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To assess the effects of abiotic factors on Argulus japonicus occurrence in freshwater ecosystem, we sampled fish, free-swimming parasites, and submerged objects from rivers, fish farms, and ponds (reservoirs and lakes) at 27 locations in Guangdong province, China, from July, 2010, to March, 2013. Friedman's test and Spearman's correlation coefficient ( r) were used to investigate relationship between A. japonicus occurrence and abiotic factors in three aquatic systems. Correlation of monthly density, mean density, prevalence, abundance, and intensity of A. japonicus with water temperature, biochemical oxygen demand of 5 days, chemical oxygen demand, and ammonia were very significant, but negative relation with pH, dissolved oxygen, and total phosphorus components. Nevertheless, total nitrogen components showed an insignificant impact on A. japonicus incidence. In addition, water temperature and stability were two key factors controlling A. japonicus infestation. Our study revealed the capability of A. japonicus to inhabit and prevail in heavily polluted freshwater. Results demonstrate that A. japonicus has good adaptability to the environmental factors' stress but cannot be used as a biological indicator of environmental pollution. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The northern Gulf of Aqaba is an oligotrophic water body hosting valuable coral reefs. In the Gulf, phytoplankton dynamics are driven by an annual cycle of stratification and mixing. Superimposed on that fairly regular pattern was the establishment of a shallow-water fish-farm initiative that increased gradually until its activity was terminated in June 2008. Nutrient, water temperature, irradiation, phytoplankton data gathered in the area during the years 2007–2009, covering the peak of the fish-farm activity and its cessation, were analyzed by means of statistical analyses and ecological models of phytoplankton dynamics. Two datasets, one from an open water station and one next to the fish farms, were used. Results show that nutrient concentrations and, consequently, phytoplankton abundance and seasonal succession were radically altered by the pollution originating from the fish-farm in the sampling station closer to it, and also that the fish-farm might even have influenced the open water station. [ABSTRACT FROM AUTHOR]

Highlights: [•] Geochemical and foraminiferal analyses of fish farm sediments near Vrgada Island. [•] Elemental concentrations show only natural elemental variations. [•] Phosphorus concentration is elevated below the cage due to fish pellets. [•] Foraminiferal assemblages influenced by the substrate and phosphorus content. [•] Results point to negligible farming influence and stable environmental conditions. [Copyright &y& Elsevier]

Abstract: Escapes of cultured Atlantic salmon (Salmo salar L.) smolts from net pens in the sea and a growing abundance of salmon lice larvae in the vicinity of fish farms have potential environmental impacts. One strategy to reduce these risks could be to shorten the period the fish are kept in open net pens in the sea by producing fish up to 1kg on land-based farms. However, if fish of this size escape after transfer to net pens in the spring, how will they behave? Salmon smolts migrate to the open sea at this time of year, but fish previously kept under a constant photoperiod indoor may behave differently. In a simulated escape event, we compared the post-release behaviour of 0.5–0.8kg salmon, which had been tagged with acoustic transmitters and held outdoors under a natural photoperiod in net pens (n=20, NP), with fish kept in indoor tanks under continuous light (n=20, CP) during the previous winter. The NP fish migrated rapidly out of a 22km-long fjord after release in late May [0.46 body length per second (bl s−1)], while the CP fish moved more slowly (0.17 bl s−1) and also displayed a wider range of behaviour, with four individuals remained in the vicinity of fish farms in the fjord for at least three weeks. The production regime clearly influenced the dispersal rates of the escaped Atlantic salmon and will therefore have important effects on the type of interactions that take place between escaped farmed salmon and the environment. [Copyright &y& Elsevier]

Copyright of Revista de Investigaciones Veterinarias del Peru is the property of Universidad Nacional Mayor de San Marcos (UNMSM) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Members of the genus Flavobacterium are widely distributed microorganisms that can be recovered from a wide variety of environments. There has been an increase in the number of species isolated from fish or fish farm environments, some of them possibly associated with disease. Fourteen Flavobacterium-like isolates recovered from gills, surface of eggs and liver of rainbow trout were characterized by a polyphasic study that included a deep phenotypic, chemotaxonomic, genotypic and phylogenetic analysis. Comparative 16S rRNA gene analysis revealed that isolates represented three separate phylogenetic groups (A–C) within the genus Flavobacterium. Further genotypic and phenotypic data demonstrated that they represent three novel species of the genus Flavobacterium for which the names Flavobacterium collinsii, Flavobacterium branchiarum and Flavobacterium branchiicola are proposed. Most isolates of the three species were collected from gills indicating that they are probably commensal organisms that are able to colonize this tissue. However, some strains were recovered from the liver of two different trout, suggesting their ability to infect trout. [Copyright &y& Elsevier]

Salmonid aquaculture, producing nearly 3 million tons per year, has expanded across temperate seascapes around the globe in recent decades. Cage technologies used to farm salmonids are thought to have changed in both size and location in coastal environments, yet remarkably little data exists to explain these major developments. Using satellite images from Google Earth, we mapped and measured sea-cages and their positions to quantify changes between historical and current use in major production regions. While cage numbers have remained similar across the major producing nations from 2005 to 2020, cage diameters have increased by 27–87%, which has resulted in large increases in farm sizes (total surface area enclosed by cages per site) of 61% in Chile, 84% in Scotland, 212% in the Faroe Islands and 221% in Norway. Cage type has changed from predominately square cages within steel platforms to plastic, circular arrays over the past 15 years, with notable exceptions such as Chile and the Pacific coast of North America. While farms in the top producing regions in 2020 were slightly further from the coast compared to 2005, salmon farming remains an activity that occurs close to the coast with farms on average sited just a few hundred metres from the nearest land. Distance to the nearest neighbouring farm increased for Norway, Chile and the Faroe Islands, but decreased for Scotland and the Atlantic coast of North America. Changes in farm technology used and their location have environmental and production consequences, with larger farms producing more waste at an individual site, bigger cages impacting the dissolved oxygen available to fish within them, and proximity of farms to their neighbours influencing the risk of disease incidence and spread. Characterising cage technologies in use across the major farming regions may allow for management practices to be critically analysed to improve fish welfare and production and reduce farm biosecurity threats and environmental impacts. • Using satellite images, we compared sea-cage features of the salmon farming industry over time. • An average farm in 2020 has 12 cages of 32 m in width and is less than 400 m from shore. • Farm size has increased by 30–220% in the major producing regions from 2005 to 2020. • Supersizing farms has implications for fish welfare, production and farm impacts. [ABSTRACT FROM AUTHOR]

Abstract: Sustainability evaluation of mariculture is needed for policy decision-making in its development. Zhao et al. (2013) developed the method of emergy ecological footprint to evaluate an offshore small fish farm in the East China Sea. After re-examination of their method, data analysis process and results, three questions are presented (1) what is the nature of this method? (2) How much impact do the recognition and classification of input flows on the results? (3) Do their evaluated results confirm to the real situation of this farm? Further discussions are also made on several main studies about the emergy ecological footprint method. Our results imply: (1) there is a need to improve this method; (2) the input flows should be carefully processed due to their great impacts on the results; (3) the essential data and comparative analysis are needed to support this evaluation. [Copyright &y& Elsevier]

Abstract: This study investigated the bioaccumulation of microcystin and its potential mutagenic effects in cage-reared fish. For six months, three reservoirs (Acauã, Cordeiro and Camalau) in arid regions of Brazil were monitored. After five months, 10 fish (Oreochromis niloticus) were collected from each tank, and the amounts of microcystin in their muscles and viscera were analysed. Mutagenic effects were also evaluated. Species of cyanobacteria were present during all months of our study. The highest biovolume of cyanobacteria and microcystin in water occurred in the Acauã Reservoir; this was followed by Cordeiro and Camalau. All fish sampled contained microcystin, ranging from 16.01 to 37.09ngg−1 in muscle and 228.2–804.0μgg−1 in liver. We observed significant differences between the micronucleus count in experimental and control fish (p <0.05), suggesting a potential mutagenetic effect in the experimental fish. In all reservoirs, the fish microcystin level was well above the World Health Organization (WHO) tolerable daily intake, indicating a serious risk to consumers. [Copyright &y& Elsevier]

The article discusses the results of a study which investigated the pirarucu parasitofauna in the giant Amazon basin. It describes the pirarucu as the largest scaled freshwater fish species in the world which can reach three meters in length. It notes that pirarucu A. gigas has a high parasite diversity in the natural environment, including Myxozoa, Monogenoidea, and Nematoda. The importance of acquiring knowledge of the ecological relationships among parasites is also emphasized.

Abstract: Mariculture, especially cage aquaculture remains a growing, vibrant and important production sector for high protein food in coastal regions in China. A quantitative evaluation of the mariculture system is an essential step to documenting its’ sustainability. The method of emergy ecological footprint is applied to evaluate the environmental sustainability of an offshore small fish farm (Great Marine fish farm, GMFF) in the East China Sea. All input needed to support fish farming were accounted and converted into biological space, to estimate the natural capital demand for the rearing process in terms of global hectares. The emergy ecological footprint of GMFF was 1953.19ha, meaning that nearly 2000ha of ecologically productive lands were needed to support the fish framing. The largest component of emergy ecological footprint was forage (1183.64ha), which took up 60.60% of the total footprint; the second and third largest footprint components were fingerlings and fuel. In a word, emergy ecological footprint can serve as a practical and meaningful tool for comparing and monitoring the environmental impact of fish farming. The strong dependence of external contributions of exploiting the wild fish resources affects strongly the level of environmental sustainability of fish farming. [Copyright &y& Elsevier]

Abstract: Marine fish farms could cause environmental disturbances on the sediment due to uneaten food and fish faeces that impact the marine benthos. Polychaete assemblages are considered good indicators of environmental perturbations. The present study aimed to establish groups of polychaetes as potential indicators of fish farm pollution. This study was carried out in ten fish farms along the Spanish coast. Changes in polychaete assemblage were analyzed with meta-analysis and multivariate techniques. Abundance, richness and diversity showed significant decreases under fish farm conditions. Distribution patterns of polychaetes responded to combinations of physicochemical variables. The main ones are sulfide concentration, silt and clays percentage, and stable nitrogen isotope ratio. The results showed that some families are tolerant, Capitellidae, Dorvilleidae, Glyceridae, Nereididae, Oweniidae and Spionidae; while others are sensitive to fish farm pollution, Magelonidae, Maldanidae, Nephtyidae, Onuphidae, Paralacydoniidae, Paraonide, Sabellidae and also Cirratulidae in spite of being reported as a tolerant family. [Copyright &y& Elsevier]

The aim of this study was to investigate the influence of both facility location and typology of fish farm on some ecotoxicological, qualitative and reproductive variables in European sea bass Dicentrarchus labrax L. Several variables were investigated: gonado-somatic index (GSI), liver-somatic index (LSI); 7-ethoxyresorufin-O-deethylase (EROD), benzo(a)pyrene monooxygenase and acetylcholinesterase activities; glutathione (GSH), testosterone, 17β-estradiol, total lipid, phospholipid (PL) and triglyceride contents. In addition, the histological sections of gonads were examined. Results suggest that LSI, EROD activity, GSI, GSH, PL, hormone levels and gonad morphology were influenced by different facility locations and typologies of fish farm. [ABSTRACT FROM AUTHOR]

Fisheries are required to grant convenient environmental conditions for fish growth with minimum cost afford. Providing these environmental conditions should essentially correlate fish type, pond dimensions, water properties, and weather conditions to the fish growth rate, feeding and metabolism. The large uncertainty margin of such parameters relations and effects drives the farmers to have economically inefficient practices in their farms. The present work was divided into two parts. The first part introduced an interactive Microsoft Excel spreadsheets as a decision support system (DSS) for the purposes of fish farm area planning according to the different required purposes of ponds, water evaluation to insure the most suitable environment of fish growth, and mechanical aeration management. The design of this DSS took the simplicity of required input data and data output into consideration. The second part was a microcontroller based open loop control system for mechanical aeration process based on the calculations of the DSS. The aeration management part input and output data fed to the control system with a specially developed program using µC-language. This program performs the calculations of aeration requirements and energy demands based on the DSS calculations. Furthermore, the controller had the feature of working from isolated power supply or in collaboration with renewable energy system. These utilities have been created to be suitable for three fish types, which are Mullet, Tilapia, and Carp fish. These types have a wide acceptance in the aquaculture activities under warm water conditions. The data obtained from the calculations of the spreadsheet under simulated and real field conditions were compared to a reference data. The spreadsheet showed an agreement with the reference values. The control systems succeed to operate 1hp-3phase induction motor for a time that was identical to the required aeration time calculated through the DSS. It was recommended to rely on the created DSS and the control system for farm area planning, water environment evaluation, and mechanical aeration management and operation. In addition, improvements for the control system should be carried out to be a real-time system especially with water quality parameters considering system power requirements and operating costs. [ABSTRACT FROM AUTHOR]

Abstract: Trace element concentrations in sediment were investigated at four fish farms in the Eastern Mediterranean Sea. Fish farms effects were negligible beyond 25–50m from the edge of the cages. Based on elemental distribution, sediments from the farms were separated into coarse oxidized and silty reduced ones. Fish feed is richer in P, Zn and Cd than reference and impacted stations. Comparison among impacted stations and the respective reference stations shows that, in anoxic sediments, all elements had higher concentrations at the impacted stations than at reference stations while in oxic sediments, many elemental concentrations were lower at impacted stations than at reference stations. The behavior of elements and therefore their distribution is affected by changes in sediment grain size, organic content and redox regime. Elements in sediments around fish farms can be clustered into five groups according to these environmental variables. In silty and anoxic sediments, element concentrations were higher than in coarse and oxic ones. Several approaches were used to assess potential sediment toxicity (enrichment factors, geoaccumulation indices, contamination factors) as well as to assess the potential danger to aquatic life (Sediment Quality Guidelines, SQG). Cu, Zn and Fe can cause from threshold to extreme effects on aquatic life in anoxic, fine-grained sediments and As can cause threshold effects in all types of sediment around fish farms. Other elements (Cr, Pb, Mn) can also cause unwanted effects when compounded with elevated background levels. [Copyright &y& Elsevier]

Abstract: In order to examine the efficiency of co-culturing fish with the Japanese common sea cucumber Apostichopus japonicus, field cultivation experiments were conducted in Gokasho Bay, central Japan. I cultured A. japonicus juveniles below a fish cage and at a control station for 238days, monitored the wet weight, and analyzed its stable carbon and nitrogen isotopes (δ13C, δ15N) together with potential food sources, and found that (1) juveniles cultured below fish cages exhibited high survivorship (96%) and significantly higher specific growth rate (1.9%) than those at the control site (1.2%), and (2) the juveniles had significantly reduced δ13C values (mean±SD=−19.1±0.3‰ vs. −17.5±0.4‰ at the control station), suggesting the incorporation of C3 plant material in fish feed through fish feces and settling organic matter. All sea cucumbers which were further cultured for additional 307days below fish cages grew to the marketable size (range and mean wet weight=142–181g, 160g, n =9). In order to evaluate the effect of density on growth, 6 culture vessels, in which 1, 5, 10, 15, 20 and 25 juveniles of A. japonicus were stocked, were maintained below the fish cage over 118days. The results showed that the final mean weight of A. japonicus decreased from 6.68g to 0.94g as the density increased with a large variation of weight at the end of the experiment (coefficient of variation=52.1–62.2%), suggesting that there was competition between individuals for a limited food supply and there were intraspecific effects on the growth. This study shows the possibility of integrated multi-trophic aquaculture in which A. japonicus is cultured in the water column below fish cages, because the survival and growth of the sea cucumbers were enhanced due to the ability to avoid predator interactions and adverse environmental conditions as well as nutritional feed supply from the fish cage. [Copyright &y& Elsevier]

Abstract: Aquaculture is the most accident exposed industry in Norway, after fisheries. Interviews and observations of 55 persons in twelve aquaculture companies indicate that management rely on operating workers to make all safety-decisions in the operations, for both their biological product and themselves. Still, there is no published research about aquaculture decision-making. Given the reliance in decisions on the net cages, and the industry’s accident rate, it seems important to investigate how and why safety-related decisions are made. This paper explores criteria and constraints for decision-making in sharp end operations at fish farms. Two common situations with risk of loss are described and analyzed according to relevant research: [•] Net cage damage discovered during feeding. How to manage both planned tasks and necessary modifications? [•] The well boat crew must get the fish to the harvesting plant, but the weather is bad. How to handle tasks, time pressure and unstable conditions? The findings show that decision-makers often neglect personnel safety on behalf of product safety. Even though criteria and constraints largely coincide with theory and are similar in the two example operations, the personnel safety outcome is different. In daily operations there is major risk for the operating personnel, while in the rare well boat operations the conditions best for the fish also prevent personnel harm. When dealing with a biological production process ordinary safety measures are inadequate – because when activities need to be done at the exact right time for the product to be profitable, personnel safety comes second. [Copyright &y& Elsevier]

Purpose: This study analyzes the effects of aquaculture activities in open seawater in the north-western coastal waters of the Mediterranean Sea. It is the first of its kind to be based on benthic flux data gathered in situ below fish farms for this particular area. Materials and methods: Samples were collected on four sampling campaigns over a 1-year cycle under a Sparus aurata fish farm facility where benthic fluxes were measured in situ using light and dark benthic chambers. Bottom water and sediment samples were also collected. Data were compared to those for a nearby control station. Results and discussion: Significant differences were found (ANOVA, p < 0.05) between concentrations of organic matter (OM), total phosphorus and redox potentials in sediments located under the cages and those of the control station. The consumption of dissolved oxygen (DO) by sediment and positive ammonium (NH) fluxes was stimulated by OM content, with correlations of r = −0.60 ( p < 0.01) and r = 0.70 ( p < 0.01), respectively. The OM content of sediments was found to be consistently higher under the cages than at the control station, with the highest value (1.8 ± 0.7 %) under the cages observed during the early summer; values of DO and NH fluxes were −64 ± 17 and 12.7 ± 1.0 mmol m day, respectively. PO fluxes were consistently higher in the fish farm sediments (between 0.58 and 0.98 mmol m day) than those observed at the control station. Nitrate (NO) fluxes were found to be consistently negative due to denitrification occurring in the sediments and were related to the concentration of NO in bottom waters ( r = 0.92, p < 0.01). Si fluxes were shown to be associated with water temperature ( r = 0.59, p < 0.05). Conclusions: The results imply that sediments located below cages accumulate organic matter originating from aquaculture activities, especially during summer months when this activity increases. Sediments undergo biogeochemical changes that mainly affect fluxes of DO, NH and soluble reactive phosphorus, although these do not seem to have a significant impact on the quality of the water column due to the hydrodynamic characteristics of the area. [ABSTRACT FROM AUTHOR]

The increasing ecological significance of Planctomycetes and the still limited knowledge of this group prompted us to obtain cultured isolates from the sediment of a treatment water recycling tank of a marine fish farm. Presence of strains from this group was assessed in the sediments and water column of the tank. Eleven isolates were obtained from the sediment sample by exploiting Planctomycetes natural resistance to several antibiotics and their capacity to degrade organic matter. Based on morphological characteristics and resistance to antibiotics, Planctomycetes were identified. Their phylogenetic affiliation was confirmed by the sequence analysis of the 16S rRNA gene that revealed the presence of a group of 6 isolates closely related to Rhodopirellula baltica and a cluster of 5 isolates with 97.7-97.9 % of similarity to this species, which probably are a different species of Rhodopirellula. ERIC-PCR profiles showed a higher discrimination within the two groups and allowed the identification of nine different genotypes within the isolated strains. This work corroborates the association of Rhodopirellula spp. with fish farm environments. [ABSTRACT FROM AUTHOR]

Abstract: Sediment biogeochemical processes were measured on a transect of 4 stations FF 20W, 40W and 80W (number is metres from the fish farm, FF, to the west) at the Ardag gilthead seabream Sparus aurata farm in the Gulf of Aqaba, a highly oligotrophic system renowned for its clear water and diverse corals. At each station samples were taken for analysis of macrofaunal community and benthic oxygen demand, together with depth profiles of CHN, porosity, chlorophyll a and fatty acids. The macrobenthos was dominated by the small marine snail Nassarius sinusigerus. In contrast to many fish farms in temperate waters, a large abundance of small, opportunist worms was not observed near the fish farm although sulphide oxidising bacteria Beggiatoa spp. were observed. Oxygen demands (108–154mmolm−2 d−1) near the farm were lower than those observed elsewhere despite the high water temperature (~26°C). Bioturbation rates derived from chlorophyll profiles were low (0.013–0.069cm2 d−1) compared to results from a farm in Scotland as a consequence of the much lower infaunal abundance. Porosity, organic carbon and carbon/nitrogen ratio profiles showed clear discrimination between the stations near the cages (FF and 20W) and those more distant. A Multi-Dimensional Scaling plot of 31 sediment fatty acid concentrations from each of the 4 stations (averaged to 4cm sediment depth) shows a trend in fatty acid composition that allows good discrimination between 80W, 40W and the two stations near the farm, which overlap. An increase in the proportion of bacterial fatty acids with distance from the farm indicates a change from profiles dominated by farm wastes (with a high proportion of fish feed derived mono-unsaturated fatty acids) near the farm to background conditions where the profiles are dominated by benthic biomass. The data presented are discussed by contrasting these with earlier studies in mesotrophic systems. The results indicate that the Pearson–Rosenberg paradigm of benthic succession may be altered owing to the dominance of the benthos by N. sinusigerus and low animal abundance and so benthic indicators of impact would have to be tailored for the characteristics of this environment. Sediment water content, organic carbon content, C/N ratios and fatty acids all showed trends with distance from the farm and could be considered as indicators, as could the density of N. sinusigerus and the presence of Beggiatoa sp. mats. [Copyright &y& Elsevier]

Abstract: The aim of this research was to explore the possibility of a successful and balanced integration of fish farming installations into an ecosystem dominated by Posidonia oceanica (L.) Delile species. We selected light, temperature, seabed topography, sediment characteristics, meadow density, bottom coverage, maximum leaf length and lower depth limit as principle components in assessing the influence of the fish farm. All P. oceanica descriptors showed significant correlation with light deprivation effect while sediment organic matter content revealed slightly higher values than normal, increasing with distance from the cages. The results point to a conclusion that in such lightly nutrient enriched ecosystems, the seagrass growth and distribution are principally controlled by the shadow that cages cast on the seabed below, and that when carefully planned, fish farms do not necessarily degrade the health status of the surrounding area, but in fact facilitate a transition into a secondary stable state. [Copyright &y& Elsevier]

Introduction and purpose: Studies examining the environmental impact of marine aquaculture have increased significantly in number during the last few decades. The present paper investigates a region of rapid growth in intensive aquaculture and its influence on the local marine ecosystem. Discussion: This study was undertaken with the specific aim of assessing the effect of fish farming on marine sediment at a farm near the island of Vrgada in the Central Adriatic. Data obtained regarding major (Si, Al, K, Na, Fe, Ca, Mg), minor (Mn, P, Ti) and trace (As, Au, Ba, Cd, Co, Cr, Cs, Cu, Ga, Hf, Hg, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Se, Sr, Ta, Th, Tl, U, V, Y, Zn, Zr) elements were used to estimate the spatial and temporal distribution of metals in the sediment and their possible relationship with local aquacultural activity. Results: Although the measured concentrations of heavy metals in sediment below fish cages were notably different and potentially a result of farming activity, the values were generally lower than background concentrations observed in the Central Adriatic. In contrast, concentrations of heavy metals at a reference site unaffected by aquaculture varied from lower levels to values even higher than those observed below the high-production cages. Furthermore, calculated environmental index values indicate that the sediment below the farm is either uncontaminated or suffers from only low levels of contamination. Conclusion: Such results suggest that the effect of observed fish farm activity on the local marine ecosystem is practically negligible. [ABSTRACT FROM AUTHOR]

Two rainbow trout Oncorhynchus mykiss fish farms were repeatedly sampled in order to observe the variability of ethoxyresorufin- O-deethylase (EROD) activity and of related genes in the liver. Fish coming from fish farm A exhibited EROD levels that could be considered as basal according to the scientific literature, however, EROD activity in fish coming from fish farm B was significantly increased. This was accompanied by augmented aryl hydrocarbon receptor ( ahr) and cytochrome P4501A ( cyp1A) messenger RNA expression and reduced oestrogen receptor ( er) and vitellogenin ( vtg) transcription. Only sediment extracts from the entry channel of fish farm B induced EROD activity in O. mykiss cultured cells, however, this induction could not be explained by the levels of polyaromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) measured in the sediments. The results of this study point out that O. mykiss cultured in fish farms could be used as sentinels for indication of pollution. In this particular work, however, no conclusive evidence has been found for a relationship between the presence of PAHs and PCBs and the observed EROD induction. [ABSTRACT FROM AUTHOR]

Abstract: The paper deals with the dynamical behavior of fish and mussel population in a fish farm where external food is supplied. The ecosystem of the fish farm is represented by a set of nonlinear differential equations involving nutrient (food), fish and mussel. We have listed some results already obtained. We have analyzed for the direction of Hopf-bifurcation, stability of the Hopf-bifurcating periodic orbits, and the period of the periodic orbits by using Poincare’ normal form and center manifold theory. We have performed numerical simulation to support the analytical results. [Copyright &y& Elsevier]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bacterial infection among the most common cultured mudfish Clarias gariepinus in Africa, has become a cause of concern, because it constitutes the largest economic loss in fish farms. In order to provide useful biological data of the pathogens for good management practices, samples were collected monthly between January 2008 and December 2009 in three monoculture nursery ponds, located in three different positions: upriver (A, grassland), mid-river (B, mixed forest and grassland) and downriver (C, rainforest) along 200km length of Cross River floodplains, Nigeria. A total of 720 fingerlings between 15.1 and 20.7g were analyzed to determine the degree of infection. The bacterial pathogens were taken from their external surfaces, and were isolated and identified by standard methods. The caudal fins of fingerlings from pond A had the highest bacterial load (5.8x10³cfu/g), while the least counts (1.2x103cfu/g) were identified on the head of fish from pond C, with Flexibacter columnaris as the major etiological agent. Pseudomonas fluorescens, Aeromonas hydrophila, Escherichia coli, Staphylococcus aureus and Micrococcus luteus were identified as co-isolates with P. fluorescens as dominant (0.7x10²cfu/mL) co-isolates in pond water. Clinical signs of five white spots with red periphery appeared on the external surface of infected fish. All the fish sampled, died after 4 to 9 days. There was no significant difference in the bacterial counts between different ponds, but the difference between fish organs/parts examined was significant. Fish from these ponds are therefore potentially dangerous to consumers and highly devalued, with the economic impact to producers. Preventive methods to avoid these infections are recommended. Rev. Biol. Trop. 59 (2): 751-759. Epub 2011 June 01. [ABSTRACT FROM AUTHOR]

Seaward migration of immature salmonids (smolts) may be associated with severe mortality in anthropogenically altered channels. Few studies however, have identified distinct behaviours that lead to exposure to adverse habitats or even unsuccessful migration. This study used high resolution telemetry to map migration routes of Atlantic salmon (Salmo salar) smolts approaching a water withdrawal zone associated with an aquaculture facility in a lowland river. Individual smolts were tagged with an acoustic transmitter and released upstream of the water withdrawal zone. A trap was installed downstream of the water withdrawal zone. The trap captured all smolts that passed the water withdrawal zone. The tracking results confirmed previous studies on Pacific salmon showing that Atlantic salmon smolts may perform milling behaviours (i.e. upstream excursions and circular swimming behaviour) in anthropogenically altered channels. Non-milling and milling smolts were compared. Smolts performing milling behaviours covered a larger area (m2) and experienced an increased probability of entering the water withdrawal zone, considered an adverse habitat. Finally, smolts were identified as either passing (67%) or non-passing (33%) the water withdrawal zone based on the recapture data from the trap. In total, 20% of the non-passing smolts entered the aquaculture facility. Several behavioural traits differed between the remaining (80%) non-passing smolts and the passing smolts. In particular, time spent near the water withdrawal zone correlated negatively with the probability of passage. These links between individual behaviours and exposure to adverse habitats and passage probability may be applied to improve management of salmonid populations. [ABSTRACT FROM PUBLISHER]

Extensive grazing systems in the tropics have large greenhouse gas (GHG) emissions. Here an integrated cropping, livestock farming and saline pond aquaculture system is described which also reduces GHG emissions in tropical farming. The system was developed in the 1980s in the central Philippines and is re-evaluated in terms of its potential to reduce emissions from livestock production, particularly in wet and wet-dry tropical regions. The estimated cumulative annual GHG emission savings amount to 12.9 tonne CO2-e per head of cattle exiting the integrated feedlot system after 300 days. Use of silage from crop by-products and implementation of a feed-lot programme enabled immediate and significant reductions of GHG emissions over extensive cattle grazing. Integration with a saline animal waste processing pond allowed production of natural feed products, cyanobacteria algal mat for use in aquaculture, as crop fertiliser and soil amendment or in the silage manufacture process. Fish production from ponds receiving the harvested algal mat resulted in an annual average of 3300 kg/ha compared to an average 700 kg/ha in inorganic fertilised ponds. The unitised ratios for the integrated system were respectively: 1 ha sugarcane: 4 head of cattle: 0.13 ha saline waste processing pond. Stoichiometrically, bio-processing of waste material in saline ponds provides a novel solution to GHG emissions from feedlots. It uses a multi-step process dominated by cyanobacteria mats in which all the captured liquid and solid waste is passed through fermentation and a mixed aerobic and anaerobic photosynthesis/photosynthesis and mixed aerobic/anaerobic sulphate reduction pathway to use organic wastes and also reduce GHG emissions. Sulphate is reduced and sequestered as iron sulphide eliminating the potential for harmful sulphide emissions. Calcium carbonate precipitation in the cyanobacteria mats results in significant sequestration of carbon. The process produces organic feed matter with a three-fold increase in nitrogen levels arising from nitrogen fixation in the treatment pond. [ABSTRACT FROM AUTHOR]

An important consideration in the design of fish farms is the fate of the resultant particulate wastes. Consequently, this study is aimed at investigating the validity of an existing near-field regulatory model that assesses the fate of particulate wastes arising from fish farms. The results from the near-field regulatory model have been compared with those from a far-field model to assess the implications of the near-field model focusing on a 1 km-by-1 km area around the fish farm and ignoring any cumulative impacts of other fish farms in the area. The study has been undertaken at a site located on the west coast of Scotland encompassing Loch Shuna and Loch Melfort, which contain eight fish farms. The far-field dispersion modelling was undertaken using a layered three-dimensional tidal model with a coupled dispersion module. This study has demonstrated a number of benefits through using a far-field model to simulate particulate waste dispersion resulting from fish farms as opposed to using a near-field model. The far-field model accounts for the spatial variability in tidal currents, which can be important in coastal areas; it also allows the impacts of multiple fish farms operating in combination to be assessed over a larger area. In addition, it was found that compared with the far-field modelling, the near-field modelling has the potential to underestimate the benthic impacts of fish farms. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to identify work-related injuries and safety-hazards that happened on trout farms in Kentucky and North Carolina. An interview instrument was used to gather information on injuries, near-injury events and occupational hazards that led from work-related activities. Trout farmers reported occupational hazards such as lifting strains, slippery surfaces on hauling trucks, falls from raceway walls and walkways and falling live tank lids.

Abstract: In order to examine the efficiency of Ulva spp. (Chlorophyta) as a bioindicator and biofilter for dissolved inorganic nitrogen discharged from coastal fish farms, field surveys and field cultivation experiments were conducted in Gokasho Bay, central Japan. Naturally occurring green algae Ulva spp. were collected in and around a fish farm in February, May and July, and their δ15N and tissue N contents were analyzed. Values of these parameters obtained in May and July decreased with the distance from the fish cages, suggesting that Ulva spp. occurring in close vicinity to the fish farm assimilated the fish-excreted N. To evaluate this uptake, we cultured round cut pieces of thalli of Ulva ohnoi in transparent chambers beside a fish cage and at a control station for 2weeks in May, July and September. The specific growth rate and N fixation rate of the thalli cultivated beside the fish cage showed 12.8–23.6% and 4.2–13.9mg N g DW−1 day−1, respectively, which were significantly higher than those at the control station and found to be among the highest levels known for seaweed biofilters. The high growth rates during the warm season and easy cultivation indicate the suitability of Ulva ohnoi as a biofilter. [ABSTRACT FROM AUTHOR]

Analysis of turnover involves the causal relationships between different factors (quantity, quality and structure) and changes in economic and financial phenomenon. Such a study is required arguments for a set of management measures geared towards improving work farms analyzed. The evolution over time in turnover was based on known statistical models. The period considered in the study farm is 2007-2008, and turnover analysis refers to the business of delivering fresh and frozen fish. Following the study found that modification of fish production during the two years the level of the average price of delivery and, ultimately, turnover of the holding. Thus in 2007, fresh fish represented 56% of the total quantity of fish delivered, in 2008 the share of fresh fish delivered was only 45.5% of the total production of fish delivered. This change in structure has helped to increase overall turnover resulting from the fish market in the year 2008 consisted of turnover from the sales of fresh fish 43.7%, 56.3% difference is that of fish delivered frozen. [ABSTRACT FROM AUTHOR]