Heavy metal contamination along the China coastline: A comprehensive study using Artificial Mussels and native mussels.

A comprehensive study was carried out to assess metal contamination in five cities spanning from temperate to tropical environment along the coastal line of China with different hydrographical conditions. At each of the five cities, Artificial Mussels (AM) were deployed together with a native species of mussel at a control site and a polluted site. High levels of Cr, Cu and Hg were found in Qingdao, high level of Cd, Hg and Pb was found in Shanghai, and high level of Zn was found in Dalian. Furthermore, level of Cu contamination in all the five cities was consistently much higher than those reported in similar studies in other countries (e.g., Australia, Portugal, Scotland, Iceland, Korea, South Africa and Bangladesh). Levels of individual metal species in the AM showed a highly significant correlation with that in the native mussels (except for Zn in Mytilus edulis and Cd in Perna viridis), while no significant difference can be found between the regression relationships of metal in the AM and each of the two native mussel species. The results demonstrated that AM can provide a reliable time-integrated estimate of metal concentration in contrasting environments over large biogeographic areas and different hydrographic conditions, and overcome the shortcomings of monitoring metals in water, sediment and the use of biomonitors.

Coralslurrinella hongkonensis gen. nov., sp. nov., a novel bacterium in the family Psychromonadaceae, isolated from the coral Platygyra carnosus.

A novel bacterial strain, JLT2006T, was isolated from the scleractinian coral Platygyra carnosus, located in Hong Kong, China. Cells of this strain were Gram-negative, rod-shaped or oval-shaped and motile by the means of polar flagella. They formed faint-yellow, round colonies on marine agar medium. Phylogenetic analyses based on the 16S rRNA gene sequence indicated that the strain JLT2006T belonged to the class Gammaproteobacteria and was most closely related to Alteromonas-like bacteria of the genera Psychromonas, Pseudoalteromonas, Moritella, Shewanella and Ferrimonas, with less than 93 % sequence similarity. The predominant fatty acids were identified as C18:1x7c/C18:1x6c (23.0 %), C16:1x7c/C16:1x6c (18.2 %) and C16:0 (16.4 %). The quinone was menaquinone-7 (100 %). The polar lipids were determined to be phosphatidylglycerol, phosphatidylethanolamine, phospholipid, glycolipid and lipid. The genomic DNA G?C content was 40.3 mol%. Based on the 16S rRNA gene sequence as well as the physiological and biochemical features that separate the strain JLT2006T from other recognized bacteria, a novel species of a new genus with the name Coralslurrinella hongkonensis gen. nov., sp. nov. is proposed. The type strain is JLT2006T (=JCM 18796T = CGMCC 1.10992T).

Polybrominated diphenyl ethers (PBDEs) alter larval settlement of marine intertidal organisms across three phyla via reducing bacterial abundance on the biofilms.

Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants over the last three decades, and are now ubiquitous in the marine environment. While the harmful effects of PBDEs on the abnormal development and reproductive impairment in mammals and fish are well documented, the effects on marine invertebrates remain virtually unknown. Using three model intertidal species accross three phyla, including the polychaete Hydroides elegans (Phylum Annelida), the gastropod Crepidula onyx (Phylum Mollusca), and the barnacle Balanus amphitrite (Phylum Arthopoda), this study demonstrated that (a) chronic exposure to BDE-47 (at spiking concentrations up to 1000 ng L(-1)) throughout the entire larval stage did not affect settlement, development or growth of all three species per se, despite bioaccumulation was clearly evident (measured body burden ranging from approximately 7000 to 13 000 ng BDE-47 g(-1) lipid), and (b) BDE-47, at measured concentrations of 15 and 113 ng g(-1) lipid, reduced the bacterial abundance in biofilms and resulted in a concomitant change in larval settlement pattern of all the model intertidal species across three phyla.

Changes in biofilm bacterial communities in response to combined effects of hypoxia, ocean acidification and nutrients from aquaculture activity in Three Fathoms Cove.

Anthropogenic nutrient enrichment results in hypoxia, ocean acidification and elevated nutrients (HOAN) in coastal environments throughout the world. Here, we examined the composition of biofilm bacterial communities from a nutrient-excessive fish farm with low dissolved oxygen (DO) and pH levels using 16S rRNA gene sequencing. HOAN was accompanied by higher bacterial diversity and richness, and resulted in an altered community composition than the control site. HOAN resulted in more Flavobacteriales, Rhizobiales, Epsilonproteobacteria and Vibrionales, but less Oceanospirillales and Alteromonadales. Photobacterium sp. and Vibrio sp. were mostly found to be exclusive to HOAN conditions, suggesting that HOAN could possibly proliferate the presence of these potential pathogens. Our study suggests the complexity of bacterial communities to hypoxia and acidification in response to increased nutrient loads, along with identities of nutrient, oxygen and pH-susceptible bacterial groups that are most likely affected under this ocean trend.

Transgenerational impairments of reproduction and development of the marine invertebrate Crepidula onyx resulted from long-term dietary exposure of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47).

Polybrominated diphenyl ethers have become ubiquitous in the environment and elevated concentrations have often been found in marine organisms. Using the gastropod Crepidula onyx as a study model, this multigenerational study sets out to test the hypotheses that 1) parental dietary exposure to environmentally realistic levels of 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) would lead to transgenerational impairments on fitness traits of marine invertebrates, and 2) the organisms might develop adaptation/acclimation after exposure for one or more generations. F0 generation of C. onyx was fed with the dinoflagellate Isochrysis galbana encapsulated with two concentrations of BDE-47 (1.78 and 16.0 ng million cells-1, respectively), and half of the F1 offspring from the higher concentration treatment was returned to control condition (transgenerational group), while the other half received BDE-47 treatment continuously (continuous treatment group). Bioaccumulation and maternal transfer of BDE-47 were evident in all life stages of the F0 generation and in F1 eggs, respectively. Exposure to BDE-47 reduced fecundity, delayed sexual maturity, and impeded embryonic development in F0 to F2. In particular, developmental toxicity of F2 embryos was apparent in the transgenerational group, but not in the continuous treatment group, even when BDE-47 was not detected in the F2 embryos nor in their mothers and they have never been exposed to the chemical. This study also suggested that the offspring might have developed adaptation/acclimation to the exposure of BDE-47 within two generations of exposure, and that the physiological alterations associated with acclimation/adaptation might have hindered the normal larval development under a stress free condition. These findings highlighted the need for long-term multigenerational studies in the ecological risk assessment of chemicals alike.

A comparative study on metal contamination in Estero de Urias lagoon, Gulf of California, using oysters, mussels and artificial mussels: Implications on pollution monitoring and public health risk.

The profile of 11 trace metals in two commonly used biomonitors (the native oyster Crassostrea palmula and mussel Mytella strigata) from Estero de Urias lagoon, Gulf of California, were studied for six months, covering both dry and wet seasons. Metal concentrations in these two bivalves were compared with concentrations accumulated by Artificial Mussels (AMs) deployed alongside during the same period. Significant temporal variations in Cd, Cr and Mn were observed in both bivalve species and AMs. Temporal changes were observed for Fe in both bivalve species, Pb in oyster only and Cu in both AMs and oysters, revealing seasonal changes in inputs and/or chemical forms of these metals in the lagoon. Significant correlations for Cd, Cr and Cu were found in mussels and oysters, but their Co, Fe, Mn and Zn profiles were very different, despite these two species being taxonomically closely related and often used as biomonitors for metals. Interestingly, Hg and U were detected in AMs but not in oysters and mussels. The difference in metal profile in oysters, mussels and AMs revealed in the present study clearly showed that different biomonitors and AM take up metals differentially from the same environment, and metal profile in a single biomonitor or AM alone therefore, cannot provide a good estimate on metal concentrations in the ambient environment. As such, different biomonitors and AM should be used in metal monitoring, in order to provide a comprehensive picture on metal levels in aquatic ecosystems. Concentrations of Ni and Pb in oysters, and Cr, Fe and Mn in mussels were among the highest reported in coastal waters worldwide. Concentrations of Pb in oysters exceeded legal limits set for bivalve mollusks in EU. Concentrations of Cr in mussels and oysters exceeded or were very close to, respectively, the legal limit for fish, crab-meat, oysters, prawns, and shrimps in Hong Kong. The results indicate a potential public health risk on human consumption of oysters and mussels commonly harvested from the Estero de Urias lagoon, and corresponding pollution control measures are deemed necessary.

Contamination and risk implications of endocrine disrupting chemicals along the coastline of China: A systematic study using mussels and semipermeable membrane devices.

A systematic study has been carried out to assess the contamination of endocrine disrupting chemicals (EDCs) in five highly urbanized coastal cities spanning from temperate to subtropical environments along the coastline of China. In each of these cities, species of native mussels (Mytilus galloprovincialis, M. coruscus or Perna viridis) were deployed alongside with semipermeable membrane devices (SPMDs) for one month at a reference site and a polluted site. The level of 4-nonylphenol (4-NP), bisphenol A (BPA), 17ß-estradiol (E2) and 17α-ethynylestradiol (EE2) in SPMDs and transplanted mussels were determined and compared. The concentration of EDCs in mussels from polluted sites of Qingdao and Shenzhen ranged from 99.4±9.40 to 326.1±3.16ng/g dry wt. for 4-NP, Dalian and Shanghai from 170.3±4.00 to 437.2±36.8ng/g dry wt. for BPA, Dalian and Shenzhen from 82.9±3.03 to 315.6±6.50ng/g dry wt. for E2, and Shenzhen and Shanghai from 124.5±3.25 to 204.5±9.26ng/g dry wt. for EE2, respectively. These results demonstrate that concentrations of EDCs in mussels along the coastline of China are substantially higher than levels reported in mussels and seafood elsewhere. Despite high levels of EDCs and per capita seafood consumption in China, analysis indicated that 4-NP and BPA intake from mussels at polluted sites per se are still below the Tolerable Daily Intake (TDI). In contrast, the daily intake of E2 and EE2 (6.5 and 5.5µg/person/day, respectively) from mussel consumption exceeded the Acceptable Daily Intake (ADI) established by the WHO, USA and Australia by large margins, suggesting significant public health risks. A strong correlation was found between EDC concentrations in SPMDs and transplanted mussels, and the advantages of using mussels and SPMDs for monitoring EDCs in the aquatic environment are discussed.

Uptake and biotransformation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in four marine microalgae species.

Hydroxylated- and methoxylated- polybrominated diphenyl ethers (OH-PBDEs and MeO-PBDEs) are more toxic than PBDEs and occur widely in the marine environment, and yet their origins remain controversial. In this study, four species of microalgae (Isochrysis galbana, Prorocentrum minimum, Skeletonema grethae and Thalassiosira pseudonana) were exposed to BDE-47, which is synthetic and is the predominant congener of PBDEs in the environment. By chemical analysis after incubation of 2 to 6 days, the efficiency of uptake of BDE-47 and, more importantly, the potential of undergoing biotransformation to form OH-PBDEs and MeO-PBDEs by the microalgae were investigated. Growth rates of these axenic microalgae were not affected upon exposure to environmentally relevant concentrations (0.2-20 µg BDE-47 L-1), and accumulation ranged from 0.772 ± 0.092 µg BDE-47 g-1 lipid to 215 ± 54 µg BDE-47 g-1 lipid within 2 days. Debromination of BDE-47 and formation of BDE-28 occurred in all microalgae species (0.01 to 0.87%), but biotransformation to OH-PBDEs was only found in I. galbana upon exposure to extremely high concentration. The results of this study showed that biotransformation of microalgae species is unlikely an explanation for the OH-PBDEs and MeO-PBDEs found in the marine environment.

Adaptation and evolution of deep-sea scale worms (Annelida: Polynoidae): insights from transcriptome comparison with a shallow-water species.

Polynoid scale worms (Polynoidae, Annelida) invaded deep-sea chemosynthesis-based ecosystems approximately 60 million years ago, but little is known about their genetic adaptation to the extreme deep-sea environment. In this study, we reported the first two transcriptomes of deep-sea polynoids (Branchipolynoe pettiboneae, Lepidonotopodium sp.) and compared them with the transcriptome of a shallow-water polynoid (Harmothoe imbricata). We determined codon and amino acid usage, positive selected genes, highly expressed genes and putative duplicated genes. Transcriptome assembly produced 98,806 to 225,709 contigs in the three species. There were more positively charged amino acids (i.e., histidine and arginine) and less negatively charged amino acids (i.e., aspartic acid and glutamic acid) in the deep-sea species. There were 120 genes showing clear evidence of positive selection. Among the 10% most highly expressed genes, there were more hemoglobin genes with high expression levels in both deep-sea species. The duplicated genes related to DNA recombination and metabolism, and gene expression were only enriched in deep-sea species. Deep-sea scale worms adopted two strategies of adaptation to hypoxia in the chemosynthesis-based habitats (i.e., rapid evolution of tetra-domain hemoglobin in Branchipolynoe or high expression of single-domain hemoglobin in Lepidonotopodium sp.).

A novel approach for estimating the removal efficiencies of endocrine disrupting chemicals and heavy metals in wastewater treatment processes.

The wide occurrence of endocrine disrupting chemicals (EDCs) and heavy metals in coastal waters has drawn global concern, and thus their removal efficiencies in sewage treatment processes should be estimated. However, low concentrations coupled with high temporal fluctuations of these pollutants present a monitoring challenge. Using semi-permeable membrane devices (SPMDs) and Artificial Mussels (AMs), this study investigates a novel approach to evaluating the removal efficiency of five EDCs and six heavy metals in primary treatment, secondary treatment and chemically enhanced primary treatment (CEPT) processes. In general, the small difference between maximum and minimum values of individual EDCs and heavy metals measured from influents/effluents of the same sewage treatment plant suggests that passive sampling devices can smooth and integrate temporal fluctuations, and therefore have the potential to serve as cost-effective monitoring devices for the estimation of the removal efficiencies of EDCs and heavy metals in sewage treatment works.

Taxonomic and Functional Diversity of Soil and Hypolithic Microbial Communities in Miers Valley, McMurdo Dry Valleys, Antarctica.

The McMurdo Dry Valleys of Antarctica are an extreme polar desert. Mineral soils support subsurface microbial communities and translucent rocks support development of hypolithic communities on ventral surfaces in soil contact. Despite significant research attention, relatively little is known about taxonomic and functional diversity or their inter-relationships. Here we report a combined diversity and functional interrogation for soil and hypoliths of the Miers Valley in the McMurdo Dry Valleys of Antarctica. The study employed 16S rRNA fingerprinting and high throughput sequencing combined with the GeoChip functional microarray. The soil community was revealed as a highly diverse reservoir of bacterial diversity dominated by actinobacteria. Hypolithic communities were less diverse and dominated by cyanobacteria. Major differences in putative functionality were that soil communities displayed greater diversity in stress tolerance and recalcitrant substrate utilization pathways, whilst hypolithic communities supported greater diversity of nutrient limitation adaptation pathways. A relatively high level of functional redundancy in both soil and hypoliths may indicate adaptation of these communities to fluctuating environmental conditions.

Pyrosequencing of the bacteria associated with Platygyra carnosus corals with skeletal growth anomalies reveals differences in bacterial community composition in apparently healthy and diseased tissues.

Corals are rapidly declining globally due to coral diseases. Skeletal growth anomalies (SGA) or "coral tumors" are a group of coral diseases that affect coral reefs worldwide, including Hong Kong waters in the Indo-Pacific region. To better understand how bacterial communities may vary in corals with SGA, for the first time, we examined the bacterial composition associated with the apparently healthy and the diseased tissues of SGA-affected Platgyra carnosus using 16S ribosomal rRNA gene pyrosequencing. Taxonomic analysis revealed Proteobacteria, Bacteroidetes, Cyanobacteria, and Actinobacteria as the main phyla in both the apparently healthy and the diseased tissues. A significant difference in the bacterial community composition was observed between the two conditions at the OTU level. Diseased tissues were associated with higher abundances of Acidobacteria and Gemmatimonadetes, and a lower abundance of Spirochaetes. Several OTUs belonging to Rhodobacteraceae, Rhizobiales, Gammaproteobacteria, and Cytophaga-Flavobacterium-Bacteroidetes (CFB) were strongly associated with the diseased tissues. These groups of bacteria may contain potential pathogens involved with the development of SGA or opportunistic secondary or tertiary colonizers that proliferated upon the health-compromised coral host. We suggest that these bacterial groups to be further studied based on inoculation experiments and testing of Koch's postulates in efforts to understand the etiology and progression of SGA.

Interactive effects of hypoxia and polybrominated diphenyl ethers (PBDEs) on microbial community assembly in surface marine sediments.

Hypoxia alters the oxidation-reduction balance and the biogeochemical processes in sediments, but little is known about its impacts on the microbial community that is responsible for such processes. In this study, we investigated the effects of hypoxia and the ubiquitously dispersed flame-retardant BDE47 on the bacterial communities in marine surface sediments during a 28-days microcosm experiment. Both hypoxia and BDE47 alone significantly altered the bacterial community and reduced the species and genetic diversity. UniFrac analysis revealed that BDE47 selected certain bacterial species and resulted in major community shifts, whereas hypoxia changed the relative abundances of taxa, suggesting slower but nonetheless significant community shifts. These two stressors targeted mostly different taxa, but they both favored Bacteroidetes and suppressed Gammaproteobacteria. Importantly, the impacts of BDE47 on bacterial communities were different under hypoxic and normoxic conditions, highlighting the need to consider risk assessments for BDE47 in a broader context of interaction with hypoxia.

Polybrominated diphenyl ethers do not affect metamorphosis but alter the proteome of the invasive slipper limpet Crepidula onyx.

Man-made polybrominated diphenyl ethers (PBDEs) used as flame retardants in various consumer products may be harmful to marine organisms. Larvae of some marine invertebrates, especially invasive species, can develop resistance to PBDEs through altered protein expression patterns or proteome plasticity. This is the first report of a proteomics approach to study BDE-47 induced molecular changes in the invasive limpet Crepidula onyx. Larvae of C. onyx were cultured for 5 days (hatching to metamorphosis) in the presence of BDE-47 (1 µg L(-1)). Using a 2-DE proteomics approach with triple quadrupole and high-resolution TOF-MS, we showed that BDE-47 altered the proteome structure but not the growth or metamorphosis of C. onyx larvae. We found eight significant differentially expressed proteins in response to BDE-47, deemed the protein expression signature, consisting of cytoskeletal, stress tolerance, metabolism and energy production related proteins. Our data suggest C. onyx larvae have adequate proteome plasticity to tolerate BDE-47 toxicity.

Bacteria associated with skeletal tissue growth anomalies in the coral Platygyra carnosus.

Scleractinian corals with growth anomalies, often referred to as 'tumors', have been reported globally. A recent survey of Hong Kong waters showed that > 60% of Platygyra carnosus colonies developed tumors. Here we report for the first time, the bacterial community associated with tumors in P. carnosus over different seasons and locations in Hoi Ha Wan Marine Park and Port Shelter. Culture-based methods for strain isolation and molecular techniques of 16S rRNA analysis for strain identification were used, as well as the culture-independent technique terminal-restriction fragment length polymorphism. We tested the hypothesis that the community composition would be considerably different between healthy and tumor corals and aimed to investigate whether potential differences because of tumors would override the seasonal and spatial influences. Our analysis detected only minor differences between the communities associated with the healthy and tumor corals, indicating that tumors are not associated with major changes in the bacterial community structure. In contrast, community structure was strongly influenced by the location and season, with greater Alphaproteobacteria diversity in the winter than in the summer. This study demonstrated that the coral-associated bacterial community composition was more related to environmental variables (i.e. season and location) than to disease (i.e. tumor).