The interplay between local and landscape scales on the density of pond-dwelling anurans in subtropical grasslands

We investigated the role of local and landscape environmental variables on anurans density classified as habitat specialists and generalists in grassland landscapes, known as South Brazilian grasslands (SBG). In this region, we surveyed 187 ponds distributed over 40 landscape sampling units. For each pond, 31 local environmental variables were measured. Each landscape sampling unit was embedded within a larger regional sampling unit with different landscape properties. For each landscape and regional sampling units, 16 landscape metrics were extracted from a land cover and use map. We recorded 35 species, eleven of which are specialists in the SBG. The specialists were affected by 11 local and 2 landscape environmental variables, while generalists were affected by 14 local and one landscape environmental variable. Thus, specialists and generalists presented different relationships with local and landscape variables, but in general local variables had a greater influence on the density of anurans than the landscape variables. However, the landscape indirectly influenced local variables because higher quality ponds were in landscapes with higher percentages of natural habitat. In conclusion, reproductive sites with higher local quality and located within landscapes with higher percentages of natural grasslands are essential to conserve anurans in this habitat. Effective conservation of such sites would benefit from further studies that assess effects of land use and biotic integrity of ponds, which can help to determine (a) the relative effects of local habitat quality of ponds and (b) the effectiveness of protecting ponds and their local surroundings for anuran conservation in SBG. Abstract in Portuguese is available with online material.     

Pioneer marine biofilms on artificial surfaces including antifouling coatings immersed in two contrasting French Mediterranean coast sites

Marine biofilm communities that developed on artificial substrata were investigated using molecular and microscopic approaches. Polystyrene, Teflon® and four antifouling (AF) paints were immersed for 2 weeks at two contrasting sites near Toulon on the French Mediterranean coast (Toulon military harbour and the natural protected area of Porquerolles Island). Biofilms comprising bacteria and diatoms were detected on all the coatings. The population structure as well as the densities of the microorganisms differed in terms of both sites and coatings. Lower fouling densities were observed at Porquerolles Island compared to Toulon harbour. All bacterial communities (analysed by PCR-DGGE) showed related structure, controlled both by the sites and the type of substrata. Pioneer microalgal communities were dominated by the same two diatom species, viz. Licmophora gracilis and Cylindrotheca closterium, at both sites, irrespective of the substrata involved. However, the density of diatoms followed the same trend at both sites with a significant effect of all the AF coatings compared to Teflon and polystyrene.     

Biofouling communities on test panels coated with TBT and TBT-free copper based antifouling paints

Abstract

Formation of biofouling communities on the surfaces of steel panels coated with two different TBT-free copper-based and one TBT-based antifouling paint was examined following submersion for periods of 3, 6, 9 and 12 months in Kastela Bay, Croatia. Test panels coated with Shopprimer and anticorrosive paint were used as control panels. Thirty five taxa of benthic algae and 32 taxa of benthic animals were found. Diatomeae dominated by frequency and abundance on test panels coated with antifouling paints, while the animal species Serpula vermicularis, Mytilus galloprovincialis and Balanus amphitrite amphitrite dominated the fouling communities on control panels. On panels protected by antifouling paints, low values of biomass were found compared to the very high values associated with control panels.     

Short-term succession of marine microbial fouling communities and the identification of primary and secondary colonizers

Microbial succession during the initial stages of marine biofouling has been rarely studied, especially in the Arabian Gulf. This study was undertaken to follow temporal shifts in biofouling communities in order to identify primary and secondary colonizers. Quantitative analysis revealed a significant increase in total biomass, coverage of macrofoulers, chlorophyll a concentrations, and bacterial counts with time. The relative abundance of the adnate diatoms increased with time, whereas it decreased in the case of the plocon diatoms. Non-metric multidimensional scaling (NMDS) ordination based on MiSeq data placed the bacterial communities in three distinct clusters, depending on the time of sampling. While the relative abundance of Alphaproteobacteria and Flavobacteriia decreased with time, suggesting their role as primary colonizers, the relative abundance of Actinobacteria and Planctomycetia increased with time, suggesting their role as secondary colonizers. Biofouling is a dynamic process that involves temporal quantitative and qualitative shifts in the micro- and macrofouling communities.     

Microbial Diversity and Community Structure on Corroding Concretes

The objective of this study was to analyze bacterial diversity in two different concrete samples to understand the dominant types of bacteria that may contribute to concrete corrosion. Two concrete samples, HN-1 from the sunny side and HN-2 from dark and damp side, were collected from Zijin Mountain in Nanjing and genomic DNA was extracted. The partial bacterial 16S rRNA gene fragment was PCR amplified and two clone libraries were constructed. Amplified ribosomal DNA restriction analysis (ARDRA) was performed by digestion of the 16S rRNA gene and each unique restriction fragment polymorphism pattern was designated as an operational taxonomic unit (OTU). Phylogenetic trees of bacterial 16S rDNA nucleotide sequences were constructed. Sample HN-1 and HN-2 contained 21 OTUs and 26 OTUs, respectively. Proteobacteria and Planctomycetes were the predominant bacteria in both samples, and they are distributed among Herbaspirillum, Archangium, Phyllobacteriaceae and Planctomycetaceae. Cyanobacteria and Rubrobacter sp. are dominant in HN-1; while Acidobacteriaceae, Adhaeribacter sp. and Nitrospira sp. are predominant in HN-2. This distribution pattern was consistent with local environmental conditions of these two samples. The inferred physiological characteristics of these bacteria, based on relatedness of the DNA clone sequences to cultivated species, revealed different mechanisms of concrete corrosion depending on the local environmental conditions.     

Blood,War, and Ritual: Religious Ecology, ‘Strong’ Culture,and Human Sacrifice in the Premodern World

What social factors predict human sacrifice in premodern societies? After summarising key insights from competing theoretical perspectives that seek to explain the presence of human sacrifice in premodern societies, we empirically assess the explanatory utility of each theory. We draw from Stark's ‘moral communities’ argument and Alexander and Smith's insights regarding cultural autonomy to highlight how the macro-level organisation of premodern societies impacted the practice of human sacrifice. Using data from Murdock and White's Standard Cross-Cultural Sample, logistic regression models suggest that premodern societies that expressed community ties through religious ceremonies were more likely to engage in human sacrifice, while beliefs in spirit aggression are correlated with lower likelihood of human sacrifice. In terms of non-religious factors, societies that experienced frequent famine were slightly less likely to activity in the ancient world are partly a function of societal complexity. We conclude by specifying the theoretical implications of these findings.     

铬对中国林蛙蝌蚪生长发育的毒性效应

为评价水域环境中铬元素对两栖动物幼体的急性毒性,将中国林蛙(Rana chensinensis)28～29期蝌蚪分别暴露于30～35 mg·L-1Cr(Ⅲ)6个不同浓度和10 ～ 45mg·L-1Cr(Ⅵ)6个不同浓度的水体中,分别在24、48、72和96 h统计蝌蚪的死亡率及半致死浓度(LC50).结果表明:暴露24、48、72和96 h,Cr(Ⅲ)对蝌蚪的LC50分别为34.09±1.06、33.47±0.65、32.58±0.11和(32.05±0.20) mg·L-1,安全浓度(SC)为(3.21±0.02)mg·L-1;Cr(Ⅵ)对蝌蚪的LC50分别为91.97±5.32、51.19±4.62、35.79±1.40和(28.81±1.87) mg·L-1,安全浓度(SC)为(2.88±0.19) rng·L-1.观察表明:Cr(Ⅲ)的急性毒性是通过与蝌蚪皮肤表面的分泌物结合后粘附在鳃部,导致呼吸障碍致死;而Cr(Ⅵ)的强氧化性可导致蝌蚪的表皮溃变,鳃部萎缩致死;另外,将28～29期蝌蚪暴露于安全浓度(SC)以下的含铬水体进行慢性实验,通过检测蝌蚪的体长、体重和完全变态时间显示,低浓度的Cr(Ⅲ)和Cr(Ⅵ)对蝌蚪的生长发育仍具有一定的抑制作用,并可导致畸型发生,其作用强度呈现剂量效应,但时间累积效应不规律.     

濒危鱼类稀有白甲鱼沅江种群与西江种群形态度量学性状的差异性

分别以采自沅江水系142例和西江水系92例稀有白甲鱼标本为材料,采用差异系数法、方差分析法、判别分析法和主成分分析法,研究了稀有白甲鱼沅江种群、西江种群包括10个可数性状和31个比例性状等形态度量学性状的差异性.方差分析表明,2个种群之间共有6个可数性状和27个比例性状存在着显著性差异(P＜0.05).判别分析筛选出了9个对区分2个种群贡献较大的比例性状,并建立了2个种群的判别函数式.主成分分析显示,稀有白甲鱼种群鱼体沿背腹轴、头尾轴分别有16和6个比例性状表现出了明显的变化,在尾部有2个比例性状差异明显.可见2个种群之间形态度量学性状已显示了明显的分化.这可能是两个种群长期隔离,在不同水系生态环境中产生了适应性进化的结果.然而,差异系数的计算结果表明,两个种群之间形态度量学性状的差异尚未达到亚种分化的水平.     

水淹对枫杨幼苗光合生理特征的影响

通过设置对照(CK)、连续性水淹(CF)和间歇性水淹(PF)3个水分处理,模拟三峡库区库岸带土壤水分变化,研究乡土树种枫杨当年实生幼苗的生理生态适应机制.结果表明: 不同水分处理均显著影响枫杨幼苗的光合作用、生物量积累和生长.与CK相比,CF和PF组枫杨幼苗除胞间CO₂浓度升高,净光合速率(P_n)、气孔导度(g_s)均显著降低.其变化趋势是枫杨幼苗的P_n、g_s在试验初期下降,然后逐渐恢复或趋于稳定.随着处理时间的延长,CF和PF组枫杨幼苗的总生物量、根生物量、茎生物量、叶生物量、株高和地径均呈现上升趋势.CF和PF组的总生物量、根生物量、叶生物量和株高,以及PF组的茎生物量均显著低于CK,而CF组的茎生物量与CK无显著差异,其地径还高于CK.枫杨幼苗具有耐受水湿而不耐水淹-干旱交替的生理生态特征.