The environmental analysis and site selection of mussel and large yellow croaker aquaculture areas based on high resolution remote sensing

Mussel aquaculture and large yellow croaker aquaculture areas and their environmental characteristics in Zhoushan were analyzed using satellite data and in-situ surveys.A new two-step remote sensing method was proposed and applied to determine the basic environmental characteristics of the best mussel and large yellow croaker aquaculture areas.This methodology includes the first step of extraction of the location distribution and the second step of the extraction of internal environmental factors.The fishery ranching index(FRI1,FRI2)was established to extract the mussel and the large yellow croaker aquaculture area in Zhoushan,using Gaofen-1(GF-1)and Gaofen-6(GF-6)satellite data with a special resolution of 2 m.In the second step,the environmental factors such as sea surface temperature(SST),chlorophyll a(Chl-a)concentration,current and tide,suspended sediment concentration(SSC)in mussel aquaculture area and large yellow croaker aquaculture area were extracted and analyzed in detail.The results show the following three points.(1)For the extraction of the mussel aquaculture area,FRI1 and FRI2 are complementary,and the combination of FRI1 and FRI2 is suitable to extract the mussel aquaculture area.As for the large yellow croaker aquaculture area extraction,FRI2 is suitable.(2)Mussel aquaculture and the large yellow croaker aquaculture area in Zhoushan are mainly located on the side near the islands that are away from the eastern open waters.The water environment factor template suitable for mussel and large yellow croaker aquaculture was determined.(3)This two-step remote sensing method can be used for the preliminary screening of potential site selection for the mussels and large yellow croaker aquaculture area in the future.the fishery ranching index(FRI1,FRI2)in this paper can be applied to extract the mussel and large yellow croaker aquaculture areas in coastal waters around the world.

Impacts of Integrated Multi-Trophic Aquaculture on Phytoplankton in Sanggou Bay

Integrated multi-trophic aquaculture(IMTA)has been considered as an ecofriendly culture system providing a potential solution to environmental risks caused by intensive monoculture system.However,the impact of IMTA on phytoplankton remains unclear.In this study,the spatial and temporal variations of phytoplankton in Sanggou Bay were investigated seasonally based on 21 sampling sites covering three cultivation zones(bivalve zone,IMTA zone,and kelp zone)and one control zone(without aquatic cultivation).In total,128 phytoplankton species,with diatoms and dinoflagellates as the dominant groups,were obtained across the whole year,and the mean Shannon diversity index(H')and species richness(SR)were determined as 1.39 and 9.39,respectively.The maximum chlorophyll a(Chl-a)(6.32μg L^(-1))and plankton diversity(H'of 1.97)occurred in summer and autumn,respectively.Compared to other zones,the bivalve zone displayed significantly higher Chl-a and lower H'in majority of time.Pairwise PERMANOVA analysis indicated that the phytoplankton assemblage in the bivalve zone was significantly different with the control and kelp zones,while the IMTA zone maintained close to other three zones.Based on generalized additive models,temperature,NO_(2)^(-)-N,N/P ratio,SiO_(3)^(2-)-Si,and salinity were determined as the key factors underlying Chl-a and phytoplankton diversity.Addi-tionally,the results of redundancy analysis further indicated that the phytoplankton assemblage in the bivalve zone is positively re-lated with nutrients such as NO_(3)^(-)-N and NH_(4)^(+)-N as well as water depth,while the phytoplankton assemblages in the kelp,control,and IMTA zones are associated with NO_(2)^(-)-N,SiO_(3)^(2-)-Si,and salinity.Taken all observations into consideration together,it can be inferred that IMTA can effectively reduce Chl-a level compared to bivalve monoculture by reducing the nutrients.However,the SR,H’,and species composition of phytoplankton are primarily determined by local environment factors such as temperature,water depth,salinity and SiO_(3)^(2-)-Si.

Effect of length-width ratio of rounded rectangle aquaculture tank in dual-diagonal-inlet layout on hydrodynamics

To adapt to the change of aquaculture workshop site,optimize the shape of aquaculture tanks and improve the utilization rate of breeding space,it is necessary to determine the appropriate length width ratio parameters of aquaculture tanks.In this paper,computational fluid dynamics(CFD)technology is adopted to study the flow field performance of aquaculture tanks with different L/B ratios(L:the length;B:the width,of aquaculture tank)and different jet direction conditions(lengthways jet and widthways jet).A three-dimensional numerical calculation model of turbulence in rounded rectangle aquaculture tanks in dual-diagonal-inlet layout was established.Jet directions are arranged lengthways and widthways,and the water flow velocity,resistance coefficient change,vorticity,etc.are analyzed under two working conditions.Results show that the flow field performance in aquaculture tank decreases with the increase of the L/B ratio.The flow field performed well when L/B was 1.0-1.3,sharply dropped at 1.4-1.6,and poor at 1.7-1.9.The results provided a theoretical basis for the design and optimization in flow field performance of the industrialized circulating aquaculture tanks.

Distribution and sources of sedimentary organic matter in different aquaculture areas of northeastern Zhanjiang Bay using stable carbon and nitrogen isotopes

Zhanjiang Bay is a major aquaculture area in China with many types of mariculture products(such as oysters,fish,and shrimp).The culture area and shrimp output in Zhanjiang Bay are ranked first in China.We investigated the total organic carbon(TOC),total nitrogen(TN),TOC/TN ratio,and stable isotopes(δ^(13)C and δ^(15)N) of the fish and shrimp feed,fish and shrimp feces,and sedimentary organic matter(SOM) in and around different aquaculture areas of northeastern Zhanjiang B ay to study the impact of aquaculture activities on SOM.The average TOC contents of fish and shrimp feed were 39.20%±0.91% and 39.29%±0.21%,respectively.The average TOC content in the surface sediments of the oyster culture area,the mixed(fish and shrimp) culture area,and the cage fish farm area were 0.66%,0.88%±0.10%,and 0.58%±0.19%,respectively,which may indicate that mixed culture had a greater impact on SOM.The relatively high TOC and TN contents and relatively low TOC/TN ratios,and δ^(15)N values in the upper layer of the core sediment in the mixed culture area could also support the significant influence of mixed culture.The average δ^(13)C and δ^(15)N values of fish and shrimp feed were -20.6‰±2.2‰ and 1.8‰±1.2‰,respectively,which were different from the isotopic values of SOM in the study area.δ^(13)C and δ^(15)N values for SOM in different aquaculture areas were different from those of nearby reference stations,probably reflecting the influence of aquaculture.The δ^(13)C and δ^(15)N values in the oyster culture area(-25.9‰ and6.0‰,respectively) seemed to have reduced δ^(13)C and enriched δ^(15)N relative to those of the reference station(-24.6‰ and 5.8‰,respectively).This may reflect the influence of organic matter on oyster culture.The δ^(15)N value of the station in the mixed culture area(7.1‰±0.4‰) seemed to be relatively enriched in δ^(15)N relative to that of the reference station(6.6‰).Sedimentation and the subsequent degradation of organic matter from mixed cultures may have contributed to this phenomenon.The surface sediment at the cage fish farm area seemed to be affected by fish feces and primary production based on the indication of δ^(13)C and δ^(15)N values.The sediment core at the mixed culture region(NS6) had lower TOC/TN ratios and more positive δ^(13)C and δ^(15)N values than the sediment core at the oyster culture area,suggesting a higher proportionate contribution of marine organic matter in the mixed culture area.In summary,oyster culture,mixed culture,and cage fish culture in northeastern Zhanjiang Bay had a certain degree of impact on SOM,and mixed culture had more significant influences on SOM based on the high TOC contents and the significant vertical variations of TOC/TN ratio and δ^(15)N value in the sediment of this area.This study provides new insights into the impact of aquaculture activities on SOM content.

Numerical simulation of inlet placement on sewage characteristics in the rounded square aquaculture tank with single inlet

To improve the self-cleaning ability of aquaculture tank and the efficiency of circulating water,physical and numerical experiments were conducted on the influence of inlet structure on sewage discharge in a rounded square aquaculture tank with a single inlet.Based on the physical model of the tank,analysis of how inlet structure adjustment affects sewage discharge efficiency and flow field characteristics was conducted to provide suitable flow field conditions for sinkable solid particle discharge.In addition,an internal flow field simulation was conducted using the RNG k-εturbulence model in hydraulic drive mode.Then a solid-fluid multiphase model was created to investigate how the inlet structure affects sewage collection in the rounded square aquaculture tank with single inlet and outlet.The finding revealed that the impact of inlet structure is considerably affecting sewage collection.The conditions of C/B=0.07-0.11(the ratio of horizontal distance between the center of the inlet pipe and the tank wall(C)to length of the tank(B))andα=25°(αis the angle between the direction of the jet and the tangential direction of the arc angle)resulted in optimal sewage collection,which is similar to the flow field experiment in the rounded square aquaculture tank with single inlet and outlet.An excellent correlation was revealed between sewage collection and fluid circulation stability in the aquaculture tank.The present study provided a reference for design and optimization of circulating aquaculture tanks in aquaculture industry.

A Novel YOLOv5s-Based Lightweight Model for Detecting Fish’s Unhealthy States in Aquaculture

Real-time detection of unhealthy fish remains a significant challenge in intensive recirculating aquaculture.Early recognition of unhealthy fish and the implementation of appropriate treatment measures are crucial for preventing the spread of diseases and minimizing economic losses.To address this issue,an improved algorithm based on the You Only Look Once v5s(YOLOv5s)lightweight model has been proposed.This enhanced model incorporates a faster lightweight structure and a new Convolutional Block Attention Module(CBAM)to achieve high recognition accuracy.Furthermore,the model introduces theα-SIoU loss function,which combines theα-Intersection over Union(α-IoU)and Shape Intersection over Union(SIoU)loss functions,thereby improving the accuracy of bounding box regression and object recognition.The average precision of the improved model reaches 94.2%for detecting unhealthy fish,representing increases of 11.3%,9.9%,9.7%,2.5%,and 2.1%compared to YOLOv3-tiny,YOLOv4,YOLOv5s,GhostNet-YOLOv5,and YOLOv7,respectively.Additionally,the improved model positively impacts hardware efficiency,reducing requirements for memory size by 59.0%,67.0%,63.0%,44.7%,and 55.6%in comparison to the five models mentioned above.The experimental results underscore the effectiveness of these approaches in addressing the challenges associated with fish health detection,and highlighting their significant practical implications and broad application prospects.

High-quality Development Path of Graduate Education in Aquaculture Discipline:A Case Study of Guangdong Ocean University

Aquaculture is a discipline system that focuses on exploring the growth,development,reproduction,aquaculture,and resources of aquatic animals and plants,and their complex relationships.Under the tide of the"high-quality development"strategy,the aquaculture discipline is also facing new opportunities and challenges for transformation,upgrading,and deepening development.Therefore,exploring and practicing an effective path for the high-quality development of graduate education in aquaculture is not only the key to promoting the transformation of graduate education in aquaculture from scale expansion to quality improvement,but also has immeasurable value for implementing the strategy on developing a quality workforce and the strategy of scientific and technological powerhouse.The high-quality development of graduate education in aquaculture can be promoted from the following aspects:optimizing and improving the construction of the graduate education system,focusing on enhancing the quality of high-level talent cultivation,strengthening the overall strength of the graduate supervisor team,actively promoting the adjustment and upgrading of the disciplinary and professional structure,strengthening the construction of resource platforms and deepening the implementation of collaborative education mechanisms,and continuously expanding and deepening the new pattern of international exchange and cooperation.Through the comprehensive promotion of the above paths,the aim is to fully build a model for the improvement and governance of graduate education quality.

Coupling Aquaculture—Crop Productions and Using of Water Drained from Ponds Rearing Clarias gariepinus as Fertilizer for Okra Production (Abelmoschus esculentus var. Clemson spineless, L. Moench)

The present study concerns the revalorization of drained water from aquaculture ponds rearing Clarias gariepinus on okra crops. The rearing was carried out at the farm of Gaston Berger University in 100 m2 ponds. In each pond, the individuals of C. garipinus with an average weight of 6 ± 0.3 g were stocked at a density of 11 per m2. The water temperature and pH were measured during the experiment. The control fishing is carried out every month to monitor variations in the weight and size of reared individuals. The plant production is carried out in elementary plots measuring 3 m × 1.5 m. Each plot was fertilized with either: drained water from C. gariepinus rearing (DWC), poultry droppings (PD), cow dung (CD) and mineral fertilizer (NPK). Treatments are carried out in tripliqua with either river water (RW), RW + the recommended dose of NPK (RD-NPK), RW + RD-PD, RW + RD-CD, DWC, DWC + 25% RD-NPK, DWC + 50% RD-NPK, DWC + 75% RD-NPK, DWC + 25% RD-PD, DWC + 50% RD-PD, DWC + 75% RD-PD, DWC + 25% RD-CD, DWC + 50% RD-CD, DWC + 75% RD-CD. Growth parameters and yield of okra were determined. The average temperature in the rearing environment was 27.6 ± 1.5˚C and pH 7.9 ± 1.1. After six (06) months of rearing, C. gariepinus individuals reached an average weight of 850.12 ± 1.3 g and an average height of 52.44 ± 1.1 cm. The daily weight gain and specific growth rates over this period were 3.9 g per day and 2.8% per day, respectively. The treatment T1 (RW + DR-NPK) gave the highest mean collar diameter and mean plant height with 2.3 ± 0.9 cm and 61.6 ± 32 cm, respectively. In T4 (DWC), the mean height of plants was 38.8 ± 23.5 cm and mean collar diameter 1.4 ± 0.8 cm. The growth performance in T4 was comparable to that of RD-CD (T3), but different from RD-NPK (T1) and RD-PD (T2). The highest average number, average weight, average length and average diameter of fruits were noted in treatments T13 (RW + RD-75%CD) and T7 (DWC + 75% RD-NPK). The best yields were noted in T1 (RW + RD-NPK) = 10.8 ± 5.4 t·ha−1, T5 (DWC + 25% RD-NPK) = 9.2 ± 4.6 t·ha−1 and T4 (DWC) = 8.6 ± 4.3 t·ha−1 which are comparable and higher than those obtained in T2 = 5.7 ± 2.8 t·ha−1 and T3 = 7.5 ± 3.8 t·ha−1.

Modeling impact of culture facilities on hydrodynamics and solute transport in marine aquaculture waters of North Yellow Sea

An increasing number of marine aquaculture facilities have been placed in shallow bays and open sea,which might significantly affect hydrodynamic and solute transport processes in marine aquaculture waters.In this study,a coupled hydrodynamic and solute transport model was developed with high-resolution schemes in marine aquaculture waters based on depth-averaged shallow water equations.A new expression of drag force was incorporated into the momentum equations to express the resistance of suspended culture cages.The coupled model was used to simulate the effect of suspended structures on tidal currents and the movement of a contaminant cloud in the marine aquaculture of the North Yellow Sea,China.The simulation results showed a low-velocity area appearing inside the aquaculture cage area,with a maximum reduction rate of velocity close to 45%under high-density culture.The results also showed that tidal currents were sensitive to the density of suspended cages,the length of cages,and the drag coefficients of cages.The transport processes of pollutants inside aquaculture facilities were inhibited away from the vicinity of the culture cage area because of the diminished tidal currents.Therefore,the suspended cages significantly affected the transport processes of pollutants in the coastal aquaculture waters.Furthermore,the reduced horizontal velocity significantly decreased the food supply for the aquaculture areas from the surrounding sea.

An IoT-Based Aquaculture Monitoring System Using Firebase

Indonesia is a producer in the fisheries sector,with production reaching 14.8 million tons in 2022.The production potential of the fisheries sector can be optimally optimized through aquaculture management.One of the most important issues in aquaculture management is how to efficiently control the fish pond water conditions.IoT technology can be applied to support a fish pond aquaculture monitoring system,especially for catfish species(Siluriformes),in real-time and remotely.One of the technologies that can provide this convenience is the IoT.The problem of this study is how to integrate IoT devices with Firebase’s cloud data system to provide reliable and precise data,which makes it easy for fish cultivators to monitor fishpond conditions in real time and remotely.The IoT aquaculture fishpond monitoring use 3 parameters:(1)water temperature;(2)pHwater level;and(3)turbidity level of pond water.IoT devices use temperature sensors,pH sensors,and turbidity sensors,which are integrated with a microcontroller and Wi-Fi module.Data from sensor readings are sent to the Firebase cloud via theWi-Fi module so that it can be accessed in real time by end users with an Androidbased mobile app.The findings are(1)the IoT-based aquaculture monitoring system device has a low error rate in measuring temprature,pH,and turbidity with a percentage of 1.75%,1.94% and 9.78%,respectively.Overall,the total average error of the three components is 4.49%;(2)in cost analysis,IoT-based has a cost-effectiveness of 94.21% compared to labor costs.An IoT-based aquaculture monitoring system using Firebase can be effectively used as a technology for monitoring fish pond conditions in real-time and remotely for fish cultivators that contribute to providing an IoT-based aquaculture monitoring system that produces valid data,is precise,is easy to implement,and is a low-cost system.

Phosphorus speciation,transformation and benthic processes with implications for environmental impacts in the aquaculture area of Rushan Bay

Phosphorus(P)is an essential nutrient for many organisms in the ocean,which plays a central role in the stability of ecosystems and the evolution of the environment.The distribution,occurrence and source-sink process of P in offshore waters are highly influenced by mariculture activities.P transformation in water-sediment system is the key process in P cycling,however,the mechanism is poorly documented in the coastal sea which is influenced by human activities.Based on the comprehensive surveys in the adjacent waters outside Rushan Bay in May,July and August 2014 and February 2015,the form and transformation of P in the suspended particulate matter(SPM)and surface sediment were analyzed.The results showed that contents of total P,authigenic P and organic P of SPM increased with the increase in distance from the shoreline off Rushan Bay,and the detrital-P decreased.The partition coefficient of P between water and SPM was related to the chemical activity of different forms of P,and a higher reactivity of inorganic P associated with SPM was observed.Hypoxia induced by mariculture changes the distribution and morphological composition of P in SPM and sediment in this typical aquaculture area,which can result in a conversion of sink to source of P in the sediment,thereby having a significant impact on the regional nutrient budget and associated with eutrophication.

Chicken Eggshell as an Innovative Bioflocculant in Harvesting Biofloc for Aquaculture Wastewater Treatment

Implementation of biofloc technology(BFT)system in aquaculture industry shows high productivity,low feed conversion ratio,and an optimum culture environment.This study was divided into two phases.The first phase involved maintaining the water quality using the optimum carbon-to-nitrogen ratio by manipulating pH in culture water.The second phase examined the performance of harvesting biofloc(remaining phytoplankton and suspended solids in the system)using chicken eggshell powder(CESP).This study showed that pH 7 to 8 were the best biofloc performance with high removal percentage of ammonia(>99%)with a remaining ammonia concentration of 0.016 mg L^(−1)and 0.018 mg L^(−1),respectively.The second phase of this study was performed to determine the optimal formulation and conditions of using CESP as a bio-flocculant in harvesting excess biofloc.The use of eggshell showed a higher harvesting efficiency of more than 80%under the following treatment conditions:0.25 g L^(−1)of eggshell dosage;with rapid and slow mixing rates of 150 and 30 rpm,respectively;30 min of settling time;settling velocity of 0.39 mm s^(−1)and pH of 6 to 7.Therefore,the results indicated that biofloc would be the best green technology approach for sustainable aquaculture wastewater and the CESP is an organic matrix that environmental-friendly bio-coagulant for biofloc harvesting.

Pollution characteristics and risk assessment of organophosphate esters in aquaculture farms and natural water bodies adjacent to the Huanghe River delta

To date,little attention has been paid to the effects of organophosphate esters(OPEs)pollution on aquacultural environment and aquatic product safety.Huanghe(Yellow)River delta area is one of the largest aquaculture centers in China,where ecological security protection is crucial in the national strategy of China.To explore the pollution characteristics,bioaccumulation,and health risks of OPEs in aquaculture farms in the Huanghe River delta and natural water bodies in the adjacent seas,five species of organisms from different farm types nearby the Huanghe River delta,and the corresponding culture water and sediments were sampled in this study.The total concentrations of Σ_(13)OPEs in water,sediments,and organisms were 51.53-272.18 ng/L,52.63-63.17 ng/g dry weight(dw),and 46.82-108.90 ng/g dw,respectively.Among the five types of culture ponds,the water samples from the swimming crab and hairy crab culture ponds exhibited higher OPEs,the concentration of OPEs in the sediments from the few ponds was relatively balanced,and the OPEs in the organism from the holothurian ponds was higher.Tris(1,3-dichloro-2-isopropyl pho sphate)(TDCP)was the main contaminant in water samples and tripropyl phosphate(TPrP)in sediments and organisms.However,trisphenyl phosphate(TPhP)showed the strongest bioaccumulation ability,followed by 2-ethylhexyl diphenyl phosphate(EHDPP)and TPrP.The bioaccumulation capacities of the five species were as follows:prawn>holothurian>hairy crab>swimming crab>carp.These five types of organisms,as main seafood in human consumption,were at low risk of negative impacts of pollution.However,the risk from the mixture of organophosphate flame retardants(OPFRs)still requires more attention due to the increasing consumption and production in the world.

The dissolution of total suspended solids and treatment strategy of tailwater in a Litopenaeus vannamei recirculating aquaculture system

In recirculating aquaculture systems(RASs),the effective treatment of aquaculture tailwater is essential to maintain the health of the RAS.This study investigated the optimal time and method for tailwater treatment during three periods of the aquaculture of the Litopenaeus vannamei:nursery(0–26 d),middle(27–57 d),and later(57–104 d).The variation of several water parameters during the dissolution of total suspended solid(TSS)in tailwater,applied with the effects of ozone on the microorganism and water quality parameters were investigated.Results showed that the TSS concentrations in tailwater decreased with time,although not significantly(P>0.05),whereas total ammonia nitrogen(TAN),nitrite(NO-2-N),and nitrate(NO_(3)^(-)-N)increased significantly(P<0.05).Therefore,TSS should be removed from the tailwater as early as possible,being most optimal within 4 h.Ozone removed 38.24%–48.95%of TSS,17.78%–90.14%of TAN,and 87.50%–98.90%of NO-2-N after 4 h of treatment.However,it resulted in the significant accumulation of NO_(3)^(-)-N.Moreover,the total number of Vibrio and bacterial counts in aquaculture tailwater was reduced completely by ozone within 4 h.Thus,these results provided technical details and data support for the effective treatment of tailwater from shrimp RAS.

Evaluating the Effects of Aquaculture Wastewater Irrigation with Fertilizer Reduction on Greenhouse Tomato Production,Economic Benefits and Soil Nitrogen Characteristics

The utilization of aquaculture wastewater as irrigation is an effective way to recycle and reuse water and nitrogen fertilizer resources because it contains numerous nutrients.However,it is still unclear that the pattern of substituting aquaculture wastewater irrigation for fertilizer supplementing is conducive to improving the soil nitrogen status,fruit yield and water-fertilizer use efficiency for tomato production.In this context,the experiment was intended to establish the appropriate irrigation regime of aquaculture wastewater in tomato production for freshwater replacement and fertilizer reduction to ensure good yields.Pot experiments were conducted with treatments as farmers accustomed to irrigation and fertilization used as control(CK),1.75 L aquaculture wastewater with base fertilizer(W1),2 L aquaculture wastewater with base fertilizer;and 2.25 L aquaculture wastewater with base fertilizer(W3).We examined the effects of aquaculture wastewater irrigation on soil nitrogen distribution,Nrelated hydrolases,tomato yield,and economic benefits.The results showed that the control treatment had the highest N input,about 24.68%higher than the W3 treatment,while the yield was only about 7.81%higher than W3.This indicated that the overuse of chemical fertilizer was present in the current tomato production.Although the reduction of fertilizer in aquaculture wastewater irrigation caused a decrease in tomato production,this economic loss can be compensated by cost savings in the wastewater disposal.Among aquaculture wastewater treatments,the W3 treatment had the highest overall benefit,achieving 62.63%freshwater savings,37.50%fertilizer input reduction,and an economic return of approximately 19,466 Yuan per hectare higher than the control.Additionally,increasing the irrigation volume of aquaculture wastewater could provide more available nutrients to the soil,which were more prevalent in the form of organic nitrogen.The lower soil nitrate reductase activities(NR)under aquaculture wastewater treatments after harvesting also proved that this pattern was beneficial to reduce soil nitrate nitrogen residues.Overall,the results demonstrate that aquaculture wastewater irrigation alleviates the soil nitrate residues,improves nutrient availability,and results in more economic returns with water and fertilizer conservation for the greenhouse production of tomatoes.

水产养殖中传统增氧设备增氧能力差异分析

为了解水产养殖中应用广泛的叶轮式增氧机、水车式增氧机、涌浪式增氧机和曝气式增氧机4种型式的增氧机的增氧性能水平,统计和分析了国内主要增氧设备生产企业2020年以来生产的145台不同型式增氧机的增氧能力试验数据。结果显示:1)部分企业生产的叶轮增氧机的增氧性能有所下降;2)水车式增氧机增氧性能有大幅提高,部分产品超过了SC/T 6010—2018《叶轮式增氧机通用技术条件》中规定同规格叶轮式增氧机的要求;3)涌浪式增氧机增氧性能总体呈上升趋势;4)曝气式增氧机具有较强的增氧性能,但配套风机形式不同、相同配套功率但曝气管不同的配置,其增氧性能存在较大差异。本研究为养殖用户在水产养殖系统增氧设备的配置时提供技术参考。

中国淡水池塘养殖发展的时空格局与前景展望

淡水池塘养殖是我国重要的渔业生产方式,解析其时空发展格局对于研判和把握未来的发展趋势十分必要。本研究以历年来中国渔业统计年鉴数据为基础,对近40年以来(1980-2020年,以5年为间隔;另有2021、2022年)全国31个省级行政单元淡水池塘养殖产量、面积、单产、占渔业总产量的比例进行了统计分析。结果表明:(1)养殖产量总体呈持续增加趋势,但增长率波动式放缓,1980-2020年增长率从181.9%下降至12.0%,2020-2022年均值为2348.3万吨,平均增长率为2.9%;(2)养殖面积亦呈持续增加趋势,但增长率波动式放缓,从53.1%下降至4.8%,2020-2022年均值261.8万hm^(2),平均增长率为0%;(3)单产总体呈波动式增长,但增长率从82.8%逐步下降至13.7%,2020-2022年均值604.7 kg/667 m^(2),平均增长率为2.4%;(4)各省淡水池塘养殖产量占渔业总产量比重的均值呈先上升后逐渐持平的趋势,1995-2022年波动持平变幅在44.6%~49.0%。受水土资源和环境保护刚性约束,当前淡水池塘养殖发展亟需从数量规模型向质量效益型转变,生态-经济合作型渔业综合体将是未来高质量发展的重要途径。

循环水养殖池塘中浮游动植物功能群特征及水质评价

为研究循环水养殖模式对水生态环境的中长期影响和浮游动、植物群落的演替规律及相互作用,2018和2019年3月下旬,在湖南长沙新建的12.7 hm^(2)池塘中修建24条长22 m、宽5 m、深2.7 m的两端有推水、底部有集污设施的养殖水槽中,放养2、3龄的鲢(Hypophthalmichthys molitrix)、鳙(Aristichthys nobilis)、草鱼(Ctenopharyngodon idella)、鲤(Cyprinus carpio),密度分别为1 200 kg·hm^(-2)、600 kg·hm^(-2)、120 kg·hm^(-2)和480 kg·hm^(-2)。在水槽中设9个采样点:推水设施区、养殖水槽中和水槽下游区各3个,调查分析循环水养殖模式刚投入使用和养殖一年后水质理化因子变动规律及浮游动植物群落结构变化。结果显示:浮游动植物种类与功能群数量变化较小,各功能群的相对重要性指数(IRI)变化剧烈;浮游植物优势功能群由功能群E(锥囊藻)、D(针杆藻)变化为功能群TD(丝状绿藻)、J(盘星藻、栅藻),演替原因为水流频繁紊动引起水层混合的空间差异;浮游动物优势功能群由功能群PSF(浮游小型滤食者)、PMF(浮游微型滤食者)变化为功能群PMF、PLF(浮游大型滤食者)及PSP(浮游小型捕食者),表现出更具生态稳定性的浮游动物大型化趋势,滤食性鱼类放养密度低是其重要原因;小体型滤食类浮游动物主要受耐富营养、带鞭毛、较小体型浮游植物的促进作用,在此基础上,大体型滤食类浮游动物还受到附着绿藻及适应中营养生境的硅藻等促进作用;浮游植物功能群G(空球藻)、W_(1)(尖尾、梭形裸藻)和X(球粒藻、衣藻、小球藻)对捕食类浮游动物的促进作用既包括上行效应直接传导,也包括以小型滤食类浮游动物为食物链环节的间接传导;循环水养殖一年后,各点位水质的空间差异进一步加大,但该池塘仍处于轻-中污染状态,符合养殖水质标准且整体较稳定。

益生菌在水产养殖可持续发展中的应用现状及展望

水产养殖在全球粮食安全中发挥着至关重要的作用,为人类提供优质蛋白源持续稳定供应提供了重要保障。益生菌是一类可用于水产养殖的有益微生物,不仅能够提高水产动物的生长性能、免疫能力,而且具有抑制致病菌、改善养殖水质等功效。益生菌在水产养殖中的推广应用可促进水产养殖业的健康可持续发展。因此,本文首先介绍了水产养殖中益生菌的定义与来源,详细阐述了益生菌对水产可持续养殖的意义以及益生菌在水产养殖中的实际应用,并对其未来研究方向进行了展望,以期为益生菌在水产养殖可持续发展中的推广和应用提供可靠的理论依据。

益生菌对幼鱼生长发育的影响及调控机制

近年来,高密度、集约化的水产养殖模式导致养殖鱼类疾病频发,其中幼鱼发病率和死亡率的上升严重影响水产养殖业的健康快速发展。如何保障幼鱼的健康是当前水产养殖业亟需解决的问题。益生菌能够通过多种方式提高幼鱼的抗病力、增强幼鱼对营养素的摄取、促进幼鱼的生长发育。已有大量的研究阐述了益生菌在幼鱼生长发育及免疫调节中的作用,但相关机制还需深入探究。本文综述了近年来益生菌在幼鱼生长发育及抗病方面发挥的有益作用及其可能的机制,讨论了益生菌在幼鱼养殖应用时可能存在的问题以及发展方向,为益生菌在水产动物幼体养殖中的应用提供了理论参考。