Hongfa Wang

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.

The biodiversity of macrobenthos from Jiaozhou Bay

Abstract The current situation of the animal species biodiversity of macrobenthic fauna in the Jiaozhou Bay (South Shandong Peninsula, Yellow Sea) is reported in the present paper, based on the data from 15 investigation cruises carried out from February 1998 to November 2001. In analyzing the data, the Shannon-Wiener index, and species evenness and richness indices were used to study the trends of variation of the community structure, the species assemblages in the macrobenthic community, the dominant species, and the abundance of macrobenthic fauna in Jiaozhou Bay. A total of 322 species of macrobenthic animals were found in the bay, of which 133 species belong to 44 families of Polychaeta, while 92 species belong to 42 families of Crustacea. The average number of species per sample station ranged from 8 to 26. The Shannon-Wiener indices were very different among the samples, with the highest being recorded from Station 8 in November 2001, and the lowest from Station 9 in August 2001. The number of species, the Shannon-Wiener indices, and the species richness indices from Stations 7 and 9 were generally lower than those from other stations. This is because both the stations are situated at areas with a strong current and where the sediment is coarse sand. Although the richness index of species and the Shannon-Wiener index were high in Station 3, the Pielou evenness index was the lowest of all the sampling stations. This is because the station is located near the culture area of Ruditapes philippinarum , where a high abundance of clams caused low evenness. The results also revealed that the number of species and abundance greatly affected the biodiversity, and some environmental factors such as temperature, salinity, and primary productivity were also closely interrelated with biodiversity. Pollution and overexploitation caused by human activities were very important factors affecting macrobenthic biodiversity. In order to find the best way to enhance and protect living marine resources, the relationship between human activities and the biodiversity of macrobenthos in the Jiaozhou Bay should be studied further.

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.

Seasonal and spatial variations of macro- and megabenthic community characteristics in two sections of the East China Sea

In spring and summer 2011, the macro- and megabenthic fauna in two sections of the East China Sea were investigated using an Agassiz net trawl to detect the seasonal and spatial variations of benthic community characteristics and the relation to environmental variables. The total number of species increased slightly from spring (131 species) to summer (133) whereas the percentage of Mollusca decreased significantly. The index of relative importance (IRI) indicated that the top five important species changed completely from spring to summer. Species number, abundance and biomass in summer were significantly higher than in spring, but no significant difference was observed among areas (coastal, transitional and oceanic areas, divided basically from inshore to offshore). Species richness (d), diversity (H′) and evenness (J′) showed no significant seasonal or spatial variations. Cluster analysis and nMDS ordination identified three benthic communities from inshore to offshore, corresponding to the three areas. Analysis of Similarity (ANOSIM) indicated the overall significant difference in community structure between seasons and among areas. K-dominance curves revealed the high intrinsic diversity in the offshore area. Canonical correspondence analysis showed that the coastal community was positively correlated to total nitrogen and total organic carbon in spring, but negatively in summer; oceanic community was positively correlated to total nitrogen and total organic carbon in both seasons. Species such as Coelorhynchus multispinulosus, Neobythites sivicola, Lepidotrigla alata, Solenocera melantho, Parapenaeus fissuroides, Oratosquilla gonypetes and Spiropagurus spiriger occurred exclusively in the offshore oceanic area and their presence may reflect the influence of the offshore Kuroshio Current.

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.

Spatiotemporal patterns of the macrofaunal community structure in the East China Sea, off the coast of Zhejiang, China, and the impact of the Kuroshio Branch Current

The Kuroshio Current intrudes in the bottom layer of the East China Sea continental shelf from the northeast of Taiwan via two bottom branches named the Nearshore Kuroshio Branch Current (NKBC, along the 60 m isobath) and the Offshore Kuroshio Branch Current (OKBC, along the 100 m isobath). However, knowledge on the macrofaunal responses to these bottom branches is limited. This study examined the variations in the benthic macrofaunal community in a section of the East China Sea under the influence of the NKBC. Seven sites corresponding to three regions (the west, middle and east region) were sampled using an Agassiz trawl net at a monthly rate from February to November 2015 (except in August). A total of 270 macrofaunal species were collected in this study. Cluster analysis and nMDS ordination revealed three communities: the inshore, Kuroshio and offshore communities, roughly corresponding to the west, middle and east of NKBC route. Significant differences in the species composition (one-way PERMANOVA) and diversity indices (one-way ANOVA) among the regions and communities were observed, while no statistically significant difference among the months was detected. The indicator species also varied among the communities, with Sternaspis scutata and Odontamblyopus rubicundus dominating the inshore community, Camatopsis rubida, Schizaster lacunosus and Craspidaster hesperus dominating the Kuroshio community, and Portunus argentatus, Champsodon snyderi and Coelorinchus multispinulosus dominating the offshore community. Some rare species (e.g., Neobythites sivicola) may indicate the passage of the NKBC better than the indicator species. A redundancy analysis was used to describe the relationship between the macrofaunal species and environmental variables in this study. Water depth and turbidity played important roles in the distribution of the macrofauna. S. scutata and O. rubicundus were associated with high turbidity and shallow depth, while Plesionika izumiae and P. argentatus were associated with low turbidity and deep depth. This study outlines the impact of the NKBC on the distribution patterns of the macrofaunal community of the East China Sea. More studies are needed to understand the detailed interactions between macrofauna and the NKBC in the future.

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.