Investigation of the decline of Ulva prolifera in the Subei Shoal and Qingdao based on physiological changes

It has been a scientific consensus that Ulva prolifera green tide that break out annually between May and August in the recent decade off eastern coast of Yellow Sea. To investigate the ecological mechanism of the decline of U. prolifera green tide, we compared the physiological characteristics of U. prolifera samples collected in three stages of the green tide in Subei Shoal north Jiangsu, the initiation point, on May 10(early, the initiation), July 10(middle, the outbreak), and in Taipingjiao, Qingdao on August 10(late, the decline). Compared to the early samples, the middle, and late samples showed a lower chlorophyll content and photosynthetic e fficiency at a higher lipid peroxidation level. The middle and later samples had fewer chloroplasts in the cells of U. prolifera than those in the early samples. In addition, the cells of U. prolifera sampled in the late stage showed ruptured and deformed cell walls. Differences in physiological function were reflected in the growth rate. Both the middle and late U. prolifera samples presented negative growth rates. Correlation analysis results show that the rising temperature was mainly responsible for the local decline of U. prolifera green tide. The high light-intensity that could induce the photoinhibition was also an important factor for the decline. Therefore, U. prolifera population that remained in the Subei Shoal and those that northward drifted to Qingdao experienced the same decline processes: rising temperature and continuous high light conditions in the late phase of green tide reduced the photosynthetic capacity and destroyed the antioxidant system of the thallus, which lead to decrease of biomass. The only difference is that the temperature in the Subei Shoal rose earlier than that in Qingdao; thus, U. prolifera remaining in the Subei Shoal went disappeared first.     

The distribution of green algal micro-propagules and macroalgae at the early stage of green tide in the coastal area of South Jiangsu Province in 2014

An integrated investigation was carried out during late April to late May of 2014 in the coastal area of South Jiangsu Province to understand the early development of green tide in the Yellow Sea and discover the temporal and spatial distribution of green algal micro-propagules and macroalgae at the early stage of green tide. The results showed that green algal micro-propagules distributed in all stations from late April to late May, and micro-propagules of high density( 300 ind. L~(-1)) concentrated in the adjacent Porphyra aquaculture area. Floating macroalgae were initially observed in the northern survey areas, and increased gradually. The dominant species was U. prolifera in the floating macroalgae, ranging between 90% and 100%. The seawater surface temperature and salinity in the above mentioned time period were suitable for the growth of macroalgae. This work can help government to strengthen management to reduce the blooms of macroalgae in the coastal area of South Jiangsu Province and also facilitate the decision-making for managers at the early stage of green tide.     

Ulva and Enteromorpha (Ulvaceae, Chlorophyta) from two sides of the Yellow Sea: analysis of nuclear rDNA ITS and plastid rbcL sequence data

Ulvacean green seaweeds are common worldwide; they formed massive green tides in the Yellow Sea in recent years, which caused marine ecological problems as well as a social issue. We investigated two major genera of the Ulvaceae, Ulva and Enteromorpha, and collected the plastid rbcL and nuclear ITS sequences of specimens of the genera in two sides of the Yellow Sea and analyzed them. Phylogenetic trees of rbcL data show the occurrence of five species of Enteromorpha (E. compressa, E. flexuosa, E. intestinalis, E. linza and E. prolifera) and three species of Ulva (U. pertusa, U. rigida and U. ohnoi). However, we found U. ohnoi, which is known as a subtropical to tropical species, at two sites on Jeju Island, Korea. Four ribotypes in partial sequences of 5.8S rDNA and ITS2 from E. compressa were also found. Ribotype network analysis revealed that the common ribotype, occurring in China, Korea and Europe, is connected with ribotypes from Europe and China/Japan. Although samples of the same species were collected from both sides of the Yellow Sea, intraspecific genetic polymorphism of each species was low among samples collected worldwide.     

Eranno carrerai sp. nov., a new polychaete worm (Lumbrineridae) from coastal waters of China

In this paper, a new polychaete species, Eranno carrerai sp. nov. from coastal areas of China, is described based on specimens deposited in the Marine Biological Museum of the Chinese Academy of Sciences, Qingdao, collected during 1957 to 1976 from the Yellow Sea, East China Sea and South China Sea at depths of 9–210 m.     

The Ulva prolifera genome reveals the mechanism of green tides

The genome of green microalgae has rarely been reported.Ulva prolifera is a green microalga that has received much attention.Despite research articles about U.prolifera in recent years,we know very little about its genome.Therefore,the 87.9-Mb haploid genome(containing 10 311 protein-coding genes)of U.prolifera was studied,and the genome was compared with that of U.mutabilis,which is the only published Ulva species.Results showed that the two species are closely related.A phylogenetic tree was constructed among U.prolifera and other green algae available in GenBank,revealing the evolutionary status of U.prolifera in Chlorophyta.To understand why U.prolifer a could grow rapidly,we identified some genes related to growth,such as those involved in cell division,phosphorylation,and cell proliferation.In addition,genes related to stress resistance were found,which supports the notion that U.prolifera grows vigorously in nature.These results help to characterize green tides from a new perspective and reveal some important insight into the biology of U.prolifera.     

Morphology and molecular identification of Ulva forming green tides in Qingdao, China

Green tides are caused by the proliferation of chlorophytes under suitable hydrographic conditions.These blooms lead to environmental degradation and negatively impact the waters and seagrass beds,as well as fishing and other recreational activities in the bay.A comprehensive ecological understanding of the bloom dynamics,including the origin and persistence,is needed to foster management decisions.The algae in the great majority of green tide blooms usually belong to two genera of Ulvophyceae,Ulva and Enteromorpha.Ulva has been observed more often in recent years.In China,green tides occurred for the first time in the middle area of the Yellow Sea in 2007,and a large-scale algae blooming broke out in the middle and southern areas of the Yellow Sea in late May 2008.We identified them as Ulva prolifera by comparative analysis of the rDNA internal transcribed spacer 1 (ITS1),5.8S and ITS2 sequences in combination with microscopic observation.Morphological differences were found between the free-floating algae and the attached thalli.Various reproduction patterns of the free-floating algae include sexual,asexual and vegetative propagations,which played important roles in the long-term green tide persistence in China.The ITS sequences of the blooming algae were identical to those of the samples from the Lianyungang sea area but were different from the attached samples from the Qingdao sea area.The results infer that the blooms are originated from other sea areas rather than from the local attached populations.     

Acute toxicity of live and decomposing green alga Ulva (Enteromorpha) prolifera to abalone Haliotis discus hannai

From 2007 to 2009, large-scale blooms of green algae (the so-called “green tides”) occurred every summer in the Yellow Sea, China. In June 2008, huge amounts of floating green algae accumulated along the coast of Qingdao and led to mass mortality of cultured abalone and sea cucumber. However, the mechanism for the mass mortality of cultured animals remains undetermined. This study examined the toxic effects of Ulva (Enteromorpha) prolifera, the causative species of green tides in the Yellow Sea during the last three years. The acute toxicity of fresh culture medium and decomposing algal effluent of U. prolifera to the cultured abalone Haliotis discus hannai were tested. It was found that both fresh culture medium and decomposing algal effluent had toxic effects to abalone, and decomposing algal effluent was more toxic than fresh culture medium. The acute toxicity of decomposing algal effluent could be attributed to the ammonia and sulfide presented in the effluent, as well as the hypoxia caused by the decomposition process.     

The possibility analysis of habitats, origin and reappearance of bloom green alga （Enteromorpha prolifera） on inshore of western Yellow Sea

Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008,authors analyze the necessary conditions and possible water area in China producing a large biomass,some reasons for firestorm,and the possibility of the reappearance of marine bloom green alga Enteromorpha prolifera.The change of habitats and the increase of nutritional levels related to the water area could be considered as direct reasons.It was ...     

A new species and new recorded species of Lumbrineridae Schmarda, 1861 (Annelida: Polychaeta) from China

Based on material deposited in the Marine Biological Museum of the Chinese Academy of Sciences(Qingdao),a new species,Lumbrineris sinensis sp.nov.,as well as Augeneria albidentata(Ehlers,1908),which is recorded for the first time from coastal water of China,are reported in the present paper.The specimens examined were collected during 1958 to 1960 from the Yellow Sea,East China Sea and South China Sea at depths of 4 to 182 m.     

DNA barcoding assessment of green macroalgae in coastal zone around Qingdao,China

An assessment with assistance of DNA barcoding was conducted on green macroalgae in coastal zone around Qingdao, China, during the period of April–December, 2011. Three markers were applied in molecular discrimination, including the plastid elongation factor tufA gene, the internal transcribed spacer (ITS) region of the ribosomal cistron and rubisco large subunit gene 3′ regions (rbcL-3P). DNA barcoding discriminated 8 species, excluding species of genus Cladophora and Bryopsis due to failures in amplification. We ascertained and corrected 4 species identified by morphological methods for effectively assisting the classification. The gene tufA presented more advantages as an appropriate DNA marker with the strongest amplification success rate and species discrimination power than the other two genes. The poorest sequencing success largely handicapped the application of ITS. Samples identified by tufA and rbcL as Ulva flexuosa were clustered into the clade of U. prolifera by ITS in the neighbor-joining tree. Confusion with discrimination of the complex of U. linza, U. procera and U. prolifera (as the LPP complex) still existed for the three DNA markers. Based on our results, rbcL is recommended as a preferred marker for assisting tufA to discriminate green macroalgae. In distinguishing green-tide-forming Ulva species, the free-floating sample collected from the green tide in 2011 was proved to be identical with U. prolifera in Yellow Sea for ITS and rbcL genes. This study presents a preliminary survey of green macroalgae distributed in the coastal area around Qingdao, and proves that DNA barcoding is a powerful tool for taxonomy of green macroalgae.     

Comparison of environmental responding strategies between Ulva prolifera and Sargassum horneri: an in-situ study during the co-occurrence of green tides and golden tides in the Yellow Sea,China in 2017

Journal of Oceanology and Limnology - Large-scale green tides in the Yellow Sea occurred for 13 consecutive years since 2007. The unusual co-occurrence of green tides and golden tides occurred in...     

Tidal current observation in the southern Yellow Sea in the summers of 2001 and 2003

Direct current observations in the Yellow Sea interior are very scarce due to intense fishing and trawling activities. Most previous studies on tides in the area were based on coastal measurements or satellite altimeter sea levels and have not been rigorously compared with direct measurements. In this paper, tidal currents are studied with current profiles from three bottom-moored Sontek Acoustic Doppler Profilers （ADPs） deployed in the southern Yellow Sea in summer of 2001 and 2003. The measured current series were dominated by tidal currents. Maximum velocities are between 40-80 cm/s at the mooring stations. M2 current is the most dominant primary tidal constituent, while MS4 and M4 are the most significant shallow water tides with much smaller amplitudes than the primary tides.     

Pyrolytic characteristics and kinetics of the marine green tide macroalgae, Enteromorpha prolifera

The marine macroalgae Enteromorpha prolifera was one of the main algal genera that occurred in the widespread green tides in Qingdao, China, during the summers of 2007, 2008 and 2010. It is thus a plentiful source of biomass and could be used as a biofuel. In this study, the pyrolytic characteristics and kinetics of E. prolifera were investigated using thermogravimetric analysis (TGA) method. Cornstalk and sawdust were used as comparisons. Pyrolytic characteristics were studied using TG-DTG (thermogravimetry-derivative thermogravimetry) curves. Three stages in the pyrolytic process were determined: dehydration, dramatic weight loss and slow weight loss. E. prolifera was pyrolyzed at a lower initial temperature than the two terrestrial biomass forms. The apparent activation energy values for the three types of biomass were calculated and the mechanism functions were determined using 16 different mechanism functions, frequently used in thermal kinetics analysis. Activation energy values varied with mechanism function and the range of activation energy values for E. prolifera, cornstalk, and sawdust were 25-50 kJ/mol, 60-90 kJ/mol and 120-155 kJ/mol, respectively. This indicates that E. prolifera has low thermal stability for pyrolysis and good combustion characteristics.     

Phylogenetic analyses of four species of Ulva and Monostroma grevillei using ITS, rbc L and 18S rDNA sequence data

Chlorophyta species are common in the southern and northern coastal areas of China. In recent years, frequent green tide incidents in Chinese coastal waters have raised concerns and attracted the attention of scientists. In this paper, we sequenced the 18S rDNA genes, the internal transcribed spacer (ITS) regions and the rbcL genes in seven organisms and obtained 536-566 bp long ITS sequences, 1 377-1 407 bp long rbcL sequences and 1 718-1 761 bp long partial 18S rDNA sequences. The GC base pair content was highest in the ITS regions and lowest in the rbcL genes. The sequencing results showed that the three Ulva prolifera (or U. pertusa) gene sequences from Qingdao and Nan’ao Island were identical. The ITS, 18S rDNA and rbcL genes in U. prolifera and U. pertusa from different sea areas in China were unchanged by geographic distance. U. flexuosa had the least evolutionary distance from U. californica in both the ITS regions (0.009) and the 18S rDNA (0.002). These data verified that Ulva and Enteromorpha are not separate genera.     

Karyological observations of Ulva linza chromosomes

Journal of Oceanology and Limnology - Ulva linza is one of the species that causes green tides in the Yellow Sea, China. Due to the difficulties in chromosomal preparation, the large numbers of...     

Antioxidant system responses in two co-occurring green-tide algae under stress conditions

Green tides have occurred every year from 2007 to 2014 in the Yellow Sea. Ulva prolifera(Müller) J. Agardh has been identified as the bloom-forming alga,co-occurring with U. intestinalis. We observed distinct strategies for both algal species during green tides. U. prolifera exhibited a high abundance initially and then decreased dramatically,while U. intestinalis persisted throughout. The antioxidant system responses of these two macroalgae were compared in the late phase of a green tide(in-situ) and after laboratory acclimation. Lipid peroxidation and antioxidant system responses differed significantly between the two. Malondialdehyde and hydrogen peroxide contents increased significantly in-situ in U. prolifera,but not in U. intestinalis. In U. prolifera,we observed a significant decrease in total antioxidant ability(T-AOC),antioxidant enzymes(SOD and Apx),and non-enzyme antioxidants(GSH and As A) in-situ. U. intestinalis showed the same pattern of T-AOC and SOD,but its Gpx,Apx,and GSH responses did not differ significantly. The results suggest that U. prolifera was more susceptible than U. intestinalis to the harsh environmental changes during the late phase of a Yellow Sea green tide. The boom and bust strategy exhibited by U. prolifera and the persistence of U. intestinalis can be explained by differences in enzyme activity and antioxidant systems.     

First report of the genus Lysippe Malmgren, 1866 (Polychaeta: Ampharetidae) from Chinese waters

The ampharetid genus Lysippe Malmgren, 1866 is reported for the first time from Chinese waters. The identification was based on material deposited in the Marine Biological Museum of the Chinese Academy of Sciences (Qingdao). A new species, Lysippe trichobranchia sp. nov. is described. The new species is widely distributed in shallow waters of the Bohai Gulf, the Yellow Sea and the East China Sea at depths of 10-40 m.     

Two new marine benthic diatom species of Hippodonta (Bacillariophyceae) from the coast of China: H. nanjiensis sp. nov. and H. qingdaoensis sp. nov.

The diversity and distribution of Hippodonta species on the coast of China are largely unknown due to limited investigations. In this paper, we report the detailed morphology and ultrastructure of two new species: H. nanjiensis sp. nov., collected from intertidal sandy sediments of Nanji Islands, the East China Sea and H. qingdaoensis sp. nov., collected from intertidal sandy sediments of the No. 1 Bathing Beach in Qingdao City, the Yellow Sea. Both species occur mainly in the middle part of the intertidal zone. H. nanjiensis possesses a unique large round central area. H. qingdaoensis differs from congeners in having a unique stria pattern, wherein the areolae in the middle transapical striae are less developed or absent on the primary side of the valve, and two areolae per stria are apparent under light microscopy(LM). This study expands our knowledge of Hippodonta diversity and distribution on the coast of China.     

Preliminary comparison of trace metals in coastal aerosols between Qingdao and Liverpool

Aerosol samples were collected at two coastal suburban stations, Qingdao （China） in 1995-1996 and Liverpool （U.K.） in 1995, respectively. The samples were analyzed to determine the concentrations of trace metals （Cr, Zn, Cu, Co, Ni, Pb, V, and Cd） as well as A1, Fe and Mn. Data were examined to understand the difference of trace metals in aerosols between coastal zones downwind the developing area （near the Yellow Sea） and developed region （near the Irish Sea）. The results show that most elements at Qingdao have levels 4-5 times higher than those at Liverpool, particularly for the crust-dominated elements （e.g. Al, Fe and Mn）. Moreover, the aerosol composition at Qingdao is higher in spring than in summer, underlying the influence of westerlies and local emissions in combination, whereas seasonal change of aerosol composition is not significant at Liverpool. The enrichment factors for the crustal source elements （EFcrust） at Liverpool are much higher than those at Qingdao. The contributions from the pollutant source （Rp） for some trace metals like Cu, Pb, Zn and Cd are 〉90% at Qingdao and Liverpool, suggesting overwhelming anthropogenic contributions to these metals. The contributions from crustal source （Re） for trace metals tend to increase with higher aerosol levels and Al concentration at Qingdao, indicating a good correlation between the crust-dominated component and the air mass. At Liverpool, the Rc values for trace metals are positively correlated with Al concentrations instead of with aerosol mass, suggesting that Al in aerosols represents the crustal component even though the aerosols come from different sources.     

Tempo-spatial distribution of Ulva spp. micro-propagules in the Yellow Sea during and after green tide in 2019

Journal of Oceanology and Limnology - Large-scale green tides occur frequently in summer in the Yellow Sea in recent decade. Micro-propagules, providing “seeds” for the seaweeds, play...