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.

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 macrobenthos materials samples collected in August 2009, October 2009, May 2010 and August 2010 in the Laizhou Bay, the present study analyzed species composition, abundance, biomass, community structure and compared with historical data of macrobenthos. The results suggested that 272 species of macrobenthos were identified in the research region, including 122 species of Polychaetea, 64 of Crustacea, 46 of Mullusca, 18 of Echinodermata, 9 of Pisces and 13 of other groups. The total average abundance was (1102.56±216.32) ind./m², average biomass was (28.16±8.45) g/m², Polychaetes were the most dominant groups in the abundance and Mollusks were dominant in the biomass. Regarding the spatial influence on macrobenthos, low values of abundance and biomass usually appeared in stations outside of the Huanghe River Estuary in the west of the bay, but high values occurred in the central of Bohai Sea. Regarding the temporal influence on macrobenthos, significant seasonal variations in the abundance and biomass were observed. The dominant species were distinct, the relative important species were Sternaspis sculata, Glycinde gurjanovae and Alvenius ojianus. Compared with the historical data, the species composition and dominant species had showed an obvious miniaturization trend.

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.

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.

As one of the most abundant species of family Notothenioidei, rock cod (Patagonotothen ramsayi) plays an important role in energy transfer in the food web in the Patagonian Shelf. Currently, the work on feeding ecology of this species mainly bases on the conventional stomach content analysis, which only reflects short-term variation in feeding. Therefore, this study analyzed the distribution of fatty acids in three tissues (muscle, liver and gonad) of rock cod, and analyzed whether fatty acids in these tissues can characterize their feeding habits and transfer of diet. The results indicate that 27 kinds of fatty acids were detected in the tissues of rock cod. The storage and use of fatty acids in liver and gonad tissues are not suitable for indicating the diet of rock cod because they are involved in growth and reproduction. Compared to liver and gonad tissues, the longer renewal cycle of muscle tissue may better reflect its absorption of fatty acids from food. For the analysis of fatty acids in the muscle tissue of the rock cod in different size groups, it is inferred that the small-size rock cod (immature individual, 100−240 mm) mainly fed on planktonic organisms. The benthic feeding characteristics of rock cod increase with the increasing of size, and the feeding pattern transfer from planktonic feeding to planktonic-benthic feeding. In addition, due to the consumption of a certain amount of fishery discards by rock cod, the contribution rate of saprophytic food chain to predatory food chain is weakened. The results derive from this study further demonstrate that, compare to tissues of liver and gonad, the fatty acids of muscle tissue can be more suitable to indicate the food source of oceanic fish species.

The extracellular enzyme activity of seawater can indicate the distribution characteristics of organic and the nutritional status of microorganisms. Activities of eight extracellular enzymes, including alkaline phosphatase, lipase, leucine aminopeptidase, chitinase, cellulose, xylosidase, α-D-glucosidase and β-D-galactosidase, were measured in the surface seawaters collected from 44 stations of the Yellow Sea and the East China Sea from March 25 to April 15, 2017 and from 10 stations of the Jiaozhou Bay nearby waters from April 28 to 29, 2018. In the spring of 2017, the high-value areas of alkaline phosphatase and lipase appeared in the northern coast of Jiangsu and the middle of the Yellow Sea, alkaline phosphatase activity and phosphate concentration were positively correlated. High activity areas of the other six enzymes (leucine aminopeptidase, chitinase, cellulose, xylosidase, α-D-glucosidase and β-D-galactosidase) appeared in the open sea outside the east of the Changjiang River Estuary. The average activities of β-D-galactosidase and xylosidase were significantly higher in the East China Sea than in the Yellow Sea. The decreasing order of average enzyme activities of the eight enzymes was as follows: alkaline phosphatase, lipase, leucine aminopeptidase, chitinase, α-D-glucosidase, β-D-galactosidase, cellulose, xylosidase, the values of α-D-glucosidase and β-D-galactosidase are proximate. The activities of alkaline phosphates, lipase and xylosidase in the Jiaozhou Bay nearby waters in spring 2018 decreased from nearshore to far shore. The decreasing order of the average enzyme activity of the eight enzymes was as follows: alkaline phosphatase, lipase, leucine aminopeptidase, xylosidase, α-D-glucosidase, β-D-galactosidase, cellulose, chitinase, the values of cellulose and chitinase are proximate. The alkaline phosphatase and lipase activities in the Yellow Sea were significantly higher than those in the East China Sea and Jiaozhou Bay. The average enzymatic activities of polysaccharide hydrolases (chitinase, cellulose, α-D-glucosidase, β-D-galactosidase and xylosidase) were the lowest in the Yellow Sea compared with those in the East China Sea and Jiaozhou Bay nearby waters. Our results are beneficial to understand the degradation of organic carbon by plankton and heterotrophic bacteria and the distribution of marine organic carbon in the coastal water of China.

Neon flying squid Ommastrephes bartramii is a short-lived cephalopod species whose abundance is highly susceptible to marine environmental changes and has large interannual fluctuations. Based on the statistical data from the squid fishery in the Northwest Pacific from 1995 to 2017, catch per unit effort (CPUE) was derived as an abundance index and the grey catastrophic prediction method was used to establish the GM（1, 1）model for the upper and lower catastrophic years and to forecast the future catastrophic years. The results show that the average relative error of the lower limit catastrophic prediction model established based on GLM-model-standardized CPUE is 15.32%, the average relative error of the upper catastrophic prediction model is 8.19%, and the accuracy tests for both models attain the level I accuracy. The study forecasts that the next upper catastrophic year may occur in 2021 (CPUE≥2.39 t/(ship·a)), and the lower catastrophe year occurred in 2027 (CPUE≤2.13 t/(ship·a)). The study also suggests that the Pacific Decadal Oscillation and El Niño-La Nina events are important factors driving large fluctuations in the squid abundance. The forecast can provide a reference for squid fishing enterprises and managing departments in the Northwest Pacific.