In this study, the activity range and distribution patterns of radium and radon isotopes in the coast sea of the Hongyanhe Nuclear Power Plant were investigated in autumn, 2017. The water ages were calculated by "Apparent Radium Age Model", which distribution was then used to assess the major direction of water transport in the study area. We also discussed the relationship between jellyfish abundance distribution and water transport direction. The results indicate that: (1) the activity ranges of ²²⁴Ra, ²²⁶Ra and ²²²Rn were 2.9−62.4 dpm/(100 L), 11.9−57.4 dpm/(100 L), and 0.1−1.3 dpm/L in the study area in autumn, respectively. (2) Based on the “Apparent Radium Age Model”, the so-calculated water ages were ranged from 0 to 16 d, with an average of (10.9±3.6) d. The major water transport direction was towards northeast with the velocity of 7.2 cm/s. (3) There was clear correlation between the distribution of jellyfish abundance and the major water transport direction. The higher jellyfish abundance was found in main water transport direction with older water ages.

Based on the survey data from the bottom-trawl surveys in Shandong coastal waters in autumn (October 2016), winter (January 2017), spring (May 2017) and summer (August 2017), the seasonal variations of population structure and spatial distribution of Cleisthenes herzensteini were studied. The results showed that the average length of C. herzensteini was larger in autumn and winter, while the average mass was larger in summer and autumn. When the length is more than 15 cm, the seasonal variation of mass is larger, and the growth rate of mass is the biggest in summer. The ages of C. herzensteini ranged from 1 to 5 years old, in which individuals of 1 and 2 years old accounted for 45.15% and 40.23% of the population, respectively. The parameters of the von Bertalanffy growth equation, L_∞, K and t₀, were 37.85 cm, 0.28 and −0.57, respectively. The Pauly empirical formula evaluated the natural mortality to be 0.54. The total mortality, the fishing mortality, the exploitation ratio, the age of first capture and the length of first capture were 1.69, 1.15, 68.05%, 1.48 years old and 12.68 cm, respectively. In each season, only the ratio of male to female in summer was significantly different from that in 1:1 (p<0.05), and the number of females was significantly higher than that of males. 50% of the length of sexual maturity is 22.35 cm. The highest ratio of sexual maturity and the highest average coefficient of sexual maturity occur in summer. C. herzensteini mainly distributes in areas with bottom water temperature of 6.45−19.06℃, bottom salinity of 31.82−33.10 and depth of more than 50 m. Its average catch in autumn is much more than that in other seasons, which declines sharply in winter and then rises slowly. The C. herzensteini in Shandong coastal waters showed some phenomena, such as narrow length distribution, deterioration of food supply, delayed spawning period and over-exploited stock. The resources changed dramatically before and after the forbidden fishing period.

Sexual reproduction of hermatypic corals for coral reef restoration has become a hot topic in recent years. In May 2018, the samples of Favia favus and Platygyra carnosus were collected from the water of Weizhou Island, Guangxi. All of them were cultured in laboratory and the fertilized eggs were collected. The early development process of embryos and larvae was observed and recorded. The results showed that F.favus and P.carnosus were both hermaphrodites, in vitro fertilization, and began to spawn on the fifth to eighth day after the full moon; the early development of embryos and larvae experienced the cleavage stage, blastula stage, gastrula stage and planula stage; the oocytes of two corals did not have zooxanthella as they were ejected. This study records the sexual reproduction behavior of reef-building corals in Weizhou Island, and provides a theory when using sexual reproduction for coral ecological restoration in the future.

Ocean acidification and warming are occurring globally through increasing CO₂ absorption into the oceans, and impose two serious and imminent threats to the persistence of scleractinian corals and the reef ecosystem they construct. To evaluate the effects of ocean acidification and warming on the early life stages of the reef-building corals Acropora austera and A. intermedia, their larvae were incubated at a full cross design of two temperatures (about 28℃, about 30℃) and pCO₂ (about 570 μatm, about 1 300 μatm) for 8 d. There were no significant differences in rates of settlement. Larval mortality rates of two reef-building corals were unaffected in any treatments. High pCO₂ significantly reduced post-settlement survival of A. austera but not A. intermedia, with a 25.87% reduction in post-settlement survival in high pCO₂ compared to control. Our results show that larvae settlement and mortality rates of the reef-building corals A. austera and A. intermedia were unaffected by ocean acidification and warming, and high pCO₂ are more detrimental to mortality rates of juvenile A. austera than high temperature. Different species of juvenile corals exhibit species-specific response to ocean acidification and warming, with important implications for coral recruitment and even species structure composition of reef-building corals in the future ocean.

In this study, we first used the spectral vegetation indices such as normalized difference vegetation index (NDVI), normalized difference water index (NDWI), atmospheric impedance vegetation index (ARPI) and visible spectrum slope ratio of coastal zone imager (CVSSR) to reconstruct the HY-1C coastal zone imager (CZI) image data of the Shankou mangrove national ecosystem nature reserve in Guangxi. And then, the minimum noise fraction rotation (MNF) was used to enhance the spectral difference between mangroves and general terrestrial vegetation on the reconstructed multi-band data set. We established a decision tree based on the MNF components to achieve automatic extracting mangrove information. The results show that the spectral indices reconstruction data and its MNF transformation can effectively enhance the difference between the mangroves and the general terrestrial vegetation on CZI images, the mangrove information can be effectively extracted by our decision tree. Compared with the experts’ interpretation results, the extracted accuracy of area of our method is over 90%. The overall detection accuracy is 88% after verification by random sample points.

Research on the structure and complexity of food webs helps to analyze the function, nutrient dynamics and energy conversion of food webs. Based on the survey data of fishery resources and the analysis of gastric contents in five voyages in Haizhou Bay and its adjacent waters from March to December 2011, this study constructed a Haizhou Bay topology network based on 11 topological network indices. To study the structure and complexity of the Haizhou Bay food network. The results showed that the number of species in the Haizhou Bay food network (S) was 93, the number of connections (L) was 1 021, the number of interactions per species (L/S) was 10.98, the number of connections (L/S²) was 0.12; the proportions of top species, intermediate species, foundation species were 29%, 69% and 2%, respectively; the omnivorous index of food web was 87%; the connection complexity index SC was 22.2; the characteristic path length ChPath was 2.11, and the clustering coefficient CC was 0.23. Studies on the number of interactions and the number of connections in each species showed that the values of L/S and L/S² were within the normal range, so the complexity of the Haizhou Bay food web remained high. Through the analysis of the structure of the food web by species ratio, omnivorous index, connection complexity index, characteristic path length and clustering coefficient, it was found that the food network structure of Haizhou Bay was in a stable state, and the proportion of basic species was low because the phytoplankton and seaweed groups were not classified. Through the study of the structure and complexity of Haizhou Bay food network, it provides an important basis for the in-depth study of the function of Haizhou Bay food network and the scientific management of Haizhou Bay fishery resources.

In order to assess the health status of ecosystem on the Changjiang River Estuary waters, the ichthyoplankton is used to be indicators. Selecting 10 evaluation indices, which are the total number of ichthyoplankton species, number of benthic species, number of column species, number of intolerant species, proportion of tolerant species, proportion of omnivores, proportion of insectivorous, proportion of carnivores, number of individuals in each sample, proportion of hybrid. This study calculates the estuarine biotic integrity index (EBI) value of the 1986, 1999, 2007 and 2016 by using 1, 3, and 5 approximation of value assignment, and assesses the change trend of the ecosystem health in the Changjiang River Estuary water in recent 30 years. The results show that in 1986, 1999, 2007 and 2016, the EBI values were 52, 40, 36 and 34, respectively, and the corresponding EBI levels were “good”, “fair”, “fair-poor” and “poor”, respectively. By analyzing the results of EBI annual changes, it was found that the health status of ecosystem in the Changjiang River Estuary in recent 30 years showed a trend of declining first and then maintaining at a low level, indicating that the ecosystem of the Changjiang River Estuary waters is urgent to carry out timely protection and restoration.

Some so-called circumglobal and/or circumpolar marine species are proved to be complexes of cryptic species with restricted distributions by molecular analyses. These phenomena imply that marine species diversity has been underestimated. In this study we use shell morphological characteristics together with mitochondrial COI and 16S rRNA gene sequences in order to study the taxonomy and to identify species of genera Cavolinia and Diacavolinia in family Cavoliniidae from the Indian Ocean and Northwest Pacific Ocean. Our results showed that the species delimitation of Diacavolinia is not supported by molecular analyses, those morphospecies (D. grayi, D. vanutrechti, D. pacifica, D. elegans, D. angulosa, etc.) with distinct morphology from northwestern Pacific are a single species, namely D. longirostris. The subdivision of subspecies and/or forms for C. uncinata could not be confirmed by DNA evidence. Phylogenetic analysis of COI revealed two independent geographical lineages for C. uncinata, C. globulosa and D. longirostris respectively, suggesting that these morphspecies may harbour cryptic diversity. Nuclear mitochondrial pseudogene sequences of COI were detected from most individuals of D. longirostris, which can affect the analysis of DNA barcoding.

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.

Micro plastics in sandy sediments collected from the intertidal zone of the offshore area of Qinhuangdao were floated by saturated NaCl solution and filtrated with membrane filter. Micro plastic particles were observed using microscope and infrared spectroscopy to discuss the origin and morphology. The surface morphology of micro plastics particles was characterized by scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) to analyze surface morphology and elements. The geo accumulation indexes (I_geo) and enrichment factors (EF) were used to study the pollution level and enrichment of heavy metals (Hg, Cd and Pb) in sandy sediments. Total organic carbon (TOC), total nitrogen (TN) and loss on ignition (LOI) and stable isotopes of carbon and nitrogen (δ¹³C and δ¹⁵N) in sandy sediments were determined in order to analyze the source characteristics. The results indicated that there were three types of micro plastics: fiber, foam and film. Fiber was in the majority of micro plastics. Micro plastic particles were enriched with Si, Al, Mg, Fe and Ca in the surface. Hg and Cd were seriously enriched, and Pb was not enriched in the sandy sediments. The concentrations of TOC and TN were low; TOC/TN ratio and stable isotopic composition of C and N (δ¹³C and δ¹⁵N) indicated that TOC originated from marine plankton algae.