Zhinan Zhang

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.

Large-scale patterns in the community structure and biodiversity of freeliving nematodes in the Bohai Sea, China

Freeliving marine nematodes were sampled on two occasions from an extensive grid of 20 stations in the Bohai Sea and its approaches. Differences within stations between sampling periods were small, resulting from small changes in abundance of dominant species. Differences between stations were significant, and were used to cluster stations into groups with similar species composition. These station groupings revealed a weak faunal gradient leading from the mouth of the Huanghe (Yellow River) to the Bohai Strait. Analyses relating faunal composition to environmental variables showed that there were significant differences in environmental variables between faunally-defined groups of stations. The variables most closely correlated with community structure were silt/clay and sand, depth, phaeopigment concentrations below the sediment surface, organic content and arsenic. These reflect natural processes within the Bohai Sea. A suite of univariate measures were related to distance from the river mouth, with a major discontinuity about 120 km into the Bohai Sea. Comparison of values of the biodiversity measures average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) suggest that the meiobenthos of the Bohai Sea as a whole is not under major pollution stress.

New species of free-living marine nematodes from the Yellow Sea, China

Three new species of free-living marine nematodes: Oncholaimus multisetosus sp. nov., Sabatieria stenocephalus sp. nov. and Setosabatieria coomansi sp. nov. from the Yellow Sea, China are described and illustrated. The male of Oncholaimus multisetosus sp. nov. is characterized by a tail sharply constricted at the junction of the conical and cylindrical sections; two circles of 12-15 pairs of circumcloacal setae each. In the female, the conical section of the tail gradually tapers in a cylindrical section. Sabatieria stenocephalus sp. nov. is characterized by the pronounced sharp-pointed anterior body, sclerotized tooth-like front edge of buccal cavity and 15 tubular-shaped precloacal supplements with the posterior five more closely spaced. Setosabatieria coomansi sp. nov. can be separated from the other species of the genus by the number (6-8) of cervical setae per file, the number of precloacal supplements (15) and the absence of central strips in spicules and leaf-like extensions of the cuticle lateral to the cloaca. Types are deposited in the College of Marine Life Sciences, Ocean University of China.

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.

Meiofauna and its sedimentary environment as an integrated indication of anthropogenic disturbance to sandy beach ecosystems

The accuracy and applicability of the Nematode/Copepod index (N/C) in monitoring the effects of environmental disturbances is controversial. In this study, we used an integrated approach that includes both meiofauna and the sedimentary environment to demonstrate a tourism-induced disturbance gradient among sampled beaches. We also analysed the relationships between meiofauna and environmental factors. The results showed that disturbed beaches were characterised by high values of meiofauna abundance, chlorophyll a content, total organic carbon content and N/C but lower levels of dissolved oxygen. The chlorophyll a and dissolved oxygen contents were found to be the most important factors for explaining the disturbance gradient amongst the beaches. The N/C index had a positive relationship with chlorophyll a and a negative relationship with dissolved oxygen. There was no significant relationship between N/C index and total organic carbon content.

Two new species of the genus Elzalia (Nematoda: Monhysterida: Xyalidae) from the Yellow Sea, China

Two new species of free-living marine nematodes of the genus Elzalia , Elzalia gerlachi sp. nov. and Elzalia striatitenuis sp. nov. from the Yellow Sea, China, are described and illustrated. Elzalia gerlachi sp. nov. is characterized by relatively large body length (1540–1740 μm in males; 1510–1780 μm in females), spicules 135–160 μm (3.33–3.90 anal body diameter) and complex gubernaculum. Elzalia striatitenuis sp. nov. is characterized by rather small body size (560–660 μm in males; 570–630 μm in females), short cephalic setae 2.5 μm long (21.4–31.3% of head diameter), spicules 65–85 μm (4.06–4.67 anal body diameter) and relatively simple gubernaculum. The two new species can be distinguished from other species of the genus by length and structure of spicules and gubernaculum. Pictorial and tabular keys to the genus are given.

Two new species of Xyalidae (Nematoda) from the Yellow Sea, China

Two new species of free-living marine nematodes, Daptonema longiapophysis sp. nov. and Cobbia sinica sp. nov. from the Yellow Sea, China are described and illustrated. Daptonema longiapophysis sp. nov. is characterized by spicules with a projection on the ventral and dorsal side respectively and the length of the gubernacular apophysis longer than the length of spicules. Cobbia sinica sp. nov. is characterized by one big dorsal tooth, long conico-cylindrical tail and gubernaculum with a small dorsal apophysis.

A new genus and new species of free-living marine nematodes from the Yellow Sea, China

A new genus and one new species of free-living marine nematodes Paramarylynnia gen. nov., Paramarylynnia subventrosetata sp. nov. from the Yellow Sea, China are described and illustrated. Paramarylynnia gen. nov. is characterized by a cuticle with transverse rows of even dots; absence of lateral differentiation; gubernaculum large and dilated at the distal end, no distal dentation; precloacal supplements absent; tail conico-cylindrical. The type species of Paramarylynnia gen. nov. is Paramarylynnia subventrosetata sp. nov.

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.