[Diversity and faunal analysis of crustaceans in Potatso National Park, Shangri-La, China].

Potatso National Park was the first national park in mainland China, preceded by the earlier Bitahai Nature Reserve. Located in the northwest of Yunnan and on the southeast of Qinghai-Tibet plateau, Potatso is a typical low latitude and high elevation wetland nature reserve, with large areas of coniferous forest around alpine lakes and both wetland and water area ecosystems. In August, 2011, we undertook a survey of crustaceans in the park, sampling lakes, ponds, streams, and rivers throughout Potatso. We found a total of 29 species (including varieties) belonging to 24 genera and 11 families. Notable discoveries include Parartemiopsis sp, Arctodiaptomus parvispinus and Simocephalus congener, which are the first examples of these species to be recorded in China. Likewise, Gammarus bitaensis is a unique crustacean found only in Potatso National Park and Thermocyclops dumonti and Gammarus paucispinus are both endemic species to northwestern Yunnan. The overall faunal characteristics of crustaceans in the park also revealed several things about Potatso: (1) Cosmopolitan and Palaearctic elements reach 48.27% and 37.93%, clearly showing the Palaearctic element as the dominant fauna; (2) most of the crustacean, such as Arctodiaptomus parvispinus and Gammarus, are typical alpine types, confirming that Potatso has feature typical of alpine and plateau fauna; and (3) the proportion of endemic and rare crustacean species in Potatso National Park is approximately 10%, suggesting that the Potatso National Park in particular and the northwest of Yunnan in general have a unique geological and evolutionary history.

[Genetic diversity of eukaryotic picoplankton of eight lakes in Nanjing].

The method of terminal restriction fragment length polymorphism (T-RFLP) was used to study the genetic diversity of eukaryotic picoplankton (0.2-5.0 microm) in the pelagic and littoral zones in 8 lakes with different trophic status in Nanjing. The objectives of this study were to confirm the difference of the genetic diversity of eukaryotic picoplankton among lakes and the main factors affecting this difference. T-RFLP indicated that there were various fingerprints among lakes and zones. The average terminal restriction fragments (T-RFs) in the littoral and pelagic zones were 16.4 and 15.9, respectively. The littoral zone in Lake Nan and the pelagic zone in Lake Mochou had 30 T-RFs and 27 T-RFs, respectively. The T-RFs were the least abundant (10) in the pelagic zone in Lake Baijia with relatively low trophic status. The genetic diversity of eukaryotic picoplankton was higher in the littoral zone than that in the pelagic zone except Lake Pipa and Mochou. The cluster analysis indicated that the similarities of the littoral zones and the pelagic zones were very high except Lake Baijia, Qian and Nan. The canonical correspondence analysis between the genetic diversity of eukaryotic picoplankton and environmental factors revealed the concentration of chlorophyll a had the most important impact on the eukaryotic picoplankton communities (p = 0.004). The results indicated that the genetic diversity of eukaryotic picoplankton is affected by the trophic status and has the difference in the pelagic and littoral zones.

[Genetic diversity of eukarytic microplankton in different areas of Lake Taihu].

The methods of DGGE and cloning/sequencing were used to study the diversity and community structures of small planktons (0.8 - 20 microm) in different areas of Lake Taihu. DGGE indicated that there were markly various fingerprints in different areas and the diversities were higher in areas with low trophic status than those with relatively high trophic status. There were 23, 24 DGGE bands in East Taihu and Gonghu Bay, respectively (Shannon index were 3.135 and 3.178) and 18 bands in both Meiliang Bay and Wuli Bay (Both shannon index were 2.890). The result of cloning/sequencing indicated that there was a high diversity of small planktons in Lake Taihu and most of them phototrophic flagellate, heterotrophic flagellate, ciliate and fungi. There were various community structures in the three different clone libraries. In Meilang Bay, 28.6% OTUs(operational taxonomic unit)belonged to heterotrophic flagellate, followed by Cryptophyta (22.9%) and Chrysophyta (14.3%). In Central Lake, 25.7% OTUs belonged to Chrysophyta, followed by heterotrophic flagellate (20.0%) and Cryptophyta (14.3 %). In East Taihu, ciliates were the dominant group and only a few heterotrophic flagellates (40.9%) were detected. In addition, fungi were relatively abundant (12.2%) in this area.

Negative effects of Microcystis blooms on the crustacean plankton in an enclosure experiment in the subtropical China.

Effects of Microcystis blooms on the crustacean plankton were studied using enclosure experiments during July-September, 2000. Eight enclosures were set in the hypereutrophic Donghu Lake. Different nutrient concentrations through additional nutrient and sediment in enclosures were expected to result in different abundance of Microcystis. From July to early August, the phytoplankton community was dominated by Chlorophyta, Cryptophyta, Bacillariophyta and Cyanophyta other than Microcystis aeruginosa. M. aeruginosa showed a rapid increase during early August in all enclosures and predominated. Crustacean plankton was dominated by the herbivorous Moina micrura, Diaphanosoma brachyurum and Ceriodaphnia cornuta, and the predaceous Mesocyclops sp. and Thermocyclops taihokuensis. During the pre-bloom period, the dynamics of M. micrura population appeared to be mainly affected by the predaceous cyclopoids. With the development of Microcystis blooms, such interaction between M. micrura and cyclopoids seemed weakened, especially when the Microcystis biomass was high. But there was no apparent influence on the interaction between Leptodora kindti and its zooplanktonic prey. The density of two cyclopoids decreased with the enhancement of Microcystis. The density decline of M. micrura was caused by both predation and inhibition by Microcystis. The low food availability of other edible phytoplankton during the blooms led to low densities of both C. cornuta and D. brachyurum by late August. It appears that dense Microcystis blooms exert strong negative effects on the herbivorous cladocerans and the predaceous cyclopoids.

Present status and changes of the phytoplankton community after invasion of Neosalanx taihuensis since 1982 in a deep oligotrophic plateau lake, Lake Fuxian in the subtropical China.

Phytoplankton assemblages in the subtrophical oligotrophic Lake Fuxian, the second deepest lake in China, were investigated monthly from September 2002 to August 2003. A total of 113 species belonging to seven phyla were identified, among them, a filamentous green alga, Mougeotia sp., dominated almost throughout the study period and comprised most of the total phytoplankton biomass. Mougeotia sp. has made a substantial development during the past decades: it was absent in 1957, only occasionally present in 1983, increased substantially in 1993, and became predominant in 2002-2003. It is likely that natural invasion of the Taihu Lake noodlefish (Neosalanx taihuensis) has led to a change of dominant herbivorous zooplankton from small to large calanoid, which has increased grazing pressure on small edible algae, and thus has indirectly favored the development of the inedible filamentous Mougeotia sp.