Comparative analysis of climate-induced changes in distribution of representative fish species in the Yellow Sea.

Climate changes are posing remarkable impacts on marine fish and fisheries. Although many studies have addressed the distributional effects of climate change on single fish species or taxa in recent years, comparative studies focusing on different types of fish are still lacking. In this study, we applied dynamic bioclimate envelop models (DBEM), based on three earth system models, to predict sea surface and bottom temperature, as well as the spatial and temporal distribution of nine representative fishes in the Yellow Sea, contain two habitats, i.e., continental shelf benthopelagic (CBD) and continental shelf pelagic-neritic (CPN) fishes, and two thermophilies, i.e., warm temperate (WT) and warm water (WW) fishes. Under a low emissions scenario (RCP 2.6) and a high emissions scenario (RCP 8.5) between 1970 and 2060, results reveal that: a) CPN fishes show a distinct tendency to move to higher latitudes than CBD fishes, and WW fishes show a significant tendency to migrate more widely to the north than WT fishes; b) The relative abundance of CPN fishes is expected to be higher than that of CBD fishes, while there is no apparent difference in relative abundance between WW fishes and WT fishes. The main reasons for this difference are presumed to be: variance of temperature rise between the sea surface and bottom layers, divergent adaptations of the species, and disparate degrees of anthropogenic influence.

Large-scale assessment of exposure to legacy and emerging per- and polyfluoroalkyl substances in China's shorebirds.

Emerging per- and polyfluoroalkyl substances (PFAS) have become more widely applied, whereas legacy PFAS such as PFOS continue to distribute ubiquitously in the environment. Large-scale assessment of wildlife exposure to both emerging and legacy PFAS plays a key role in effective biomonitoring to better discriminate regional contamination patterns and provide early warnings. Using eggs of two closely-related shorebird species collected across China during the breeding season in 2021, we constructed contrasting PFAS levels and profiles in coastal versus inland populations. The highest ∑PFAS concentrations were found in two Kentish plover (Charadrius alexandrinus) populations from the Bohai Sea, a semi-enclosed shallow bay located in northeast China. These two populations showed exceptionally high PFOA concentrations (mean: 94 and 121 ng/g wet weight; West and North Bohai Sea, respectively) dominating the overall PFAS profile (66% for both). This pattern is characteristic, compared to that of other seabird eggs worldwide. By comparison, PFAS profile in the white-faced plover (Charadrius dealbatus) population at the South China Sea coast was dominated by PFOS (46%), which showed similar levels to those at the North Bohai Sea coast (mean: 29 and 20 ng/g, respectively). PFAS concentrations of Kentish plovers from the remote Qinghai Lake were lower compared to the three coastal populations, and were dominated by PFNA (mean: 2.6 ng/g, 29%) and PFOS (mean: 2.5 ng/g, 27%). None of the eggs analyzed in the present study exceeded estimated toxicity reference values for PFOS or PFOA. Additionally, the emerging 6:2 Cl-PFESA was detected in eggs from all regions, while its concentrations were highest in the Bohai Sea populations, and short-chain PFBS was only detected in the North Bohai Sea population. Our results indicate intensive local emissions of PFOA and emerging PFAS at the Bohai Sea region, and warrant further investigation and monitoring.

Global ocean contamination of per- and polyfluoroalkyl substances: A review of seabird exposure.

Per- and polyfluoroalkyl substances (PFAS) have been extensively produced and used as surfactants and repellents for decades. To date, the global contamination pattern of PFAS in marine biota has seldomly been reviewed. Seabirds are ideal biomonitoring tools to study environmental contaminants and their effects. Here, we compiled and synthesized reported PFAS concentrations in various seabird species to reflect spatiotemporal patterns and exposure risks of major PFAS on a global ocean scale. Perfluorooctane sulfonic acid (PFOS) was the most studied PFAS in seabirds, which showed the highest level in eggs of common guillemots (U. aalge) from the Baltic Sea, followed by great cormorants (P. carbo) from the North Sea and double-crested cormorants (P.auritus) from the San Francisco Bay, whereas the lowest were those reported for Antarctic seabirds. The temporal pattern showed an overall higher level of PFOS in the late 1990s and early 2000s, consistent with the phase-out of perfluorooctane sulfonyl fluoride-based products. Maximum liver PFOS concentrations in several species such as cormorants and fulmars from Europe and North America exceeded the estimated toxicity reference values. Systematic evaluations using representative species and long time-series are necessary to understand contamination patterns in seabirds in South America, Africa, and Asia where information is lacking. In addition, limited research has been conducted on the identification and toxic effects of novel substitutes such as fluorotelomers and ether PFAS (F-53B, Gen-X etc.) in seabirds. Further research, including multi-omics analysis, is needed to comprehensively characterize the exposure and toxicological profiles of PFAS in seabirds and other wildlife.

Climate change projections show shrinking deep-water ecosystems with implications for biodiversity and aquaculture in the Northwest Pacific.

The increased availability of environmental data with depth deriving from remote-sensing-based datasets permits more comprehensive modelling of the distribution of marine ecosystems in space and time. This research tests the potential of such objective modelling of marine ecosystems in four dimensions, spatial and temporal, to provide projections of how climate change may affect biodiversity, including aquaculture. This approach could be replicated for any regional seas. The Bohai Sea, Yellow Sea, and East China Sea (BYECS) are marginal seas in the Northwest Pacific bounded by China, Korea, and Japan. Despite providing important ecological and economic services, their ecological conditions and ecosystems distribution have not yet been systematically mapped. This analysis used 13 marine environmental variables, measured on a three-dimensional and monthly basis during 1993-2019, to classify and map the BYECS region by k-means clustering using cosine similarity as distance function. There were 13 distinct areas identified that fit the definition of "ecosystems" that is, enduring regions demarcated by environmental characteristics. Of these 13 ecosystems, the Yellow Sea Cold Water (YSCW) Ecosystem is significant in relation to seasonal species composition and the newly developing deep-sea salmon caging aquaculture in the region. Projections of the potential size of this water mass under various climate-change scenarios based on analysis using the Non-Parametric Probabilistic Ecological Niche (NPPEN) model show that its volume may decrease 31 %-66 % in the future. Such a decrease would have impacts on the seasonal species' abundances in the BYECS marginal sea region and threaten the deep-sea cold-water salmon farming.

Bibliometrics and visualization analysis of EwE model based on CiteSpace.

To explore the historical evolution and current status of the EwE (Ecopath with Ecosim) modelling research, the core dataset and extended dataset were collected by topic retrieval and citation indexing methods from the "Web of Science" from 1984 to 2020. The bibliometric analysis and mapping knowledge were performed by CiteSpace software, focusing on literature distribution, research forces, research theme, and hotspot evolution. The results showed that the annual publications in the EwE model researches were increasing, covering multi-disciplinary fields. Christensen, Walters, and Pauly were representative scholars with an important role in model development and relevant international cooperation. In the early stage, EwE model was usually applied to solve ecosystem problems, including spatial-temporal dynamic of structure and function, and the ecosystem effects of fisheries. Currently, marine resource management, ecosystem modelling, marine protected areas and ecosystem indicators had become the key themes. The research hotspots shifted from model development and food web structure to ecosystem forecasting and resource management, which would provide scientific evidence for ecosystem-based aquatic resource management and the construction of protected area in marine.

Modelling spatiotemporal trends in range shifts of marine commercial fish species driven by climate change surrounding the Antarctic Peninsula.

In recent decades, the relationships between species distributional shifts and climate change have been investigated at various geographic scales, yet there is still a gap in understanding the impacts of climate change on marine commercial fish species surrounding the Antarctic Peninsula. The dynamic bioclimate envelope model (DBEM) is a mechanistic model that encompass species distribution model and population dynamic model approaches to project the spatiotemporal change of marine commercial fish species driven by various climate change scenarios in the Southern Ocean. This paper focuses on the spatiotemporal changes of marine commercial fish species surrounding the Antarctic Peninsula under a high emissions scenario (RCP8.5) and a low emissions scenario (RCP2.6) from 1970 to 2060 following three different Earth System Models (ESMs), namely, the GFDL-ESM 2G, IPSL-CM5A-MR and MPI-ESM-MR. Results reveal that: i) The general latitudinal gradient patterns in species richness shifts poleward associated with a global abundance decrease ii) The Spp. richness in Eastern Antarctic Peninsula (EAP) is higher than in the Western Antarctic Peninsula (WAP) at the same latitude (>65°S latitude). iii) The reasons are that the krill-dependent predators in WAP could face a higher risk of depletion than that in EAP due to ocean warming and anthropogenic activities.

[Management of large marine ecosystem based on ecosystem approach].

Large marine ecosystem (LME) is a large area of ocean characterized by distinct oceanology and ecology. Its natural characteristics require management based on ecosystem approach. A series of international treaties and regulations definitely or indirectly support that it should adopt ecosystem approach to manage LME to achieve the sustainable utilization of marine resources. In practices, some countries such as Canada, Australia, and U.S.A. have adopted ecosystem-based approach to manage their oceans, and some international organizations such as global environment fund committee have carried out a number of LME programs based on ecosystem approach. Aiming at the sustainable development of their fisheries, the regional organizations such as Caribbean Community have established regional fisheries mechanism. However, the adoption of ecosystem approach to manage LME is not only a scientific and legal issue, but also a political matter largely depending on the political will and the mutual cooperation degree of related countries.

G-banding patterns of the chromosomes of amphioxus Branchiostoma belcheri tsingtauense.

Chromosome banding study remains lacking in amphioxus heretofore. This paper reports the G-band patterns of the metaphase chromosomes of amphioxus Branchiostoma belcheri tsingtauense, the first description and numbering of the karyotyped bands in a cephalochordate. G-banding results show that four out of the ten second pair chromosomes examined are heteromorphic, while the remaining ones (6/10) are homomorphic. In contrast, the other 17 pair chromosomes are all homomorphic. These broadly support our previous suggestion that the chromosomes No. 2 are a pair of sex-chromosomes. G-banding method stains positively 65.5% of the chromosome surface, and a total of 149 G-bands (77 positive, 65 negative and 7 variable) has been recorded in the 17 autosomes and the dimorphic chromosomes 2A' and 2A.

C-banding pattern and nucleolar organizer regions of amphioxus Branchiostoma belcheri tsingtauense Tchang et Koo, 1936.

Chromosome banding study remains lacking in amphioxus heretofore. This paper reports the C-band pattern of the metaphase chromosomes of amphioxus Branchiostoma belcheri tsingtauense, the first description of banded karyotype in cephalochordate. The C-banding showed that around 50% of the second chromosome pair examined was heteromorphic, while the remaining ones were homomorphic. In contrast, the other 17 pairs were all homomorphic. These broadly support our previous suggestion that the second chromosome pair is a pair of sex-chromosomes. The C-banding stained positively about 54.3% of the chromosome surface. Most of the centromeric and terminal regions in many chromosomes had positive C-bands, and some interstitial C-bands were also observed in some chromosomes. It seems clear that chromosomes of amphioxus are highly heterochromatinized. In addition, silver staining revealed a single pair of nucleolar organizer regions (NORs) located in the telomeric regions of medium-sized chromosomes. It is suggested that the number and location of NORs in amphioxus represent the primitive condition for chordates.

Evolution and expression of the amphioxus AmphiHMGB gene encoding an HMG-box protein.

Amphioxus HMGB gene, AmphiHMGB, encoding a high mobility group (HMG) protein was identified from the gut cDNA library of Branchiostoma belcheri tsingtauense. Primary structural examination indicates that it is a member of HMGB family. Molecular phylogenetic analysis suggests that AmphiHMGB represents the archetype of chordate HMGB genes including HMGB1, HMGB2 and HMGB3 although it may have lost its C-terminal domain during evolution. Northern blotting revealed that AmphiHMGB expression was restricted mainly to guts in the adult, and AmphiHMGB transcripts were in greater abundance in gastrula and neurula though they were markedly low in 1-day larva.