Southern Yellow Sea Research Articles

Predicting the sound speed of seafloor sediments in the Middle area of the Southern Yellow Sea based on a BP neural network model

Based on the data of the sound speed and the physical–mechanical properties of 300 seafloor sediment samples collected in the middle area of the Southern Yellow Sea, a backpropagation (BP) neural network algorithm is used herein to study the neural network topology and the corresponding neuron characteristic factors. A neural network model for predicting the sound speed of the seafloor sediment based on density, water content, porosity, void ratio, liquid limit, plastic limit, and clay content in the middle area of the Southern Yellow Sea is established. The results show that the sound speed prediction accuracy is the highest when the network model contains seven input layer neurons, ten hidden layer neurons, and one output node. According to the prediction results, the MAE(Mean Absolute Error) and the MAPE(Mean Absolute Percentage Error) are 13.19 m s−1 and 0.85%, respectively. The prediction results illustrate that the established BP neural network prediction method for the seafloor sediment sound speed is better than the traditional single, two and multi-parameter prediction equations.

Distribution of phytoplankton in the East China Sea and the southern Yellow Sea in spring in relation to environmental variables and dimethylsulfide compounds

Distribution of phytoplankton in the East China Sea and the southern Yellow Sea in spring in relation to environmental variables and dimethylsulfide compounds

Long-term nutrient variation trends and their potential impact on phytoplankton in the southern Yellow Sea, China

Long-term nutrient variation trends and their potential impact on phytoplankton in the southern Yellow Sea, China

Changes in Organic Carbon Delivery to the Yangtze River Delta Over the Last 2000 Years

Natural processes and anthropogenic activities are vital in dictating the amount and character of organic carbon (OC) input into large river deltas and adjacent shelves. Previous studies have indicated that sediment from the Huanghe River (HR) has significantly affected the formation of the northern Yangtze River subaqueous delta (YRD) over the past several hundred years. However, whether this process has changed sedimentary OC burial in the YRD remains unclear. A sediment core was collected from the YRD in 2018 CE for optically stimulated luminescence and 210Pb dating as well as grain size, total OC, total nitrogen, and stable-isotope analyses to investigate temporal changes in sedimentary OC over the past 2000 years. The results indicate that changes in terrestrial OC inputs to the YRD have been controlled mainly by the East Asian summer monsoon and anthropogenic influences in the past 2000 years. However, the decreased terrestrial OC inputs after 1385 CE, have been significantly affected by increased contribution of HR sediment to the YRD when the HR lower courses shifted to enter the southern Yellow Sea. This study demonstrates that sediment source changes should not be neglected in analyses of mechanisms and variations in OC burial in estuarine and coastal areas.

Application of Airborne LiDAR Measurements to the Topographic Survey of the Tidal Flats of the Northern Jiangsu Radial Sand Ridges in the Southern Yellow Sea

The northern Jiangsu radial sand ridges are typical geomorphic deposit units distributed off the Jiangsu coast. A coastal tidal flat typically develops and provides a good habitat for many migratory birds and benthic organisms. However, topographic surveys of tidal flats have always been difficult in marine surveys because of the dense tidal creek, poor accessibility, and difficulty in setting up control points. In this study, we quickly obtained the point cloud data of the tidal flat near Yangkou Port in the southern part of the radial sand ridges based on an airborne LiDAR system, an integrated 3D laser scanner and a positioning and attitude determination system. We analyzed the adaptabilities of multiple filtering algorithms to tidal flats. In addition, a digital elevation model (DEM) of the tidal flat was constructed and the accuracy was verified with synchronized beach GPS-RTK topographic elevation measurements. The results show that the following: (1) Airborne LiDAR can quickly obtain high precision, high resolution, and a large area of ground point cloud information for tidal flats, overcoming the shortcomings of traditional measurement methods. (2) The triangulated irregular network (TIN) filtering effect is better than that of mathematical morphology and the filtering effect of point cloud normal vector clustering is mediocre. (3) The DEM of the LiDAR point cloud is in good agreement with RTK and the average error of the measurement results is 0.108 m. The error accuracy of the DEM satisfies the surveying specification of a 1:500 topographic map in a flat area, which proves that the airborne LiDAR system can be suitable for tidal flat elevation measurement. Nevertheless, it is possible to provide high precision terrain detection and DEM construction of a tidal flat with the development of airborne infrared and blue-green laser detection radar.

Reproductive Dynamics of the Large Yellow Croaker Larimichthys crocea (Sciaenidae), A Commercially Important Fishery Species in China

The large yellow croaker Larimichthys crocea (Richardson, 1846) (Sciaenidae) is distributed in southern Yellow Sea, East China Sea, and northern South China Sea of China and is a commercially important nearshore fishery species. L. crocea was listed on the IUCN Red List as “Critically Endangered” in 2020 mainly due to the over-exploration of its spawning and over-wintering aggregations in the 1950s–1980s throughout its distribution region. However, detailed studies on reproductive dynamics of L. crocea were limited in the past three decades. In this study, the reproductive dynamics of L. crocea was examined in the traditional Guanjingyang (GJY) spawning ground, one of the 15 well-known ones in its distribution region. Samples were collected using set nets from April 2019 to November 2021 to ensure at least 20 samples for all 12 months. A total of 1,006 individuals were caught, ranging from 46 to 391 mm standard length (SL) and 1.45 to 1,110.05 g body weight (BW). A growth dimorphism was found between sexes with females heavier than males when body sizes exceeded 61 mm SL (non-parametric ANCOVA, p < 0.01). Gonad histology of all 1,006 individuals revealed, for the first time, that L. crocea was able to spawn almost year-round for both females and males. Two spawning peaks, spring and autumn, were identified in March and May and in November for females and in April to June and in October to November for males. The minimum sizes at sexual maturity were 160 mm SL for females and 112 mm SL for male. The sizes at 50% sexual maturity were 187.2 mm SL for females and 150.2 mm SL for males. Results showed that the minimum SL for female maturity decreased about 20% in the past six decades. The spawning peaks were 2 months earlier in spring and 1 month extension in autumn in GJY. Clearly, the national fishing moratorium regulation in May to August, an important fishery management measure in China, can only protect the spring spawning peak partly. Further evaluation on the influence of climate change on reproductive strategies and stock recruitment of L. crocea is highly recommended.

An evolving marine environment and its driving forces of algal blooms in the Southern Yellow Sea of China

Continuing global warming and intensification of human activities have substantially disturbed the balance of coastal marine ecosystems, potentially creating favorable conditions for algal blooms. Using serial remote sensing data and various national and provincial statistics, we investigated the spatial and temporal variations of the environmental driving forces for algal blooms in the Southern Yellow Sea between 2003 and 2017. The findings suggest that (1) Continual warming was observed in the Southern Yellow Sea. The study area evidenced more than three times the warming speed (0.41 °C/decade) of the global oceans (0.12 °C/decade) during the same period. There was an apparent warming zone in the region where macroalgal blooms tended to spread, with a heating of 1.0–1.5 °C (May–June). (2) Nutrient loadings have diverse patterns, characterized by fast-growing aquaculture activities and declining nutrients from land-based agriculture fertilizers and sewage discharge (based on published national and provincial statistics). (3) Growing expansion of algal blooms in the Southern Yellow Sea was confirmed by the relative increases in average May–June chlorophyll-a concentration of 46.7% and floating biomass area from 3.3% in 2003 to 13.4% in 2017. (4) While spatial correlation analysis showed a positive influence of the ocean surface temperature on chlorophyll-a, their relatively moderate (r = 0.40, p < 0.15) and declining correlations suggest that nutrient enrichment could be comparatively more influential on macroalgal blooms. Nutrient loading from the discharge of wastewater sourced from coastal aquaculture and organic residuals from land-sourcing sewage and industrial pollution, even though declining as reported, is still upholding a high level of nutrient enrichment in the study area. In addition, the fixed facilities for seaweed mariculture in the region provide vast breeding surfaces for algae. Consequently, the Southern Yellow Sea has become an ideal marine area for algal blooms.

First Report on Large-Scale Phaeocystis globosa Bloom in the Southern Yellow Sea, China

From late November 2021, a large-scale Phaeocystis globosa bloom occurred for the first time in the southern Yellow Sea, covering an area of over 630 km2 and lasting for nearly 40 days. Two investigations, combined with satellite remote sensing, were successively conducted on December 11 and 23, 2021 to study the bloom dynamics and impacts. During the bloom, the average temperature decreased from 11.8°C to 10.0°C and salinity increased slightly from 30.9 to 31.3. The pH remained consistently at 8.22, while dissolved oxygen and chlorophyll-a content decreased dramatically from 7.23 mg L-1 to 5.82 mg L-1, 8.72 μg L-1 to 2.35 μg L-1, respectively. The concentration of nitrate and silicate decreased moderately, whereas nitrite, ammonium and phosphate increased obviously, especially the ammonium content, elevated from 0.90 μmol L-1 to 1.39 μmol L-1 during two investigations. Meanwhile, the P. globosa colony densities varied between 10 colonies L-1 and 185 colonies L-1, with a mean of 70.0 colonies L-1 on Dec. 11, and decreased dramatically to an average of 1.46 colonies L-1 on Dec. 23. Similarly, single cells decreased from 3.6×106 cells L-1 to 1.05×106 cells L-1 accordingly. Moreover, diameter of the colonies varied from 0.5 cm to 2.0 cm, with an average diameter of 1.0 cm, and no colonies smaller than 0.5 cm was observed in the bloom. Correlation analysis indicated temperature and salinity related with the colony abundance positively (P&amp;lt;0.001) and negatively (P&amp;lt;0.05), respectively, and silicate and nitrite concentration showed significant positive effects on solitary cell density (P&amp;lt;0.05). No mortality of marine organisms was observed and the haemolytic activity of Phaeocystis samples was low, varying between 13.07 Hu L-1 and 19.22 Hu L-1. Based on phylogenetic analysis, this P. globosa strain may represent a possible different ecotype which prefers low temperature and is less or nontoxicity.

Impacts of trophic interactions on the prediction of spatio-temporal distribution of mid-trophic level fishes

Habitat models have gradually become important tools for assessing and predicting the spatio-temporal distribution of marine organisms. Species are closely associated with each other through biological processes such as predation, competition and mutualism. Neglecting the interaction between species might lead to biased prediction of species distributions, especially for the mid-trophic level species. In this study, the performance of three different kinds of habitat models, i.e., single species distribution model (Generalized linear regression, GLM), ensemble species distribution model (ESDM), and joint species distribution model (JSDM), were evaluated and compared to investigate how trophic interactions will impact the spatio-temporal distributions of mid-trophic fish species in the central and southern Yellow Sea. Potential variations in the distribution and abundance of five mid-trophic level fishes in the central and southern Yellow Sea under climate changes were also analyzed. Results showed that mutually associations derived from food web could explain a large proportion of the positive interactions among species. It was proved that JSDMs could reduce the bias in the estimation of abundance for mid-trophic level fishes by incorporating species trophic interactions, especially for species with low prevalence. The geographic center of gravity of five fishes showed a northward shift of less than 20 km under ocean warming scenarios. Ignoring species trophic interactions would result to overestimate or underestimate abundance of species under climate changes. The abundance of one species (Big head croaker Collichthys lucidus) would decrease, while the other four species would increase because of their different response to climate changes. This study is expected to improve our understanding of the importance of species interactions in predicting the spatio-temporal distribution of species, and will provide guidance for the spatial management strategies of fisheries resources under future climate changes.

Bacterial Community in Cold Surge-Caused Sea Ice Differs From Seawater in Mid-Latitude Region: A Case Study in Aoshan Bay, Southern Yellow Sea

Cold surges result in a rapid drop in air temperature and freezing of seawater, which was likely to impact bacterial communities. We examined the differences in bacteria abundance and bacterial community composition in the sea ice and seawater during a cold surge along Aoshan Bay, southern Yellow Sea in January 2021. Results showed that the differences in bacteria abundance between sea ice and seawater likely resulted from the physical impact of ice formation. The parent water played a key role in bacterial community composition in the early phase of ice formation, in which bacterial community compositions at class level were similar, but the relative abundances were different between sea ice and seawater. The Gammaproteobacteria dominated in sea ice, and the relative abundances of Verrucomicrobiae were also significantly higher, possibly due to the high concentration of algal-derived DOM in coastal areas. The predicted functional profiles suggested the lower abundance of functional genes related to ATP-binding cassette transporters in sea ice than in seawater, which might be due to the bacteria not requiring varieties of functional genes of ATP-binding cassette transporters in restricted sea ice brine.

The Formation of Coastal Turbidity Maximum by Tidal Pumping in Well‐Mixed Inner Shelves

AbstractCoastal turbidity maxima (CTMs) have been recognized on open coastal seas with elevated suspended sediment concentrations. Tidal pumping is often considered the major contributor to turbidity maxima in well‐mixed estuaries. However, its role in CTM formation on well‐mixed coasts remains unclear. Here, we propose a two‐dimensional depth‐averaged analytical model to explore residual sediment transport influenced by interactions between cross‐shore and along‐shore tidal currents. Observation data collected on the well‐mixed central Jiangsu coast (southern Yellow Sea), China, are analyzed by the model. The results display a persistent CTM close to the shore and show that the large along‐shore tidal velocity strongly influences the cross‐shore tidal pumping flux. The model calculation presents landward tidal pumping flux under horizontally homogeneous bed sediment distribution, illustrating the dominant role of tidal pumping in CTM formation within well‐mixed coastal water bodies. The model suggests that the significance of alongshore tidal current to cross‐shore sediment transport should be addressed in similar coastal environments.

Redefine Sustainable Fisheries Targets Under the Impact of the Southern Yellow Sea Green Tide: Mitigating the Recurring Surge in Natural Mortality

The massive green tide blooms caused by macroalgae Ulva in the Southern Yellow Sea, China, threaten the local fish populations. However, green tides are not factored into the determination of sustainable fisheries targets, which hinders the achievement of the maximum sustainable yield (MSY). Using a local fishery as a case study we highlighted the need to redefine the MSY-based targets in the face of green tides. We modeled the green tide blooms as natural mortality events and evaluated their effects on fisheries with the “green-tide-free” sustainable fishing intensity FMSY. We then recalculated these targets by accounting for the surges in natural mortality. We found that green tides caused at least 10% losses in biomass and catch when unaccounted for. Additionally, FMSY must be reduced by 4–8% to achieve MSY in the face of the green tide, which was approximately 20% lower than the “green-tide-free” value, indicating the damages of green tides could be partially mitigated.

Influences of the 1855 AD Huanghe (Yellow River) Relocation on Sedimentary Organic Carbon Burial in the Southern Yellow Sea

The Huanghe (Yellow River) supplies large amount of sediments and terrestrial organic carbon (OC) to the eastern Chinese marginal seas. A relocation of the Huanghe outlet from the southern Yellow Sea (YS) to the Bohai Sea occurred in 1855 AD, however, detailed knowledge about the impact of this relocation on sedimentary source and OC burial in Chinese marginal seas is still critically lacking. In this study, we present total OC content and its isotope (δ13C), along with bulk total organic carbon (TOC)/total nitrogen (TN) molar ratio and lipid biomarker contents, in a sediment core HH12 from the southern YS with sediment age spanning the last 300 years. We find that TOC and terrestrial lipid biomarker mass accumulation rates were lower between 1855 AD and 1950 AD than that prior to 1855 AD in core HH12; and in accordance, both TOC/TN ratio and δ13C records indicate a gradual decrease of terrigenous source contributions to sedimentary OC. This suggests that the relocation of the Huanghe outlet reduced the transport of terrestrial OC to the southern YS. However, the δ13C record also indicates a relative increase of terrestrial OC contribution to sedimentary OC after 1950 AD, and the most likely explanation is increased contributions from the old Huanghe delta erosion and Korean rivers. Future studies should focus on better constraining the variations of terrestrial and marine endmembers with δ13C and Δ14C analyses of specific biomarkers to examine these linkages.

Investigation on Natural Infection of Covert Mortality Nodavirus in Large Yellow Croaker, Larimichthys crocea

Covert mortality nodavirus (CMNV) recently became more prevalent, severely affecting farmed shrimps, and also other invertebrates and teleost fish, in the coastal areas of China. For better understanding of its prevalence and susceptibility of large yellow croaker Larimichthys crocea to CMNV, an epidemiological survey was carried out in the main producing areas (Ningbo, Zhejiang, China, and Ningde, Fujian, China) and its offshore feeding grounds in the Southern Yellow Sea. The collected cultured L. crocea individuals showed clinical symptoms such as anorexia and abnormal swimming and diagnosed for CMNV infection by using RT-nPCR assay. The positive rates for CMNV in the collected L. crocea samples from Ningbo, Ningde, and the Yellow Sea were 14.29% (4/28), 20.00% (7/35), and 16.67% (1/6), respectively. Furthermore, CMNV diagnosis using TaqMan probe-based reverse transcription quantitative PCR (TaqMan RT-qPCR) yielded positive rates of 25.00% (7/28), 22.86% (8/35), and 16.67% (1/6) respectively in the above-mentioned samples, and with a range of 12.73–3,108.33 of CMNV copy numbers/μg total RNA. Phylogenetic tree analysis based on the RNA-dependent RNA polymerase (RdRp) and capsid protein genes showed that CMNV isolates from L. crocea samples were clustered tightly with the original isolate of CMNV from Penaeus vannamei. The histopathological studies indicated that severe cellular necrosis occurred in the heart, liver, spleen, eye, and gill of naturally infected fish. Stronger positive signals for CMNV-specific probes appeared in the necrotic cells and tissues in the in situ hybridization (ISH) analysis. Transmission electron microscopy (TEM) revealed the presence of numerous 30 nm diameter CMNV-like viral particles. The purified CMNV suspension could cause a significant cytopathic effect (CPE) in epithelioma papilloma cyprini (EPC) cells and resulted in the formation of typical inclusion bodies, and also visible CMNV particles around the lysed EPC cells under the TEM. Taken together, all results of this study demonstrated that L. crocea is susceptible to CMNV. The prevalence of CMNV and its potential impacts on the wild population of L. crocea see the need for further investigations.

Functional diversity and groups of crustacean zooplankton in the southern Yellow Sea

Functional trait and functional diversity indices reflect the variations of community structure and indicate their responses to environmental stress. In this study, based on four functional traits, including body length, feeding type, trophic group, and reproductive mode, the functional diversity and functional groups of crustacean zooplankton from the southern Yellow Sea (SYS) were explored over four seasons of 2019. A total of 53 species were identified and categorized into six functional groups. Copepods with ambush-feeding and omnivore–carnivore diet (Group Ⅱ) were dominant in spring (55.6%), while omnivore–herbivore copepods (Group Ⅰ) were the most abundant group in the other three seasons (>54.7%). The comparable distributions of functional diversity indices in different seasons were most likely due to hydrological variations. The Changjiang River Diluted Water promoted the coexistence of multiple traits carried by different functional groups (high functional richness (FRic) and functional dispersion (FDis)), but the stability of ecosystem function in this water mass was vulnerable to the loss of individual species (low functional evenness (FEve)) in summer. In winter, as a result of the Yellow Sea Warm Current, warm-water taxa increased FRic and FEve, suggesting that the community could buffer environmental fluctuations more effectively. Moreover, distribution of FRic values indicates the possible range and influence intensity of the Yellow Sea Cold Water Mass.

Green Tides in the Yellow Sea Promoted the Proliferation of Pelagophyte Aureococcus anophagefferens.

Harmful algal blooms formed by fast-growing, ephemeral macroalgae have expanded worldwide, yet there is limited knowledge of their potential ecological consequences. Here, we select intense green tides formed by Ulva prolifera in the Yellow Sea, China, to examine the ecological consequences of these blooms. Using 28-isofucosterol in the surface sediment as a biomarker of green algae, we identified the settlement region of massive floating green algae in the area southeast of the Shandong Peninsula in the southern Yellow Sea. The responses of the phytoplankton assemblage from the deep chlorophyll-a maximum layer were then resolved using high-throughput sequencing. We found striking changes in the phytoplankton community in the settlement region after an intensive green tide in 2016, characterized by a remarkable increase in the abundance of the pelagophyte Aureococcus anophagefferens, the causative species of ecosystem disruptive brown tides. Our study strongly suggests that the occurrence of massive macroalgal blooms may promote blooms of specific groups of microalgae through alteration of the marine environment.

Research development on resource utilization of green tide algae from the Southern Yellow Sea

Since 2007, the Yellow Sea has undergone a large-scale outbreak of green tide for 15 years. The large biomass of green tide has caused great economic losses to Shandong and Jiangsu Province. The monitoring data in the recent years indicated that the dominant algae in the Southern Yellow Sea (SYS) was a special ecological type of Ulva species (Ulva prolifera). In order to make rational use of green tide algae and avoid the waste of biological resources, the achievements in the research and technical development on the resource utilization of green tide algae were systematically introduced. Moreover, the utilization and development of U. prolifera, such as food, beauty products, feed or feed additives, fertilizer, energy and papermaking engineering, were summarized. In addition, solutions to reduce the losses caused by the outbreak of green tide algae were also proposed.

Evaluation of Spawning- and Natal-Site Fidelity of Larimichthys polyactis in the Southern Yellow Sea Using Otolith Microchemistry

Small yellow croaker Larimichthys polyactis is an important commercial fish species; however, industrial-scale fishing has largely contributed to the changes in its biological characteristics, such as individual miniaturization, faster growth, and younger average age. Robust understanding of the pivotal life history of L. polyactis, a typical oceanodromous species, is needed for its conservation and restoration. However, L. polyactis fidelity to natal or spawning sites is not well understood and, at present, there is no effective management strategy to guarantee the sustainable exploitation of L. polyactis. This study used laser ablation inductively coupled plasma-mass spectrometry to analyse the elemental composition of otoliths from 60 adult yellow croakers caught in the southern Yellow Sea, including two spawning groups with 1- and 2-year-old fish (S1 and S2, respectively) sampled close to China and one overwintering group including two-year-old fish (O2) sampled close to South Korea. The ratios of elements (Li, Na, Sr, and Ba) to Ca in the otolith core zones were significantly higher (P &amp;lt; 0.05) than in those of the year one (Y1) and year two (Y2) annual rings, but there were no significant differences in the elemental ratios between the Y1 and Y2 zones. Principal component analysis (PCA) of the elemental otolith signatures of the core, Y1, and Y2 zones in the three groups revealed two distinct clusters (cluster 1: S1-core, S2-core, and O2-core zones; cluster 2: S2–Y1, O2–Y1, S2–Y2, and O2–Y2 zones) and one zone (S1–Y1), suggesting spawning-site fidelity and natal-site fidelity uncertainty, especially considering the dispersal by current in prolonged period (50 h) from fertilized eggs to hatching and internal effect, such as yolk sac and maternal effect. Furthermore, these results indicated that the S2 and O2 groups could represent the same population, suggesting a stable migratory route for L. polyactis in Chinese and South Korean waters, whereas the S1 group could represent another population. This suggests the possibility a mixed L. polyactis population in the southern Yellow Sea. Characterization L. polyactis spawning-site fidelity is a crucial step toward linking spawning-site fidelity of this overexploited species with thorough conservation and management strategies.

The Sandwich Structure of the Southern Yellow Sea Cold Water Mass and Yellow Sea Warm Current

The southern Yellow Sea Cold Water Mass (YSCWM) and the Yellow Sea Warm Current (YSWC) are prominent features in the southern Yellow Sea. The traditional viewpoint is that the southern YSCWM exists in the warm half of the year and the YSWC exists in the cold half of the year; the most existing studies have regarded these features as independent ocean phenomenon. Through marine investigations conducted in the recent years in the southern Yellow Sea, the southern YSCWM was found to exist in the early winter in 2010, and the YSWC was observed in the early summer in 2013, 2014. For approximately half the year, the southern YSCWM and YSWC existed simultaneously, and the YSWC was located in a slightly high-temperature region in the middle of the southern YSCWM. A sandwich-shaped temperature structure formed in the middle of the southern Yellow Sea from spring to autumn. This article studies the seasonal variation characteristics of the three-dimensional southern YSCWM and YSWC structures using ocean survey data collected in the recent years. The new perspective of the seasonal variations in the southern YSCWM and YSWC obtained herein will promote the recognition of southern Yellow Sea water exchanges and support biogeochemical cycle research in the Yellow Sea.

Physiological functional traits explain morphological variation of Ulva prolifera during the drifting of green tides.

Ulva prolifera green tides, one of the greatest marine ecological disasters, originate in the southern Yellow Sea of China and obtain the highest biomass in Haizhou Bay (latitude around 35° N) during northward drift. U. prolifera shows different morphologies from southern Haizhou Bay (SH) to northern Haizhou Bay (NH). Owing to the distinct nutrient environments between SH and NH, we hypothesized that thalli in NH with poor nutrients increased the surface area to volume ratio (SA:VOL) to better absorb nutrients. Here, we tested this hypothesis by comparing the SA:VOL of thalli in SH and NH. The results showed that the thalli in NH had a lower SA:VOL than those in SH, and SA:VOL had positive relationships with temperature and nutrients, contrary to the general hypothesis. The novel results suggested that morphological differences of U. prolifera were the result of developmental state rather than environmental acclimation. Indicators of reproduction (reproductive allocation ratio) were negatively related to variation in tissue contents of C, N, P, and crude protein, whereas indicators of growth (tissue contents of C, N, P, and crude protein) showed significant positive influences on SA:VOL. The results indicated that a trade‐off relationship between reproduction and growth existed in the northward drift. All the results suggested that physiological functional traits affected morphological variation of U. prolifera in different environmental conditions during the drifting of green tides. This study presents new insights into the opportunist species nature of U. prolifera through morphological variation and associated functional consequences.