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Using the Modelling‐Ongrowing fish farms‐Monitoring B investigation system (MOM‐B), we discussed the effects of deep sea cage (DSC) and traditional sea cage (TSC) fish mariculture on benthic environments in the Yellow Sea, China. Macrofauna, and chemical and sensory parameters were evaluated at 10 field stations surrounding a traditional sea cage farm in 2016–2017 and 10 field stations surrounding a deep sea cage farm in 2018–2019. Benthic macrofauna were found in all samples, and biological parameters were universally rated acceptable or better. In spring and winter, the pH and redox potential values near the DSC farm were within the score 0, while in summer and autumn, values were within the score 1. In TSC farm, most scores were in the score 0 in spring and autumn and in the score 1 in summer. Chemical parameter results showed the DSC and TSC farms were all in condition 1, whereas the sensory parameters near the DSC farm were in condition 1, and the TSC farm in condition 2. Finally, the results demonstrate benthic environments near the DSC farm were better than those near the TSC farm. MOM‐B system provides a practical environmental assessment tool that is simple, cheap and easy to implement and can be performed by moderately trained personnel. [ABSTRACT FROM AUTHOR]

A portion of carbon produced from shellfish and kelp cultivation is buried in sedimentary environment, and mariculture carbon sequestration potential is an important part of marine carbon sink and has attracted worldwide attention. Total organic carbon (TOC), total nitrogen (TN) and their stable isotopes (δ13C and δ15N), as well as the mass distribution of these size-fractionated particles were determined in order to study the distribution and sources of TOC in Sanggou Bay. Results showed that sediment organic matter has complex sources from kelp (30.4 %), marine phytoplankton (25.6 %), shellfish (23.7 %), terrestrial input (20.3 %), and mariculture activities of shellfish and kelp was the major component in surface sediment. Approximately 44–69 % of TOC was associated with the 16–32 μm fraction. Low δ13C (−22.1 to −15.1‰) and high δ15N (5.0–5.7‰) were observed in fine particles (<16 μm), indicating relatively high contribution of marine phytoplankton and mariculture derived organic carbon. On the contrary, relatively higher δ13C (−20.2 to −9.2‰) and lower values δ15N (−4.7 to 5.2‰) in coarse particles (>32 μm) suggested that sedimentary organic carbon might be influenced by some additional sources from terrestrial input or seaweed. The mass distribution, δ13C and δ15N of size-fractionated particles in sediments indicated that sediment was obviously redistributed under the condition of mariculture, and further suggested that mariculture derived organic matter have modified the distribution and sources of sedimentary organic matter. This study provided great insight into distribution and source of sedimentary organic carbon from the perspective of size-fractionated particles in mariculture area. • The mass composition of the size-fractionated particles was determined to access the impact of mariculture on sediment. • The sources of sedimentary organic carbon were quantitative analyzed according to isotopic values and C/N ratio. • We innovative studied the effect of mariculture on organic carbon source from the perspective of particle size spectrum. [ABSTRACT FROM AUTHOR]

Reducing CO2 emissions and increasing carbon sinks are basic approaches to achieve carbon neutralization in China. China is the largest mariculture country in the world. China's mariculture industry is dominated by non-fed culture type and characterized by rich species, diverse nutrition levels, and advanced farming technology. Therefore, mariculture has huge potential for the development of ocean negative carbon emissions (ONCE). However, the ONCE process of bivalves and seaweed farming is complicated, and the scientific principles, process, mechanisms, monitoring and evaluating methods, and approaches of increasing carbon sink are gradually being recognized and yet to be resolved. This study discusses the research progress of fishery carbon sink, existing problems and possible impact of global climate change on ONCE of mariculture. It then proposes technological approachs and policy suggestions to implement ONCE, which include expanding mariculture space and increaseing unit yield, green development of mariculture based on carrying capacity regulatory regime, integrated multi-trophic aquaculture, blue carbon engineering of ocean ranching, and marine artificial upwelling. [ABSTRACT FROM AUTHOR]

China is the global leader in mariculture production. Increasing sequestered marine carbon (also known as blue carbon) via mariculture activities is a promising approach for mitigating climate change and promoting the development of a low-carbon economy. Mariculture blue carbon is also considered an important component of China's 'sea granary'. In addition to shellfish and macroalgae yields, which represent carbon removed from mariculture environment, blue carbon also includes other important components, which have been largely neglected in the past, such as the carbon transformed by microbes, dissolved organic carbon (mainly referred to as recalcitrant dissolved organic carbon), and sedimentary particulate carbon. Hence, from different aspects, a comprehensive study on the formation processes and mechanisms of carbon sequestration is of great significance for comprehensively unveiling the carbon sequestration capability in coastal mariculture environment, which will contribute to the sustainable development of the fishery economy and construction of an ecological civilization. Moreover, it may add significant economic benefits to the future carbon-trading market. [ABSTRACT FROM AUTHOR]

The growth and survival of the scallop Chlamys farreri exposed to different initial densities were evaluated in culture systems from inshore and offshore areas of Sungo Bay, China, from May 2007 to March 2008. Water quality data (e.g. temperature, salinity, current speed, chlorophyll a and total particulate material) were measured concurrently. The C. farreri reached the market size after 10 months of cultivation. Average survival rates for the same initial densities were lower in the inshore area than those in the offshore area. Survival rates also were inversely proportional to the initial densities. Scallops in offshore area with initial densities of 20 and 30 individuals per disc resulted in significantly greater shell heights, soft tissue weights and muscle weight compared with the other experimental groups. Tissue weight increased rapidly from May to September. However, scallops in offshore area had a second growth peak during October to November. Scallops in the offshore area had higher growth and survival rates, which may be attributed to high water current speed resulting in increased food supplies. Results indicate that the scallop C. farreri has an aquaculture potential in offshore cultivation systems. [ABSTRACT FROM AUTHOR]

A biophysical model was used to study bivalve-seaweed integrated culture in Sungo Bay, a typical intensive longline mariculture site in China. Based on this model, the observed variations in pelagic variables and growth of cultivated species were reasonably reproduced. The results showed that the nutrients carried by water exchange were more than sufficient to support the growth of kelp, while the growth of oysters was mainly supported by the local accumulation of phytoplankton, and the majority of scallop's food was supplied by water exchange. A reduction of water exchange would lead to a decrease in the quality of scallops, whereas the growth of oysters would be promoted. Considering the interactions among species and areas, the growth potential of mariculture in Sungo Bay was evaluated. From an area-scale perspective, mariculture in specific areas has certain growth potential. From a bay-scale perspective, the seeding density in the bay should be reduced. In addition, a precise assessment of growth potential should be a tradeoff between seeding density and water exchange. Although further improvement is needed, this model is an effective tool to assist with the management of spatially heterogeneous aquaculture systems, and similar approaches can be applied to other aquaculture sites. • A biophysical model was used to study the growth potential of mariculture. • Interactions among species and areas were considered. • The effects of water exchange and phytoplankton were highlighted. • The model provides a tool for managing spatially heterogeneous culture systems. [ABSTRACT FROM AUTHOR]

The rapid development of offshore mariculture brings the environmental challenges and requests for carrying capacity-based management strategy. A pollutant diffusion model coupled hydrodynamic model and 3-D Lagrangian particle-tracking model was implemented to evaluate the environmental carrying capacity of the sea cage in off-coast farming in the Yellow Sea, China. The water level data on August 1–31, 2018 and concentration of nutrient in surface sediment in May, August, November 2018, and January 2019 were used to verify the model. The results showed that the model is reliable to capture the main characteristics of the environmental variables in the study area. Total annual sea bass output were around 335 t per year (t a−1), the nitrogen and phosphorus emissions of about 30.95 t a−1, 5.90 t a−1, respectively. Total nitrogen in the sediment accumulated to 691.4 mg kg−1 (0.056 kg m−2) on average after a year simulation. The selection of culture sites, especially the current velocity, and settling velocity of the particles play significant roles on the fish output and the diffusion of pollutants. According to the acceptable standards of sediment nitrogenous nutrient, the sea bass culture density can be expanded to 1.46 times the present level to reach the environmental carrying capacity. Feed formulations and feeding regimes are important factors in determining the carrying capacity that need to be strategically improved with developing technology. The model provides a useful tool to sustainable environmental management of sea cage culture. • Coupled hydrodynamic and Lagrangian particle-tracking model for pollutant tracking. • Successfully assessed carrying capacity in the sea cage mariculture ranching of China. • Sea bass culture density can be expanded to 1.46 times the present level. [ABSTRACT FROM AUTHOR]

Two sediment cores (S1 and S2 from shellfish and kelp cultivation areas, respectively) were collected from the Sanggou Bay maricultural area for the analysis of biogenic silica (BSi), an ideal proxy for the reconstruction of diatom density. The results show that prior to the advent of mariculture, the maximum diatom density in the two cores were observed in the 1880s before the first industrial revolution, and the maximum densities were 6500 × 10 4 ind m −3 and 5300 × 10 4 ind m −3 for S1 and S2, respectively. The diatom density was primarily affected by natural factors, such as the sea surface temperature (SST), the East Asian Winter Monsoon Index (EAWM), and the wild shellfish feeding pressure. The diatom density was affected by different cultivation methods and maricultural density during the maricultivation period. The diatom density decreased to 2800 × 10 4 ind m −3 in the shellfish cultivation area (S1) in 1996, and the diatom density was only 3600 × 10 4 ind m −3 in the kelp cultivation area (S2). Subsequently, a shellfish-kelp polyculture approach was implemented and diatom density started to continuously increase. The total diatom densities in S1 and S2 were restored to 3700 × 10 4 ind m −3 and 4200 × 10 4 ind m −3 in 2006, respectively. Nonetheless, the total diatom density in core S1 was only 55% of the density in the 1880s. This observation indicates that additional efforts are required to promote modifications to improve the cultivation environment and establish an environmentally-friendly cultivation model. [ABSTRACT FROM AUTHOR]