Oyster aquaculture helps mitigate oceanic pollution through biofiltration.
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Peer-reviewed literature indicates that oyster and shellfish aquaculture provides nutrient bioremediation and improves water quality by filtering nutrients from coastal waters.
The rapid development of intensive fed aquaculture (e.g. finfish and shrimp) throughout the world is associated with concerns about the environmental impacts of such often monospecific practices, especially where activities are highly geographically concentrated or located in suboptimal sites whose assimilative capacity is poorly understood and, consequently, prone to being exceeded. One of the main environmental issues is the direct discharge of significant nutrient loads into coastal waters from open‐water systems and with the effluents from land‐based systems. In its search for best management practices, the aquaculture industry should develop innovative and responsible practices that optimize its efficiency and create diversification, while ensuring the remediation of the consequences of its activities to maintain the health of coastal waters. To avoid pronounced shifts in coastal processes, conversion, not dilution, is a common‐sense solution, used for centuries in Asian countries. By integrating fed aquaculture (finfish, shrimp) with inorganic and organic extractive aquaculture (seaweed and shellfish), the wastes of one resource user become a resource (fertilizer or food) for the others. Such a balanced ecosystem approach provides nutrient bioremediation capability, mutual benefits to the cocultured organisms, economic diversification by producing other value‐added marine crops, and increased profitability per cultivation unit for the aquaculture industry. Moreover, as guidelines and regulations on aquaculture effluents are forthcoming in several countries, using appropriately selected seaweeds as renewable biological nutrient scrubbers represents a cost‐effective means for reaching compliance by reducing the internalization of the total environmental costs. By adopting integrated polytrophic practices, the aquaculture industry should find increasing environmental, economic, and social acceptability and become a full and sustainable partner within the development of integrated coastal management frameworks.
Rising global demand for seafood and declining catches have resulted in the volume of mariculture doubling each decade, a growth expected by the FAO to persist in the decades to come. This growth should use technologies with economical and environmental sustainability. Feed accounts for about half the cost in current high-volume fed mono-species aquaculture, mainly fish net pens or shrimp/fish ponds, yet most of this feed becomes waste. The resulting environmental impact and rising feed costs therefore hamper further growth of such farms. As in certain traditional polyculture schemes, plants can drastically reduce feed use and environmental impact of industrialized mariculture and at the same time add to its income. These nutrient-assimilating photoautotrophic plants use solar energy to turn nutrient-rich effluents into profitable resources. Plants counteract the environmental effects of the heterotrophic fed fish and shrimp and restore water quality. Today's integrated intensive aquaculture approaches, developed from traditional extensive polyculture, integrate the culture of fish or shrimp with vegetables, microalgae, shellfish and/or seaweeds. Integrated mariculture can take place in coastal waters or in ponds and can be highly intensified. Today's technologies are well studied and documented. They are generic, modular and adaptable for several culture combinations of fish, shrimp, shellfish, abalone, sea urchin and several species of commercially important seaweeds and vegetables. A 1-ha land-based integrated seabream-shellfish-seaweed farm can produce 25 tons of fish, 50 tons of bivalves and 30 tons fresh weight of seaweeds annually. Another farm model can produce in 1 ha 55 tons of seabream or 92 tons of salmon, with 385 or 500 fresh weight of seaweed, respectively, without pollution. Preliminary calculations show a potential for high profitability with large integrated farms. Several freshwater integrated fish¡vegetable farms and a couple of modern fish-algae-shellfish/abalone integrated mariculture farms exist today, and several additional farms are planned. Three major international R&D projects promise to soon expand the horizons of the technology further. Therefore, modern integrated systems in general, and seaweed-based systems in particular, are bound to play a major role in the sustainable expansion of world aquaculture.
ABSTRACT The United States has a $16 billion seafood deficit that the U.S. Department of Commerce and states are attempting to close by legislative policies, encouraging expansion of aquaculture in the United States. One of these policies, the 2011 National Shellfish Initiative, recognizes the benefits to water quality of cultivation of bivalve shellfish aquaculture in addition to the provision of seafood product. More recently, research addressing these policies has resulted in approval of the use of harvested oysters as a nutrient best management practice in the Chesapeake Bay region. Also discussed, but not yet fully implemented, is the inclusion of oyster growers in nutrient credit trading programs where economic compensation is provided to oyster growers for the nutrient removal ecosystem service that their oysters provide. This study used field sampling and a local-scale oyster production model to compare water quality, oyster production, and oyster associated nitrogen removal at two bottom and four water-column Maryland Chesapeake Bay oyster farms. Objectives were to highlight differences in water quality (i.e., oyster food), resultant differences in oyster production, and differences in estimated oyster-associated nutrient removal among farms. An avoided, or replacement, cost economic valuation analysis was performed to also compare the potential payment to the oyster growers for the nutrient removal service if they were included in a fully developed nutrient credit trading program. Production at the six sites varied from 1.78 to 25 metric tons of harvestable oysters acre–1 y–1. Oyster filtration–related N removal was estimated to be at a range of 28–457 kg N acre–1 y–1. The potential economic value of the total N removed by a farm was estimated to be at a range of $0.56 × 103–$12,446 × 103 y–1 among farm sites, depending on the alternative management measure used to assign the value.
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