Commercial Fish Ponds Research Articles

Comparative Analysis of Cyanotoxins in Fishponds in Nigeria and South Africa

Over the decades, the aquaculture sector has witnessed substantial growth, contributing significantly to the nation’s economy. However, the menace of CyanoHABs threatens the sustainability of fish farming. Considering the possible hazards linked to cyanotoxins in food and water, a comparative study design between commercial fish in Nigeria and South Africa was employed to investigate cyanotoxins in the water from fishponds. Six commercial fishponds in Calabar Municipality—Nigeria and Duthuni—South Africa with varying climatic zones were selected. Water samples from the ponds were collected at intervals during different seasons (summer, winter, dry, and wet seasons) to capture climate-induced variation. Liquid chromatography–mass spectrometry (LCMS) in combination with the metabolites database was used for the identification of toxic cyanometabolites in water samples. The molecular networking approach, coupled with the Global Natural Products Social Molecular Networking (GNPS) database and CANOPUS annotation, enabled the putative identification of cyanometabolites. The resulting molecular network unveiled discernible clusters representing related molecule families, aiding in the identification of both known cyanotoxins and unfamiliar analogues. Furthermore, the molecular network revealed that water samples from different fishponds shared specific metabolites, including ethanesulfonic acid, pheophorbide A, cholic acid, phenylalanine, amyl amine, phosphocholine (PC), and sulfonic acid, despite variations in location, local climatic factors, and sampling sites. The fishponds in Nigeria showed the presence of multiple cyanotoxin classes in the dry, wet, and summer seasons in the water. Aflatoxin was identified in all sampling sites in Nigeria (N1, N2, and N3). The Duthuni, South Africa, sampling sites (P1, P2, and P3) exhibited the presence of microginins and microcystins. All the fishponds displayed a widespread occurrence of anabaenopeptins, aplysiatoxins, aflatoxin, microcolins, and marabmids during the selected summer. In conclusion, the untargeted metabolome analysis, guided by GNPS, proved highly effective in identifying both toxic and non-toxic metabolites in fishponds.

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Heavy metal pollution is a serious environmental problem in freshwaters, potentially impacting public health, water quality and ecosystem integrity worldwide. However, the potential public health risks associated with heavy metal accumulation in water, sediment and commercial fish samples remain unclear. Here we assessed the concentrations and distribution of five heavy metal of public health importance (Iron, Copper, Zinc, Lead and Copper) in water, sediment, and edible organs (muscles, liver, gills, and intestines) of the African sharptooth catfish, Clarias gariepinus obtained from aquaculture ponds. Water, sediment, and fish samples were randomly collected from commercial fishponds across different five locations in Ondo. Metal concentrations in water, sediment and fish samples were analyzed using Atomic Absorption Spectrophotometry (AAS, Model AA-680/ Shimadzu). Mean metal levels observed in water, sediment and fish samples were compared with recommended regulatory guidelines for human consumption. Our results showed mean concentrations for all metals in water exceeded recommended permissible limits in freshwater bodies and aquatic biota, presumably suggesting potential risks for human consumers. Heavy metal levels in sediment samples indicated Fe was maximally accumulated, followed by Zn, Cu, Pb, and Cd. The highest and least accumulations for all the metals were recorded in the gills, and in the liver respectively. Higher concentrations of metals observed in gills corroborate the fact that the gill is a major route for heavy metal accumulation in fish whereas the reduced concentration of metals observed in the liver may be associated with enhanced detoxification mechanism in the liver. These results suggest that fish obtained from these aquaculture ponds may be unsafe for human consumption. Hence, we recommend a periodic assessment of heavy metal levels in commercial fish samples as a major regulatory priority.

Quality Evaluation of Commercial Fish Ponds in Uli, Anambra State and Their Health Implications

Quality Evaluation of Commercial Fish Ponds in Uli, Anambra State and Their Health Implications

Spraints demonstrate small population size and reliance on fishponds for Eurasian otter (Lutra lutra) in Hong Kong

AbstractLack of data on population sizes and resource requirements are major impediments to the effective conservation of rare species globally. The conservation of the Eurasian otter (Lutra lutra) in Hong Kong reflects many of these key challenges for elusive and difficult‐to‐study mammals. It is a rare carnivore that has narrowly escaped extirpation, now surviving within a human‐dominated environment. Using sign surveys and spraint analysis, we recorded only 40 fresh spraints from 246 otter signs locations, over 4 months of intensive sampling across 2 years. Records were restricted to the Mai Po wetlands, confirming this as the core area for Hong Kong's otter population. Molecular analysis and microsatellite genotyping identified a minimum of seven individuals, two pairs of which were likely related. The genetic and sign data together strongly indicate a small population. Fish dominated the otter diet, highlighting the importance of fishpond habitats as a premium foraging resource. Given the rapid changes surrounding the Mai Po area (especially the new Northern Metropolis Development Strategy), maintaining quality and connected habitats, in addition to sustaining commercial fishponds will be key to otter recovery and long‐term population viability in Hong Kong.

Experimental Biology in Conflict Resolutions: The Case of Pelicans and Cormorants in Israel

In Israel, which is a bottleneck for some six hundred million migrating birds, the drainage of the Hula Lake in the north resulted in serious conflicts between fish-eating birds and the intensive fish farming and agriculture that became established on the reclaimed land. Implementation of various deterrence methods, including lethal control, failed to solve these conflicts. We followed the concept that only by understanding the biology of the organism in question could the tools (indications) for effective and sustainable management be devised that would solve such conflicts while helping the preservation of natural assets such as wetlands and their inhabitants. We demonstrated this concept in the solutions reached in the case studies of pelicans and cormorants and their interactions with intensive commercial fish ponds. We studied the physiological condition, food preference and energy demands, and ecological constraints of Great White Pelican Pelecanus onocrotalus, Great Cormorant Phalacrocorax carbo and Pygmy Cormorant Microcarbo pygmeus. As a result, we suggested different management solutions that are currently implemented with the full cooperation of the fishermen and the nature preservation authorities. Based on assessment of visual acuity to detect and catch fish under water Great Cormorants were effectively pushed towards Lake Kinneret where they could hunt more profitable fish than in the turbid fish ponds. The established roosts there were not controlled such as to lead the birds away from the fishponds. In case of the pelicans, part of the drained Hula valley was reflooded and extra fish was provided. Both measures effectively reduced the damage at the fish farms. We have shown that such solutions are economically helpful for fishermen and enable the preservation of the wetland habitat.

EFFECTIVENESS OF EICHHORNIA CRASSIPES IN THE TREATMENT OF AQUACULTURE EFFLUENT FROM A FISH FARM IN BENIN CITY, NIGERIA

Aquaculture production has seen much increase in Nigeria in recent times due to the rise in fish farming occasioned by the availability of water and materials for setting up, the profit turn-over, increase in demand for fish, and the effort to curb the rising youth unemployment rate. However, this massive surge of interest in aquaculture and fish farming is accompanied by the challenge of pollution as the effluent from aquacultural settings gets discharged into nearby water bodies hence the need for remediation. Aquatic plants have been used to remediate polluted water bodies and possess many advantages over other methods. Therefore, this study aimed to investigate the effectiveness of Eichhornia crassipes in the clean-up of aquaculture effluent. Wastewater collected from a commercial fish pond in Benin City, Nigeria, were divided into two treatment groups. One group was diluted with an equal volume of distilled water (50%), and the other group consisted of 100% wastewater. Distilled water was used as a control (0%). The samples were treated with Eichhornia crassipes for 14 days, following which samples were collected for physicochemical analysis. The result showed that E. crassipes reduced significantly the pH from 7.44 to 5.98 and 7.28 to 6.10 in the 50% and 100% effluent samples, respectively. The removal efficiency of E. crassipes in the 100% effluent sample was 69% for phosphate, and 94% for nitrate. The study suggests that E. crassipes may be effective in improving the quality of aquaculture wastewater.

Spatial ecology of little egret (Egretta garzetta) in Hong Kong uncovers preference for commercial fishponds.

Many natural wetlands have been converted to human-influenced wetlands. In some instances, human-influenced wetlands could provide complementary habitats for waterbirds, compensating for the loss of natural wetlands. Inner Deep Bay in Hong Kong is composed of both natural and human-influenced wetlands and is under immense development pressure. From an ecology perspective, we need to understand if different wetland types play the same ecological role. To achieve this, we tracked nine little egrets (Egretta garzetta) using GPS loggers for 14 months to study their spatial ecology, home range, movement and habitat use. We found that over 88% of the home range of all individuals comprised of wetlands (commercial fishponds, mangrove, gei wai, channel, and intertidal mudflat). Among these wetland types, nearly all (seven of nine) individuals preferred commercial fishponds over other habitats in all seasons. Little egrets exhibited seasonal movement and habitat use among seasons, with largest home range, greatest movement, and most frequent visits to commercial fishponds in winter compared to spring and autumn. Our results highlight the significant role of commercial fishponds, providing a feeding ground for little egrets. However, other wetland types cannot be ignored, as they were also used considerably. These findings underscore the importance of maintaining a diversity of wetland types as alternative foraging and breeding habitats.

The Isolation of Antimicrobial Resistant Aeromonas spp. from Aquaculture Samples and their Susceptibility to Medicinal Plant Extracts

Aeromonas spp, ubiquitous in both terrestrial and aquatic environments are becoming renowned as enteric pathogens of serious public health concern as they have a number of virulence and resistant determinants that are linked to both human and aquatic diseases due to consistent and incorrect use of antibiotics in aquaculture. The effect of crude aqueous and ethanol extracts of some medicinal plants on antimicrobial resistant Aeromonas spp. isolated from aquaculture water and fish samples was studied. Two hundred and forty (240) Aeromonas isolates, made up of 168 Aeromonas hydrophila and 72 Aeromonas salmonicida, were recovered from aquaculture water and fish gill samples collected from different commercial fish ponds using selective media. The isolates were assessed for their antibiotic susceptibility against ten (10) conventional antibiotics using the Kirby-Bauer technique. Extracts from three medicinal plants, Vernonia amygdalina, Ocimum gratissimum and Garcinia kola were also analyzed for their antimicrobial effects on the isolates that were resistant to the conventional antibiotics. Aeromonas hydrophila isolates expressed the highest resistant rates of 100%, 78.6% and 70.8% to aztreonam, cefotaxime and neomysin respectively, and the A. salmonicida isolates also had a similar trend of high resistant rates of 100%, 87.5% and 77.8% to aztreonam, neomysin and cefotaxime respectively. Antimicrobial resistant analyses with the plant extracts showed 100% inhibition of the isolates at 100 mg/ml for both aqueous and ethanol extracts. Phytochemical screening identified the presence of certain phytochemicals like alkaloids, saponins, tannins, flavonoids, steroids and glycosides which could have accounted for the antimicrobial effects of the plant extracts under study. It can be inferred then, that extracts from Vernonia amygdalina, Ocimum gratissimum and Garcinia kola can inhibit resistant aquaculture Aeromonas isolates and so can present an alternative source of antimicrobials in the effort to combat the increasing incidence of antimicrobial resistance in aquaculture.

Fish Pond Effluent Effect on Physicochemical Properties of Soils in Southern Guinea Savanna, Nigeria

This work studied the effect of fish pond wastewater, proximate and mineral analyses of the fish feeds from commercial fish ponds on receiving soils in the southern Guinea Savanna ecological zone of Minna, Nigeria. The study con-ducted during the dry seasons of the years 2015 and 2016 between January and May. Four sets of soil samples were collected at varying distances from the various fish ponds and analysed for physicochemical properties, Particle size analysis and Exchangeable Acidity. Similarly, two different sets of water samples were collected each from various farms studied and analysed for physicochemical properties such as pH, Ec (Electrical conductivity), TDS (Total dissolved solids), Alkalinity, Total Hardness, Turbidity, Temperature, DO (Dissolved Oxygen), BOD (Biological oxygen demand), Calcium, Magnesium, Sodium and Potassium. Average results obtained for the two dry seasons for the soil samples around the fish farms showed that: pH 6.33 - 7.24, Organic Carbon 2.03 - 6.00 g/kg, Available Phosphorus 7 - 10 mg/kg, Total Nitrogen 0.95 - 2.10 g/kg, Exchangeable Bases and Exchangeable Acidity 0.02 - 0.06 Cmol/kg were within the permissible limits of FAO and WHO. The various parameters were within the permissible limits for fish production. The fish wastewater had Electrical Conductivity 118 - 230 μS/cm, pH 6.79 - 7.10, and Biological Oxygen Demand 3.0 - 6.0 mg/L. In conclusion, the wastewater from fish farms is good sources of fertiliser to the surrounding farmlands.

Chitosan from crustacean shell waste and its protective role against lead toxicity in Oreochromis mossambicus

In the current study heavy metal removing capability and antioxidant properties of chitosan supplemented diet tested in lead poisoning induced Oreochromis mossambicus in comparison with and standard fish diet. O. mossambicus fishes weighed (20 ± 2gm) were purchased from a local commercial fish pond and acclimated to the laboratory conditions for 10 days. After that fish were dived into four groups, each group received respective feed throughout the experimental period. The fish fed with standard diet exhibited drastic weakening of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GR), glutathione peroxidase (GPx), ascorbic acid, α- tocopherol and β-carotene and also displayed abnormal histological changes in gills, liver, and intestine. The fish fed with a chitosan supplemented diet for 10 days showed substantial enhancements in antioxidant levels and also normal histological structures of organs in the fish.

Comparative Assessment of Some Biochemical Indices in Catfish from Rivers, Swamp and Commercial Fish Ponds in Oil and Non-Oil Polluted Areas in Rivers and Anambra States

Comparative Assessment of Some Biochemical Indices in Catfish from Rivers, Swamp and Commercial Fish Ponds in Oil and Non-Oil Polluted Areas in Rivers and Anambra States

Comparative Analysis of Metal Levels in Clarias gariepinus and Water from River Benue and Commercial Fish Ponds in Makurdi

Comparative Analysis of Metal Levels in Clarias gariepinus and Water from River Benue and Commercial Fish Ponds in Makurdi

Preparation for the Final Testing of the Sprayed Bentonite Sealing Layer of a Pond Dam

This paper presents research conducted on the development of a bentonite material suitable for the sealing of the dams of large ponds used for commercial fishing purposes. It is intended that the material will be applied using spray technology. The research was motivated by the large number of very old commercial fish ponds in the Czech Republic of which some are nearly a thousand years old. With the passage of time, leakage through the dams leads to the creation of caverns and preferential flow paths which may eventually result in a breach in the dam wall. An efficient technological approach to the sealing of these earth structures may, therefore, help to mitigate the risk of their failure and destruction. A potentially suitable material for this purpose has been researched and developed at the Czech Technical University and is now ready for the experimental testing phase involving the construction and study of a physical model of such a dam constructed according to the geometry of traditional commercial fish ponds.

Involvement of aurantiactinomyxon in the life cycle of Thelohanellus testudineus (Cnidaria: Myxosporea) from allogynogenetic gibel carp Carassius auratus gibelio, with morphological, ultrastructural, and molecular analysis

During the investigation of actinosporean fauna diversity from commercial fish ponds in Hubei Province, China, a novel aurantiactinomyxon type was found from Branchiura sowerbyi. Spore body of the aurantiactinomyxon was ellipsoidal in side view and triangular in apical view, 15.5±0.5 (14.5-16.4) μm in diameter; three leaf-like caudal processes were approximately equal, measuring 13.2±0.9 (11.5-16.2) μm long and 7.4±0.4 (6.7-8.0) μm wide at the base; three polar capsules were located at the apex of spore body, globular in apical view, 2.2±0.1 (2.0-2.3) μm in diameter, and pyriform in side view, 2.5±0.2 (2.3-2.9) μm in length and 2.0±0.2 (1.8-2.4) μm in width; a total of 32 germ cells were observed within the sporoplasm. Ultrastructural analysis showed that the development was asynchronous between pansporocysts but synchronous within a pansporocyst. The formation of sporoblast and the development of sporogonic stage were also described and discussed. The 18S ribosomal DNA sequences of the current aurantiactinomyxon type corresponded to that of a previously reported Thelohanellus testudineus, suggesting that the newly identified aurantiactinomyxon type is the actinosporean stage in the life cycle of T. testudineus.

Calculation of metabolic waste of Clarias gariepinus and Tilapia niloticus obtained from two commercial fish ponds in Gwagwalada

An automated blood serum chemistry analytical system designed for human usage was employed to establish the levels of urea and creatinine parameters present in sera obtained from 60 experimental groups of catfish and tilapia from a commercial pond with length ranging from 10 to 58 cm and weight ranging from 98.2 to 900.2 grams (For the first group) and 6.8-5 cm and 28.9-90.5 g (for the second group) respectively. The present study was carried out to determine the result of Urea and Creatinine values of Clarias gariepinus and Tilapia niloticus obtained from two commercial ponds in Gwagwalada. The results observed from catfish when compared to that of tilapia, showed a slight difference of both species. Highest Creatinine value recorded for Clarias gariepinus was 1.53 mg/dl and the lowest was 0.00 mg/dl. While the highest Urea level recorded is 10.4 mg/dl and minimum was 0.04 mg/dl. Highest Creatinine value recorded for Tilapia niloticus was 1.43 mg/dl while the lowest value recorded is 0.02 mg/dl. Urea highest value recorded is 11.40 mg/dl and lowest value is 0.02 mg/dl. The ratio of urea to Creatinine was very high for both species and can be concluded to be either as a result of gastrointestinal bleeding, kidney failure, high protein diet as well as pollution of pond water with substances such as ammonia, and urea which are excreted by fish. It is therefore important to regularly change water to control the effect Urea blood level.

Contribution of fish farming ponds to the production of immature Anopheles spp. in a malaria-endemic Amazonian town

BackgroundIn the past decade fish farming has become an important economic activity in the Occidental Brazilian Amazon, where the number of new fish farms is rapidly increasing. One of the primary concerns with this phenomenon is the contribution of fishponds to the maintenance and increase of the anopheline mosquito population, and the subsequent increase in human malaria burden. This study reports the results of a 2-year anopheline abundance survey in fishponds and natural water bodies in a malaria-endemic area in northwest Brazil. The objective of this study was to investigate the contribution of natural water bodies (rivers, streams, creeks, ponds, and puddles) and artificial fishponds as breeding sites for Anopheles spp. in Mâncio Lima, Acre and to investigate the effect of limnological and environmental variables on Anopheles spp. larval abundance.MethodsNatural water bodies and fishponds were sampled at eight different times over 2 years (early, mid and late rainy season, dry season) in the Amazonian town of Mâncio Lima, Acre. Anopheline larvae were collected with an entomological dipper, and physical, chemical and ecological characteristics of each water body were measured. Management practices of fishpond owners were ascertained with a systematic questionnaire.ResultsFishponds were four times more infested with anopheline larvae than natural water bodies. Electrical conductivity and the distance to the nearest house were both significant inverse predictors of larval abundance in natural water bodies. The density of larvae in fishponds raised with increasing border vegetation. Fishponds owned by different farmers varied in the extent of anopheline larval infestation but ponds owned by the same individual had similar infestation patterns over time. Commercial fishponds were 1.7-times more infested with anopheline larvae compared to fishponds for family use.ConclusionsThese results suggest that fishponds are important breeding sites for anopheline larvae, and that adequate management activities, such as removal of border vegetation could reduce the abundance of mosquito larvae, most importantly Anopheles darlingi.

Freshwater ice as habitat: partitioning of phytoplankton and bacteria between ice and water in central European reservoirs.

Abundant phytoplankton and bacteria were identified by high-throughput 16S rRNA tag Illumina sequencing of samples from water and ice phases collected during winter at commercial fish ponds and a sand pit lake within the UNESCO Třeboň Basin Biosphere Reserve, Czech Republic. Bacterial reads were dominated by Proteobacteria and Bacteroidetes. Despite dominance by members of just two phyla, UniFrac principal coordinates analysis of the bacterial community separated the water community of Klec fish pond, as well as the ice-associated community of Klec-Sand Pit from other samples. Both phytoplankton and cyanobacteria were represented with hundreds of sequence reads per sample, a finding corroborated by microscopy. In particular, ice from Klec-Sand Pit contained high contributions from photoautotrophs accounting for 25% of total reads with reads dominated by single operational taxonomic units (OTUs) of the cyanobacterium Planktothrix sp. and two filamentous diatoms. Dominant OTUs recovered from ice were largely absent (< 0.01%) from underlying water suggestive of low floristic similarity of phytoplankton partitioned between these phases. Photosynthetic characterization of phototrophs resident in water and ice analysed by variable chlorophyll a fluorescence showed that communities from both phases were photosynthetically active, thus supporting ice as viable habitat for phytoplankton in freshwater lakes and reservoirs.

New prenylated aeruginosin, microphycin, anabaenopeptin and micropeptin analogues from a Microcystis bloom material collected in Kibbutz Kfar Blum, Israel.

Thirteen new and eighteen known natural products were isolated from a bloom material of an assembly of various Microcystis spp. collected in November, 2008, from a commercial fishpond near Kibbutz Kfar Blum, the Jordan Valley, Israel. The new natural products included the prenylated aeruginosin KB676 (1), microphycin KB921 (2), anabaenopeptins KB906 (3) and KB899 (4) and micropeptins KB928 (5), KB956 (6), KB970A (7), KB970B (8), KB984 (9), KB970C (10), KB1048 (11), KB992 (12) and KB1046 (13). Their structures were elucidated primarily by interpretation of their 1D and 2D nuclear magnetic resonance spectra and high-resolution mass spectrometry. Marfey’s and chiral-phase high performance liquid chromatography methods were used to determine the absolute configurations of their chiral centers. Aeruginosin KB676 (1) contains the rare (2S,3aS,6S,7aS)-Choi and is the first prenylated aeruginosin derivative described in the literature. Compounds 1 and 5–11 inhibited trypsin with sub-μM IC50s, while Compounds 11–13 inhibited chymotrypsin with sub-μM IC50s. The structures and biological activities of the new natural products and our procedures of dereplication are described.

Environmental mercury concentrations in cultured low-trophic-level fish using food waste-based diets.

In this study, different types of food wastes were used as the major source of protein to replace the fish meal in fish feeds to produce quality fish (polyculture of different freshwater fish). During October 2011-April 2012, the concentrations of Hg in water, suspended particulate matter, and sediment of the three experimental fish ponds located in Sha Tau Kok Organic Farm were monitored, and the results were similar to or lower than those detected in commercial fish ponds around the Pearl River Delta (PRD) region (by comparing data of previous and present studies). Health risk assessments indicated that human consumption of grass carp (Ctenopharyngodon idellus), a herbivore which fed food waste feed pellets would be safer than other fish species: mud carp (Cirrhina molitorella), bighead carp (Hypophthalmichthys nobilis), and largemouth bass (Lepomis macrochirus). Due to the lower species diversity and substantially shorter food chains of the polyculture system consisting of only three fish species, the extent of Hg biomagnification was significantly lower than other polyculture ponds around PRD. Furthermore, the use of food waste instead of fish meal (mainly consisted of contaminated trash fish) further reduced the mercury accumulation in the cultured fish.

A new method for estimating visitation rates of cryptic animals via repeated surveys of indirect signs

Summary Visitation rate is a measure of the frequency with which animals visit specific locations of interest. This information is crucial for various problems in the conservation and management of animal species, e.g. to determine the risk wildlife poses to human managed resources or the predation risks of nests. An important assessment tool, especially for cryptic animals, is to count indirect signs of presence, such as tracks or faeces. Here we propose a maximum likelihood‐based method that uses information on the age of tracks or signs, and we show that existing visitation rate/probability estimators are special cases of this more general approach. Using simulated data, we compared the performance of the new visitation rate estimator to three other estimators, including the most commonly used estimator. These estimators make use of either fresh, aged or total signs, whereas our approach uses information simultaneously on both fresh and aged signs. The new estimator is, on average, in excess of three times more accurate than the next best estimator. Moreover, the new approach is very flexible and can be applied for sampling regimens with irregular time intervals between sampling. We demonstrate the application of the method to field data by estimating the visitation rate of Eurasian otters (Lutra lutra) to a commercial fish pond. To facilitate the use of this method, we provide an easy‐to‐use Excel workbook and give recommendations on the most efficient sampling regimens. Synthesis and applications. Visitation rate is an important quantity that can be estimated by repetitive sampling of indirect signs. We demonstrate the advantage of incorporating information explicitly on the age of signs over existing approaches. The new estimator can be applied to any species for which it is possible to discriminate between aged and new signs or tracks, and should be widely applicable in ecology and conservation biology.