Dissertations / Theses on the topic 'Integrated Multi-Trophic Aquaculture (IMTA)'

Ett stagnerat globalt fiske har lett till en snabb utökning av vattenbruket för att tillgodose den globala marknaden. Traditionellt vattenbruk har i västvärlden kännetecknats av monospecifika odlingar, ofta med mycket grav påverkan på sin omnejd. Ett återupptäckt alternativ till denna i längden ohållbara tappning av vattenbruk har därför växt fram. Integrerad multi-trofiskt vattenbruk (IMTA) är en teknik som, genom att odla organismer från flera trofiska nivåer tillsammans, kan minska utsläppen och öka produktiviteten hos en odling. En växande global befolkningen kommer dock leda till ökande konflikter mellan kustnära vattenbruk och intressenter såsom industrier, myndigheter och privatpersoner. Då vattenbruket fortsätter att växa skulle en lösning på dessa konflikter vara att rikta dess expansion mot det öppna havet. Frågan är då om IMTA vore effektivt utomskärs och hur det i så fall skulle kunna optimeras ur både produktions- och kostnadsperspektiv. Denna undersökning tyder på att en pelagial expansion skulle ge en positiv påverkan av de olika ekologiska, ekonomiska och infrastrukturella aspekter rörande utomskärs-IMTA. Dock kräver en sådan förflyttning omfattande förarbete i utvärdering av lämpliga lokaler. En analys av olika arter och dess egenskaper, monetära värde, tillika möjligheter att optimera systemet visar på att utomskärs IMTA är möjligt, men begränsas av ingenjörsmässiga faktorer.
The stagnated global fishing has led to a fast expansion of aquaculture to meet the increasing global demand for seafood. Traditionally aquaculture in the western world has been defined as large monospecific cultures, often with grave implications on its surrounding environment. An alternative to the conventional and unsustainable method has thus been rediscovered and developed. Integrated Multi-Trophic Aquaculture (IMTA) is a technique that, by cultivating organisms of different trophic levels together, can decrease effluents and increase the productivity of a farm. Furthermore, the growing global population will lead to increasing conflicts between coastal aquaculture and other stakeholders such as industries, governments, and private citizens. Since aquaculture continues to grow, a possible solution to such conflicts could be an offshore expansion of aquaculture. However, whether an IMTA system still would be effective in an offshore setting is unclear. This is also the case regarding the possibility to optimize an offshore IMTA system concerning productivity and investment costs.  The present article shows that a pelagic expansion of IMTA would positively affect the ecological, economical and infrastructural aspects regarding offshore IMTA compared to inshore IMTA. However, such a transposition would require comprehensive preparatory evaluations of suitable sites. An analysis of several species and their attributes, monetary value, and capability of optimizing the system indicates that offshore IMTA is possible but is limited by structural-engineering factors.

Among efforts to develop sustainable approaches towards the intensive rearing of finfish within open marine waters, is the development of integrated aquaculture techniques. Integrated Multi-Trophic Aquaculture (IMTA), has been promoted as a way to reduce unwanted environmental impacts associated with the intensive production of marine finfish within net-pens. The principle aim of this concept, is the bioremediation of nutrient discharges from fish aquaculture. This is to be achieved by integrating fish cultivation with the growing of species from lower trophic levels, which use the nutrient discharges as a food source. Many studies have been performed that investigate the ability of various species of macroalgae to remove dissolved nutrient discharges, and the ability bivalves to remove solid-bound nutrients, presented as either fish faeces, or an enhanced production of phytoplankton that may be promoted by nutrients emitted by fish-farms. IMTA has also been suggested as a means to improve overall productivity per unit of feed applied to fish, through the conversion of nutrient emissions into additional biomass, such as the tissues of macroalgae or bivalves. Within the research community which focuses upon the environmental impacts of aquaculture, there is a growing awareness that sustainable solutions to aquaculture production cannot be realised through a focus restricted to the growing-phase, and to a limited set of environmental impacts which may this activity may produce. This is because changes to a specific production phase often promote changes at phases located elsewhere along a products value chain. Life-Cycle Assessment (LCA), is a method employed for modelling the environmental impacts that may potentially be generated across the value chain of a product. It is particularly useful for identifying instances of environmental impact shifting; a term used to describe situations where efforts to reduce the contribution of a specific production phase towards one or more environmental impacts, has the effect of either displacing this contribution to another phase, or increases the contribution of production towards different environmental impacts. Despite its apparent suitability, LCA has not previously been fully applied to the environmental impact modelling of open-water IMTA systems. The work presented in the following thesis advances this research front, by using LCA to explore the potential for environmental problem shifting occurring as a consequence of replacing intensive monoculture production, with IMTA. Comprehensive datasets have been acquired from the Chilean aquaculture industry, describing the production of aquafeed and Salmo salar, as well as for the production of the Phaeophytic macroalga, Macrocystis pyrifera, and the molluscan bivalve, Mytilus chilensis. Using LCA methodology, the production of salmon feed, and the production of S.salar, M.pyrifera and M.chilensis, have been assessed for their capacity to contribute towards a variety of global-scale, environmental impacts. IMTA consisting of either S.salar and M.pyrifera, S.salar and M.chilensis, or all three of these species, and combined at ratios required for a bioremediation efficiency of 100 %, 50%, or 20 % of either nitrogen or phosphorous emission from fish, is compared to the monoculture production of S.salar. The comparison is based upon a standardised functional unit, with each species produced through IMTA, being modelled as part of the reference flow required to fulfil the functional unit. Monoculture is compared to IMTA upon the basis of nutritional function, by using a functional unit of mass-adjusted protein content, and mass-adjusted economic value. The use of economic value is based upon the ‘best-case’ assumption, that it serves as a proxy for the total nutritional function that each product offers to human society. The LCAs presented in this study have produced a number of results. Salmon ingredients derived from agricultural crops and animals account for the majority (between 71 % to 98 %) of contributions towards the impacts of compound salmon feed. In general, agricultural crops ingredients contribute more to these impacts than do agricultural animal ingredients, and account for between 31 % and 87 % of the contributions from all ingredients and inputs. In contrast, the combined supply of fish meal and fish oil from capture fisheries is responsible for between 0.13 % and 11 % of all impacts. Vegetable oil accounts for the vast majority of contributions from ingredients derived from agricultural crops. Vegetable oil is modelled as a 50 : 50 blend of sunflower oil and rapeseed, oil, but sunflower oil accounts not only for most of the contributions from vegetable oil, it is responsible for over 50 % of the contributions that all agricultural crop based ingredients contributes towards some impact categories. Replacing sunflower oil with rapeseed oil reduces the contributions of salmon feed by between 6 % and 24 % across 10 out of the 11 impact categories. When compared upon the basis of equal weight, the contributions of fish oil are between 18 % and 99 % lower than those from rapeseed oil. The production of feed is responsible for the majority of contributions (between 32 % and 86 % ) to all impacts of salmon grow-out production. The production of salmon-smolts accounts for between 3 % and 18 %. The majority (64 %) of contributions towards the eutrophication potential of salmon production are from nutrient emissions, which are the result of fish metabolism, whilst nutrients released through the production of feed, the majority of these being from the agricultural production of crop and animals, account for 32 %. Feed production is also a major contributor to the impacts of land-based smolt production, but these contributions (between 12 % and 37 % across all impact categories) are of a lower magnitude than those from the supply of feed to the grow-out phase. Inputs of salt, and inputs of both electricity produced in a diesel power generator and obtained from the national electricity network, are also notable contributors (between 5 % and 67 %, 4 % and 29 %, and 2 % 47 %, respectively) towards the impacts of smolt-production. The main contributors towards the potential impacts of kelp grow-out production (excluding eutrophication potential) are the supply of infrastructure (between 14 % and 89 %), operation of a diesel-powered motorboat for maintenance purposes (between 1 % and 89 %), and the supply ‘of seeded cartridges’ (between 9 and 49 %). The major contributors from the production of ‘seeded cartriges’ in a land-based facility are the supply of electricity from the national electricity network, the supply of fresh water, and the treatment of waste water. The impact potentials of producing seed in this facility might be reduced if the scale of operation is increased. Removal of nitrogen and phosphorous upon the harvesting of kelp is calculated based upon kelp tissue contents of these nutrients. The harvesting of 200 tonnes ha / yr-1, results in a eutrophic potential with a negative value (-376.51 kg of phosphate equivalents). The removal of such a quantity of nutrients might be beneficial if the local marine environment is at risk of hypernutrification, but when no such problem is present, the potential for undesirable consequences of nutrient sequestration should be considered. The major contributor towards the impacts of mussels is the provision of infrastructure (between 25 % and 99.5 %, excluding eutrophication potential). Infrastructure is also responsible for the majority of contributions from mussel seed production. The provision of cotton mesh bags, which are used to aid attatchment of seed to drop-ropes in the grow-out phase, account for between 37% and 99 % of the contributions from the infrastructure from the grow-out phase. This result suggest that either the impacts of mussel production can be reduced by using an alternative material with lower environmental impact potentials, or the inventory data describing the producing of cottonmesh bags requires some improvement. The outcomes of the LCAs of the different IMTA scenarios, are interesting. The results show that choice of species, and the ratios of their combination as required for the different efficiencies of bioremediation, can have a significant effect upon the comparison between IMTA and monoculture.
The study demonstrates a potential for environmental problem shifting as being a consequence of IMTA, especially when the functional unit is mass-adjusted economic value. As bioremediation efficiency increases, contributions towards eutrophication decrease. However, this reduction is achieved at the cost of increasing the contributions of IMTA towards those impact categories, such as ‘ozone layer depletion,’ for which it has a greater contribution than does monoculture. In general, it cannot be concluded from these results that open-water IMTA represents a more sustainable alternative to the monoculture production of Atlantic salmon. The sustainability of IMTA is shown to be dependent upon a variety of trade-offs, between individual environmental impacts, and between these impacts and the nutritional function that the system is capable of providing.

Mestrado em Biotecnologia - Biotecnologia Industrial e Ambiental
O consumo de macroalgas pelos seres humanos tem vindo a aumentar nos últimos anos, o que está relacionado, para além do valor nutricional que lhes é reconhecido, com os seus compostos biofuncionais benéficos para a saúde. Assim, há a necessidade de aumentar sua produção de forma sustentável, onde os sistemas de Aquacultura Multitrópica Integrado (IMTA) surgem como uma alternativa promissora à aquacultura convencional, envolvendo mais de um nível trófico. No âmbito do controlo de qualidade deste novo tipo de alimento, surge um desafio: as macroalgas são organismos que tendem a bioacumular elementos potencialmente tóxicos (PTEs). O objetivo deste estudo foi monitorar a concentração de Cd, Pb, Hg e Al na macroalga Ulva rigida cultivada na empresa ALGAplus num sistema IMTA implementado pela empresa na Ria de Aveiro e inferir de um possível impacto dos factores de produção na concentração destes elementos nas algas. Avaliaram-ase três diferentes situações que poderiam influenciar a acumulação de PTEs nas algas: densidade de cultivo, taxa de renovação da água e época do ano (sazonalidade). Foi ainda feita uma comparação entre espécies cultivadas na empresa e pertencentes a outras classes: Fucus vesiculosus e Gracilaria sp. O teor de Cd, Pb e Al na biomassa de macroalgas foi determinado por atomização com plasma associada a deteção com espectroscopia de massa (ICP-MS), após digestão com ácido e microondas. O teor de Hg foi determinado por absorção atómica após combustão da amostra em atmosfera de oxigénio. As concentrações de Pb, Cd, Hg e Al para a Ulva rigida foram 0.3-3.1, <0.05, 0.01-0.03, e 121-3178 μg/g (peso seco – DW), respetivamente. A variabilidade sazonal não foi significativa (ρ > 0.05), e as condições de cultivo apenas influenciaram estatisticamente o teor de Pb (ρ < 0.05). Todos os valores obtidos para os PTEs quantificados estão abaixo do valor limite indicado na legislação que regula a qualidade das algas para consumo humano, o que evidencia que neste sistema IMTA não ocorrem problemas de contaminação com PTEs.
Macroalgae consumption by humans has been increasing in the last years, which is related with their biofunctional compounds with health benefits. Therefore, there is the need to increase their production in a sustainable way where Integrated Multi Trophic Aquaculture (IMTA) emerges as a promising alternative to conventional aquaculture that involves more than one trophic level. Quality assurance of this new aliment is crucial and that is why this study is so important: macroalgae are known to be high bioaccumulators of potentially toxic elements. The objective of this study is to monitor the concentration of Cd, Al, Pb, and Hg in Ulva rigida during the year, assessing possible correlations with the cultive conditions and seasonality. There were evaluated three situations that could influence PTEs accumulation in macroalgae: cultivation density, water renewal rate and season. A comparison was made with other species also cultivated in the company and belonging to other classes: Fucus vesiculosus and Gracilaria sp. Cd, Hg, Pb and Al content in macroalgal biomass was determined through plasma atomization and mass spectrometry detection (ICP-MS), after acid and microwave digestion. Hg content was determined through atomic absortion after oxygen-rich combustion of the sample. Concentrations of Pb, Cd, Hg e Al in Ulva rigida ranged as it follows: 0.3-3.1, <0.05, 0.01-0.03, e 121-3178 μg/g dry weight (DW), respectively. Seasonal variability was not significant (p >0.05), and cultivation conditions were significant only for Pb (p< 0.05). All values obtained are below the limit of legislation which proves that in the IMTA system there are no relevant problems related with potential toxic elements accumulation in macroalgae

Over the last few decades, Integrated Multi-Trophic Aquaculture (IMTA) in South Africa has developed from early experimental designs to large scale, commercially operating farms. This was in response to uncertainty regarding food availability for stock (primarily kelp in the case of abalone farms) and a desire to recirculate water whilst reducing the environmental footprint of the abalone farms. The growing prevalence of IMTA as a commercially viable activity has brought about a need for an expansion of the knowledge pool regarding the physico-chemical processes at work in such systems. Of particular interest to researchers are mechanisms and dynamics of nutrient transfer between components of the system and how these could be manipulated to increase efficiency and reduce running cost of farms. This work was conducted to try and quantify some of the changes in some physical and chemical characteristics of the water stream on a large-scale IMTA farm cultivating seaweed of the genus Ulva (Ulva rigida) and the locally named perlemoen abalone (Haliotis midae) on the south west coast of South Africa (Viking Abalone Farm at Buffeljagsbaai, Western Cape, South Africa) (34.7550° S, 19.6154° E). Experiment one was a three-day experiment taking place in December of 2018, there was no particular reason for the choice of month, analyses of this nature are potentially useful on any given day of any given month as although the literature contains plenty of gaps, there is no single identifiable data gap sufficient to encourage the use of particular timeframes. The sampling regime involved single sample point testing of three modular clusters each operating a different rate of water recirculation (50%, 75% and 100%) with 50% recirculation being standard farm operation, 75% and 100% tested to gauge effect of increasing recirculation, 75% tested as a potential standard farm operation to reduce load on pumps and reduce volumes of water pumped in, 100% tested in case of emergency situation which requires farm to be isolated from the inbound water stream arriving from the immediate coastal water, ambient conditions were also tested for reference and comparison. Parameters tested were those which the farmers already tested periodically to gauge changes in water quality which may effect the abalone or seaweed, though slightly different methods were used for the testing of ammonia. On the farm the standard method is the Nesler photometric test (Lovibond photometer), whereas this research was conducted using a calibrated indophenol blue spectrophotometric technique (Modified Grasshoff, 1976). Results showed no statistically significant differences (Mood's Median Test, p>0.05) between the 50% and 75% recirculation cluster for temperature, pH, Total Ammonia Nitrogen (TAN) or Free Ammonia Nitrogen NH3 (FAN). At 100% recirculation, statistically significant differences (Mood's Median Test, p0.05) occurred for temperature. At 100% recirculation, TAN and FAN increased rapidly, though the commensurate rapid and considerable decrease in pH meant the FAN increase was not as high in magnitude as it would be at 4 a normal seawater pH of around 8.2. Abalone suffered no mortalities at 100% recirculation for three days and later reports from the farmers suggested no noticeable drop in growth rate that could be attributed to this test in the months following the experiment. From the regulatory perspective, the TAN levels breached WWF guideline maximum effluent concentrations for abalone aquaculture (600µM/l) only in the 100% recirculation cluster, and only then during three of the thirteen sampling runs. The TAN concentrations in 50% and 75% recirculation treatments were far below the WWF guideline maximum effluent concentration with maximum concentrations of 7.15 µM/l in 50% and 13.46 µM/l at 75%, the increase in maximum concentration was large but not egregious and resulted from a more pronounced build-up of ammonia as residence time of water in the cluster increases at 75% recirculation. Experiment two was an intensive 24-hour sampling run; the primary aim was to test the effectiveness of the seaweed biofilter in an Integrated Multi-Trophic Aquaculture (IMTA) farm culturing perlemoen abalone and a green macroalga. Parameters tested were temperature, pH, dissolved oxygen, salinity, TAN, nitrate and nitrite as these are relevant parameters for the farmer and the necessary equipment to test them was available. Samples were stored in a freezer for this experiment due to intensity of sampling regime, and spiked standards were prepared to check shifts in concentration of TAN, nitrate and nitrite that may have resulted from the freezing and thawing processes. Spike recoveries were good in the case of TAN (87%-98%) and nitrite (92%-96%), but random and widely dispersed in the case of nitrate. As such, nitrate and nitrite were removed from the analysis as nitrite values only really held value if taken in conjunction with nitrate values. Minimal and non-useful variation in salinity observations meant that salinity was also discounted from the analysis. Temperatures varied minimally between sampling points during the experiment, though they rose in all sampling points during daytime as would be expected. pH was higher in abalone inbound and Ulva effluent water compared to the abalone effluent water. Total ammonia nitrogen percentage removal across the seaweed biofilters ranged from 65%-85% with the mean and median at 73% and 71% respectively. Free ammonia nitrogen percentage removal across the seaweed biofilters ranged from 41%-80% with the mean and median removals at 63% and 66% respectively. A regression analysis demonstrates a strong positive linear relationship between TAN removal and TAN load to the seaweed biofilter (r2= 0.90). Principal component analysis revealed a strong negative correlation between FAN removal and pH, as pH increased across the seaweed biofilters, the level of FAN removal decreased. This suggests that the perceived benefit of increasing pH in seaweed biofilters during the day-time may have some negative repercussions.

The recent research focus on integrated multi-trophic aquaculture (IMTA) is redefining the aquaculture industry's approach to intensive aquaculture. More sustainable farm model systems that include multiple farm products with integrated trophic levels are being developed. While these systems may be economically and environmentally more sustainable, it is important to realize that integrating farm products also changes disease risk on farms. This is illustrated by examining how finfish disease risk can increase or decrease depending on the pathogen in a simple finfish / blue mussel (Mytilus edulis) IMTA system. Mussels bio-accumulate and repackage the opportunistic pathogen, Vibrio anguillarum, into infectious fecal particles increasing the potential risk of infection and creating new transmission pathways. In contrast, mussels appear to inactivate the viral pathogen, Infectious Salmon Anemia Virus (ISAV) and potentially serving a role in reducing the transmission of the virus onto and off of IMTA farms.

To understand disease risk on IMTA farms, it is no longer adequate to simply investigate how a given pathogen interacts with its host under a range of environmental conditions. Evaluating the disease risk in IMTA systems requires a better understanding of how pathogens may potentially interact with all of the components of the farm system, while recognizing new potential pathways that may be created or enhanced within and by the system its self. Through a more comprehensive understanding of these potential interactions farmers can apply a range of bio-security and best management practices to limit the risk of disease on IMTA farms. With good management IMTA farms should not increase the risk of disease, but may actually reduce the spread of pathogens in some situations.

Sea-based integrated multi-trophic aquaculture (sIMTA) was explored as an amalgam of the processes of polyculture and biofiltration, with the primary objectives of improved aquaculture production efficiency and wastes remediation. The study established a coculture of Atlantic salmon (Salmo salar, L.), Pacific oyster (Crassostrea gigas, Thunberg) and sugar kelp (Saccharina latissima, L.), in Scotland, and explored their production in relation to the background environment, historical aquaculture production modes, regulation and resource-use. The field trials demonstrated the dominance of the ambient environment in regulating trophic linkage of co-cultures. Enhanced growth of the bivalve and macroalgal components, over reference cultures, was only observable when ambient nutrients were limiting or favoured food, i.e. phytoplankton, was scarce. Localised differences within and between sealoch systems were also observed to be of importance. The complex physical processes of particulate waste dispersion and dissolved nutrient diffusion were simulated using established models and field data drivers. This process illustrated the potential benefits of designing the integrated farm to optimise trophic linkages as well as considering the final fate of wastes. The application of sIMTA was explored within the current regulatory regime, illustrating what regulatory gains (statutory and non-statutory) might be possible on account of the process and how the products of integration, as studied, are likely to meet with few regulatory food safety constraints within a UK market. The scarcity of aquaculture resources, partly through inefficient use, was explored. sIMTA is presented as a method which could possibly alleviate some of these resource-use inefficiencies when ambient environment supports, and as such sIMTA is proposed to qualify for priority resource allocations, in the context of greater socio-economic advantage.

La production de crevettes en Indonésie est en constante augmentation de part sa surface et l'intensification de ses élevages. Cette filière contribue au développement économique en milieu rural, à la sécurité alimentaire nationale, à l'emploi et au commerce extérieur. Cependant, ce développement rapide s'est accompagné d'effets écologiques et sociaux négatifs. Le développement de maladies dans les élevages ainsi que la dégradation de l'environnement côtier a conduit à l'abandon de 250 000 hectares de bassins dans le pays. Leur réhabilitation dans le cadre d'une activité durable est aujourd'hui une priorité pour le gouvernement indonésien.L'objectif de cette thèse est de développer des outils et des méthodes, basées sur de l’imagerie satellites à très haute résolution spatiale (THRS), (1) pour une meilleure gestion des sites de production et (2) pour réhabiliter les sites abandonnés. L'estuaire de la Perancak situé dans la Province de Bali, une zone de production en déclin, a été choisi comme site pilote. Ce travail a été réalisé dans le cadre du projet INDESO dont l'objectif était de fournir des outils et des méthodes pour une meilleure gestion des ressources côtières et marines en Indonésie.Le premier outil développé pour objectif de cartographier automatiquement les bassins d'élevage. A cet effet, une méthode basée sur la détection des contours a été mise en place et comparée à deux autres méthodes, la première basée sur la méthode de croissance des régions, la seconde sur une classification non supervisée (plus particulièrement la méthode Isocluster). Notre méthode a permis de détecter une forte proportion de bassins avec une meilleure précision.Le second outil avait pour objectif de distinguer les bassins actifs des bassins abandonnés. Un indicateur intégré (IPAI) basé sur quatre critères identifiés sur les images THRS que sont la présence d'eau, d'aérateur(s), de ponton(s) d'alimentation et de végétation, a été développé. Cet indicateur permet de distinguer significativement un bassin actif d'un bassin inactif. La présence de ponton est le critère qui s'est révélé être le plus discriminant.Cet indicateur a été utilisé sur l'estuaire de la Perancak pour suivre la dynamique d’abandon des bassins, liée au développement des maladies dans les élevages, entre 2001 et 2015. Deux facteurs de risque conduisant à l'abandon ont été mis en évidence : le climat et le positionnement des bassins au sein de l'estuaire. Ces résultats suggèrent qu'une approche spatiale doit être prise en compte pour la réhabilitation des bassins. Trois zones ont été définies à partir de leur résilience spatiale aux maladies. Le niveau de connectivité entre des bassins via le réseau hydrologique augmente le risque d'abandon. A noter que la présence actuelle des pathogènes (White Spot Syndrome Virus, WSSV) dans les bassins et probablement dans l'environnement génère une mémoire écologique défavorable à la réhabilitation de fermes aquacoles de crevettes.A partir de ces résultats, une première proposition de plan pour réhabiliter les bassins abandonnés a été formulée dans le cadre d'une approche écosystémique. Pour lutter contre les maladies, ce plan suggère de développer une aquaculture multi-trophique intégrée (AMTI), basée sur la diversité des espèces élevées et de leur positionnement dans la chaine trophique, à l'échelle de l'estuaire. Les méthodes et les études qui doivent être conduites pour rendre opérationnelle cette proposition sont discutées
Shrimp farming production in Indonesia has continuously increased through a large expansion of cultured areas and stocking density intensification. This activity supports rural economic development and contributes to national food security, employment and foreign exchange earnings. However, this development has generated adverse ecological and social effects. As consequences of diseases and environmental degradations, there are currently 250,000 ha of abandoned ponds. Their rehabilitation, within a sustainable aquaculture framework, is actually a high priority for the Indonesian government.The objective of the present PhD work was to develop tools and methodologies to (1) enable better management for operating sites of shrimp industry and (2) rehabilitate abandoned sites using very high-resolution satellite (VHRS) imagery. The Perancak Estuary, located in Bali Province, is the production area in decline that has been chosen as study site. This work has been carried out in the frame of the INDESO project which was assigned to develop and provide tools and methods for better management of marine and coastal resources in Indonesia.The first developed tool was an automatic classification procedure for aquaculture mapping. A method based on Edge Detection on VHRS images was proposed and compared with those generated by Region Growing segmentation and unsupervised classification Isocluster. Edge Detection method could successfully create aquaculture map in the Perancak estuary by identifying a large proportion of existing ponds, with good overall accuracy.To implement effective procedure for appropriate aquaculture ecosystem assessment and monitoring, the second tool was an Integrated Pond Activity Indicator (IPAI). It aimed to discriminate active from abandoned ponds and was developed based on four criteria using VHRS images. Those criteria were: presence of water, aerator, feeding bridge and vegetation. This indicator succeeded in detecting active pond with a good accuracy, and feeding bridge appeared to be the most discriminant criteria.This second indicator has then been applied to the Perancak estuary to highlight the abandonment dynamic due to disease between 2001 and 2015. Two risk factors that could contribute to explain dynamics of abandonment were identified: climate conditions and pond locations within the estuary, suggesting that a spatial approach should be integrated in planning processes to operationalize pond rehabilitation. Three areas were defined based on their disease resilience. Ponds connectivity through water network increased the risk of disease development. The continued presence of shrimp pathogen species in ponds and probably in the environment (i.e. White Spot Syndrome Virus, WSSV) may generate ‘ecological memories’ that prevent to the return of shrimp productive system.These results were used to establish a first proposal of rehabilitation plan using an ecological approach. At the whole ecosystem scale, the development of an integrated multi-trophic aquaculture (IMTA), based on the diversity of cultured species and their trophic status would be implemented. Methods and studies that would be conducted to operationalize sustainable pond rehabilitation are briefly discussed

Ulva as an aquaculture crop and IMTA component species has received mixed results globally; success has been achieved in South Africa and Israel, whilst in Europe the results have been poor. This project aims to determine if Ulva lactuca is a suitable candidate as an inorganic extractive species component within marine IMTA systems in British Columbia. The inorganic extractive feasibility of U. lactuca was determined with combination of real time growth and nutrient uptake experiments, alongside a SWOT analysis and literature review to reveal the possible potentialities and pitfalls. U. lactuca was cultivated in 680 litre tanks in the effluent of Wolf Eels, Anarrhichthys ocellatus in a recirculation system at the Aquatics facility at the University of Victoria. Growth experiments of wild local U. lactuca strains attained summer growth of up to 17.43% specific daily growth rate, with winter growth of up to 4.26% specific daily growth rate. U. lactuca demonstrates a preference for Ammonia-N uptake over other forms of inorganic nitrogen and a reduced nutrient uptake capacity during dark periods. Nitrate uptake capacity up to 202µm N gDW-1 day-1 was exhibited. These figures display the excellent biological potential of local Ulva lactuca strains to act as an inorganic extractive. However currently, long term maintenance of the crop proved problematic with instability with growth rates and nutrient uptake capacity. Cultivation issues in combination with poor economic outlook will restrict the feasibility of this species to specific types of IMTA system. Beneficial steps towards the deployment of U. lactuca inorganic extractive components would include: (i) the identification of suitable sterile strains or employment of “germling” spore production, (ii) the use of a rotational, light weight, cage cultivation system, (iii) being farmed in combination with a dark period nutrient removal species, such as Chondrus crispus, (iv) being farmed in conjunction with in-situ algivorous species.
Graduate
0792

Most aquaculture tenures in British Columbia (BC) are located in coastal First Nation traditional territories, making the aquaculture industry very important to First Nation communities. Marine aquaculture, in particular salmon farming, has been labeled one of the most controversial industries in BC and various groups with differing opinions have created a wide-spread media debate known as the “aquaculture controversy”. Industry, government, and (E)NGO’s are often the most visible players; First Nations, especially those without aquaculture operations directly in their territories, are often excluded or underrepresented in the conversation. In particular, remote communities from the central and north coast are significantly underrepresented. Aquaculture is predicted to expand in BC, making it crucial to know the opinions of these communities. By drawing on twelve key informant interviews conducted in situ in three central and north coast First Nation communities, as well as other literatures and discourses, this thesis explores the aquaculture controversy and perspectives towards finfish, shellfish, seaweed and Integrated Multi-Trophic Aquaculture (IMTA) systems. The thesis suggests that there is little interest in salmon aquaculture in the communities of Oweekeno, Skidegate and Massett; however there is significant interest in shellfish farming and to a lesser extent seaweed and IMTA. It also sheds light on the major issues and concerns of the current industry and potential interest areas in-line with First Nation values. In doing so, the current research contributes to the knowledge mobilization of First Nation perspectives towards coastal aquaculture in BC.
Graduate
0366
ktebbutt@uvic.ca

One advantage of Integrated Multi-Trophic Aquaculture (IMTA) is the potential for bioremediation by organic-extractive organisms. In British Columbia, a number of marine invertebrate species are being considered for use in open-water IMTA with sablefish (Anoplopoma fimbria). These include both filter-feeding bivalves (e.g. cockles, mussels, oysters, scallops) which would consume the finer suspended particulates from the finfish culture component and deposit/detrital feeders (e.g. sea cucumbers, sea urchins, prawns) which would feed on the heavier-settleable solids. The following candidate species were tested for their ability to consume sablefish faeces and uneaten sablefish feed in laboratory feeding trials: green sea urchin (Strongylocentrotus droebachiensis), basket cockle (Clinocardium nuttallii), blue mussel (Mytilus edulis), spot prawn (Pandalus platyceros), and California sea cucumber (Parastichopus californicus). Whether they can remove organic material from aquaculture wastes was tested by measuring ingestion rate or clearance rate and absorption efficiency when they were fed a diet of sablefish waste, relative to those fed a natural control diet. Egestion rates in the candidate species were quantified to estimate the potential amount of waste that may be lost from the organic-extractive component. Biophysical properties including shape, size, and settling velocity were measured in faecal pellets egested by the candidate species to provide input data for models to assess dispersal of faeces from IMTA sites. Results from the laboratory feeding trials demonstrate that all candidate species are capable of consuming wastes from sablefish aquaculture and absorbing the organic material. The relative merits and drawbacks of each candidate species are discussed with respect to the results and within the broader context of IMTA. The general conclusion is that, in order to achieve efficient removal of organic material and successful bioremediation, deposit feeders should be included in the organic-extractive component, whether alone or in conjunction with suspension feeders.
Graduate

Dissertação de mestrado em Biodiversidade e Biotecnologia Vegetal, apresentada ao Departamento Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Chondrus crispus Stackhouse, Irish moss, is a traditionally harvested seaweed of the Portuguese coast. The tetrasporophyte life phases produce lambda-type carrageenan, which has a wide application in the food industry and is increasingly promising in the pharmaceutical and cosmetic industries. Combining a carrageenophyte with promising new market niches, such as cold-water C. crispus lambda-carrageenan, may contribute to boost the economic viability of Integrated Multi-Trophic Aquaculture (IMTA) in Portugal, while converting land-based intensive fish farms into an ecological and more sustainable aquaculture. In the present study, IMTA-cultivated C. crispus had good carrageenan yields with alkaline extraction process when compared to wild harvested C. crispus from the Centre and North Portuguese coast. FTIR-ATR spectroscopy analysis of the carrageenans produced by IMTA-cultivated specimens, both in their native state and the alkaline extracted, was in conformity with results from previous studies on wild C. crispus from the Portuguese coast.

The goal of this thesis was to detail spatial and temporal organic particulate dynamics at an integrated multi-trophic aquaculture (IMTA) site on the west coast of Vancouver Island, Canada. To accomplish this goal, in-situ optical measurements of particulate scattering (bp), particulate backscattering (bbp) and the particulate backscattering ratio (bbp:bp) were collected in conjunction with discrete sampling for particulate organic carbon (POC) and chlorophyll a (chl a) concentrations. These measurements were performed over three seasons (autumn, winter and summer) at reference sites and at sites within and directly adjacent to the fish component of the IMTA system. Chapter 2 of this thesis focused on the examination of bio-optical relationships over various timescales (seasonally, daily and within-day) to describe temporal and vertical particulate variability and to assess the effectiveness of bio-optical methods for environmental monitoring. Autumn showed low bio-optical magnitudes with distinct lower cage increases possibly attributable to aquaculture derived wastes. In spring, sampling was performed over diatom bloom conditions, dominating the bio-optical measurements. During summer, an Emiliania Huxleyi bloom likely occurred, strongly enhancing bbp and bbp:bp magnitudes in the thermally stratified upper water column. Throughout these conditions, bp was predominantly influenced by chl a suggesting sensitivity to phytoplankton concentrations. While bbp was conditioned by chl a during the diatom bloom, it was also highly sensitive to the presence of inorganic and likely detrital materials. Finally, bbp:bp was sensitive to particulate compositions, showing low values (< 0.010) in diatom dominated waters and high values when refractive coccoliths were likely present. Notably, in autumn, bbp:bp was conditioned by detrital particles and along with bbp, showed post-feeding lower cage increases suggesting that these parameters could be useful candidates for particulate waste tracking during low ambient particle conditions. In chapter 3, the temporal, vertical and horizontal dispersion of the aquaculture derived particulate wastes are detailed. Autumn was the only period to show waste signals, likely due to their quick dilution into the particulate rich fields in spring/summer. During this period, post-feeding particulate waste increases were focused at the bottom of the cage with possible vertical sinking towards the seafloor. Minimal horizontal dispersion towards the scallop portion of the system was observed; however, more comprehensive sampling over differing hydrographic regimes is necessary to characterize waste dispersion. Based on our temporally limited autumn results, the most appropriate placement of uptake species for waste assimilation would be directly below the studied cage. Our results highlight the need for high spatial and temporal resolution methods for particulate monitoring within IMTA settings as discrete sampling may miss “patchy” waste dispersal streams. The bio-optical measurements performed during this study could fill this need as they can provide high resolution information on particulate concentrations and compositions not achievable solely through the use of discrete water sampling. With further research, optical instrumentation could be incorporated into IMTA systems allowing for the near real time and continuous collection of data on particulate dynamics. This knowledge could greatly aid in the design and implementation of systems optimized for waste removal by uptake species.
Graduate
0792
0768
0752
jdelbel@uvic.ca

A composição nutricional de cinco espécies de algas verdes (Rhizoclonium riparium, Ulva lactuca, Ulva prolifera, Chaetomorpha linum, Ulva intestinalis) em sistemas de aquicultura multitróficos foi estudada. Em primeiro lugar, a fucose e os polifenóis totais, como constituintes bioativos relevantes, foram analisados e as atividades antioxidantes e anti-inflamatórias foram medidas. Os efeitos da bioacessibilidade nesses aspectos também foram avaliados. Embora o teor de lipídios tenha sido muito baixo (menos de 3 g / 100 g de peso seco), houve diferenças qualitativas entre as frações lipídicas, uma vez que os perfis de ácidos graxos variaram consideravelmente entre as cinco espécies de algas marinhas. O teor de fucose também dependeu das espécies específicas. O conteúdo total de polifenóis e a atividade antioxidante apresentaram correlação significativa. U. prolifera apresentou o maior teor total de polifenóis e atividade antioxidante, enquanto que nenhuma atividade de polifenol ou antioxidante foi encontrada na fração bioaccessível. A atividade antiinflamatória foi maior nos extratos U. prolifera e C. linum com alta inibição de COX-2 (variando entre 18 e 27%) a uma concentração de 100 μg / mL. Apesar dos compostos que causam essa atividade antiinflamatória não serem tornados bioaccessíveis, a U. prolifera parece ser uma fonte potencial de substâncias bioativas, desde que sejam utilizados métodos adequados para sua extração ou desenvolvidos desenvolvendo tisanas que possam aumentar sua bioacessibilidade. Em segundo lugar, estudou-se a composição lipídica das cinco espécies de algas verdes. Em particular, o perfil geral de ácidos graxos (FA) e o perfil FA de cada classe principal de lipídeos encontrados nestas espécies de algas marinhas foram cuidadosamente analisados. Verificou-se que todas as algas tinham um perfil FA específico, cujas especificidades foram mais evidentes com o estudo do perfil FA por classe de lipídios. No entanto, entre U. lactuca e U. intestinalis, houve apenas pequenas diferenças. No entanto, foi possível identificar diferenças significativas entre o teor de ácido palmítico na classe PL de cada alga. Uma clara distinção entre os perfis de R. riparium e C. linum (Cladophorales) e os de Ulva (Ulvales) também foi determinada. Além disso, houve diferenças entre as classes de lipídios, produzindo grandes contrastes entre PLs e TAG, bem como entre MAGs e FFA. Este estudo também encontrou evidências que suportam a localização de FA específicas em posições TAG específicas. Finalmente, a composição mineral foi estudada. A bioacessibilidade elementar nessas espécies também foi investigada através da aplicação de um modelo digestivo in vitro inovador. Observou-se que R. riparium apresentou os níveis mais altos de Mn, Sr, Cd, Sn e I e que a U. lactuca apresentou as maiores concentrações de Ni e Cu. As quantidades diárias de algas verdes secas necessárias para a obtenção de ingestão dietética específica foram calculadas: 7 g de U. lactuca secas (para a reunião Cu recomendado diariamente, RDA); 173 g de U. lactuca seca (Zn RDA); 78 g de C. linum seca (Se RDA); 41 g de C. linum seca (Mo RDA); e 0,5 g de R. riparium seca (I Dietary Reference Intake, DRI). Mn e Cu tiveram os valores mais elevados de bioacessibilidade elementar, sempre acima de 50%, enquanto que sempre fui praticamente bioacessível, na faixa de 14-31%. A faixa de bioacessibilidade de R. riparium (31-100%) foi maior do que as faixas para outras espécies, particularmente a de C. linum (≤ 56%). Os resultados de bioacessibilidade implicaram maiores quantidades de algas secas para atingir a ingestão dietética: 10 g de U. lactuca seca (Cu RDA); 290 g de R. riparium seca (Zn RDA); e 2 g de R. riparium seca (I DRI). Consequentemente, R. riparium é uma fonte muito rica. Este estudo mostrou a importância de levar em consideração resultados de bioacessibilidade na estimativa de ingestão dietética.

To assess the spatial distribution of nutrient wastes around an open-water integrated fish/mollusk/kelp farm in-situ kelp bioassays were employed. Growth rates were measured over a four-month growing season and used as a proxy for relative nutrient concentrations. Seasonality and depth effects on growth rate were also assessed. Growth around the pens was 0.20 cm • day-1 higher than at the control, and reached a maximum of 1.4 cm • day-1. Optimal growth was achieved at 8 m. Growth at 8 m was significantly higher by 1.5 cm • day-1 compared to surface waters at 2 m. Early spring had the highest growth rates with a peak of 1.4 cm • day-1 recorded on June 21. This study re-iterates the fundamental benefits of IMTA and shows the potential of in-situ assay as an alternative to error-prone and costly water sampling to asses nutrient status in water.
Graduate

In integrated multi-trophic aquaculture (IMTA) production of cultured species may not align temporally. For instance, at an IMTA site in Kyuquot Sound, BC where the cultured species are Anoplopoma fimbria (sablefish), Plactopentin yesoensis (Japanese scallop) and Saccharina latissima (sugar kelp), sablefish are grown year round while the kelp culturing lasts from winter to summer. Kelp sporophytes become visible in early spring while harvest takes place in July. This indicates that at Surprise Island the time period of nutrient extraction by the kelp is limited to only a few months per year. Two potentials methods to lengthen the time in which the kelp component was on site were employed and evaluated: 1. the use of multiple kelp species with potentially differing seasonal growth strategies and; 2. outplanting kelp seed at four different times of the year. The first method involved outplanting seed of four kelp species, Saccharina latissima, Costaria costata, Alaria marginata and Saccharina groenlandica and monitoring growth parameters (blade length and yield). For the second method, a modified seed production method of Merrill and Gillingham (1991) with Luning and Dring (1973) successfully provided seed throughout the year. Seasonally out-planted seed was also monitored for growth parameters. Results were marginal for experiments and were confounded by the lack of growth rates due to infrastructure problems, grazing by naturally setting marine snails and seemingly poor environmental conditions for kelp culturing at the farm site. However, data indicated that certain species in co-culture may slightly increase the time period, and strategically entered kelp seed may do the same. In particular the co-culture of C. costaria and S. groenlandica or biannual seed outplanting in fall and spring may increase the length of growth period of kelp provided certain limitations found during this experiment are overcome (i.e. pressures of grazing). Additional potential benefits with these kelp production strategies are the diversification of final kelp products, additional kelp harvests and increased production.
Graduate

Palmaria palmata and Chondrus crispus were cultured in the lab at three levels of temperature and two of nitrate, representative of commercial Atlantic halibut farming conditions. Productivity and nitrogen removal by P. palmata were greatest at temperatures <10°C. Productivity of C. crispus was greatest at >10°C, while nitrogen removal was unaffected by temperature, 6-17°C. When cultured in various nitrate and ammonium combinations, nitrogen uptake was highest when available as ammonium. Both species took up 89-100% of ammonium in 24 hours, but only 23-37% and 55-87% of nitrate was taken up by P. palmata and C. crispus, respectively. When P. palmata was integrated with halibut recirculating aquaculture, productivity and nutrient removal were compromised during summer. During winter, <11°C, nitrogen removal by P. palmata was relatively stable at 2.3 gN m-2 d-1. For 50% nitrogen removal from halibut aquaculture during winter, a finfish: seaweed biomass of 1: 1 would be required.

Aquaculture facilities have been demonstrated to emit massive quantities of waste that incorporates in to the surrounding water column, effectively altering patterns and processes of nearby marine communities. Given that products from aquaculture is heavily relied upon to meet global fisheries demands, understanding its effects is essential to inventing less harmful practices. This research examines one such facility located in Kyuquot, British Columbia. The purpose of this thesis is to spatially and temporally measure the degree and magnitude of integrated multi-trophic aquaculture (IMTA)-derived organic waste as a potential subsidy to adjacent marine communities. Stable carbon and nitrogen isotopes analysis was applied to intended extractive organisms (sablefish Anoplopoma fimbria, Pacific scallops Patinopectin caurinus, blue mussels Mytilus edulis, sea urchin Strongylocentrotus franciscanus, sea cucumber Parastichopus californicus, kelp Saccharina latissima), epibiont biofouling species (brooding transparent tunicates Corella inflata, hairy tunicate Boltenia villosa, broadbase tunicates Cnemidocarpa finmarkiensis) as well as fish feed and sablefish faeces. Stable isotopes of blue mussels and brooding transparent tunicates sampled from both the IMTA and a reference site were compared in order to examine spatial influence of IMTA-derived waste. IMTA site sampled mussels exhibited the most enriched and least variable values among all four sample groups. Brooding transparent tunicates exhibited the most isotopic variability which demonstrates that IMTA-derived waste is not among the most important food source available. This is corroborated by the three-source mixing model results. Only sablefish isotopic signatures were measured to be more enriched than those of fish feed and fish faeces. Isotopic mixing models were employed to all IMTA samples and found that IMTA effluent signatures were proportionately higher in their diets than averaged marine particulate organic matter (POM) signatures taken from the literature. Mixing model results also showed IMTA effluent to be proportionately less than marine POM. Circular statistical results did not demonstrate particular directional change for all IMTA sampled isotopic signatures which could be due to the consistent nature of available fish feed throughout the year and/or perhaps feeding choice changes constantly. Further examination into the monthly physical properties of this region (eg. rainfall, irradiance) as well as measurements of marine POM signatures would greatly compliment these results and are recommended for future study.
Graduate

碩士
東吳大學
微生物學系
107
Although the aquaculture industry's process of intensive production can increase the yield, it is also likely to cause a deterioration of the aquaculture environment. Few of the most common effects are an increased amount of the antibacterial agents and antibiotics used, raised incidence of drug-resistant bacteria and a decrease in public health security. To better maintain the sustainability of the aquaculture, the development and use of biological agents has received increasing attention. Previous study has shown that the Integrated Multi-Trophic Aquaculture System (IMTA) is potentially feasible for rearing Chanos chanos and the effectiveness of supplementation of photosynthetic bacteria Rhodovulum sulfidophilum as an aquaculture probiotic to this system was analyzed in this thesis. We measured the physicochemical properties of the pond waters and sediments of the IMTA, analyzed the community structure of bacteria and the presence of antibiotic resistance genes and enzymes involved in the nitrogen and sulfur cycling upon supplementation of the R. sulfidophilum. The results indicate that the application of photosynthetic bacteria can stabilize the flora, increase species diversity and richness, reduce the incidence of some drug resistance genes, and also change the presence of microorganisms involved in the elemental cycle. Based on the analysis of metagenome, we further learned that there are significant differences in the types and numbers of bacterial strains that carry these nitrogen-sulfur recirculating enzymes between the two types of sediment samples. It is expected that the provision of this information will bring us closer to the goal of optimizing the aquaculture environment.

Excess nutrients in the form of uneaten food or waste from intensive, monospecies aquaculture farms can have negative effects on the surrounding natural ecosystem, causing eutrophication and benthic habitat degradation. Biomitigative techniques such as Integrated Multi-Trophic Aquaculture (IMTA) are being investigated for their ability to reduce these negative environmental impacts. IMTA is the co-culture of multiple species from complementary trophic levels, physically orientated in such a way that excess waste nutrients from the fed component are intercepted by the extractive species. For IMTA systems to become a sustainable aquaculture design alternative, it is important to ensure that infrastructure orientation and stocking densities of the extractive species maximize the amount of excess nutrients intercepted and overall system efficiency. Previous research has shown that the majority of wastes from fed finfish are made up of large organic particulates which sink rapidly to the benthos underneath or near the fish cages and which would be available to benthic deposit-feeding species. The California sea cucumber (Parastichopus californicus) is a promising extractive species for IMTA on the west coast of Canada due to its deposit-feeding behaviour and its relatively high market price. Owing to the sea cucumber’s morphology and ability to move through restricted spaces, containment can be difficult without reducing nutrient transfer and overall IMTA system efficiency (i.e. mesh sizes needed to contain small sea cucumbers may restrict flow of farm particulates to them). The overall goal of the present work is to effectively contain juvenile sea cucumbers in such a way that maximizes benthic extraction of large-particulate nutrients within an IMTA system.
Graduate

Prevention and removal of biofouling from nets and product is a huge expense in the aquaculture industry. Of the many technologies that slow the accumulation of biofouling, copper-based coatings are used most commonly as they are a relatively inexpensive and effective option. However, they can leach into the marine environment and have potentially harmful impacts on marine life. In previous studies, sea urchins have shown potential as a non-toxic alternative to control fouling. In this field study, five different stocking densities (i.e. 0, 30, 60, 90, 120 urchins net-1 or 0, 2.46, 4.91, 7.37, 9.82 urchins m-2) of green sea urchins, Strongylocentrotus droebachiensis, were randomly placed in 30 mussel predator exclusions nets (with six replicates per density treatment) in order to test the effect of urchin density on biofouling intensity and urchin/mussel growth. Mussel predator exclusion nets were chosen to house the urchins since they are necessary to protect mussels from diving ducks and sea otters on the west coast of Vancouver Island, British Columbia, Canada. The urchins provide a means of controlling biofouling as well an additional marketable crop to offset predator net expenses. After 174 days, the percent net occlusion, mussel growth, and urchin growth were quantified. Nets with urchins were significantly less fouled than those without urchins. Fouling on nets with higher stocking densities of urchins (90 and 120 urchins net-1) was significantly less than that on nets with the lowest stocking density (30 urchins net-1). Fouling was no longer significantly reduced at densities >60 urchins net-1 or 4.91 urchins m-2. While fouling was significantly reduced in the presence of urchins, it was not completely eliminated as they were only able to access the inside surface of the nets. There was no significant difference in mussel growth at the different urchin stocking densities, but urchin somatic growth and gonad growth did decline with increasing urchin stocking density. Mussels and sea urchins can be successfully co-cultured with no food inputs, but there is a trade-off between biofouling control and urchin growth.
Graduate

Atualmente reconhece-se a importância dos ecossistemas costeiros, quer a nível ecológico, quer para atividades humanas, tais como lazer ou para produção em aquacultura. A Ria Formosa é considerada uma das lagoas costeiras mais importantes da Península Ibérica onde existem sistemas de aquacultura em tanques de terra. Estes sistemas de produção são caracterizados pelos seus efluentes, ricos em matéria orgânica. Novos sistemas de produção têm sido desenvolvidos como forma de minimizar os impactos provocados por produções aquícolas, sendo que um deles é a produção em sistemas de aquacultura multi-trófica integrada que é conseguido utilizando culturas, em simultâneo, de organismos consumidores (por ex. peixes) que libertam elevadas quantidades de matéria orgânica e espécies capazes de assimilar matéria orgânica (por ex. bivalves) e inorgânica (macroalgas). As macroalgas são reconhecidas pela sua grande capacidade como depuradores biológicos. A sua presença em sistemas de produção multi-tróficos é, portanto, muito importante. As comunidades de macroinvertebrados constituem um elo intermédio nas teias tróficas e são importantes como integradoras das condições ambientais de um determinado habitat e como acumuladores de matéria orgânica pronta a ser transferida para níveis superiores. Certos grupos de invertebrados são utilizados na alimentação de espécies criadas em aquacultura, mas alternativas com elevados valores nutricionais devem continuar a ser estudadas com o objetivo de melhor a performance de espécies cultivadas. Com isto em mente, este estudo sobre organismos macroinvertebrados associados a macroalgas foi elaborado para complementar o conhecimento relativamente a sistemas de produção multi-trófica, bem como o emprego da técnica de espectroscopia de infravermelhos (FTIR) para estudar o perfil metabólico através da identificação de compostos e grupos funcionais. A amostragem de invertebrados ocorreu no tanque de decantação da estação piloto de piscicultura de Olhão (IPMA), onde as macroalgas são abundantes. Três ocasiões de amostragem foram realizadas ao longo das estações do ano (Outono, Inverno e Primavera) com o propósito de observar se estas comunidades apresentam variações sazonais. As algas amostradas passaram por um processo de secagem, permitindo a análise da densidade de organismos por peso seco de alga. Algumas espécies de anfípodes e um isópode foram processados para análise espectrográfica, sendo primeiramente liofilizados e moídos. Esta moagem com adição de brometo de potássio (KBr) permitiu a criação de “pastilhas”, utilizadas na obtenção de espectros de absorvância. Os resultados obtidos mostram a dominância de Ulva spp., sendo a comunidade de invertebrados dominada por anfípodes, gastrópodes e isópodes. Foi possível observar variação sazonal da biomassa de algas por metro cúbico de água, da biomassa total de organismos, das densidades e dos índices de diversidade. Apesar da diminuição em biomassa de alga amostrada por volume entre o Outono e a Primavera (de 1820g m-3 para 852 g m-3), todos os outros parâmetros acima referidos apresentam a tendência inversa. As amostras recolhidas durante a Primavera parecem ser consideravelmente distintas das recolhidas no Outono, não só em termos de densidades de invertebrados, mas também na composição de espécies. A análise de ordenação MDS permitiu a observação de grupos por estação do ano, mas o mesmo não foi possível na diferenciação de zonas do tanque. Os resultados espectrográficos apresentam diferenças entre grupos taxonómicos processados (anfípodes e isópode), mas não entre fêmeas e machos da mesma espécie. Os resultados observados indicam que as macroalgas servem como fonte de habitat e alimento (direta ou indiretamente) para uma comunidade de invertebrados abundante e variada. Apesar disso os valores de diversidade e riqueza especifica são mais baixos comparativamente aos encontrados em estudos realizados em macroalgas e ervas marinhas em ambiente natural, podendo-se concluir que a comunidade presente no tanque de decantação é composta por organismos especializados. As espécies encontradas são na sua maioria detritívoras ou de pequenos herbívoros, estes organismos em associação com macroalgas podem contribuir para o tratamento de efluentes de aquacultura e promover o crescimento de alga no tanque. Tudo isto aliado à variação observada na comunidade de invertebrados ao longo do ano poderá ser explorada em termos de produção acessória, como alimento a fornecer na produção de espécies de interesse comercial.
This study received Portuguese national funds from CCMAR (FCT - Foundation for Science and Technology through project UID/Multi/04326/2019), project INTEGRATE Aquaculture: an eco-innovative solution to foster sustainability in the Atlantic Area (EAPA:232/2016 – INTERREG Atlantic Area 2014-2020), project DIVERSIAQUA (Mar2020 16-02-01-FMP-0066) and project DIVERSIAQUA II (MAR2020-P02M01-0656P). Miguel Ângelo Mateus – projeto MONIPOR/MESCLA - “Melhorar e complementar os critérios de classificação das massas de água de transição e costeiras” (APA-086/2018)

The close proximity of net-pen salmon farms and wild Pacific salmon stocks in British Columbia (BC) is an incentive for precautionary management of the environmentally and economically damaging parasites known as sea lice. Bivalves cultured as part of an integrated multi-trophic aquaculture (IMTA) system may contribute natural, preventative louse control through the ingestion of planktonic sea lice larvae. A field trial was conducted to test sea lice mitigation by bivalves at a commercial Atlantic salmon (Salmo salar) farm in BC using Pacific oysters (Crassostrea gigas). Oysters were cultured in trays around one end of the farm and at a reference site approximately 150 m away from August 2013 until August 2014. Parasitic and planktonic sea lice (Lepeophtheirus salmonis and Caligus clemensi) were monitored before and during oyster deployment, beginning in December 2012. Parasite abundance peaked in January 2013 (6.5 lice/fish, >85% C. clemensi), and the following year in February 2014 (3.3 lice/fish, >80% L. salmonis). Larval density within cages peaked in January, both in 2013 (1.28 larvae/m3) and 2014 (0.96 larvae/m3). Parasite abundance was significantly correlated with both surface salinity (r2= 0.28, p=0.04) and sea lice larval density (r2= 0.65, p=0.01). Observed densities were significantly lower (t=3.41, p=0.009) than those calculated for the site based on water temperature and salinity, the number of adult female lice present, and the approximate number of fish. Sea lice mitigation by oysters was assessed by comparing monthly sea lice larval densities inside bivalve and non-bivalve fish cages, and by analyzing preserved oyster digestive tracts from January 2014 (when larval densities were highest) for presence of L. salmonis DNA using PCR. Using these methods, no significant evidence of sea lice mitigation was detected. Oyster growth was monitored by measuring whole wet weight, soft tissue wet, dry, and ash-free dry weight, and shell length, width, and height approximately every four months. Oysters were sampled equally across different sides of the farm and at the reference site (~150 m away from the farm) at three depths: 1, 3, and 6 m. All seven measurements increased significantly over time. Effects of side and depth varied by growth parameter; in general, oysters at 1 and 3 m were significantly larger than those at 6 m, and oysters cultured at the reference site were either significantly smaller or the same size as those cultured around the farm. Oysters from select sides were consistently, significantly larger than those from other sides and from the reference site. Overall, the findings suggest that sea lice larvae quickly dispersed away from the farm after hatching and were not significantly impacted by bivalve presence around the fish cages. Bivalves grew significantly larger over time and size was significantly impacted by both depth and side of the fish cage. While no evidence of larval sea lice reduction/ingestion by cultured bivalves was detected, this study provides information on all sea lice stages present throughout an Atlantic salmon production cycle, as well as the first detailed growth analysis of Pacific oysters cultured alongside farmed Atlantic salmon in BC.
Graduate
0792
byrneaa@gmail.com

In land-based integrated aquaculture of marine finfish and macroalgae, rearing space is a large expense. Increasing algal stocking density can increase efficiency, but this may require greater irradiance because of self-shading. To determine the irradiance needed, experiments were conducted in one-litre flasks with enriched seawater under natural and artificial illumination. Under natural illumination, a Daily Photon Dose of 17 mol m-2 d-1 at 10 and 14 ºC, Palmaria palmata cultured at 10 g L-1 grew 100 % faster and absorbed 20 % more nutrients than Chondrus crispus. However, Atlantic halibut farm effluent can reach up to 19 ºC in summer, too high for P. palmata. Under artificial illumination, C. crispus performed better than under natural illumination. Light saturation curves indicated nutrient uptake by C. crispus at 10 g L-1 and 10 ºC was highest at 23 mol m-2 d-1 irradiance, equivalent to 400 µmol m-2 s-1 for 16 hours

As atividades aquícolas são uma parte integrante dos ecossistemas onde ocorrem, tendo um impacto inevitável no funcionamento dos mesmos. Certos modos de produção podem ter um impacto positivo acrescido na capacidade dos ecossistemas em providenciar serviços de regulação e manutenção, para além dos serviços mais óbvios de aprovisionamento de biomassa vegetal e animal. É o caso da Aquacultura Multi-Trófica Integrada (IMTA, do inglês Integrated Multi-trophic Aquaculture), uma estrutura de produção aquícola mais sustentável que pode ser definida como a produção otimizada de organismos aquáticos de dois ou mais grupos funcionais (com funções ecossistémicas complementares), ligados troficamente através de fluxos de energia e de nutrientes. Um desses grupos funcionais, que produzem serviços chave de fitoremediação, são as plantas halófitas. Capazes de suportar salinidades elevadas, as halófitas podem ser facilmente integradas em sistemas de IMTA em águas salinas como espécies extrativas com valor económico, podendo ser usada para a nutrição humana. A presente tese tem como objetivo principal testar a eficiência da halófita Halimione portulacoides (L.) Aellen na remoção de nutrientes (DIN e DIP, respetivamente do inglês dissolved inorganic nitrogen e dissolved inorganic phosphorus) presentes em soluções hidropónicas que simulam condições reais de efluentes de aquacultura, para avaliar a sua aptidão como espécie extrativa para a IMTA costeira. A produtividade e o potencial de valorização da planta são também demonstrados. O primeiro passo foi perceber o estado-da-arte relativamente ao uso de halófitas na remediação de efluentes aquícolas através de uma revisão sistemática da literatura. De seguida foram executados dois ensaios de crescimento em sistema hidropónico para perceber a capacidade extrativa e a produtividade do H. portulacoides. O primeiro ensaio consistiu num estudo exploratório da resposta da planta sob diferentes concentrações de DIN e DIP representativas de efluentes de aquacultura semiintensiva, intensiva e super-intensiva. O segundo ensaio foi desenhado de forma a providenciar dados adicionais sobre a influência da densidade de plantação e da iluminação no crescimento e na eficiência de remediação da planta. A partir da biomassa produzida foram analisados e caracterizados o perfil nutricional e o lipidoma da biomassa edível. Adicionalmente, foi realizado um inquérito estruturado a uma amostra de consumidores portugueses para avaliar as suas preferências e disponibilidade-a-pagar por halófitas embaladas e prontas a consumir e determinar potencias segmentos de consumidores destes novos produtos. Por fim, uma segunda revisão da literatura é apresentada onde se discute a utilidade de avaliar e valorar os serviços dos ecossistemas no contexto da aquacultura de modo a capturar o valor multidimensional de certos tipos de produção e promover práticas sustentáveis como o IMTA. Os resultados obtidos demonstram que as halófitas são plantas ainda subvalorizadas com imenso potencial no contexto da indústria alimentar no general, e da aquacultura em particular. No caso específico do H. portulacoides, as condições para a sua produção em hidroponia foram exploradas e, em condições nutricionais nãolimitantes, as unidades hidropónicas apresentaram uma produtividade de 54 – 73 g m-2 day-1, e eficiências de extração até 70% do DIN e 50% do DIP. A densidade de plantação pode ser ajustada de modo a aumentar a produtividade e capacidade extrativa das unidades hidropónicas. Além disso, o perfil nutricional das folhas é análogo ao de outras halófitas comestíveis e vegetais verdes e apresentou um perfil mineral baixo em sódio, apresentando-se como um pontencial substituto do sal. A análise do lipidoma polar permitiu identificar 175 espécies presentes no extrato lipídico das folhas. O questionário aos consumidores demonstrou que a disponibilidade média a pagar por uma embalagem de 50 g de Salicórnia pronta-a-consumir é de 2,10 €. O género feminino e o ‘consumidor aventureiro’ (baseado no instrumento de segmentação Food Related-Lifestyle) são dois segmentos de consumidores chave para os vegetais salgados. No geral, o H. portulacoides apresenta um bom desempenho de crescimento e extração de DIN e DIP em condições hidropónicas salinas (salinidade 20) e, portanto, é considerada uma espécie extrativa adequada para a IMTA costeira e apresenta elevado potencial para valoração económica. O conhecimento científico obtido fornece um ponto de partida sólido para o cultivo e ampliação da produção hidropónica de H. portulacoides.
Aquaculture activities are connected to some degree with the ecosystems on which they occur and from which they depend to operate, having an inevitable impact on their functioning. Certain modes of aquaculture production can have a positive impact on the capacity of ecosystems to deliver regulation and maintenance ecosystem services, besides the obvious provisioning services of biomass from aquatic plants and animals. This is certainly the case of Integrated Multi-Trophic Aquaculture (IMTA), a sustainable aquatic production framework, which can be defined as the enhanced production of aquatic organisms of two or more functional groups (with complementary ecosystem functions), that are trophically connected by demonstrated nutrient flows. One of these functional groups, with key ecosystem services of phytoremediation for IMTA, is halophyte plants. Capable of withstanding high salinities, halophytes can be easily integrated into saltwater based IMTA as extractive species and be developed into new valuable and nutritious crops with multiple uses in different industries. The main objective of this thesis was to test the capacity of the halophyte Halimione portulacoides to extract dissolved inorganic nitrogen (DIN) and phosphorous (DIP) from saline hydroponic solutions that mimic the conditions of real aquaculture effluents, to evaluate its suitability as an extractive species for coastal IMTA. The productivity and the valorization potential of the plant were also evaluated. The first step was to understand the state-of-the-art regarding the use of halophytes to remediate aquaculture effluents through a systematic review of the literature. Afterward, two hydroponic grow-out studies were designed and performed to understand the extractive capacity and production of H. portulacoides. The first trial was an exploratory study on the performance of this plant under different levels of DIN and DIP concentrations, mimicking those of semi-intensive, intensive, and super-intensive aquaculture effluents. The second trial was designed to further understand the influence of hydroponic production variables (plant density and artificial illumination) in the performance of H. portulacoides under non-limited nutrient conditions. From the biomass produced, further analyses were performed to characterize the leaves’ nutritional profile and lipidomic profile. Additionally, a structured survey was performed to a sample of Portuguese consumers to assess their preferences and willingnessto- pay for fresh-cut halophyte products and provide insight into potential consumer segments for these new products. At last, a second literature review was performed to understand the value of employing the ecosystem services framework to capture the multidimensional value of certain modes of aquaculture to foster more sustainable practices such as IMTA. The present work revealed that halophytes are undervalued crops with tremendous potential in the context of food production in general, and sustainable aquaculture in particular. In the specific case of H. portulacoides, the subject of this research, the conditions for its hydroponic production were explored. Under non-limited DIN and DIP conditions, hydroponic units displayed good productivity, varying between 54 – 73 g m-2 day-1, and extraction efficiencies up to 70% DIN and 50% DIP. Moreover, plant density can be optimized to improve the productivity and extractive capacity of hydroponic units. The nutritional profile of leaves is comparable to that of other edible halophytes and leafy greens and presents a low-sodium profile. A lipidomic analysis identified 175 polar lipid species present in the lipidic extract of the leaves. A survey of Portuguese consumers showed that average willingness-to-pay for a 50 g fresh-cut Salicornia package is 2.10 €. Female consumers and the ‘adventurous consumer’ (based on the Food-Related Lifestyle scale) are two major consumer segments for salty vegetables. Overall, the results obtained indicate that H. portulacoides performs well under saline hydroponic conditions, with efficient DIN and DIP extraction and high biomass production and is, therefore, a suitable extractive species for coastal IMTA and other hydroponic applications, with a high potential for economic valorization. The scientific knowledge obtained provides a solid starting point for H. portulacoides hydroponic production and scale-up towards commercial production.
Programa Doutoral em Ciência, Tecnologia e Gestão do Mar

This thesis details the spatial and temporal influence of integrated multi-trophic aquaculture-derived organic effluent on the diet of cultured organic extractive organisms within an integrated multi-trophic aquaculture (IMTA) facility in Kyuquot Sound, British Columbia. Naturally occurring and aquaculture-derived sources of nutrients were defined using isotopic analysis of δ15N and δ13C values, in order to examine feeding patterns of a cultured bivalve species C. gigas. By examining the diet of C. gigas located within the IMTA system, and at a reference site, spatial and temporal patterns of organic-effluent influence on organic extractive components within the IMTA system can be defined. Measurements were performed over four seasons (Spring, Summer, Autumn, and Winter) at a reference site and at stations adjacent to the fish component of the IMTA system, at distances of 0m, 15m, and 30m. Oysters at each station were suspended in the water column at depths of 6m and 18m. Chapter two of this thesis focuses on the vertical and horizontal patterns of aquaculture derived particulate waste influence on organic extractive components within the IMTA system. Examination of δ15N and δ13C values sampled from C. gigas tissue at each station indicated both horizontal and vertical dispersion, and subsequent uptake, of aquaculture-derived effluent. The importance of aquaculture-derived effluent to the diet of C. gigas was not uniform across stations or seasons. General trends indicate the strongest reliance upon aquaculture-derived effluent as a nutritional subsidy by C. gigas suspended at depths of 18m, and those located 15m and 30m adjacent to the fish component of the IMTA system in particular. This chapter also focuses on the examination of C. gigas feeding patterns using stable isotope analysis over a seasonal timescale, to describe temporal variability in the importance of aquaculture-derived effluent to the diet of organic extractive components within an IMTA system. Examination of δ15N and δ13C values sampled from C. gigas tissue at each station indicated strong seasonal shifts in importance of aquaculture-derived effluent as a nutritional subsidy to oysters within the IMTA system. General trends suggest that C. gigas cultured within the IMTA system feed most heavily upon aquaculture-derived effluent during the winter and spring months, while importance of naturally occurring food sources are more heavily relied upon during the summer and fall months. .
Graduate

The concept of recirculating aquaculture systems (RAS) is currently considered one of the paradigms of the Blue Revolution, as it allows to “grow fish anywhere”. One of the main constraints impairing the expansion of RAS, acknowledge to be a more environmentally friendly system, concerns the disposal of the organic rich effluent due to its high content in marine salts (circa 5-10% of the circulating water). The organic rich sediments that result from the settlement of suspended particulate matter (SPM) cannot be further used as fertilizer in traditional agriculture farms, being classified, according to Portuguese environmental legislation, as a dangerous waste. Therefore, it represents an economic burden to the fish farm. Integrated multi-trophic aquaculture (IMTA) has been regarded as a sustainable solution to overcome this constraint, being conceptually framed on an ecosystem-based approach. This concept involves the farming, in proximity, of aquaculture species from different trophic levels with complementary ecosystem functions. In IMTA one species uneaten feed and wastes, including nutrients and by-products, represents a source of energy to the next trophic level, enabling the combination of different extractive species. The present study aimed to test the efficiency of employing polychaete-assisted sand filters and halophytes in aquaponics in the removal of organic-rich SPM and dissolved inorganic nutrients present in a marine RAS effluent. In addition, the potential added value of selected extractive species was evaluated through their fatty acids (FA) profile. To achieve these goals, the present study was divided into four complementary steps: 1) test the capacity of an innovative approach, where Hediste diversicolor-assisted sand filters were combined with the production of Halimione portulacoides in aquaponics, to bioremediate an organic-rich effluent generated by a super intensive marine fish farm operating a land-based RAS; 2) evaluate the potential added value of RAS cultured H. diversicolor, by comparing their fatty acids (FA) profile with that of wild specimens; 3) evaluate, in terms of biosecurity, if high-pressure processing (HPP) of RAS cultured H. diversicolor, promoted significant changes on their FA content; 4) assess and compare FA profiles of RAS cultured halophytes, namely H. portulacoides, Salicornia ramosissima and Sarcocornia perennis with that of wild conspecifics from donor sites. The present study revealed that the proposed IMTA system, combining RAS cultured polychaetes H. diversicolor and the halophyte plants H. portulacoides, contributed to the bioremediation of the marine effluent. In detail, H. diversicolor-assisted sand filters promoted a decrease of particulate organic matter (POM) in 70%. The ability of H. diversicolor (extractive species) to retain high values of essential FA, namely 20:5n-3 e 22:6n-3 was also demonstrated. Moreover, 22:6n-3, an essential FA paramount for marine aquaculture species’ nutrition, is not found in wild specimens of H. diversicolor. The HPP treatment induced a small reduction on polychaetes HUFA levels, but without compromising their FA profile. In this way, HPP treatment ensures both biosecurity and the nutritional quality of polychaetes biomass for high-end products/applications. The halophyte H. portulacoides cultured in aquaponics displayed a pronounced growth of stem and leaves biomass, contributing to a decrease of waste water dissolved inorganic Nitrogen (DIN) in 65%. Furthermore, H. portulacoides cultured downstream from H. diversicolor-assisted sand filters promoted a superior decrease of DIN in effluent water (67%). Although H. portulacoides, S. ramosissima and S. perennis retained high-valued nutrients, their FA profile did not differ significantly from that of wild conspecifics. Both H. diversicolor and H. portulacoides show a high extractive capacity in IMTA systems for the biomitigation of super-intensive marine fish farms effluents. Selected extractive species display a high potential economic value, with their culture simultaneously contributing for reducing the dependence on wild species and promoting the circular economy agenda and more sustainable practices. The IMTA system implemented represents an important tool for the treatment of marine RAS effluents, as it in holds more sustainable management/practices. Overall, the IMTA system tested contributes to the prevention and reduction of marine pollution and to economic growth, in line with the United Nations Sustainable Development Goal 14 (SDG14 – “life below water”) for 2030.
Os sistemas de recirculação de aquacultura (RAS) são considerados um dos grandes paradigmas da Revolução Azul, pois permitem "cultivar peixes em qualquer lugar". A expansão destes sistemas RAS, levanta novos desafios face aos custos elevados associados ao tratamento do efluente gerado, existindo assim a necessidade de gestão do efluente orgânico devido ao seu teor de sal (cerca de 5-10% da água circulante). Os sedimentos removidos ricos em matéria orgânica não podem ser utilizados como fertilizantes agrícolas sem tratamento prévio. Deste modo, são encaminhados para estações de tratamento, à semelhança dos resíduos que são rotulados como perigosos para o ambiente de acordo com a legislação Portuguesa do ambiente. Esta imposição legal representa um custo adicional para o modelo produtivo que contemple o uso de RAS para cultivo de peixes marinhos. A aquacultura multi-trófica integrada (IMTA) surge como uma solução sustentável, baseada nos serviços fornecidos pelos ecossistemas. Este conceito envolve a cultura de espécies aquícolas de níveis tróficos diferentes, permitindo assim que os nutrientes presentes no alimento não ingerido e os resíduos produzidos sejam utilizados por outros organismos em cultivo. O presente estudo teve como objetivo testar a eficiência dos poliquetas cultivadas em tanques com filtros de areia e halófitas em aquaponia na remoção da matéria orgânica em suspensão e nutrientes na forma dissolvidos presentes no efluente de uma piscicultura a operar RAS em regime de produção super-intensivo, respetivamente. Pretendeu-se assim avaliar, através do perfil de ácidos gordos, o potencial valor das espécies extrativas escolhidas para este estudo. Este trabalho está dividido em quatro etapas complementares, nomeadamente: 1) testar uma abordagem inovadora de biomitigação com os poliquetas (Hediste diversicolor) cultivadas em filtros de areia combinadas com a produção da halófita Halimione portulacoides em aquaponia, na remediação de um efluente rico em matéria orgânica em suspensão e nutrientes na forma dissolvida; 2) avaliar o potencial valor acrescentado de H. diversicolor cultivado em tanques com filtros de areia abastecidos com o efluente da piscicultura comparando o seu perfil de ácidos gordos com o de conspecíficos selvagens; 3) determinar se o processamento com alta pressão (HPP) altera o teor de ácidos gordos nos poliquetas processados e validar este método para assegurar a biossegurança da biomassa destes organismos para fins comerciais; e 4) comparar os perfis de ácidos gordos de halófitas cultivados em aquaponia com o efluente de piscicultura com espécimes selvagens das áreas doadoras. Este estudo permitiu validar o potencial de H. diversicolor em tanques com filtros de areia e H. portulacoides em aquaponia na remediação do efluente da piscicultura. Os H. diversicolor cultivados em tanques com filtros de areia não só contribuíram para um decréscimo de 70% da matéria orgânica particulada, como também mostraram uma grande capacidade de reter valores elevados de ácidos gordos essenciais, nomeadamente 20:5n-3 e 22:6n-3 Estes ácidos gordos essenciais, considerados importantes para a nutrição das espécies de aquacultura, não foram encontradas em espécimes selvagens de H. diversicolor. O tratamento com altas pressões induziu uma pequena redução nas quantidades de ácidos gordos altamente insaturados nos poliquetas, no entanto não comprometeu o perfil de ácidos gordos. Desta forma, o tratamento HPP assegura tanto a biossegurança quanto a qualidade nutricional do produto final. As halófitas H. portulacoides cultivadas em aquaponia tiveram um crescimento acentuado nos caules e nas folhas, contribuindo para uma diminuição de 65% do azoto inorgânico dissolvido presente nos efluentes, subindo este valor para 67% quando combinadas com H. diversicolor. Estudos complementares com H. portulacoides, Salicornia ramosissima e Sarcocornia perennis revelaram que estas halófitas possuem uma grande capacidade para reter nutrientes, apresentando ainda um perfil em ácidos gordos n-3 e n-6 que não difere significativamente dos espécimes selvagens. As espécies H. diversicolor e H. portulacoides apresentam grande capacidade extrativa quando integradas em sistemas IMTA para a biomitigação de efluentes de pisciculturas a operar em regime super-intensivo. As espécies escolhidas representam um potencial valor económico, contribuindo a sua cultura para a redução da dependência da utilização de organismos selvagens, refletindo princípios de economia circular e práticas mais sustentáveis. O sistema IMTA implementado é assim uma ferramenta importante para o tratamento de efluentes, sendo igualmente uma contribuição positiva para a prevenção e redução da poluição marinha, gestão/práticas mais sustentáveis, segurança e crescimento económico, de acordo com o Objetivo de Desenvolvimento Sustentável 14 (ODS14 - “proteger a vida marinha”) proposto pelas Nações Unidas.
SFRH/BD/96037/2013
Programa Doutoral em Biologia

Achieving optimization of IMTA sites and modeling the efficiency of such a system requires knowledge of the spatiotemporal distribution and variability of TPM surrounding the finfish farms. The objective of this study was to quantify the impact of finfish farms on the surrounding particle field. Platforms equipped with transmissometers, fluorometers and CTD’s were towed around the sites while undulating through the water column in a high-resolution 3D spatial survey approach. In addition, combination turbidity and chlorophyll a sensors were moored at a variety of locations and depths. Surveys were conducted concurrently with the deployment of current meters. Farms surveyed were found to have little impact on the surrounding suspended particle field (mean effect < 1 mg L-1). Results provided evidence of minimal enhancement from fish farm wastes, primarily in surficial waters (0.5- 2 m depth) immediately adjacent to the cages, and evidence of predominantly tidal driven (M2) TPM dynamics.