Integrated multi-trophic aquaculture (IMTA) in Sanggou Bay, China

The present study critically analyses peer-reviewed literature addressing the potential of halophytes to remediate nutrient-rich effluents from marine and coastal aquaculture, as well as the potential for their economic valorization, from human consumption to an untapped source of valuable secondary metabolites with pharmaceutical potential. The growing body of evidence discussed in this review supports the perspective that halophytes can become a new source of nutrition and other high-value compounds and be easily incorporated into saltwater-based integrated multi-trophic aquaculture (IMTA) systems. In this context, halophytes act as extractors of dissolved inorganic nutrients, primarily nitrogen and phosphate, usually wasted in marine aquaculture farms. Phytoremediation using halophytes has been proven to be an efficient solution, and several ways exist to couple this practice with land-based marine aquaculture systems, namely through constructed wetlands and aquaponics. Focusing research on ecosystem-based approaches to aquaculture production will provide valuable data for producers and policy makers in order to improve decision making towards a sustainable development of this economic sector. Ecointensification of aquaculture through IMTA will potentially increase the overall productivity and resilience of the sector, and halophytes, in particular, are on the verge of becoming key players for the diversification and promotion of land-based IMTA. This work specifically documents the uncharted potential of Halimione portulacoides, an important halophyte in European salt marsh ecosystems, as a new extractive species for IMTA.

Section: Introductionmentioning

confidence: 99%

Unravelling the potential of halophytes for marine integrated multi-trophic aquaculture (IMTA)— a perspective on performance, opportunities and challenges

Custódio¹,

Villasante²,

Cremades³

et al. 2017

“…This placement requires a very specific design, such as the square cages used in British Columbia (Canada), where the bivalve extractive species can be located right beside the finfish cage, potentially benefiting from the additional organic matter (Weldrick & Jelinski 2016). Another alternative arrangement that could benefit IMTA is the spatial design developed in some Chinese bays, such as Sanggou Bay, in which most of the available area is occupied by finfish, shellfish and seaweed farms (Fang et al 2016 and references therein). However, this placement or spatial arrangement is not usually practical for logistical reasons in most of the farms elsewhere.…”

Section: Fluxes Of Matter In Imta Sitesmentioning

confidence: 99%

Vertical particle fluxes dominate integrated multi‑trophic aquaculture (IMTA) sites: implications for shellfish-finfish synergy

Filgueira¹,

Guyondet²,

Reid³

et al. 2017

Maximizing the mitigation potential of open-water finfish−shellfish integrated multi-trophic aquaculture (IMTA) farms is complex in terms of co-locating the trophic components. Both the dispersal of finfish aquaculture wastes and biological processes are highly influenced by water circulation. Consequently, the evaluation of shellfish−finfish synergy requires a combined study of biological and physical processes, which can be achieved by the implementation and coupling of mathematical models. A highly configurable mathematical model was developed that can be applied at the apparent spatial scale of IMTA sites. The model tracks different components of the seston, including feed wastes, fish faeces, shellfish faeces, natural detritus and phytoplankton. Based on the characterization of these fluxes, a hypothetical IMTA site was used to explore different spatial arrangements for evaluating finfish−shellfish farm mitigation efficiency. The site was modelled following a factorial design, which tested 2 levels of background seston concentrations, 3 farm designs, 2 hydrodynamic conditions and 2 levels of aquaculture intensity. The model predicts that mitigation efficiency is highly dependent on the background environmental conditions, obtaining maximum mitigation under oligotrophic conditions that stimulate shellfish filtration activity. The dominance of vertical fluxes of particulate matter triggered by the high settling velocity of finfish aquaculture wastes suggests that suspended shellfish aquaculture cannot significantly reduce organic loading of the seabed. Consequently, this suggests that waste mitigation at IMTA sites should be best achieved by placing organic extractive species (e.g. deposit feeders) on the seabed directly beneath finfish cages rather than in suspension in the water column.

“…In most coastal waters, shellfish and seaweed are co-cultured, using suspended longlines as the main cultivation method. In fact, they usually dominate an entire bay, such as in Sanggou Bay (Fang et al 2016) and in Daya Bay (Yu et al 2014) where this study was conducted.…”

Section: Introductionmentioning

confidence: 99%

Interactive effects of oyster and seaweed on seawater dissolved inorganic carbon systems: implications for integrated multi-trophic aquaculture

Han¹,

Shi²,

Qi³

et al. 2017

We examined the separate effect of Portuguese oyster Crassostrea angulata and the interactive effects of oyster and red seaweed Gracilaria lemaneiformis on seawater dissolved inorganic carbon (DIC) systems and the air−sea CO 2 flux (F CO2 ) in Daya Bay, southern China. Respiration and calcification rates of oysters were measured and the effects of oyster aquaculture on marine DIC systems were evaluated. The interactive effects on seawater DIC and air−sea F CO2 were examined using mesocosms containing oyster and seaweed assemblages. Results showed populations of C. angulata cultured in Daya Bay sequestered ca. 258 g C m −2 yr −1 for shell formation, whereas the CO 2 released due to respiration and calcification was 349 and 153 g C m −2 yr −1 , respectively. This indicates that oyster cultivation in Daya Bay is a CO 2 generator, favoring the escape of CO 2 into the atmosphere. DIC, HCO 3 − and CO 2 concentrations and the partial pressure of CO 2 in oyster−seaweed co-cultured mesocosms were significantly lower than the oyster monoculture mesocosm. These results indicated that G. lemaneiformis effectively absorbs the CO 2 released by oysters. The negative values of air−sea F CO2 in the co-culture groups represent a CO 2 sink from the atmosphere to the sea. These results demonstrated that there could be an interspecies mutual benefit for both C. angulata and G. lemaneiformis in the integrated culture system. Considering that photosynthesis of seaweed is carbon limited, we suggest that the 2 species are co-cultured at a ratio of ca. 4:1 (based on fresh weight) for efficient utilization of DIC in seawater by G. lemaneiformis, and further to increase the ocean CO 2 sink.