The ecological status of Lough Corrib,Ireland, as indicated by physiographic factors,water chemistry and macrophytic flora

The submerged flora of selected areas of Lough Corrib was examined in July, 1986. Plant assemblages are described in relation to local geology, topography and water chemistry. The impact of cultural eutrophication on the aquatic flora is discussed. Reference is made to some notable features of the Irish aquatic flora, as exemplified by Lough Corrib.     

竹叶眼子菜种群遗传多样性与群落物种多样性关系的研究

以洪湖中的沉水植物群落及其优势种竹叶眼子菜(Potamogeton wrightii Morong)为研究对象,利用AFLP分子标记结合野外调查的方法,分析保护区(干扰较小)与非保护区(干扰较大,敞水区)中沉水植物群落的物种多样性与竹叶眼子菜遗传多样性之间的相关性。结果显示:洪湖沉水植物群落物种丰富度(S)和物种多样性辛普森指数(D)在保护区和非保护区均未发现显著性差异;竹叶眼子菜的重要值(IV)在保护区(5.2%~23.2%)较非保护区(8.5%~73.3%)稳定。竹叶眼子菜的遗传多样性在两个区未发现显著差异,其遗传多样性与群落物种多样性这两个指标在保护区、非保护区及全湖水平均不相关,说明沉水植物群落的物种多样性和竹叶眼子菜的遗传多样性对不同环境干扰的响应有所差异。     

菹草提取物总黄酮、总酚酸和抗氧化活性含量研究

研究菹草提取物的有效成分,测定其总黄酮含量及总酚酸含量,并确定它的乙酸乙酯和石油醚部位的抗氧化活性成分。采用紫外可见分光光度法,以芦丁和没食子酸作为控制材料,测定菹草的石油醚部位及乙酸乙酯部位中总黄酮和总酚酸含量;采用清除DPPH自由基能力测定法、测定总还原能力铁氰化钾法和水杨酸捕捉羟基自由基法来对菹草各组分提取物的抗氧化能力进行研究。菹草中有一定量的黄酮类化合物和酚酸类化合物存在,不同溶剂提取的部位所含有的总黄酮和总酚酸含量是有差异的,石油醚部位的总黄酮含量要高于乙酸乙酯部位的总黄酮含量,并且总酚酸的含量亦是如此;石油醚部位和乙酸乙酯部位的提取物具有清除DPPH、羟基自由基和还原Fe^3+的能力,各部位清除DPPH、羟基自由基的能力和还原Fe^3+的能力随着样品浓度的增大而增大,且乙酸乙酯部位的测定结果均低于石油醚部位。     

THE ZOOBENTHOS OF THE TOUW RIVER FLOODPLAIN

SUMMARY

An eighteen month study (January 1979 - June 1980) of the sediment, emergent and submerged plant-associated benthic macro-invertebrates of the western sector of the Touw River Flood-plain is reported for four study sites: Wilderness Lagoon, the Touw River and East and West Serpentine. Total invertebrate standing stocks on emergent vegetation were negligible. Those associated with submerged plant communities (essentially Potamogeton pectinatus L.), were generally very much greater than sediment-associated invertebrate standing stocks. The following mean biomasses were recorded for the study period: (a) sediments - Wilderness Lagoon, 19,25; Touw River, 13,06; West Serpentine, 4,37; East Serpentine, 4,68 g dry mass m^?2; (b) - Potamogeton-associated fauna - Touw River, 128,9; West Serpentine, 91; East Serpentine, 35,78 g dry mass m^?2. Of the 37 taxa recorded for Wilderness Lagoon, 33 for Touw River and 31 each for West and East Serpentine sites, the most consistently dominant species were the amphipods, Melita zeylanica Stebbing, Corophium triaenonyx Stebbing, and Grandidierella lignorum Barnard, the tanaid, Apseudes digitalis Brown, and the bivalve mollusc, Musculus virgiliae Barnard. However, suspension feeding Musculus was by far the most important taxon.

In addition to normal winter die-back of Potamogeton, submerged plant cutting activities in the Serpentine lead to an extended period of plant senescence, a prolonged recovery period at the West Serpentine station (between 4–5 months, compared with un-cut Touw River - approximately 2 months), almost complete failure of the plant at East Serpentine, and associated reductions or shifts in the invertebrate community standing stocks, composition and structure. Sediment-associated invertebrate standing stocks at both West and East Serpentine stations increased after Potamogeton harvesting, both immediately and in the long-term. However, these sediment fauna increases nowhere near compensated for the reductions of plant-associated faunal standing stocks due to cutting activities. The significance of these findings is discussed in terms of future management of the area, and comparisons with the situation in Swartvlei, where natural Potamogeton reduction occurred, and with other estuarine and coastal systems, are made.     

Germination and Growth of Potamogeton pectinatus (L.) at Different Water Depths in Lake Nainital,Uttar Pradesh,India

Data on germination of tubers and subsequent growth of young plants of Potamogeton pectinatus were recorded at different depths of the water column in Lake Nainital. The depth of euphotic zone is about 5 m. Tubers were placed at 1, 2.5, 5.0, 7.5 and 10 m water depth in brass net bags. A highly significant negative correlation was found between depth on one hand and germination percentage of tubers, length of shoots and number of leaves on the other hand. Germination of tubers was positively related to pH, dissolved oxygen and temperature of water.     

Lack of detectable isozyme variability in British populations of Potamogeton epihydrus (Potamogetonaceae)

Outside North America Potamogeton epihydrus Raf. is confined to two areas of Britain. An investigation of British material from apparently native sites in the Outer Hebrides and from a canal in northern England (where it is believed to be introduced) revealed only a single isozyme genotype. Ten putative loci were resolved. The IDH phenotype was uniform and three-banded, consistent with heterozygosity (possibly caused by a duplicated locus or preserved by clonal growth). All other enzyme loci were homozygous.