Search Results (14)

The mud crab (Scylla paramamosain), also known as the mangrove crab, thrives in shallow mangrove forests, subtidal zones, and muddy intertidal habitats. It is a highly valuable species in the mangroves and estuaries of tropical regions and is in high demand in Vietnam’s coastal markets. This study provides a comprehensive analysis of the key factors influencing consumer behavior and purchasing decisions regarding mud crabs in Vietnam’s three largest cities: Can Tho City, Ho Chi Minh City, and Hanoi Capital. To achieve this, the research employs rigorous analytical methods, including Cronbach’s alpha reliability test, principal component analysis, and multivariate regression analysis, to identify the primary determinants of consumer behavior and purchasing preferences for fresh mud crabs. The multiple regression analysis reveals two key factors that significantly influence consumer choices: nutritional knowledge and convenience awareness. Most of consumers perceive fresh mud crabs as superior in quality, expecting them to offer greater freshness; higher levels of protein, amino acids, and minerals; as well as excellent flesh texture and enhanced palatability. Based on these findings, two strategic directions are proposed for the sustainable development of Vietnam’s crab industry: (1) improving the nutritional quality of crab products to align with consumer expectations for health benefits and (2) enhancing the distribution network and diversifying product offerings to improve accessibility and convenience for consumers. Full article

Located within the subpolar front (SPF) zone, the eastern coast of Korea is subject to frequent environmental changes on both spatial and temporal scales. In this study, we analyzed seasonal changes in the algal community structure and related environmental factors at two sites, Chodo (CD) and Sageunjin (SG), which were influenced by cold and warm-water masses, respectively, in the SPF zone. Sea surface temperature (SST) exhibited greater seasonal change in CD, whereas significant wave height was higher in SG. The salinity and nutrient concentrations decreased during summer and increased in winter at both sites. Seasonal shifts in the dominant species were distinct, with turf species positively correlated with SST dominating the intertidal zone of SG during winter, and canopy species were associated with nutrient concentrations dominating the intertidal zone of CD. Bryopsidales, which was positively correlated with the N:P ratio, dominated the SG subtidal zone in summer, whereas Fucales, which was positively correlated with the SST, dominated the CD subtidal zone. These results enhance our understanding of seaweed responses to environmental changes in SPF zones and provide a basis for predicting future changes in coastal ecosystems. Full article

Benthic microbial communities are a vital component of coastal subtidal zones, playing an essential role in nutrient cycling and energy flow, and are fundamental to maintaining the stability and functioning of marine ecosystems. However, the response of benthic prokaryotic and eukaryotic microbial communities to environmental changes remains poorly understood. Herein, we conducted a nearly semimonthly annual sampling survey to investigate the temporal patterns and underlying mechanisms of benthic prokaryotic and eukaryotic microbial communities in the subtidal sediments of Sanshan Island, situated in the eastern Laizhou Bay of the Bohai Sea, China. The results showed that the temporal variations in benthic microbial communities followed a distinct seasonal pattern, with turnover playing a more dominant role in community succession. Nonetheless, contrasting temporal variations were observed in the alpha diversity of benthic prokaryotic and eukaryotic microbial communities, as well as in the dominant taxa across different microbial communities. Water temperature, dissolved oxygen, electrical conductivity, salinity, total nitrogen (TN), NH₄⁺, and PO₄³⁻ were identified as the predominant environmental drivers. The assembly of benthic microbial communities was driven by different ecological processes, in which stochastic processes mainly shaped the benthic prokaryotic communities, while deterministic processes dominated the assembly of benthic eukaryotic microbial communities. Interactions within benthic microbial communities were primarily characterized by mutualistic or cooperative relationships, but the ability of prokaryotic and eukaryotic microbial communities to maintain stability under environmental disturbances showed notable differences. These results shed light on the temporal dynamics and potential driving mechanisms of benthic prokaryotic and eukaryotic microbial communities under environmental disturbances, highlighting the distinct roles of prokaryotic and eukaryotic communities in coastal subtidal zones and providing valuable insights for the management and conservation of coastal subtidal marine ecosystems. Full article

Global oyster reefs have suffered severe degradation due to human activities, environmental pollution, and climate change. The construction of artificial reefs offers a promising strategy to enhance oyster recruitment and mitigate population decline. However, the factors influencing oyster recruitment in artificial frameworks remain largely unclear, and it is still challenging to evaluate the effectiveness of different restoration methods. In this study, a series of oyster reef restoration experiments were conducted in the Tianjin coastal zone to identify key factors affecting recruitment success. These factors included restoration methods (shell string, mesh bag, and mesh cage), seeding with juvenile oysters, oyster shell orientation, and cultch hanging height. Our results indicated that the mesh bag method achieved the highest oyster settlement density in the intertidal zone, while the shell string method supported the fastest growth rates of oysters in the subtidal zone. The lower hanging height of cultches in the artificial frames increased oyster settlement density; however, hanging the cultches too close to the sediment negatively impacted oyster growth rates. Additionally, seeding with juvenile oysters and orienting the rough side of the shell upward enhanced recruitment performance. Oyster settlement density was greater in the intertidal zone (Bagua Shoal) compared to the subtidal zone (Dashentang), while oysters in the subtidal zone exhibited faster growth rates. Using redundancy analysis, the influence of environmental factors on the oyster recruitment performance was assessed. Oyster growth in the subtidal zone was positively correlated with dissolved oxygen and pH, whereas oyster settlement density in the intertidal zone was positively associated with water temperature, chlorophyll a concentration, and salinity. Finally, we evaluated the effectiveness of different restoration methods by considering factors including reef construction costs, oyster settlement abundance, average daily shell growth rate, water purification potential, and reef subsidence. Our results demonstrated that the shell string method was the most effective in the Dashentang subtidal zone, while the mesh bag method with oyster seeding was optimal in the Bagua Shoal intertidal zone. Our findings can provide valuable insights and guidance for oyster reef restoration projects. Full article

Seagrass is a key primary producer in coastal ecosystems; however, most studies on seagrass-benthos interactions have focused on subtidal zones. Some species such as Zostera japonica grow in intertidal flats; however, their ecological functions remain unclear. Understanding whether intertidal seagrass beds contribute to benthic abundance and diversity can provide insights that facilitate tidal flat conservation. The present study clarifies the role of intertidal Z. japonica as a food source for benthos. Field surveys were conducted in an intertidal flat in Matsushima Bay, Japan. Five benthic species (Batillaria cumingii, Umbonium costatum, Phacosoma japonicum, Nereididae, and Paguroidea) were identified. Carbon and nitrogen stable isotope ratios (δ¹³C, δ¹⁵N) and fatty acid compositions of sediment organic matter, seawater, and target benthos were analyzed to determine food sources. The results showed that B. cumingii actively consumed Z. japonica-derived organic matter present in both seagrass and sandy sediments. Z. japonica also influenced bacterial community structure, providing a favorable habitat for Nereididae. Filter feeders (U. costatum and P. japonicum) exhibited minimal reliance on Z. japonica-derived organic matter. The findings suggest that, similar to subtidal seagrass ecosystems, intertidal seagrass meadows support benthic communities by supplying organic matter and enhancing bacterial production. Full article

Background: Jeju Island is a world-renowned tourist destination. However, with the increasing intensity of anthropogenic activities, the coastal marine environment of Jeju Island has been negatively affected. Methods and Results: Our study used five benthic indices to assess the ecological quality of the subtidal zone in northern Jeju Island. Our analysis indicated that apart from the benthic polychaetes amphipods index (BPA), other benthic indices assessed the ecological quality of the subtidal zone in northern Jeju Island as high or good. Distance-based redundancy analysis (dbRDA) indicated that pH and salinity primarily influenced macrobenthic communities in 2011 and 2012. According to the Spearman rank correlation analysis, the multivariate AZTI marine biotic Index (M-AMBI) showed stronger correlations with environmental data than other benthic indices. Conclusions: Overall, the averages of the five benthic indices suggested that the benthic ecological quality of the subtidal zone in the northern part of Jeju Island was high or good. Although immediate marine environmental management is not required, long-term monitoring remains essential. M-AMBI outperformed other benthic indices; however, we recommend using multiple benthic indices to assess the benthic ecological quality of Jeju Island due to the complexity of marine ecosystems. Effective support has been provided by our study for the marine environmental conservation along the coast of Jeju Island. Full article

Chitons are a group of mollusks (polyplacophores) that differ from the mollusks that are most often found on marine rocky shores (bivalves and gastropods). On the Atlantic coast of North America, chitons have been reported in subtidal habitats from Newfoundland (Canada) to New England (USA). Here, we report the finding of Boreochiton ruber at the mid-to-high intertidal zone in a wave-exposed habitat in Nova Scotia (Canada). After surveying various coastal locations across Nova Scotia for 20 years (2004 to 2024), this was the only intertidal chiton we ever found in such habitats, making this an extremely rare occurrence. Rare species may contribute in unique ways to community functioning, making their reports valuable for biodiversity and ecosystem research. Full article

The shale of different potential layers is studied by using rock pyrolysis analysis, total organic carbon determination (TOC), kerogen microscopic component identification, mineral X-ray diffraction, scanning electron microscopy, and low-temperature nitrogen adsorption experiments. The results are as follows: (1) Shishui Formation of the Lower Carboniferous and Longtan Formation of the Upper Permian are the two most important shale gas reservoirs in the Chenlei Depression. The sedimentary environment of the target shale is a marine land interaction facies coastal bay lagoon swamp sedimentary system. Two sedimentary facies of tidal flat facies, subtidal zone, and lagoon swamp facies are developed. (2) The organic matter types of shale are Type III and II₂, with TOC content greater than 1%. The maturity of shale samples is relatively higher (R_o,max is above 2%), which means they have entered the stage of large-scale gas generation. The overall brittle mineral content of the target shale sample is relatively higher (above 40%), which is conducive to artificial fracturing and fracture formation in the later stage, while an appropriate amount of clay minerals (generally stable at 40%) is conducive to gas adsorption. (3) The overall pore structure of the water measurement group and Longtan group is good, with a higher specific surface area and total pore volume (average specific surface area is 12.21 and 8.36 m²/g, respectively), which is conducive to the occurrence of shale gas and has good adsorption and storage potential. The gas content of the water measurement group and the Longtan Formation varies from 0.42 to 5 cm³/g, with an average of 2.1 cm³/g. It indicates that the water measurement group and the Longtan Formation shale gas in the study area have good resource potential. Full article

This study was conducted to assess the feasibility of biomass estimation by non-destructive sampling, determine whether the results derived from various types of marine macroalgae are reliable, and a newly proposed method. A quantitative survey was conducted on marine macroalgae communities distributed in the subtidal zone in 67 coastal regions in Korea. Regression analyses were conducted on 11,642 fresh weight datasets covering of 135 species of marine macroalgae. The linear function was FW = 17.721C (adj r² = 0.745, p < 0.001) and the power function was FW = 4.48C^1.251 (adj r² = 0.891, p < 0.001). Our analysis accounted for the fact that there were three vertically distributed layers of a marine macroalgal assemblages with various shapes (i.e., the Ecklonia complex, the Sargassum and Undaria complex, and the understory complex). For the Ecklonia complex, the linear function was FW = 27.360C (adj r² = 0.886, p < 0.001) and the power function was FW = 9.626C^1.223 (adj r² = 0.909, p < 0.001). For the Sargassum and Undaria complex, the linear function was FW = 18.389C (adj r² = 0.916, p < 0.001) and the power function was FW = 6.567C^1.255 (adj r² = 0.942, p < 0.001). For the understory complex, the linear function was FW = 10.419C (adj r² = 0.737, p < 0.001) and the power function was FW = 4.377C^1.182 (adj r² = 0.871, p < 0.001). Our findings demonstrated that the proposed method can accurately estimate the primary productivity of a wide range of coastal ecosystems based on remote sensing and non-destructive surveys of small-scale marine macroalgal communities. Full article

Beachrocks are a window to the past environmental, geological, sedimentological and morphological conditions that were dominant in the coastal zone during their formation. Furthermore, beachrocks have the ability to reduce coastal erosion impact on sandy beaches. This study focuses on the beachrock formation mechanism through the comparison of cement characteristics, mineral chemistry and sedimentology of beachrock occurrences from two different geological and geographical localities: Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. In addition, in order to investigate a potential soft engineering method to protect coasts from erosion, artificial beachrock samples were created in vitro using sand samples and ureolytic bacteria from both areas under accelerating conditions. For Okinawa artificial beachrock experiments, the bacteria Pararhodobacter sp. was used, and for Diolkos, it was the bacteria Micrococcus yunnainensis sp. For the natural beachrocks, a multi-analytical approach was accomplished with the use of microscopic investigation, a scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray fluorescence. Correlations were made between natural and artificial beachrocks. Results have shown that Diolkos beachrock was formed in the upper part of the intertidal zone, consisting of detrital material originating from the local bedrock, while Sumuide beachrock formed in the low intertidal–upper subtidal zone, consisting of coral sand and foraminifera fragments. For the artificial beachrocks, three samples were created using the microbial-induced carbonate precipitation (MICP) method, one from Diolkos (Corinth, Greece) and two from Sumuide (Okinawa, Japan). Diolkos artificial beachrock was better consolidated in comparison to Sumuide. Our investigation has shown that bacterial density was the key factor for the creation of the artificial beachrocks, while the samples’ granulometry played a secondary role in the process. The laboratory artificial beachrocks show encouraging results for a new soft engineering method to encounter beach erosion while keeping an ecofriendly character by saving energy, material resources and gas emissions. Artificial beachrocks can share the same properties of a natural beachrock and can contribute positively to marine biodiversity as a natural rocky habitat. Full article

This study aimed to investigate the dynamics of the nutrient budget of a macroalgal community exposed to water discharged from aquaculture farms. This study was conducted in the coastal area exposed to water discharged from aquaculture farms located on Jeju Island, Korea, in May and October of 2017. Water-column-dissolved inorganic nutrient concentrations were higher in the intertidal zone than in the subtidal zone. High nutrient concentrations in the intertidal zone resulted in the bloom of Ulva spp., consequently leading to a low species number. This indicates the vulnerability of the intertidal macroalgal community to discharge from land-based aquaculture. Ecklonia cava contributed to 29–53% of the total incorporation of carbon (C), nitrogen (N), and phosphorus (P) in the subtidal zone. In the intertidal zone, the highest tissue N content was found in Ulva spp. due to the high and rapid nutrient uptake rate from the effluent with high nutrient concentrations, thereby indicating high total N incorporation. The estimated total C, N, and P incorporation rates by macroalgae were 181.5, 8.6, and 0.95 tons year⁻¹, respectively. These results suggest that the macroalgal community in this area absorbs or removes large amounts of nutrients from the water column and plays an important role in the budgets and cycling of nutrients in the surrounding coastal areas. Full article

The temperate Northwest Pacific brown alga Rugulopteryx okamurae (Dictyotales, Phaeophyceae) was first discovered in 2002 in the Mediterranean Sea in the Thau coastal lagoon (Occitania, France) and then again in 2015 along the southern side of the Strait of Gibraltar, where it was assigned with invasive status. We report here on the first occurrence of the species in the Northwest Mediterranean Sea in Calanques National Park (Marseille, France) in 2018. By 2020, a large population had developed, extending over 9.5 km of coastline, including highly protected no-take zones. The seafood trade, with R. okamurae used as packing material for sea urchin Paracentrotus lividus shipments from Thau Lagoon, could be the vector of its introduction into the Marseille area. As observed in the Strait of Gibraltar, R. okamurae is spreading rapidly along the Marseille coasts, suggesting an invasive pathway. The subtidal reefs are densely carpeted with R. okamurae, which overgrows most native algal species. Fragments of the alga are continuously detached by wave actions and currents, sedimenting on the seabed and potentially clogging fishing nets, and thus, impacting artisanal fishing or washing up on the beaches, where they rot and raise concern among local populations. Full article

Research on physical ecosystem engineering—i.e., the structural modification of environments by organisms—has flourished during the last two decades. At present, the importance of physical ecosystem engineers for the biodiversity and the functioning of ecosystems is well recognized by scientists. This Special Issue contains fifteen papers that illustrate the diversity of physical ecosystem engineering processes that occur in the world coastal habitats—from coastal dunes to the shallow subtidal zone. It includes 2 reviews comparing ecosystem engineering attributes and impacts across taxa and 13 case studies that inform our general understanding of the variation in engineering impacts, compound engineering effects, novel engineering interactions, and engineered structural legacies. Full article

Submerged marine forests of macroalgae known as kelp are one of the key structures for coastal ecosystems worldwide. These communities are responding to climate driven habitat changes and are therefore appropriate indicators of ecosystem status and health. Hyperspectral remote sensing provides a tool for a spatial kelp habitat mapping. The difficulty in optical kelp mapping is the retrieval of a significant kelp signal through the water column. Detecting submerged kelp habitats is challenging, in particular in turbid coastal waters. We developed a fully automated simple feature detection processor to detect the presence of kelp in submerged habitats. We compared the performance of this new approach to a common maximum likelihood classification using hyperspectral AisaEAGLE data from the subtidal zones of Helgoland, Germany. The classification results of 13 flight stripes were validated with transect diving mappings. The feature detection showed a higher accuracy till a depth of 6 m (overall accuracy = 80.18%) than the accuracy of a maximum likelihood classification (overall accuracy = 57.66%). The feature detection processor turned out as a time-effective approach to assess and monitor submerged kelp at the limit of water visibility depth. Full article