Xiaoshou Liu

Distribution and pollution assessment of heavy metals in surface sediments in the Yellow Sea.

Heavy metal concentrations in surface sediments at 56 stations during two cruises in the Yellow Sea in summer and winter, 2011 were analyzed by inductively coupled plasma-mass spectrometry. The pollution status was assessed via the Geoaccumulation index and Hankanson potential ecological risk index. Higher concentrations of heavy metals (except for Mn) were found in the central Southern Yellow Sea and the western Northern Yellow Sea. The higher contents of Mn were much closer to Shandong Peninsula. Correlation analyses indicated that Pb, Cu, Fe, Ni, Zn and Co probably had the same origin and were controlled by grain size and total organic carbon. Pollution assessment showed that most areas of the Yellow Sea were not or lowly contaminated with the exception of the northwest and south parts of the Southern Yellow Sea showing Cd-contamination. The pollution status of the Yellow Sea in summer was worse than that in winter.

Molecular detection of Candidatus Scalindua pacifica and environmental responses of sediment anammox bacterial community in the Bohai Sea, China.

The Bohai Sea is a large semi-enclosed shallow water basin, which receives extensive river discharges of various terrestrial and anthropogenic materials such as sediments, nutrients and contaminants. How these terrigenous inputs may influence the diversity, community structure, biogeographical distribution, abundance and ecophysiology of the sediment anaerobic ammonium oxidation (anammox) bacteria was unknown. To answer this question, an investigation employing both 16S rRNA and hzo gene biomarkers was carried out. Ca. Scalindua bacteria were predominant in the surface sediments of the Bohai Sea, while non-Scalindua anammox bacteria were also detected in the Yellow River estuary and inner part of Liaodong Bay that received strong riverine and anthropogenic impacts. A novel 16S rRNA gene sequence clade was identified, putatively representing an anammox bacterial new candidate species tentatively named “Ca. Scalindua pacifica”. Several groups of environmental factors, usually with distinct physicochemical or biogeochemical natures, including general marine and estuarine physicochemical properties, availability of anammox substrates (inorganic N compounds), alternative reductants and oxidants, environmental variations caused by river discharges and associated contaminants such as heavy metals, were identified to likely play important roles in influencing the ecology and biogeochemical functioning of the sediment anammox bacteria. In addition to inorganic N compounds that might play a key role in shaping the anammox microbiota, organic carbon, organic nitrogen, sulfate, sulfide and metals all showed the potentials to participate in the anammox process, releasing the strict dependence of the anammox bacteria upon the direct availability of inorganic N nutrients that might be limiting in certain areas of the Bohai Sea. The importance of inorganic N nutrients and certain other environmental factors to the sediment anammox microbiota suggests that these bacteria were active for the in situ N transforming process and maintained a versatile life style well adapted to the varying environmental conditions of the studied coastal ocean.

Subtropical meiobenthic nematode communities in Victoria Harbour, Hong Kong.

Wong, Y.S., Tam, N.F.Y., Lau, P.S., Xue, X.Z., 1995. The toxicity of marine sediments inVictoria Harbour, Hong Kong. Marine Pollution Bulletin 31, 464–470.Yap, C.K., Ismail, A., Tan, S.G., 2004a. Heavy metal (Cd, Cu, Pb and Zn) concentrationsin the green-lipped mussel Perna viridis (Linnaeus) collected from some wildand aquacultural sites in the west coast of Peninsular Malaysia. Food Chemistry84, 569–575.Yap, C.K., Ismail, A., Tan, S.G., Omar, H., 2002. Correlations between speciation of Cd,Cu, Pb and Zn in sediment and their concentrations in total soft tissue of green-lipped mussel Perna viridis from the west coast of Peninsular Malaysia.Environment International 28, 117–126.Yap, C.K., Tan, S.G., Ismail, A., Omar, H., 2004b. Allozyme polymorphisms and heavymetal levels in the green-lipped mussel Perna viridis (Linnaeus) collected fromcontaminated and uncontaminated sites in Malaysia. EnvironmentInternational 30, 39–46.Yeung, I.M.H., 1999. Multivariate analysis of the Hong Kong Victoria Harbour waterquality data. Environmental Monitoring and Assessment 59, 331–342.

Decadal change in sublittoral macrofaunal biodiversity in the Bohai Sea, China

The region of the Bohai Sea is among the most densely populated of any marginal sea worldwide, and the sea is of great commercial importance as one of the major fishing areas in China. In this study, sublittoral macrofaunal community data collected during the 2000s was integrated with historical data from the 1980s to 1990s to detect any change in biodiversity status over the past three decades. Biodiversity was assessed through species diversity, taxonomic relatedness and other measures of community structure. Different geographic locations had different scenarios of decadal biodiversity change. We observed a sustained increase in species diversity in Bohai Bay and a cyclic trajectory in Laizhou Bay. In the central part of the Bohai Sea, there was little change in species diversity, whereas taxonomic distinctness tended to increase. A test for departure from the expected value of taxonomic distinctness (Δ(+), Λ(+)) suggested that approximately one-fifth of the sampling stations were subjected to environmental stress and perturbation.

Marine meiobenthic and nematode community structure in Victoria Harbour, Hong Kong upon recovery from sewage pollution.

Sediment quality, meiofaunal and nematode communities were monitored across six time points at two inside-harbour and three outside-harbour sites over a three-year period in Victoria Harbour, Hong Kong, after the implementation of a sewage treatment project. Twenty-one meiofaunal groups comprising mainly free-living nematodes and harpacticoid copepods and 188 species of free-living nematodes were identified. The outside-harbour area had a more diverse and significantly different nematode community structure as compared to that in the inside-harbour area. Such spatial difference was highly correlated with the total Kjeldahl nitrogen content of the sediments. Over the study period, there was no significant improvement in sediment quality within the harbour. However, in the last sampling time, an increase in meiofaunal abundance and a closer similarity in nematode composition between one of the inside- and outside-harbour sites suggested signs of recovery of the meiofauna as a response to abatement of sewage pollution.

Response of meiofaunal community with special reference to nematodes upon deployment of artificial reefs and cessation of bottom trawling in subtropical waters, Hong Kong.

The response of meiofaunal communities, especially nematodes, upon the deployment of artificial reefs and cessation of bottom trawling at a designated Marine Protected Area (MPA) in Hong Kong was studied through comparison of meiofaunal samples collected inside and outside the MPA. Total organic carbon (TOC), total Kjeldahl nitrogen (TKN), total phosphorus (TP), water content and silt-clay fraction in sediments were also analyzed. The level of TOC and TKN, and total meiofaunal and nematode abundance were significantly lower inside than that outside the MPA. Multivariate analysis also indicated differences in community structure. Biological traits analysis revealed that the proportions of nematodes with a clavate tail shape, longer adult length, stout body shape and k-strategy life history were higher inside than that outside the MPA. Such changes in nematode community structure could be a result of the presence of the artificial reefs and closure of the MPA from bottom trawling.

Meiofauna with special reference to nematodes in trawling ground of subtropical Hong Kong.

Bottom trawling is one type of large-scale, anthropogenic dis-turbances in many of the world’s most productive marine environ-ments. The most evident effects of trawling on bottom sedimentare the alteration of distribution and abundance of target andnon-target species by means of non-selective, destructive trawlingmethods (Jennings and Kaiser, 1998; Hall, 1999; Kaiser and deGroot, 2000) and the strong collateral impacts on physical and bio-logical habitats(Freeseet al., 1999;Chuenpagdee et al., 2003).Suchdisturbance affects the diversity, abundance, size structure andproduction of benthic communities in our oceans (Kaiser andSpencer, 1996; Bergmann and Moore, 2001; Jennings et al., 2001,2002; Hermsen et al., 2003).In general, studies have suggested that frequent trawling dis-turbances may lead to the proliferation of smaller benthic species,with faster life histories, because they can withstand the mortalityimposed by trawling and benefit from reduced competition orpredation as populations of larger species are depleted (Jenningset al., 2001). In some areas, trawling has led to significant de-creases in infaunal biomass and production, and the abundanceof larger individuals is reduced more than smaller ones (Kaiserand Spencer, 1996). However, different benthic animals and sea-floor types are affected to different degrees. The greatest damageoccurs when animals come into contact with the hard parts of thefishing gear. Larger body-sized infauna are more susceptible todamage, particularly shallow burrowing species (Bergman andHup, 1992). Gilkinson et al. (1998) demonstrated that smallerbody-sized fauna are less susceptible to physical damage, as theyare pushed aside with fluidized sediments generated by the pres-sure wave that occurs in front of the moving trawl. Many ecolog-ical processes, such as production, are functions of body mass(Dickie et al., 1987). The smaller organisms that are less vulnera-ble to trawl disturbances generally have a higher annual repro-ductive output and higher intrinsic rates of natural increase,both of which decrease with increasing body size within a popu-lation (Brey, 1999; Collie et al., 2000; Duplisea et al., 2002). Bot-tom trawling can therefore lead to changes in communitycomposition and size structure through removal of large body-sized species and the largest individuals within populations (Ballet al., 2000).Meiofauna have been regarded as an important component inbenthic ecosystems due to their small size, high abundance andfast turnover rates (Heip et al., 1985; Coull, 1999). They are highquality food sources for fish, shrimp and mollusc larvae and impor-tant components in benthic food chains (Bell and Coull, 1978; Ellisand Coull, 1989; Gee, 1989; Coull, 1990). Hence, they play animportant role in trophic transfer in the marine ecosystem (War-wick, 1989). They also make use of organic detritus in sedimentsand are grazers of benthic bacteria and microalgae. Their grazingrate on bacteria is almost similar to the production of bacteria, sothey can regulate the productivity of bacteria (Montagna et al.,1995). Hence, they are important to the process of biological, geo-chemistry recycling. Compared with macrofauna, the easier fieldsampling, higher species richness, shorter life-cycles (3–5 genera-tionsper year) and lack of larval stages, make meiofauna importantin environmental assessment and ecosystem health monitoring(Coull and Chandler, 1992; Kennedy and Jacoby, 1999; Bongersand Ferris, 1999). In particular, they respond rapidly to environ-mental changes such as grain size, redox potential and food avail-ability (Soyer, 1985; Danovaro, 1996). They can resist disturbancesdue to trawling because they may be resuspended during thetrawling operation owing to their small body size (Gilkinsonet al., 1998). Their short life-cycles (Schwinghamer et al., 1986)would also allow them to withstand high mortality due totrawling.Although, there are numerous reports on the effects of bottomtrawling on sediment parameters and macrobenthic communi-ties, there were limited studies about meiofauna and nematodes(Pranovi et al., 2000; Schratzberger et al., 2002; Schratzbergerand Jennings, 2002; Lampadariou et al., 2005). Schratzbergerand Jennings (2002) revealed that the total nematode abundancewas significantly higher in an area exposed to medium level oftrawling disturbance in the North Sea. In temperate waters, Sch-ratzberger et al. (2002) found that seasonality may impact thenematode community structure, rather than caused by trawling,in a study in the North Sea. This study aimed to examine the sea-sonal changes of meiofauna with special reference to nematodesin trawling ground of Hong Kong, which is located in subtrophicwaters. The H

Sediment characteristics and benthic ecological status in contrasting marine environments of subtropical Hong Kong.

Sediment characteristics and benthic communities on a finer sampling scale in four contrasting environments in subtropical Hong Kong were analyzed in summer and winter 2012. In two harbour habitats which suffered from historic sewage pollution or hypoxic events, organic carbon, nutrient and trace metal content in the sediment were significantly higher than that in an offshore area and a marine reserve. The relatively low organic and nutrient content in the offshore habitat could be resulted from enhanced resuspension of such materials from the seabed owing to intense water mixing and disturbance caused by bottom trawling. The biotic indices AMBI and M-AMBI were shown to be useful in assessing the benthic ecological status of these habitats. Such indices can also be more sensitive than sediment physico-chemical parameters in differentiating the response of macrofauna to seasonal changes in the benthic environment.

Response of free-living marine nematodes to the southern Yellow Sea Cold Water Mass

The Yellow Sea Cold Water Mass is a remarkable seasonal hydrographic event in the bottom water of the Yellow Sea. In order to reveal the response of free-living marine nematodes to this event, community structure and biodiversity indices of nematodes were studied in June and November 2013. The dominant species were Dorylaimopsis rabalaisi, Spilophorella sp., Daptonema sp., Sabatieria sp. and Parasphaerolaimus sp. In terms of trophic structure, epigrowth feeders were the most dominant group. Correlation analysis showed that Shannon-Wiener diversity index had significantly negative correlation with sediment silt-clay percentage, organic matter content and water content. Results of BIOENV indicated that sediment phaeophorbide content, water content, bottom water salinity and temperature were the most important factors related to nematode community. In conclusion, community structure and biodiversity indices of nematodes were consistent in the two sampling seasons.

Quantitative distribution and functional groups of intertidal macrofaunal assemblages in Fildes Peninsula, King George Island, South Shetland Islands, Southern Ocean.

To evaluate spatial distribution pattern of intertidal macrofauna, quantitative investigation was performed in January to February, 2013 around Fildes Peninsula, King George Island, South Shetland Islands. A total of 34 species were identified, which were dominated by Mollusca, Annelida and Arthropoda. CLUSTER analysis showed that macrofaunal assemblages at sand-bottom sites belonged to one group, which was dominated by Lumbricillus sp. and Kidderia subquadrata. Macrofaunal assemblages at gravel-bottom sites were divided into three groups while Nacella concinna was the dominant species at most sites. The highest values of biomass and Shannon-Wiener diversity index were found in gravel sediment and the highest value of abundance was in sand sediment of eastern coast. In terms of functional group, detritivorous and planktophagous groups had the highest values of abundance and biomass, respectively. Correlation analysis showed that macrofaunal abundance and biomass had significant positive correlations with contents of sediment chlorophyll a, phaeophorbide and organic matter.