Freshwater crabs and the biodiversity crisis: Importance, threats, status, and conservation challenges

Freshwater ecosystems in the tropics host a diverse endemic fauna including freshwater crabs, but the rapid loss and deterioration of habitat means that many species are now under imminent threat. Studies on freshwater fish and amphibians suggest a third to half of the species in some tropical freshwaters is either extinct or endangered, but the status of the freshwater crabs is not known. Freshwater crabs, with 1280 species, represent one-fifth of all the World’s brachyurans. We therefore undertook a comprehensive IUCN Red List assessment of the freshwater crabs, which was the first time that such a study had been attempted on a global scale for any group of freshwater invertebrates. The conservation status of all known species from the Americas, Africa, Europe, Asia, and Australasia revealed unexpectedly high threat levels. Here we show that about one-sixth of all freshwater crab species have an elevated risk of extinction, only one-third are not at-risk, and although none are actually extinct, almost half are too poorly known to assess. Out of 122 countries that have populations of freshwater crabs, 43 have species in need of protection. The majority of threatened species are restricted-range semi-terrestrial endemics living in habitats subjected to deforestation, alteration of drainage patterns, and pollution. This is illustrated with a case study of one such species found in Singapore. This underlines the need to prioritize and develop conservation measures before species decline to levels from which they cannot recover. The proportion of freshwater crabs threatened with extinction is equal to that of reef-building corals, and exceeds that of all other groups that have been assessed except for amphibians. These results represent a baseline that can be used to design strategies to save the World’s threatened freshwater crab species.     

Urban drainage systems: An undervalued habitat for aquatic macroinvertebrates

Knowledge about the ecology of urban water systems is very scarce. We assessed the conservation value of urban drainage systems in lowland areas and compared these with similar watercourses in rural areas. A total of 36 water bodies in urban areas were selected to investigate the macroinvertebrate biodiversity in relation to environmental variables. Multivariate analysis of aquatic macroinvertebrate assemblages was used to distinguish urban water types and to link these types to key environmental variables. Several biodiversity indices for urban water systems were compared with those for other drainage systems in The Netherlands. Four types of macroinvertebrate assemblages were distinguished in the urban water systems, differing in environmental conditions and values of ecological indicators. The variation in macroinvertebrate assemblages was significantly explained by nitrate, pH, grain size (sediment composition), transparency, nymphaeid and submerged vegetation. Urban drainage systems can sustain a macroinvertebrate biodiversity comparable to that of drainage systems in rural areas (ditches and canals) and (semi)natural watercourses (lotic waters such as small streams and rivulets) and can even be a habitat for red list species. To optimize biodiversity values, urban water management should aim at lowering nutrient levels, stimulating vegetation (diversity of habitat structure) and increasing transparency, which are key factors for macroinvertebrate diversity. We show the potential conservation benefits of water systems in urban areas, but further studies are needed to investigate the optimal design of cities to include biodiversity as an integrated part of the urban environment, thereby sustaining a higher biodiversity in an increasingly urbanizing world.     

Conservation implications of deforestation across an elevational gradient in the Eastern Arc Mountains, Tanzania

Deforestation is a major threat to the conservation of biodiversity, especially within global centers of endemism for plants and animals. Elevation, the major environmental gradient in mountain regions of the world, produces a rapid turnover of species, where some species may exist only in narrow elevational ranges. We use newly compiled datasets to assess the conservation impact of deforestation on threatened trees across an elevational gradient within the Eastern Arc Mountains of Tanzania. The Eastern Arc has suffered an estimated 80% total loss in historical forest area and has lost 25% of forest area since 1955. Forest loss has not been even across all elevations. The upper montane zone (>1800 m) has lost 52% of its paleoecological forest area, 6% since 1955. Conversely, the submontane habitat (800–1200 m) has lost close to 93% of its paleoecological extent, 57% since 1955. A list of 123 narrowly endemic Tanzanian Eastern Arc tree taxa with defined and restricted elevational ranges was compiled and analyzed in regard to mountain block locations, elevational range, and area of forest within each 100 m elevational band. Half of these taxa have lost more than 90% of paleoecological forest habitat in their elevational range. When elevational range is considered, 98 (80%) of these endemic forest trees should have their level of extinction threat elevated on the IUCN Red List. Conservation efforts in montane hotspots need to consider the extent of habitat changes both within and across elevations and target conservation and restoration efforts throughout these ecosystems’ entire elevational ranges.     

运用气流粉碎机超微粉碎葡萄籽的工艺研究

[目的]探索葡萄籽超微粉碎的最佳工艺。[方法]应用小型气流粉碎机对葡萄籽进行超微粉碎,激光衍射粒度分析仪测定其粒度分布,探索了工质压力、分选频率、进料量、粉碎次数对粉碎效果的影响,并通过正交试验确定最佳工艺。用显微镜观察超微粉的破壁情况。[结果]最佳工艺为:工质压力0.8 MPa,分选频率30 Hz,进料量90 g,粉碎1次。在此条件下得到超微粉的D50(中位径)和D95(累计分布在95%时的粒径)分别为15.61和25.65μm,显微观察发现细胞破壁率在95%以上。[结论]运用气流粉碎机实现了葡萄籽的超微粉碎。     

葡萄花序总RNA提取方法研究

[目的]为筛选出提取葡萄花序总RNA的最佳方法。[方法]以藤稔葡萄花序为试材,针对葡萄花序中多酚、多糖类物质含量较高的特点,比较了CTAB法、SDS／酚法以及经改良的CTAB法对藤稔葡萄花序总RNA的提取效果。[结果]3种方法均能从葡萄花序中提取到总RNA。其中,经改良的CTAB法能有效抑制酚类物质和多糖对总RNA提取的影响,获得纯度高、完整性好的总RNA。其28srRNA亮度约为18SrRNA的2倍,RT—PCR分析表明：该方法提取的总RNA适合于下一步的研究。[结论]经过改良的CTAB法提取葡萄花序总RNA的效果最佳。     

高效液相色谱法测定红甘蓝中矢车菊色素含量

试验建立了红甘蓝提取物中矢车菊色素含量的高效液相色谱测定方法。采用资生堂C18色谱柱(4.6mm×250mm);以甲醇:甲酸水(1:10)=40:60(v/v)作流动相分析矢车菊色素;流速为1.0mL·min-1;柱温为室温;检测波长为530nm。结果表明,红甘蓝提取物中的矢车菊色素含量为0.11‰,平均回收率为104.5%,相对标准偏差(RSD)为0.5%(n=5)。该方法快速、准确、重复性好。     

次氯酸钙处理对红富士苹果防御酶活性的影响

以山东红富士苹果为试材,研究了次氯酸钙浸泡处理(0.15 g/L、0.6 g/L)对其5±1℃贮藏180 d内的防御酶活性的影响。结果表明:供试浓度的次氯酸钙处理在总体上可以抑制PPO活性和提高SOD、CAT、POD活性。低温180 d贮藏期间次氯酸钙0.15 g/L处理的SOD、CAT、POD活性高于0.6 g/L处理,而PPO活性更低,但两者之间没有出现显著差异(p<0.05)。     

丘陵红壤旱地花生套作木薯产量效益分析

田间试验结果表明:丘陵红壤旱地花生套种木薯,对花生的总产量影响不大,无明显差异(p>0.05);空间影响表现为距木薯越近,花生产量越低,负面影响的空间距离为40 cm左右;此外花生木薯间作可明显提高红壤旱地的光能利用率,辅助能转换效率也较花生纯作提高69.42%,产值增加20.3%,纯收入提高24.9%。     

滑菇多糖的制备及体外抗氧化活性作用的研究

超声波辅助提取滑菇多糖,在超声时间为16min、浸提温度为75℃、超声功率700W、料液比为1：30的条件下测得滑菇多糖的得率为9．17％。探讨滑菇多糖的体外抗氧化作用的能力,采用红细胞自氧化溶血、H2O2所致红细胞氧化溶血比色测定。试验得出,滑菇多糖能够明显地在体外抑制人红血细胞自氧化和H2O2所致红细胞氧化溶血作用,对红细胞具有保护作用。     

红壤丘陵区春季黑芝麻品种比较试验

[目的]筛选适宜在江西红壤丘陵地区春季种植的优良黑芝麻品种。[方法]以金黄麻为对照,对中芝9号、08-1、旱芝3号、赣芝5号、ZGBA、金黄麻、青麻、油墩黑、青3-3、赵公鞭10个黑芝麻品种进行了品种比较试验。[结果]中芝9号产量最高,较对照增产457.77kg/hm^2,增产42.47%,08-1、旱芝3号分别比对照增产24.32%和18.34%,赵公鞭产量最低,比对照减产14.90%;08-1单株塑果数最多,为95.6蒴,赵公鞭单株塑果数最少（36.2蒴）;中芝9号每蒴粒数最多（96.2粒）,赵公鞭每蒴粒数最少（44.0粒）;旱芝3号千粒重最重（2.90 g）;中芝9号单株产量最高（11.27 g）。[结论]中芝9号、08-1、旱芝3号、赣芝5号综合性状优良,可代替金黄麻在红壤丘陵区春播种植。