冬夏季雷州半岛附近海域微微型光合浮游生物的类群变化及环境影响

2006年夏季和冬季对雷州半岛附近海域微微型光合浮游生物的类群数量与分布进行分析研究。结果表明:该海区微微型光合浮游生物的主要类群为聚球藻(Synechococcus)和微微型真核生物(pico-eukaryotes),二者在夏季的数量变化分别为(5.74±5.0)×104cell/ml和(2.33±1.82)×103cell/ml,冬季分别为(1.57±2.17)×103cell/ml和(4.17±4.40)×103cell/ml。聚球藻的丰度夏季高于冬季,高值区位于雷州湾海区;而微微型光合真核生物的丰度冬季高于夏季,冬季高值出现在雷州湾内D7站表层。雷州半岛西部海区微微型光合浮游生物的丰度夏、冬季变化比雷州湾附近海区明显,营养盐、温度、潮汐等是制约其数量变化的主要因子。

Status and distribution changes of the endangered Green Peafowl (Pavo muticus) in China over the past three decades (1990s-2017)

Background： Understanding the changes in population dynamics, including demographics, distribution and threats is essential for species status assessing.The endangered Green Peafowl （Povo muticus） has experienced sharp population declines and d stribution range diminishing both in China and Southeast Asia. Field population surveys have not been conducted in China since the 1990s, which hindered conservation planning and decision-making.Methods： With interview and line transects methods, we figured out the population and distribution changes of Green Peafowl across its historical ranges over the past three decades in China during 2014-2017.Results： The Green Peafowl once habituated in 54 counties in China. Nearly 60% of the distribution counties were lost in the past three decades, with the left 22 counties distributed in central, southern and western Yunnan, SW China. Population decrease detected in all distribution areas except for Shuangbai and Xinping county where more than 60% of the total population is located. Only about 30% of the former bird population were recorded with the same interviewing method as 20 years ago.Three birds, 1 carcass, 6 calls and 12 footprints were detected along the 865 km line transects, indicating extremely low encounter rate of Green Peafowl in field. Sharp decreases in flock sizes were also detected, from 8-20 birds per flock in the 1990s to 3-5 birds at present. Poaching and habitat conversion are two widespread and long-lasting threats, while poison tion affect regional population＇s survival. Large flocks of 18 ng caused mortality in the past and hydropower construc -27 birds were discovered in the field, which increases our confidence of population recovery of this endangered pheasant in China.Conclusions： Only interviewed bird number and counts based on line transects were presented in this study, without further population estimation due to limitation of the data sets. Although the actual population of this cryptic bird must be underestimated, dramatic population declines and distribution concentrations of the endangered Green Peafowl occurred over the past 30 years in China undoubtedly.

Spatial and seasonal variations in the trophic spectrum of demersal fish assemblages in Jiaozhou Bay, China

Trophic structure of fish communities is fundamental for ecosystem-based fisheries management, and trophic spectrum classifies fishes by their positions in food web, which provides a simple summary on the trophic structure and ecosystem function. In this study, both fish biomass and abundance trophic spectra were constructed to study the spatial and seasonal variations in the trophic structure of demersal fish assemblages in Jiaozhou Bay, China. Data were collected from four seasonal bottom trawl surveys in Jiaozhou Bay from February to November in 2011. Trophic levels(TLs) of fishes were determined by nitrogen stable isotope analysis. This study indicated that most of these trophic spectra had a single peak at trophic level(TL) of 3.4–3.7, suggesting that demersal fish assemblages of Jiaozhou Bay were dominated by secondary consumers(eg. Pholis fangi and Amblychaeturichthys hexanema). The spatial and seasonal variations of trophic spectra of Jiaozhou Bay reflected the influence of fish reproduction, fishing pressure and migration of fishes. Two-way analysis of variance(ANOVA) showed that seasonal variations in trophic spectra in Jiaozhou Bay were significant(P <0.05), but variations among different areas were not significant( P >0.05). The trophic spectrum has been proved to be a useful tool to monitor the trophic structure of fish assemblages. This study highlighted the comprehensive application of fish biomass and abundance trophic spectra in the study on trophic structure of fish assemblages.

Temporal and spatial variations in the distribution of macroalgal communities along the Yantai coast, China

To explore the impact of environmental variables on macroalgal communities, their temporal and spatial distributions were examined along the Yantai coast, China between April 2010 and March 2011. Macroalgae sampling was conducted monthly at four sites along the coast: Jiahe River estuary, Zhifu Island, Fisherman's Wharf, and Yangma Island. The species composition and abundance, and their relationship with environmental variables were assessed. Along the Yantai coast, 35 macroalgae species were identifi ed, including 24 Rhodophyta spp., 7 Chlorophyta, and 4 Phaeophyta spp. Highest species numbers were recorded in the summer at all sampling sites, except in the Jiahe River estuary. Macroalgae biomass was the greatest in the summer. Year-round, the highest species number and dry biomass recorded at Fisherman's Wharf and Yangma Island was attributed to the substrate type. In summer, Ulva pertusa Kjellman was the dominant species identifi ed along the Yantai coast, which indicates a risk of macroalgae blooms. Our results show that seawater temperature and nutrients appear to signifi cantly affect the temporal and spatial patterns of macroalgal abundance along the Yantai coast. The effects of environmental variables on the macroalgae on the Yantai coast need further study.

Spatial and temporal variation of fish assemblages in a subtropical small stream of the Huangshan Mountain

Spatial and temporal variation of fish assemblages were investigated seasonally from May 2007 to February 2008 across 11 study sites in a subtropical small stream, the Puxi Stream, of the Huangshan Mountain. Along the longitudinal gradient from headwater to downstream, fish species richness and abundance increased gradually, but then decreased significantly at the lower reaches. The highest species richness and abundance were observed in August and the lowest in February. Based on analysis of similarities （ANOSIM）, fish assemblages were significantly different in spatial variation but not in temporal variation. Although differences were observed both among sites and among stream orders, the lower R value in order-variation suggested stream order was not the optimal factor explaining the spatial variation of fish assemblages. In addition, dam construction did not significantly alter fish assemblages in the sites adjacent to and immediately downstream to dams. Using cluster analysis and non-metric Multi Dimensional Scaling analysis （NMS）, assemblages were separated into three groups at a Bray-Curtis similarity value of 42%： the upper, middle and lower groups. Following analysis of similarity percentages of species contributions （SIM- PER）, shifts in occurrence or abundance of S. curriculus, Z. platypus, R. bitterling and A. fasciatus contributed most to the differences amongst the three groups. Standard Deviation Redundancy Analysis （RDA） suggested that habitat structure （such as elevation, substrate, and flow velocity） contributed to the spatial and temporal pattem of fish assemblages in the Puxi Stream. In conclusion, the fish assemblages in Puxi Stream presented significant spatial but not temporal variation. Human disturbance has perhaps induced the decrease in species diversity in the lower reaches. However, no significant change was observed for fish assemblages in sites far from and immediately downstream from low-head dams [Current Zoology 56 （6）： 670-677, 2010].

Diversity and Evolution of Inflorescences in Celastrales

Inflorescences structures in context of their evolution have been conducted for 60 genera and 170 species of Celastrales （according to APG （Angiosperm Phylogeny Group） III 2009, almost 60% of genera and 15% of species from this taxon of the world flora）. There are two big groups of inflorescences in Celastrales-intercalary （more often） and terminal. For many genera of Celastrales both types of inflorescences can be observed, although the frequency of their occurrence varies. There is an important difference between two types of inflorescences： character of completion of the main axis （the terminal flower present or absent）. Flower opening can be in basipetal （Celastraceae, Brexia） or acropetal （Stackhousiaceae） order. Partial inflorescence types included： simple, compound or umbrellate dichasia, spike, raceme, thyrse. Simple flowers of Parnassia are large, nested on long reproductive shoots, emerging from a rosette, with amplexicaule leaf.

Effects of seasonal variations on soil microbial community composition of two typical zonal vegetation types in the Wuyi Mountains

Seasonal shifts play an important role in soil microbial community composition. This study examined the hypothesis that soil microbial community structure would vary with seasonal shifts in the Wuyi Mountains in Southeast China, and that two representative tree species （Castanopisi carlesii and Cunninghamia lanceolata） may have different soil microbial community composition. Phospholipids fatty acid analysis （PLFA） of seasonal shifts and was used to assess the effect vegetation types on soil microbial community structure. A total of 22 different PLFAs were identified from all the soil samples. The bacterial PLFAs accounted for 62.37% of the total PLFAs, followed by fungi （28.94%）, and the minimum was actinomycetes （6.41%）. Overall, the level of PLFAs in C. carlesii soil was greater than those in C. lanceolata soil, and significant differences were observed in some seasons. The amounts of total, bacteria, actinomycic and fungal PLFAs significantly changed with the seasons and followed a sequence order （summer 〉 autumn 〉 spring 〉 winter）. The bacteria/fungi PLFAs and G （＋）/G （-） PLFAs of two vegetation types also changed with the seasons and the ratios in summer and autumn were higher than those in spring and winter. The correlation analysis of microbial PLFAs and soil physicochemical properties showed that the total, bacteria, fungal, actinomycic, G （＋） and G （-） PLFAs were significantly positive correlation with TOC, TN, TP, TK and moisture content. We concluded that the seasonal shifts and vegetation types affect soil microbial community composition by changing the soil physicochemical properties.