A design and management approach for horizontally integrated aquaculture systems

This thesis presents an assessment concerning the potential of horizontally integrated aquaculture, with outcomes assessed from a systems-based perspective. A literature review concerning the negative impacts and the limitations of current wastewater management approaches demonstrated that improved strategies are required. Horizontally integrated aquaculture was proposed, where the productive reuse of aquaculture wastewater ameliorates associated negative impacts. A definition for horizontally integrated aquaculture is presented and management strategies that conform to this definition reviewed. The development and application of the ADEPT bioeconornic model to assess the potential of a constructed wetland and trout fishery to treat wastewater from a commercial smolt unit in Scotland is described. The model outputs were tested against observations from commercial facilities operating under comparable conditions to those envisaged for horizontally integrated systems. Findings demonstrated that the modelling approach adopted was generally effective in predicting the composition of wastewater outputs from the farm and the effect of the selected treatment strategies. The model was applied to two further case studies. One assessed the potential of treating wastewater from shrimp farms in Thailand using a constructed mangrove wetland; the second evaluated the possible advantages of a rational design approach to lagoon-based wastewater treatment and reuse, as opposed to a conventional design and traditional practices developed in peri-urban Calcutta

Evaluating sustainable intensification and diversification options for agriculture-based livelihoods within an aquatic biodiversity conservation context in Buxa, West Bengal, India

Potential impacts of sustainable intensification and diversification options for agriculture-based livelihoods in Buxa, West Bengal, India were evaluated using bioeconomic modelling. The baseline scenario involved multiple cropping seasons and a combination of crops on 0.9 ha landholdings, livestock husbandry, and exploitation of common property resources. With capital costs of Rs. 128,180 (US$2293) and annual operating costs of Rs. 37,290 (US$ 667), the net benefit generated (excluding depreciation) was Rs. 70,250 (US$1257) annually. The pay-back period was 1.8 years, and the Internal Rate of Return (IRR) was 53.7$ 1,342) and IRR to 56.5% with minimal added costs and risks. Adopting the system of rice intensification (SRI) for paddy cultivation on 0.35 ha increased the IRR to 61.1%, while reducing agrochemical and inorganic fertiliser use. Including small-scale fish culture in a 0.1 ha pond integrated in the irrigation scheme for SRI cultivation resulted in an IRR of 77.3% and reduced the pay-back period to 1.3 years. Some risks to biodiversity are apparent with each scenario; however, with appropriate safeguards, sustainable agricultural intensification and livelihoods diversification could bolster agrobiodiversity and social-ecological resilience of highland communities, while alleviating pressure on biodiversity

Evaluating the potential of innovations across aquaculture product value chains for poverty alleviation in Bangladesh and India

Evidence is presented that innovation across aquaculture value chains can contribute to poverty reduction through income generation and increased consumption of nutritious aquatic foods. Innovation is defined and contextualized in relation to aquaculture development. Opportunities for aquaculture innovation across value chains for poverty reduction and sustainable production are described. Contemporary trends in aquaculture development in Bangladesh and India, with a focus on 2011-2020, are reviewed, as understanding transformative change to aquatic food systems during this period could benefit millions of poor and marginal consumers. Market-led commercial production, instigated by private sector entrepreneurs for domestic markets, has underpinned the surge in freshwater fish culture in key geographical locations. In contrast booms in shrimp production have been associated with export opportunities and related cycles of boom-and-bust have been described, with busts attributed to falling market prices and disease outbreaks. Innovation could safeguard supplies of affordable fish to poorer groups (especially young children and pregnant and breastfeeding women) and enable better health management of aquatic animals including coordination of surveillance and disease control measures. Innovation to effectively promote better management practices and integrated services provision to large numbers of small- and medium-scale producers could contribute to poverty reduction. Opportunities for future innovation to ensure that aquaculture development is sustainable are critically reviewed. Innovative strategies to add value to byproducts and utilize waste resources could avoid negative environmental impacts, recycle nutrients and create income generating opportunities. A new paradigm for development assistance that identifies and supports promising innovation trajectories across jurisdictions, product value chains, institutional regimes and food systems is needed. Government agencies must be responsive to the needs of businesses throughout aquatic food systems and devise policies and regulatory regimes that support transformative and sustained growth of the aquaculture sector. Investment in capacity-building, education, research and training and action to promote an enabling institutional environment must be regarded as essential elements to maximize and share equitably the benefits arising and avoid potential negative impacts of inappropriate innovations

Can greening of aquaculture sequester blue carbon?

Globally, blue carbon (i.e., carbon in coastal and marine ecosystems) emissions have been seriously augmented due to the devastating effects of anthropogenic pressures on coastal ecosystems including mangrove swamps, salt marshes, and seagrass meadows. The greening of aquaculture, however, including an ecosystem approach to Integrated Aquaculture-Agriculture (IAA) and Integrated Multi-Trophic Aquaculture (IMTA) could play a significant role in reversing this trend, enhancing coastal ecosystems, and sequestering blue carbon. Ponds within IAA farming systems sequester more carbon per unit area than conventional fish ponds, natural lakes, and inland seas. The translocation of shrimp culture from mangrove swamps to offshore IMTA could reduce mangrove loss, reverse blue carbon emissions, and in turn increase storage of blue carbon through restoration of mangroves. Moreover, offshore IMTA may create a barrier to trawl fishing which in turn could help restore seagrasses and further enhance blue carbon sequestration. Seaweed and shellfish culture within IMTA could also help to sequester more blue carbon. The greening of aquaculture could face several challenges that need to be addressed in order to realize substantial benefits from enhanced blue carbon sequestration and eventually contribute to global climate change mitigation

Fish acquisition and consumption in the African Great Lakes Region through a food environment lens: A scoping review

Effective actions for the fishery and aquaculture sectors to contribute toward improving nutrition rely on an understanding of the factors influencing fish intake, particularly amongst vulnerable populations. This scoping review synthesises evidence from 33 studies in the African Great Lakes Region to examine the influence of food environments on fish acquisition and consumption. We identified only two studies that explicitly applied a food environment framework and none that linked policy conditions with the contribution of fish to diets. Economic access to fish was represented in the largest number of included studies (21 studies), followed by preferences, acceptability and desirability of fish (17 studies) and availability and physical access (14 studies). Positive perceptions of taste and low cost, relative to other animal-source foods, were drivers of fish purchases in many settings; however, limited physical and economic access were frequently identified as preventing optimal intake. In lakeside communities, fish were increasingly directed toward external markets which reduced the availability and affordability of fish for local households. Few studies considered intra-household variations in fish access according to age, gender or physiological status, which represents an important knowledge gap. There is also scope for future research on seasonal influences on fish access and the design and rigorous evaluation of programmes and policies that address one or more constraints of availability, cost, convenience and preferences

Floodplain management in temperate regions : is multifunctionality enhancing biodiversity?

Background: Floodplains are among the most diverse, dynamic, productive and populated but also the most threatened ecosystems on Earth. Threats are mainly related to human activities that alter the landscape and disrupt fluvial processes to obtain benefits related to multiple ecosystem services (ESS). Floodplain management therefore requires close coordination among interest groups with competing claims and poses multi-dimensional challenges to policy-makers and project managers. The European Commission proposed in its recent Biodiversity Strategy to maintain and enhance European ecosystems and their services by establishing green infrastructure (GI). GI is assumed to provide multiple ecosystem functions and services including the conservation of biodiversity in the same spatial area. However, evidence for biodiversity benefits of multifunctional floodplain management is scattered and has not been synthesised. Methods/design: This protocol specifies the methods for conducting a systematic review to answer the following policy-relevant questions: a) what is the impact of floodplain management measures on biodiversity; b) how does the impact vary according to the level of multifunctionality of the measures; c) is there a difference in the biodiversity impact of floodplain management across taxa; d) what is the effect of the time since implementation on the impact of the most important measures; and e) are there any other factors that significantly modify the biodiversity impact of floodplain management measures? Within this systematic review we will assess multifunctionality in terms of ESS that are affected by an implemented intervention. Biodiversity indicators included in this systematic review will be related to the diversity, richness and abundance of species, other taxa or functional groups. We will consider if organisms are typical for and native to natural floodplain ecosystems. Specific inclusion criteria have been developed and the wide range of quality of primary literature will be evaluated with a tailor-made system for assessing susceptibility to bias and the reliability of the studies. The review is intended to bridge the science-policy interface and will provide a useful synthesis of knowledge for decision-makers at all governance levels

Recipient mucosal-associated invariant T cells control GVHD within the colon

Mucosal-associated invariant T (MAIT) cells are a unique innate-like T cell subset that responds to a wide array of bacteria and yeast through recognition of riboflavin metabolites presented by the MHC class I–like molecule MR1. Here, we demonstrate using MR1 tetramers that recipient MAIT cells are present in small but definable numbers in graft-versus-host disease (GVHD) target organs and protect from acute GVHD in the colon following bone marrow transplantation (BMT). Consistent with their preferential juxtaposition to microbial signals in the colon, recipient MAIT cells generate large amounts of IL-17A, promote gastrointestinal tract integrity, and limit the donor alloantigen presentation that in turn drives donor Th1 and Th17 expansion specifically in the colon after BMT. Allogeneic BMT recipients deficient in IL-17A also develop accelerated GVHD, suggesting MAIT cells likely regulate GVHD, at least in part, by the generation of this cytokine. Indeed, analysis of stool microbiota and colon tissue from IL-17A–/– and MR1–/– mice identified analogous shifts in microbiome operational taxonomic units (OTU) and mediators of barrier integrity that appear to represent pathways controlled by similar, IL-17A–dependent mechanisms. Thus, MAIT cells act to control barrier function to attenuate pathogenic T cell responses in the colon and, given their very high frequency in humans, likely represent an important population in clinical BMT