Understanding the spatiotemporal dynamics of marine megafauna is critical for ecosystem-based conservation and marine spatial planning. The East Asian finless porpoise (Neophocaena asiaeorientalis sunameri), an endangered coastal cetacean endemic to northern China, faces escalating anthropogenic pressures in its fragmented habitat. This study integrates dedicated boat-based surveys (2019–2024) with seasonal species distribution models using the Maximum Entropy (MaxEnt) algorithm to evaluate habitat suitability and identify drivers of distribution for this species in the Miaodao Archipelago, a priority candidate for China's national park system. Environmental variables were dimensionally reduced using season-specific principal component analyses to account for multicollinearity while preserving ecological interpretability. MaxEnt models exhibited robust predictive performance, emphasizing distance to aquaculture, distance to island, productivity gradients linked to chlorophyll —a concentrations, and distance to channel as key factors influencing East Asian finless porpoise habitat suitability. Spatial distribution patterns reveal marked seasonal variation: porpoises aggregated near islands and aquaculture zones during spring and autumn, shifted toward nearshore productive waters in summer, and moved offshore in winter to avoid coastal disturbances. The study highlights the necessity of integrating seasonal dynamics and human activity gradients into cetacean conservation frameworks. These findings support adaptive, seasonally responsive strategies such as regulating vessel traffic and promoting ecologically compatible aquaculture to enhance spatial management in the proposed national park. This establishes a template for evidence-based conservation in China's emerging national park system while advancing methodological frameworks for modeling highly mobile species in heterogeneous anthropogenic seascapes.

Understanding whether important habitats for mobile marine species remain spatially stable throughout the year is essential for effective conservation planning. For small coastal cetaceans inhabiting highly seasonal and human-dominated shelf seas, habitat use may reorganize substantially across seasons, potentially limiting the effectiveness of static spatial protection. Here, we investigated the seasonal dynamics and persistence of core habitats of the endangered East Asian finless porpoise (Neophocaena asiaeorientalis sunameri) in the coastal waters off Qingdao, China, using multi-year boat-based surveys conducted between 2018 and 2024. Seasonal kernel density estimation revealed pronounced spatial variation in porpoise distribution. Core habitats expanded during spring, summer, and autumn but contracted and shifted in winter. No areas functioned as year-round core habitat across all four seasons. Instead, habitat use showed strong seasonal turnover, with 61% of core areas occurring in only a single season. However, tri-seasonal core habitats persisted across three seasons and accounted for nearly one-quarter of the cumulative core habitat area, indicating spatially persistent areas of importance. Environmental comparisons showed that multi-seasonal core habitats were characterized by shallow nearshore waters and intermediate to relatively high net primary productivity, whereas winter core habitats occurred farther from shore and showed weaker productivity associations. These results indicate that important habitats are temporally dynamic rather than spatially fixed, highlighting how mobile marine species respond to seasonal environmental variability in human-dominated coastal ecosystems and why temporally explicit habitat assessments are needed to support conservation in dynamic seascapes.

Long-term dynamics and environmental drivers of large copepod communities remain poorly understood in river-influenced coastal ecosystems. Using monthly survey data from three periods spanning five decades (1959, 1982/1983, and 2011/2012), this study examined interdecadal changes in large copepod community structure and identified their environmental drivers in Laizhou Bay, Bohai Sea. Although the total abundance and biomass remained relatively stable among survey periods, the large copepod communities experienced pronounced structural reorganization, with dominance becoming increasingly concentrated in Calanus sinicus and Centropages abdominalis following the decline of the estuarine Labidocera euchaeta, and the emergence of Centropages dorsispinatus as the summer/autumn-dominant species. Seasonal biomass shifted from a balanced spring–summer/autumn structure to a spring-dominated structure owing to the collapse of the summer–autumn assemblage. Sea surface water temperature, Yellow River runoff, and PDO emerged as the principal drivers regulating seasonal succession, estuarine assemblages, and interdecadal variability, respectively, with reduced antecedent river discharge strongly associated with the decline of L. euchaeta. Distribution centers of L. euchaeta contracted and shifted with the relocation of the Yellow River mouth. These findings demonstrate that hydrological alteration and climate variability jointly reshaped large copepod community organization in these river-influenced coastal estuarine ecosystems.

Ecosystem integrity is the foundation of ecosystem health and is popular to quantitatively analyze ecosystem integrity using the Index of Biotic Integrity(IBI).The IBI was initially used as a water pollution index and has been widely applied in ecosystem health assessment,particularly in fish,benthos,and plankton.Phytoplankton is the primary producer in aquatic ecosystems and is sensitive to changes in environmental factors.The Phytoplanktonic IBI(P-IBI)has been increasingly used in the ecosystem health assessment of bays,rivers,lakes,and reservoirs.However,no reports are available on applying P-IBI in the estuary ecosystem.Based on P-IBI,this study constructed an ecological health assessment indicator system and built an evaluation criterion in the coastal waters of the Yellow River estuary.To evaluate the ecological health status,three surveys were conducted on phytoplankton in May,July,and December of 2020.A total of 31 sampling sites were set up in the study area(119°00′E-119°25′E,37°20′N-38°05′N),and 73 species of phytoplankton from four phyla were collected,with diatoms being the major groups and the species number accounting for 82.19％.The reference points and damaged points were determined according to the Shannon-Wiener diversity index H',and the sites with H'≥3 were reference points;the others were damaged points.Considering factors such as ecological characteristics of the study area,phytoplankton population distribution,and data availability,13 biological indicators were selected as candidate indicators.Then,the core indicators of P-IBI in various months were identified by screening candidate indicators.First,the discriminant ability analysis was used to preliminarily select the indicators,and their IQ ≥ 2 were retained.Second,Pearson correlation analysis was conducted for these indicators.The P-IBI core indicator system in May,July,and December contained four,five,and four biological indicators,respectively.The scores of each indicator were calculated using the ratio method.The 95％or 5％quantile of the core indicators in all sampling sites was regarded as the best expected value;for indicators which increased with increasing interference,the best expected value was 5％quantile.Conversely,for indicators which decreased with increasing interference,the best expected value was 95％quantile.Each indicator score was calculated using a different formula according to their response to interference.Accumulating all core indicator scores at the same site,the total P-IBI score for this site was obtained.The 25％quantile of the reference points P-IBI was taken as IBI-expected,the P-IBI range less than IBI-expected was quartered.The delineation standard for the ecological status grade was ascertained,and the ecological status level of each site was identified according to its total P-IBI.The ecological status of each site was marked by using 1,3,and 5 approximations of value assignment,the marked scores of each site were summed up using the equal weight method,and standardization was conducted to eliminate the differences caused by various indicator numbers.The comprehensive evaluation index(CEI)of the coastal waters in the Yellow River estuary was achieved.The results showed that the ecological status in each site was different and the spatial distribution was significantly diverse for the three months.In May,a few sites were present with excellent levels(9.68％),and they were scattered around the mouth of the Yellow River.In July,the proportion of sites with excellent levels reached 35.48％,and they were mainly located in the estuary of the Yellow River and Laizhou Bay.In December,the proportion of sites with excellent status was approximately 38.71％,and they were concentrated in the waters north of the Yellow River estuary.In general,concerning the stations above"good"ecological level,21 were present in May;29,in July;and 26,in December;therefore,the ecological condition was slightly worse in May.P-IBI had a significant positive correlation with ammonium(NH4-N),a significant negative correlation with nitrate(NO3-N),phosphate(PO4-P),and dissolved oxygen(DO),and a significant positive correlation with sea surface temperature(SST).However,no significant correlation was observed between P-IBI and sea surface salinity(SSS),pH value(pH),nitrite(NO2-N),and silicate(SiO3-Si).The CEI indicated the health status was"fair"in the coastal waters of the Yellow River estuary in 2020.Selecting reference points and screening biological parameters were the key steps in constructing the P-IBI indicator system,which determined the science of the evaluation result and the practicality of regional health management.The detailed method was offered in this study,and it could provide information for other research projects.This study provided a reference for the health management and ecological restoration of this water area and offered data support for the ecological protection and high-quality development of the Yellow River Basin.

IntroductionThe Yellow River estuary serves as a crucial convergence point between the Yellow River and the Bohai Sea and is a vital spawning, nursery, and feeding ground for a variety of fish species. Ichthyoplankton are essential for the replenishment and sustainable use of fishery resources. To gain insights into the distribution of fish in these early life stages and examine in depth the impacts of environmental factors on their presence and abundance in the waters around the Yellow River estuary, in this study, we analyzed the temporal and spatial distribution of ichthyoplankton and their correlation with environmental variables.MethodsData were gathered from horizontal-trawl surveys conducted between April and July of 2020, 2021, and 2023. In instances where no eggs or larvae were caught, a two-stage Generalized Additive Model (GAM) was employed to evaluate the influence of environmental factors on the presence/absence (P/A model) and abundance, given presence (Density model).ResultsThe results revealed that there were significant fluctuations in species richness both monthly and annually. Moreover, notable spatial disparities were identified in the distribution of abundance encompassing estuarine, settled, and migratory fish populations. The final model accounted for 38.69% and 39.80% of the deviance in the presence and abundance of ichthyoplankton, respectively. The two-stage GAM results highlighted that sea surface temperature (SST), chlorophyll a concentration, sea bottom salinity, and water depth were the dominant factors influencing the presence of ichthyoplankton. Moreover, a model incorporating SST, sea surface salinity, and distance to shore best described the abundance of ichthyoplankton when present.DiscussionOur findings contribute to understand the spatiotemporal dynamics of ichthyoplankton and their influencing factors in the waters around the Yellow River estuary, which have important implications for fisheries management.

The North Yellow Sea, once a vital habitat for diverse cetacean populations, has undergone significant ecological decline due to historical whaling, overfishing, and anthropogenic pressures. This study utilizes social media-derived data (2010-2024) and automated identification system (AIS) data from fishing vessels (2021-2024) to assess cetacean biodiversity, spatiotemporal dynamics, cetacean-fisheries interactions, and conservation challenges in this understudied region. Validating 90 records (over 170 individuals) from strandings, bycatch, and opportunistic observations, we documented only seven cetacean species-a stark 50 % decline in species richness compared to pre-1990s records. Spatial analysis revealed 83,385 fishing vessel positions (41.6 % of total) within 10 km of cetacean sightings (mean distance = 5.21 km), with significant hotspot overlap (Pearson's r = 0.185, p < 0.001). The East Asian finless porpoise (Neophocaena asiaeorientalis sunameri) dominated sightings (72.2 % of records), while historically abundant species like the fin whale (Balaenoptera physalus) were absent. Spatial clustering identified critical hotspots in the Changshan Archipelago and Dalian coastal waters, with peak activity in April-May. Fisheries bycatch, evidenced by direct vessel-cetacean co-occurrence (minimum distance = 0.39 km), emerged as the primary threat, while expanding aquaculture infrastructure and chronic vessel noise represent significant secondary pressures. Our findings highlight the urgent need for marine protected areas in identified hotspots, bycatch mitigation strategies (e.g., acoustic deterrents, gear modifications), and enhanced public engagement. This study demonstrates the efficacy of social media as a citizen science tool for monitoring cryptic marine megafauna in data-poor regions, offering actionable insights to reconcile conservation priorities with anthropogenic development.

The coastal wetlands of the Bohai Rim region in China serve as critical habitats for breeding, migratory stopovers, and wintering birds along the East Asian-Australasian Flyway. This study surveyed waterbird diversity across 17 coastal wetlands in the Bohai Rim region from 2018 to 2023 to identify community composition, analyze spatial and temporal patterns, and examine the key factors influencing waterbird diversity across various wetland types. A total of 133 species belonging to 18 families and 8 orders were recorded, with migratory species comprising 85.71% of the total. Scolopacidae, Charadriidae, and Laridae exhibited the highest species richness and abundance, respectively. The number of waterbirds and diversity indices displayed a fluctuating but overall upward trend during the study period. Estuarine wetlands had the highest waterbird diversity, tidal wetlands exhibited the greatest bird density, whereas shallow sea and island wetlands showed comparatively lower diversity and evenness. The primary factors influencing waterbird diversity, ranked by significance, were PM2.5 concentration, vegetation coverage, macrobenthic biodiversity, regional population density, and temperature. High PM2.5 concentrations were significantly associated with reduced waterbird diversity, whereas higher vegetation coverage promoted diversity by improving habitat complexity. Macrobenthic biodiversity influenced food web dynamics via predation and competition, leading to a marginally negative impact on waterbird diversity. Regional population density significantly impacted waterbird diversity in island and tidal wetlands, highlighting the necessity of establishing and managing protected areas to sustain waterbird diversity. Additionally, increased precipitation caused by climate change alters wetland water levels, indirectly impacting habitat conditions for waterbirds. Improved wetland management and pollution control are essential for preserving waterbird diversity. This study provides important insights into how air pollution, water pollution, and climate change affect waterbird diversity, emphasizing the importance of integrated management strategies for maintaining coastal wetland ecosystem stability and the health of waterbird communities.

In the realm of marine biodiversity conservation, understanding the dynamics between species' spatial distributions, habitat utilization, and human impacts is crucial. This knowledge is indispensable for marine spatial planning, facilitating the identification and mitigation of conflicts between human activities and the conservation goals of marine ecosystems. The East Asian finless porpoise (Neophocaena asiaeorientalis sunameri), classified as endangered by the IUCN Red List, is the only cetacean routinely observed in the vicinity of the Miaodao Archipelago. To identify key areas for this species and assess the impact of human activities, boat-based surveys were conducted from 2019 to 2023, covering 6220 km2 of the Miaodao Archipelago's waters. These surveys recorded 1610 porpoise sightings over 75 survey days. Spatial analysis revealed that the East Asian finless porpoises primarily frequent three core density areas characterized by high sighting densities. Additionally, intermediate density and habitat range areas were delineated, which are essential for the porpoises' movement between these core regions. The study also analyzed the spatial usage of porpoises within and outside areas affected by human activities, revealing that sighting densities were significantly higher in regions with minimal human impact (p < 0.01). Based on these findings, it is proposed that the areas with high porpoise sighting densities be managed as a unified protected area network. These findings should guide future conservation and management strategies within the National Park to ensure the effective preservation of this endangered species.

In this study, we examined the short-term variation in the abundance of copepod Acartia specimens, identified previously as Acartia pacifica, in Laizhou Bay, an estuarine bay in the southern Bohai Sea in northern China. Monthly samples were collected from May 2011 to April 2012, excluding December 2011 and January to February 2012 due to ice. Based on its morphological characteristics, Acartia ohtsukai was distinguishable from A. pacifica for the first time in Laizhou Bay. A. ohtsukai was sporadically present from summer to autumn, with the highest abundance and occurrence in September. It appeared in June when the water temperature was above 20°C, and disappeared in November when the water temperature decreased to less than 10°C. During the surveyed months, A. ohtsukai was more commonly found inshore with salinity less than 28 than offshore in the bay. Correlation analysis revealed that temperature and chlorophyll a concentration significantly influenced the monthly variations in A. ohtsukai abundance. We also compared the occurrence of A. ohtsukai with that of three species from the genus Tortanus (Tortanus derjugini, Tortanus forcipatus, and Tortanus spinicaudatus) in Laizhou Bay. The coexistence of A. ohtsukai and T. derjugini in the bay suggests that their ecological habitats are similar to those of brackish-water species.

Dryinidae is a cosmopolitan wasp family, with over 1900 species found worldwide [...]

This study was aimed at investigating the viral diversity associated with marine organisms in the South China Sea, to improve understanding of the region’s viral ecosystems. Viruses profoundly influence aquatic ecosystems, by affecting marine biogeochemical cycles and posing threats to marine organisms. Nonetheless, a comprehensive study of marine organisms’ viral diversity in the South China Sea remains lacking. We collected gill and viscera tissue samples from three marine phyla ( Chordata , Arthropoda , and Mollusca ) along the South China Sea coast. High-throughput sequencing and bioinformatics analyses were conducted to identify and characterize viral communities within these samples, with a focus on both viral composition and potential zoonotic threats. We observed distinct viral composition patterns across tissues and phyla, notably involving Adintoviridae and viruses within the Herpesviridae and Dicistroviridae . The presence of zoonotic viruses in economically important aquatic organisms suggests potential risks. This study contributes to broader understanding of viral diversity, by suggesting potential epidemic causes and illustrating genetic relationships among viruses associated with marine organisms. By extending the virus distribution map for this region, our findings underscore the need to consider the viral microenvironments surrounding marine species, and their implications for marine and human health.

1. The East Asian finless porpoise (Neophocaena asiaeorientalis sunameri) distributes in coastal waters across the western Pacific Ocean, ranging from the Taiwan Strait to northern China, Korea and Japan. Limited baseline data are available for this threatened species, including the coastal region of Qingdao, China, hindering the implementation of conservation management. 2. The Oceanographic characteristics were derived from on-board measurements and satellite remote sensing, including depth, slope, sea surface temperature (SST), salinity and chlorophyll a (Chla) concentration. Kernel density estimation (KDE) was utilized to determine the extent of occurrence and core distribution of East Asian finless porpoises. 3. The surveys covered an area of 4532 km(2), encompassing 7314 km of transect lines. The 95% KDE and 50% KDE for East Asian finless porpoises within the study site included 1987 and 297 km(2), respectively. The 50% KDE revealed Laoshan Bay as the core distribution zone. Significant relationships were identified between distribution probability and three oceanographic variables: salinity, Chla concentration and distance to shore. 4. In this study, the Aoshan Bay Marine Park, which was designed with no prior knowledge of East Asian finless porpoise, shows partial overlap with the core distribution for this species. This demonstrates that MPAs (marine protected areas) that are not explicitly designated for marine mammals may not comprehensively address all their specific requirements, but the existence and conservation endeavours associated with the MPAs can still yield substantial positive outcomes for these species. 5. This study provides the inaugural comprehensive baseline data on the population distribution and habitat characteristics of the East Asian finless porpoise. It underscores the necessity for a robust data collection protocol spanning China, Japan and Korea to address the critical shortfall in baseline data and enhance conservation efforts.

Acartia hongi is an endemic brackish and coastal copepod species in the Yellow and Bohai Seas. To investigate the population structure and distribution, we examined samples of A. hongi copepodites from May 2011 to April 2012, excluding the ice season. A generalized additive model (GAM) was used to explore the response of the abundance and prosome length (PL) of A. hongi to a range of environmental variables, including temperature, salinity, chlorophyll a (Chl a) content, Yellow River runoff, pelagic fish, and phytoplankton. A. hongi occurred throughout the survey season continuously and area widely in Laizhou Bay. It was a dominant species in the copepod community and showed a maximum abundance during April and May. The CI-CIII copepodites were the primary contributors to the total population of A. hongi during the blooming months. Population densities (>10,000 ind.m(-3)) occurred in nearshore waters with temperatures between 10 degrees C and 15degree celsius and salinities between 25 and 27. Mean PLs across all copepodite stages were shortest in August or September and longest in March. The best-fitting GAMs for copepodite abundance and PL included the variables of temperature, salinity, Chl a content, and runoff. The abundance of A. hongi copepodites decreased with increasing temperature, particularly for CI and CII copepodites, when the temperature exceeded 10-15degree celsius. Salinity and runoff showed more negative correlations with A. hongi copepodites of younger stages. The PLs across the copepodite stages demonstrated significant inverse correlations with temperature. Furthermore, the Chl a content significantly influenced the PLs of CVs and adults through interactions with temperature. Overall, this study highlights temperature as a critical factor for the abundance and size distribution of the A. hongi population. Copepodites at earlier stages are more sensitive to temperature and salinity fluctuations. These findings provide valuable insights into the environmental effects on the A. hongi population dynamics in Laizhou Bay.

The Yellow River estuary is one of the three largest estuaries along the coastal waters of China, along with the Yangtze and Pearl River estuaries. Its adjacent seawaters are rich in biological resources, with abundant fish habitat, spawning grounds, and migration channels in the Bohai Sea and the Yellow Sea. However, as the waters are too shallow for a survey ship, data was insufficient for research in the intertidal zone of the salt and freshwater interchange. Instead, by interviewing and analyzing the daily catches by the set net of the local fishermen, this study explored the fishery biodiversity in the intertidal zone of the Yellow River estuary from April to November 2020. Yellow River estuary is rich in fishery resources, especially small fishery organisms and fish recruitment stocks. There were monthly variations in the dominant species composition and biodiversity index. A total of 61 species were recorded, most of which were fish and crustaceans. The diversity, evenness, and species richness index increased in summer（July and August） and decreased in autumn（October and November）. By cluster analysis of the species compositions, the surveyed months can be divided into two groups: May to September, and October to November. Lateolabrax maculatus and Liza haematocheila were the most common and dominant species in all surveyed months. The main contributors to the catch of each month were: snails from April to July,snails and fish in August, fish in September, and crabs from October to November. Catches by the set net were mainly composed of individuals with body mass ＜2 g from April to September. From body mass-frequency distributions, fish with body mass ＜10 g were the main contributors to total catches from April to September. The mean body mass of fish in all surveyed months was 13 g/ind.. The dominant fish species with body mass with ＜20 g were: Gobioidei in April; L. maculatus in May; Konosirus punctatus in June; Pennahia argentata, Gobioidei, and L. haematocheila in June to August; and Sardinella zunasi,Thrissa kammalensis, T. mystax, Sillago sihama, Tylosurus melanotus, Gobioidei, and L. haematocheila in September. From the above results, the local set net fishery survey proved to be an effective method of collecting fishery data in the intertidal zone and can be incorporated in studies considering the distribution of fishery resources and breeding grounds in the seawaters adjacent to estuaries. In addition, this study provided clear evidence that set net fishing practices could severely impact the natural recruitment and stock enhancement of fish resources due to the low selectivity of nets and the overlap with larval fish migration channels. The number of larval fish captured by the set net fishery was, roughly estimated,several times higher than the local enhancement released. To minimize the effects of net mesh size,considering the spatial-temporal distributions of fish larvae, set net fishing practices should be concentrated to summer and early autumn, though further research is required to comprehensively account for both the protection of fishery resources and livelihoods.

Once an important cetacean habitat, the Miaodao Archipelago has been altered by human-induced disturbances over several decades. While cetacean diversity is known to have decreased, no recent data on species diversity around Miaodao are known to exist. Capitalizing on the high vocal activity of cetaceans, three passive acoustic surveys, including towed and stationary types, were undertaken to detect the presence of species-specific vocalizations in May 2021, October 2021, and July 2022, as most cetacean sightings occurred during May and August in recent years. The results revealed that the East Asian finless porpoise is the sole cetacean species that can be reliably observed around the archipelago, as no other species were detected. The acoustic data also revealed potentially clumped distributions of finless porpoises with some seasonal variation. While not acoustically detected during any of the surveys, humpback whales, minke whales, and killer whales have been visually sighted in the region. The lack of acoustic detection of these species suggests that they are likely to be temporary visitors to the region, or at least exhibit strong seasonality in their presence within the region. These new data provide the latest snapshot of cetacean presence around the Miaodao Archipelago that can help inform future research and conservation.

The baseline data pertaining to the population of the East Asian finless porpoise (Neophocaena asiaeorientalis sunameri) in Chinese waters are significantly deficient. Boat-based visual line transect surveys were conducted from 2018 to 2020 to evaluate the distribution and abundance of the East Asian finless porpoise in the coastal waters (depth < 30 m) of the Yellow Sea, with a specific focus on the Shandong Peninsula. A total of 50 transects covering 2705 km were conducted, encompassing an area of 23,604 km2 between 119°30′ E–123°15′ E and 35°25′ N–38° N. Throughout the surveys, a total of 117 East Asian finless porpoise groups were detected, with over 90% of these groups occurring within 15 km of the coast or adjacent islands. The estimated abundance of the East Asian finless porpoise in the study area was determined to be 3978 individuals (CV = 22.39%, 95%CI = 2561–6177), reflecting a low density of 0.169 individuals/km2 (CV = 22.39%, 95%CI = 0.109–0.262) within the coastal waters of the Yellow Sea in the Shandong Peninsula. The findings highlight the need for conservation measures to address the threats faced by this species, including bycatch, habitat degradation, and pollution. The establishment of marine protected areas and the implementation of bycatch mitigation measures are crucial for the long-term survival of the East Asian finless porpoise population in the study area. By providing valuable data on the distribution and abundance of the East Asian finless porpoise, this study contributes to our understanding of the population dynamics and conservation status of this threatened species in the Yellow Sea of the Shandong Peninsula.

Marine stock enhancement is not only commonly reported to amplify the target species production but also induces some potential threats or effects at multiple ecological levels in the receiving ecosystem. Studies on the interaction between released and naturally occurring organisms are necessary to avoid or minimize the adverse impacts of invasive species from stock enhancement in the receiving system. Chinese shrimp Fenneropenaeus chinensis, are an important stock enhancement species, and in recent years approximately 10 billion have been released annually into the coastal waters of China. Owing to fishing pressure and the ecological complexity of the open sea, the interaction between the released shrimp and native species may be weak and undetectable. Studies on the ecological impacts of such intensive releasing activities are limited. Therefore, in this study, an in-situ mesocosm experiment was carried out to determine if the released shrimp altered the relative composition and niche characteristics of fish, the results of which could serve as a reference to the local risk management of the species stock enhancement. The mesocosm was located in the shrimp-releasing channel of Weihe, Laizhou Bay, from April to September 2019. A cross design of four treatments with three replicates was conducted in the mesocosm. The habitats were homogenized across the replicates by mixing substrates and filtering seawater with a 0.28 cm sieve. The number of individual shrimp larvae released into net enclosures in each of the four treatments were: A) 2 400, B) 1 800, C) 1 200, and O) 0. The treatments were designed to represent the release of 1 billion, 750 million, 500 million, and no shrimp larvae (none-releasing) in the coastal waters of Laizhou Bay, respectively. The released shrimp larvae had an average body length of (1.63±0.18) cm and an average body width of (0.38±0.12) cm. At the end of the experimental period in September, shrimp and fishes were recaptured and their Levin's niche breadth and overlap indices were examined in each enclosure. Results indicated that within the enclosures of the four treatments, the recapture rates of shrimp ranged from 8.16% to 12.69% and had an average value of 9.87%. The number of recaptured shrimp increased with the number released, and had the highest value in enclosure A. However, the total biomass, average individual mass, and recapture rate of shrimp did not show a similar pattern among enclosures. The recapture rate of shrimp was significantly different among the treatments and had the highest value in enclosure C. The fish species composition was similar across all four treatment enclosures and included six species with three different feeding habits: Omnivores (Konosirus punctatus and Liza haematocheila), zooplanktivores (Thryssa mystax and Sardinella zunasi), and fish/shrimp predators (carnivores) (Acanthogobius sp. and Sparus microcephalus czerskii). Of the fish species, Acanthogobius sp. dominated in all enclosures, while S. m. czerskii occurred in only a few. There was no significant difference in the number and biomass of total fishes and carnivorous fishes among enclosures. There were more omnivorous fishes in the released enclosures A–C, while the number of zooplanktivorous fishes decreased when shrimp were released and had the highest number and biomass in the non-released enclosure O. Moreover, fishes with different feeding habits had variable niche breadths among the four treatment enclosures. Most fish species had a wider niche breadth in enclosures with released shrimp (enclosure A–C) than in enclosure O. Both the fish´s niche overlap indices and the species pairs with high niche overlap (> 0.75) decreased in the order non-released enclosure O > released enclosure B > enclosure C > enclosure A. The carnivorous fish Acanthogobius sp. had more pairs with niche overlap indices (> 0.75) in the non-released enclosure O than in the other three treatments. A similarity analysis and multidimensional plot indicated that enclosures A and O could be differentiated by the relatively long similarity distance and little overlap area. The results of the experiment suggest that the shrimp recapture efficiency did not increase when shrimp were released. In the waters of the study area, released shrimp could have a positive effect on the total output of both shrimp and fish, especially for omnivorous and carnivorous fishes, as the shrimp could share predation pressure and provide food for them. In addition, the shrimp release may affect the relative composition and niche characteristics of fish by increasing their niche breadth and reducing the overlap between fishes with different feeding habits, and the impacts may be more detectable as the shrimp number increases.

构建黄河口近岸水域鱼类生物完整性指数(F-IBI)评价指标体系,可为河口典型渔业水域的生态修复和渔业资源可持续利用提供科学参考.基于2020年黄河口近岸水域鱼类资源底拖网调查,分别以1982-1983年和2013-2014年的调查数据为参照点,从种类组成与丰度、繁殖共位群和营养结构等方面筛选14个评价指标,构建黄河口近岸水域F-IBI评价指标体系,采用1、3、5赋值法计算鱼类生物完整性指数,用以评价黄河口近岸渔业水域健康状况.结果显示,与20世纪80年代初相比,黄河口近岸水域鱼类生物完整性水平为"差";与2013-2014年相比,鱼类生物完整性水平为"好".相较于20世纪80年代初,近40年来黄河口近岸水域生态健康状况下降严重,处于较差的水平;但与2013-2014年相比,2020年黄河口近岸水域生态健康状况变化不明显.过度捕捞、环境污染、入海径流量锐减等因素致使黄河口鱼类栖息环境恶化,资源结构被破坏,生物完整性降低,生态健康状况下降.

长岛海域是黄渤海东亚江豚(Neophocaena asiaeorientalis sunameri)的热点分布区域之一.为了掌握长岛海域东亚江豚的种群密度与分布特征,2019年10月至2021年10月采用截线抽样法进行了5次东亚江豚目视考察.5次考察总航程2 421 km,共发现东亚江豚614次,1 156头次.相同月份调查种群遇见率无显著性差异(P＞0.05),不同月份种群遇见率差异极显著(P＜0.01),提示东亚江豚种群在该水域可能存在季节性迁移.按照考察月份对数据进行合并处理,长岛海域5月和10月东亚江豚平均种群密度为(0.56±0.11)头/km2(0.46～0.68头/km2)和(3.63±0.25)头/km2(3.38～3.88头/km2),平均种群数量为(20 209±202)头和(2 971±681)头,这在目前己知所有东亚江豚分布区中是最高的.尽管不同季节种群数量差异显著,但东亚江豚种群在长岛海域的空间分布特征相似,砣矶岛-大钦岛西北侧和东南侧均为高密度分布区,因此建议将该水域作为核心区域重点保护.此外,我们还建议未来加强对其迁移规律及栖息地选择的研究.

The Shandong Peninsula is located on the western coast of the Pacific and is adjacent to the Bohai Sea (BS) and the Yellow Sea (YS) to the east. The East Asian finless porpoise Neophocaena asiaeorientalis sunameri, a subspecies of the narrow-ridged finless porpoise N. asiaeorientalis, is the dominant cetacean resident along the Shandong Peninsula. However, there is insufficient monitoring data to determine the status of the cetacean species in this region. Based on the publicly available literature, media, and internet social website, this study investigated the spatial–temporal distribution of porpoise stranding and bycatch along the coast of the Shandong Peninsula. Data on over five hundred porpoises from two hundred reports between 2000 and 2018 were compiled and analyzed. Results showed that the bycatch and stranding of porpoises occurred widely across the peninsula throughout all months and increased rapidly between 2010 and 2017. The incidents were more frequent in the area where the BS and YS converged during the spring and early summer than in other seasons. The mean body length of bycaught porpoises was smaller than that of those found stranded. Fishing activities could be the principal cause of local finless porpoise incidents. However, limited data hindered a quantitative evaluation of the living conditions of finless porpoises in this area. Establishing a comprehensive monitoring system, which includes standardized reporting, rescue operations, and scientific research, is essential to finless porpoise protection along the Shandong Peninsula.