To better understand the community patterns mediated by connectivity in artificial reefs of coastal areas, it is necessary to understand the distribution and coexistence of organisms with artificial reefs area and adjacent waters. This study was conducted to examine main catches assemblages collected by trawls in Haizhou Bay, which included five habitats: the artificial reef area (AR), aquaculture area (AA), natural area (NA), estuary area (EA) and comprehensive effect area (CEA). The result shows that the total abundances of species in the five habitats were highly different (univariate PERMANOVA: P = 0.001, n = 24), but some species were also unique in their habitat (e.g. Scapharca subcrenata and Glossaulax didyma in AA). The body size distribution of specific species between habitats are different. For Collichthys lucidus, their body size in AR (14.63 cm ± 1.64 cm) and EA (14.3 cm ± 0.85 cm) is higher than that in NA (10.65 cm ± 1.64 cm), CEA (11.28 cm ± 1.85 cm) and AA (12.1 cm ± 0.43 cm), which indicates the potential connection from AR to EA mediated by their adult population. We concluded that artificial reefs in AR can be considered key components that have the ability to support species assemblages in adjacent habitats. This study has implications for the conservation and monitoring of species assemblages in coastal areas in terms of that artificial reefs can be applied in different stages of habitat protection implementation and in different combinations of scenarios.

With the development of ultra-wide coverage technology, multibeam echo-sounder (MBES) system has put forward higher requirements for localization accuracy and computational efficiency of ray tracing method. The classical equivalent sound speed profile (ESSP) method replaces the measured sound velocity profile (SVP) with a simple constant gradient SVP, reducing the computational workload of beam positioning. However, in deep-sea environment, the depth measurement error of this method rapidly increases from the central beam to the edge beam. By analyzing the positioning error of the ESSP method at edge beam, it is discovered that the positioning error increases monotonically with the incident angle, and the relationship between them could be expressed by polynomial function. Therefore, an error correction algorithm based on polynomial fitting is obtained. The simulation experiment conducted on an inclined seafloor shows that the proposed algorithm exhibits comparable efficiency to the original ESSP method, while significantly improving bathymetry accuracy by nearly eight times in the edge beam.

The tephra layers in multiple sediment cores from the offshore region of the Mahanadi basin in the northern Bay of Bengal were investigated for possible volcanic sources. The glass shards from those tephra layers were studied for size distribution, texture, and elemental geochemistry to establish chronostratigraphic markers for regional and global Quaternary correlation. The textural features of fine-grained (silty) volcanic glasses suggest the distal source of these tephra deposits. Major element composition with elevated SiO₂ contents ranging between 75%–76% and dominance of K₂O (> 4.5%) over CaO (< 0.9%) suggest ashes have originated from siliceous rhyolitic melts, similar to the petrographic composition of tephra from the Toba volcano. The bulk trace element compositions of the same glass shards were comparable with those reported in the youngest Toba tephra reported elsewhere. Likewise, the LREE-dominated chondrite normalized REE profiles of tephra from the Mahanadi basin closely resemble the characteristic REE patterns in Toba ash from other parts of the Indian Ocean and thus confirmed the contribution of the youngest Toba super-eruption for this ash layers.

High-resolution sea-level data and high-precision dating of corals in the northern South China Sea (SCS) during the Holocene provide a reference and historical background for current and future sea-level changes and a basis for scientific assessment of the evolutionary trend of coral reefs in the SCS. Although sporadic studies have been performed around Hainan Island in the northern SCS, the reconstructed sea level presents different values or is controversial because the indicative meaning of the sea-level indicators were neither quantified nor uniform criteria. Here, we determined the quantitative relationship between modern living coral and sea level by measuring the top surfaces of 27 live Porites corals from the inner reef flat along the east coast of Hainan Island and assessed the accuracy of results obtained using coral as sea-level indicators. Additionally, three in situ fossil Porites corals were analyzed based on elevation measurements, digital X-ray radiography, and U-Th dating. The survey results showed that the indicative meanings for the modern live Porites corals is (146.09 ± 8.35) cm below the mean tide level (MTL). It suggested that their upward growth limit is constrained by the sea level, and the lowest low water is the highest level of survival for the modern live Porites corals. Based on the newly defined indicative meanings, 6 new sea-level index points (SLIPs) were obtained and 19 published SLIPs were recalculated. Those SLIPs indicated a relative sea level fluctuation between (227.7 ± 9.8) cm to (154.88 ± 9.8) cm MTL between (5 393 ± 25) cal a BP and (3 390 ± 12) cal a BP, providing evidences of the Mid-Holocene sea-level highstand in the northern SCS. Besides that, our analysis demonstrated that different sea-level histories may be produced based on different indicative meanings or criteria. The dataset of 276 coral U-Th ages indicates that coral reef development in the northern SCS comprised the initial development, boom growth, decline, and flourishing development again. A comparison with regional records indicated that synergistic effects of climatic and environmental factors were involved in the development of coral reefs in the northern SCS. Thus, the cessation of coral reef development during the Holocene in the northern SCS was probably associated with the dry and cold climate in South China, as reflected in the synchronous weakening of the ENSO and East Asian summer monsoon induced by the reduction of the 65°N summer insolation, which forced the migration of the Intertropical Convergence Zone.

At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of He generation rate and the geochemical characteristics of the produced gas, both the similarities and differences between natural gas and He resources in the Bohai Bay, Ordos and the surrounding Songliao Basin are compared and analyzed, discussing the main controlling factors of helium resources in the three main petroliferous basins of the North China Craton. It is found that the three basins of Bohai Bay, Ordos and Songliao have similar characteristics of source rocks, reservoirs and cap rocks, that’s why their methane resource characteristics are essentially the same. The calculated ⁴He generation per cubic metamorphic crystalline basement in the three basins is roughly equivalent, which is consistent with the measured He resources, and it is believed that the ⁴He of radiogenic from the crust is the main factor controlling the overall He accumulation in the three basins; there is almost no contribution of the mantle-derived CH₄, which suggests that the transport and uplift of mantle-derived ³He carried by the present-day magmatic activities along the deep-large faults is not the main reason for the mantle-derived ³He mixing in the basins. Combined with the results of regional volcanic and geophysical studies, it is concluded that under the background of the destruction of North China Craton, magma intrusion carried a large amount of mantle-derived material and formed basic volcanic rocks in the Bohai Bay Basin and Songliao Basin, which replenished mantle-derived ³He for the interior of the basins, and that strong seismic activities in and around the basins also promoted the upward migration of mantle source ³He. This study suggests that the tectonic zone with dense volcanic rocks in the Cenozoic era and a high incidence of historical strong earthquakes history may be a potential area for helium resource exploration.

Acanthopagrus latus is an essential aquaculture species on the south coast of China. However, there is a lack of systematic breeding of A. latus, which considerably limits the sustainable development of A. latus. As a result, genetic improvements are urgently needed to breed new strains of A. latus with rapid growth and strong resistance to disease. During selective breeding, it is necessary to estimate the genetic parameters of the target trait, which in turn depends on an accurate disentangled pedigree for the selective population. Therefore, it is necessary to establish the parentage assignment technique for A. latus. In this study, 95 individuals selected from their parents and their 14 families were used as experimental material. SNPs were developed by genome re-sequencing, and highly polymorphic SNPs were screened on the basis of optimized filtering parameters. A total of 14 392 738 SNPs were discovered and 205 SNPs were selected for parentage assignment using the CERVUS software. In the model where the gender of the parents is known, the assignment success rate is 98.61% for the male parent, 97.22% for the female parent, and 95.83% for the parent pair. In the model where the gender of the parents is unknown, the assignment success rate is 100% for a single parent and 90.28% for the parent pair. The results of this study were expected to serve as a reference for the breeding of new varieties of A.latus.

The Oligocene Zhuhai sandstones are significant reservoirs for hydrocarbons in the Baiyun Sag, South China Sea. For effective appraisal, exploration and exploitation of such a deep-water hydrocarbon sandstone, samples of five wells from depths of 850 m to 3000 m were studied. A series of comprehensive petrographic and geochemical analyses were performed to unravel the diagenetic features and their impact on the reservoir quality. Petrographically, the sandstones are dominated by feldspathic litharenites and lithic arenites with fine to medium grain sizes and moderate to good sorting. The reservoir quality varies greatly with a range of porosity from 0.2% to 36.1% and permeability from 0.016 ×10^–3 μm² to 4301 ×10^–3 μm², which is attributed to complex diagenetic evolution related to sedimentary facies; these include compaction, cementation of calcite, dolomite, siderite and framboidal pyrite in eogenetic stage; further compaction, feldspar dissolution, precipitation of ferrocalcite and ankerite, quartz cements, formation of kaolinite and its illitization, precipitation of albite and nodular pyrite, as well as hydrocarbon charge in mesogenetic stage. The dissolution of feldspar and illitization of kaolinite provide internal sources for the precipitation of quartz cement, while carbonate cements are derived from external sources related to interbedded mudstones and deep fluid. Compaction is the predominant factor in reducing the total porosity, followed by carbonate cementation that leads to strong heterogeneity. Feldspar dissolution and concomitant quartz and clay cementation barely changes the porosity but significantly reduces the permeability. The high-quality reservoirs can be concluded as medium-grained sandstones lying in the central parts of thick underwater distributary channel sandbodies (>2 m) with a high content of detrital quartz but low cement.

Mozambique’s continental margin in East Africa was formed during the break-off stage of the east and west Gondwana lands. Studying the geological structure and division of continent-ocean boundary (COB) in Mozambique’s continental margin is considered of great significance to rebuild Gondwana land and understand its movement mode. Along these lines, in this work, the initial Moho was fit using the known Moho depth from reflection seismic profiles, and a 3D multi-point constrained gravity inversion was carried out. Thus, high-accuracy Moho depth and crustal thickness in the study area were acquired. According to the crustal structure distribution based on the inversion results, the continental crust at the narrowest position of the Mozambique Channel was detected. According to the analysis of the crustal thickness, the Mozambique ridge is generally oceanic crust and the COB of the whole Mozambique continental margin is divided.

The southwest Lahad Datu felsic rocks were previously thought to have formed in the late Triassic as part of the microcontinental crystalline basement. Based on U-Pb ages, geochemistry, and the Hf isotopes of zircon from the southeastern Sabah gabbro and granite, in this study, the tectonic properties of the Sabah area during the Triassic were investigated. The weighted average U-Pb zircon ages of the gabbro and granite samples were determined to be (230.9 ± 2.5)Ma and (207.1 ± 3.3)Ma, respectively. The granite had SiO₂ contents of 66.54%–79.47%, low TiO₂ contents of 0.08%–0.3%, Al₂O₃ contents of 10.97%–16.22%, Na₂O contents of 5.91%–6.39%, and low K₂O contents of 0.15%–0.65%. The chondrite-normalized rare earth element (REE) patterns exhibit light REE enrichment, with right-sloping curves. The primitive mantle-normalized trace element spider diagrams exhibit Th, U, La, Sr, and Zr enrichment and Nb, Ta, P and Ti depletions, i.e., the geochemical characteristics of typical island arc igneous rocks. The tectonic discriminant diagram indicates that the granite is a volcanic arc granite. The Hf isotopic analysis of gabbro zircon revealed that the zircons have ε _Hf(t) values of 12.08–16.24 (mean of 14.32) and two-stage model ages (t _DM2) of 223–491 Ma (mean of 347 Ma). This indicates that the diagenetic magma of the gabbro was mainly derived from melting of newly formed crustal materials. The ophiolite in southeast Sabah has existed since the early Late Triassic. The crystalline basement granite in southeastern Sabah was emplaced lasted from late Triassic to early Cretaceous. Based on previous studies and global plate reconstruction models, it is speculated that the southeastern Sabah granite may have been formed in an island arc setting, i.e., where the oceanic crust of the Paleo-Tethys Ocean collided with the oceanic crust of the Panthalassa Ocean.

The wave-induced liquefaction of seabed is responsible for causing damage to marine structures. Particle composition and consolidation degree are the key factors affecting the pore water pressure response and liquefaction behavior of the seabed under wave action. The present study conducted wave flume experiments on silt and silty fine sand beds with varying particle compositions. Furthermore, a comprehensive analysis of the differences and underlying reasons for liquefaction behavior in two different types of soil was conducted from both macroscopic and microscopic perspectives. The experimental results indicate that the silt bed necessitates a lower wave load intensity to attain the liquefaction state in comparison to the silty fine sand bed. Additionally, the duration and development depth of liquefaction are greater in the silt bed. The dissimilarity in liquefaction behavior between the two types of soil can be attributed to the variation in their permeability and plastic deformation capacity. The permeability coefficient and compression modulus of silt are lower than those of silty fine sand. Consequently, silt is more prone to the accumulation of pore pressure and subsequent liquefaction under external loading. Prior research has demonstrated that silt beds with varying consolidation degrees exhibit distinct initial failure modes. Specifically, a dense bed undergoes shear failure, whereas a loose bed experiences initial liquefaction failure. This study utilized discrete element simulation to examine the microscopic mechanisms that underlie this phenomenon.