fry (<4 months old) reared in two different types of natural food ponds were examined for parasites in Rauma and at Porla, southern Finland, during June-August in 1990 and 1991. The ponds differed in size and drainage. The highest number of observed parasite species per sample was 11 at Porla and 4 in Rauma. Altogether 4 species of protozoan parasites were detected on the skin and/or gills: Ichthyobodo necator, Ambiphrya ameiuri, Trichophrya piscium and Trichodina sp. The two major species were I. necator and A. ameiuri. The intensity of I. necator infestation was mostly rather low. Infestation by A. ameiuri was very heavy at Porla in 1990. In July, the skin and particularly the fins were filled with this ciliate and the fins were frayed. Ten species of helminth parasites occurred at Porla: Diplostomum sp. (lens), Diplostomum sp. (vitreous humour), Tylodelphys clavata, Bunodera lucioperae, Proteocephalus sp., Eubothrium sp., Raphidascaris acus, Argulus foliaceus, Piscicola geometra and Nematoda sp. Only two helminth species, Diplostomum sp. in lens and Diplostomum sp. in vitreous humour, were found in the pike perch in Rauma. The composition of the parasite species and their influence on cultured pike perch in the natural food pond seemed to be connected to various environmental factors. Some indication was obtained for Ambiphrya ameiuri-induced mortality. The results of this study indicate that drainage of the pond between the growing seasons, minimizing the number of fish species in the pond and having sufficient nutrition are good methods for keeping the parasite load small.