Mesoscale eddies are one of the most prominent processes in the world’s ocean. The eddy-induced transport of water mass, heat, and energy has a great impact on the ocean and atmosphere. The study of global mass transport by mesoscale eddies is important. However, most existing studies have used Eulerian eddy detection methods. Compared with Lagrangian methods, Eulerian methods fail to distinguish the coherent transport from the incoherent transport induced by eddies. Using a Lagrangian-averaged vorticity deviation (LAVD)-based coherent eddy detection method, this study identifies global coherent mesoscale eddies in the upper 1000 m of the ocean. Based on the eddy dataset, the eddy-induced coherent mass transport is calculated. Compared with Eulerian estimates, the Lagrangian results shown in this study are one order of magnitude smaller. This means that roughly only about 10% of eddy-induced global water mass transport is coherent. The cumulative eddy-induced coherent transport across each latitude or longitude is only around 1 Sv (1 Sv ≡ 10⁶ m³ s⁻¹), which is much less than the transport induced by wind-driven gyres and thermohaline circulation.

Coastal dune sediments and landforms offer a unique opportunity to understand climate change and sea level change on the centennial-millennial time scale. However, there is a paucity of chronological studies on the effects of storms on the evolution of coastal dunes along the temperate coastline of China. In this study, optically stimulated luminescence (OSL) dating of sand dunes was conducted to investigate the process and mechanism of coastal dune evolution on the southeastern coast of Hainan Island, China. The results show that the coastal dune evolution experienced three rapid accumulation periods: 28-21 ka, 14-4 ka, and 3.0 ka-present. The three rapid accumulation periods correspond to the last glacial maximum, the late Pleistocene/early-mid Holocene, and the late Holocene climatic dry-cold period, respectively. Sea level change and the East Asian winter monsoon, in conjunction with the enhanced storminess, play a key role in driving the sand dune evolution on the south-eastern coast of Hainan Island. These findings are of great significance for regional planning and coastal defense schemes.

The coasts of Guangdong-Hong Kong-Macao Greater Bay Area (GBA) are facing threats and challenges from rising sea levels, frequent extreme events and human intervention. In this study, the Coastal Hazard Wheel (CHW) was used to classify the coasts of GBA, assess its hazard change from 2010 to 2020, identify hazards hotspots and explore available coastal management options. The results show that the coastal types of GBA in 2010 and 2020 are consistent, with delta/low estuary island and hard rock slope as the main types. GBA is vulnerable to ecosystem disruption, saltwater intrusion, gradual inundation and flooding hazards. Compared with 2010, the high risk proportion of each hazard in 2020 decreased significantly, but the high risk of flooding increased slightly. All kinds of hazards are interdependent and influenced by each other. The Pearl River Estuary, the east bank of Yamen Waterway, the west bank of Huangmao Sea and Dapeng Bay show very high hazard vulnerability, and the flooding risk is the highest. Soft measures such as coastal zoning, tsunami warning systems, wetland restoration and hazard simulation are most widely used in coastal management. CHW is applicable to GBA’s coastal hazard vulnerability assessment, which provides a case study for coastal risk assessment of GBA and has certain reference significance for hazard management and sustainable development for the Bay Area.

Among many coastal hazards, rip currents have gradually become one of the most noticeable hazards. Studies have demonstrated that most drowning accidents at beaches around the world are related to rip currents. In this study, online and field questionnaires were combined for the first time to reveal beachgoers’ awareness of rip currents in China from four aspects: demographic characteristics, swimming ability, information about visiting beaches, and knowledge about rip currents. One educational strategy was introduced to the field survey. The results suggest that (i) the proportion of online and field respondents who have heard of “rip currents” and seen warning signs of rip currents is extremely small. This reflects that beachgoers lack awareness of rip current hazards. Thus, China needs to strengthen the safety education of rip current knowledge. (ii) The level of awareness of rip currents can significantly affect the community’s ability to identify the location of rip currents and their choice of escape direction. (iii) In the field survey, we implemented an educational strategy as an intervention for respondents, and the accuracy of identifying rip currents and choosing the correct escape route improved by 34% and 46.7%, respectively. This implies that the intervention of educational strategy can significantly deepen beachgoers’ awareness of rip currents. It is recommended that more educational strategies about rip current knowledge be implemented on Chinese beaches in the future.

Research on the spatial and temporal distribution of shrimp mariculture can provide a reference for the optimization of the spatial distribution and sustainable development of the shrimp mariculture industry. In recent years, most of the domestic shrimp research focuses on biological characteristics, shrimp breeding, and environmental factors, with limited studies on the overall distribution patterns of large-scale marine shrimp farming.11 provinces along the coast of China were selected as the study area to investigate the spatial and temporal evolution characteristics of the four types of shrimp marine aquaculture production and their spatial differences in driving factors over the past 20 years. The results showed that: (1) The production and farming area of Litopenaeus vannamei (LV) were the highest among the four types of shrimp and increased exponentially over time. The farming area of the other three shrimp species showed a decreasing trend; (2) The farming centers of LV and Penaeus monodon (PM) are located in the southern regions, while those of Fenneropenaeus chinensis (FC) and Marsupenaeus japonicus (MJ) are in the northern regions. The farming centers of all four types of shrimp have shifted to varying degrees, with farming area being the main factor influencing the movement of these centers; (3) Regarding driving factors, wild catch, farming area, and extension personnel are the leading factors in the spatial differences in production, and the interaction between the factors ultimately led to spatial differences in shrimp production; (4) Comparison of different sea areas revealed that shrimp in the South China Sea region is mainly farmed in sea water, while the northern regions rely more on freshwater farming. The yield of shrimp per unit area in the South China Sea can reach up to 14 t/ha, which is significantly higher than that in the northern region; (5) Using the established regression model to predict the production and area of LV, its production and area in the next five years to maintain a sustained growth trend. The results can provide support for the formulation of relevant government policies, thus promoting the healthy development of shrimp mariculture.

The coupling mechanism between natural and anthropogenic noise in shallow marine areas is of great significance for maintaining the ecological safety of these regions. In this study, a section of Zhanjiang Bay’s entrance was selected as a typical research area, and environmental noise data at different depths were collected during the spring and autumn seasons. The spectral characteristics, sound pressure levels, and underwater noise frequency correlation matrices of environmental noise were analyzed to reveal the underwater noise characteristics of tidal channels in Zhanjiang Bay and their main influencing factors. The results show that underwater noise in this study area had a stable frequency band distribution. In the low-frequency range of 20–50 Hz, the main source of noise was the flow noise influenced by tides and topography, with a peak sound pressure level of approximately 97 dB. In the frequency range of 50 Hz to 500 Hz, the main noise sources were ships at sea, followed by wind-generated noise. At frequencies above 500 Hz, the noise intensity decreased. In addition, it was found that the sound pressure level in the low-frequency range had a significant correlation with the tidal level, increasing with the rise of the tide and decreasing during low tides. This study provides a research case on the impact that human noise activity has on environmental noise in shallow marine bays. These research findings can support the selection of sites and reduce construction noise from offshore wind farms, as well as ensure the acoustic ecological environment in the vicinity of marine ranches.