Search Results (12)

Human harvesting exerts significant pressure on intertidal ecosystems, yet its impact on community structure remains insufficiently understood. To assess these effects, we investigated macrobenthic communities on Lvhua Island and adjacent islets by integrating ecological surveys, questionnaire data, and Remote Sensing Ecological Indices (RSEI). We analyzed species composition, biomass, density, and diversity indices across seven sampling sites. Results showed distinct spatial variation: the eastern Lvhua Island exhibited higher biomass and density than the west, with the remote Manduishan islet highest and the South of West Lvhua near the pier the lowest. Harvesting hotspots were dominated by Chlorostoma rusticum and Cantharus cecillei, while less-disturbed islets were characterized by Chl. rusticum, Thais luteostoma, and Turbinidae. Economically valuable gastropods showed signs of miniaturization under intensive harvesting. Biodiversity indices correlated with RSEI, and ABC curve analysis indicated moderate disturbance overall, with the greatest impact at the Donglvhua Bridge site. These findings indicate that a daily subsistence harvest of 100–150 kg resulted in a 31.82% decline in the Shannon-Wiener index, altering the community structure. RSEI provides a cost-effective complement to field monitoring and should be integrated into management frameworks to support both ecological conservation and community livelihoods. Full article

This paper aims to explore the impact of marine ranching construction on water quality and fishery resources in the surrounding marine areas. Utilizing in situ water quality and fishery resource data collected before and after the establishment of marine ranching, the study analyzes changes in water quality parameters from both temporal and spatial perspectives. A quantitative evaluation of the water quality data is conducted using several models to assess the accuracy of different evaluation methods. By integrating the SHAP algorithm with physical significance, the study examines the differences between optically sensitive and non-optically sensitive water quality parameters during the machine learning evaluation process. Finally, based on the inverted water quality data, the potential impact range and resource output following the deployment of artificial reefs are investigated. The results indicate that in the marine area near Wailingding Island, Zhuhai, the deployment of artificial reefs with a volume of 38,048 cubic meters led to an increase in fishery resources by 318 kg/km² in spring and 660 kg/km² in autumn. Additionally, deployment had varying degrees of impact on the concentrations of chlorophyll a (Chla), dissolved oxygen (DO), chemical oxygen demand (COD), and phosphate (PO4-P) in the surface water within an approximate range of 10 km. This study provides a valuable reference for calculating input–output ratios, as well as for the management and evaluation of marine ranching. Full article

Wheat growth is highly sensitive to temperature fluctuations, and with the intensification of global climate change, low-temperature stress has become more frequent during various growth stages of wheat, severely affecting its growth and reducing wheat yield. An experiment examined the effects of low-temperature (daytime 8:00–20:00/nighttime 20:00–next day 8:00: 16 °C/8 °C, 12 °C/4 °C, 8 °C/0 °C, and 4 °C/−4 °C) and exposure durations (1, 3, and 5 days) on winter wheat yield during the anthesis stage. Compared to exposure duration, temperature was the main factor affecting dry matter accumulation, distribution, and transport. Temperature had an average influence of 79.7%, 57.5%, 61.9%, and 79.0% on dry matter distribution in the stem-sheath, leaf, spike axis+glume, and grain, respectively. It also affected pre-anthesis translocation amount, the contribution of pre-anthesis translocation to grains, post-anthesis accumulation amount, and the contribution of post-anthesis accumulation to grains by 48.3%, 55.1%, 44.2%, and 48.2%, respectively. Conversely, exposure duration mainly influenced grain-filling parameters, with an average effect of 43.8%, 44.0%, 83.3%, and 43.8% on the maximum filling rate, average filling rate, filling rate in the fast-increasing period, and filling rate during the slow growth period, respectively. Low-temperature duration also significantly altered the fast-increasing period, slow growth period, and grain weight per spike by 79.9%, 79.9%, and 51.3%, respectively. Low-temperature stress alters the accumulation and distribution of dry matter in wheat, and the duration of exposure further affects the grain-filling process, ultimately resulting in a decrease in yield. Full article

Seaweed farming has made outstanding contributions to food supply and the restoration of the ecological environment despite the limitations in production and ecological effects due to the current intensive farming of single algae species. These limitations can be overcome by selecting suitable algal species based on their physiological characteristics and by constructing a large-scale seaweed rotation model. This study carried out a trial culture in aquaculture sea areas, and performed in situ monitoring of the environmental conditions and physiological characteristics of Saccharina japonica, Hizikia fusiformis, and Gracilariopsis lemaneiformis. Additionally, a comparative analysis of the three macroalgae at different times was conducted to determine their response characteristics to environmental factors. The results showed that: (1) The three macroalgae had varying light tolerance. The effective quantum yield of Hizikia fusiformis and Gracilariopsis lemaneiformis remained unchanged during the changes in light environment, while that of Saccharina japonica first decreased and then recovered. (2) The relative electron transport rates of the three macroalgae were significantly different under different temperature conditions. Hizikia fusiformis and Saccharina japonica exhibited the highest relative electron transport rates (70.45 and 106.75, respectively) in May (20.3 °C). Notably, Gracilariopsis lemaneiformis demonstrated good growth and exhibited the highest relative electron transport rate (93.07) in September (27.5 °C). These findings collectively support the feasibility of establishing a macroalgae rotation model. Based on the combined environmental conditions of the seas in Shandong, Zhejiang, and Fujian, a macroalgae rotation model was proposed. The application of this model in the construction of artificial seaweed farms in marine ranches can provide a stable output of large-scale seaweed production and ecological benefits. Full article

The aim of this study was to use unmanned aerial vehicles (UAVs) as a supplement to satellite remote sensing to accurately assess benthic seaweed biomass in intertidal zones, in order to improve inversion accuracy results and investigate the spatial distribution patterns of seaweed. By adopting non-multicollinearity vegetation indices (feature sets) from PlanetScope and Sentinel-2, and using benthic seaweed biomass inverted from multispectral UAV imagery as the label set for satellite pixel biomass values, machine learning methods (Gradient boosting decision tree, GBDT) can effectively improve the accuracy of biomass estimation results for Ulva pertusa and Sargassum thunbergii species (Ulva pertusa, $R_{Sentinel2}^2$ = 0.74, $R_{PlanetScope}^2$ = 0.8; Sargassum thunbergii, $R_{Sentinel2}^2$ = 0.88, $R_{PlanetScope}^2$ = 0.69). The average biomasses of Ulva pertusa and Sargassum thunbergii in the intertidal zone of Gouqi Island are 456.84 g/m² and 2606.60 g/m², respectively, and the total resources are 3.5 × 10⁸ g and 1.4 × 10⁹ g, respectively. In addition, based on the hyperspectral data, it was revealed that a major source of error is the patchy distribution of seaweed. Full article

Seaweed communities perform a variety of ecological services, including primary productivity supply, biological habitat construction, water purification, and acting as marine carbon sinks. The abundance of seaweed is the basis for the assessment of ecological services in communities. The Ma’an Archipelago, adjacent to the Yangtze River estuary in China, is an important and typical island group. In this study, the abundance of seaweed in the typical coastal islands of the Ma’an Archipelago, Zhejiang Province, was evaluated by means of sonar detection and scuba diving sampling methods. The organic carbon content of six dominant seaweed species was measured to estimate the carbon sequestration capacity of the dominant species in the Ma’an Archipelago. The results show that 27 species of Rhodophyta, 10 species of Ochrophyta, and two species of Chlorophyta were found in the Ma’an Archipelago. Seaweed was distributed in the coastal areas of the islands, with a distribution width of 2–60 m. Gouqi Island had the longest shoreline, and there, the distribution depth of the seaweed reached 15 m and the area of the seaweed community was the largest. The slope of the rocks in the Sanheng survey area was large and the width of the seaweed community was small. The distribution area of seaweed in the Ma’an Archipelago was 6.51–13.43 km² and the organic carbon content of the seaweed was 33.16 ± 3.26%. The biomass of Ochrophyta in the Ma’an Archipelago was the largest, followed by Chlorophyta and Rhodophyta. Among the six dominant species, the carbon sequestration of Sargassum thunbergii was the largest, at 277.91–848.74 t per year, and that of Undaria pinnatifida was the smallest. This study provides scientific guidance for the assessment of the primary productivity supply, carbon sink, and conservation capacity of seaweeds in China. Full article

Objective: To detect the chemical constituents in Jianqu samples under different fermentated states by using UPLC-QTOF-MS/MS technology, to conduct preliminary analyses, and to establish an HPLC method for the simultaneous determination of hesperidin and naringenin in Jianqu, and the variation of the two components during fermentation were compared. Methods: Waters ACQUITYTM UPLC HSST3 column (2.1 mm × 100 mm, 1.8 μm) was used; the mobile phase was 0.1% formic acid aqueous solution (A)-0.1% formic acid acetonitrile (B); The flow rate was 0.4 mL·min⁻¹ with gradient elution; the column temperature was 45 °C; injection volume was 5 μL. The mass spectra of the samples were collected by negative ion mode under the electrospray ion source, and the data were screened and matched by UNIFI software. Hypersil gold C18 column (100 mm × 2.1 mm, 1.9 μm) was used; the mobile phase was acetonitrile (A)-0.1% acetic acid (B);; the flow rate with gradient elution was 0.3 mL·min⁻¹; the column temperature was 30 °C; the injection volume was 2 μL. The content changes of hesperetin and naringenin in Jianqu at different fermentation time were detected. Results: A total of 54 compounds were identified, including flavonoids, amino acids, organic acids, terpenoids, coumarins, lignans, and other compounds. Under the selected HPLC conditions, the linear relationship between hesperidin and naringenin was discovered (r² = 0.9996). The content of hesperidin and naringenin changed significantly in the whole fermentation process. The highest concentration of content was observed at 36 h of fermentation and then decreased to varying degrees. Conclusion: This experiment can effectively identify various chemical components in Jianqu during different fermentation periods, and determine the content of the characteristic components, so as to provide a scientific basis for further study of Jianqu fermentation processing technology as well as a sound pharmacodynamic material basis. Full article

This study aimed to investigate the practical validity of the environmental DNA (eDNA) method for evaluating fish composition and diversity in different habitats. We evaluated the fish composition and diversity characteristics of seven different habitats in the Ma’an Archipelago Special Protected Area in April 2020. The results showed that a total of twenty-seven species of fishes belonging to six orders, eighteen families, and twenty-three genera of the Actinopterygii were detected in the marine waters of the Ma’an Archipelago Special Protected Area. The dominant species in each habitat were Larimichthys crocea, Paralichthys olivaceus, and Lateolabrax maculatus. The mussel culture area had the highest number of species, with 19 fish species, while the offshore bulk load shedding platform had the lowest number of species, with 12 fish species. The rest of the habitat was not significantly different. The results showed that the mussel culture area had the highest diversity index (average value of 2.352 ± 0.161), and the offshore bulk load shedding platform had the lowest diversity index (average value of 1.865 ± 0.127); the rest of the habitat diversity indices did not differ significantly. A comparison with historical surveys showed that the eDNA technique can detect species not collected by traditional methods such as gillnets and trawls. Our study demonstrates the role of eDNA technology in obtaining fish diversity in different habitats and provides a theoretical basis for the continuous monitoring and management of fish biodiversity in protected areas. Full article

Probing the coverage and biomass of seaweed is necessary for achieving the sustainable utilization of nearshore seaweed resources. Remote sensing can realize dynamic monitoring on a large scale and the spectral characteristics of objects are the basis of remote sensing applications. In this paper, we measured the spectral data of six dominant seaweed species in different dry and wet conditions from the intertidal zone of Gouqi Island: Ulva pertusa, Sargassum thunbergii, Chondrus ocellatus, Chondria crassiaulis Harv., Grateloupia filicina C. Ag., and Sargassum fusifarme. The different seaweed spectra were identified and analyzed using a combination of one-way analysis of variance (ANOVA), support vector machines (SVM), and a fusion model comprising extreme gradient boosting (XGBoost) and SVM. In total, 14 common spectral variables were used as input variables, and the input variables were filtered by one-way ANOVA. The samples were divided into a training set (266 samples) and a test set (116 samples) at a ratio of 3:1 for input into the SVM and fusion model. The results showed that when the input variables were the normalized difference vegetation index (NDVI), ratio vegetation index (RVI), V_re, A_be, R_g, L_re, L_g, and L_r and the model parameters were g = 1.30 and c = 2.85, the maximum discrimination rate of the six different wet and dry states of seaweed was 74.99%, and the highest accuracy was 93.94% when distinguishing between the different seaweed phyla (g = 6.85 and c = 2.55). The classification of the fusion model also shows similar results: The overall accuracy is 73.98%, and the mean score of the different seaweed phyla is 97.211%. In this study, the spectral data of intertidal seaweed with different dry and wet states were classified to provide technical support for the monitoring of coastal zones via remote sensing and seaweed resource statistics. Full article

UAV remote sensing inversion is an efficient and accurate method for obtaining information on vegetation coverage, biomass and other parameters. It is widely used on forest, grassland and other terrestrial vegetation. However, it is rarely used on aquatic vegetation, especially in intertidal zones and other complex environments. Additionally, it is mainly used for inversion of coverage, and there have been few studies thus far on biomass assessment. In this paper, we applied multispectral UAV aerial photography data to evaluate the biomass of seaweed in an intertidal zone. During the ebb tide, UAV aerial photography and in situ sampling data were collected in the study area. After optimizing the spectral index and performing a multiple linearity test, the spectral parameters were selected as the input of the evaluation model. Combined with two machine learning algorithms, namely random forest (RF) and gradient boosting decision tree (GBDT), the biomasses of three species of seaweed (Ulva pertusa, Sargassum thunbergii and Sargassum fusiforme) in the intertidal zone were assessed. In addition, the input parameters of the machine learning algorithms were optimized by one-way ANOVA and Pearson’s correlation analysis. We propose a method to assess the biomass of intertidal seaweed based on multispectral UAV data combined with statistics and machine learning. The results show that the two machine learning algorithms have different accuracies in terms of biomass evaluation using multispectral images; the gradient boosting decision tree can evaluate the biomass of seaweed in the intertidal zone more accurately. Full article

Sargassum fusiforme is a seaweed species that plays an important role in the diverse communities of the flora and fauna of coastal food webs. Assessments of its biomass and energy allocation in addition to allometric organ growth have important ecological value for understanding the community structure, carbon storage, and resource assessment of seaweed beds during periods in which they thrive. In this study, the morphology of Sargassum fusiforme and the biomass of organs and total organisms in the maturation period were studied, and the allometric relationships for different organs of Sargassum fusiforme were analyzed using the standardized major axis (SMA). In the maturation period of Sargassum fusiforme, branch number, height × stem diameter were the prior independent variables, and the optimum biomass was y = 0.002x^1.107 (R² = 0.923). The biomass allocation ratio of blades was the highest (38.33%), followed by stems (32.90%) and receptacles (28.77%). The growth rates of the various organs were found to differ, and the rate of biomass increase for the blades and stems tended to converge. The rate of receptacle biomass growth of Sargassum fusiforme was the highest in the maturation period, and the rate of organ biomass increase was W_b < W_s < W_t < W_r, which reflects the trade-off with energy allocation as a strategy used by Sargassum fusiforme. Full article

Sargassum vachellianum and Sargassum horneri are the main dominant species and primary producers of seaweed beds in Chinese coastal ecosystems that play an important role in marine blue carbon sinks. However, due to the influence of frequent human activities and global climate change, the seaweed beds formed by Sargassum vachellianum and Sargassum horneri in Chinese coastal waters are gradually declining. In this study, Sargassum zygotes were cultured onto the surface of mussels and then used to repair the declining seaweed bed resources through seaweed transplantation, which was indirectly achieved based on the fast attachment of mussel byssus. The results show that zygotes of Sargassum vachellianum and Sargassum horneri could grow on the surface of mussels and, over time, the force and rate of mussel adhesion gradually increased. The adhesion of Mytilus coruscus was greater than that of Septifer virgatus mussels. After four hours, the rate of adhesion for Mytilus coruscus with a shell length of 30 mm was 100%, and the adhesion force was the highest, at 0.511 ± 0.099 N. Hence, Mytilus coruscus showed better adhesion than Septifer virgatus. After 41 days, the mean length of Sargassum horneri germlings on the surface of Mytilus coruscus grew to 5.554 ± 0.724 mm, the daily growth rate was about 0.154 mm/d, and the mean density declined by 50.59%. After 31 days, the mean length of Sargassum vachellianum germlings increased to 5.510 ± 0.763 mm, the daily growth rate was about 0.191 mm/d, and the mean density declined by 21.21%. After 2 months of development of the mussel–seaweed combinations in coastal waters, the survival rate of Sargassum horneri was 7.6 ± 0.9% and that of Sargassum vachellianum was 25.9 ± 10.5%. Hence, compared with Sargassum horneri, Sargassum vachellianum attached to Mytilus coruscus showed better development, and this system can be used to combat the decline in seaweed bed resources. In this method, mussels were used as an intermediate attachment medium to indirectly achieve the settlement of zygotes for seaweed transplantation, and, therefore, their use as a substratum serves as the basis for a novel technique for seaweed beds restoration. Full article