In present study, the morphology and species identification of the Neobenedenia parasites (Isolate Batam/IB) in the cage aquaculture were studied via morphological and molecular marker methods at Batam Island, Indonesia. The isolate Batam is morphological similar with Neobenedenia girellae, and it is considered to belong to the Neobenedenia genera. 394 bp of the 28S rRNA was amplified, and its similarity with other genera was between 85.86%−99.47%. The phylogenetic tree shows that IB, Neobenedenia melleni and Neobenedenia girellae are in a same cluster, and other Benedeniinae species form their own cluster. To sum up, IB is identified as the specie of Neobenedenia girellae and we support the theory that N. melleni and N. girellae are synonyms.

Dosidicus gigas is an important fishing target by Chinese squid-jigging fisheries, which is widely distributed in the Southeast Pacific Ocean. Its population is largely affected by climatic and environmental conditions on the fishing ground. In this study, we calculated the habitat suitability index (HSI) on the fishing ground of D. gigas in the Southeast Pacific Ocean off Peru from January to December during 1950 to 2015 based on sea surface temperature (SST) and the anomalies of sea surface height (SSHA), and variability in the environmental variables and habitat quality were further analyzed under the warm and cold phases of the Pacific Decadal Oscillation (PDO). The results suggested that PDO showed cold, warm and cold phases from 1950 to 2015. The anomalies of SST (SSTA) and SSHA during the cold PDO were significantly lower than those during the warm PDO. The cross correlation analysis suggested that both the SSTA and the SSHA were significantly positively correlated with the PDO index. However, and the HSI values on the fishing ground of D. gigas were significantly negatively correlated with the PDO index, SSTA and SSHA. During the cold PDO, the water temperature became cold, and the SSH decreased, these changes led to enlarged areas of suitable SST and SSHA for D. gigas, therefore, the favorable habitats largely increased. However, during the warm PDO, the water temperature became warm, the SSH elevated, whereas the ranges of suitable SST and SSHA contracted, all these changes resulted in the decrease of the suitable habitat of D. gigas. Our findings suggested that PDO regulated the environmental conditions on the fishing ground of D. gigas off Peru, and further significantly affected the habitat quality and suitable ranges of the habitat.

Illex argentinus was a short life cycle species. Its resource abundance is susceptible to changes in the marine environment, especially in its early life history stage. According to the production statistics of the Chinese squid jigging fleet during 2003−2016 in the Southwest Atlantic and the sea surface temperature (SST) of the spawning ground from satellite remote sensing, the correlation analysis method was used to select the featured area representing SST changes during the spawning season (June) of I. argentinus. Based on the assumption that the ratio of optimum SST range to the total area (Ps) of the spawning ground of I. argentinus is positively correlated with the abundance index (catch per fishing unit, CPUE, t/ship), the optimum spawning area and suitable sea water temperature range of I. argentinus were traced back, and a variety of multivariate linear prediction models of abundance index based on the environmental factors were established. The correlation analysis shows that there are significant correlations between SST and CPUE in two consecutive sea areas (Area 1, Area 2) in June. They are 42.5°−44°S, 57.5°−59°W (Area 1) and 39°−39.5°S, 45°−46°W (Area 2) respectively. The inferred spawning area of I. argentinus ranges from 37.5°S to 44°S and 41.5°W to 51.5°W, and the optimum SST in the spawning area is 16°C to 17.5°C. The SSTs of two featured areas (Area 1, Area 2) and Ps in the inferred spawning area are used to establish four types of multivariate linear prediction models of abundance index (ICPUE), the results show that the fourth model containing the featured areas and Ps in the inferred spawning area is superior to the other 3 models, and its prediction model of abundance index is ICPUE=1.390 4×Ps+0.261 9×SST_{Area 1}+0.096 2×SST_{Area 2}−3.248 0.

Based on the bottom trawl surveys in the Haizhou Bay and adjacent waters during spring and autumn of 2011 and 2013−2018, the performance of regular GAM and PCA-GAM was compared, and the distribution of Cynoglossus joyneri in this area was predicted. The predictive ability and fitting effect of the two GAMs were evaluated by cross-validation. The results showed that the goodness of fit and prediction effects of PCA-GAM were better than those of regular GAM. In spring and autumn, the abundance of C. joyneri in the southern waters was higher than that in the northern waters, and the abundance in the near-shore shallow waters was larger than that in the deep waters. The higher water temperature in the coastal waters of the southern Haizhou Bay was conducive to the development of gonads for the spawning groups during spring and autumn. The lower salinity was conducive to the growth and development of fish eggs and larvae. At the same time, the abundant prey resources in the coastal waters provides a large amount of food for it after spawning period. In this study, two GAMs were used to predict the resource distribution of C. joyneri in the Haizhou Bay in spring and autumn of 2018. The results showed that the predicted abundance by PCA-GAM were more consistent with the actual catches, and the performance of PCA-GAM was better than the regular GAM. This study provides a new method for studying the spatial distribution of marine organisms in the future.

Currently, the global nitrogen and phosphorus cycles are out of balance due to anthropogenic activities which produce a large amount of reactive nitrogen and phosphorus annually. The incremental N and P are mainly derived from production and application of synthetic N fertilizers, manure application, large areas of cultivated leguminous crops that could fix atmospheric N₂, and NO_x emitted from fossil fuel combustion. It should be noted that crop and livestock production systems are the major cause of human alteration of the global N and P cycles. Increased human sewage and fertilizer application in agricultural production have significantly raised the inputs of N and P nutrients to coastal ecosystems leading to a global spread of eutrophication. Most of these inputs are transported to the coastal ocean via river runoff and atmospheric deposition. More than half of the incremental N and P loads are related to anthropogenic sources. The Baltic Sea and East China Sea present typical eutrophication condition in developed country and developing country respectively. The mitigation strategies should focus on dual nutrient strategy for successful N and P reduction, including reduction of leaching and runoff from agricultural fields, growing perennial crops, effective application of fertilizers, and planting winter cover crops.

To better understand the ecological characteristics of the macro-fouling community in the northeastern waters of Pingtan Island, East China Sea, a study was conducted by test panels from June 2017 to May 2018. A total of 92 species of fouling organisms belonging to 13 phyla were recorded. The community composition was dominated by coastal warm-water species, and the main dominant species were sessile Amphibalanus reticulatus, Biflustra grandicella, Balanus trigonus, Ectopleura crocea, and motile Jassa falcata, and Maeropsis serratipalma. Bioattachment occurred throughout the year, the main period of settlement extended from June to August (the biomass ranged from 7 326.0 g/m² to 12 970.0 g/m²), and the off-seasons of settlement extended from December to February of next year (the biomass ranged from 39.5 g/m² to 1 580.5 g/m²). The main functional feeding group of macro-fouling organisms was suspension feeder. Temperature and salinity were the most important environmental factors affecting the geographical distribution of macro-fouling organisms. Water transparency, hydrodynamic conditions, surface runoff as well as human activity (such as aquaculture production) also had important impact on the settlement of macro-fouling organisms.

In this study, 40 groupers belonging to 10 genera of the subfamily Epinephelinae from Western Pacific were collected, and partial sequences of 16S rRNA gene and COI gene were amplified and determined. The molecular phylogenetic relationships were constructed and analyzed using maximum likelihood method. The results showed that the length of COI gene was 651 bp, encoding 227 amino acids. While the consensus sequences of 16S rRNA gene were 566 bp, with certain base insertion and deletion. The sequences of 16S rRNA gene were more conserved than those of COI gene. The phylogenetic tree of the 10 genera of the subfamily Epinephelinae was constructed and the results showed that Plectropomus was first separated and rooted at the base of the tree, indicating its evolutionary status was most primitive. 6 species from Plectropomus were clustered as a monophyletic group. Aethaloperca was close to Cephalopholis, which tightly clustered together. Variola was located between Plectropomus and Cephalopholis. Epinephelus was located at the top of the tree, indicating its advanced evolutionary status. The species from Epinephelus in the tree were clustered as two parallel branches, instead of a monophyletic group; Cromileptes, Triso, Hyporthodus, Anyperodon and Promicrops could not form an independent branch but cluster together with species from Epinephelus, indicating their close relationship within Epinephelus and some species might belong to Epinephelus.

This study investigated the oxidative stress and energy utilization responses of juvenile cobia (Rachycentron canadum) to environmental hypoxia stress, and provided reference for the healthy cultivation of cobia. Through the hypoxia stress-reoxygenation test, the oxidative stress and energy utilization indexes of liver and muscle tissues were measured after hypoxia ((2.64±0.25)mg/L) stress for 3 h and reoxygenation ((6.34±0.15)mg/L) stress for 8 h, 24 h and 48 h. The results showed that after hypoxia stress, the activity of malondialdehyde (MDA), catalase (CAT) and glutathione reductase (GR) in the liver were significantly lower than that in the control group (p<0.05), and the activity of lactate dehydrogenase (LDH) was significantly higher than that in the control group (p<0.05). MDA and lipid peroxidase (LPO) activities in muscle were significantly lower than those in control group (p<0.05), and superoxide dismutase (SOD) and LDH activities were significantly higher than those in control group (p<0.05). The contents of muscle glycogen and liver glycogen were significantly lower than those of control group (p<0.01). During reoxygenation, the contents of MDA, LPO, SOD, CAT, glutathione peroxidase (GPx) and GR in liver and muscle all increased differentially. Liver glycogen content was significantly higher than that of the control group 24 h after reoxygenation (p<0.05), and significantly lower than that of the control group 48 h after reoxygenation (p<0.05). Muscle glycogen content was significantly lower than that of control group after reoxygenation for 8 h, 24 h and 48 h (p<0.05). In conclusion, hypoxia stress can cause some oxidative damage to the body of cobia, and the enzyme activity and energy supply of liver and muscle tissues change. The reoxygenation environment after hypoxia stress causes more severe oxidative damage to the body, which can be gradually restored to the normal level through physiological regulation.

The full-length cDNA of glutathione S-transferase (Sc-GSTσ) and heat shock protein 90 (Sc-HSP90) genes were cloned from Sinonovacula constricta and their expression characteristics under ammonia nitrogen stress were analyzed. The results show that the full-length cDNA of Sc-GSTσ was 1 414 bp, and containing 639 bp open reading frame (ORF), encoding 212 amino acid polypeptides. The homology of amino acid sequence of Sc-GSTσ with other species’ GST amino acid sequence was 31.88%−43.40%. The full-length cDNA of Sc-HSP90 was 2 752 bp, ORF was 2 181 bp, encoding 726 amino acids. The amino acid sequence was 76.77%−87.05% homology with other species. Quantitative analysis showed that Sc-GSTσ and Sc-HSP90 genes were expressed in all tested tissues, the strongest expression being in the digestive gland. After exposure to ammonia, the mRNA expression of Sc-GSTσ and Sc-HSP90 were significantly up-regulated (p<0.05) in the digestive gland, indicating that ammonia stress induced stress response, both GST and HSP90 may be participate the process of detoxification or defense. However, the decrease of expression in the later period of stress is presumed to be due to the organism have limited ability to defense, which is not enough to protect the host from stress-induced cell damage.

Based on the data from the zooplankton survey in the waters around the Ningde nuclear power plant in January (winter), April (spring), July (summer) and November (autumn) 2018, the structure and seasonal changes of jellyfish communities in the area were analyzed. The potential risks of jellyfish to the safe production of nuclear power in Ningde were discussed. The results showed that there were seasonal changes in the species composition, abundance distribution and dominant species succession of jellyfish in the Ningde nuclear power plant area. The numbers of jellyfish species in the spring, summer, autumn and winter were 7, 16, 9 and 3, respectively. The mean abundances were (45.48±8.24) ind./m³, (50.26±12.13) ind./m³, (3.68±1.91) ind./m³, and (0.18±0.07) ind./m³, respectively. The main dominant species were Laodicea indica, Pleurobrachia globosa, Diphyes chamissonis and Euphysa aurata. The seasonal succession of dominant species was obvious. The correlation analysis between the change of jellyfish abundance and environmental factors showed that the abundance of jellyfish in spring and summer was significantly related to the total abundance of zooplankton, and its number was significantly related to the number of copepods in zooplankton in summer（p<0.05, R=0.363). The abundance of jellyfish communities in autumn and winter was mainly affected by salinity. The salinity of the sea area was relatively low in autumn and winter, and the temperature is also low, so the abundance of jellyfish was also low. According to the distribution characteristics of jellyfish in Ningde, the jellyfish abundance of 50 ind./m³ was considered as the risk threshold value, and summer was the potentially high-risk season for ecological disasters. It was necessary to focus on the 5−20 km away from the intake area in summer; followed by the spring, the focus was on the 2.5−5 km away from the intake area; in autumn and winter, the safety of nuclear power sources was basically not caused by jellyfish.