Spatial and seasonal distribution of heterotrophic bacteria in pond water and sediments under different management practices

Population densities and generation time of heterotrophic bacteria were estimated in water and sediments of fish ponds used for polyculture, monoculture and traditional systems of fish farming over a period of two and a half years. Spatial differences in microbial densities in the ponds were related to the organic loadings of the farm site and farm management. A number of environmental factors such as nitrogen, dissolved organic carbon, bicarbonate and phosphate of water were found to be responsible for the seasonal changes of heterotrophic bacteria in these ponds.     

河南安阳平原农耕区鸟类区系及多样性

2009年7月～2011年8月对河南安阳平原农耕区鸟类进行了调查,共记录到鸟类109种,隶属13目33科,其中雀形目鸟类59种,占鸟种总数的54.1%;留鸟30种,占总种数的28.4%;夏候鸟33种,占总种数的30.3%;冬候鸟8种,占6.4%;旅鸟38种,占34.9%。在生境分布上,以村庄农田鸟类种类最多,其次是林地果园,鸟种最少的是河流水域。在调查研究的基础上提出了鸟类保护的一些建议。     

Measurements of some Groups of Microbial Populations with Special Reference to Denitrification in Water and Sediments of Fish Farming Ponds under Mono- and Polyculture Systems

The spatial and seasonal distribution of some groups of bacteria as well as the rates of denitrification (natural and potential) have been investigated in water and sediments of four fish farming ponds under monoculture, traditional and polyculture systems in India. Marked differences in the monthly means of bacteria were found to exist in these fish ponds depending upon their trophic statuses. The seasonal changes of bacteria are discussed in relation to the variation of environmental factors.     

Seasonal and spatial distribution pattern of nitrogen fixing bacteria in fish ponds under different management systems

Enumeration of nitrogen fixing bacterial population in water and sediment samples of six fish farming ponds (polyculture, monoculture and traditional systems) over a period of two and a half years revealed significant differences between the culture systems with maximal and lowest counts in the monoculture and traditional systems, respectively. Polynomial equations of the 2nd to 4th degree were used to represent the observed seasonal data in these ponds. The bacterial populations peaked in summer, while the lowest count was observed in winter. The environmental factors such as pH, different species of nitrogen, dissolved organic carbon were responsible for the seasonal changes in nitrogen fixing bacteria.     

Diversity in Mediterranean farm ponds: trade‐offs and synergies between irrigation modernisation and biodiversity conservation

1. Agricultural intensification has caused dramatic biodiversity loss in many agricultural landscapes over the last century. Here, we investigated whether new types of farm ponds (made of artificial substrata) in intensive systems and natural‐substratum ponds in traditional farming systems differ in their value for aquatic biodiversity conservation. 2. We analysed the main patterns of environmental variation, compared α‐, β‐ and γ‐diversity of macroinvertebrates between ponds types and evaluated the role of submerged aquatic vegetation (SAV). Generalised additive models (GAM) were used to analyse the relationships of α‐ and β‐diversity with environmental predictors, and variation partitioning to separate the effect of environmental and spatial characteristics on the variation in macroinvertebrate assemblages. Moran’s eigenvector maps (MEMs) were used to define spatial variables. 3. A principal coordinate analysis (PCoA) detected a primary environmental gradient that separated nutrient‐rich ponds from those dominated by SAV; a secondary morphometric gradient distinguished natural‐substratum ponds, with large surface area and structural complexity, from artificial‐substratum ponds with steeper slopes. Natural‐substratum ponds had almost twice the α‐ and γ‐diversity of artificial‐substratum ponds, and diversity significantly increased when SAV was present, particularly in artificial‐substratum ponds. Total phosphorus (TP) strongly contributed to explain the patterns in diversity, while SAV was a significant predictor of assemblage composition and diversity. GAMs revealed optima of both α‐diversity at intermediate SAV covers and β‐diversity at intermediate–high TP concentrations. 4. These findings have important implications for conservation planning. Adaptation of artificial‐substratum ponds by adding natural substratum and smoothing the gradient of pond margins would improve their conservation value. Development of SAV with occasional harvests and certain cautionary measures to control nutrient levels may also improve both the agronomical and environmental function of ponds.     

Estimates of Microbial Populations Involved in the N Cycle and their Activity in Water and Sediments of Fish Farming Ponds under Mono and Polyculture Systems in India

The population sizes of ammonifying, protein mineralizing, nitrogen fixing and nitrifying bacteria, and the rates of ammonification and nitrification (natural and potential) were measured in water and sediments of four fish ponds being used for traditional, mono- and polyculture systems of fish farming. Spatial differences in the microbial density in these ponds were related to the fish culturing practices adopted. The seasonal variation of ammonifying bacteria was found to be positively correlated with the NH₄-N level in the water. The natural and potential capacity to generate both nitrite and nitrate in these water bodies was strongly correlated with the concentrations of the different forms of inorganic nitrogen present. The rates of NO₂-N and NO₃-N formation occurring in these fish ponds were directly proportional to the amount of dissolved oxygen and pH of the environment, respectively.     

Farm ponds make a contribution to the biodiversity of aquatic insects in a French agricultural landscape

Manmade ecosystems provide a variety of resources that have strong economic values. We assessed the importance of 37 farm ponds for the biodiversity of Odonata in an agricultural landscape lacking natural wetlands in southwestern France. Farm ponds captured 40% of the regional species pool, including both common and rare species. The species assemblages were not correlated with pond use (e.g., cattle watering, duck farming, etc.) or to landscape variable. Species richness was correlated with pond area, suggesting that community diversity was primarily driven by autoecological processes. Farm ponds thus made a positive contribution to the maintenance of aquatic biodiversity. This added value for biodiversity should be considered when calculating the costs and benefits of constructing water bodies for human activities.     

Status and impact of rural aquaculture practice on Lake Victoria basin wetlands

Rural aquaculture in Lake Victoria basin is a fast increasing nontraditional farming activity which if not appropriately practised will lead to degradation of the wetlands. As part of a study to develop appropriate guidelines and model systems for wetlands‐based rural aquaculture in the basin a survey was conducted to assess the status and the ecological and socioeconomic impact of rural aquaculture on wetlands and wetlands communities. Aquaculture practice was found to be common but not as a major activity. Aquaculture in the wetlands can be described as a low input‐low output production activity and subsistence based on ponds under 400 m² using free seed from public agencies with hardly any supplementary feeding. Men owned most of the ponds and women only contributed to the management of the fishponds by feeding the fish. Poorly constructed ponds and loss during harvesting have led to the escape of cultured species into the wild. Introduction of nonnative species in the basin has already led to wide ranging ecological, environmental and socioeconomic changes whose impact and usefulness are still very much contentious. Repeat of such scenarios can be avoided if appropriate and science‐based models for rural aquaculture farming are developed, tested and disseminated to the communities.     

Epidemic and Endemic Malaria Transmission Related to Fish Farming Ponds in the Amazon Frontier

Fish farming in the Amazon has been stimulated as a solution to increase economic development. However, poorly managed fish ponds have been sometimes associated with the presence of Anopheles spp. and consequently, with malaria transmission. In this study, we analyzed the spatial and temporal dynamics of malaria in the state of Acre (and more closely within a single county) to investigate the potential links between aquaculture and malaria transmission in this region. At the state level, we classified the 22 counties into three malaria endemicity patterns, based on the correlation between notification time series. Furthermore, the study period (2003–2013) was divided into two phases (epidemic and post-epidemic). Higher fish pond construction coincided both spatially and temporally with increased rate of malaria notification. Within one malaria endemic county, we investigated the relationship between the geolocation of malaria cases (2011–2012) and their distance to fish ponds. Entomological surveys carried out in these ponds provided measurements of anopheline abundance that were significantly associated with the abundance of malaria cases within 100 m of the ponds (P < 0.005; r = 0.39). These results taken together suggest that fish farming contributes to the maintenance of high transmission levels of malaria in this region.     

Distribution pattern of sulphate reducing and thiosulphate oxidizing bacterial populations in fish ponds of differing farming managements

The population size of SRB and TOB was enumerated at bimonthly intervals from water and sediment samples of six fish ponds (polyculture, monoculture and traditional systems) over a period of two and a half years. Density of SRB and TOB was maximal in polyculture and minimal in traditional systems of fish farming. Using sine and cosine waves of periodic functions or polynomial equations of high order, seasonal changes in the numbers of SRB and TOB were represented; the former occurred in largest numbers in summer while the latter in winter. Step wise multiple regression analysis revealed that organic carbon, organic matter, phosphate and different forms of N were important attributes to the seasonal changes of SRB and TOB in these fish ponds.     

Wastewater-grown duckweed may be safely used as fish feed

Duckweed has been used for the treatment of wastewater and as fish feed. A comparative study was carried out to determine (i) the efficacy of duckweed in treating hospital-based wastewater and (ii) the level of the microbial contamination of fish fed on wastewater-grown duckweed. There were two groups of ponds where fish farming was done. In one group of ponds (control ponds), duckweed that was grown using artificial fertilizer was used as fish feed; in another group (study ponds), wastewater-grown duckweed was used as fish feed. The faecal contamination of water, duckweed, and fish from study and control ponds were monitored by faecal coliform estimation. The presence of enteric pathogens among handlers, water, duckweed, and fish samples was also examined. It was observed that the faecal coliform counts of raw wastewater were 4.7 Log10 CFU/mL, which was reduced to <1 Log10 CFU/mL after treating with duckweed. There was no significant difference (P > 0.05) in faecal coliform counts in water collected from duckweed ponds and fish ponds of study and control areas. The wastewater-grown duckweed did not pose any health hazard to the handlers. These results demonstrated that the wastewater-treated duckweed may be safely used as fish feed.     

Challenges of a transition to a sustainably managed shrimp culture agro-ecosystem in the Mahakam delta,East Kalimantan,Indonesia

Around 1990, when in other countries mangrove protection took off, massive conversion of mangrove forest into shrimp ponds started in the Mahakam delta. To identify constraints to and options for sustainable management we analysed institutions and constraints with stakeholders. In 3 sites we used participatory tools and a complementary survey to assess the livelihood framework. Since 1970, ponds for shrimp farming gradually replaced 75% of mangrove forested area. After 2004, recovery of mangrove took off, as, mainly due to low shrimp yields, ponds were abandoned. In 2008, 54% of the delta was dedicated to ponds for shrimp production. Around 80% of livelihood activities of pond-farmers, pond caretakers, and fishermen was related to mangroves. The involvement of men and women in these activities varied between sites and types. Poor households depended more on mangroves. Most activities resulted in seasonal income peaks; only a few activities resulted in a full daily livelihood. Ponds, on the other hand, provide 50% of households’ livelihood, but this remains vulnerable in the context of the risky shrimp production. Skewed land holding, unequal sharing of benefits, competing claims and vested interests of stakeholders pose a great challenge to a transition to a more sustainable use of the mangrove area. In particular, ponds located on peat soils are non-sustainable and would require full restoration into mangrove; ponds on other soils could best be transformed into a mixed mangrove-pond system using a ‘green-water’ technology.     

Quantification of Vibrio penaeicida, the etiological agent of Syndrome 93 in New Caledonian shrimp, by real-time PCR using SYBR Green I chemistry

Shrimp farming is a small but growing industry in New Caledonia. Since 1993, "Syndrome 93" has been affecting New Caledonian shrimp farming industry every cold season, causing severe epizootic mortalities in grow-out ponds and significant losses. Highly pathogenic strains of Vibrio penaeicida are considered the etiological agent of the disease in Litopenaeus stylirostris. On one hand, studies demonstrated that healthy shrimp may carry V. penaeicida for weeks with a high overall prevalence, regardless of any seasonal pattern or temperature conditions. On the other hand, larvae are free of V. penaeicida and are also resistant to experimental infection. V. penaeicida is frequently detected in incoming water pumped from the bays, which was shown, by a molecular typing study, to be the infectious source. This particular epidemiological pattern highlights the major role of the factors that trigger and aggravate the disease in grow-out ponds, where shrimp populations carry the pathogen all year round. In order to gain a better understanding of "Syndrome 93" epidemiology, quantification of V. penaeicida both in shrimp and the shrimp farm ecosystem is necessary. This article describes the steps in the successful development of a real-time PCR quantification assay of V. penaeicida in shrimp haemolymph, seawater (from ponds or bays) and sediment pore water, including the choice of an accurate extraction technique. The entire detection method; including sample processing, DNA extraction and real-time PCR amplification, can be completed within 4 h.     

Site selection and regulation issues for trout and carp farming in Germany

In most industrialized countries very few natural freshwater habitats are available for the establishment of new fish farms. These limits require regulatory measures, largely depending on local conditions. Regulations on volume and type or water to be extracted from groundwater and/or surface resources exist in Germany on the ‘Linder’ federal level (contained in the ‘Water Acts’ (‘Wasserhaushaltsgesetz’). These regulations also set water quality criteria for effluent discharge into receiving waters. Site selection criteria are largely determined by the type of aquaculture considered: in extensive, conventional pond farming systems, criteria on natural factors include water resource availability, space and geomorphological (e.g. sloe) and geochemical factors (e.g. soils). The appropriate positioning and leveling of ponds will decide on whether excessive energy costs can be avoided. Different site selection criteria will have to be employed for trout and carp culture. For carp, availability of large areas with suitable soil characteristics is essential. Comparably low yields per unit area will be achievable (productivity of the water determines stocking density and yield). Construction costs need to be kept at a minimum, otherwise the operation will never become economically feasible. Exceptions are special ponds for overwintering, or spawning or other special purposes. Trout culture in earthern ponds require different site selection criteria, depending on the volume of water supply, because yield does not depend on area specific productivity of the water body. Water quality management criteria become an overriding issue for this type of culture system. Stocking density will be determined by the permit for extractable water volumes per unit time. (set by the water authorities). Intensification methods for trout farming exist within the range of regulated effluent standards by using specifically designed system components such as concrete ponds, raceways, circular tanks, aeration, oxygenation, etc. The effluents, however, are considered an industrial waste and their release into receiving waters will be under the water management law (57). If standards are not met within the set limits effluents will be charged as the release of any other industrial wastewater.     

Methanogenic community compositions in surface sediment of freshwater aquaculture ponds and the influencing factors

Aquaculture ponds represent ecologically relevant environments to study the community composition and diversity of methanogenic assemblages, as well as their interactions with cultivated species and chemical indicators. In this study, aquaculture ponds with crab (Eriocheir sinensis), oriental river prawn (Macrobrachium nipponense), perch (Micropterus salmonides) and Wuchang fish (Parabramis pekinensis) were sampled, and Illumina high-throughput sequencing was used to investigate the methanogenic communities. The results revealed that the abundant methanogenic orders in surface sediment were Methanomicrobiales, Methanosarcinales and Methanocellales. The relative abundance of Methanocellales was higher in crab and prawn ponds as compared to other ponds. Methanogenic 16S rRNA gene abundance and beta diversity of the community was affected by the cultivated species. Methanogenic communities in aquaculture ponds with higher contents of total nitrogen and organic matter had decreased species richness, while those with higher contents of ammonia and nitrite had an overall decreased abundance of methanogens and their respective diversities. Overall, in addition to the differences in cultivated species, the consequent differences in farming practices including the types and amounts of feeds used, the contents of total nitrogen, organic matter, ammonia and nitrite could all influence the methanogenic community in surface sediment of aquaculture ponds.     

Spatial and temporal changes of nitrifying bacterial populations in fish ponds of differing management practices

Practices of three types of fish farming (polyculture, monoculture and traditional) resulted in density differences of ammonia oxidizers which occurred in maximal numbers in polyculture and minimal in traditional systems. This distribution pattern was attributed to their nutrient status. The sine and cosine waves of periodic functions were a good fit with the seasonal data showing a sharp peak in winter. The correlation studies revealed that seasonal changes of ammonia oxidizers of these fish ponds were largely dependent upon pH, concentrations of different forms of nitrogen, phosphate, dissolved oxygen, organic carbon and organic matter as well as the ratio of C to N.     

Mangroves and brackishwater pond culture in the Philippines

Around 50% of mangrove loss in the Philippines can be traced to brackishwater pond construction. The decrease in mangroves from 450 000 ha in 1920 to 132 500 ha in 1990 has been accompanied by expansion of culture ponds to 223 000 ha in 1990. The history of fishpond development in the country includes a government-sponsored fishpond boom in the 1950-g and 1960s, the proconservation decade of the 1970s followed by a shrimp fever in the 1980s. Production from brackisshwater ponds has increased from 15 900 mt worth P7.6 million in 1938 to 267 000 mt valued at P6.5 billion in 1990. On the other hand, the maximum valuation of over $11 000 ha^–1 yr^–1 for unmanaged and managed mangrove forests makes them economically on par with the most profitable pond farming systems. The loss of mangrove systems and their varied goods and services is the single most important consequence of brackishwater pond culture in the Philippines. Moreover, intensive shrimp farming is associated with other ecological and socioeconomic effects such as pollution of coastal waters and decline in domestic food crops. New legislation and enforcement of existing laws, conservation of remaining mangroves, massive rehabilitation of denuded mangrove areas, and promotion of sustainable aquaculture and fisheries are recommended.     

Amphibian decline,pond loss and reduced population connectivity under agricultural intensification over a 38 year period

Habitat loss, together with less obvious land-use changes such as intensified farming practice, can have significant adverse impacts on biodiversity. An important factor in determining the ability of species to cope with such changes is their potential to sustain a populations network by dispersal across the landscape. Habitat quality and structure are particularly important for surface-dwelling species with low dispersal abilities, such as amphibians. To assess this ecological function, ponds in a coastal and typically rural area of northern France were surveyed for amphibians in 1974, 1992 and 2011. These repeated surveys yielded different outcomes for different species groups. Three rare species persisted in more or less specialized habitat types. Two moderately common species declined, but kept strongholds in coastal dunes and associated marshes. Five common species with broad ecological niches remained equally widespread. The Northern crested newt declined markedly and the Midwife toad declined dramatically, as did their breeding habitats in vegetated ponds and cattle drinking troughs. One species, the Moor frog, may have gone locally extinct. A model of relative resistance to amphibian dispersal was created for different landscape types, on a scale from 0 (low resistance) to 1 (high resistance). This generated values of 0.23 for pasture, 0.72 for arable and 0.98 for urban and transport. As pasture declined in the study area, while arable and urban/transport infrastructure increased, amphibian dispersal became more difficult. However, dispersal paths proved difficult to evaluate in a patchy landscape like the one surveyed, due to a paucity of spatial signal. Pond loss is a more tractable reason for the observed amphibian species decline than is the quality of intervening terrestrial habitat matrix. In 2011, 22 newly created ponds had species richness in line with pre-existing ponds and this will have counteracted a dwindling metapopulation structure, indicating that habitat creation/restoration can play a valuable role in conservation. The colonization of new ponds may also prove more informative for gauging the potential for amphibian dispersal in the landscape than the preceding decline.     

A differential proteomic approach to assess the effects of chemotherapeutics and production management strategy on giant tiger shrimp Penaeus monodon

The intensification of shrimp farming has been related to the increasing use of chemotherapeutics and potentially suboptimal rearing conditions. For the purpose of assessing the stress level of cultured giant tiger shrimp Penaeus monodon, a proteomic analysis (2D-DIGE) was performed on hemolymph. On the one hand, shrimp were exposed for 7 days to the antibiotics enrofloxacin or furazolidone via feed (4 g kg^?1) under laboratory conditions. On the other hand, shrimp were submitted to enrofloxacin directly in field conditions in Vietnam, for which two different culture systems were distinguished (intensive and improved extensive). No significant different protein abundance pattern was induced by antibiotics under laboratory conditions, while only one protein spot displayed a 1.53-fold reduction in intensity after exposure to enrofloxacin in improved extensive ponds. When we compared the proteome of shrimp bred either in intensive or in improved extensive system, we observed 9 protein spots displaying significant difference in abundance. Among them, 3 spots of hemocyanin were under-expressed in shrimp from improved extensive ponds. At the opposite 2 spots corresponding to Sarcoplasmic Calcium-binding Protein (SCP) were less abundant in hemolymph of shrimp from intensive ponds. These results demonstrate that the very subtle effects of tested antibiotics on patterns of hemolymph protein expression are overwhelmed by the effects of conditions encountered in different production management systems, such as different oxygen and nitric concentrations.