Fishpond System Research Articles

Ecological intensification in multi-trophic aquaculture ponds: an experimental approach

As aquaculture production is increasing considerably, it needs to become more environment-friendly. Based on a participatory process, an ecologically intensive pond system was designed to test three hypotheses: a combination of intensive and extensive areas provides more ecosystem services than an intensive or extensive area alone; coupling a planted lagoon with an intensive pond decreases the latter's environmental impacts and maintains or increases its fish productivity; and using formulated feed in polyculture increases growth of all fish species. To test these hypotheses, we designed a specific integrated multi-trophic aquaculture system composed of a polyculture of common carp (Cyprinus carpio), roach (Rutilus rutilus) and tench (Tinca tinca) and a lagoon planted with macrophytes to filter the water. This pond system was compared with “extensive” (unfed) and “semi-intensive” fishpond systems without a planted lagoon. We measured fish growth performances, water quality, chlorophyll concentrations and water and sediment nutrient contents. We also calculated the mass balance of nutrients. Concentrations of total nitrogen and phosphorus increased in sediments, indicating that nutrients were stored in the ponds, especially in planted lagoon; the planted lagoon decreased phytoplankton development, and limited blooms, but it slightly decreased fish growth performances compared to those in semi-intensive fishponds. The formulated feed supplied clearly increased fish growth performances and the survival rate, and seemed also to increase the use of available nutrients in ponds, which improved the production of overall fish biomass. In conclusion, the planted lagoon provides ecosystem services on nutrients cycling and habitat for natural biodiversity. Improving knowledge about nutrient cycles from formulated feed within the pond food web would be useful to increase the amounts of nutrients converted into fish biomass.

Longterm study of transformation of potentially toxic element pollution in soil/water/sediment system by means of fractionation with sequential extraction procedures

In first part of the paper a review is given on fractionation methodologies by sequential extraction methodologies applied for risk assessment of environmental pollution by potentially toxic elements (PTE). Main sources of PTE release are the mining-, industrial-, agri-food production-, traffic- and communal-waste. In this latter the medical and health care sources may emerge due to therapeutic and diagnostic applications (Ag, As, Au, Ba, Bi, Cd, Ga, Gd, 131I, Ir, Li, Mn, Fe, Os, Pd, Pt, Rh, Ru, Sb, Sn, Ti, V), to nanomedicines, to ayurvedic herbal medicines with possible contaminant PTEs and non-controlled dietary supplements. The magnitude of adverse effects caused by PTEs in the soil-water-sediment system depends on the various chemical species that can arise. Long-term biological impacts are strongly influenced by mobilization-immobilization processes in the aquatic environment. These can be studied through sequential extraction procedures modelling their pathways. In Europe the simplified extraction scheme proposed by BCR in 1993 and modified in 2001 is mostly used for this purpose. By this approach samples are gradually decomposed and four different fractions of PTEs can be identified, i.e.: i) water-soluble and carbonate-bound fraction; ii) fraction associated with reducible Fe- and Mn-oxides; iii) organic complexed fraction and sulphides; iv) fraction soluble in oxidative acids. The sediment-based Certified Reference Material (CRM) BCR 701 was produced to check the accuracy of the fractionation procedure. The standardization process was hindered by methodological problems, i.e.: i) the solvents used in the BCR system do not mirror completely the natural mobilization processes and partly modify the original chemical species; ii) the time demand of the batch leaching extraction steps is exceedingly long (4–5days); iii) the above CRM, certified for the fractionation of Cu, Cd, Cr, Ni, Pb and Zn, is available only for sediment and cannot be applied to other environmental matrices and other PTEs. The studies aimed at improving the BCR methodology are summarized, in particular to: i) develop continuous flow systems; ii) accelerate the BCR leaching steps by sonication; iii) extend the BCR procedure to other environmental matrices (soils, red mud, composts, biofilms) and further PTEs by multielemental (ICP-OES) detection.In second part of the paper a case study is presented for evaluation of long-term changes of the environmental mobility of PTE contaminations in the fish pond system of Gödöllő town. For vertical and horizontal mapping of PTE content of accumulated sediment layers core samples were taken in 1994, 1995 and 2013. In the sediment layers total soluble PTE content was related to the BCR fractionation. The Chernobyl origine radionuclides were detected by γ-spectroscopy. The BCR sequential extraction procedure for tracking the long-term fate of PTE contamination of different origine in surface water/sediment/systems showed a much potential. By repetition of fractionation of PTEs after 20years clearly reflects the change of PTE concentrations in different fractions. The decrease of PTE concentrations can be explained by leaching the most mobile fractions by water exchange over the sediment and/or by remediation activity.

The effects of cessation of fish farming on duck breeding in French fishpond systems

Fishponds are man-made aquatic systems subjected to more or less active management by fish farmers. They also are an important habitat category for waterbirds. In this study, we attempted to assess the consequences for duck breeding of fish farming interruption in a typical French fishpond region, the Forez, where fish production has declined strongly since the 1990s. Duck pair density, a brood: pair ratio and mean brood size were studied in two successive periods, 2010–2012 and 2013–2015, in 19 ponds abandoned for fish farming between 2008 and 2010, and in 34 ponds still stocked with fish among which 17 were harvested every 2 or 3 years and 17 harvested annually. Between the two study periods, a decrease in abandoned ponds was observed in diving duck (Aythya species) and red-crested pochard Netta rufina pair density and for dabbling duck (Anas species) and red-crested pochard brood: pair ratio. A possible explanation is that fish influenced the nutrient level within the aquatic ecosystem through bioresuspension of phosphorus when stirring the sediment for feeding and through nitrogen production by excretions. Decreased brood sizes in ponds still used for traditional fish farming are suggested to be the result of density-dependent predation rates.

Custo de implantação e planejamento de uma piscicultura de grande porte no estado de Mato Grosso, Brasil

Objetivou-se com este trabalho analisar a viabilidade econômica da implantação de uma piscicultura de grande porte no Estado de Mato Grosso, com 174 ha de lâmina d´água em sistema de tanques escavados, utilizando 30 % dessa área com criação do pintado da Amazônia Pseudoplatystoma spp. e 70 % com criação de peixes redondo (espécies e híbridos do gênero Colossoma e Piaractus). Os dados foram coletados diretamente no setor produtivo, em que estão sendo construídos 73 tanques escavados, com sistemas de abastecimento e drenagem individual. Foram determinados ciclo de criação de 12 meses e os seguintes indicadores zootécnicos, para os peixes redondo e pintado, respectivamente: biomassa de estocagem final média de 0,799 kg/m-2 e de 0,802 kg/m-2, conversão alimentar aparente de 1,80 e 1,90, taxa de sobrevivência de 75 % e de 86 %, peso médio final dos peixes de 1,8 kg e de 2,0 kg. Para obtenção do custo total médio de produção do quilograma dos peixes, foi utilizada a metodologia do custo total de produção (CTP). Para análise de rentabilidade foram utilizados os seguintes indicadores: receita bruta (RB), lucro (L), margem de contribuição (MC), valor presente líquido (VPL), período de retorno do capital (PRC) e taxa interna de retorno (TIR). Para instalação da piscicultura serão investidos R$ 8.688.933,24. O custo total médio do quilograma do peixe, produção total e preço de comercialização dos peixes redondo e do pintado da Amazônia serão, respectivamente: R$ 3,51 e R$ 5,14; 972.797 kg e 418.639 kg, R$ 4,00 e R$ 7,00, o qual totalizará lucro de R$ 1.251.628,29 ao ano (US$ 1= R$ 2,23 cotação média em Julho de 2014). Os resultados do VPL, PRC e TIR para o horizonte de 15 anos são, respectivamente, R$ 7.239.606,49; 4,03 anos e 23,4 %. Foi realizada análise de sensibilidade com diversos cenários desfavoráveis, ainda assim todos apresentaram viabilidade econômica.

Determination of tipping points for aquatic plants and water quality parameters in fish pond systems: A multi-year approach

High levels of nutrients in fish ponds by fish farming may cause significant eutrophication leading to a loss in species richness and a decrease of cover of aquatic plants to phytoplankton dominance. This shift can be represented by a tipping point where a significant change in the state of the ecosystem is observed such as a change from high to low aquatic plants species richness and cover. A total of 100 fish ponds were studied during five years in the Dombes region, France, to determine tipping points in aquatic plant richness and cover using chlorophyll α (CHL), water transparency, Total N (TN) and Total P (TP) gradients with two statistical methods. The relationships between tipping points, nutrient loads and yearly variations in weather conditions were also evaluated. Looking at the five years data, tipping points were observed in aquatic plant richness at 6 and 60μg/L for CHL, and at 3.90mg/L for TN concentration; as well as at 70cm for water transparency, but no tipping point was found with TP. For aquatic plant cover, tipping points were observed at 11μg/L for CHL, 2.42mg/L for TN, 0.05mg/L for TP, and at 62cm for water transparency. These tipping points showed a significant decrease of aquatic plant species richness and cover, linked to the nutrient concentrations which drive the competition between the primary producers phytoplankton and aquatic plants. However, tipping points could vary significantly between years. The inter-annual variability may be due to an early occurrence of phytoplankton blooms in some ponds in a year preventing the establishment of aquatic plants, and thus influencing the value of tipping points. Weather conditions influence the competition between primary producers by impacting chlorophyll α and nutrients concentrations. When weather conditions supported increased nutrient concentrations, the development of phytoplankton and aquatic plants was facilitated and tipping points in aquatic plant richness and cover occurred with relatively high values. Thus, a significant decrease of plant cover and richness occurred at higher level of nutrients compared to the other years. In these cases, aquatic plants dominated over phytoplankton for the spring period, and also often during summer. In conclusion, tipping points observed are mainly linked to the competition between aquatic plants and phytoplankton. In shallow and eutrophic systems like fish ponds where nutrients are not a limiting resource, weather conditions act temporarily during spring as the main regulator of this competition.

Helminth Parasites of thePelophylax esculentusComplex (Anura: Ranidae) in Hortobágy National Park (Hungary)

ABSTRACT: The Document, Assess, Monitoring, Act (DAMA) protocol details an approach to integrating information about parasites into large-scale studies of biodiversity, climate change, and emerging diseases. This study represents an effort to put the DAMA protocol into practice. We collected 101 individuals of protected ranid frogs belonging to the Pelophylax esculentus complex during 2012 and 2013 in the Hortobagy National Park (HNP) in eastern Hungary in an area where an inventory of amphibian helminths had been conducted 40 yr previously. Collecting sites included flowing water, a fish pond system, and a wetland marsh system. We found the following helminth species: Digeneans: Diplodiscus subclavatus, Haematoloechus variegatus, Opisthioglyphe ranae, Pleurogenes claviger, Pleurogenoides medians; Nematodes: Oswaldocruzia filiformis, Rhabdias esculentarum; and Acanthocephala: Acanthocephalus ranae. Rhabdais esculentarum is a new species for the Hungarian fauna and P. ridibundus represents a new host reco...

Macroparasites and their communities of the European eel Anguilla anguilla (Linnaeus) in the Czech Republic

This paper summarises the results of parasitological examinations of the European eel Anguilla anguilla (Linnaeus) in the Czech Republic, carried out at the Institute of Parasitology, Czech Academy of Sciences (previously the Czechoslovak Academy of Sciences) within the period of 50 years (1958-2008). Even though this survey is limited to the Czech Republic, it provides extensive data probably incomparable with any other study anywhere regarding the number of eels examined and parasites found. A total of 723 eels was examined from 42 localities that belong to all of the three main river drainage systems in the country, i.e. the Elbe, Danube and Oder river basins. Of the 31 species of adult and larval macroparasites including Monogenea (4 species), Trematoda (3), Cestoda (3), Nematoda (11), Acanthocephala (5), Hirudinea (1), Bivalvia (1), Copepoda (1), Branchiura (1) and Acariformes (1), most of them (30) were recorded from the Elbe River basin. These parasites can be divided into three main groups regarding their host specificity: parasites specific for eels (26%), non-specific adult parasites occurring also in other fishes (61%) and non-specific larvae (13%). The highest number (19) of parasite species was recorded in the Mácha Lake fishpond system in northern Bohemia. The parasite communities in eels from the individual localities exhibited large differences in their species composition and diversity depending on local ecological conditions. The parasite fauna of A. anguilla in the Czech Republic is compared with that in other European countries. The nematode Cucullanus egyptae Abdel-Ghaffar, Bashtar, Abdel-Gaber, Morsy, Mehlhorn, Al Quraishy et Mohammed, 2014 is designated as a species inquirenda.

The unnatural history of Kāne'ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts.

Kāneʻohe Bay, which is located on the on the NE coast of Oʻahu, Hawaiʻi, represents one of the most intensively studied estuarine coral reef ecosystems in the world. Despite a long history of anthropogenic disturbance, from early settlement to post European contact, the coral reef ecosystem of Kāneʻohe Bay appears to be in better condition in comparison to other reefs around the world. The island of Moku o Loʻe (Coconut Island) in the southern region of the bay became home to the Hawaiʻi Institute of Marine Biology in 1947, where researchers have since documented the various aspects of the unique physical, chemical, and biological features of this coral reef ecosystem. The first human contact by voyaging Polynesians occurred at least 700 years ago. By A.D. 1250 Polynesians voyagers had settled inhabitable islands in the region which led to development of an intensive agricultural, fish pond and ocean resource system that supported a large human population. Anthropogenic disturbance initially involved clearing of land for agriculture, intentional or accidental introduction of alien species, modification of streams to supply water for taro culture, and construction of massive shoreline fish pond enclosures and extensive terraces in the valleys that were used for taro culture. The arrival by the first Europeans in 1778 led to further introductions of plants and animals that radically changed the landscape. Subsequent development of a plantation agricultural system led to increased human immigration, population growth and an end to traditional land and water management practices. The reefs were devastated by extensive dredge and fill operations as well as rapid growth of human population, which led to extensive urbanization of the watershed. By the 1960’s the bay was severely impacted by increased sewage discharge along with increased sedimentation due to improper grading practices and stream channelization, resulting in extensive loss of coral cover. The reefs of Kāneʻohe Bay developed under estuarine conditions and thus have been subjected to multiple natural stresses. These include storm floods, a more extreme temperature range than more oceanic reefs, high rates of sedimentation, and exposure at extreme low tides. Deposition and degradation of organic materials carried into the bay from the watershed results in low pH conditions such that according to some ocean acidification projections the rich coral reefs in the bay should not exist. Increased global temperature due to anthropogenic fossil fuel emmisions is now impacting these reefs with the first “bleaching event” in 1996 and a second more severe event in 2014. The reefs of Kāneʻohe Bay have developed and persist under rather severe natural and anthropogenic perturbations. To date, these reefs have proved to be very resilient once the stressor has been removed. A major question remains to be answered concerning the limits of Kāneʻohe Bay reef resilience in the face of global climate change.

Determining tipping points in aquatic ecosystems: The case of biodiversity and chlorophyll α relations in fish pond systems

The management of biodiversity in aquatic ecosystems requires knowing the state of water quality linked to regime shifts in various taxonomic groups. We examine this question by studying the fish ponds in the Dombes region, France. These waterbodies are characterized by a high diversity of species. High levels of nutrients due to certain fish farming practices may cause significant eutrophication leading to loss in biodiversity and a shift from high coverage of aquatic vegetation to phytoplankton dominance may also be observed. The aim of this study is to assess tipping points, thresholds for effect, along a gradient of chlorophyll α in different taxonomic groups: aquatic vascular plants, phytoplankton, dragonflies and aquatic macro-invertebrates. Tipping points are analyzed with three different statistical methods: a method which evaluates tipping points with a difference in the mean (TMEAN), a second method which evaluates tipping point by comparing the mean and linear regressions before and after the tipping point (FSTAT) and third a method which evaluates linear regressions with a pivotal tipping point (SEGMENTED). We also compare tipping points for the different taxonomic groups using five different diversity indices: Observed richness, Jackknife first order, Fisher's alpha, Simpson index and Evenness.Our results show that there is an important variation in tipping points following the three statistical methods, but the SEGMENTED is the best method for evaluating tipping points. We observe a high difference of tipping point values for the different taxonomic groups depending on the diversity indices used. Jackknife first order has a better performance to evaluate a eutrophic change according to the diversity than the other indices.In all taxonomic groups, aquatic vascular plants are the most impacted by the chlorophyll α and almost all their tipping points are observed around 60μg/L chlorophyll α concentrations. No significant relationship is found between chlorophyll α and phytoplankton diversity, while the two other groups, dragonflies and macro-invertebrates, are both impacted by the chlorophyll α but their relevant tipping points are situated in higher values than aquatic vascular plants.

Aplikasi Simulasi Tambak Ikan Berbasiskan Mobile untuk Meningkatkan Minat Kewirausahaan

The background of the research is that mobile phone based application growth is not as increasing as its education category for improving users’ entrepreneurial-interest, especially in fishpond. The goal of the research is designing an application as a digital game based education tool that can simulate fishpond to users. Output of the research is a mobile application that can deliver information of fishpond system as basic entrepreneurship knowledge to users. On the development phase, the research uses literature study and user requirement analysis. Conclusion of the research has shown that the developed application is based on multimedia and game and also can deliver basic information of fishpond to users such as preservation, purchasing, and selling. The application is developed with good-looking interface and easily-covered level of difficulty.

Using biodiversity to valorise local food products: the case of fish ponds in a cultural landscape, their biodiversity, and carp production

Today, we need to produce sufficient food and simultaneously conserve biodiversity. But, could biodiversity associated with certain food production practices also be used in marketing products? We analyse this possibility for creating a food quality label for carp raised in the Dombes territory, a cultural landscape of fish ponds in France. The biodiversity of 99 fish ponds was studied in the Dombes territory by analysing aquatic vegetation, dragonflies, amphibians, macroinvertebrates, habitats around ponds, and water quality. In addition, a survey with 200 questionnaires and interviews was conducted with consumers to investigate fish and carp consumption and knowledge about quality labels and biodiversity. Findings reveal that fish production practices conserve remarkable species diversity, particularly for aquatic vegetation, dragonflies and amphibians, and habitats around the ponds. This relatively high level of biodiversity is found in spite of having very nutrient-rich fish pond systems, systems for which normally a low level of biodiversity is expected. Nevertheless, currently this biodiversity cannot be valorised for setting up a quality label for locally produced carp. Firstly, few consumers have adequate knowledge about carp and are interested in eating it. Secondly, most of them have less knowledge about the quality label which wanted to be established for carp from the Dombes. Thirdly, only less than one-third of the consumer is familiar with the term “biodiversity”. Fourthly, the stakeholder network of the supply chain is presently not able to communicate the message of biodiversity as they themselves lack a sufficient knowledge about biodiversity of their systems.

Population date of Great Cormorant at the area of the Hortobágy Fish Farm Co.

Hungary’s great cormorant stock did not use to be a considerable one before the 1980s. After that, their number has been rising significantly. The size of the stock now is rather stagnating or slightly growing. The presence of cormorants has been significant around ponds of the Hortobágy Fish Farm in the past few years. Due to considerable fish consumption of cormorants it is essential to know which and what kinds of units of the ponds (spawning, supply, and market) are preferred by the birds in order to see to adequate protection. The aim of our research was to discover any differences in the number of cormorants present at particular units of the fishpond system and certain ponds of equal kinds within them.
 Our observations were in line with the methods used in ornithological researches. The experiment took place between April and October 2012 on a monthly basis. According to the results we found relevant differences in the number of cormorants based on the seasons and months as well. This fact was supported by statistical data. During the autumn and winter birds prefer supply and market purpose ponds while their presence here is vanishing during the summer. Relevant presence of cormorants around the area of the Old Fishponds (70 to 200 specimens) might be due to lack of disturbance and large sizes of the ponds.
 Our research has great scientific relevance since it is vital to be aware of the preferred periods and areas in order to maintain effective protection; this way alerting activities can be applied in a more harmonized way. By keeping our research up as a monitoring activity, we will be able to receive more precise data later on.

Breeding-season dispersal of male and female Penduline Tits (Remiz pendulinus) in south-western Poland

Dispersal during the breeding season is common among multiple-brooding bird species. such as the Penduline Tit Remizpendulinus, in which both sexes are sequentially polygamous and one or both parents may abandon the clutch. Penduline Tits were studied at a large fishpond system in south-western Poland over six breeding seasons (2004-2008 and 2011). Breeding dispersal of 97 males and 44 females were recorded. Females dispersed longer distances than males, and dispersal distances of both males and females did notvary significantly between years. Mating success at the previous nest did not influence the dispersal distance of males. Females who found new mates after a successful breeding attempt settled closer than those who had abandoned their previous nest. The distances of females remating after nest failure were similar to those of abandoning females. These results corroborate the general pattern of dispersal in birds, in which females commonly disperse further than males. This bias can be explained by a sex-dependent difference in breeding-site availability. Male Penduline Tits attract females to their nests and can choose from all vacant sites to settle, whereas females are restricted by males' dispersion and may be forced to go further.

Biodiversity and fish farming intensification in French fishpond systems

Fishponds are artificial ecosystems in which biodiversity may be strongly affected by fish farming management. We studied biodiversity variation along a gradient of fish farming intensification within a 180-pond sample of a French region to establish whether biodiversity primarily depended on extensive management with the alternative hypothesis that some habitat characteristics could compensate for the effect of intensification. We compared the relationships of three biodiversity indicators (breeding birds, protected plants, macrophytes) to an index of intensification and to habitat characteristics likely to influence each indicator. In all selected indicators, species richness did not vary according to the composite intensification gradient. Protected plant richness was best explained by periodic drainage, which could thus benefit biodiversity in intensified fishponds provided that shallow littoral areas are still present. Bird richness was linked to macrophyte cover and probably to reed bed areas. Macrophyte richness and coverage were negatively influenced by low water transparency and high fish biomass which seemed likely to affect bird habitat above 350–400 kg/ha. Aquatic vegetation, which may reflect interactive effects of environmental factors and fish farming management, may then contribute to assessment of the ecological status of fishponds under the E.U. Water Framework Directive.

STUDI PENGEMBANGAN BUDIDAYA IKAN SISTEM KOLAM AIR DERAS DI SUNGAI CARAMELE KOTA PAREPARE SULAWESI SELATAN

Caramele river as upper of karajae river in the parepare city potencial development running water fish pond culture and integrated of tourism and environment sustainability resource. This aimed study to evaluated technical and non technical feasibility aspect arounded karajae river for running water fish pond system. The study used purpose sampling method and variable investigated include; (1) water quality (temperature, velocity, vegetation, soil texture, bentic organism, oxygen,pH,accesability, etc.), (2) environment and social economic impact for native people in the around area. Investigation area fixed three station. The result of the study revealed that feasibility each stations appromixately are Station I (71,3%), Station II (71,3%) and Station III (71,0%). The stations feasibility for development of running water fish pond system are Station I and II.

Environmental impacts of farms integrating aquaculture and agriculture in Cameroon

In sub-Saharan Africa, fish constitutes the main source of animal protein for human consumption. Producing fish in ponds fertilized by manure could help to diversify family-scale agricultural production in this region. Life Cycle Assessment (LCA) could improve understanding of the contribution of fish-pond systems to regional sustainable development. The study analyzed four farms that integrated fish farming with other agricultural production, and in which fish ponds were fertilized either by pig manure and/or crop by-products, in two regions of the western highlands of Cameroon (5–7°N, 9–11°E), Alou and Fokoué. LCA was conducted using the CML2001 characterization method, adapted to aquaculture production, with one tonne of fresh fish at the farm gate as the functional unit and background data from the ecoinvent® database. Dynamics of nitrogen (N) and phosphorus (P) were evaluated using a nutrient mass-balance modeling approach, which showed that low quantities of N and P were assimilated by the fish in these systems. Eutrophication impact was higher for these Cameroonian farms than that of other aquaculture systems in the literature, mainly due to the pig manure and wheat bran used to supply nutrients. Water and nutrient management will need to be improved to increase efficiency of these fish farms.

Heavy metal pollution assessment through comparison of different indices in sewage-fed fishery pond sediments at East Kolkata Wetland, India

The sediments of the raw sewage-fed fishpond system at East Kolkata Wetland (EKW) were analyzed for heavy metal content in a comprehensive way. Various indices of contamination like enrichment factor (EF), geo-chemical index (Igeo), modified degree of contamination (mDC), and pollution load index (PLI) were assessed. In all cases, instead of literature values, the metal concentrations of less contaminated sites, separated by the statistical approach of the hierarchical cluster analysis, were used as baseline values. In the present study, about 70% of the pond sediments are found uncontaminated, 5% display low degree of contamination and 25% are designated as moderate degree of contamination. Both the EF and Igeo indices highlighted that the metals lead (Pb), cadmium (Cd), and chromium (Cr) are responsible for the contamination while there is little anthropogenic input in cases of Cu, Zn, and Ni. Most of the ponds situated near the main sewage flowing canals as well as the main traffic highway and close to the solid waste dumping areas recorded higher degree of metal contamination as evident from spatial variation of mDC and PLI indices in the study area. Indices comparison study clearly indicates that although these are calculated using different methods, these may or may not produce the same indices values and hence the values should neither be compared nor be averaged. But all the above indices are directly related to a common term contamination factor (CF). Classification of contamination levels based on these CF values is found to be similar and this classification is only valid up to the level of high degree of contamination. Thus, the use of any one of these indices is sufficient to classify the degree of contamination of an area. However, to evaluate the contamination per metal, both Igeo and EF are effective while, to assess the composite effect of all the metals, PLI is preferable to mDC.

The role of historical fishpond systems during recent flood events

Most of the large pond systems in the Czech Republic were built in 16th century. One of the most important fishpond systems is the one of the Třeboň basin (Třeboň fishpond system – TFS). It is situated in South Bohemia in the upper Lužnice watershed, but the whole system also includes the upper watershed in Austria. The system consists of almost 1000 fishponds with a total area of 7 500 ha. Retention capacity of fishponds is estimated to be as big as 50–70 mil. m, but might be even 110–140 mil. m during extreme floods. The situation is then often beyond control and damage occurs, which deteriorates the fishponds water management function. The largest is Rožmberk fishpond (480 ha), which stored 50–70 mil. m during the 2002 flood while its normal volume is about 5.5 mil. m. In order to ensure a satisfactory flood retention capacity of fishpond systems, proper maintenance of their technical equipment is necessary and emergency measures for the whole system should be

Influence of fish-farming management on duck breeding in French fish pond systems

Fish ponds host a relatively important share of the breeding population of waterfowl in Europe. The objective of this study was to investigate the influence of fish-farming management on the distribution of dabbling and diving duck breeding, in 103 fishponds from four regions important for duck breeding in France. Duck breeding in fish ponds was apparently influenced by food resource and nesting site availability. Dabbling duck pair density was generally higher when invertebrates were abundant in macrophytes beds and when competition for food with carps Cyprinus carpio was potentially decreased by lower fish stock biomass. Diving duck pair abundance seemed to be negatively influenced by low invertebrates biomasses in pond sediment and by the absence of large reed beds at the edge of waterbodies. The difference between dabbling and diving ducks was also confirmed by a study of the variation in brood numbers standardized by pair numbers. This brood:pair ratio corresponded to a measure of nesting success and the possible attraction of fish ponds for some broods hatched in neighbouring waterbodies. Dabbling duck brood:pair ratio was lower in one of the study regions where most of meadow areas surrounding fish ponds have been transformed into cereal crops in the past few decades. Diving duck brood:pair ratio was positively linked to pond fertilization due to fish farming. Fish farming, therefore, influenced duck breeding by an interaction between carp density and fertilization. We hypothesize that fertilization increases zooplankton density, thereby decreasing the competition between carps and waterfowl for benthic prey.

Genetic structure of otter ( Lutra lutra) populations from two fishpond systems in Hungary

Genetic structure of otter ( Lutra lutra) populations from two fishpond systems in Hungary