Baolin Zhang

Macrobenthic community structure and species composition in the Yellow Sea and East China Sea in jellyfish bloom

To understand the characteristics of macrobenthic structures and the relationship between environment and benthic assemblages in jellyfish bloom, we studied the macrobenthos and related environmental factors in the coastal waters of the Yellow Sea and East China Sea. Data were collected during two seasonal cruises in April and August of 2011, and analyzed with multivariate statistical methods. Up to 306 macrobenthic species were registered from the research areas, including 115 species of Polychaeta, 78 of Crustacea, 61 of Mollusca, 30 of Echinodermata, and 22 of other groups. Nine polychaete species occurred at frequencies higher than 25% from the sampling stations: Lumbrineris longifolia, Notomastus latericeus, Ninöe palmata, Ophelina acuminata, Nephtys oligobranchia, Onuphis geophiliformis, Glycera chirori, Terebellides stroemii, and Aricidea fragilis. Both the average biomass and abundance of macrobenthos are higher in August (23.8 g/m2 and 237.7 ind./m2) than those in April (11.3 g/m2 and 128 ind./m2); the dissimilarity of macrobenthic structures among stations is as high as 70%. In terms of the dissimilarity values, we divided the stations into four clusters in spring and eight in summer. The ABC curve shows that the macrofauna communities in high jellyfish abundance were not changed. Canonical correspondence analysis showed that depth, temperature, median grain size, total organic carbon of sediment and total nitrogen in sediment were important factors affecting the macrozoobenthic community in the study area.

Seasonal and spatial variations of macrobenthic community structure and diversity in the South Yellow Sea

Seasonal and spatial characteristics of the macrobenthic community in the South Yellow Sea were studied based on data from three voyages carried out in spring, summer and autumn, 2012. Twenty six stations were sampled and divided into three regions (west, middle and east region of South Yellow Sea). A total of 218 species were obtained with Polychaeta and Crustacea being the predominant groups. Mean abundance varied from 151.4 ind. m−2 in spring to 188 ind. m−2 in autumn showing an increasing trend with season, and mean biomass ranged from 12.1 g m−2 in spring to 33.4 g m−2 in summer. Mean secondary productivity varied from 0.21 g (AFDW)/(m2·month) in spring to 0.48 g (AFDW)/(m2·month) in summer. Biomass was significantly different among seasons, and number of species, secondary productivity and Shannon-Weiner index had significant differences among regions. Abundance, Pielous evenness index and average taxonomic distinctness were not significantly different among seasons nor regions. Overall significant differences of community structure among both seasons and regions were detected. Depth and the distance from shore were important factors influencing the distribution of macrobenthos in South Yellow Sea.

Status of macrobenthic diversity and distribution in Subei Shoal, China

Five cruise surveys were carried out in May–June 2013 to evaluate the status of macrobenthic diversity and distribution in Subei Shoal, China. Twenty-four stations were sampled and divided into four groups according to depth (5–10 m, 10–20 m, 20–30 m and 30–35 m). A total of 163 species were collected with Polychaeta dominating in species composition and abundance. All of the community parameters (abundance, biomass, mean species richness, Margalef richness index, Shannon-Wiener index and Pielous evenness) were not significantly different among the five cruises or among the four groups, except that Shannon-Wiener index at 5–10 m was significantly lower than that in other depth groups. No significant difference in community structure was detected among cruises, but when the data from the same station were pooled together, significant differences among stations were observed basically from inshore to offshore. The benthic opportunistic polychaetes amphipods index showed four stations having moderate ecological status in Subei Shoal. Canonical correspondence analysis showed that Sigambra bassi and Praxillella sp. were positively correlated with depth and salinity, and Paralacydonia paradoxa was positively correlated with dissolved oxygen.

Variations in macrobenthic community at two stations in the southern Yellow Sea and relation to climate variability (2000–2013)

Decadal variations (2000–2013) in the macrobenthic community of the southern Yellow Sea were investigated based on the analysis of the community at two stations located basically along the 70 m depth contour. Significant decadal variations in community structure were found through cluster analysis, nMDS ordination and one-way ANOSIM. SIMPER analysis showed that the decadal community variations could be roughly attributed to the decrease of two species of Mollusks (Thyasira tokunagai and Nucula tenuis) and the increase of one echinoderm (Ophiura sarsii vadicola), one polychaete (Notomastus latericeus) and one bivalve (Portlandia japonica) at both stations. Redundancy analysis showed that the Pacific Decadal Oscillation and the Southern Oscillation Index were significant climate indices influencing the macrobenthic community structure in the southern Yellow Sea. Most of the species collected in 2000s showed a positive correlation with Pacific Decadal Oscillation at both stations, especially for cold water species Thyasira tokunagai, while most species in 2010s were positively correlated to Southern Oscillation Index, e.g. Portlandia japonica and Notomastus latericeus at station 1 and Sigambra bassi and Aricidea fragilis at station 2.

Long-term variation of the macrobenthic community and its relationship with environmental factors in the Yangtze River estuary and its adjacent area

Using data from four periods from 1959 to 2015, we report the long-term variation of the macrobenthic community in the Yangtze River estuary and its adjacent area. In total, 624 species were collected, and Polychaeta was the dominant group. Significant differences between the four periods were found. The CCA (canonical correspondence analysis) and RDA (redundancy analysis) results revealed that temperature, salinity, and depth significantly influenced the macrobenthic communities (89.6% of the species-environment relationship variance was explained by the first two axes of CCA and 94.3% was explained by RDA). The results of K-dominance curves (the elevation increased over time), ABC (abundance/biomass comparison) curves (the W value changed from 0.311 to 0.167 during 1959 to 2014-2015) and the Shannon-Wiener index (log base=2; 2.29-5.03 in 1959, 2.86-4.55 in 2000-2001, 2.28-4.56 in 2011-2012, and 1.79-4.43 in 2014-2015) showed that the ecological status of the benthic study area was deteriorating.