Armoured spiderman: morphological and behavioural adaptations of a specialised araneophagous predator (Araneae: Palpimanidae)

In a predator–prey system where both intervenients come from the same taxon, one can expect a strong selection on behavioural and morphological traits involved in prey capture. For example, in specialised snake-eating snakes, the predator is unaffetced by the venom of the prey. We predicted that similar adaptations should have evolved in spider-eating (araneophagous) spiders. We investigated potential and actual prey of two Palpimanus spiders (P. gibbulus, P. orientalis) to support the prediction that these are araneophagous predators. Specific behavioural adaptations were investigated using a high-speed camera during staged encounters with prey, while morphological adaptations were investigated using electron microscopy. Both Palpimanus species captured a wide assortment of spider species from various guilds but also a few insect species. Analysis of the potential prey suggested that Palpimanus is a retreat-invading predator that actively searches for spiders that hide in a retreat. Behavioural capture adaptations include a slow, stealthy approach to the prey followed by a very fast attack. Morphological capture adaptations include scopulae on forelegs used in grabbing prey body parts, stout forelegs to hold the prey firmly, and an extremely thick cuticle all over the body preventing injury from a counter bite of the prey. Palpimanus overwhelmed prey that was more than 200% larger than itself. In trials with another araneophagous spider, Cyrba algerina (Salticidae), Palpimanus captured C. algerina in more than 90% of cases independent of the size ratio between the spiders. Evidence indicates that both Palpimanus species possesses remarkable adaptations that increase its efficiency in capturing spider prey.     

Winter CO2 Fluxes in Ecosystems of Central Siberia: Comparative Estimates Using Three Different Approaches

Russian Journal of Ecology - Winter CO2 fluxes in Central Siberian ecosystems have been measured using different methodological approaches: dynamic chamber measurements at the soil surface under...     

Landscape connectivity: A conservation application of graph theory

We use focal-species analysis to apply a graph-theoretic approach to landscape connectivity in the Coastal Plain of North Carolina. In doing so we demonstrate the utility of a mathematical graph as an ecological construct with respect to habitat connectivity. Graph theory is a well established mainstay of information technology and is concerned with highly efficient network flow. It employs fast algorithms and compact data structures that are easily adapted to landscape-level focal species analysis. American mink (Mustela vison) and prothonotary warblers (Protonotaria citrea) share the same habitat but have different dispersal capabilities, and therefore provide interesting comparisons on connections in the landscape. We built graphs using GIS coverages to define habitat patches and determined the functional distance between the patches with least-cost path modeling. Using graph operations concerned with edge and node removal we found that the landscape is fundamentally connected for mink and fundamentally unconnected for prothonotary warblers. The advantage of a graph-theoretic approach over other modeling techniques is that it is a heuristic framework which can be applied with very little data and improved from the initial results. We demonstrate the use of graph theory in a metapopulation context, and suggest that graph theory as applied to conservation biology can provide leverage on applications concerned with landscape connectivity.     

Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden

Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.     

Concentration of Organochlorine Pollutants in Surface Waters of the Central European Biosphere Reserve Krivoklatsko (8 pp)

Background, Aim and Scope The article is focused on dioxin, furan, PCB and organochlorine pesticide monitoring in the surface waters of the Central European, protected natural reserve Krivoklatsko, under the UNESCO programme Man and Biosphere. Persistent compounds are presently transported via different means throughout the entire world. This contamination varies significantly between sites. This raises the question of what constitutes the naturally occurring background levels of POPs in natural, unpolluted areas, but which are close to industrialised regions. Information of real background POP contamination can be of high value for risk assessment management of those sites evidently polluted and for the defining of de-contamination limits. Preserved areas should not be seen as isolated regions in which the impacts of human activities and natural factors are either unexpected or overlooked. Every ambient region, even those protected by a law or other means, are still closely connected to neighbouring human developed and impacted areas, and are therefore subject to this anthropogenic contamination. These areas adjacent to natural reserves are sources of diverse substances, via entry of air, water, soil and/or biota. After an extended period of industrial activities, organochlorine pollutants, even those emitted in trace concentrations have reached detectable levels. For future research and for the assessment of environmental changes, present levels of contamination would be of high importance. This work publishes data of the contamination with organochlorine pollutants of this natural region, where biodiversity and ecological functions are of the highest order. Materials and Methods: Semipermeable membrane devices (SPMDs) were utilised as the sampling system. SPMDs were deployed in two small creeks and one water reservoir selected in the central part of the Krivoklatsko Natural Reserve, where it could be expected that any possible contamination by POPs would be lowest. The exposed SPMDs were analysed both for chemical contents of POPs and for toxicity properties. The chemical analyses of dibenzo-dioxins, dibenzo-furans, PCBs and OCPs were analysed by GC/MS/MS on GCQ or PolarisQ (Thermoquest). Toxicity bioassays were performed on the alga Desmodesmus subspicatus, bacteria Vibrio fischeri and crustacean Daphnia magna. All toxicity data were expressed as the effective volume Vtox. Vtox is a toxicity parameter, the determination of which is independent of SPMD deployment time and pre-treatment dilution (unlike, for example, the EC50 of the SPMD extract). Results: The following chemical parameters were monitored: 1) tetra, penta, hexa and hepta dibenzo-p-dioxins and furans; 2) all those detectable from tri- through deca-polychloriated biphenyls (PCBs) and 3) a group of organochlorine pesticides: hexachlorobenzene and isomers of hexachlorocyclohexane, DDE, DDD and DDT. The concentrations of dioxins and furans on the assessed sites varied from under detection levels up to 7 pg.l-1; PCBs were detected in a sum concentration up to 2.8 ng.l-1; and organochlorine pesticides up to 346 pg.l-1. The responses of bioassays used were very low, with the values obtained for Vtox being under 0.03 l/d. Discussion: Toxicity testing showed no toxicity responses, demonstrating that the system used is in coherence with the ecological status of the assessed sites. Values of Vtox were under the critical value – showing no toxicity. The PCA of chemical analysis data and toxicity responses resulted in no correlations between these two groups of parameters. This demonstrated that the present level of contamination has had no direct adverse effects on the biota. Conclusions: The concentration values of six EPA-listed, toxic dioxins and sums of tetra-hepta dioxins; nine EPA toxic dibenzofurans and the sums of tetra-hepta bibenzofurans are presented together with all tri-deka PCBs and organochlorine pesticides (alfa-, beta-, gama-, delta-HCH, HCB, opDDE, ppDDE, opDDD, ppDDD, opDDT, ppDDT). These values represent possible current regional natural background values of these substances monitored within the Central European region, with no recorded adverse effects on the freshwater ecosystem (up until the present time). Recommendations and Perspectives: Assessment of dioxins, furans and other organochlorine compounds within natural reserves can be important for the monitoring of human-induced impacts on preserved areas. No systematic monitoring of these substances in areas not directly affected by industry has generally been realised. There is a paucity of data of the presence of any of these substances within natural regions. Further monitoring of contamination of both soil and biota by dioxins and furans in preserve regions is needed and can be used for future monitoring of man-made activities and/or accidents. Semipermeable membrane devices proved to be a very good sampling system for the monitoring of trace concentrations of ambient organochlorine compounds. Toxicity evaluation using the Vtox concept demonstrated that those localities assessed expressed no toxicity.     

Prenatal and postnatal exposure to diazinon and its effect on spermatogram and pituitary gonadal hormones in male offspring of rats at puberty and adulthood

The objective of this research is to study the possible reproductive adverse effects of diazinon on rat offspring exposed in utero and during lactation. Twenty-four Sprague–Dawley female rats (10–12 week old) were randomly assigned to four groups, each consisting of six rats. Group 1 served as the control and these rats were given normal saline orally. Rats in groups 2, 3, and 4 were administered diazinon, dissolved in saline at 10, 15, 30 mg/ kg^?1 body weight, per oral, once daily, during mating, pregnancy and lactation. The male offsprings were examined at puberty and adulthood for body weight, testis weight, epididymis weight, sperm count, motility and morphology, pituitary-gonadal hormone levels. At 30 mg kg^?1 dose, the male offsprings showed a decrease in testicular weight, sperm count, motility, with an increase in abnormal sperm percentage and a decline in pituitary-gonadal hormones, at puberty. Upon attaining adulthood, there was a decrease in testicular weight, sperm count and motility with an increase in abnormal sperm percentage and a decrease in pituitary hormone level. There was evidence of some adverse reproductive effects on the male offspring at the 15 mg/ kg^?1 dose. Most of the adverse effects were irreversible and were evident at both puberty and adulthood in the offsprings, although a few parameters reverted to the normal growth pattern. Diazinon is a reproductive toxicant for male offsprings if exposed during prenatal and postnatal phases.     

Graph theory as a proxy for spatially explicit population models in conservation planning.

Spatially explicit population models (SEPMs) are often considered the best way to predict and manage species distributions in spatially heterogeneous landscapes. However, they are computationally intensive and require extensive knowledge of species' biology and behavior, limiting their application in many cases. An alternative to SEPMs is graph theory, which has minimal data requirements and efficient algorithms. Although only recently introduced to landscape ecology, graph theory is well suited to ecological applications concerned with connectivity or movement. This paper compares the performance of graph theory to a SEPM in selecting important habitat patches for Wood Thrush (Hylocichla mustelina) conservation. We use both models to identify habitat patches that act as population sources and persistent patches and also use graph theory to identify patches that act as stepping stones for dispersal. Correlations of patch rankings were very high between the two models. In addition, graph theory offers the ability to identify patches that are very important to habitat connectivity and thus long-term population persistence across the landscape. We show that graph theory makes very similar predictions in most cases and in other cases offers insight not available from the SEPM, and we conclude that graph theory is a suitable and possibly preferable alternative to SEPMs for species conservation in heterogeneous landscapes.     

Trampling impact on vegetation of embryonic and stabilised sand dunes in Montenegro

Trampling is one of the human activities that are harmful for plant species and communities of sand dune ecosystems. The aim of this study was to compare the vegetation of embryonic and shifting Ammophila sand dunes with and without fencing to limit trampling. Fenced sand dunes appeared to be richer in species but differences were more prominent in embryonic sand dunes. Some species (Cakile maritima, Pancratium maritimum) were missing on trampled embryonic dunes. The positive impact of trampling exclusion on embryonic sand dunes was indicated by a lowered slope in a Whittaker graph as well as by rarefaction curves that showed higher species richness on the lower slope. Changes in the vegetation of more stabilised shifting Ammophila sand dunes due to trampling are not evident, although species composition is also impoverished. Fencing of parts of sand dunes proved to be an effective measure for vegetation conservation. In addition to physical exclusion of visitors, fences can also have symbolic value for raising public awareness.     

自然保护区、恢复力和动态景观

在这个日益被人类活动所改变的世界里,保护生物多样性对于维持有恢复力的生态系统和确保生态系统产品的可持续流动以及对社会的服务是至关重要的.但是,现有的自然保护区和国家公园不大可能结合生态系统的长期和大尺度的动态.因此,保护策略必须包括大面积的人类利用经营的土地.为了能使生态系统在大规模的自然和人为干扰之后得以重组,以生态存储形式出现的空间恢复力是必备的前提.生态存储包括那些能使生态系统得以重组的物种、相互作用和结构,它的组成部分可能出现在干扰斑块中,也可能出现在周围的景观中.现有的静态自然保护区应该由动态自然保护区加以补充,例如生态休闲地和动态演替保护区,这些都是在景观尺度上模拟自然干扰状况,进行生态系统经营的组成部分.