The dominant Ulva strain of the 2008 green algal bloom in the Yellow Sea was not detected in the coastal waters of Qingdao in the following winter

The region of Qingdao, China, experienced the world's largest green tide from May to July 2008. More than one million tons of fresh algal biomass of the green alga Ulva prolifera was harvested, while more was suspected to have sunk to the bottom. The original source of this seaweed was suspected to be from the south as revealed by satellite images. The floating biomass drifted with the water current northward and flourished in nearshore waters around Qingdao. However, direct biological evidence for "seed" source is lacking. It is still unclear whether this alga could survive the Qingdao local coastal environment and pose future danger of potential blooming. Systematic and seasonal sampling of waters in the intertidal zone at six collection sites along the Qingdao coast was conducted from December 2008 to April 2009. Forty-eight water samples were analyzed. From these, nine different morphotypes of Ulva were grown in the laboratory under standard temperature and light regimes. Growth of Ulva was observed in all water samples. However, molecular phylogenetic analyses revealed that the dominant U. prolifera strain of the 2008 bloom was absent in all the water-derived cultures during the sampling period. These results provide evidence that the dominant bloom-forming alga was unlikely able to survive the coastal waters (the minimal surface water temperature in February is 2A degrees C) in winter conditions in Qingdao, even though all the sampling locations were heavily covered by this alga in June 2008.

Diversity and spatial distribution of sediment ammonia-oxidizing crenarchaeota in response to estuarine and environmental gradients in the Changjiang Estuary and East China Sea

Ammonia-oxidizing archaea (AOA) have recently been found to be potentially important in nitrogen cycling in a variety of environments, such as terrestrial soils, wastewater treatment reactors, marine waters and sediments, and especially in estuaries, where high input of anthropogenic nitrogen is often experienced. The sedimentary AOA diversity, community structure and spatial distribution in the Changjiang Estuary and the adjacent East China Sea were studied. Multivariate statistical analysis indicated that the archaeal amoA genotype communities could be clustered according to sampling transects, and the station located in an estuarine mixing zone harboured a distinct AOA community. The distribution of AOA communities correlated significantly with the gradients of surface-water salinity and sediment sorting coefficient. The spatial distribution of putative soil-related AOA in certain sampling stations indicated a strong impact of the Changjiang freshwater discharge on the marine benthic microbial ecosystem. Besides freshwater, nutrients, organic matter and suspended particles, the Changjiang Diluted Water might also contribute to the transport of terrestrial archaea into the seawater and sediments along its flow path.

Benthic foraminifera and bottom water evolution in the middle-southern Okinawa Trough during the last 18 ka

A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed based on the quantitative census data of benthic foraminiferal fauna, together with planktonic foraminiferal oxygen and carbon isotope, AMS(14)C dating, and the previous results achieved in the southern Okinawa Trough. The result shows that the benthic fauna was dominated by Bulimina aculeata (d'Orbigny), Uvigerina peregrina (Cushman), Hispid Uvigerina and Uvigerina dirupta (Todd) during the glaciation-deglaciation before 9.2 cal. ka BP, while Epistominella exigua (Brady), Pullenia bulloides (d'Orbigny), Cibicidoides hyalina (Hofker), Sphaeroidina bulloides (d'Orbigny) and Globocassidulina subglobosa (Brady) predominated the fauna in the post-glacial period after 9.2 cal. ka BP. The benthic foraminifera accumulation rate (BFAR), paleoproductivity estimates and benthic foraminiferal assemblage conformably indicate that surface water paleoproductivity and organic matter flux during the glaciation-deglaciation were higher than those of the post-glacial period in the middle-southern Okinawa Trough, and gradually enhanced from the southern to the central Okinawa Trough during the glaciation-deglaciation, which could be caused by the discrepancy of the terrigenous nutrients supply. High abundances of E exigua, an indicator of pulsed organic matter input, after 9.2 cal. ka. BP may indicate that the intensity of seasonally riverine pulsed flux during the post-glacial period was stronger than that of the glaciation-deglaciation period, and the seasonal influx in the central trough might be stronger than in the south. The temporal distributions of the typical species indicating bottom water oxygen content and ventilation condition show that the ventilation of the bottom water during the post-glacial period is more active than the glaciation-deglaciation, which reflects that the evolution of the intermediate and deep waters of the northwestern Pacific during the last glaciation has no evident influence on the deep-water of the middle-southern Okinawa Trough. Additionally, the variations in agglutinated benthic foraminiferal abundance and other carbonate dissolution proxies indicate that carbonate dissolution gradually increased since the last 18 ka in the Okinawa Trough and rapidly enhanced at 9.2 cal. ka BP. The modern shallow carbonate lysocline could form at 3 cal. ka BP.

Benthic foraminiferal distribution in surface sediments along continental slope of the southern Okinawa Trough: dependance on water masses and food supply

Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modem shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata, Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispida, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4), lower continental slope - trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua and Cibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottom agglutinated assemblage, dominated by Rhabdammina spp., Bathysiphon flavidus, corresponds to I strongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southern Okinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygen concentration and carbonate dissolution of the water masses are important controlling factors especially for the continental shelf break and trough bottom assemblages. The food supply also plays an important role in these benthic foraminiferal assemblages along the western slope. of the Okinawa Trough. Both the abundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supply along the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulate organic carbon) from the shelf break to the deep water is also an important food supply for benthic fauna in this region.

Isolation and identification of bacteria associated with the surfaces of several algal species

We conducted this study to assess the diversity of bacteria associated with the surfaces of algae based on 16S rDNA sequence analyses. Twelve strains of bacteria were obtained from the surfaces of the following four species of algae: Gracilaria textorii, Ulva pertusa, Laminaria japonica, and Polysiphonia urceolata. The isolated strains of bacteria can be divided into two groups: Halomonas and Vibrio, in physiology, biochemical characteristics and 16S rDNA sequence analyses. The phylogenetic tree constructed based on 16S rDNA sequences of the isolates shows four obvious clusters, Halomonas venusta, Vibrio tasmaniensis, Vibrio lentus, and Vibrio splendidus. Isolates from the surface of P. urceolata are more abundant and diverse, of which strains P9 and P28 have a 16S rDNA sequence very similar (97.5%-99.8%) to that of V. splendidus. On the contrary, the isolates from the surfaces of G textorii, U. pertusa and L. japonica are quite simple and distribute on different branches of the phylogenetic tree. In overall, the results of this study indicate that the genetic relationships among the isolates are quite close and display a certain level of host species specificity, and alga-associated bacteria species are algal species specific.

A preliminary study on the mechanism of harmful algal bloom mitigation by use of sophorolipid treatment

in order to investigate a new method of mitigating the deleterious effect of harmful algal blooms (HABs), the inhibition of the glycolipid biosurfactant sophorolipid on three common harmful algae Alexandrium tamarense, Heterosigma akashiwo and Cochlodinium polykrikoides was studied. The optimum preparation condition for sophorolipid, the inhibition capability of sophorolipid and the interaction mechanism of sophorolipid on the three algal species were investigated. Results showed that sophorolipid prepared by extraction with ethyl acetate exhibited the most prominent inhibition effect and that storage time of one year had little influence on the inhibition effect of sophorolipid. The optimum concentration of 10-20 mg/l sophorolipid inhibited the motility of about 90% of the tested harmful algal cells without recovery. Investigation of the algicidal process revealed that sophorolipid induced ecdysis of A. tamarense, quick lysis of H. akashiwo and swelling of C. polykrikoides in a relatively short time. Investigation of the nucleotides showed that more than 15% of the nucleotides were released from the cytoplasm under the effect of 10-20 mg/l sophorolipid, indicating the irreversible damage on the cellular membrane, which resulted in the disintegration of the harmful algal cells. (C) 2004 Elsevier B.V. All rights reserved.

Screening of surfactants for harmful algal blooms mitigation

Screening experiments were conducted in order to find promising synthetic surfactants for harmful algal blooms (HABs) mitigation. The chemically synthesized surfactant cocamidopropyl betaine (CAPB) showed characteristics of relatively high inhibition efficiency, high biodegradability and low cost. The motility inhibition ratios of 10 mg/L CAPB on Cochlodinium polykrikoides and Alexandrium tamarense were about 60% after 5 min. The biodegradation test indicated that the half-life of CAPB in seawater was shorter than one day and 90% was biodegraded after five days under the initial concentration of 100 mg/L at 25degreesC. Further cell lysis experiments revealed the selective lysis effect of CAPB on different HAB organisms. More than 90% of C. polykrikoides lysed at the concentration of 10 mg/L CAPB after 24 h and at 15 mg/L CAPB after 4 h, whereas the lysis effect of CAPB on A. tamarense was slight, no more than 10% after 2 h interaction with 50 mg/L CAPB. This research provided preliminary data for CAPB as a candidate in harmful algal blooms mitigation and pointed out unresolved problems for its practical application in the meantime. (C) 2003 Elsevier Ltd. All rights reserved.

Synergistic effect of sophorolipid and loess combination in harmful algal blooms mitigation

The inhibition effect of sophorolipid and removal efficiency of loess on Cochlodinium polykrikoides and Alexandrium tamarense was investigated separately in the laboratory. Based on this, the combination of sophorolipid and loess for harmful algal bloom mitigation was proposed. Algal sedimentation tests in the laboratory and in the field revealed that the combination of sophorolipid and loess showed synergistic effects both on the removal efficiencies and on the mitigation cost. The concentration of 1 g/l loess and 5 mg/l sophorolipid was determined as the optimum ratio for C polykrikoides mitigation. In the field test, the effective concentration of loess and sophorolipid in the combination group was reduced to 10% and 25%, respectively, compared to the non-combination group, and the cost decreased more than 60%. The combination of loess and sophorolipid was considered as a promising novel method in harmful algal bloom mitigation. (C) 2003 Elsevier Ltd. All rights reserved.

Environmental and health effects associated with Harmful Algal Bloom and marine algal toxins in China

The frequency and scale of Harmful Algal Bloom (HAB) and marine algal toxin incidents have been increasing and spreading in the past two decades, causing damages to the marine environment and threatening human life through contaminated seafood. To better understand the effect of HAB and marine algal toxins on marine environment and human health in China, this paper overviews HAB occurrence and marine algal toxin incidents, as well as their environmental and health effects in this country. HAB has been increasing rapidly along the Chinese coast since the 1970s, and at least 512 documented HAB events have occurred from 1952 to 2002 in the Chinese mainland. It has been found that PSP and DSP toxins are distributed widely along both the northern and southern Chinese coasts. The HAB and marine algal toxin events during the 1990s in China were summarized, showing that the HAB and algal toxins resulted in great damages to local fisheries, marine culture, quality of marine environment, and human health. Therefore, to protect the coastal environment and human health, attention to HAB and marine algal toxins is urgently needed from the environmental and epidemiological view.

A mechanistic model of algal photoinhibition induced by photodamage to Photosystem-II

Photoinhibition is a central problem for the understanding of plasticity in photosynthesis vs. irradiance response. It effectively reduces the photosynthetic rate. In this contribution, we present a mechanistic model of algal photoinhibition induced by photodamage to photosystem-II. Photosystem-IIs (PSIIs) are assumed to exist in three states: open, closed and inhibited. Photosynthesis is closely associated with the transitions between the three states. The present model is defined by four parameters: effective cross section of PSII, number of PSIIs, turnover time of electron transfer chains and the ratio of rate constant of damage to that of repair of D1 proteins in PSIIs. It gives a photosynthetic response curve of phytoplankton to irradiance (PI-curve). Without photoinhibition, the PI-curve is in hyperbola with the first three parameters. The PI-curve with photoinhibition can be simplified to the same form as the hyperbola by replacing either the number of PSIIs with the number of functional PSIIs or the turnover time of electron transfer chains with the average turnover time.

Impact of germanium on the growth of Pseudonitzschia pungens f. multiseries and the production of algal toxin

The impacts of germanic acid Ge(OH)(4) on the growth of Psuedonitzschia pungens f. multiseries and on the production of the algal toxin, domoic acid, were studied. The results showed that germanic acid in the range of concentrations could inhibit the growth of the algal cells and the inhibition was enhancing with the concentrations of germanic acid increasing. Germanic acid also could inhibit the production of the algal toxin, domoic acid in cells and the inhibition reached up to 100% at Ge/Si = 35. Based on the results, the mechanism was discussed.

Ecological environment changes in Daya Bay, China, from 1982 to 2004

Data collected from 12 marine monitoring stations in Daya Bay from 1982 to 2004 reveal a substantial change in the ecological environment of this region. The average N/P ratio increased from 1.377 in 1985 to 49.09 in 2004. Algal species changed from 159 species of 46 genera in 1982 to 126 species of 44 genera in 2004. Major zooplankton species went from 46 species in 1983 to 36 species in 2004. The annual mean biomass of benthic animals was recorded at 123.10 gm(2) in 1982 and 126.68 g m(2) in 2004. Mean biomass and species of benthic animals near nuclear power plants ranged froth 317.9 g m(2) in 1991 to 45.24 g m(2) in 2004 and from 250 species in 1991 to 177 species in 2004. A total of 12-19 species of hermatypic corals and 13 species of mangrove plants were observed in Daya Bay from 1984 to 2002. 2008 Elsevier Ltd. All rights reserved.

Influence of filtering and biodeposition by the cultured scallop Chlamys farreri on benthic-pelagic coupling in a eutrophic bay in China

In coastal ecosystems, suspension-cultured bivalve filter feeders may exert a strong impact on phytoplankton and other suspended particulate matter and induce strong pelagic-benthic coupling via intense filtering and biodeposition. We designed an in situ method to determine spatial variations in the filtering-biodeposition process by intensively suspension-cultured scallops Chlamys farreri in summer in a eutrophic bay (Sishili Bay, China), using cylindrical biodeposition traps directly suspended from longlines under ambient environmental conditions. Results showed that bivalve filtering-biodeposition could substantially enhance the deposition of total suspended material and the flux of C, N and P to the benthos, indicating that the suspended filter feeders could strongly enhance pelagic-benthic coupling and exert basin-scale impacts in the Sishili Bay ecosystem. The biodeposition rates of 1-yr-old scallops varied markedly among culture sites (33.8 to 133.0 mg dry material ind.(-1) d(-1)), and were positively correlated with seston concentrations. Mean C, N and P biodeposition rates were 4.00, 0.51, 0.11 mg ind.-1 d-1, respectively. The biodeposition rates of 2-yr-old scallops were almost double these values. Sedimentation rates at scallop culture sites averaged 2.46 times that at the reference site. Theoretically, the total water column of the bay could be filtered by the cultured scallops in 12 d, with daily seston removal amounting to 64%. This study indicated that filtering-biodeposition by suspension-cultured scallops could exert long-lasting top-down control on phytoplankton biomass and other suspended material in the Sishili Bay ecosystem. In coastal waters subject to anthropogenic N and P inputs, suspended bivalve aquaculture could be advantageous, not only economically, but also ecologically, by functioning as a biofilter and potentially mitigating eutrophication pressures. Compared with distribution-restricted wild bivalves, suspension-cultured bivalves in deeper coastal bays may be more efficient in processing seston on a basin scale.

Impact of astaxanthin-enriched algal powder of Haematococcus pluvialis on memory improvement in BALB/c mice

The impact of astaxanthin-enriched algal powder on auxiliary memory improvement was assessed in BALB/c mice pre-supplemented with different dosages of cracked green algal (Haematococcus pluvialis) powder daily for 30 days. The supplemented mice were first tested over 8 days to find a hidden platform by swimming in a Morris water maze. Then, for 5 days, the mice were used to search for a visible platform in a Morris water maze. After that, the mice practised finding a safe place-an insulated platform in a chamber-for 2 days. During these animal experimental periods, similar algal meals containing astaxanthin at 0, 0.26, 1.3 and 6.4 mg/kg body weight were continuously fed to each group of tested mice. Profiles of latency, distance, speed and the direction angle to the platforms as well as the diving frequency in each group were measured and analyzed. The process of mice jumping up onto the insulated platform and diving down to the copper-shuttered bottom with a 36 V electrical charge were also monitored by automatic video recording. The results of the Morris maze experiment showed that middle dosage of H. pluvialis meals (1.3 mg astaxanthin/kg body weight) significantly shortened the latency and distance required for mice to find a hidden platform. However, there was no obvious change in swim velocity in any of the supplemented groups. In contrast, the visible platform test showed a significant increase in latency and swim distance, and a significant decrease in swim speed for all groups of mice orally supplemented with H. pluvialis powder compared to the placebo group (P < 0.05 or P < 0.01). Mice supplemented with the algal meal hesitantly turned around the original hidden platform, in contract to mice supplemented with placebo, who easily forgot the original location and accepted the visible platform as a new safe place. These results illustrate that astaxanthin-enriched H. pluvialis powder has the auxiliary property of memory improvement. The results from the platform diving test showed that the low and middle dosage of H. pluvialis powder, rather that the high dosage, increased the latency and reduced the frequency of diving from the safe insulated platform to the electrically stimulated copper shutter, especially in the low treatment group (P < 0.05). These results indicate that H. pluvialis powder is associated with dose-dependent memory improvement and that a low dosage of algal powder (<= middle treatment group) is really good for improving the memory.

Methane emissions by alpine plant communities in the Qinghai-Tibet Plateau

For the first time to our knowledge, we report here methane emissions by plant communities in alpine ecosystems in the Qinghai-Tibet Plateau. This has been achieved through long-term field observations from June 2003 to July 2006 using a closed chamber technique. Strong methane emission at the rate of 26.2 +/- 1.2 and 7.8 +/- 1.1 mu g CH4 m(-2) h(-1) was observed for a grass community in a Kobresia humilis meadow and a Potentilla fruticosa meadow, respectively. A shrub community in the Potentilla meadow consumed atmospheric methane at the rate of 5.8 +/- 1.3 mu g CH4 m(-2) h(-1) on a regional basis; plants from alpine meadows contribute at least 0.13 Tg CH4 yr(-1) in the Tibetan Plateau. This finding has important implications with regard to the regional methane budget and species-level difference should be considered when assessing methane emissions by plants.