刺参养殖池塘水体中浮游病毒的丰度

运用荧光显微技术,于2007年3～11月,对大连市附近4个地区的刺参养殖池塘及相应的海域进行了浮游病毒丰度的监测和分析,对刺参养殖池塘生态系统的浮游病毒丰度在时间、空间分布上的变化进行了探讨。荧光显微观察结果显示,刺参养殖池塘浮游病毒在时间和空间分布上均存在极显著差异（P〈0.01）,8月中旬平均丰度达到峰值,为2.54×10^10个/L,7月下旬浮游病毒的平均丰度最低,为1.43×10^9个/L。复州湾海域的浮游病毒丰度显著高于其他地区,该地区浮游病毒丰度平均达到1.17×10^10个/L,夏家河子地区浮游病毒丰度最低,平均为3.89×10^9个/L。同一刺参养殖池塘中部区域的浮游病毒丰度高于进水和排水口。刺参养殖池塘水体中浮游病毒丰度与养殖池塘所处的海区位置、养殖池塘的密度密切相关。     

Crustacean and rotifer composition of temporary ponds in the Doñana National Park (SW Spain) during floods

The zooplankton of 18 temporary ponds in the Doñana National Park (SW Spain) was studied during floods in February and May 1997. A total of 37 rotifer taxa and 34 crustaceans species were identified (17 cladocerans, 2 ostracans, 4 diaptomids, 7 cyclopodids, 1 harpacticoid, 1 anostracan, 1 notostracan and 1 conchostracan). Zooplankton samples were collected separately from the littoral and the open-water of 12 different ponds. Commonly distributed zooplankton species (frequency of appearance 50%) were not segregated to either the littoral or the open-water according to a chi-square test (P>0.005). The study ponds were divided into seasonal, intermediate and ephemeral ponds according to the length of their hydroperiod. The total numbers of both crustacean and rotifer taxa were highest in the intermediate-hydroperiod ponds (26 and 32 taxa, respectively). The total number of zooplankton taxa collected in both February and May was not significantly correlated to the hydroperiod of the temporary ponds of Doñana during the study period (r=0.165, P=0.526). 21 rotifer taxa and 20 crustacean species were found in the ephemeral ponds; the number of restricted species was also relatively high (3 rotifers and 4 crustaceans). Therefore, the ephemeral ponds held a relatively rich community during floods compared to other temporary ponds of Doñana despite their small size and short wet phase.     

Carbon and nitrogen dynamics in a small pond in the maritime Antarctic

Small ponds and puddles are extremely common throughout the ice-free areas of the maritime Antarctic. The carbon and nitrogen dynamics in a typical pond on Livingston Island, South Shetland Islands were investigated during summer 1991. The pond vegetation consisted of a benthic mat of cyanobacteria, diatoms and chlorophytes. The mat was not limited by nutrient availability, both phosphorus and nitrogen being available in the overlying water and N:P ratios in both the water and the mat indicating a roughly balanced supply. Maximal rates of carbon fixation of 0.1–0.2 mgC g^–1 dry weight h^–1 were similar to those of other perennial Antarctic mat communities. Productivity appeared to be limited by physical factors, but the effects of irradiance and temperature could not be separated. Although carbon fixation rates were low, carbon loss processes were minimal leading to an accumulation of material in the mat approximating to one doubling per year. Atmospheric nitrogen fixation was not a significant component of the nitrogen budget of the pond, accounting for only 0.1 % of the nitrogen accumulation by the mat. Nitrogen uptake was largely from dissolved nitrogen sources, in particular as dissolved organic nitrogen. It is concluded that ephemeral water bodies may play a significant role in the nutrient dynamics of maritime Antarctic ecosystems.     

Reproductive effort in Daphnia galeata: comparison of reservoir and pond populations

Populations of Daphnia galeata from the deep stratified moderately eutrophic reservoir and the shallow highly eutrophic carp ponds differed in the reproductive effort of the first laboratory generation cultivated at a rich algal diet. The reservoir animals were smaller at the first adult instar and exhibited longer time between hatching of one brood and forming the eggs of the next one.     

Are artificial wetlands good alternatives to natural wetlands for waterbirds? – A case study on Chongming Island, China

Loss of natural wetlands is a global phenomenon that has been a serious threat to the wildlife. A common practice is to construct artificial wetlands to compensate for the loss of natural wetlands. To test whether artificial wetlands as habitats for waterbirds are good alternatives to natural wetlands, we compared species richness, abundance, and seasonal dynamics of waterbird communities of natural (here tidelands) and artificial wetlands (here aquacultural ponds) on Chongming Island, China. Our results indicate that habitat preference of waterbirds showed seasonal difference: most of the shorebirds were found on tidelands in spring, whereas most of the natatorial birds were recorded in aquacultural ponds in winter. Waterbirds preferred the tidelands rather than aquacultural ponds in both spring and autumn, whereas they showed no preference for either the tidelands or the ponds in summer and winter. It is concluded that natural wetlands are better habitats for waterbirds than artificial wetlands on Chongming Island, while the artificial ones are also suitable habitats for waterbirds in winter. The waterbirds might use artificial wetlands only when natural wetlands are unavailable or of poor quality. An over-emphasis that artificial wetlands are suitable habitats for waterbirds might encourage land managers to convert natural wetlands into the artificial ones, resulting in considerable loss of bird diversity. Therefore, for the purpose of bird conservation, it would be a better practice to conserve natural wetlands rather than to construct artificial ones after destruction of natural wetlands.     

Leptospirosis distribution related to freshwater habitats in the Vojvodina region (Republic of Serbia)

The retrospective study (2002—2007) for human leptospirosis in Vojvodina was undertaken in order to describe the distribution of the disease in relation with some environmental factors. Regarding the presented results, the major detected number of leptospirosis cases concurs with stagnant waters, wetlands, fish pond areas and protected regions, which comprised the basis for mapping of the region in three risk zones: very high risk (incidence rate higher than 5.0), high risk (2.5—5.0) and medium risk of leptospirosis infection (1.0—2.5). During the investigated period, 97 cases were registered with an average of 13.85 cases per year: 2002, 32 cases; 2003, 7; 2004, 22; 2005, 16; 2006, 4 and 2007, 16. Out of these 97 cases only 5 were women. Serovars from 11 presumptive serogroups caused infection, with a predominance of Icterohaemorrhagiae and Bratislava, accounting for 72.72% of cases together. Icterohaemorrhagiae was the commonest infecting serogroup mostly connected with fish ponds. Case fatality ratio was 9.4%.     

Missing effects of anthropogenic nutrient deposition on sentinel alpine ecosystems

Anthropogenic nitrogen (N) deposition affects unproductive remote alpine and circumpolar ecosystems, which are often considered sentinels of global change. Human activities and forest fires can also elevate phosphorus (P) deposition, possibly compounding the ecological effects of increased N deposition given the ubiquity of nutrient co‐limitation of primary producers. Low N : P ratios coupled with evidence of NP‐limitation from bioassays led us to hypothesize that P indirectly stimulates phytoplankton by amplifying the direct positive effect of N (i.e. serial N‐limitation) in alpine ponds. We tested the hypothesis using the first replicated N × P enrichment experiment conducted at the whole‐ecosystem level, which involved 12 alpine ponds located in the low N deposition backcountry of the eastern Front Range of the Canadian Rockies. Although applications of N and P elevated ambient N and P concentrations by 2–5×, seston and plankton remained relatively unaffected in the amended ponds. However, additions of ammonium nitrate elevated the δ¹⁵N signals of both primary producers and herbivores (fairy shrimp; Anostraca), attesting to trophic transfer of N deposition to consumers. Further, in situ bioassays revealed that grazing by high ambient densities of fairy shrimp together with potential competition from algae lining the pond bottoms suppressed the otherwise serially N‐limited response by phytoplankton. Our findings highlight how indirect effects of biotic interactions rather the often implicit direct effects of chemical changes can regulate the sensitivities of extreme ecosystems to nutrient deposition.     

Enhancement in the Efficiency of Existing Oxidation Ponds by Using Aquatic Weeds at Little or No Extra Cost—The Macrophyte-Upgraded Oxidation Pond (MUOP)

All over the world, tens of thousands of oxidation ponds are in operation treating sewage and other biodegradable wastewaters. The performance of such ponds can be greatly enhanced if certain aquatic weeds are held in them. The weeds enable better treatment of wastewater in terms of greater reduction in the biochemical oxygen demand (BOD), suspended solids, nitrogen, phosphorous, metals, etc., than is possible in ponds functioning without the weeds. The additional costs of this ‘upgradation’ are minimal compared to the gains, because it essentially involves introduction in the ponds of easily available plants that have no economic value. This paper presents the gist of the know-how utilizable in ‘upgrading’ existing oxidation ponds with the help of aquatic weeds but without any significant additional civil works. It also dwells upon the strategies for the management of the weeds, and their postharvest utilization.     

Zooplankton abundance and diversity in Central Florida grass carp ponds

The effect of the Asian grass carp (Ctenopharyngodon idella Val.) upon the zooplankton in three adjacent experimental ponds (0.139 ha each) was studied for one year. The ponds contained nine species of aquatic macrophytes. Grass carp were stocked into Pond 1 (65 per ha) and Pond 2 (611 per ha) three months after the study was started. At the time of stocking, physichochemical and biological parameters were similar among the ponds.Grass carp did not affect water quality and had little direct or indirect effect upon the zooplankton in the ponds. The abundance and species diversity of zooplankton (number of species, Shannon Index, and Simpson Index) were not significantly different (P < 0.05) between ponds prior to grass carp stocking. After stocking with grass carp, the number of species and species diversity were found to be significantly different (P < 0.05) between Pond 1 (low grass carp stocking rate) and Pond 2 (high grass carp stocking rate). Additionally, significant differences (P < 0.05) in populations between ponds were found for Lecane luna, Monostyla bulla, Lepadella ehrenbergii, Polyarthra sp., and Synchaeta sp. Temporal variation rather than grass carp was probably responsible for those differences. The number of zooplankton per group (Rotifera, Cladocera, and Copepoda) and species diversity were not significantly different (P<0.05) between ponds containing different stocking rates of grass carp.During the study, zooplankton were collected with a shallow-water sampler. No significant differences (P < 0.05) between collections were found for the sampler and a No. 20 mesh nylon zooplankton net.