武汉东湖不同湖区底泥总磷含量及变化的研究

以武汉东湖为对象,研究了1998.03—1999.02期间不同营养水平湖区底泥中(0—5cm,5—10cm)总磷的含量及季节动态。6个站平均总磷含量为1.15mg/g,同80年代初相比,Ⅰ、Ⅱ站底泥中总磷含量分别增高1.42倍和1.03倍。受污水排放影响较重的0站磷含量高达2.78mg/g,而受污水排放影响较小的Ⅳ、Ⅴ站仅分别为0.52mg/g和0.50mg/g。东湖底泥中磷年平均含量与湖水中磷年平均浓度相关系数极高(r=0.997,n=5,p＜0.02)。通过对不同湖泊的底泥磷含量、水柱磷含量和外源负荷的比较和相关分析可以看出,水柱中磷含量较高,磷负荷较大的湖泊底泥中磷含量也高。可以预测,即使东湖的外源负荷得以控制,巨大的底泥磷内源负荷将会继续对东湖水质构成威胁。     

Microsatellite data reveals weak population substructuring in Copadichromis sp.'virginalis kajose', a demersal cichlid from Lake Malawi, Africa

Small but significant differences were found in allele frequencies among five populations (overall F _ST estimate (θ)=0·004, P=0·006; overall R _ST estimate (RHO)=0·019, P <0·00001) of the demersal cichlid Copadichromis sp.'virginalis kajose', collected from five locations in Lake Malawi. Pairwise F _ST estimates revealed significant differences between the most southerly population (Cape Maclear), and the three most northerly populations (Mbamba Bay, Metangula and Chilola). Pairwise R _ST estimates also revealed significant differences between some populations, but no geographical pattern was discernible. There was no evidence of isolation by distance using either the shortest straight-line distance between samples, or the distance around the shoreline following a 50 m depth contour. F _ST estimates were considerably lower than found in previous studies on the mbuna (rock-dwelling species), but higher than those found in a study of three pelagic cichlid species from Lake Malawi. Substructuring in C. sp.'virginalis kajose' appears to be on a similar scale to the Atlantic cod.     

Sperm size of African cichlids in relation to sperm competition

We compared pairs of closely related taxa of cichlid fishesfrom Lake Tanganyika to examine the relationship between spermsize and the presumed intensity of sperm competition. In contrastto previous reports of relatively short sperm in polygamousfishes across a variety of taxa, we found that polygamous cichlidshad significantly longer sperm than their closest monogamousrelatives. In addition, sperm length was significantly relatedto relative testis size (controlling for body size and phylogeny).The site of fertilization may also be correlated with spermlength, as species that fertilize in the female's buccal cavityhad significantly shorter sperm than those that fertilizedeggs on the substrate. Assuming that relatively large testesand polygamous mating are indicative of more intense sperm competition, these results indicate that sperm length is related to the intensityof sperm competition in this clade of cichlids, as has beenfound previously in insects, birds, and mammals.     

A Synoptic Ecopath model of biomass flows during two different static ecological situations in Lake Nakuru (Kenya)

Trophic relationships inside the Lake Nakuru ecosystem during two different phases are described by using the ECOPATH model. This allows a partial explanation of the ecological changes observed in the lake and to show that this apparently unstable ecosystem is characterized by constant transfer efficiencies within the existing trophic levels.     

International study on Artemia LXIII. Field study of the Artemia urmiana (Günther, 1890) population in Lake Urmiah, Iran

Lake Urmiah is a large (total surface 4750–6100 km² in recent times) thalassohaline hypersaline lake (150–180 g l^–1 in the period 1994–1996), located in northwestern Iran. It is the habitat of the endemic Artemia urmiana. Over the period July 1994–January 1996 a sampling campaign was organized: 36 fixed sampling stations, distributed over the entire lake's area, were sampled weekly to determine water temperature, salinity and transparency. At each occasion a filter net was dragged over a distance of 400 m in the superficial water layer to assess the density and composition of the Artemia population. A more limited sampling campaign focused on the annual fluctuations in chlorophyll concentration and on the reproductive behaviour of the brine shrimp population. Several stages of brine shrimp survived during winter months (water temperature 3°C) at low densities. Compared to available data for the Great Salt Lake, USA, Lake Urmiah shows a low algal biomass and overall low Artemia density. The increasing grazing pressure of the developing brine shrimp population in spring seems to prevent the phytoplankton from reaching high blooming concentrations, and oviparity is the dominant reproductive mode throughout the reproductive season.     

Long-term changes of planktonic rotifers in a subtropical Chinese lake dominated by filter-feeding fishes

1. The long-term changes (1956–1998) in density and species composition of planktonic rotifers were studied at two sampling stations (I, II) of Lake Donghu, a shallow eutrophic Chinese Lake densely stocked with filter-feeding fishes. Annual average densities of rotifers increased with an increase in fish yield and eutrophication, whilst species number decreased from 82 in 1962–1963 to 62 in 1994–1998.
2. During 1962–98, some species such as Anuraeopsis fissa , Polyarthra spp. (including P. dolichoptera & P. vulgaris ) , Trichocerca pusilla and Synchaeta oblonga increased their percentage in abundance remarkably, whilst the proportion of Keratella cochlearis decreased at two relatively eutrophic stations from 19 to 4.2% at Station I and from 30 to 3.2% at Station II.
3. The high r _max of A. fissa probably made it more successful than other rotifers under high predation pressure by planktivorous fish. The decrease in the K. cochlearis population might be attributed partly to predation by Cyclops vicinus .
4. Small rotifers were less vulnerable to fish predation than large-sized cladocerans. Decreases in cladocerans coincided with increases in rotifers, suggesting that the indirect effect of fish predation on cladocerans might have partly contributed to the population development of rotifers in Lake Donghu during recent decades.
5. We also conducted surveys (1994–1998) of seasonal dynamics of rotifers at four sampling stations (I–IV) which have varied in trophic status after fragmentation of the lake in the 1960s. A total of 75 species were identified at the four stations. Both densities and biomass of rotifers were considerably higher in the two more eutrophic stations than in the two less eutrophic stations. This indicates that the population increase of rotifers at Stations I and II during recent decades might be partly attributed to eutrophication of the lake water.     

碎石覆盖对河流硬质护坡土壤抗侵蚀性及植物生长的影响

针对河流硬质护坡生态修复中的稳定性和水分平衡等技术难点,提出了一种碎石覆盖技术,并通过抗冲刷实验和盆栽实验分析了不同碎石覆盖对土壤抗冲刷能力、保水性能及植物生长的影响.结果表明：粒径为1.5～2 cm的碎石覆盖处理在增强土壤抗冲刷能力、提高土壤保水性能和植物生物量方面效果明显,但覆盖厚度为5 cm和8 cm的碎石覆盖处理在抗冲刷、保水和促进植物生长方面的作用均无明显差异.厚5 cm、粒径为1.5～2 cm的碎石覆盖技术是硬质护坡生态修复中一种经济有效的技术方法.     

新疆福海底栖动物的研究

本文报道了1985年7月在新疆福海四个湖区的7个断面39个采样点上计采到寡毛类9种,水生昆虫42种,软体动物11种,其它动物7种。在调查湖区中以小海子的种类最多,大海子最少。全湖底栖动物的平均密度为1083个/m2,生物量为18.544g/m2。不同湖区中的现存量有一定差别,密度以中海子为最大,生物量则以“七十三公里”湖区为最高。文中扼要分析了环境条件对底栖动物种类组成和数量分布等方面的影响。       

北京小型湖泊底栖无脊椎动物群落结构特征与营养状况的研究

1987年间逐月调查分析了北京6个小型湖泊底栖无脊椎动物群落结构特征。通过指示种、优势种、种类、数量、生物量、Shannon多样性指数及其与水质的关系分析,前3个湖相当于中营养湖泊,后3个湖相当于中-富营养湖泊。梨形环稜螺(Bellamya purificata)和粗腹摇蚊幼虫(Pelopia sp.)可作为北京6个小湖环境质量的指标生物,前者指示水质较好,后者指示水质较差。Shannon多样性指数值(H′)与湖水BOD、COD、TP、TN含量之间关系比较密切,用该指数并参考指示生物特征评价此类型浅水小湖营养状况是可行的。     

杭州西湖初步治理后的浮游植物现状

本文记录了杭州西湖初步治理后的浮游植物种类组成、相似性、数量分布与环境理化因子的关系,以及根据指示种类评价了西湖水质。在1985年2月至1986年2月周年调查的20个站位中,共鉴定了浮游植物7门92属229种、变种和变型;其中蓝藻门19属39种;绿藻门35属87种8变种1变型;硅藻门24属54种7变种1变型等。西湖浮游植物的数量分布以外湖最高,年均值为529.1×105个/L,三潭内湖最低,仅1.76×105个/L。全湖每升水样含浮游植物细胞密度年均值为614×105个,并且以蓝藻占绝对优势,年均值为423×105个/L,绿藻、硅藻次之,分别为97.3×105个/L和77×105个/L。不同站位浮游植物种类组成的相似性指数值(sorensen 公式)在51.3-85.3范围。