RESUMEN
Seaweed cultivation can inhibit the occurrence of red tides. However, how seaweed aquaculture interactions with harmful algal blooms will be affected by the increasing occurrence and intensity of marine heatwaves (MHWs) is unknown. In this study, we run both monoculture and coculture systems to investigate the effects of a simulated heatwave on the competition of the economically important macroalga Gracilariopsis lemaneiformis against the harmful bloom diatom Skeletonema costatum. Coculture with G. lemaneiformis led to a growth decrease in S. costatum. Growth and photosynthetic activity (Fv/Fm) of G. lemaneiformis was greatly reduced by the heatwave treatment, and did not recover even after one week. Growth and photosynthetic activity of S. costatum was also reduced by the heatwave in coculture, but returned to normal during the recovery period. S. costatum also responded to the stressful environment by forming aggregates. Metabolomic analysis suggests that the negative effects on S. costatum were related to an allelochemical release from G. lemaneiformis. These findings show that MHWs may enhance the competitive advantages of S. costatum against G. lemaneiformis, leading to more severe harmful algal blooms in future extreme weather scenarios.
Asunto(s)
Diatomeas , Floraciones de Algas Nocivas , Algas Marinas , Diatomeas/fisiología , Algas Marinas/fisiología , Calor Extremo , Acuicultura , Gracilaria/fisiología , FotosíntesisRESUMEN
Blooms of microalgal red tides and macroalgae (e.g., green and golden tides caused by Ulva and Sargassum) have caused widespread problems around China in recent years, but there is uncertainty around what triggers these blooms and how they interact. Here, we use 30 years of monitoring data to help answer these questions, focusing on the four main species of microalgae Prorocentrum donghaiense, Karenia mikimotoi, Noctiluca scintillans, and Skeletonema costatum) associated with red tides in the region. The frequency of red tides increased from 1991 to 2003 and then decreased until 2020, with S. costatum red tides exhibiting the highest rate of decrease. Green tides started to occur around China in 1999 and the frequency of green tides has since been on the increase. Golden tides were first reported to occur around China in 2012. The frequency of macroalgal blooms has a negative linear relationship with the frequency and coverage of red tides around China, and a positive correlation with total nitrogen and phosphorus loads as well as with atmospheric CO2 and sea surface temperature (SST). Increased outbreaks of macroalgal blooms are very likely due to worsening levels of eutrophication, combined with rising CO2 and SST, which contribute to the reduced frequency of red tides. The increasing grazing rate of microzooplankton also results in the decline in areas affected by red tides. This study shows a clear shift of algal blooms from microalgae to macroalgae around China over the past 30 years driven by the combination of eutrophication, climate change, and grazing stress, indicating a fundamental change in coastal systems in the region.
Asunto(s)
Dinoflagelados , Microalgas , Algas Marinas , Cambio Climático , Dióxido de Carbono , Eutrofización , ChinaRESUMEN
Perfluoroalkyl substance (PFAS) existed ubiquitously in the environment and could be ingested unconsciously with food which posed a disease risk to human health. Swordtip squid (Uroteuthis edulis) is one of the most popular and highly consumed seafood worldwide, with wide distribution and abundant biomass. Therefore, it is of great importance to the health of the public by reducing the health risks of squid consumption while preserving the benefits of squid to humans. In this study, the PFAS and fatty acids in squids were tested from the southeast coastal regions of China, a major habitat for squids. Relative higher concentrations of PFAS in squid were found in the subtropical zone of southern China (mean: 15.90 ng/g·dw) compared to those of the temperate zone of northern China (mean: 11.77 ng/g·dw). The digestive system had high tissue/muscle ratio (TMR) values, and the pattern of TMR among the same carbon-chain PFAS was similar. Cooking methods have a significant contribution to eliminating PFAS (in squids). PFAS were transferred from squids to other mediums after cooking, so juice and oil should be poured out to minimize PFAS exposure into body. The result showed that squids can be regarded as a healthy food by health benefits associated with fatty acids. Estimated daily intake (EDI) had the highest level in Korea via consuming squids through cooking processes compared with other countries. Based on the assessment of the hazard ratios (HRs), there was a high exposure risk of perfluoropentanoic acid (PFPeA) via taking squids for human health. This research provided the theoretical guidance of aquatic product processing in improving nutrition and reducing harmful substances.
Asunto(s)
Ácidos Alcanesulfónicos , Fluorocarburos , Contaminantes Químicos del Agua , Animales , Humanos , Monitoreo del Ambiente/métodos , Decapodiformes , Alimentos Marinos , Ácidos Grasos , Culinaria , Nutrientes , Fluorocarburos/análisis , Ácidos Alcanesulfónicos/análisis , Contaminantes Químicos del Agua/análisisRESUMEN
China is responsible for the biggest shellfish and macroalgae production in the world. In this study, comprehensive methods were used to assess the CO2 release and sequestration by maricultured shellfish and macroalgae in China. Through considering CaCO3 production and CO2 release coefficient (Φ, moles of CO2 released per mole of CaCO3 formed) in different waters, we find that cultured shellfish released 0.741 ± 0.008 Tg C yr-1 through calcification based on the data of 2016-2020. In addition to calcification, maricultured shellfish released 0.580 ± 0.004 Tg C yr-1 by respiration. Meanwhile, shellfish sequestered 0.145 ± 0.001 and 0.0387 ± 0.0004 Tg C yr-1 organic carbon in sediments and shells, respectively. Therefore, the net released CO2 by maricultured shellfish was 1.136 ± 0.011 Tg C yr-1, which is about four times higher than that maricultured macroalgae could sequester (0.280 ± 0.010 Tg C yr-1). To achieve carbon neutrality within the mariculture system, shellfish culture may need to be restricted and meanwhile the expansion of macroalgae cultivation should be carried out. The mean carbon sequestration rate of seven kinds of macroalgae was 174 ± 6 g m-2 yr-1 while some cultivated macroalgae had higher CO2 sequestration rates, e.g. 356 ± 24 g C m-2 yr-1 for Gracilariopsis lemaneiformis and 331 ± 17 g C m-2 yr-1 for Undaria pinnatifida. In scenario 0.5 (CCUS (Carbon Capture, Utilization and Storage) sequesters 0.5 Gt CO2 per year), using macroalgae culture cannot achieve China's carbon neutrality by 2060 but in scenarios 1.0 and 1.5 (CCUS sequesters 1.0 and 1.5 Gt CO2 per year, respectively) it is feasible to achieve carbon neutrality using some macroalgae species with high carbon sequestration rates. This study provides important insights into how to develop mariculture in the context of carbon-neutrality and climate change mitigation.
Asunto(s)
Carbono , Algas Marinas , Carbono/análisis , Cambio Climático , Dióxido de Carbono/análisis , Secuestro de Carbono , Condiciones Sociales , ChinaRESUMEN
The ubiquitous distribution of perfluoroalkyl substances (PFASs) poses a threat to the health of aquatic organisms and humans. Bullfrogs are considered a popular aquatic food product in South China, providing high protein and tasty cuisine; however bullfrogs have been shown to contain significant concentrations of PFASs. However, the risk-benefit ratios of PFASs and nutrient contents in cooked bullfrogs are not well understood. PFASs and nutrients were investigated in raw and cooked specimens of cultured and wild bullfrogs in this study. Novel PFASs showed higher detection levels and accumulation in wild bullfrogs than in cultured bullfrogs. Potential factors such as fat and fatty acid ratio affected PFASs accumulation in different tissues and by different cooking methods of bullfrogs. All cooking methods can reduce PFASs in edible tissues while significantly enhancing the nutritive value index (NVI) compared to raw bullfrogs. Steaming was the most effective way to reduce PFASs (rate of reduction was over 66%) and resulted in a lower risk of contributing to arteriosclerosis than other cooking methods assessed by atherogenicity index (AI) values. Cultured bullfrogs instead of wild bullfrogs were recommended for human consumption, and steaming was regarded as a better cooking method in terms of risk-benefit concerns. Overall, this work provides quantitative analysis of cooking methods that alter PFASs and nutrients in bullfrogs.
Asunto(s)
Ácidos Alcanesulfónicos , Fluorocarburos , Contaminantes Químicos del Agua , Humanos , Animales , Rana catesbeiana , Fluorocarburos/toxicidad , Fluorocarburos/análisis , Alimentos , Nutrientes/análisis , Culinaria , China , Contaminantes Químicos del Agua/análisis , Ácidos Alcanesulfónicos/análisis , Monitoreo del AmbienteRESUMEN
Carbon, nitrogen, phosphorus and oxygen (CNPO) are essential biogenic elements, driving life activities in marine environments. However, the integrated research of fish and seaweed culture on the fluxes of CNPO is scarce. To bridge the research gap, the contribution of mariculture of fish and seaweeds to the fluxes of CNPO in two important mariculture provinces, Fujian and Guangdong, in China, was investigated for the first time. Data from published literature and this study were integrated to calculate the CNPO fluxes using relative formulas. CNP release and O2 loss caused by fish mariculture increased with year (2003-2020) and reached 185.55 ± 3.18 Gg C, 35.92 ± 0.51 Gg N, 7.27 ± 0.24 Gg P and 644.18 ± 11.05 Gg O2 for Fujian and 215.81 ± 2.51 Gg C, 41.77 ± 0.40 Gg N, 8.47 ± 0.19 Gg P and 749.23 ± 8.71 Gg O2 for Guangdong in 2020. The averaged P fluxes due to fish mariculture in Fujian and Guangdong during 2016-2020 are 2.2 folds of the Min River and 69 % of the Pearl River, respectively. CNP removal and O2 generation by seaweed culture in Fujian also increased with year (2003-2020) and reached 555.74 ± 16.45 Gg C, 58.44 ± 4.83 Gg N, 7.80 ± 1.41 Gg P and 1481.97 ± 43.86 Gg O2 in 2020. In contrast, seaweed culture in Guangdong resulted in maximal C (39.81 ± 1.43 Gg), N (4.33 ± 0.26 Gg) removal and O2 (106.15 ± 3.82 Gg) release in 2013 and maximal P (0.41 ± 0.03 Gg) removal in 2019. The averaged N and P fluxes due to seaweed culture in Fujian during 2016-2020 are 69 % and 2.4 folds of the Min River, respectively. The different mariculture structure leads to a net CNP sink in Fujian but a net CNP source in Guangdong. The net CNP source may lead to seawater acidification, eutrophication and deoxygenation in coastal areas. These findings supply solid data for adjusting mariculture structure to achieve CNPO neutrality within mariculture.