Bivalves are increasingly being recognized as sustainable food sources that provide substantial ecosystem services; however, the debate regarding their role as either carbon sources or sinks remains unresolved. This study introduced a novel methodology for the comprehensive assessment of the physiological dynamics of the Manila clam Ruditapes philippinarum, utilizing in situ and continuous-flow experiments. Building upon these empirical findings, we developed a bioenergetic model grounded in Dynamic Energy Budget (DEB) theory. The model incorporates primary food sources, including phytoplankton and detritus, while addressing crucial physiological processes such as ingestion, respiration, calcification and biodeposition. This integrative framework was employed to examine the dynamics of the carbon budgets of clams over a 365-day period, highlighting their role in carbon storage within the ecosystem. Notably, seasonal variations had a significant influence on the clams' physiological performance, including rates of clearance, ingestion and oxygen consumption. According to the model simulation results, each clam stored approximately 973 mg of carbon annually, of which 296 mg was dedicated to shell formation and 677 mg was contributed through biodeposition. This study enhances our understanding of the ecological contributions of bivalves and emphasizes their crucial role in carbon cycling within mariculture environments.

Ocean acidification (OA) is predicted to threaten marine bivalves, casting them as passive victims of changing carbonate chemistry. Contributing to a revised understanding, we identified a conserved mechanism for acid-base regulation that supports intracellular resilience. Using the Manila clam Ruditapes philippinarum as a model, this study demonstrated that intracellular pH (pHi) homeostasis under elevated pCO2 was maintained through cytosolic carbonic anhydrase (CAc)-mediated H+ efflux. A causal link was established by combining in vivo scanning ion-selective electrode technique (SIET) with RNA interference (RNAi), where RpCAc knockdown suppressed H+ efflux and compromised pHi. A coordinated regulatory network involving CAc, soluble adenylyl cyclase (sAC), and Na+/K+-ATPase (NKA) was synergistically upregulated, suggesting an evolved adaptive pathway. Dynamic Energy Budget (DEB) modeling, calibrated with experimental data, revealed that this cellular compensation carries a high energetic cost, leading to a significant reallocation of resources: shell growth was maintained, but somatic growth was severely suppressed. These results elucidate a conserved cytoprotective mechanism that enables short-term tolerance of OA at a substantial somatic cost, redefining resilience to include energetic trade-offs.

The intertidal zone experiences significant fluctuations in temperature and pH, posing significant challenges to marine organisms. Perinereis aibuhitensis, a eurythermal and euryhaline polychaete inhabiting estuaries, where pH is often lower than in the open ocean and further reduced within sediments, has likely evolved robust adaptations to such stresses. We investigated its behavioral, physiological, and metabolic responses under combined temperature (15°C, 20°C, 25°C) and seawater acidification (pH 5.5, 6.7, 8.0) conditions. P. aibuhitensis exhibited stable behavioral performance and metabolic homeostasis under control conditions (20°C, pH 8.0). It maintained burrowing activity and activated physiological and metabolic regulation at pH 6.7. However, its motion significantly declined with failed behavioral regulation under pH 5.5: radial undulation duration decreased by 97.63% and pumping volume by 97.97%. Energy was reallocated toward antioxidant defense and maintenance of basic physiological functions, reflected in downregulation of the γ-aminobutyric acid (GABA) metabolic pathway alongside upregulation of ABC transporter and arachidonic acid metabolism. At 25°C, combined warming and acidification disrupted energy allocation under pH 5.5. This disruption was accompanied by enhanced motion, which further constrained energy allocation, leading to significant oxidative damage (MDA content increased by 94.54%) and concurrently impairing tryptophan metabolism, glycerophospholipid metabolism, and ABC transporter function, with the entire cascade ultimately collapsing its adaptive mechanisms. This demonstrates that severe acidification, especially under warming, compromises bioturbation and metabolic stability in P. aibuhitensis, with potential negative impacts on polychaete communities and their vital ecological functions in intertidal ecosystems. Our findings provide critical insights for predicting climate change impacts on marine infauna.

This study systematically evaluated the sediment remediation and nutrient cycling functions of sea cucumber (Apostichopus japonicus) across three size classes (small: 52.1 ± 4.22 g; medium: 88.5 ± 13.61 g; large: 119.24 ± 7.38 g) in a novel oyster (Crassostrea gigas) -kelp (Saccharina japonica) -sea cucumber integrated multi-trophic aquaculture (IMTA) system. Integrated methodologies included stable isotope analysis (δ13C, δ15N), carbon and nitrogen budget determinations, and monitoring of nutrient fluxes across sediment-water interface. Results sea cucumbers preferentially consumed aquaculture-derived biodeposits, which constituted the major component of surface sediments and possessed high nutritional value (>60% dietary contribution), primarily including oyster feces and suspended particulate matter (SPM) from oyster and kelp monoculture areas. Carbon and nitrogen budgets revealed a distinct size-dependent "low assimilation-high egestion" metabolic strategy, with small individuals exhibiting highest mass-specific oxygen consumption (0.013 mg O2·g-1·h-1), peak ammonia excretion (0.725 μg NH4+-N·g-1·h-1), and superior net removal efficiencies for sedimentary organic carbon (53.1%) and nitrogen (34.6%). Bioturbation significantly enhanced nitrogen and phosphorus cycling, jointly modulated by body size and temperature: at temperatures <20.97 ± 0.38 °C, large individuals drove dissolved inorganic nitrogen (DIN) and PO43--P fluxes 1.9 and 1.3 times higher, respectively, than small counterparts. Sustained exposure above this thermal threshold suppressed behavioral and metabolic activity across all size classes, progressively eliminating DIN and PO43--P flux differentials between bioturbation treatments and controls. Thermal stress additionally altered benthic dissolved oxygen dynamics and nutrient speciation patterns. These findings will provide a theoretical basis for optimizing bioregulatory strategies in multi-trophic aquaculture systems.

The quantity and quality of plankton are generally affected by the characteristics of the water, and water environmental conditions are also considered key factors affecting the growth of hydrobionts. Consequently, an investigation was conducted into the environmental parameters, and the characteristics of plankton in the sampling sites of Mazuao, Sanggou Bay, and Guazichang, as well as their impact on the growth parameters of oysters. The results indicated that the average water temperature in the Mazuao area was higher than that in Sanggou Bay and Guazichang, while the salinity was lower. The dissolved oxygen and pH values in all three areas met the criteria for mariculture water quality. The diversity and abundance of plankton exhibited seasonal variations, with the total abundance being higher in June (summer) and reaching the minimum in December (winter) in all three sea areas. The phytoplankton species composition in the three aquaculture areas was of the ‘Diatom-Pyrrophyta’ type, and diatoms dominate in plankton. Redundancy analysis (RDA) showed that plankton abundance has the highest correlation with water temperature, salinity, dissolved oxygen and pH. Notably, the Mazuao area had the highest average total abundance of phytoplankton throughout the year. Overall, oysters could obtain better growth advantages in the Mazuao area. RDA indicated that water temperature and plankton abundance in the Mazuao area were dominant factors affecting the growth parameters of oysters. Understanding these relationships is crucial for effective coastal ecosystem management and ensuring the long-term sustainability of aquaculture industries.

China,a major global shellfish aquaculture country,had a national shellfish aquaculture output of 16,659,000 t in 2024,of which marine aquaculture accounted for 98.81％.As the main farmed species,oysters have an annual output of 6,671,200 t,accounting for 40.52％of the total production of marine shellfish farming.Due to the over-expansion of certain traditional aquaculture areas,the ecological carrying capacity has been exceeded and the phytoplankton biomass available for oyster feeding has been reduced,resulting in lower fattening,quality,and market price,and higher mortality rates;therefore,exploring new oyster fattening sites and methods has become integral in solving the current problems in the industry.To investigate the feasibility of Crassostrea gigas pond fattening,a self-developed culture device of oyster ponds was used to enhance the water exchange around C.gigas by using the flow generated by the natural wind disturbance on the surface of the pond to increase the bait delivery efficiency to provide sufficient bait for the C.gigas,and to try to fertilize the diploid C.gigas,which have poor fattening degree,cultured in the sea area in the shrimp and crab ponds.We fattened diploid C.gigas with poor fattening in marine culture in shrimp and crab culture ponds.From November 2023 to May 2024(the experiment was suspended during the winter freezing period),we visited the experimental ponds every 20 days to collect samples and used the WTW multi-parameter water quality analysis to measure the water temperature,salinity,pH,and dissolved oxygen.We used a water collector to collect 2 L of water samples from each of the five points at the four corners of the ponds(5-10 m from the shore)and the center of the ponds and then stored them in water sample bottles.Next,referring to the Code of Practice for Marine Surveys,the water samples were fixed with 5％formaldehyde solution on site and transported back to the laboratory to measure nutrient salt,chlorophyll a,and particulate organic matter(POM)contents.Three sizes(S,M,L)of C.gigas were set up to determine the growth and physiological indices,with average wet weights of(54.86±3.26)g,(83.81±3.94)g,and(127.46±8.64)g,respectively,and were cultured in three mixed groups in oyster pond culture devices.For the physiological indices,eight replicates and one control were established for each specification treatment group,and a flow-through device comprising a buffer box,flow-through tank,and rectangular plastic box was used for feeding physiology and respiratory metabolism measurements.During the experimental period,a grapple-type mud collector was used to collect pond sediment underneath and around the aquaculture devices at the aquaculture site,artificial feed,suspended particles,and feces of C.gigas,which were used to determine the sediment of aquaculture ponds.The pond sediment was collected in different months.No significant differences(P＞0.05)were noted in water temperature,salinity,pH,dissolved oxygen content,chlorophyll a,and POM content of the culture ponds in different months;however,there were significant differences(P＜0.05)in PO43--P,NO2--N,NO3--N,and NH4+-N in the culture ponds in different months.The differences in fecundity of the three oyster sizes in the same month were not significant(P＞0.05);however,the differences in the water filtration,droppings,oxygen consumption,and ammonia discharge rates were all significant(P＜0.05),whereas those in fecundity of the same sizes of oysters in different months were significant(P＜0.05).The energy balance equation showed that all three oyster sizes used the most energy for growth in May,with the highest percentage of 48.64％;after 6 months of cultivation,the fattening degree of oysters increased by 31.7％,and the fastest growth rate of large-size oysters was 55.1％.Comparing the same batch of oysters from ponds and the sea area in the same period of time showed that the survival and fattening degree of oysters from pond culture were higher than those of oyster cultivation in the sea area(P＜0.05).An analysis of organic matter sources in the pond sediments showed that the further away from the aquaculture unit,the higher the contribution of suspended particles,whereas the opposite was true for artificial feed and feces.This study showed that C.gigas are more effective for fattening in marine shrimp and crab ponds,and it is recommended to begin the pond fattening production in autumn from mid-September to mid-October,and in spring from mid-March to mid-May,and to select C.gigas with larger sizes,so that the desired degree of fattening can be reached after 1-2 months.

Shellfish and macroalgae are usually known as environmental remediation species in aquaculture systems. However, the environmental issues are frequently found in shellfish and macroalgae large scale monoculture areas. Although shellfish and macroalgae IMTA might mitigate adverse effects of monoculture, the relationships among cultured organisms, plankton and environmental factors are unclear. This study evaluated the ecological impacts of Crassostrea gigas and Gracilaria lemaneiformis monoculture versus integrated multi-trophic aquaculture (IMTA) systems in Sanggou Bay, China, through a 5-day in-situ enclosure experiment. We assessed the nutrient levels, inorganic carbon system, plankton abundance, and Chl-a concentration under different aquaculture modes. Results revealed that oyster monoculture increased PO43--P levels, DIN concentrations and elevated CO₂ levels, exacerbating acidification risks. In contrast, IMTA systems with oyster-to-macroalgae ratios of 1:1 and 4:2 reduced PO43--P levels by 75 %, optimized DIN removal, and mitigated CO₂ accumulation. Moreover, oyster monoculture promoted pico-phytoplankton dominance by suppressing competitors (micro-/nano-phytoplankton) and predators (zooplankton), a trend reversed in IMTA systems where macroalgae limited pico-phytoplankton proliferation. Besides, Chl-a declined across all treatments. The in-situ enclosure experiment provided realistic insights into species-environment interactions, overcoming laboratory limitations of oversimplified systems. These findings underscore that IMTA ratios of 1:1 and 4:2 enhance nutrient cycling, stabilize carbonate system, and reduce eutrophication risks. This study advances sustainable aquaculture practices by demonstrating how optimized species ratios balance productivity and environmental health, offering actionable strategies for coastal management to mitigate ecological degradation in semi-enclosed bays.

Bivalves like the Pacific oyster (Crassostrea gigas) are vital protein sources and key aquaculture species in Chinese coasts. In order to find the better oyster lines and their suitable farming sea area, this study evaluated chlorophyll-a (Chl-a), particulate organic matter (POM), and nutrient concentrations (PO₄³⁻-P, NO₂⁻-N, NO₃⁻-N, NH₄⁺-N) across three aquaculture areas (Mazuao, Sanggou Bay, Guazichang) from June 2021 to June 2022, while comparing growth, metabolism, and feeding physiology of diploids, Haida No.1, and triploids C. gigas. Mazuao exhibited the highest Chl-a and POM levels but greater nutrient fluctuations, whereas Sanggou Bay had lower levels of Chl-a and POM. Overall, compared to diploids, Haida No.1 and triploids showed significant growth advantages in different sea areas. Logistic modeling and Genotype and Genotype × Environment biplot (GGE biplot) analysis recommended Haida No.1 for Mazuao due to its lower oxygen consumption, higher filtration rates, and optimal O:N ratios. At the same time, it is recommended to cultivate triploids in Sanggou Bay and Guazichang. This study provides data support for the selection of C. gigas lines for cultivation in different sea areas and offers theoretical guidance for explaining the growth differences among the three C. gigas lines.

To clarify interactions among bivalves, macroalgae, and water column in the bivalve-macroalgae polyculture system, in-situ mesocosm cultivation was conducted for 24 h in both summer and winter. These experiments assessed seasonal variations in CO2 and components of dissolved inorganic carbon (DIC), nitrogen (DIN), and phosphorus (DIP) under three modes: monoculture of three sizes of oysters (Crassostrea gigas) (OA group), monoculture of kelp (Saccharina latissima) (KA group), and polyculture of oysters and kelp (KO group) at fixed wet weight ratio of 800: 200 g. The results revealed the OA group functioned as a CO2 source in both summer and winter, with summer increase rates of DIC, DIN, and DIP by oysters much higher than in winter and decreasing with larger oyster size. Pearson correlation analysis indicated a negative correlation between soft tissue dry weight of oysters and concentrations of NO2--N and NH4+-N. While, the KA group functioned as a CO2 sink, with winter decrease rates of DIC, DIN, and DIP by kelp being 14.24, 3.16, and 5.54 times greater than in summer, respectively. In the KO groups, oyster size and seasonal factors significantly affected water parameters, including pH, dissolved oxygen (DO), pCO(2), and various DIC, DIN, and DIP components (P < 0.05) and the system released DIC, DIN, and DIP in summer while absorbing them in winter. Subtraction calculations indicated that the culturing water in KO groups absorbed CO2, DIC, DIN, and DIP during both seasons, suggesting a synergistic bioremediation effect between phytoplankton and macroalgae at an appropriate cultivation ratio.

Calcium carbonate skeleton fragments and powder of marine organisms are important components of marine sediments. They might play positive ecological functions in the benthic ecosystem. The present study found that the addition of ultrafine oyster shell powder (UOSP) could raise sediment pH from 7.11 to 7.78 while notably reducing H₂S, Pb and Mn by 55.27 %, 83.92 % and 76.17 %, respectively. Additionally, UOSP further led to the alteration of bacterial community structure. RDA results revealed that pH significantly affected bacterial keystone species (P < 0.05), which occupied crucial positions in promoting the continuous carbon‑sulfur cycle, suggesting that the addition of UOSP sustained the core function of the benthic microecosystem. The wet weights of benthic animal bivalve and polychaete increased by 18.43 % and 13.98 %, respectively, due to the improved health and sedimentary environment. The present study confirms that the natural shell powder provides significant ecological benefits to the benthic ecosystem. The application of UOSP in sediment restoration is viable.

This study investigates the optimal integration of shellfish (Mytilus edulis) and algae (Gracilaria lemaneiformis) aquaculture in semi-enclosed bay of Sanggou Bay, China, to enhance bioremediation and water quality. An enclosure experiment spanning five days was carried out to assess the impact of six mussel-to-algae wet weight ratios (3:5, 3:10, 6:5, 6:10, 9:5, 9:10) on dissolved oxygen (DO), pH, nutrient levels, inorganic carbon dynamics, plankton abundance, and chlorophyll-a (Chl-a) concentration in the integrated multi-trophic aquaculture (IMTA) system. The in-situ enclosure experiment provided realistic insights into species-environment interactions, overcoming laboratory limitations of oversimplified systems. Results revealed diurnal DO and pH fluctuations driven by mussel respiration and algal photosynthesis. Higher G. lemaneiformis proportions (3:10) elevated DO and pH (>8.7), reduced dissolved inorganic carbon (DIC) and pCO₂, but induced phosphorus limitation (PO₄3--P < 0.2 μmol/L), triggering pico-phytoplankton proliferation. Conversely, higher mussel ratios (9:5) lowered pH (7.7) and increased DIC, risking acidification. The ratios of 3:5, 6:5, 6:10, and 9:10 balanced ecological impacts, maintaining pH 7.8-8.5 (China's seawater standards), reducing nutrients (PO₄3--P removal: 51.3-62.0 %), and suppressing phytoplankton miniaturization. These ratios optimized nutrient levels, minimized eutrophication risks, and stabilized carbonate system, demonstrating their efficacy in sustainable IMTA. These findings highlight the importance of balancing mussel and algae proportions in IMTA systems to achieve sustainable aquaculture practices with minimal environmental impact. Moreover, this study optimizes the ratio of M. edulis and G. lemaneiformis to balance the stability of aquaculture water environment parameters, offering actionable strategies for coastal management to mitigate ecological degradation in semi-enclosed bays.

A five-day in situ experiment was conducted in plastic enclosures to investigate the effects of different densities of the mussel Mytilus edulis, and sampling time on water variables, and phytoplankton community structure in Sanggou Bay (Shandong, China). The tested mussel densities were low (LD300: 300 g/m3), medium (MD600: 600 g/m3), high (HD900: 900 g/m3), and sampling times were at 6:00 and 17:00 h. The water variables analyzed as indicators were pH, dissolved oxygen, nutrients, carbonate system, pCO2, and chlorophyll-a (Chl-a). The results showed that density and sampling time had highly significant effects on all water parameters and phytoplankton abundance, except for dissolved oxygen (P<0.01). At the same sampling time, pH, c[CO32-] and Chl-a concentrations in the water column of LD300 treatment were much higher than those of MD600 and HD900 treatments, while c[HCO3-], c[CO2] and pCO2 were significantly lower than those of MD600 and HD900 treatments (P<0.01). Phosphate was the main limiting nutrient for phytoplankton growth. Chl-a concentrations increased and then decreased significantly in LD300 and MD600 treatments, while it diminished continuously in HD900 treatment. The higher M. edulis density showed higher correlation with picophytoplankton abundance and Chl-a concentrations. Not only the phytoplankton structure was affected, but also the condition index of the HD900 treatment was significantly reduced (P<0.05). The present study showed LD300 and MD600 treatments significantly promoted the growth of picophytoplankton. The selective filtration of M. edulis for microphytoplankton and nanophytoplankton were much higher than those for picophytoplankton. The combined decrease in competitors (micro- and nanophytoplankton) led to a substantial increase of picophytoplankton abundance in shellfish farming areas. The interactions between mussel and phytoplankton significantly affected the water environment. However, well designed integrated shellfish and algae aquaculture might mitigate the adverse impacts.

This study aimed to investigate the autolysis pathway and reveal the autolysis mechanisms of Perinereis aibuhitensis. Morphological structure, oxidative stress and autolysis-related enzyme activities and relative genes expression at different stages of autolysis (0, 24, 48, 72, 96 and 120 h) at 20 °C, and in different temperatures (10, 15, 20 and 25 °C) at 72 h were determined. Furthermore, we sequenced the second-generation transcriptomes of the P. aibuhitensis at different stages of autolysis and verified the authenticity of the transcriptomic data by real-time fluorescence quantitative PCR (RT-PCR). Results showed that there was obvious autolysis phenomenon after 24 h, and the effect of autolysis on muscle fiber and body tissue structure was the most obvious at 72 h. At 10 °C, the internal tissue and muscle fiber structure of P. aibuhitensis remained relatively complete and arranged regularly. With the increase of temperature, the muscle fibers of P. aibuhitensis dissolved and broke. The overall content of MDA showed a downward trend and and reached the minimum at 72 h. CAT activity decreased significantly and reached its lowest value at 96 h. GSH, GST and GPx decreased first and then increased with different time periods of autolysis. MMP-9 maintained a high level at 24 h and the content was the highest at 48 h. The contents of MDA and GSH in P. aibuhitensis showed a fluctuating trend with the increase of temperature. The activity of GPx and the content of MMP 9 in P. aibuhitensis increased significantly with the increase of temperature (P < 0.05). A total of 78,653 Unigenes were obtained after sequencing, including 1,495 differentially expressed genes in the P0h and P72hDS groups, and 1995 differentially expressed genes (DEGs) in the P0h and P72hUD groups. In the P0h vs P72hDS group, the DEGs were mainly concentrated in ECM-receptor interaction, Apoptosis-multiple species, and Arachidonic acid metabolism pathways. And in the P0h vs P72hUD group, the DEGs were mainly concentrated in ECM-receptor interaction, Polyketide sugar unit biosynthesis, and Arachidonic acid metabolism pathway. Fourteen DEGs were screened and subjected to RT-PCR detection, which confirmed the accuracy of the transcriptome results and also suggested that these genes were closely related to autolysis in P. aibuhitensis. All these results provide a basis for the study of the autolysis process and related genes in P. aibuhitensis, and also contributes to the study of the autolysis mechanism in other marine animals.

Perinereis aibuhitensis is an essential bait for prompting ovarian development and sexual maturation in aqua -culture shrimp broodstock. It is common for shrimp to become infected with pathogens by ingesting feed con-taining potential viruses. To prevent P. aibuhitensis being live feeds for shrimp broodstock from transmitting pathogens, we evaluated the disinfection effect of peroxymonosulfate (PMS) against covert mortality nodavirus (CMNV) by carrying out Oryzias melastigma (marine medaka) challenge assay and testing CMNV-exposed P. aibuhitensis eggs. In the marine medaka injected with PMS (15 and 20 ppm (ppm))-inactivated CMNV, no CMNV was detected at 6 and 12 days post-infection (d.p.i.) by using quantitative reverse transcription PCR (RT-qPCR). As well, no CMNV probe positive signal and pathological signs caused by CMNV in these marine medaka were present in situ hybridization (ISH) and histopathology assays. CMNV was not detected in the nectochaeta larvae originated from CMNV-exposed P. aibuhitensis eggs treated with PMS (5, 10, 15 and 20 ppm) for 1 min. In addition, nereids treated with 15 ppm PMS for 1 min had higher hatchability. Even at low concentrations of PMS-treated eggs, the hatchability was higher than that of the no-PMS-treated group, and no adverse effects on larval development after hatching were observed. Our study showed that disinfection of CMNV-exposed eggs by PMS is feasible. Disinfection of P. aibuhitensis eggs with PMS could reduce the risk of transmission of CMNV. Within acceptable limits for hatchery spawn losses, the recommended disinfection dose of PMS is 15 ppm for 1 min. This study laid the foundation for the culture of specific pathogen-free P. aibuhitensis and to provide biological baits with no pathogenic risk to farmed shrimp.

Aquaculture, especially of non-native species and translocated domestic species, is a greatly encouraged way of relieving the conflicts between food and economic demand and resource depletion. We herein summarized the introduction history of non-native fish for aquacultural use in China, including 105 species introduced from abroad and 61 species translocated domestically across river basins, which has brought great economic benefits but high ecological risks. Of these, one-fourth have successfully established wild populations in natural waters and 15% have successfully invaded. We presented specific examples of seven aquaculture species/taxa and three aquarium species/taxa to explain their outcomes. The notable economic benefits, complex species composition and strain selection of tilapias, carps and sturgeons may together facilitate their invasion, and result in fish diversity decline, genetic pollution, and loss of ecosystem service. We specifically reviewed invasion cases in lakes and reservoirs and found that lakes in western China and reservoirs made by major hydroprojects are hotspots for non-native species, and this has led to the disappearance of endemic species and changes to the original faunal composition. The escaped non-native fish introduced via aquaculture has changed the original fish biogeography, resulting in the loss of assemblage uniqueness and causing faunal homogeneity. China has achieved significant progress in completing the Aichi Targets by improving the legal system and strengthening conservational actions on controlling non-native species. Further actions, especially on risk assessment and management of non-native species are expected for a healthy outlook for the aquaculture industry of China.

China is a major aquaculture country, with both the world´s largest aquaculture production and area, especially oyster aquaculture which accounts for 80% of the global production. However, its ascent has had numerous negative implications, requiring the development of more environmentally friendly aquaculture methods. The ecological farming model is gradually being acknowledged and encouraged as it is the result of in-depth investigations of marine ecosystems. "Integrated Multi-trophic Aquaculture" is a well-known environmentally friendly aquaculture model. The application effects have been outstanding, as it boosts high output per unit area, improves the marine environment, and improves material utilization. Filter-feeding shellfish are raised at levels that create considerable biodeposition. Particulate matter is transferred from the upper to the lower layers of the water body. Organic matter accumulates on the seafloor in the form of biological sediments, which badly influences the substrate environment, including releasing ammonia nitrogen, increasing dissolved oxygen consumption, and altering seabed biodiversity. Previous research suggests sea cucumbers absorb large amounts of organic matter-rich sediments, reducing the nutrient load caused by coastal shellfish and fish aquaculture. Therefore, a novel sustainable farming model based on the principle of multi-trophic integrated farming could be developed by using sedimentary sea cucumbers to feed on the biological sediments produced by filter-feeding shellfish. The purpose of this study was to investigate the possibility of an oyster-sea cucumber raft integrated culture. Sea cucumbers were stocked in oyster breeding cages. A raft-style integrated oyster-sea cucumber culture was attempted to improve the breeding method. This method allows oyster biological sediments to be utilized in situ, reducing oyster breeding density and maintaining economic benefits. This comparative culture experiment of integrated oyster (Crassostrea gigas)-sea cucumber (Apostichopus japonicus) raft culture utilized Sanggou Bay and Guazichang as representative oyster farming locations. We stocked C. gigas in the odd-numbered layers and A. japonicus in the even-numbered layers of the oyster cages in polyculture. Even-numbered layers had three levels of chassis: common aquaculture plate, holeless aquaculture plate, and holeless aquaculture plate with non-knot nets. The aquaculture plate was the first variable in the experiment. The stocking density of A. japonicus in each of the even-numbered layers were separated into three levels, 1, 2, and 4 ind./plate. The second variable in the experiment was stocking density of sea cucumbers. The experiment was simultaneously conducted at both sea locations. Therefore, the experimental design consisted of a three-factor and three-level experiment with a total of 18 treatment groups. During the experiment, we examined to content of: chlorophyll a, particulate organic matter, PO43–-P, NO2–-N, NO3–-N, and NH4+-N in both sea locations. The survival rate, growth performance, and condition of C. gigas and A. japonicus were compared. There was no significant difference in the contents of chlorophyll a or particle organic matter between the two marine areas (P > 0.05). There were significant differences in the four nutrient salt contents between the two locations (P < 0.05). There were no significant differences in the individual oyster weight or condition between the two locations (P > 0.05). Only the low-stocking density sea cucumbers grew, with individual weights over 25% higher than that of the high-density individuals. Individual sea cucumber weights and survival rates in the low density treatment groups were considerably higher than those in the high density treatment groups (P < 0.05). The performance of the holeless aquaculture plate considerably exceeded the common treatment group (P < 0.05). The holeless aquaculture plates with sea cucumbers at a density of 1 ind./plate achieved the highest results in this study. The chlorophyll in the sea area of Sanggou Bay remained mostly unchanged in this experiment. However, the chlorophyll in the water region of Guazichang reduced when compared with that of previous data. With the recent rapid growth in the oyster industry in Rushan City, the oyster output may have reached or possibly exceeds the area´s aquaculture capacity. We advise the oyster breeding density in the Rushan sea area to be reduced to lower the breeding risk for farmers while also promoting the breeding industry´s long-term viability. In this experiment, there was no significant difference in oyster growth across the treatment groups, indicating that the integrated oyster-sea cucumber raft culture mode can lower oyster density and reduce environmental impacts. Simultaneously, breeding high-value sea cucumbers compensates for the loss of breeding income induced by the lower oyster breeding density. When compared to bottom-seeded sea cucumbers, this raft cage mode has a higher level of safety and ease of harvest. This method can be used to replenish oyster growing zones with a high density of oysters to boost the aquaculture industry´s health and long-term development.

The Ria de Aveiro is an important coastal lagoon for wildlife in Portugal, where the production of bivalves reaches approximately 2700 tons annually. However, the illegal overfishing of bivalves is frequent in this lagoon, which causes critical changes in the ecosystem. In this study, using a developed food-web model (Ecopath model), the ecological carrying capacity (ECC) and maximum sustained yield (MSY) of the Manila clam, Ruditapes philippinarum were estimated, and the effects of further increases in clam biomass on other species were investigated. The results showed that 1) the current biomass and legal catch of R. philippinarum do not yet exceed the ECC (172.40 tons km-2) or the MSY (86.20 tons km-2 year-1) in Ria de Aveiro; 2) the harvested Manila clams of the MSY represent removing from the ecosystem ∼ 581 tons carbon (C) and ∼83 tons nitrogen (N) annually, with substantial ecological and economic implications; and 3) a further increase in the biomass levels of this species may cause the ecotrophic efficiency of other groups to become unrealistic, potentially leading to decreases in ecosystem transfer efficiency, biodiversity and health. The results here are expected to guide the sustainable development and management of bivalve aquaculture in Ria de Aveiro and the protection of the local environment.

Rapana venosa is primarily distributed in the Yellow Sea and Bohai Sea of China, Japan, Korea, and Russia. In the natural sea area, the adult R. Venosa mostly inhabits the sand-mud bottom or the rocky bottom of the low intertidal zone up to 20 meters deep, and the young R. Venosa mostly inhabits the rocks near the coastal line. Its habitats are generally occupied by many other bivalves, such as Crassostrea gigas, Mactra chinensis, and Ruditapes philippinarum. The R. venosa is a large carnivorous Mollusca that mainly feeds on bivalves and other animal carcasses. R. venosa is often classified as an enemy of bivalve farming, but they can also be used to control fouling organisms, and it has potential for application in aquaculture and ocean engineering.In recent years, there have been some reports on the feeding selectivity of R. venosa, the effects of feed, temperature, and individual specifications on feeding, the effects of feed types, specifications, feeding amount, and breeding density on the survival and growth, the feeding preferences to different bivalves and the feeding cycle before and after reproduction. These studies mainly explored the effects of temperature, density, feed types, and specifications on its growth and development. The main purpose of these studies was to select suitable feed types and specifications for the temporary culture and breeding of R. venosa, to improve its growth and development speed, and increase economic benefits under artificial breeding conditions. However, the feeding selection and behavior process of R. venosa under natural conditions are not clear, and the feeding selection of R. venosa to C. gigas, Mytilus edulis and other fouling organisms was not clear under the environmental conditions of multiple bait bivalve habitats. Therefore, in this study, four kinds of bivalves (fixed type, attached type and buried type) were used as bait bivalves to understand the feeding selection. C. gigas and M. edulis are common fouling organisms in the habitat of R. venosa, while M. veneriformis and R. philippinarum are widely distributed in the habitat of R. venosa. The study attempts to simulate the habitat of R. venosa and different types of bait bivalves in the natural environment, to study its preference for bait bivalves species and feeding specifications, to compare and analyze the differences in feeding rates of different specifications of R. venosa, and further study its feeding rhythm and feeding process and to provide data reference for the feasibility of using R. venosa to control C. gigas, M. edulis and other bivalves fouling organisms, and improve the feeding habits of R. venosa.To achieve these objectives, three specifications of M. veneriformis, R. philippinarum, C. gigas, and M. edulis live baits were placed in the aquarium by simulating the natural environment. The feeding number, feeding weight, feeding specifications, feeding time, and feeding behavior process of three specifications of R. venosa to different baits were recorded. The experimental results showed that R. venosa fed on all four bivalves. The number and weight of R. venosa that fed on M. veneriformis with different specifications were significantly higher than those that fed on other bivalves (P < 0.05), and the feeding index was more than 50%, indicating its appetite. R. venosa fed normally on C. gigas and R. philippinarum, and only a small population of R. venosa fed on M. edulis with large specifications. In terms of the selection of feeding specifications, three specifications of R. venosa preferred large M. veneriformis and small C. gigas (P < 0.05). The feeding rate of the large specification R. venosa was 7.15%, which was significantly lower than that of the other two specifications (small specification, 10.98%; medium specification, 9.64%). Under the experimental conditions, the feeding cycle of R. venosa was apparent, feeding activities were carried out every three days, and the feeding time was 20:00–24:00 at night. The feeding process can be divided into four stages: Unfed stage, search stage, feeding stage, and feeding end. During the feeding process, the R. venosa actively searched for bivalves, removed them from the sand and wrapped them with their proleg, secreted mucus, and smacked them from the shell gap. After sucking the mollusks decomposed by digestive juice, the R. venosa dived into the sand or attached to the aquarium wall. The results showed that under the experimental conditions, R. venosa had a feeding preference for the species and specifications of bait bivalves. R. venosa preferred to eat M. veneriformis and rarely consumed M. edulis. Moreover, its feeding behavior was nocturnal and exhibited periodicity, feeding activity happened every three days in the first half of the night.

为探究在南麂海域进行长牡蛎(Crassostrea gigas)筏式笼养的效果,本研究选用"海大系列"长牡蛎新品种(海大1号、海大2号和海大3号),在南麂海域马祖岙海区开展筏式笼养实验.按月份进行周年跟踪测定该海域的环境因子和长牡蛎个体的生长指标.研究表明:南麂海域周年水温变化范围为10.50～28.12 ℃,盐度平均为29.14,pH平均为7.93;叶绿素a含量为0.42～6.64 μg/L,颗粒有机物含量为2.41～11.32 mg/L;海水中氮磷比范围为2.51～39.06.实验结束时,三个品种中,海大1号和海大3号长牡蛎的湿质量显著高于海大2号(P＜0.05),壳高无显著性差异(P＞0.05),湿质量的特定生长率均在1月最高,肥满度在6月最高.三个品种的湿质量增加量均与水温、盐度和叶绿素a含量呈正相关关系(P＜0.05),与铵盐含量呈负相关关系(P＜0.05).Logistic模型对三个品种的湿质量变化曲线拟合效果最好.本研究结果表明,在南麂海域筏式笼养"海大系列"长牡蛎新品种具可行性,其中,海大1号长牡蛎新品种的养殖效果最好.

Biological burrowing behavior is an important driver shaping ecosystems that is being threatened by CO2-induced ocean acidification; however, the effects of ocean acidification on burrowing behavior and its neurological mechanism remain unclear. This study showed that elevated pCO2 significantly affected the burrowing behaviors of the Manila clam Ruditapes philippinarum, such as increased foot contraction, burrowing time, and intrabottom movement and decreased burrowing depth. Delving deeper into the mechanism, exposure to elevated pCO2 significantly decreased extracellular pH and increased [HCO3-]. Moreover, an indicator GABAA receptor, a neuroinhibitor for movement, was found to be closely associated with behavioral changes. In situ hybridization confirmed that the GABAA receptor was widely distributed in ganglia and foot muscles, and elevated pCO2 significantly increased the mRNA level and GABA concentration. However, the increase in GABAA receptor and its ligand did not suppress the foot movement, but rather sent "excitatory" signals for foot contraction. The destabilization of acid-base homeostasis was demonstrated to induce an increase in the reversal potential for GABAA receptor and an alteration in GABAA receptor function under elevated pCO2. This study revealed that elevated pCO2 affects the burrowing behavior of Manila clams by altering GABAA receptor function from inhibitory to excitatory.