In recent years, the small pelagic fishery on the Pacific northwest coast of Mexico has significantly increased fishing pressure on thread herring Opisthonema spp. This fishery is regulated using a precautionary approach (acceptable biological catch (ABC) and minimum catch size). However, due to fishing dynamics, fish aggregation habits and increased fishing mortality, periodic biomass assessments are necessary to estimate ABC and assess the resource status. The Catch-MSY approach was used to analyze historical series of thread herring catches off the western Baja California Sur (BCS, 1981–2018) and the Gulf of California (GC, 1972–2018) to estimate exploitable biomass and target reference points in order to obtain catch quotas. According to the results, in GC, the maximum biomass reached in 1972 (at the beginning of fishery) and minimum biomass reached in 2015; the estimated exploitable biomass for 2019 was 42.2×10⁴ t; and the maximum sustainable yield (MSY) was 15.4×10⁴ t. In the western BCS coast, the maximum biomass was reached in 1981 (at the beginning of fishery) and minimum biomass was reached in 2017; the estimated exploitable biomass for 2019 was 3.2×10⁴ t; and the MSY was 1.2×10⁴ t. Both stocks showed a decrease in biomass over the past years and were currently near to point of full exploitation. The results suggest that the use of the Catch-MSY method is suitable to obtain annual biomass estimates, in order to establish an ABC, to know the current state of the resource, and to avoid overcoming the potential recovery of the stocks.

Chaeturichthys stigmatias and Amblychaeturichthys hexanema belong to the family Gobiidae, which are offshore warm fish species and widely distribute in the western Pacific Ocean. In this study, the mitochondrial cytochrome c oxidase subunit I (COI) sequences and 12S ribosomal RNA (12S rRNA) sequences were used to analyze the interspecific differences between the two species. The phylogenetic analysis showed that the interspecific distance was significantly higher than the intraspecific genetic distance. The Neighbor-Joining tree showed two separate clusters, without sharing haplotype. The mitochondrial genome sequence of C. stigmatias was also reported. This genome was 17 134 bp in size, with a high A+T content of 55.9%. The phylogenetic analysis based on the tandem 13 coding protein genes nucleotide sequences indicated that C. stigmatias showed a close relationship with A. hexanema. This study can provide the basic genetic data for two species and will help for constructing the phylogeny of the Gobiiade.

Cold seeps are pervasive along the continental margin worldwide, and are recognized as hotspots for elemental cycling pathway on Earth. In this study, analyses of pore water geochemical compositions of one ~400 cm piston core (S3) and the application of a mass balance model are conducted to assess methane-associated biogeochemical reactions and uncover the relationship of methane in shallow sediment with gas hydrate reservoir at the Makran accretionary wedge off Pakistan. The results revealed that approximately 77% of sulfate is consumed by the predominant biogeochemical process of anaerobic oxidation of methane. However, the estimated sulfate-methane interface depth is ~400 cm below sea floor with the methane diffusive flux of 0.039 mol/(m²·a), suggesting the activity of methane seepage. Based on the δ¹³C_DIC mass balance model combined with the contribution proportion of different dissolved inorganic carbon sources, this study calculated the δ¹³C of the exogenous methane to be −57.9‰, indicating that the exogenous methane may be a mixture source, including thermogenic and biogenic methane. The study of pore water geochemistry at Makran accretionary wedge off Pakistan may have considerable implications for understanding the specific details on the dynamics of methane in cold seeps and provide important evidence for the potential occurrence of subsurface gas hydrate in this area.

An introduced turbot population was used to establish families and to estimate genetic parameters of the offspring. However, there is a lack of pedigree information, and common environmental effects can be introduced when each full-sib family is raised in a single tank. Therefore, in the genetic evaluation, SSRs (simple sequence repeats) were used to reconstruct the pedigree and to calculate molecular relatedness between individuals, and the early mixed-family culture model was used to remove the impact of the common environmental effects. After 100 d of early mixed culture, twenty SSRs were used to cluster 20 families and to calculate paired molecular relationships (n=880). Additive genetic matrices were constructed using molecular relatedness (MR) and pedigree reconstruction (PR) and were then applied to the same animal model to estimate genetic parameters. Based on PR, the heritabilities for body weight and body length were 0.214±0.124 and 0.117±0.141, and based on MR they were 0.101±0.031 and 0.102±0.034, respectively. Cross validation showed that the accuracies of the estimated breeding values based on MR (body weight and body length of 0.717±0.045 and 0.629±0.141, respectively) were higher than those of PR (body weight and body length of 0.692±0.052 and 0.615±0.060, respectively). The MR method ensure availability of all genotyped selection candidates, thereby improving the accuracy of the breeding value estimation.

Nitrification is a key step in the global nitrogen cycle. Compared with autotrophic nitrification, heterotrophic nitrification remains poorly understood. In this study, Halomonas venusta MA-ZP17-13, isolated from seawater in shrimp aquaculture (Penaeus vannamei), could simultaneously undertake nitrification and denitrification. With the initial ammonium concentration at 100 mg/L, the maximum ammonium-nitrogen removal rate reached 98.7% under the optimal conditions including C/N concentration ratio at 5.95, pH at 8.93, and NaCl at 2.33%. The corresponding average removal rate was 1.37 mg/(L·h) (according to nitrogen) in 3 d at 11.2°C. By whole genome sequencing and analysis, nitrification- and denitrification-related genes were identified, including ammonia monooxygenase, nitrate reductase, nitrite reductase, nitric oxide dioxygenase and nitric oxide synthase; while no gene encoding hydroxylamine oxidase was identified, it implied the existence of a novel nitrification pathway from hydroxylamine to nitrate. These results indicate heterotrophic bacterium H. venusta MA-ZP17-13 can undertake simultaneous nitrification and denitrification at low temperature and has potential for ${\rm {NH}}_4^+ $-N/NH₃-N removal in marine aquaculture systems.

This study conducted four cruises during 2014–2017 to investigate relationships between macrobenthic communities and sediment contaminations in sea area around the Zhoushan Archipelago. Fourteen sites were categorized into three groups: high total heavy metal contamination content (HHMC), high total petroleum hydrocarbon content (HTPH), and low content ratio of heavy metal contamination content to total petroleum hydrocarbon content (HMC/TPH) areas. Four main taxa of macrofauna (polychaetes, bivalves, gastropods, and crustaceans) were determined to respond to environmental factors differently. While tolerant polychaetes being the minimal impact by environmental factors, bivalves were threated by heavy metal pollutions in sediment. Additionally, body size distribution frequency demonstrated that macrofauna in the low HMC/TPH areas were less disturbed by contamination than those in the HHMC and HTPH areas. The result represented the presentation of sensitive species while tolerant species are usually considered as small size organisms. Overall, this study confirmed the hypothesis that the contamination levels of small-scale patches is indicated by the condition of macrobenthic communities.

Growth and energy budget of marine amphipod juvenile Eogammarus possjeticus at different temperatures (20°C, 24°C, 26°C, 28°C, 30°C, 32°C and 34°C) were investigated in this study. The results showed that the cumulative mortality rate increased significantly with rising temperature (p<0.01), and exceeded 50% after 24 h when temperature was above 30°C. With the temperature increasing from 20°C to 26°C, the ingestion rate and absorption rate increased, but decreased significantly above 28°C (p<0.01), indicating a decline in feeding ability at high temperatures. The specific growth rate increased with rising temperature, but decreased significantly (p<0.01) after reaching the maximum value at 24°C. Similarly, the oxygen consumption and ammonia emission rates also showed a trend of first increase and then decrease. However, the O:N ratio decreased first and then increased with rising temperature, indicating that the energy demand of E. possjeticus juvenile transferred from metabolism of carbohydrate and lipid to protein. In the energy distribution of amphipods, the proportion of each energy is different. With rising temperature, the ratio of the energy deposited for growth accounted for ingested gross energy showing a trend of decrease, while the energy lost to respiration, ammonia excretion, and feces accounted for ingested gross energy being showed a trend of increase. It seemed that rising temperature increased the metabolism and energy consumption of the amphipods and, meanwhile, decreased the energy used for growth, which may be an important reason for the slow growth and small body size of the amphipods during the summer high-temperature period.

Spatial-temporal distribution of marine fishes is strongly influenced by environmental factors. To obtain a more continuous distribution of these variables usually measured by stationary sampling designs, spatial interpolation methods (SIMs) is usually used. However, different SIMs may obtain varied estimation values with significant differences, thus affecting the prediction of fish spatial distribution. In this study, different SIMs were used to obtain continuous environmental variables (water depth, water temperature, salinity, dissolved oxygen (DO), pH, chlorophyll a and chemical oxygen demand (COD)) in the Changjiang River Estuary (CRE), including inverse distance weighted (IDW) interpolation, ordinary Kriging (OK) (semivariogram model: exponential (OKE), Gaussian (OKG) and spherical (OKS)) and radial basis function (RBF) (regularized spline function (RS) and tension spline function (TS)). The accuracy and effect of SIMs were cross-validated, and two-stage generalized additive model (GAM) was used to predict the distribution of Coilia nasus from 2012 to 2014 in CRE. DO and COD were removed before model prediction due to their autocorrelation coefficient based on variance inflation factors analysis. Results showed that the estimated values of environmental variables obtained by the different SIMs differed (i.e., mean values, range etc.). Cross-validation revealed that the most suitable SIMs of water depth and chlorophyll a was IDW, water temperature and salinity was RS, and pH was OKG. Further, different interpolation results affected the predicted spatial distribution of Coilia nasus in the CRE. The mean values of the predicted abundance were similar, but the differences between and among the maximum value were large. Studies showed that different SIMs can affect estimated values of the environmental variables in the CRE (especially salinity). These variations further suggest that the most applicable SIMs to each variable will also differ. Thus, it is necessary to take these potential impacts into consideration when studying the relationship between the spatial distribution of fishes and environmental changes in the CRE.

This paper applies the narrow band Internet of things communication technology to develop a wireless network equipment and communication system, which can quickly set up a network with a radius of 100 km on water surface. A disposable micro buoy based on narrow-band Internet of things and Beidou positioning function is also developed and used to collect surface hydrodynamic data online. In addition, a web-based public service platform is designed for the analysis and visualization of the data collected by buoys. Combined with the satellite remote sensing data, the study carries a series of marine experiments and studies such as sediment deposition tracking and garbage floating tracking.

Saltmarshes are one of the most productive ecosystems, which contribute significantly to coastal nutrient and carbon budgets. However, limited information is available on soil nutrient and carbon losses via porewater exchange in saltmarshes. Here, porewater exchange and associated fluxes of nutrients and dissolved inorganic carbon (DIC) in the largest saltmarsh wetland (Chongming Dongtan) in the Changjiang River Estuary were quantified. Porewater exchange rate was estimated to be (37±35) cm/d during December 2017 using a radon (²²²Rn) mass balance model. The porewater exchange delivered 67 mmol/(m²·d), 38 mmol/(m²·d) and 2 690 mmol/(m²·d) of dissolved inorganic nitrogen (DIN), dissolved silicon (DSi) and DIC into the coastal waters, respectively. The dominant species of porewater DIN was ${\rm {NH}}_4^+ $ (>99% of DIN). However, different with those in other ecosystems, the dissolved inorganic phosphorus (DIP) concentration in saltmarsh porewater was significantly lower than that in surface water, indicating that saltmarshes seem to be a DIP sink in Chongming Dongtan. The porewater-derived DIN, DSi and DIC accounted for 12%, 5% and 18% of the riverine inputs, which are important components of coastal nutrient and carbon budgets. Furthermore, porewater-drived nutrients had obviously high N/P ratios (160–3 995), indicating that the porewater exchange process may change the nutrient characteristics of the Changjiang River Estuary and further alter the coastal ecological environment.