A combination of selected indices for assessing the environmental impact of marine fish farms using long term metadata analysis

Several biological indexes can be used to assess environmental impacts of aquaculture in the aquatic ecosystem. Some biological indices are used within environmental legislative and policy frameworks which aim to monitor the impact of marine aquaculture and regulate the operation of fish farms. In Scotland, the impact of fish farms is assessed according to benthic ecosystem status compared with modeled organic loading. The purpose of this paper is to evaluate the benefits of using an optimal combination of a minimal number of selected benthic and aquatic parameters which can provide accurate and reliable information about the benthic status around the fish farm sites in Scotland. The data analyzed in this paper were obtained from the Institute of Aquaculture (IoA), of University of Stirling, and were collected from various fish farm sites across Scotland over several years. Macrofaunal and physico-chemical parameters included in the analysis were: Median Particle Size Analysis (MPSA); total sediment Carbon (C% by dw); total sediment Nitrogen (N% by dw) and Redox Potential (Eh). In this analysis a number of diversity and trophic level based indices were also used - including the Shannon Index (H'), the Infaunal Trophic Index (ITI) and the Azti's Marine Biotic Index (AMBI) - to asses the biotic status of the sites. Univariate and multivariate analysis of the data indicated that a combination of Abundance (N), H' and AMBI as biological indexes for describing the status of the ecological level along with the carbon percentage and redox potential appeared to be the give the best representation of change. This combination is even more accurate over a series of sampling stations and time points, rather than for a single site only, offering a convenient method for assessing the risk of aquaculture pollution of biotopes bellow or adjacent to floating marine fish farm cages

A model for optimization of the productivity and bioremediation efficiency of marine integrated multitrophic aquaculture

Integrated multitrophic aquaculture (IMTA) has been proposed as a solution to nutrient enrichment generated by intensive fish mariculture. In order to evaluate the potential of IMTA as a nutrient bioremediation method it is essential to know the ratio of fed to extractive organisms required for the removal of a given proportion of the waste nutrients. This ratio depends on the species that compose the IMTA system, on the environmental conditions and on production practices at a target site. Due to the complexity of IMTA the development of a model is essential for designing efficient IMTA systems. In this study, a generic nutrient flux model for IMTA was developed and used to assess the potential of IMTA as a method for nutrient bioremediation. A baseline simulation consisting of three growth models for Atlantic salmon Salmo salar, the sea urchin Paracentrotus lividus and for the macroalgae Ulva sp. is described. The three growth models interact with each other and with their surrounding environment and they are all linked via processes that affect the release and assimilation of particulate organic nitrogen (PON) and dissolved inorganic nitrogen (DIN). The model forcing functions are environmental parameters with temporal variations that enables investigation of the understanding of interactions among IMTA components and of the effect of environmental parameters. The baseline simulation has been developed for marine species in a virtually closed system in which hydrodynamic influences on the system are not considered. The model can be used as a predictive tool for comparing the nitrogen bioremediation efficiency of IMTA systems under different environmental conditions (temperature, irradiance and ambient nutrient concentration) and production practices, for example seaweed harvesting frequency, seaweed culture depth, nitrogen content of feed and others, or of IMTA systems with varying combinations of cultured species and can be extended to open water IMTA once coupled with waste distribution models

Investigation of a novel approach for aquaculture site selection

This study investigated the potential use of two “species distribution models” (SDMs), Mahalanobis Typicality and Maxent, for aquaculture site selection. SDMs are used in ecological studies to predict the spatial distribution of species based on analysis of conditions at locations of known presence or absence. Here the input points are aquaculture sites, rather than species occurrence, thus the models evaluate the parameters at the sites and identify similar areas across the rest of the study area. This is a novel approach that avoids the need for data reclassification and weighting which can be a source of conflict and uncertainty within the commonly used multi-criteria evaluation (MCE) technique. Using pangasius culture in the Mekong Delta, Vietnam, as a case study, Mahalanobis Typicality and Maxent SDMs were evaluated against two models developed using the MCE approach. Mahalanobis Typicality and Maxent assess suitability based on similarity to existing farms, while the MCE approach assesses suitability using optimal values for culture. Mahalanobis Typicality considers the variables to have equal importance whereas Maxent analyses the variables to determine those which influence the distribution of the input data. All of the models indicate there are suitable areas for culture along the two main channels of the Mekong River which are currently used to farm pangasius and also inland in the north and east of the study area. The results show the Mahalanobis Typicality model had more high scoring areas and greater overall similarity than Maxent to the MCE outputs, suggesting, for this case study, it was the most appropriate SDM for aquaculture site selection. With suitable input data, a combined SDM and MCE model would overcome limitations of the individual approaches, allowing more robust planning and management decisions for aquaculture, other stakeholders and the environment

Qualitative assessment of initial biofouling on fish nets used in marine cage aquaculture

A short communication which assesses the process of initial development of biofilms on nets used for fish culture in marine systems. Settlement follows a pattern of succession through conditioning, bacteria and diatoms with associated Extracellular Polymeric Substance (EPS) and other microscopic algae and fauna. Initial settlement appears to accelerate further settlement

Modelling seasonal nutrient inputs from non-point sources across large catchments of importance to aquaculture

Accumulation of nutrients in aquatic systems can have negative impacts on water quality, which can then affect the performance and impact of an aquaculture system. Non-point sources (NPS) and runoff from different land use practices are a major contributor of nutrients to the aquatic environment. However, NPS loading is difficult to identify, and monitoring schemes are often insufficient, particularly across large areas. Aquaculture production areas often extend across large catchments, basins and deltas and knowledge of where there could potentially be higher nutrient loads in the environment would be advantageous to inform strategic site selection and management decisions. This study developed seasonal models within a Geographic Information system (GIS) that can be applied to large catchments of importance to aquaculture to identify areas at risk of nutrient loading from NPS which should be prioritized by monitoring schemes. The models were applied to case study areas in Bangladesh, China, Thailand and Vietnam. The results of the individual models reveal changes in the spatial distribution of priority areas depending on the nutrient (nitrogen or phosphorus) and season. The modelling approach presented here has the advantage that it can be applied to large areas without the need for complex data sets. The model and outputs can also be used to assess impacts of land use and land use change on aquaculture, determine site suitability, establish zones, inform carrying capacity studies and identify potential production and disease risks

Use of physical habitat structure to assess stream suitability for brown trout : a case study of three upland Scottish streams

In 2000 the European Union introduced the Water Framework Directive, new legislation that regulates the use of surface waters within the European Community. The goal of this legislation is to protect, enhance and restore all surface waters within the Community to Good Surface Water Status. Good-Status is described as having low levels of anthropogenic distortion in its hydro-morphological and physiochemical components as well as possessing biota that would normally be associated with the type-specific aquatic ecosystem. The assessment of ecosystem status is to be defined by comparisons with intact representative reference sites, by using modelling techniques that define reference conditions, a combination of the two, or expert judgement. As undisturbed aquatic ecosystems are rare or non-existent in Europe the base-line data will have to be defined using the latter methodologies. The aim of this project is to help define reference conditions for lotic systems in Europe based on the physical instream habitat parameters of a resident species. Brown trout (Salmo trutta), a ubiquitous and well studies species endemic to Europe, was used as the target organism to develop the assessment protocol. The project focused on the requirements this species has of aspects of its physical habitat; specifically, its usage of depth, velocity, and substrate. An extensive survey of the scientific literature was used to define the requirements trout has for the three physical parameters at four life stages. These are the spawning, nursery, juvenile and adult-resident life stages. These requirements were expressed as tolerance profiles, which defined suitable, usable and not-suitable habitat. The methodology was demonstrated by evaluating the physical habitat available at six reaches in three small streams, March, Burnhouse and Bin Burns, which drain into the Carron Valley Reservoir in central Scotland. From the perspective of water depth, these streams seem best suited as nursery areas, are less well suited as juvenile habitat, and do not appear to be well matched for adult residents. The assessment of both velocity and substrate indicated that the portion of the study reaches available for use by resident brown trout increased with trout size. The assessment of all three physical habitat parameters at all study reaches found variable portions of the streams suitable for use by spawning trout. When the habitat variables are integrated all stream segments streams seem best suited as nursery and spawning areas. To a lesser extent juvenile trout can use these burns and very little habitat is available for use by adult resident trout. The tolerance profiles that were created in this study are standardized assessment criteria that when compared with stream survey data can produce an appraisal of habitat availability in any fluvial freshwater system that supports populations of brown trout (Salmo trutta). The assessment method can be combined to produce an integrated habitat assessment, using both an index and by the calculation of Froude number, which is a more realistic approach than the assessment of individual habitat parameters as salmonids choose their microhabitat based on multiple factors. This approach allows an investigator to determine the amount and relative portion of useable habitat and to determine the quality of that habitat. Finally, by examining the physical habitat variable that most strongly correlates with the final integrated habitat distribution the individual habitat parameter that is most important to the distribution of physical habitat at a site can be determined. While this technique would certainly benefit from further development it does show potential to aid in physical habitat assessment of trout streams.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Cage aquaculture in Lake Volta, Ghana. Guidelines for a sustainable future

This book describes the approach, work undertaken and key outcomes of a three-year project which commenced in December 2012. The project was based on collaboration between the Institute of Aquaculture, University of Stirling, UK, and the CSIR Water Research Institute, Accra, Ghana. It was funded by the Leverhulme Foundation through a Royal Society Africa Grant.  Our key objective was to build capacity in environmental monitoring and assessment in partner organisations and, from the work carried out, to formulate a plan for improved and sustainable cage aquaculture on Lake Volta, so contributing to the developing industry and assuring regional food security

Selective Pressure of Antibiotic Pollution on Bacteria of Importance to Public Health

Background: Many bacteria of clinical importance survive and may grow in different environments. Antibiotic pollution may exert on them a selective pressure leading to an increase in the prevalence of resistance. Objectives: In this study we sought to determine whether environmental concentrations of antibiotics and concentrations representing action limits used in environmental risk assessment may exert a selective pressure on clinically relevant bacteria in the environment. Methods: We used bacterial inhibition as an assessment end point to link antibiotic selective pressures to the prevalence of resistance in bacterial populations. Species sensitivity distributions were derived for three antibiotics by fitting log-logistic models to end points calculated from minimum inhibitory concentration (MIC) distributions based on worldwide data collated by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). To place bacteria represented in these distributions in a broader context, we performed a brief phylogenetic analysis. The potentially affected fraction of bacterial genera at measured environmental concentrations of antibiotics and environmental risk assessment action limits was used as a proxy for antibiotic selective pressure. Measured environmental concentrations and environmental risk assessment action limits were also directly compared to wild-type cut-off values. Results: The potentially affected fraction of bacterial genera estimated based on antibiotic concentrations measured in water environments is ≤ 7%. We estimated that measured environmental concentrations in river sediments, swine feces lagoons, liquid manure, and farmed soil inhibit wild-type populations in up to 60%, 92%, 100%, and 30% of bacterial genera, respectively. At concentrations used as action limits in environmental risk assessment, erythromycin and ciprofloxacin were estimated to inhibit wild-type populations in up to 25% and 76% of bacterial genera. Conclusions: Measured environmental concentrations of antibiotics, as well as concentrations representing environmental risk assessment action limits, are high enough to exert a selective pressure on clinically relevant bacteria that may lead to an increase in the prevalence of resistance

What does 'beyond compliance' look like for the Scottish salmon aquaculture industry?

Salmon farming has developed significantly since its inception in Scotland. It is now an established part of the rural communities in which it operates, is a key contributor to the Scottish and UK economies and has an important role in meeting the growing global demand for food. However, the Scottish salmon industry is subject to a number of regulatory, environmental and social licence challenges, amongst others, that must be overcome if it is to continue to develop and expand to meet ambitious targets for increasing production. Beyond compliance is one way in which the industry can seek to overcome such challenges. Based on qualitative data gathered from analysis of industry reports, stakeholder interviews and questionnaires, this paper i) provides an overview of challenges currently facing Scottish salmon farming, ii) presents beyond compliance measures already taking place, iii) discusses industry opportunities and challenges in terms of beyond compliance, and iv) offers suggestions for the future of beyond compliance, including incentives and ways in which it could be effectively measured

The evolution of aquaculture feed supply systems

First paragraph: As any fish farmer knows, feed is usually the most important variable production cost. A simple objective is therefore to minimize waste from uneaten food, which has the added benefit of reducing the risk of environmental degradation. However, decreasing feed level risks reducing growth rate, leadìng to a rise in other costs per unit of production. The optimum biological feeding rate is thus rarely the same as the optimum economic rate. In practice, these calculations are complicated as feed requirement and efficiency of conversion varies with changing environmental conditions including water temperature, oxygen concentration, water quality, current speed, light intensity and day length. Feed utilisation also varies with diet quality and physiological factors such as age/size, life-stage, stress level and endogenous rhythms. lt is therefore not surprising that these factors contrìbute towards an element of uncertaìnty regarding the amount of feed required, often leading to under or over feeding of stock and resultant under performance of the system