Molecular analysis of green-tide-forming macroalgae in the Yellow Sea

In the summer of 2008, free-floating green algae bloomed in the Yellow Sea. Samples were collected in a wide area (119°32′-122°00′E, 32°25′-36°49′N). We calculated the sequence divergences of nuclear ITS, chloroplast rbcL, and psbA data of free-floating samples collected from the Yellow Sea and Ulvaceae from Europe and Japan. In the ITS sequence, 19 out of the 21 Yellow Sea samples of 2008 were identical to those of a sample taken at Qingdao in 2007. A low divergence (0.2%) was found in remaining two samples. Similar evidence was shown by pairwise distances of rbcL and psbA gene sequence data, implying the uniformity of the Yellow Sea blooms in 2007 and 2008. The ITS sequence of the Yellow Sea samples differed 8.1-10.8% from free-floating Enteromorpha or Ulva reported worldwide. ITS-based molecular phylogenetic results and rbcL sequence data grouped the free-floating alga in the Yellow Sea into one clade with Enteromorpha procera, Enteromorpha linza and Enteromorpha prolifera. Furthermore, both morphological characteristics and ribotype network of the ITS sequences imply that the blooming algae in 2007 and 2008 were E. prolifera. The haplotypes of the Yellow Sea free-floating E. prolifera are closely related to those from the Japanese coast but less to European and American algae.     

管壳缝类硅藻中国新记录属种——非洲南氏藻

利用光学和电子显微镜对采自黄海水域的1个管壳缝类硅藻——非洲南氏藻进行了形态学研究,并对其地理分布进行了讨论.结果表明:(1)该种壳体带面呈矩形,壳面窄椭圆形,具有钝圆的末端.(2)壳缝居中,由两条等长的分支组成.(3)管壳缝由复杂、接合的肋突支撑,但无龙骨.(4)每条线纹仅有1个孔纹,壳套上最多有1列孔纹.(5)目前...     

Genetic variation of <Emphasis Type="Italic">Ulva (Enteromorpha) prolifera</Emphasis> (Ulvales,Chlorophyta)—the causative species of the green tides in the Yellow Sea,China

Ulva (Enteromorpha) prolifera, widely distributed from the intertidal to the upper subtidal zones around the world, was the dominant species of the massive green tides in the Yellow Sea in the summers of 2007, 2008, and 2009. However, little is known about its intra-species genetic diversity. In this study, six attached and seven floating U. prolifera samples collected from different sites distributed from the north of the Yellow Sea to the south of the East China Sea were taken in inter-simple sequence repeat (ISSR) analysis. Based on the results of the 90 polymorphic bands from four ISSR primers, the genetic diversity level of the floating samples (H = 0.1663, I = 0.2608) was found to be lower than that of the attached samples (H = 0.2105, I = 0.3346). Unweighted pair-group mean analysis (UPGMA) and principal coordinate analysis (PCoA) suggested that floating U. prolifera samples in the Yellow Sea from 2007 to 2009 had a close genetic relationship, and the floating samples were separated from the attached samples. Genetic differentiation and limited gene flow among attached U. prolifera populations were indicated by analysis of molecular variance.     

<Emphasis Type="Italic">Halobacillus locisalis</Emphasis> sp. nov., a halophilic bacterium isolated from a marine solar saltern of the Yellow Sea in Korea

A Gram-positive, motile, endospore-forming and rod-shaped halophilic bacterial strain MSS-155 (KCTC 3788 and KCCM 41687) was isolated from a marine solar saltern of the Yellow Sea in Korea and was subjected to a polyphasic taxonomic study. This organism grew at temperature of 10.0–42.0°C with an optimum of 35°C. Strain MSS-155 grew optimally in the presence of 10% NaCl and did not grow in the absence of NaCl. The cell wall peptidoglycan type of strain MSS-155 was A4 based on l-Orn-d-Asp. Strain MSS-155 was also characterized chemotaxonomically by having menaquinone-7 (MK-7) as the predominant isoprenoid quinone and anteiso-C_15:0 as the major fatty acid. The DNA G+C content was 44.0 mol%. Phylogenetic analysis based on 16S rDNA sequences showed that strain MSS-155 falls within the radiation of the cluster comprising Halobacillus species. Levels of 16S rDNA sequence similarity between strain MSS-155 and the type strains of four Halobacillus species were in the range 97.6–98.8%. Strain MSS-155 exhibited levels of DNA-DNA relatedness of 6.2–11.2% to the type strains of Halobacillus species described previously. On the basis of phenotypic properties, phylogeny, and genomic data, strain MSS-155 should be placed in the genus Halobacillus as a member of a novel species, for which we propose the name Halobacillus locisalis sp. nov.Communicated by W.D. Grant     

Effect of temperature on the growth,total lipid content and fatty acid composition of recently isolated tropical microalgae Isochrysis sp., Nitzschia closterium,Nitzschia paleacea,and commercial species Isochrysis sp. (clone T.ISO)

The effect of temperature from 10 °C to 35 °C on the growth, total lipid content, and fatty acid composition of three species of tropical marine microalgae, Isochrysis sp., Nitzschia closterium, N. paleacea (formerly frustulum), and the Tahitian Isochrysis sp. (T.ISO), was investigated.Cultures of N. closterium, Isochrysis sp. and T.ISO grew very slowly at 35 °C, while N. closterium did not grow at temperatures higher than 30 °C or lower than 20 °C. N. paleacea was low-temperature tolerant, with cells growing slowly at 10 °C. N. paleacea produced the highest percentage of lipids at 10 °C, while the other species produced maximum amounts of lipid at 20 °C. None of the species maintained high levels of polyunsaturated fatty acids (PUFAs) at high growth temperature and there was a significant inverse relationship between the percentage of PUFAs and temperature for N. paleacea. A curved relationship was found between temperature and percentage of PUFA for N. closterium and tropical Isochrysis sp., with the maximum production of PUFA at 25 °C and 20 °C, respectively. The two Nitzschia species produced higher levels of the essential fatty acid eicosapentaenoic acid [20:5(n-3)] at lower growth temperatures, but the two Isochrysis species had little change in percentage of 20:5(n-3) with temperature. Only T.ISO had the highest percentage of 22:6(n-3) at lowest growth temperature (11.4% total fatty acids at 10 °C).School of Mathematical and Physical SciencesAuthor for correspondence     

Growth rates of North Sea macroalgae in relation to temperature,irradiance and photoperiod

Three eulittoral algae(Ulva lactuca, Porphyra umbilicalis, Chondrus crispus) and one sublittoral alga(Laminaria saccharina) from Helgoland (North Sea) were cultivated in a flow-through system at different temperatures, irradiances and daylengths. In regard to temperature there was a broad optimum at 10–15° C, except inP. umbilicalis, which grew fastest at 10 °C. A growth peak at this temperature was also found in four of 17 other North Sea macroalgae, for which the growth/temperature response was studied, whereas 13 of these species exhibited a growth optimum at 15 °C, or a broad optimum at 10–15 °C. Growth was light-saturated inU. lactuca, L. saccharina andC. crispus at photon flux densities above 70 µE m^–2s^–1, but inP. umbilicalis above 30 µE m^–2s^–1. Growth rate did not decrease notably in the eulittoral species after one week in relatively strong light (250 µE m^–2s^–1), but by about 50 % in the case of the sublittoralL. saccharina, as compared with growth under weak light conditions (30 µE m^–2s^–1). In contrast, chlorophyll content decreased in the sublittoral as well as in the eulittoral species, and the greatest change in pigment content occurred in the range 30–70 µE m^–2s^–1. Growth rate increased continuously up to photoperiods of 24 h light per day inL. saccharina andC. crispus, whereas daylength saturation occurred at photoperiods of more than 16 h light per day inU. lactuca andP. umbilicalis.     

Thermoregulation and heterothermy in some of the smaller flying foxes (Megachiroptera) of New Guinea

Summary Body temperature, heterothermy, oxygen consumption, heart rate, and evaporative water loss were studied in four species of flying foxes (Megachiroptera), Dobsonia minor, Nyctimene major, Nyctimene albiventer, and Paranyctimene raptor, from the vicinity of Madang on the north coast of New Guinea.The thermoregulatory response of D. minor resembled that of most other placental mammals weighing 80 to 100 g. Body temperatures were relatively stable at ambient temperatures between 5 and 34°. The mean oxygen consumption at rest between 30 and 35° was 1.26 cc O₂ (g·hr)^–1. At ambient temperatures between 5 and 35° evaporative water loss averaged 4.5 mg (g·hr)^–1 and increased sharply at higher temperatures. When subjected to heat stress the animals panted, salivated, and licked the wings, belly, and uropatagium. At temperatures above 38° the ratio of heat lost through evaporation to heat production exceeded 1. Minimal heart rates in resting animals near thermal neutrality were approximately 275/min.In those parameters measured, N. major which weighed about 80 g resembled D. minor. Nyctimene albiventer and P. raptor weigh less than 30 g and are among the smallest of the flying foxes. Each shows both homeothermic and heterothermic patterns of response. At an ambient temperature of 35° the minimal oxygen consumption of homeothermic N. albiventer and P. raptor were 1.43 and 1.38 cc O₂ (g·hr)^–1, respectively. Oxygen consumption of homeothermic N. albiventer at 25°, 2.59 cc O₂ (g.hr)^–1, was almost quadruple that of torpid animals at the same temperature. During the daytime both N. albiventer and P. raptor characteristically allowed their body temperatures to fall to near 25°. Both readily aroused from the hypothermic state through physiological means. Heart rates of homeothermic N. albiventer resting at 35° ranged from 312 to 326/min while those of animals torpid at 25° were 88 to 96/min.The capacity for heterothermy has not previously been demonstrated in any members of the Megachiroptera, but our data indicate that it can occur on a daily basis in N. albiventer and P. raptor. This capacity appears to be related to size since it occurs in none of the larger flying foxes so far studied.The data presently available indicate that the relation of body weight to standard metabolism in the Megachiroptera is similar to that of the other placental mammals. In the species we studied, thermal conductances were higher, and heart rates, lower than predicted for mammals of their sizes.These studies were carried out during the 1969 Alpha Helix Expedition to New Guinea and were supported in part by grants GB-5139, GB-3656, and GB-8445 from the U. S. National Science Foundation.     

New cold-adapted lipase from Photobacterium lipolyticum sp. nov. that is closely related to filamentous fungal lipases

A Photobacterium strain, M37, showing lipolytic activity, was previously isolated from an intertidal flat of the Yellow Sea in Korea and identified as Photobacterium lipolyticum sp. nov. In the present study, the corresponding gene was cloned using the shotgun method. The amino acid sequence deduced from the nucleotide sequence (1,023 bp) corresponded to a protein of 340 amino acid residues with a molecular weight of 38,026. No sequence similarity was found with any known bacterial lipases/esterases; instead, the most similar enzymes were several filamentous fungal lipases. Although the similarity was very low (less than 16%), there were many conserved regions over the entire sequence and N-terminal oxyanion hole (RG) region, a signature sequence of filamentous fungal lipases. The novel protein M37 was produced in both a soluble and insoluble form when the Escherichia coli cells harboring the gene were cultured at 18°C. The soluble protein exhibited lipase activity in a pH-stat assay using an olive oil emulsion. The M37 lipase also displayed a maximum activity at 25°C and maintained its activity at a low temperature range (5–25°C) with an activation energy (E _a) of 2.07 kcal/mol. Accordingly, these results indicate that the M37 lipase from P. lipolyticum sp. nov. is a new cold-adapted enzyme.     

First Records of Dinoflagellates Alexandrium margalefi Balech, 1994 and A. tamutum Montresor, Beran et John, 2004 in the Seas of the Russian Far East

New records of two Alexandrium species are reported for the Russian seas. A. margalefi Balech was found in Peter the Great Bay (Sea of Japan), and A. tamutum Montresor, Beran et John was found in Aniva and Sakhalinskii bays (Sea of Okhotsk). Both species were observed in summer in small numbers at water temperatures of 22– 24°C and 8.6–11°C, respectively. Data on the morphology and distribution of the species is provided.Original Russian Text Copyright © 2005 by Biologiya Morya, Selina, Morozova.     

Temperature adaptation and the contractile properties of live muscle fibres from teleost fish

Summary The contractile properties of swimming muscles have been investigated in marine teleosts from Antarctic (Trematomus lepidorhinus, Pseudochaenichthys georgianus), temperate (Pollachius virens, Limanda limanda, Agonis cataphractus, Callionymus lyra), and tropical (Abudefduf abdominalis, Thalassoma duperreyi) latitudes. Small bundles of fast twitch fibres were isolated from anterior myotomes and/or the pectoral fin adductor profundis muscle (m. add. p). Live fibre preparations were viable for several days at in vivo temperatures, but became progressively inexcitable at higher or lower temperatures. The stimulation frequency required to produce fused isometric tetani increased from 50 Hz in Antarctic species at 0°C to around 400 Hz in tropical species at 25°C. Maximum isometric tension (P_o) was produced at the normal body temperature (NBT) of each species (Antarctic, 0–2°C; North Sea and Atlantic, 8–10°C; Indo-West Pacific, 23–25°C). P₀ values at physiological temperatures (200–300 kN·m^–2) were similar for Antarctic, temperate, and tropical species. A temperature induced tension hysteresis was observed in muscle fibres from some species. Exposure to <0°C in Antarctic and <2°C in temperate fish resulted in the temporary depression of tension over the whole experimental range, an effect reversed by incubation at higher temperatures. At normal body temperatures the half-times for activation and relaxation of twitch and tetanic tension increased in the order Antarctic>temperate>tropical species. Relaxation was generally much slower at temperatures <10°C in fibres from tropical than temperate fish. Q₁₀ values for these parameters at NBTs were 1.3 2.1 for tropical species, 1.7–2.6 for temperate species, and 1.6–3.5 for Antarctic species. The forcevelocity (P-V) relationship was studied in selected species using iso-velocity releases and the data below 0.8 P₀ iteratively fitted to Hill's equation. The P-V relation at NBT was found to be significantly less curved in Antarctic than temperate species. The unloaded contraction velocity (V_max) of fibres was positively correlated with NBT increasing from about 1 muscle fibre length·s^–;1 in an Antarctic fish (Trematomus lepidorhinus) at 1°C to around 16 muscle fibre lengths·s^–1 in a tropical species (Thalassoma duperreyi) at 24°C. It is concluded that although muscle contraction in Antarctic fish shows adaptations for low temperature function, the degree of compensation achieved in shortening speed and twitch kinetics is relatively modest.Abbreviations ET environmental temperature - m. add. p major adductor profundis - m. add. s. major adductor superficialis - NBT normal body temperature - P ₀ maximum isometric tension - P-V force velocity - SR sarcoplasmic reticulum - T 1/2 a half activation time - T 1/2 r half relaxation time - V _max unloaded contraction     

Effects of temperature and irradiance on photosynthesis and growth of a green-tide-forming species (<Emphasis Type="Italic">Ulva linza</Emphasis>) in the Yellow Sea

Samples of the massive drifting green alga, Ulva linza, were collected from the coastal waters of the Yellow Sea, southwest of Korea, in early July 2009, and cultured under laboratory conditions. The effects of various temperature (10–30°C) and irradiance levels (0–1,000 μmol photons m⁻² s⁻¹) on photosynthesis, growth, and tissue nutrient content of U. linza were investigated in laboratory for both individuals of the late-stage vegetation (LSV) and the early-stage vegetation (ESV). After 1 h acclimation to various irradiance and temperature conditions, maximum gross photosynthetic rate of ESV was significantly higher than those of LSV. In the long-term (7-d) acclimation experiments to various irradiance and temperature levels, gross photosynthetic rates of ESV individuals were also significantly higher than those of LSV individuals. High photosynthetic rate of ESV individuals induced increase in mass of about 60% over the growth saturation irradiance (136 μmol photons m⁻² s⁻¹) and about 20% under low temperature conditions (10–15°C) during 7-d. The gross photosynthesis of LSV individuals was low when examined under temperature and irradiance conditions that were optimum for ESV growth. Consequently, free-floating U. linza exhibits cellular senescence beginning in early July in the Yellow Sea, and green tides formed by this species cannot be maintained beyond this time in the open sea. However, we expect that U. linza can proliferate quickly after settlement on new coastal habitats of the Yellow Sea because of the high tissue nitrogen utilization for photosynthesis in ESV, which is formed by germination of reproductive cells.     

Aerobic mitochondrial capacities in Antarctic and temperate eelpout (Zoarcidae) subjected to warm versus cold acclimation

Capacities and effects of cold or warm acclimation were investigated in two zoarcid species from the North Sea (Zoarces viviparus) and the Antarctic (Pachycara brachycephalum) by investigating temperature dependent mitochondrial respiration and activities of citrate synthase (CS) and NADP⁺ -dependent isocitrate dehydrogenase (IDH) in the liver. Antarctic eelpout were acclimated to 5°C and 0°C (controls) for at least 10 months, whereas boreal eelpout, Z. viviparus (North Sea) were acclimated to 5°C and to 10°C (controls). Liver sizes were found to be increased in both species in the cold, with a concomitant rise in liver mitochondrial protein content. As a result, total liver state III rates were elevated in both cold-versus and warm-exposed P. brachycephalum and Z. viviparus, with the highest rates in boreal eelpout acclimated to 5°C. CS and IDH activities in the total liver were similar in Z. viviparus acclimated to 5°C and 10°C, but decreased in those warm acclimated versus control P. brachycephalum. Enzyme capacities in the total liver were higher in eelpout from Antarctica than those from the North Sea. In conclusion, cold compensation of aerobic capacities in the liver seems to be linked to an increase in organ size with unchanged specific mitochondrial protein content. Despite its life in permanently cold climate, P. brachycephalum was able to reduce liver aerobic capacities in warm climate and thus, displayed a capacity for temperature acclimation.     

Cumaceans as Indicators of Atlantic Waters over the Continental Slope of the Arctic Ocean

The material on cumacean fauna of the continental slope of the Arctic Ocean (more than 80 samples) was collected during expeditions with the ships Persei in 1925, 1928, and 1936; Sadko in 1936; and Polarstern in 1990, 1993, and 1995. Examination of the samples (150–900 m depth) revealed 19 species of Cumacea in this region. Three Arcto-Atlantic bathyal species (Hemilamprops uniplicatus, Diastylis echinata, Campylaspis globosa) are markers of the places over the continental slope where Atlantic intermediate waters penetrate into the Arctic Ocean and reach to the bottom. These species are widespread in the North Atlantic (100 to 2882 m depth); on the continental slope of the Arctic Ocean, they occur in a narrow depth range (200 to 900 m) in areas where positive temperatures from 0.09 to 1.78°C and high salinity of 34.75 to 34.87 prevail. The locations of these species is delineated on maps as an interrupted belt extending from northeastern Greenland to the East Siberian Sea and further north up to 79°30 N and 148° E, which corresponds to the route of penetration of Atlantic intermediate waters into the Arctic Ocean.     

Phylogenetic analysis of culturable marine bacteria in sediments from South Korean Yellow Sea

Biogeochemical and microbiological characterization of marine sediments taken from the Yellow Sea of South Korea was carried out. One hundred and thirty six bacterial strains were isolated, characterized and phylogenetic relationship was evaluated. The gene sequences of 16S rDNA regions were examined to study the phylogenetic analysis of bacterial community in the marine sediments. Among 136 isolates, 5 bacterial isolates were identified as novel members, remaining 131 isolates were fall into 5 major linkages of bacterial phyla represented as follows: Firmicutes,, -@Proteobacteria, High G + C and Bacteroidetes. Bacterial community in sediments mainly dominated by Firmicute (58.77%) and followed by @-Proteobacteria (38.16%). @-Proteobacteria domain highly diverged and mainly consists of the genera Vibrio, Marinobacterium, Photobacterium, Pseudoalteromonas, Oceanisphaera, Halomonas, Alteromonas, Stenotrophomas and Pseudomonas. Total N and Organic matter content in Yellow Sea of South Korea were relatively high. The Total-N content in the sediments was varied from 177.31 to 1974.96 (mg/kg) and organic matter ranged from 0.82 to 4.23 (g/100 g⁻¹). The current research work provides clear explanation obtained for the phylogenetic affiliation of the culturable bacterial community in sediments of South Korean Yellow Sea and revealed the relationship with biogeochemical characteristics of the sediments.     

Copepoda from deep-sea hydrothermal vents and cold seeps

Recent explorations of hydrothermal vents in the eastern Pacific (Juan de Fuca spreading zone, Guaymas Basin in the Gulf of California, East Pacific Rise at 21° N and 13° N, and Galapagos Rift) and on the Mid-Atlantic Ridge have revealed many copepods, mostly siphonostomatoids with few poecilostomatoids. In these habitats in depths from 1 808 to 3 650 m water temperatures may reach nearly 15 ° C. Among more than 22 000 copepods from vents examined two new families, 11 new genera, and 32 new species were represented.In addition, two new copepods were found in 3 260 m at cold seeps at the base of the West Florida Escarpment in the Gulf of Mexico, an environment not thermally active, with water temperatures about 4.39 °C.Some of these copepods were associated with host invertebrates such as a Nuculana-like protobranch bivalve, a polychaete, and two species of shrimps. Others were obtained from washings of bivalves or vestimentiferans or by means of corers or slurp guns.     

Upwelling and eddies affect connectivity among local populations of the goldeye rockfish,Sebastes thompsoni (Pisces,Scorpaenoidei)

The goldeye rockfish, Sebastes thompsoni, commercial rockfish catch in the Northwest Pacific Ocean, may influence its population structure. To clarify the population genetic structure of Korean S. thompsoni and its degree of hybridization with the most close species, Sebastes joyneri, we analyzed a mitochondrial (mt) DNA control region and eleven polymorphic microsatellite (ms) loci. S. joyneri individuals were clearly distinguished from S. thompsoni by the mtDNA control region and ms loci results, with single interspecific hybridization between two species suggesting no impact on genetic structure of S. thompsoni. Analysis of mtDNA revealed no population structure within S. thompsoni, suggesting the survival of a single population in southern refugia during the glacial period. The ms loci results, in contrast, showed two genetically distinct clusters within S. thompsoni: One was predominant throughout Korean coasts (from the Yellow Sea, via the Korea Strait to the East Sea); the other was predominant at Dokdo Island in the East Sea; and both occurred in similar ratios at Wangdolcho Reef in the East Sea. A possible factor that restricts gene flow between Korean coastal and offshore populations in the East Sea may be related to the complex oceanic current patterns such as eddies and upwelling, which represent impermeable barriers to population connectivity for this species. Our findings highlight that these two populations might be representative of two separate stock within Korean waters and maintain their geographically related genetic structure.     

The problem of invaders in the Caspian Sea in the context of the findings of new zoo- and phytoplankton species from the Black Sea

In April 2004, an expedition to the Caspian Sea discovered the species in the Middle Caspian not previously described in this sea. These species preliminary identified as Oithona similis Claus 1963, Sagitta setosa Muller 1847, and Calanus euxinus (Hulsemann) are the main representatives of edible plankton of the Black Sea; most likely they were introduced into the Caspian Sea with ballast waters of ships passing through the Volga-Don Canal. At present, it is difficult to say if these species will be established in the Caspian Sea; if so, they will clearly become a valuable food resource for planktophagous fish in the Caspian Sea. In addition, we discovered two diatom species typical for the Black Sea phytoplankton, Pseudo-nitzschia seriata (Cleve) H. Peragallo and M. Peragallo and Cerataulina pelagica (Cleve) Hendey which invaded the Caspian Sea in recent years. Pseudo-nitzschia seriata synthesizes a toxin (domoic acid) and can become harmful for the basin in the case of mass bloom. We discuss the problem of spontaneous invasion of alien species from the Black Sea and their effect on the Caspian ecosystem in the context of these findings.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 78–87.Original Russian Text Copyright © 2005 by Shiganova, Musaeva, Pautova, Bulgakova.     

Mytilid mussels: global habitat engineers in coastal sediments

Dense beds of mussels of the family Mytilidae occur worldwide on soft-bottoms in cold and warm temperate coastal waters and have usually been considered hot spots of biodiversity. We examined intertidal mussel beds at four distant locations around the globe with the same sampling method, to find out whether this “hot spot” designation holds universally. We studied species assemblages within the matrices of byssally interconnected mussels engineered by Mytilus edulis in the North Sea, by mixed Perumytilus purpuratus and Mytilus chilensis at the southern Chilean coast, by Musculista senhousia in the Yellow Sea and by Xenostrobus inconstans at the coast of southern Australia. In all cases, species assemblages inside mussel beds were significantly different from those outside with many species being restricted to one habitat type. However, species richness and diversity were not generally higher in mussel beds than in ambient sediments without mussels. In the North Sea (M. edulis) and at the Chilean coast (P. purpuratus, M. chilensis), mussel beds have markedly higher species numbers and diversities than surrounding sediments, but this was not the case for mussel beds in Australia (X. inconstans) and the Yellow Sea (M. senhousia) where numbers of associated species were only slightly higher and somewhat lower than in adjacent sediments, respectively. In conclusion, although soft bottom mytilid mussels generally enhance habitat heterogeneity and species diversity at the ecosystem level, mussel beds themselves are not universal centres of biodiversity, but the effects on associated species are site specific.     

Spatial, seasonal and species variations of harmful algal blooms in the South Yellow Sea and East China Sea

The occurrences of harmful algal blooms (HABs), in terms of frequency and area in the Chinese coastal waters, have been increasing since 1980s and caused considerable economic losses. In the present study, we have analyzed spatial and seasonal characteristics of HAB events in the southern Yellow Sea and East China Sea along Chinese coast from 1933 to 2004. With a total 435 HAB records, the most frequent HAB occurrence area (FHA) is off the Yangtze River mouth and another two FHA areas are located south of the Yangtze River estuary along about isobaths of 30–60 m coastal water in the East China Sea. The time of HAB occurrence shifted during our study period: from autumn (August–October) before 1980s to July–August in 1980s, during May–July in 1990s, and May–June for the period of 2000–2004. Causative species were found to be different: Noctiluca scintillans and Skeletonema costatum were dominant causative species prior to 2000; and Prorocentrum donghaiense Lu was dominant from 2000 to 2004 and also caused large blooms in May. Trichodesmium sp. caused many HABs in autumn (August–October) prior to 1980s with only one HAB between 1980 and 2004. The changes of the dominant HAB species may have affected the timings of HAB occurrence, as well as the increasing HAB-affected areas in recent years.