Coastal Aquaculture Areas Research Articles

Autonomous Extraction Technology for Aquaculture Ponds in Complex Geological Environments Based on Multispectral Feature Fusion of Medium-Resolution Remote Sensing Imagery

Coastal aquaculture plays a crucial role in global food security and the economic development of coastal regions, but it also causes environmental degradation in coastal ecosystems. Therefore, the automation, accurate extraction, and monitoring of coastal aquaculture areas are crucial for the scientific management of coastal ecological zones. This study proposes a novel deep learning- and attention-based median adaptive fusion U-Net (MAFU-Net) procedure aimed at precisely extracting individually separable aquaculture ponds (ISAPs) from medium-resolution remote sensing imagery. Initially, this study analyzes the spectral differences between aquaculture ponds and interfering objects such as saltwater fields in four typical aquaculture areas along the coast of Liaoning Province, China. It innovatively introduces a difference index for saltwater field aquaculture zones (DIAS) and integrates this index as a new band into remote sensing imagery to increase the expressiveness of features. A median augmented adaptive fusion module (MEA-FM), which adaptively selects channel receptive fields at various scales, integrates the information between channels, and captures multiscale spatial information to achieve improved extraction accuracy, is subsequently designed. Experimental and comparative results reveal that the proposed MAFU-Net method achieves an F1 score of 90.67% and an intersection over union (IoU) of 83.93% on the CHN-LN4-ISAPS-9 dataset, outperforming advanced methods such as U-Net, DeepLabV3+, SegNet, PSPNet, SKNet, UPS-Net, and SegFormer. This study’s results provide accurate data support for the scientific management of aquaculture areas, and the proposed MAFU-Net method provides an effective method for semantic segmentation tasks based on medium-resolution remote sensing images.

Deciphering the natural and anthropogenic drivers on the fate and risk of antibiotics and antibiotic resistance genes (ARGs) in a typical river-estuary system, China

This study conducts an in-depth assessment of the spatial distribution, ecological risks, and correlations among 12 antibiotics, antibiotic resistance genes (ARGs), and dominant microorganisms in a representative river-estuary system, classified by land use and hydrodynamic conditions. Sulfonamides and quinolones were identified as the major contaminants in surface waters, with aquaculture and healthcare wastewater responsible for over 80 % of the antibiotic load. Contrasting seasonal patterns were observed between freshwater (wet season: 215 ng/L, dry season: 99.9 ng/L) and tidal estuaries (wet season: 45.9 ng/L, dry season: 121 ng/L), attributed to antibiotic transport from terrestrial sources or coastal aquaculture areas. The estimated annual antibiotic influx into Jiaozhou Bay was 70.4 kg/year, posing a considerable threat to aquatic algae and disrupting the stability of aquatic food chain. BugBase predictions suggested that antibiotics in the environment suppressed bacteria characterized by biofilm formation (FB) and the presence of mobile elements (CME). However, ARG transmission was likely to drive the spread of CME, FB, and stress-tolerant (OST) bacteria within microbial communities. The significant positive correlations observed between sulfamethoxazole and 63 microbial genera indicate a broad distribution of microbial resistance, which exacerbates the potential for ARG accumulation and dissemination across both the bay and the Yellow Sea.

Regional distribution differences of antibiotics in tropical marine aquaculture area: Insights into antibiotic management and risk assessment

In recent years, global demand for marine aquaculture products has led to a significant rise in antibiotic use, particularly in tropical coastal aquaculture areas However, research on antibiotic residues in these environments remains limited, hindering a comprehensive understanding of their environmental presence and associated risks. This study investigates the regional distribution, ecological risks, and sources of 44 antibiotics in seawater across four coastal aquaculture areas in Hainan island (Wenchang, Sanya, Danzhou, and Wanning). Among the 44 antibiotics tested across 42 sampling sites, all were detected with a 100 % detection rate. Antibiotics such as Trimethoprim (TMP), Sulfanitran (APNPS), Sulfaquinoxaline (SQ), Sulfadimethoxine (SDT), Chloramphenicol (CHP), and Florfenicol (FLO) were consistently detected across all sampling sites. Total concentrations of detected antibiotics ranged from 0 to 818.79 ng.L−1, with sulfonamide antibiotics ranging from 0 to 629.49 ng.L−1, chloramphenicol antibiotics from 0 to 87.39 ng.L−1, tetracyclines from 0 to 221.39 ng.L−1, and fluoquinolones from 0 to 272.08 ng.L−1. The highest levels of antibiotic pollution were observed at the W5 sampling site in Wenchang, attributed to aquaculture wastewater discharge, while no antibiotics were found at D12 in Danzhou. In these regions, source analysis identified aquaculture and domestic sewage as the primary contributors to antibiotic pollution in these regions. Correlation analysis with environmental factors revealed significant influences of factors such as SAL, kPa, TN, SPC, and pH on sulfonamide and chloramphenicol antibiotics. Health risk assessment indicated moderate to high risks to aquatic organisms from antibiotics like NOR, CIP, ENR, OFL, TMP, and SMX in the study areas, underscoring the need for preventive measures, stricter regulation of antibiotic use, and enhanced ecological risk monitoring in aquaculture regions. This study provides critical insights into antibiotic contamination in Hainan's coastal aquaculture areas, highlighting the urgent need for further research into the occurrence and ecological impacts of these emerging pollutants in marine environments.

Detection and mitigation of soil salinization risk from saline/brackish water aquaculture in coastal areas: an application of remote sensing and managed aquifer recharge

This study focuses on detecting and mitigating soil salinization in four coastal areas of the Mekong Delta (Vietnam). Salinity patterns in the soils of the Mekong River Delta are not random but linked to land use practices and distance to the sea. We examine two quick yet reliable remote sensing-based techniques to detect the coastal aquaculture area and separate it from the inland freshwater farmland. These techniques can eventually be used to identify locations with an elevated risk of salinization in other coastal regions. Finally, we investigate a salinization mitigation solution based on creating a managed aquifer recharge system along the buffer zone that separates the coastal aquaculture area from the inland freshwater agriculture area. The implementation of an infiltration pond system is technically feasible in the Mekong Delta provided that hydrogeological characteristics, the fresh-saline interface position, and freshwater demands are considered. The transitional zone between freshwater agriculture and brackish water aquaculture in Bac Lieu, Soc Trang, Tra Vinh and Ben Tre provinces is optimal for implementing an aquifer recharge/freshwater barrier scheme.

Water pollution influencing contamination of Vibrio bacteria in the coastal aquaculture area of Chanthaburi and Trat Provinces

Water pollution influencing contamination of Vibrio bacteria in the coastal aquaculture area of Chanthaburi and Trat Provinces

Testing the applicability of the Modelling-Ongrowing Fish farms-Monitoring B (MOM-B) investigation system for assessing benthic habitat quality in the manila clam Ruditapes philippinarum aquaculture areas

The coastal aquaculture areas have been subject to a variety of anthropogenic pressures in recent studies, and reasonable environmental quality assessment is essential for both ecological conservation and production practices. However, there are significant differences between the results produced from various environmental quality assessment regarding the focus of the evaluation and the fundamental methodology. Furthermore, many of these methods are very specific and difficult to adapt to general applications. Here, we utilized the Modelling-Ongrowing fish farms-Monitoring B investigation system (MOM-B), we assessed the benthic habitat quality of benthic bivalve aquaculture areas in the Xiaoqing River estuary located in Laizhou Bay, China. The aim was to validate the accuracy and practicality of this system. The biological, chemical, and sensory parameters of the MOM-B system, temperature, chlorophyll a (Chl-a), food availability, and planktonic larvae were evaluated throughout the investigation area during the summer of 2021. The MOM-B results indicated that the benthic habitat quality in the survey area was good and lightly disturbed, but the quality in the middle tide area began to deteriorate in August, the hottest month of the summer. Environmental factors indicated that the combined effects of high temperatures and fine sedimentation had led to increased environmental stress in the middle tide area. Food availability and population recruitment also suggested that the benthic habitat quality was better in the high tide and low tide areas than in the middle tide area, and more favorable for the survival of Manila clams. The accuracy, sensitivity, and discriminatory ability of the MOM-B system were demonstrated by environmental and biological indicators. This work showed that the MOM-B system is a practical, simple, and sensitive environmental assessment tool that is easy to implement in estuarine and benthic bivalve aquaculture areas. It can be used for long-term continuous monitoring and as an early warning tool for benthic habitat quality.

Coastal ecological disasters triggered by an extreme rainfall event thousands of kilometers inland

The world is experiencing an increase in the frequency and intensity of extreme weather events, yet the influences of remote inland extreme weather events on the coastal ecosystem thousands of kilometers away remain poorly understood. Here we tracked the chain ecological effects of an extreme rainfall event in North China from terrestrial rivers to coastal aquaculture area of the eastern Shandong Peninsula. Our data suggest the autumn flood resulted from extreme rainfall event leads to abnormally low turbidity in the North Shandong Coastal Currents and coastal red tide blooms by introducing anomalous freshwater with an exceptionally high nitrogen-to-phosphorus ratio into the Bohai Sea. Lower salinity, stronger light conditions caused by limpid coastal currents, and phosphorus limitation resulting from red tide blooms account for huge kelp loss offshore of the eastern Shandong Peninsula. This study underscores the importance of considering multidisciplinary observation for risk management of unexpected extreme weather events.

Organic nutrient availability and extracellular enzyme activities influence harmful algal bloom proliferation in a coastal aquaculture area

Small-scale but highly destructive harmful algal blooms (HABs) are increasingly observed in coastal aquaculture areas. However, the impact of elevated organic nutrients generated during mariculture production and their bioavailability for HABs are not yet fully understood. This study investigated the population dynamics of HAB-causing species and the hydrolytic dynamics of different extracellular enzyme activities (EEAs) along with variations in environmental inorganic and organic nutrients during a dinoflagellate bloom of Prorocentrum shikokuense adjacent to the coastal aquaculture area in Sansha Town, located in the East China Sea. The results indicated that both inorganic and organic nutrients were enriched in the study area, with organic nutrients comprising more than half of the total nutrient content. The presence of enriched organic nutrients and a high N:P ratio significantly contributed to bloom occurrence. Organic nutrient concentrations played a predominant role in controlling both the density and duration of the P. shikokuense bloom. The significant increase in EEAs during the bloom stages, primarily contributed by P. shikokuense, emphasized the crucial hydrolytic role of extracellular enzymes in nutrient recycling and supply for the bloom. The enzymatic kinetic parameters indicated enhanced efficiency in the recycling of organic nutrients as the bloom progressed. This study highlights the significant role of organic nutrients facilitated by EEAs in determining the occurrence, duration, and magnitude of HABs in coastal aquaculture areas.

Vertical distribution of Fe, P and correlation with organic carbon in coastal sediments of Yellow Sea, Eastern China

The coastal zone is considered as a major carbon pool. Iron minerals and phosphates are vital factors affecting the amounts and occurrence of total organic carbon (TOC) in sediments. However, coupling mechanisms of iron (Fe) and phosphorous (P) in the source-sink transition of TOC in coastal sediments is poorly understood. This study characterized the distribution of Fe, P and TOC contents of three independent 170 cm sediment cores sampled from a coastal aquaculture area in the eastern Jiangsu Province, and quantified the correlations among Fe, P, median grain diameter (Dx(50)), and TOC. The results showed total phosphorus (TP) content ranges in a scope of 337.4-578.0 mg/kg, and many depths recorded moderate P eutrophication. Inorganic phosphorus (DA + IP) and biogenic apatite were the primary components of TP, accounting for 25.19–55.00 and 26.71–49.62%, respectively. The Fe contents varied from 987.9 mg/kg to 2900.7 mg/kg, in which oxidized iron (Fe ox ) accounted for about 62.2–79.4%. In the vertical profile, the TOC was positively correlated with the contents of low-crystallinity Fe-bearing carbonates (Fe carb ), high crystallinity pyrite (Fe Py ), iron-bound phosphorus (P CDB ), manganeses (Mn), and nitrogen (N), while it was negatively correlated with DA + IP, organic phosphorus (OP), and Dx(50). Based on the the partial least squares (PLS) model, we proposed that the higher Fe Py , Mn, magnetite (Fe Mag ), Fe carb , P CDB , amorphous exchangeable Fe (Ex-Fe), and authigenic apatite phosphorus (Bio-P) in sediments represent the high capacity for TOC sink, whereas, higher DA + IP, and OP indicate a TOC conversion to the source. The non-siginificat indication of Fe ox on TOC source-sink is due to its surplus and strong reactivity relative to TOC content. These revealed correlations provide a theoretical reference for understanding and regulating the burial rate and storage of TOC by changing the input of Fe minerals and P components into coastal sediments.

The dynamics of red Noctiluca scintillans in the coastal aquaculture areas of Southeast China.

Noctiluca scintillans (NS) adds an aesthetic appeal to many coastal areas because of their bioluminescence. An intense bloom of the red NS frequently occurs in the coastal aquaculture region of Pingtan Island in Southeastern China. However, when NS exceeds in abundance, it causes hypoxia which has devastating impacts on the aquaculture. This study was conducted in the Southeastern part of China with an aim to examine the relationship between the profusion of NS and its impacts on marine environment. Samples from four stations on Pingtan Island were collected for 12months (January to December 2018) and were later analyzed in laboratory against five parameters, namely temperature, salinity, wind speed, dissolved oxygen, and chlorophyll a. Results showed that the NS blooms were particularly active during the months of May and June in the Pingtan Island area. The seawater temperatures during that time were recorded between 20 and 28.8°C indicating the optimum survival temperature for NS. The NS bloom activity ceased above 28.8°C. A principal component analysis (PCA) indicated that the richness of NS was positively associated with temperature and salinity, whereas there was a significant reverse correlation between NS accumulation and wind speed. NS is a heterotrophic dinoflagellate and relies on the predation of algae for reproduction; therefore, a significant correlation was observed between NS abundance and chlorophyll a concentration, and an inverse correlation was observed between NS and phytoplankton abundance. Additionally, red NS growth was observed immediately following the diatom bloom, suggesting that phytoplankton, temperature, and salinity are the essential factors in the evolution, progression, and termination of NS growth.

Coastal Aquaculture Area Extraction Based on Self-Attention Mechanism and Auxiliary Loss

With the development of deep learning in satellite remote sensing image segmentation, convolutional neural networks have achieved better results than traditional methods. In some full convolutional networks, the number of network layers usually increases to obtain deep features, but the gradient disappearance problem occurs when the number of network layers deepens. Many scholars have obtained multiscale features by using different convolutional calculations. We want to obtain multiscale features in the network structure while obtaining contextual information by other means. This article employs the self-attention mechanism and auxiliary loss network (SAMALNet) structure to solve the above problems. We adopt the self-attention strategy in the atrous spatial pyramid pooling module to extract multiscale features while considering the contextual information. We add auxiliary loss to overcome the gradient disappearance problem. The experimental results of extracting aquaculture areas in the Jiaozhou Bay area of Qingdao from high-resolution GF-2 satellite images show that, in general, SAMALNet achieves better experimental results compared with UPS-Net, SegNet, DeepLabv3, UNet, DeepLabv3+, and PSPNet network structures, including recall 96.34%, precision 95.91%, F1 score 96.12%, and MIoU 92.60%. SAMALNet achieved better results extracting aquaculture area boundaries than the other network structures listed above. The high accuracy of the aquaculture area can provide data support for the rational planning and environmental protection of the coastal aquaculture area and promote more rational usage of the coastal aquaculture area.

Numerical study of hydrodynamic effects on Manila clam population distribution and transport in the Southwest Laizhou Bay, China

Pelagic larvae of marine organisms are abundant on many continental shelves. Due to their importance as a biological resource and contribution to marine biodiversity, the dynamics of pelagic larvae have received wide attention. Numerical models are an efficient approach to assessing pelagic larval transport driven by various ocean dynamics. However, few studies have focused on the pelagic larval distribution of Manila clam populations and related dynamic factors in the southwestern Laizhou Bay (SLB) during late spring. A hydrodynamic model including realistic meteorologic and oceanic boundary conditions was coupled with a larval transport model to describe the pelagic larval distribution and transport processes. The hydrodynamic model was validated with observational and satellite-derived data. Effects of hydrodynamics and biological behavior on pelagic dynamics were further simulated with numerical experiments. During the early planktonic period, most clam larvae in the SLB were transported eastward or northeastward. Two potential larval settlement areas (LSAs) were recognized: the east side of the dike outside Guangli port and the Lao River estuary. The dominant controlling factor was southerly wind, and larvae's response to river plume or estuarine circulation played a secondary role. Larval transport depended on bottom subtidal currents when late-stage larvae settled near the bottom layer. The hydrodynamic and larval transport model established in this study can be applied to other bays and coastal waters. Understanding the clam larval distribution and transport dynamics in the SLB can provide a reference for predicting LSAs and biological resource management in coastal aquaculture areas.

Quantitative suitability evaluation and spatial zoning for seawater desalination water intake site selection

Seawater desalination water intake site selection has an important impact on the investment, water production cost, stable operation, and safety of seawater desalination plants. Site selection is affected by many factors, such as the natural geography, ecological environment, and social economy of coastal zones; some constraints can be directly identified as unsuitable areas for these construction projects. For the shallow water intake method of seawater desalination, this study selects suitability evaluation indicators for seawater desalination water intake site selection from the three influencing factors of basic geography, water environment, and industrial development and constructs a suitability evaluation model based on the multifactor spatial overlay analysis of the Geographic Information System platform. This model carries out a quantitative suitability evaluation of the seawater desalination water intake site selection and realizes the suitable spatial zoning for spatially selecting the water intake, thus forming a scientific, quantitative, and spatial suitability evaluation system for this process. The evaluation method was applied in the Rongcheng city offshore area of China and analyzed. The evaluation results showed that the suitable areas for seawater desalination water intake site selection comprised 304.8 square kilometers, which were mainly distributed in the offshore areas in northern Rongcheng city and near the coastline areas of its central and southern regions. The unsuitable areas covered 292.4 square kilometers, mainly distributed in the marine ecological red line areas and the coastal aquaculture areas of Rongcheng city. The evaluation results met the site selection needs of the seawater desalination water intake project in Rongcheng city. This study improves upon the existing method of seawater desalination intake site selection at the theoretical and technical levels and provides a scientific basis for the location selection and planning for water intake in large spatial ranges of coastal waters.

Classification of Aquaculture Waters through Remote Sensing on the Basis of a Time-Series Water Index

Zhang, C.; Gao, L.; Lu, Z.; Liu, H.; Zhu, H., and Tang, K., 2022. Classification of aquaculture waters through remote sensing on the basis of a time-series water index. Journal of Coastal Research, 38(6), 1148–1162. Coconut Creek (Florida), ISSN 0749-0208. Accurate spatial distribution information on aquaculture is crucial for scientific aquaculture management, postdisaster evaluation, and water environment protection. At present, large-scale aquaculture areas can be quickly and accurately monitored using remote-sensing technology. However, most previous studies gave importance only to extracting aquaculture areas and ignored the classification of aquiculture types. Although several researchers classified aquaculture modes, the waters in aquaculture areas were unclassified. Moreover, classification of the aquaculture target is usually performed on a single remote-sensing image, which lacks time-series information. To examine existing issues, the current study selected the coastal marine aquaculture areas in the southern Lvushunkou District of Dalian. First, a normalized difference aquaculture water index (NDAWI) was constructed on the basis of the measured data through a spectral feature analysis. Second, NDAWI was extracted from Sentinel-2 images to construct a time-series data set, and the random forest classification method was applied to classify kelp and wakame aquaculture waters. Last, the experimental outcomes of the NDAWI data set were compared with those of other time-series data sets. Results showed that the overall accuracy of the NDAWI time-series data set was 92.11%, which showed an improvement of 7.68%, 17.66%, 4.50%, and 11.50% compared with the values for normalized difference chlorophyll index, normalized difference vegetation index, and greenness component of tasseled cap transformation data sets and single-phase images, respectively. The NDAWI time-series data set constructed in this study exhibited a dramatically improved classification accuracy compared with other time-series data sets. It has a high application value for identifying relevant aquaculture areas.

Distribution of dinoflagellate cysts in the modern sediments from the coastal aquaculture area and its adjacent oceanic shelf in southeast China

Changes in nutrient loading due to coastal aquaculture and the targeted expansion of monitoring programs over the past few decades have amply demonstrated a marked increase in harmful algal blooms (HABs). In this study, viable dinoflagellate cyst composition and assemblages were investigated by evaluating and classifying their distribution patterns in surface sediments of the Fujian aquaculture coastal region of southeast China. The surface sediment at 5 stations during the spring and summer of 2019 to classify the dinoflagellate cysts present and identified 36 species representing six known and three uncertain taxa groups. The highest cyst was recorded at coastal station P11 in the spring (744.7 cysts g−1 DW), while the lowest cyst was observed at coastal station P5 in spring (50.9 cysts g−1 DW). The number and abundance of the heterotrophic species were greater than the autotrophic species, with the highest species volume belonging to the protoperidinioid group. We also detected potentially harmful algae bloom cysts that hold the potential to form their initial blooms in the sediments. It is important to note that six dinoflagellate cysts were found in the waters along the Fujian coast, as compared to historical data. Although the abundance of these cysts was not high, their presence indicates a potentially grave risk for toxic red tides. More alarmingly, these results suggest that seedbeds may trigger future blooms and outbreaks of toxic species in the present study area.

Macrobenthic community status at coastal cage aquaculture area in Xuan Dai bay, Phu Yen province, Vietnam

Lobster cage culture started around 1990 in Xuan Dai bay and grew fast in recent years, contributing significantly to the socio-economic development of the region. But the impact on the ecological environment of cage culture operation also needs to consider. This paper points out the status of the macrobenthic community, studied at two stations inside the cage culture area (X1, X2) and one reference station (Xr) in the non-cage culture area. A total of 90 samples with 5 replicate samples per station were collected in six surveys during the dry and rainy seasons from June 2019 to May 2020. These samples were classified and recorded into 80 taxa belonging to 49 families and 5 classes. The class Polychaetes had the most diverse species composition with 53 taxa (66% of the total number of taxa). The crustacean group had 14 taxa (18%) belonging to 13 families; Molluscs had 9 taxa (11%) belonging to 6 families of class Bivalvia. The echinoderms had 4 taxa (5%). Capitella capitata, a species known as an indicator of organic pollution, was recorded in both stations of the culture area but was not present at the reference station. Furthermore, some dominant species presented in the culture stations such as Cossura longocirrata (contributed 43.52% in station X1) and Ceratonereis sp. (contributed 27.57% in station X2). These species are considered opportunistic species that can adapt to disturbed environmental conditions. Significantly, the species of echinoderms group were only recorded in the reference station. The species composition was only about 24% similar to those at the cage culture stations. The species richness index (D) values ranged from 1.50 (X2.6) to 6.82 (Xr.3). The diversity index (H′) varied from 0.88 (X2.4) to 2.98 (Xr.3). The evenness index (J) had the lowest average value at station X2 (J = 0.59 ± 0.20) and the highest value at the reference station Xr (J = 0.78 ± 0.03). The indices D, H′ and J of the macrobenthic community at the reference stations have higher average values compared to those estimated at cage culture stations. These results proved cage culture activities have gradually impacted the benthic fauna, reduced biodiversity, and encouraged the appearance of opportunistic species. Thus, further studies on the macrobenthic community dynamic with ecological criteria are necessary to establish a set of biological indicators to monitor the environmental quality of the coastal aquaculture area.

Comprehensive evaluation of the impact of CuO nanoparticles on nitrogen transformation in the coastal aquaculture area

CuO nanoparticles (CuO NPs) are increasingly used in marine antifouling paints and as an antimicrobial antifouling agent in aquaculture industry, thus greatly increasing the probability of their release into the coastal aquaculture environments. With the wide application of CuO NPs, their potential environmental impact is currently highly topical focus of concern. In this study, the short term (7 days) and long term (35 days) effect of CuO NPs on the nitrogen transformation of sediment in the coastal aquaculture area were investigated. It was demonstrated that the addition of CuO NPs could lead to the increase in ammonium and decrease in nitrate concentration after a long-term exposure. Lactate dehydrogenase (LDA) release assays and NADH detection suggested that CuO NPs could significantly inhibit the viability of bacteria. Metagenomic results further indicated that CuO NPs could obviously impact the functional gene and metabolic enzymes related to nitrogen metabolic pathway and glycolysis pathway which confirmed the inhibitory impact of CuO NPs on nitrogen transformation. Overall, this study highlights the impact of CuO NPs on the nitrogen transformation in the sediment of coastal aquaculture area and reveals the release of CuO NPs should be controlled because of their potential for eutrophication.

Spatio-temporal patterns and sustainable development of coastal aquaculture in Hainan Island, China: 30 Years of evidence from remote sensing

The fast-growing coastal aquaculture industry provides nutritious seafood and huge wealth for society, but also affects the natural environment and coastal ecosystems. There is an urgent need to realize the sustainable development of coastal aquaculture with regard to the trade-off between economic development and ecological conservation. Satellite remote sensing provides long-term data on the distribution and dynamics of aquaculture, which is essential for the design of suitable policy interventions for sustainable development. In this study, Landsat time series were used to map the tendencies and dynamics of aquaculture ponds for 30 years (1987–2018) in the coastal area of Hainan Island, China. The results showed that (1) the coastal aquaculture area of Hainan Island first increased rapidly, then increased slowly, and then decreased slightly in the past 30 years, increasing by approximately 10 times. The largest annual change rate of aquaculture ponds was between 2000 and 2005 (1597 ha/year), followed by the period 1995–2000 (1414 ha/year). (2) The development of aquaculture was unbalanced in the space, and Wenchang City in the northeast of Hainan Island accounted for 47.87% of the total aquaculture area in 2018. The aquaculture centroids moved from the center of Hainan Island to the northeast with a total migration distance of 72.9 km from 1987 to 2018. (3) There were three different types of development tendencies in the coastal cities (counties) (aquaculture areas increased continually; aquaculture areas increased first and then decreased slightly; aquaculture areas increased first, and then decreased significantly), mainly related to the different regional characteristics and development orientations. The different evolution phases of coastal aquaculture in Hainan Island were driven by relevant national and local government policies. Formulating and implementing appropriate aquaculture policies according to local conditions, as well as promoting industrial upgrading of aquaculture with high-tech, are significant suggestions for sustainable aquaculture. This study provides baseline data for local managers to assess the development of coastal aquaculture and reference experiences of sustainable aquaculture for other tropical islands and countries.

Draft Genome Sequences of Putative Aerobic Anoxygenic Phototrophic Bacterial Strains Jannaschia sp. Strains AI_61 and AI_62, Isolated from Seawater around a Coastal Aquaculture Area.

ABSTRACTHere, we report the draft genome sequences of putative aerobic anoxygenic phototrophic bacterial strains Jannaschia sp. strains AI_61 and AI_62, isolated from seawater around a coastal aquaculture in Ainan, Ehime, Japan. These genome sequences could be useful for our understanding of the variation of aerobic anoxygenic phototrophs in the genus.

Probing the contamination characteristics, mobility, and risk assessments of typical plastic additive–phthalate esters from a typical coastal aquaculture area, China

Contamination characteristics, equilibrium partitioning and risk assessment of phthalate esters (PAEs) were investigated in seawater, sediment and biological samples collected from the Xiangshan Bay area during an annual investigation between January and November 2019. PAE concentrations detected in the mariculture environment in surface seawater, sediment, and biological samples were 172–3365 ng/L, 190–2430 μg/kg (dry weight [dw]), and 820–4926 μg/kg (dw), respectively. The dominant congeners in different media included di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), and di(2-ethylhexyl) phthalate (DEHP). The inner bay and the bay mouth were the gathering area of PAEs and heavily influenced by the mariculture activities, river inputs, and anthropogenic activities. The bioaccumulation of PAEs demonstrated benthic feeding fishes with relatively high trophic levels concentrated high levels of phthalates. The mobility of PAEs in sediment–seawater showed that the transfer tendency of low-molecular weight species was from the sediment to the water, which was in contrast with those of high-molecular weight PAEs. DEHP, DiBP and DnBP had various degrees of ecological risks in the aquatic environment, whereas only the DiBP posed potential risks in sediments. The current assessment of carcinogenic and noncarcinogenic risks posed by fish consumption were within acceptable limits for humans.