New records of water mites of the family Torrenticolidae (Acari, Hydrachnidia) with descriptions of two new species from Nanshih River system in Taiwan and redescription of Torrenticola ussuriensis (Sokolow, 1940) from the Russian Far East

New records of torrenticolid water mites (Acari: Hydrachnidia, Torrenticolidae) from Nanshih River, Taiwan, are presented. Two new species are described: Torrenticola nanshihensis and Torrenticola taiwanicus; the latter species is compared with Torrenticola ussuriensis (Sokolow, 1940), a poorly known species which is re-described based on a new material from the Russian Far East; Monatractides cf. circuloides (Halík, 1930)is reported for the first time for Taiwan.     

Tree community features of two stands of riverine forest under different flooding regimes in Southern Brazil

Two 1 ha plots of a Southern Brazilian subtropical riverine forest, subject to different frequency and duration of floods, were compared to detect the differences in physiognomic structure, tree community composition, richness and diversity. Each plot was made up of 100 contiguous 10×10 m subplots, where 3451 trees with pbh 15 cm were measured and identified. The survey observed 30 tree species, in the frequently flooded plot and 48 in the occasionally flooded plot. A detailed topographical and soil survey was carried out in both plots and indicated that the levels of organic matter and most mineral nutrients were higher in the frequently flooded stand. The forest understory was denser in the occasionally flooded stand which also showed taller emergent trees. Multivariate ordination and grouping techniques showed that the species’ abundance distribution was strongly related to the topographical variation. There was a clear pattern of species turnover according to topographic position, indicating that tree species developed different abilities to survive flooding events. As a result, the two plots also differed in their tree frequency per species regeneration, vertical distribution and dispersion groups. Both species richness and diversity decreased with increasing flood frequency, also showing a patchy distribution within both stands. At a local scale, flooding regime is regulating the spatial variation of α-diversity by forming different seral stages of predictable species composition. Compared to regularly flooded riverine and floodplain forests, riverine forests, with unpredictable flooding regimes, may show higher diversity at a local scale and more abundant opportunistic species of high environmental plasticity.     

Seasonality and controls of phytoplankton productivity in the middle Cape Fear River, USA

Our 1 year study was aimed at assessing seasonal patterns and controls on phytoplankton primary production (PPR) and biomass (chlorophyll a) in a fourth order section of the middle Cape Fear River in North Carolina, USA, and to determine the impact of three low-head lock and dam (LD) structures on these variables within the 70 km study reach of this coastal river. Mean concentrations of NO₃ ⁻–N, NH₄ ⁺–N and soluble reactive phosphorus (SRP) averaged 52.9, 6.0, and 3.6 μmol l⁻¹ in monthly sampling, while the average light attenuation coefficient was 2.4 m⁻¹. The average euphotic depth was 2.1 m. Nutrient concentrations and attenuation coefficients were not significantly different above versus below each LD, or along the entire study reach. Significantly higher concentrations of dissolved O₂ below versus above each LD were attributed to re-aeration during spillway transit. No seasonal pattern in physicochemical properties was apparent. Phytoplankton chlorophyll a concentrations ranged from <1 to 36 μg l⁻¹, while rates of primary production ranged from 18 to 2,580 mg C m⁻² day⁻¹, with values for both variables peaking in the spring and early summer. Chlorophyll a and primary productivity values were consistently higher above versus below each LD in May and June suggesting a seasonal effect, but values were otherwise similar such that overall means were not significantly different. Several factors point to light as the primary control on phytoplankton in the middle Cape Fear River: high nutrient concentrations; a low ratio of euphotic : mixing depth (0.46); progressive increases in chlorophyll a and radiocarbon uptake in all treatments in quarterly nutrient enrichment bioassays conducted at levels of irradiance elevated relative to in situ river values; and consistently low quarterly values of (maximum rate of chlorophyll-normalized C uptake; ≤3.7 mg C mg chl a⁻¹ h⁻¹) and I _k (light saturation parameter; ≤104 μmol photons m⁻² s⁻¹) for photosynthetic light–response (P–I) curves. Handling editor: L. Naselli-Flores     

A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project

Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification.     

Infrared mapping resolves soft tissue preservation in 50 million year-old reptile skin

Non-destructive Fourier Transform InfraRed (FTIR) mapping of Eocene aged fossil reptile skin shows that biological control on the distribution of endogenous organic components within fossilized soft tissue can be resolved. Mapped organic functional units within this approximately 50 Myr old specimen from the Green River Formation (USA) include amide and sulphur compounds. These compounds are most probably derived from the original beta keratin present in the skin because fossil leaf- and other non-skin-derived organic matter from the same geological formation do not show intense amide or thiol absorption bands. Maps and spectra from the fossil are directly comparable to extant reptile skin. Furthermore, infrared results are corroborated by several additional quantitative methods including Synchrotron Rapid Scanning X-Ray Fluorescence (SRS-XRF) and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). All results combine to clearly show that the organic compound inventory of the fossil skin is different from the embedding sedimentary matrix and fossil plant material. A new taphonomic model involving ternary complexation between keratin-derived organic molecules, divalent trace metals and silicate surfaces is presented to explain the survival of the observed compounds. X-ray diffraction shows that suitable minerals for complex formation are present. Previously, this study would only have been possible with major destructive sampling. Non-destructive FTIR imaging methods are thus shown to be a valuable tool for understanding the taphonomy of high-fidelity preservation, and furthermore, may provide insight into the biochemistry of extinct organisms.     

长江三峡库区昆虫丰富度的海拔梯度格局——气候、土地覆盖及采样效应的影响

为了探讨长江三峡库区昆虫丰富度的海拔分布格局以及关键影响因子,针对库区记录的3517种昆虫及其中的害虫,我们整理了这些物种的海拔分布范围数据,分析不同分类学水平、种域宽度等级和分类群的物种丰富度海拔分布模式,采用回归树方法探讨主导的影响因素,并检验相关的假说。结果显示:1)在科、属、种水平,三峡库区分布的昆虫和害虫丰富度均呈随海拔上升先增而后减的格局;狭域、中域和广域种具有显著不同的格局,但三个种域等级的昆虫物种丰富度在海拔1400m以上均显著下降,而害虫丰富度在海拔1200m以上即显著下降。2)对记录昆虫种数>20的科进行TWINSPAN分类,得到物种丰富度海拔格局的4种主要模式;尽管不同程度受采样效应的影响,4种模式均属于单峰格局;3)库区土地利用类型的海拔变化对昆虫、害虫物种丰富度海拔分布具有首要和直接的影响;水热平衡或初级生产力是影响昆虫海拔格局的主导气候因子;而1月均温=0℃可能是限制大多数昆虫物种分布上限的临界温度。上述结果表明,三峡库区的昆虫物种丰富度及其不同组分均具有典型的单峰分布格局,这种格局是人类活动与气候梯度综合作用的结果,但前者的作用更为直接,主要体现在土地利用的海拔梯度变化。这些认识对昆虫多样性资源管理和农林业害虫防治具有参考意义。     

黑河下游额济纳绿洲植物群落物种多样性的空间异质性

采用地统计学方法研究了黑河下游额济纳绿洲物种多样性的空间异质性.结果表明:Margalef丰富度指数(Ma)、Shannon多样性指数(H')、Simpson多样性指数(Ds)和Pielou均匀度指数(J')均服从正态分布,变异系数(CV)为55.8%～67.8%,均属中等变异;Ma和H'符合指数模型,Ds和J'符合球体模型;H'的空间变异程度最高,其次是Ma和J',Ds最小;在变程范围内,各物种多样性指数空间变异的结构性因子占主导地位,所占比例为81.1%～93.0%.各多样性指数沿河流方向的格局变化明显,绿洲核心区达来呼布镇(42°N,101°E)附近为显著高值区,在100°—101°E和102°—102°30'E的带状范围内呈明显的低值区,主要包括东、西戈壁及巴丹吉林沙漠腹地.     

The effects of short term salinity exposure on the sublethal stress response of Vallisneria americana Michx. (Hydrocharitaceae)

Short term exposure of Vallisneria americana to elevated salinity was found to induce a stress response that could be quantified by a series of metabolic assays measuring oxidative stress, photosynthetic efficiency, and dark adapted respiration. Plant specimens exposed to elevated salinity for 24 h displayed signs of oxidative damage represented by the accumulation of reactive oxygen species (ROS) and lipid hydroperoxides in blade tissue (noted at salinities of 10 and 15, respectively). Respiratory demand nearly doubled (140 nanomoles O₂ consumed min⁻¹ g⁻¹) when plants were placed in a salinity of 15 for 24 h versus control specimens maintained at 0. After 1 week of exposure a significant increase in respiration and lipid hydroperoxide content was detected in plants incubated at or above a salinity of 13. In addition, effective quantum yield () dropped significantly compared to plants maintained at a salinity below 13. These results highlight the use of cellular stress assays to monitor salt-induced sublethal responses in V. americana.     

Effects of the freshwater aquarium trade on wild fish populations in differentially‐fished areas of the Peruvian Amazon

Base‐line data were collected to examine the possible effects of the aquarium trade on Amazon fish populations in differentially‐fished locations in the Departmento of Loreto, Peru. Fish abundance, species diversity (richness) and biomass were quantified at three locations with differential fishing pressure, including the Rio Nanay (high pressure), Rio Apayacu and Rio Arambassa (medium) and Rio Yanayacu –Pacaya‐Samiria National Reserve (low). Seining results indicated that the location with the highest fishing pressure had reduced fish abundance, species diversity and biomass compared to the other locations. A similar trend was seen using minnow traps. There was no significant difference in abundance, diversity and biomass between the medium and low fishing pressure locations. Habitat differences (pH and conductivity) among the three locations accounted for <13% of the observed variation, and thus it seemed possible that some of the decline in the Rio Nanay location could be tentatively attributed to increased fishing pressure. Although effects of pollution and habitat alteration could not be ruled out, this is one of the first studies to provide quantitative data on the effect of the freshwater aquarium trade on wild fish populations. While results suggest success in the protection of fishes for the aquarium trade in Pacaya‐Samiria National Reserve, it also may be sustainable to establish limited levels of fishing, as was found in the medium fishing pressure locations, in order to promote economic opportunities and incentives for habitat preservation for indigenous communities.     

Freshwater pollution biomarker: response of brain acetylcholinesterase activity in two fish species

The effect of prolonged exposure at two sites along the Reconquista River (Argentina), a highly polluted peri-urban water body, on brain acetylcholinesterase (AChE, EC 3.1.1.7, acetylcholine acetylhydrolase) of two teleosts was examined. Caged Cyprinus carpio and field-captured Cnesterodon decemmaculatus were used as sentinel organisms. Eserine concentration inhibiting 50% of AChE activity (IC50) and inhibition kinetic parameters were also evaluated. Interspecies IC50 differences were found to agree with observed kinetic parameters (KA, ki and kc), indicating that carps were more sensitive to eserine. Data obtained disclosed spatial differences and demonstrated the high sensitivity of AChE activity as an exposure biomarker. Marked species-related differences were detected, showing that enzyme determination of C. decemmaculatus is more effective in highly polluted sites. Considering the river water physicochemical profile, observed changes in AChE activities can be partly attributed to long-lasting raised concentrations of dissolved heavy metals.