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  • Sarcocornia neei: A novel halophyte species for bioremediation of marine aquaculture wastewater and production diversification in integrated systems

    The integration of bioremediation systems is one of the most promising techniques to mitigate the environmental impact of aquaculture effluents. Also, it allows nutrient recycling, production diversification, and the creation of high-value by-products. In marine aquaculture, where the implementation of salt-tolerant extractive species is essential, halophyte plants have demonstrated to be optimal candidates for bioremediation of saline aquaculture wastewater.

    This study aimed to evaluate for the first time the efficiency of Sarcocornia neei (Lag.), a halophyte plant with high adaptability, salinity tolerance and growth potential when irrigated with seawater, in removing nutrients from marine fish aquaculture wastewater and artificial effluents. Two experiments were carried out. In the first one, the growth rate, removal of inorganic nutrients, and accumulation of organic compounds in deep-water hydroponics and sand-substrate systems were evaluated in artificial effluents with different nitrogen and phosphate loads during 70 days. In the second, due to the better performance achieved by S. neei in deep-water systems, its nitrogen removal efficiency and productivity rates were evaluated in deep-water aquaponics with marine aquaculture wastewater and artificial effluents at higher nitrogen loads during 61 days.

    The highest productivity rates achieved by S. neei (14.41 ± 0.78 kg m−2) were obtained in deep-water culture units, reaching 100% plant survival, suggesting that this species is more suitable for its implementation in this type of system. Significant total ammonia nitrogen removal rates were obtained by the plants, achieving a maximum in sand-substrate systems (0.68 ± 0.41 g m−2 day−1). The results of nitrate removal rates obtained by S. neei (11.25 ± 31.38 g m−2 day−1) make this species an ideal potential candidate for the removal of this compound present in marine RAS effluents. Accumulation of organic compounds was corroborated by obtaining a significant increase (p < 0.05) in organic N (31.2 ± 0.1 mg g dry weight−1) and organic P (4.0 ± 0.6 mg g dry weight−1) content in plant biomass at the end of the trials.

    These results indicated that S. neei is a good candidate for its use as a biofilter for marine aquaculture wastewater. Further investigations should be done to analyze possible influences on growth rates and nutrient removal efficiency by adding essential micronutrients, adjusting effluent salinity, and implementing different plant densities. Also, further studies could be interesting to determine the feasibility of long-term integration of a bioremediation system with S. neei associated with marine aquaculture effluents, approaching its application to industrial-scale production systems.

    Author(s): Clemens Pascal Beyer, Silvia Go ́mez, Gabriele Lara, Juan Pablo Monsalve, Jaime Orellan, Carlos Felipe Hurtado

  • Role of deposit feeders in integrated multi-trophic aquaculture — A model analysis

    The performance of deposit feeders in integrated multi-trophic aquaculture (IMTA) was analysed through the ap- plication of mathematical models. Loading of organic particulates to the benthos as a result of finfish cage culture and shellfish suspended culture was analysed by means of a deposition model (ORGANIX), and an individual model for growth and environmental effects was developed for the California sea cucumber Parastichopus californicus. Following validation, the model was combined with existing models for finfish, shellfish, and macroalgae into a framework for simulation of IMTA interactions at the local scale. Several scenarios for different culture combinations and densities were simulated using the Farm Aquaculture Resource Management (FARM) model, using a layout which reflects typical stocking densities and spatial occupation in Europe and North America. The model allows an analysis of the different sources and fate of particulate organic matter associated with distinct culture groups. Our results illustrate the production enhancement for deposit feeders cultivated below both finfish (600%) and shellfish (150%). Furthermore, sea cucumbers are responsible for a significant re- moval of the particulate organic carbon loading to the bottom, reducing the gross load by up to 86% for finfish culture and 99% for shellfish culture. The role of cultivated seaweeds in reducing the dissolved nitrogen concen- tration in the farm area was also examined—no significant reduction in ambient nutrient concentration was ob- served, but the added nitrogen provides a clear stimulus (22% increase) to kelp production. By contrast, shellfish grown in suspended culture in the vicinity of finfish cages show very little change in individual growth or har- vestable biomass. This work helps to analyse the ecological and economic potential of various forms of IMTA, and the role of co-cultivation in direct extraction and re-use of materials and energy at both the local (farm) and system (bay, estuary) scales.

    Statement of relevance: Analysis of the ecological and economic potential of various forms of IMTA, and the relevance of co-cultivation in direct extraction and re-use of materials and energy at both the local (farm) and system (bay, estuary) scales. FARM model framework applied to understand the roles of suspended bivalve culture and benthic deposit-feeder culture in mitigating the negative externalities of finfish culture.

    Author(s): A.M. Cubillo, J.G. Ferreira, S.M.C. Robinson, C.M. Pearce, R.A. Corner, J. Johansen

  • Role of Aquaculture in Increasing Water Productivity

    Aquaculture, the farming of aquatic animals and plants, is a well-established industry in many parts of the world. Aquaculture has, in fact, replaced inland capture fisheries as the most important source of freshwater fish (Revenga et al. 2000). According to FAO statistics, aquaculture's contribution to global supplies of freshwater and marine species has grown from 3.9 percent of total production by weight in 1970 to 27.3 percent in 2000. Overall, aquaculture has increased at an average compounded rate of 9.2% per year since 1970, compared with only 1.4% for capture fisheries and 2.8% for terrestrial animal production (FAO 2002). In 2000, total aquaculture production reported to FAO was 45.7 million metric tons with a value of $56.5 billion US dollars. Almost half of the total, some 20.2 million metric tons was produced in freshwater (Figure 1).

    Author(s): Randall E. Brummett

  • Risk and Risk Management for Feed and Seed for Marine Fish Raised in Offshore Aquaculture

    For open ocean aquaculture of marine fish, the provision of feed and seed occurs externally
    to the actual fish culture operation. How these external activities are conducted and applied determines the potential ecological impact for the industry as a whole. Ecological risks associated with marine aquaculture may be addressed using a framework similar to that used for assessment of risks in other areas of our lives. The use of a framework developed for the World Health Organization (WHO) for assessment of risk to human health from various threats has been proposed for assessment of risk to the environment from marine aquaculture    1. The identification and characterization of risk are the first steps in determining what risk management strategies might be the most productive in developing supplies of feed and seed for offshore aquaculture that are low risk and will be stable and dependable over the long run. For each risk, the WHO risk assessment framework may be applied to focus research and development on strategies that could be used to reduce or eliminate risk. In most cases, multiple options exist for risk reduction. Risk management strategies that improve economic gain and reduce or eliminate multiple ecological risks, however, are preferred and they have a much higher chance of resulting in meaningful improvements. Furthermore, strategies that allow improvement, or change over the long term, provide more flexible and ultimately sustainable solutions. In most cases, research is needed to develop better risk management strategies. Up-front costs associated with research, development, and implementation often limit application of risk management strategies to industries large enough to afford these costs even if there are long-term economic benefits associated. This is especially true when governments do not fund this type of research and development.

    Author(s): Michael B. Rust

  • Revisiting the economic profitability of giant kelp Macrocystis pyrifera (Ochrophyta) cultivation in Chile

    The demand for seaweed biomass for hydrocolloid industries and novel products for the food, pharmaceutical, cosmetics and agro-industry has been steadily increasing during the last decade. This trend is expected to continue into the future as new uses are discover and the ever-increasing human population needs for healthy products and clean energy expand beyond land-based resources. Seaweed farming still faces constraints for its development and one of them is its economic profitability as in general the seaweed biomass has a rather low value with few exceptions of some species used for human consumption. Therefore, there is a need to increase production of seaweed biomass, but there is still a lack of realistic economic assessments that determine the economic potentiality of a seaweed farming project to attract investors. This article reports an economic model, fed with data of a pre-commercial Macrocystis pyrifera 21-ha pilot farm installed in southern Chile. The economic sensitivity analysis revealed that cultivation of M. pyrifera in southern Chile is profitable in a 10-ha cultivation system when the market price is at least US$ 87 wet t−1 and yields are kept at a minimum of 12.4 kg m−1. We discuss the potential that seaweed cultivation has in Chile and we agree with previous studies that value, productivity and the farming model used are key factors for the economic success of seaweed farming.

    Author(s): Carolina Camus, Javier Infante, Alejandro H. Buschmann

  • Review: Production of Gracilaria parvispora in two-phase polyculture systems in relation to nutrient requirements and uptake

    Gracilaria parvispora Abbott is highly valued in Hawaiian seafood markets. Due to the over-harvesting of natural beds. G. parvispora is scarce on the open reef ; and harvesting is strictly regulated. On Molokai, Hawaii, a community-based operation was established to develop a sustainable, integrated culture system for this species. Previous research suggested that ammonium was the limiting factor for sufficient growth on the reef. Therefore, on Molokai, a polyculture system was developed using fish/shrimp ef- fluent to load thalli with nitrogen before placement in a low-nutrient lagoon for grow- out. The research described here demonstrates how small-scale, commercial culture of seaweed can be successfully integrated with the production of fish and shrimp. Two benefits of a two-phase polyculture system are: 1) a waste product from the first phase (i.e. ammonia nitrogen) becomes a resource for the second phase and 2) integrated sys- tems are financially more stable because of improved cash-flow and product diversifica- tion. A modest biomass of fish can support a substantial production of seaweed. The type of cage-based, polyculture system developed on Molokai could be applicable to other rural coastal areas.

    Author(s): Erin RYDER, Stephen NELSON, Edward GLENN, Pamela NAGLER, Sherman NAPOLEAN, Kevin FITZSIMMONS

  • Review of environmental impact, site selection and carrying capacity estimation for small scale aquaculture in Asia

    Asia is the leading aquaculture region in the world, contributing to 85% of total world aquaculture production. Of the top 10 aquaculture producing countries 9 are Asian with China accounting for more than 65% of Asian production. Aquaculture in Asia contribute more than 80% of an estimated 17-20 million aquaculture farmers in Asia providing livelihoods, food security and export earning power but at the same time there are growing problems with environmental impact from large numbers of small-scale producers and the difficulties in planning and management of further development. Traditional integrated aquaculture systems which are sustainable environmentally continue to play an important role for many small-scale farmers and local communities, particularly at the subsistence level. However, recently more productive and profitable aquaculture practices have developed using formulated pelleted feed and allowing intensification of production. Small-scale producers are characterised small farm units and low productivity but in many cases, aquaculture develops in clusters of small-scale farms favouring sheltered bays, estuarine areas and coastal fringe, lakes and dams. Whilst individually such farms create little environmental impact, the cumulative effects of large numbers of farms in “clusters” can be significant. Mitigation of these environmental impacts is difficult due to the number of individual small scale-farmers. However the effects of cumulative environmental impact can be reduced by the introduction of carrying capacity estimation using models before development, the implementation of Better Management Practices and control of feed quality and feeding strategy and management can reduce the cumulative impact.

    Author(s): Malcolm Beveridge, Patrick White, Michael Phillips

  • Results of Environmental Monitoring at an Experimental Offshore Farm in the Gulf of Maine: Environmental Conditions after Seven Years of Multi-Species Farming

    The University of New Hampshire, in partnership with local fishing cooperatives and a commercial marine fish hatchery, and with collaboration from several regional research institutions, established an offshore aquaculture research and development facility in the Gulf of Maine in 1999. The offshore platform, located 9.66 km (6 miles) off the New Hampshire coastline in 56.39 m (185 feet) of water, is fully permitted for commercial production. It consists of a submerged

    grid mooring system that can accommodate four submersible cages for finfish culture, two submerged longlines for suspended molluscan shellfish culture, and surface structures that include remotely operated feeders, acoustic biotelemetry systems, and oceanographic instrumentation.
    The facility serves as the field site for applied research and technology development, evaluation, and technology transfer for the Open Ocean Aquaculture Project funded by the National Oceanic and Atmospheric Administration. The goal of the project is to stimulate the development of an environmentally sustainable offshore aquaculture industry, thereby increasing seafood production, creating new employment opportunities, and contributing to regional and national economic and community development. To date, fish species cultured at the site have included summer flounder (    Paralichthyus dentatus), Atlantic halibut (Hippoglossus hippoglossus), haddock (Melanogrammus aeglefinis), and Atlantic cod (Gadus morhua). In addition, blue mussels (Mytilus edulis) and Atlantic sea scallops (Placopecten magellanicus) have been grown on the adjacent submerged longlines.

    Author(s): Richard Langan

  • Responsible Aquaculture in 2050: Valuing Local Conditions and Human Innovations Will Be Key to Success

    As aquaculture production expands, we must avoid mistakes made during increasing intensification of agriculture. Understanding environmental impacts and measures to mitigate them is important for designing responsible aquaculture production systems. There are four realistic goals that can make future aquaculture operations more sustainable and productive: (1) improvement of management practices to create more efficient and diverse systems at every production level; (2) emphasis on local decisionmaking, human capacity development, and collective action to generate pro- ductive aquaculture systems that fit into societal constraints and demands; (3) development of risk management efforts for all systems that reduce disease problems, eliminate antibiotic and drug abuse, and prevent exotic organism introduction into local waters; and (4) creation of systems to better identify more sustainably grown aquaculture products in the market and promote them to individual consumers. By 2050, seafood will be predominantly sourced through aquaculture, including not only finfish and invertebrates but also seaweeds.

    Author(s): James S. Diana,, Hillary S. Egna, Thierry Chopin, Mark S. Peterson, Ling Cao, Robert Pomeroy, Marc Verdegem, William T. Slack, Felipe Cabello, Melba G. Bondad-Reantaso

  • Responses of the germination and growth of Ulva prolifera parthenogametes, the causative species of green tides, to gradients of temperature and light

    Responses of the germination and growth of Ulva prolifera parthenogametes to gradients of temperature and light were evaluated. Results showed that U. prolifera parthenogametes could not germinate at 5 °C and 35 °C, and at all temperatures combined with dark conditions, but had high germination rates at the temperature of 15–25 °C and photosynthetically active radiation (PAR) of 80–160 μmol m–2 s–1. There was a significant interaction between temperature and PAR on the growth rate of U. prolifera germlings germinated from parthenogametes (P < 0.001), which indicated that U. prolifera germlings achieved the highest growth rate at specific combinations of temperature and light. Growth rate of U. prolifera germlings germinated from parthenogametes was as high as 93.5–99.2 % d−1 at combined conditions of 22 °C and 26 °C with 100 μmol m−2·s−1 and 200 μmol m−2·s−1, respectively. Ulva prolifera parthenogametes survived over two months at the temperature of 3 °C, and germinated and grew when the temperature increased from 3 °C to 13 °C. Ulva prolifera thalli germinated from parthenogametes maintained a relatively better state under the condition of 30 °C and 10 μmol m−2·s−1 compared with thalli cultured at 30 °C combined with PAR of 100 μmol m−2·s−1 and 200 μmol m−2·s−1, respectively. These results suggest that U. prolifera parthenogametes may largely contribute to green tides due to their high germination and growth rates, and their ability to survive over stressful environments in the southern Yellow Sea.

    Author(s): Yarish, Charles Peimin He, Simona Augyte, Jang Kyun Kim, Yuanzi Huo

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