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Special issue opening comments: Seaweed-based integrated mariculture
Aquaculture 252 (2006) 1 – 2 www.elsevier.com/locate/aqua-online
Editorial
Special issue opening comments: Seaweed-based integrated mariculture The current economic success of modern aquaculture relies on the fact that the industry does not have to internalize the costs of increasing nutrient loads to the environment where effluents are released. However, it is expected that increased awareness of the environmental impacts of aquaculture effluents on the environment will alter this situation. Soon, the industry will no doubt be compelled to treat their effluents prior to discharge into the surrounding environment. Integrating a seaweed cultivation system into fish or shrimp farms is likely to be one of the most cost effective and sustainable solutions available to producers. In a seminal review published in Aquaculture, Neori et al. (2004) described the background, the evolution and the state of the art of seaweed biofiltration in integrated mariculture. The authors concluded that these nutrient-scavenging systems are bound to play a major role in the sustainable growth of world aquaculture, specifically referring to the expected contributions of three major international aquaculture research and development projects. In this Special Issue we present contributions from one of these projects, the European Union project SEAPURA—Species Diversification and Improvement of Aquatic Production in Seaweeds Purifying Effluents from Integrated Fish Farms. The selected contributions found in this volume make up the major findings from the SEAPURA project (Bansemir et al.; Mata et al.; Matos et al.; Pang and Lüning; Schuenhoff et al.; Valente et al.), as well as the insights of several invited speakers to the international workshop “Production in Seaweeds Purifying Effluents from Marine Animal Holding Units” (Carmona et al.; Hernández et al.; Metaxa et al.; Pereira et al.), held in Faro, Portugal in November 2003, as a concluding act of SEAPURA. The rationale and the state of the art of integrated aquaculture are well established. Seaweeds can be used 0044-8486/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2005.12.004
to restore water quality being discharged from marine fish and shrimp aquaculture operations, reducing the environmental impact derived from the high load of nutrients contained in their effluents. The low nutrient, oxygen-rich effluent of a seaweed biofilter can be safely discharged to the environment, or even recirculated back to fishponds with putative positive effects on the fish health. Until present, the most commonly used biofilters have been green seaweeds from of the genus Ulva, and of the red species Gracilaria. Their cultivation is well established, but their market value is low. A principal goal of SEAPURA was to test and develop the cultivation of high-value seaweed species not used before in integrated aquaculture, and to improve tank-culture success for established seaweed species in order to reduce the undesirable effects of intensive fish mariculture. The production and biofiltration rates of selected species were investigated under different cultivation systems, environmental conditions and nutrient fluxes. The first contributions presented in this Special Issue focus the first objective of SEAPURA, the seaweed species diversification in integrated aquaculture systems. Schuenhoff et al. and Mata et al. establish the innovative tank cultivation of red filamentous seaweeds, namely the tetrasporophyte phase of Asparagopsis armata, Bonnemaisoniales. This was the most successful of the species tested, which revealed to be a better alternative to the commonly used seaweed biofilters. Its removal rate of total ammonia nitrogen doubled the values reported for Ulva species. Moreover, the tetrasporophyte of A. armata has a high potential of economic valorization as it concentrates halogenated organic metabolites. The production, extraction and use of halogenated compounds of the Bonnemaisoniales as antibiotics and fungicides, namely for skin cosmetics, were patented by members of the SEAPURA project (Lognone et al., 2003).
2
Editorial
The following contributions tackle essential issues to improvement of tank-culture success for established seaweed species, such as unwanted seaweed sporulation and control of the species life cycle (Pang and Lüning), optimization of production and biofiltration rates (Matos et al.) and the up-scale of cultivation systems (Hernández et al.). Pang and Lüning reveal environmental triggers of Palmaria palmata spore release and demonstrate that the species can be sustainably farmed year-round. Matos et al. show that a cascade system highly improved biofiltration of integrated aquaculture of the red seaweeds Chondrus crispus and Gracilaria bursa pastoris in a sea bass farm. The results of Hernández et al. on the upscale of the cultivation of Gracilaria longissima, encourage the establishment of large scale cultivation of this species in southern Europe. The two next contributions of Carmona et al. and Pereira et al. show that Porphyra species, particularly P. dioica, may also be good candidates for integrated aquaculture. Contributions revealing novel applications of the seaweed biomass produced in integrated aquaculture follow. Bansemir et al. reveals that 5 out of the 26 seaweed species cultivated in SEAPURA had strong antibacterial activity against fish pathogenic bacteria and thus can potentially be used to prevent disease among farmed fish. Valente et al. shows that the inclusion of Gracilaria bursa pastoris and Ulva rigida at up to 10% of the protein fraction of the fish diet can be a valuable alternative, with no adverse effects on the growth performance, nutrient utilization or body composition of fish. Finally, Metaxa et al. show that the use of seaweed biofilters in re-circulating aquaculture systems may provide an added benefit of improving fish health thereby reducing fish mortality. We trust that the work presented in this Special Issue contributes to the establishment of seaweed-based integrated mariculture, and aids in the successful implementation of integrated farms in developed countries. However, the future development of this
technology may depend on the level of legislation pressure on the aquaculture industry to purify farm effluents. If environmental legislation pressures remains low as it is in the present, no major developments will be expected unless a high profitability of seaweed biomass produced is demonstrated. Then, the selection of seaweed species that produce secondary metabolites with high economic value and the economic valorization of these products is essential. If legislation pressures increases, the biofiltration potential of the technology may become the primary goal. Then, the seaweed biomass produced may be regarded as a by-product that has to be disposed at low cost. In this case, more traditional, low value applications of the seaweed biomass produced, may be envisaged, for direct consumption by humans or animals or for the extraction of phycocolloids for example. The public image of the industry may also become an important factor. The fish/seaweed co-cultivation concept can improve the public image of fish farming, since it is based on the common sense approach of converting waste rather than discharging it with negative effects on the ecosystem. References Lognone, V., Patrick, D., Lunning, K., Santos, R., Mata, L., Bansemir, A., Schuenhoff, A., Lindequivist, U., 2003. Procedé de production a terre des algues rouges de la famille des Bonnemaisoniacées. Submission n° 0308717. Institut National de la Proprieté Industrielle, Paris, France. Neori, A., Chopin, T., Troell, M., Buschmann, A., Kraemer, G., Halling, C., Shpigel, M., Yarish, C., 2004. Integrated aquaculture: rationale, evolution and state of the art emphasizing seaweed biofiltration in modern mariculture. Aquaculture 231, 361–391.
Rui Santos Algae-Marine Ecology Research Group, Center of Marine Sciences of Algarve, University of Algarve, 8005-139 Faro, Portugal E-mail address: [email protected].
Editorial
Special issue opening comments: Seaweed-based integrated mariculture The current economic success of modern aquaculture relies on the fact that the industry does not have to internalize the costs of increasing nutrient loads to the environment where effluents are released. However, it is expected that increased awareness of the environmental impacts of aquaculture effluents on the environment will alter this situation. Soon, the industry will no doubt be compelled to treat their effluents prior to discharge into the surrounding environment. Integrating a seaweed cultivation system into fish or shrimp farms is likely to be one of the most cost effective and sustainable solutions available to producers. In a seminal review published in Aquaculture, Neori et al. (2004) described the background, the evolution and the state of the art of seaweed biofiltration in integrated mariculture. The authors concluded that these nutrient-scavenging systems are bound to play a major role in the sustainable growth of world aquaculture, specifically referring to the expected contributions of three major international aquaculture research and development projects. In this Special Issue we present contributions from one of these projects, the European Union project SEAPURA—Species Diversification and Improvement of Aquatic Production in Seaweeds Purifying Effluents from Integrated Fish Farms. The selected contributions found in this volume make up the major findings from the SEAPURA project (Bansemir et al.; Mata et al.; Matos et al.; Pang and Lüning; Schuenhoff et al.; Valente et al.), as well as the insights of several invited speakers to the international workshop “Production in Seaweeds Purifying Effluents from Marine Animal Holding Units” (Carmona et al.; Hernández et al.; Metaxa et al.; Pereira et al.), held in Faro, Portugal in November 2003, as a concluding act of SEAPURA. The rationale and the state of the art of integrated aquaculture are well established. Seaweeds can be used 0044-8486/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2005.12.004
to restore water quality being discharged from marine fish and shrimp aquaculture operations, reducing the environmental impact derived from the high load of nutrients contained in their effluents. The low nutrient, oxygen-rich effluent of a seaweed biofilter can be safely discharged to the environment, or even recirculated back to fishponds with putative positive effects on the fish health. Until present, the most commonly used biofilters have been green seaweeds from of the genus Ulva, and of the red species Gracilaria. Their cultivation is well established, but their market value is low. A principal goal of SEAPURA was to test and develop the cultivation of high-value seaweed species not used before in integrated aquaculture, and to improve tank-culture success for established seaweed species in order to reduce the undesirable effects of intensive fish mariculture. The production and biofiltration rates of selected species were investigated under different cultivation systems, environmental conditions and nutrient fluxes. The first contributions presented in this Special Issue focus the first objective of SEAPURA, the seaweed species diversification in integrated aquaculture systems. Schuenhoff et al. and Mata et al. establish the innovative tank cultivation of red filamentous seaweeds, namely the tetrasporophyte phase of Asparagopsis armata, Bonnemaisoniales. This was the most successful of the species tested, which revealed to be a better alternative to the commonly used seaweed biofilters. Its removal rate of total ammonia nitrogen doubled the values reported for Ulva species. Moreover, the tetrasporophyte of A. armata has a high potential of economic valorization as it concentrates halogenated organic metabolites. The production, extraction and use of halogenated compounds of the Bonnemaisoniales as antibiotics and fungicides, namely for skin cosmetics, were patented by members of the SEAPURA project (Lognone et al., 2003).
2
Editorial
The following contributions tackle essential issues to improvement of tank-culture success for established seaweed species, such as unwanted seaweed sporulation and control of the species life cycle (Pang and Lüning), optimization of production and biofiltration rates (Matos et al.) and the up-scale of cultivation systems (Hernández et al.). Pang and Lüning reveal environmental triggers of Palmaria palmata spore release and demonstrate that the species can be sustainably farmed year-round. Matos et al. show that a cascade system highly improved biofiltration of integrated aquaculture of the red seaweeds Chondrus crispus and Gracilaria bursa pastoris in a sea bass farm. The results of Hernández et al. on the upscale of the cultivation of Gracilaria longissima, encourage the establishment of large scale cultivation of this species in southern Europe. The two next contributions of Carmona et al. and Pereira et al. show that Porphyra species, particularly P. dioica, may also be good candidates for integrated aquaculture. Contributions revealing novel applications of the seaweed biomass produced in integrated aquaculture follow. Bansemir et al. reveals that 5 out of the 26 seaweed species cultivated in SEAPURA had strong antibacterial activity against fish pathogenic bacteria and thus can potentially be used to prevent disease among farmed fish. Valente et al. shows that the inclusion of Gracilaria bursa pastoris and Ulva rigida at up to 10% of the protein fraction of the fish diet can be a valuable alternative, with no adverse effects on the growth performance, nutrient utilization or body composition of fish. Finally, Metaxa et al. show that the use of seaweed biofilters in re-circulating aquaculture systems may provide an added benefit of improving fish health thereby reducing fish mortality. We trust that the work presented in this Special Issue contributes to the establishment of seaweed-based integrated mariculture, and aids in the successful implementation of integrated farms in developed countries. However, the future development of this
technology may depend on the level of legislation pressure on the aquaculture industry to purify farm effluents. If environmental legislation pressures remains low as it is in the present, no major developments will be expected unless a high profitability of seaweed biomass produced is demonstrated. Then, the selection of seaweed species that produce secondary metabolites with high economic value and the economic valorization of these products is essential. If legislation pressures increases, the biofiltration potential of the technology may become the primary goal. Then, the seaweed biomass produced may be regarded as a by-product that has to be disposed at low cost. In this case, more traditional, low value applications of the seaweed biomass produced, may be envisaged, for direct consumption by humans or animals or for the extraction of phycocolloids for example. The public image of the industry may also become an important factor. The fish/seaweed co-cultivation concept can improve the public image of fish farming, since it is based on the common sense approach of converting waste rather than discharging it with negative effects on the ecosystem. References Lognone, V., Patrick, D., Lunning, K., Santos, R., Mata, L., Bansemir, A., Schuenhoff, A., Lindequivist, U., 2003. Procedé de production a terre des algues rouges de la famille des Bonnemaisoniacées. Submission n° 0308717. Institut National de la Proprieté Industrielle, Paris, France. Neori, A., Chopin, T., Troell, M., Buschmann, A., Kraemer, G., Halling, C., Shpigel, M., Yarish, C., 2004. Integrated aquaculture: rationale, evolution and state of the art emphasizing seaweed biofiltration in modern mariculture. Aquaculture 231, 361–391.
Rui Santos Algae-Marine Ecology Research Group, Center of Marine Sciences of Algarve, University of Algarve, 8005-139 Faro, Portugal E-mail address: [email protected].