This study investigated the trace element bioaccumulation capacity of the Mediterranean seagrass Posidonia oceanica, and its suitability as a bioindicator of contamination in water and sediments. Results showed that P. oceanica leaves accumulate higher concentrations of Ni and Zn. Since P. oceanica regenerates its leaves periodically, the higher concentrations in aerial organs may suggest a “removal” strategy according to which P. oceanica accumulates greater concentrations of trace elements in its temporary organs. In turn, P. oceanica seems to adopt an exclusion strategy for toxic non-essential elements (As, Cr, Pb). Results showed also that P. oceanica organs are correlated with As, Cd, Cu, Ni, and Zn concentrations in sediments. No significant relationship was found between P. oceanica and water. This study showed that P. oceanica may adopt different tolerance strategies compared to mainland-rooted macrophytes, and its possible use as a bioindicator of trace elements in sediments should be considered.

Phytoplankton and shellfish samples collected periodically from 5 representative mariculture zones around the Bohai Sea, Laishan (LS), Laizhou (LZ), Hangu (HG), Qinhuangdao (QHD) and Huludao (HLD), were analysed for paralytic shellfish toxins (PSTs) using an high-performance liquid chromatography (HPLC) method. Toxins were detected in 13 out of 20 phytoplankton samples, and N-sulfocarbamoyl toxins (C1/2) were predominant components of PSTs in phytoplankton samples with relatively low toxin content. However, two phytoplankton samples with high PST content collected from QHD and LS had unique toxin profiles characterized by high-potency carbamoyl toxins (GTX1/4) and decarbamoyl toxins (dcGTX2/3 and dcSTX), respectively. PSTs were commonly found in shellfish samples, and toxin content ranged from 0 to 27.6nmol/g. High level of PSTs were often found in scallops and clams. Shellfish from QHD in spring, and LZ and LS in autumn exhibited high risks of PST contamination.

In the present study, the concentrations and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in the water and surface sediments from the Chabahar Bay, Oman Sea, were investigated in May (premonsoon) and December (postmonsoon) 2012. The concentrations of PAHs in the surface water samples ranged from 1.7 to 2.8ngl−1 and from 0.04 to 59.6ngl−1 in pre- and postmonsoon, respectively. In general, the PAH levels of the water samples from Chabahar Bay were higher in postmonsoon than in premonsoon (p<0.05). The concentrations of PAHs in the sediment samples varied from undetectable levels to 92.8ngg−1 d.w. in both seasons. The seasonal comparison of the results in sediment samples showed that the overall concentration of PAH compounds was higher in the postmonsoon season (p<0.05).

Little is known regarding phytoremediation of radionuclides from soil; even less is known about radionuclide contamination and removal in tropical ecosystems such as mangrove forests. In mangrove forests in Pattani Bay, Thailand, 18 plant species from 17 genera were evaluated for radionuclide concentrations within selected plant parts. Two shrub species, Avicennia marina and Pluchea indica, accumulated the highest 232Th (24.6Bqkg−1) and 40K (220.7Bqkg−1) activity concentrations in roots, respectively. Furthermore, the aquatic species Typha angustifolia accumulated highest 232Th, 40K and 226Ra activity concentrations (85.2, 363.5, 16.6Bqkg−1, respectively) with the highest transfer factors (TFs) (3.0, 2.0, 5.9, respectively) in leaves. Leaves of T. angustifolia had an absorbed dose rate in air (D) over the recommended value (74.8nGyh−1) that was considered sufficiently high to be of concern for human consumption.

Surface sediments were collected from Vellar and Coleroon estuaries for determine sediment texture, calcium carbonate, organic matter and heavy metals. Pollution indices such as pollution load index (PLI), contamination factor (CF), enrichment factor (EF) and geo-accumulation index (Igeo) were done for this study to know the level of heavy metals pollution in the estuarine ecosystem. Pearson correlation matrix and factor were used to assess the relationship and source of heavy metals in the estuarine sediments. The results of PLI values reveal that the study area was polluted by all the heavy metals. The calculated values of CF and Igeo followed the decreasing order Cu>Ni>Pb>Co>Cr>Zn>Mn>Fe and illustrate that Cu, Ni and Pb are contaminated due to anthropogenic sources in both estuaries. Correlation and factor analysis suggest that FeMn oxyhydroxides, organic matter and fine particles are responsible for high concentration of heavy metals.

Harmful algal blooms (HABs) have broken out frequently throughout the world in recent decades; they are caused by the rapid multiplication of algal cells in near-coastal waters polluted with nitrogen and phosphorus and greatly affect the quality of marine water and human health. Over the past several decades, climate change and increasing environmental degradation have provided favourable growth conditions for certain phytoplankton species. Therefore, it is essential to rapidly identify and enumerate harmful marine algae to control these species. In this study, quantitative PCR (qPCR) was used to detect four representative species of HABs that are widespread in the marine water of Hong Kong, namely, Alexandrium catenella, Pseudo-nitzschia spp., Karenia mikimotoi and Heterosigma akashiwo. We applied qPCR with the dye SYBR Green to detect Alexandrium spp. and Pseudo-nitzschia spp. and used TaqMan probe for the enumeration of Karenia mikimotoi and Heterosigma akashiwo. The total genomic DNA of these algae from Hong Kong marine water was extracted successfully using the CTAB method, and for each kind of alga, we constructed a ten-fold series of recombinant plasmid solutions containing certain gene fragments of 18S rDNA and ITS1-5.8S-ITS2 as standard samples. Ten-fold dilutions of the DNA of known numbers of the extracted algal cells were also used to create an additional standard curve. In this way, the relationship between the cell number and the related plasmid copy number was established. The qPCR assay displayed high sensitivity in monitoring marine water samples in which the low concentrations of harmful algae were not detected accurately by traditional methods. The results showed that the cell numbers of the four species were all in low abundance. For Alexandrium catenella, the cell abundances at 12 sites ranged from 3.8×102 to 4.3×103cellsL−1, while H. akashiwo, K. mikimotoi and Pseudo-nitzschia ranged from 1.1×102 to 1.3×103, from 23 to 6.5×102 and from 45 to 3.3×103cellsL−1, respectively. The concentrations of these algae were much lower than those observed during outbreaks of HABs in Hong Kong. These results may be useful for local aquaculture development and may provide effective suggestions and a theoretical basis for HAB monitoring and management.

Aggressive behavior is crucial for maintaining social hierarchy in anemonefish. Endocrine disrupting chemicals such as EE2 may affect fish social hierarchy via disrupting their aggression. In this study, we aimed to characterize the effects of 17α-ethinylestradiol (EE2) on aggressive behavior and social hierarchy in the false clown anemonefish (Amphiprion ocellaris). In the laboratory experiment, juvenile anemonefish were randomly distributed to separated tanks to form small colonies of three individuals and were fed with EE2-dosed diet (100ng/g food) or a control diet for 90d. Through the experiment, each tank was videotaped and behavioral indicators of social status, including aggressive behavior, submissive response, and shelter utilization, were quantitatively analyzed from the videos. The EE2 exposure caused a higher frequency of intra-colonial aggressive interactions and a less stable social hierarchy. Our findings demonstrate the importance of examining the effects of endocrine disrupting chemicals on the social behavior of coral reef fish.

Nutrient and heavy metal (Fe, Mn, Ni, Cu, Pb, Zn, Cr, Cd and As) concentrations in porewater in sediment cores and their diffusive benthic fluxes were investigated in Daya Bay, South China, to study the accumulation and transfer of nutrients/metals at the sediment-water interface, and to discuss the impact of human activities on nutrients/metals. Nutrients and heavy metals displayed different profiles in porewater, which was mainly attributed to the distinct biogeochemical conditions in sediments. Total mean fluxes of nutrients (except NO3 and NO2) and metals in study area were positive, indicating nutrients and metals diffused from the sediment to overlying water, and sediment was generally the source of nutrients/metals. Human activities and the weak hydrodynamic force made nutrients/metals accumulate in sediment, so the sediment should be paid more attention to as the endogenesis of contamination in Daya Bay waters.

Residence times of microplastics were estimated based on the dependence of meso- and macrolitter residence times on their upward terminal velocities (UTVs) in the ocean obtained by one- and two-year mark-recapture experiments conducted on Wadahama Beach, Nii-jima Island, Japan. A significant linear relationship between the residence time and UTV was found in the velocity range of about 0.3–0.9ms−1, while there was no significant difference between the residence times obtained in the velocity range of about 0.9–1.4ms−1. This dependence on the UTV would reflect the uprush-backwash response of the target items to swash waves on the beach. By extrapolating the linear relationship down to the velocity range of microplastics, the residence times of microplastics and the 1D onshore-offshore diffusion coefficients were inferred, and are one to two orders of magnitude greater than the coefficients of the macroplastics.

We report a novel and inexpensive method to provide high resolution vertical measurements of temporally integrated organic contaminants in surface and sub-surface waters in polluted coastal environments. It employs a strip of polyethylene deployed as a passive sampler. Verifications are confirmed via conventional spot sample analyses and against Performance Reference Compound (PRC) calibration methods. Analytes targeted include 16 Polycyclic Aromatic Hydrocarbons, 15 personal care products, 8 organophosphorus flame retardants, 4 antifouling ‘booster’ biocides and 15 n-alkanes. Whilst all contaminants typically revealed homogeneous concentrations from 10 cm to 3 m depth in the selected harbour (<30% variations), many increased sharply at the air-sea interface. The passive sampler was shown to afford better resolution than could be achieved using conventional analytical techniques at the surface microlayer (SML). Whilst hydrophobicity appeared to be a key factor for the enrichment of many determinants, less correlation was found for the emerging contaminants.