Fish farms produce large amounts of wastes, including dissolved inorganic phosphorus and nitrogen. To exploit these nutrients as a resource input, and at the same time reduce the risk for ...eutrophication of the environment,
Gracilaria chilensis on ropes was co-cultivated with a salmon cage farm in southern Chile during two summer month.
Gracilaria cultivated at 10 m distance from the cages had up to 40% higher growth rate (specific growth rate; 7% day
−1) compared to growth at 150 m and 1 km distance. The algae nutrient content was also higher close to the cages (1.9–2.1 mmol N g
−1 dw
−1 and 0.28–0.34 mmol P g
−1 dw
−1) compared to the other stations. Yield of agar per unit biomass varied between 17–23% of dry weight and was lowest close to the farm, but due to higher growth rate, the accumulated agar production was highest close to the fish cages. The degree of epiphytes and bryozoa coverage was overall low. An extrapolation of the results showed that a 1 ha cultivation of the algae, close to the fish cages, had the potential to remove at least 5% of dissolved inorganic nitrogen released from the fish farm and 27% of released dissolved phosphorous. Such a cultivation would give an annual harvest of 34 dry t of
Gracilaria, worth 34000 US$. We conclude that both economical and environmental advantages can be achieved by integrating the cultivation of algae with fish farming in open sea systems. However, further studies focusing on full scale cultivation and functions during different seasons are needed.
Eco-certification is widely considered a tool for reducing environmental impacts of aquaculture, but what are the likely environmental outcomes for the world’s fastest growing animal-food production ...sector? This article analyzes a number of eco-certification schemes based on species choice, anticipated share of the global seafood market, size of eligible producers, and targeted environmental impacts. The potential of eco-certification to reduce the negative environmental impacts of aquaculture at scale presently appears uncertain as: (a) certification schemes currently focus on species predominantly consumed in the EU and US, with limited coverage of Asian markets; (b) the share of certified products in the market as currently projected is too low; (c) there is an inequitable and non-uniform applicability of certification across the sector; (d) mechanisms or incentives for improvement among the worst performers are lacking; and (e) there is incomplete coverage of environmental impacts, with biophysical sustainability and ecosystem perspectives generally lacking.
Freshwater prawn (Macrobrachium rosenbergii) farming in Bangladesh has, to a large extent, been dependent on the supply of wild larvae. Although there are 81 freshwater prawn hatcheries in the ...country, a lack of technical knowledge, inadequate skilled manpower, and an insufficient supply of wild broods have limited hatchery production. Many thousands of coastal poor people, including women, are engaged in fishing for wild prawn larvae along the coastline during a few months each year. On average, 40% of the total yearly income for these people comes from prawn larvae fishing activity. However, indiscriminate fishing of wild larvae, with high levels of bycatch of juvenile fish and crustaceans, may impact negatively on production and biodiversity in coastal ecosystems. This concern has provoked the imposition of restrictions on larvae collection. The ban has, however, not been firmly enforced because of the limited availability of hatchery-raised larvae, the lack of an alternative livelihood for people involved in larvae fishing, and weak enforcement power. This article discusses the environmental and social consequences of prawn larvae fishing and concludes that, by increasing awareness among fry fishers, improving fishing techniques (reducing bycatch mortality), and improving the survival of fry in the market chain, a temporal ban may be a prudent measure when considering the potential negative impacts of bycatch. However, it also suggests that more research is needed to find out about the impact of larvae fishing on nontarget organisms and on the populations of targeted species.
Marine ecosystem science has developed since the 1940s, when humans obtained the ability to spend substantial time underneath the surface of the ocean. Since then, and drawing on several decades of ...scientific advances, a number of exciting research frontiers have emerged. We find: Understanding interacting drivers of change, Identifying thresholds in ecosystems, and Investigating social-ecological dynamics to represent particularly interesting frontiers, which we speculate will soon emerge as new mainstreams in marine ecosystem science. However, increasing human impacts on ecosystems everywhere and a new level of global connectivity are shifting the context for studying, understanding, and managing marine ecosystems. As a consequence, we argue that ecosystem scientists today also need to address a number of critical challenges and devote new energy and expertise to Modeling the Anthropocene, Operationalizing resilience, and Understanding social-ecological dynamics across scales. This new deep dive into unknown waters requires a number of strategies to be successful. We suggest that marine ecosystem scientists need to actively: Prepare for the unexpected, cross boundaries, and understand our cognitive limitations to further develop the exciting field of marine ecosystem science.
The present study focuses on the Navachiste-San Ignacio-Macapule lagoon complex in northwest Mexico and evaluates the spatiotemporal change in the mangrove area over the last three decades using ...Landsat MSS and TM imagery. Local ethnobotanical uses of the mangrove forest and local perceptions about the status and recent development of the mangrove forest cover are also analyzed. The results of interviews with 54 inhabitants of four fishing villages in the study area indicated that, overall,Laguncularia racemosais the most frequently used species in this region of the Mexican Pacific coast, where it serves as firewood and a construction material, particularly for walls and fences. The next-ranked species wereAvicennia germinans, which is used for tea, andRhizophora mangle, which is used for tanning; both these species also serve medicinal purposes. There was a discrepancy between the assessment of actual changes in the mangrove cover and what people perceived them to be. These findings are discussed from a socioeconomic (utilization) and an ecological (functionality) point of view and in relation to the use of remote sensing as a tool. The utilization pattern is also discussed against the background of mangrove cover variation.
Global seafood provides almost 20% of all animal protein in diets, and aquaculture is, despite weakening trends, the fastest growing food sector worldwide. Recent increases in production have largely ...been achieved through intensification of existing farming systems, resulting in higher risks of disease outbreaks. This has led to increased use of antimicrobials (AMs) and consequent antimicrobial resistance (AMR) in many farming sectors, which may compromise the treatment of bacterial infections in the aquaculture species itself and increase the risks of AMR in humans through zoonotic diseases or through the transfer of AMR genes to human bacteria. Multiple stakeholders have, as a result, criticized the aquaculture industry, resulting in consequent regulations in some countries. AM use in aquaculture differs from that in livestock farming due to aquaculture’s greater diversity of species and farming systems, alternative means of AM application, and less consolidated farming practices in many regions. This, together with less research on AM use in aquaculture in general, suggests that large data gaps persist with regards to its overall use, breakdowns by species and system, and how AMs become distributed in, and impact on, the overall social-ecological systems in which they are embedded. This paper identifies the main factors (and challenges) behind application rates, which enables discussion of mitigation pathways. From a set of identified key mechanisms for AM usage, six proximate factors are identified: vulnerability to bacterial disease, AM access, disease diagnostic capacity, AMR, target markets and food safety regulations, and certification. Building upon these can enable local governments to reduce AM use through farmer training, spatial planning, assistance with disease identification, and stricter regulations. National governments and international organizations could, in turn, assist with disease-free juveniles and vaccines, enforce rigid monitoring of the quantity and quality of AMs used by farmers and the AM residues in the farmed species and in the environment, and promote measures to reduce potential human health risks associated with AMR.
Regime shifts and management Crépin, Anne-Sophie; Biggs, Reinette; Polasky, Stephen ...
Ecological economics,
12/2012, Volume:
84
Journal Article
Peer reviewed
Regime shifts are substantial reorganizations in system structure, functions and feedbacks, which can lead to changes in the provision of ecosystem services with significant impacts on human ...well-being. Recent research has documented cases of regime shifts in local and regional systems and there is mounting concern about regime shifts of global significance. In this paper we discuss management of social–ecological systems in light of the potential for regime shift. Management that increases system resilience and lowers the probability of regime shifts is beneficial when regime shifts are likely to reduce human well-being. It may not always be possible to avoid harmful regime shifts, so building capacity to adapt should a regime shift occur is beneficial too. Adaptive management can help reduce uncertainty about the likelihood of regime shifts, how this likelihood can be affected by management action, and the impact of regime shifts on well-being. Linking scientific understanding with decision-making is important but distributional consequences can impede decision making and action.
► Evidence suggests increased occurrence of regime shifts in social–ecological systems. ► Regime shifts often impact significantly on ecosystem services and human well-being. ► Managing regime shifts focuses on both prevention and building adaptive capacity. ► Adaptive management can help reduce uncertainty about regime shifts. ► Distributional consequences of regime shifts can impede decision-making and action.
Seafood is seen as promising for more sustainable diets. The increasing production in land-based closed Recirculating Aquaculture Systems (RASs) has overcome many local environmental challenges with ...traditional open net-pen systems such as eutrophication. The energy needed to maintain suitable water quality, with associated emissions, has however been seen as challenging from a global perspective. This study uses Life Cycle Assessment (LCA) to investigate the environmental performance and improvement potentials of a commercial RAS farm of tilapia and Clarias in Sweden. The environmental impact categories and indicators considered were freshwater eutrophication, climate change, energy demand, land use, and dependency on animal-source feed inputs per kg of fillet. We found that feed production contributed most to all environmental impacts (between 67 and 98%) except for energy demand for tilapia, contradicting previous findings that farm-level energy use is a driver of environmental pressures. The main improvement potentials include improved by-product utilization and use of a larger proportion of plant-based feed ingredients. Together with further smaller improvement potential identified, this suggests that RASs may play a more important role in a future, environmentally sustainable food system.
Global demand for freshwater and marine foods (i.e., seafood) is rising and an increasing proportion is farmed. Aquaculture encompasses a range of species and cultivation methods, resulting in ...diverse social, economic, nutritional, and environmental outcomes. As a result, how aquaculture develops will influence human wellbeing and environmental health outcomes. Recognition of this has spurred a push for nutrition-sensitive aquaculture, which aims to benefit public health through the production of diverse, nutrient-rich seafood and enabling equitable access. This article explores plausible aquaculture futures and their role in nutrition security using a qualitative scenario approach. Two dimensions of economic development - the degree of globalization and the predominant economic development philosophy - bound four scenarios representing systems that are either localized or globalized, and orientated toward maximizing sectoral economic growth or to meeting environmental and equity dimensions of sustainability. The potential contribution of aquaculture in improving nutrition security is then evaluated within each scenario. While aquaculture could be "nutrition-sensitive" under any of the scenarios, its contribution to addressing health inequities is more likely in the economic and political context of a more globally harmonized trade environment and where economic policies are oriented toward social equity and environmental sustainability.
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