Structural diversity as a habitat indicator for endangered lakeshore flora using an assemblage of common plant species in Atlantic Canada

Vegetation structure, defined by the height, cover, and types of plants, is an important component of habitat suitability for plant species or communities. The identification of potential habitat is a crucial knowledge gap for endangered Atlantic Coastal Plain Flora (ACPF), a group of taxonomically unrelated plants that share common habitat types and are mostly found on lakeshores and wetlands in the Atlantic coastal region of North America. Our objectives were to assess spatial patterns and relationships of ACPF richness and structural diversity indices at different scales and positions along the lakeshore-to-forest gradient. We sampled 16 sites at 7 lakes in southwestern Nova Scotia using contiguous 20 × 20 cm quadrats along 20 m transects, perpendicular to the waterline, and in 5 × 5 m grids, between the lake and the forest edge. We measured the cover of 19 ACPF species and structural elements at different heights and calculated structural diversity indices using the Shannon index. Spatial patterns were assessed using one- and two-dimensional wavelet variance and covariance. The edge of the zone of high ACPF richness coincided with greater structural diversity at the lakeshore edge. Herbaceous ACPF richness was positively associated with structural diversity at finer scales and on lakeshores, but negatively associated at coarser scales and farther from the waterline. A strong association of structural diversity with ACPF richness suggests it could be used as a habitat indicator for ACPF on lakeshores, which could help the identification and conservation of potential suitable shorelines for ACPF populations in Nova Scotia.     

Influence of biological and ecological factors on hematological values in wild Little Penguins, Eudyptula minor

Clinical hematology and biochemistry are recognized as useful aids in health diagnosis in birds. The Little Penguin (Eudyptula minor) is endemic to Australia and numbers are declining due to a number of factors including declining health. This 2-year study on both Bowen and Lion Island populations aimed at assessing the potential causes of their declining health. Blood was collected from a total of 294 adult Little Penguins. R.B.C., Hb, P.C.V., M.C.V., M.C.H., M.C.H.C., W.B.C. and differential counts, thrombocytes and T.P.P. were measured. Multiple regression was used to identify relationships between hematological values and the following predictor variables: site, season, sex, time held prior to sampling and body condition. Values obtained showed some differences compared to the values for other penguin species reported in the literature. P.C.V., R.B.C., Hb, M.C.H.C. and T.P.P. showed major differences in comparison with a previous study on little penguins. Considering the influence of predictor variables, it appeared that: P.C.V., R.B.C., M.C.V., M.C.H., M.C.H.C. varied according to seasons; P.C.V., R.B.C., M.C.H., T.P.P. were correlated to body condition; P.C.V. was higher in birds on Bowen Island compared to birds on Lion Island; and T.P.P. was higher in females. These ecological and biological predictor variables have a strong influence upon hematological values. As a consequence, they must be taken into consideration when interpreting results of future studies.     

The ecological importance of unregulated tributaries to macroinvertebrate diversity and community composition in a regulated river

Hydrobiologia - In regulated rivers, dams alter longitudinal gradients in flow regimes, geomorphology, water quality and temperature with associated impacts on aquatic biota. Unregulated...     

Species diversity and ecological range in relation to ploidy level in the flora of the Pyrenees

Polyploidy is a major process in plant evolution. Surprisingly, no study has examined its role in species diversification and ecological distribution in relation to other life history traits. In this study, we examine to what extent polyploidy and the other traditionally examined biological traits (pollination mode, dispersal mode and growth form) account for ecological and taxonomic diversity in the flora of the Pyrenees. Fifty genera (in 22 angiosperm families) were classified according to ploidy level, growth form, pollination mode and dispersal mode, and 451 species and/or subspecies in these 50 genera were classified according to ploidy level and growth form. We examined the contribution of ploidy level, pollination and dispersal modes and growth form to (i) the ecological range of species and genera, i.e., the number of natural habitats (defined by a combination of ecological characteristics) where they occur, and (ii) the taxonomic diversity of the 50 genera. Ploidy level and dispersal mode had significant effects on the taxonomic diversity of the 50 genera. Taxonomic diversity, but not polyploidy per se, was significantly correlated with ecological range of genera. For individual species, diploids had a larger ecological range than polyploids, and herbaceous growth forms had wider ecological distributions than other growth forms. Our results indicate that polyploidisation may be a source of ecological diversification of genera, not by increasing the ecological range of particular polyploid species compared to diploids, but rather by creating taxonomic diversity that leads in some genera to a diversification of the habitats occupied by different ploidy levels. This observation is consistent with previous observations of ecological divergence of chromosomal races in some species in the Alps and in the Pyrenees. As found in other studies, species diversification in the studied flora appears to be greatly influenced by the occurrence of multiple dispersal modes, while ecological range of species or subspecies is significantly increased by the presence of herbaceous species.     

Geographical Information Systems in parasitology: a review of potential applications using the example of animal trypanosomosis in West Africa

The epidemiology of vector-borne diseases is complex due to the variability in the ecology of the different actors involved, i.e. hosts, parasites and vectors. The transmission of African animal trypanosomosis in the West-African savannah region is an excellent example of this complexity: riverine tsetse flies have an heterogeneous distribution along the rivers, depending of suitable habitats, and transmit pathogenic trypanosomes were they use domestic animal as feeding hosts. Contrasting epidemiological situations may thus occur at the local scale, and a broad view of the overall environment is necessary to quantify the interfaces in time and space between hosts and vectors. Geographical Information Systems (GIS) can provide new insight into the study of such complex epidemiological processes. GIS is a powerful technology that has been used mainly in map-making, and an enormous amount of knowledge can be gained simply by geographical data projection. GIS also allows juxtaposition of different types of information, creation of new variables, testing of theories and correlation, and generating of predictive models. The purpose of the present paper is to exemplify the potential application of GIS using a recent study carried out on animal trypanosomosis in a cattle-raising area of Burkina Faso.     

Forest proportion as indicator of ecological integrity in streams using Plecoptera as a proxy

An assessment system suitable to support implementation of the EU Water Framework Directive's local water management plans should build on quantitative knowledge about a suite of well-documented indicator and umbrella species’ requirements for different stream orders. Assuring high communication value for improving local public awareness and participation for restoring ecological integrity in impaired headwater streams is critical. Loss and fragmentation of forests are major threats to ecological integrity. The aquatic macroinvertebrate order Plecoptera is commonly used as an indicator of the ecological integrity of streams. We measured abundance and taxonomic richness of Plecoptera in relation to land cover and water chemistry in second and third order catchments’ in 25 headwater streams in Central Europe's Carpathian Mountains. Plecoptera abundance and Plecoptera taxa richness were positively correlated to each other, as well as to forest proportion in the catchments, but negatively correlated to catchment area, inorganic carbon, alkalinity and conductivity. Segmented linear regression was then used to identify thresholds associated to forest proportion as a surrogate for catchment integrity. No threshold was found for Plecoptera abundance, but for taxa richness a threshold of 54% forest cover was found, below which Plecoptera was affected in second order streams. Using Plecoptera as a proxy for ecological integrity this study indicates that forest cover is an effective bioindicator in headwater catchments for predicting the ecological status of headwater streams. The non-linear relationship between forest cover and Plecoptera can be used as a science-based norm whereby land cover monitoring can be used to assess the ecological status of streams.     

Assessment of river health: accounting for perturbation pathways in physical and ecological space

1. A full understanding of changes to river ecosystem structure and functioning along the continuum from relatively pristine to profoundly perturbed requires knowledge of physical, chemical and ecological properties at many spatial and temporal scales. Perturbations may span broad spatio-temporal scales or be spatially and temporally discrete. 2. The relevant scale for study depends on the manner in which perturbations move through two kinds of pathways – through the physical space of the catchment hierarchy and through the ecological space of river food webs. Different kinds of perturbation (e.g. inputs of sediment, nitrogen or phosphorus, changes to shading or discharge) vary in the degree and manner in which they are propagated downstream and through food webs. 3. The fundamental importance of disturbance regimes and refugia to river health is now clear and managers need to take this into account when devising river management schemes. 4. A comparison of the physics, chemistry and ecology of streams in catchments of native tussock and exotic pasture grassland in New Zealand serves to emphasize (i) the extreme complexity of interacting factors resulting from land use change, (ii) the importance of disturbance regime (not encapsulated in biotic indices) and biogeographic patterns (usually unmeasured) in determining ecosystem structure and functioning, and (iii) the lack of concordance between any single index of health and various fundamental features of ecosystem functioning. 5. Practical considerations limit most evaluations of river health to a small suite of indices, though it is important that researchers continue to evaluate the spatial, temporal and biological limitations of these indices. The vagaries of history and geography (extinction and colonization trajectories in relation to natural disturbance regimes) and the complexity of interacting physical, chemical and ecological responses to perturbation suggest that multi-scale, multi-temporal studies of river function offer the best opportunity to evaluate river health.     

Modeling the distribution of Schistosoma mansoni and host snails in Uganda using satellite sensor data and Geographical Information Systems

The potential value of MODIS satellite sensor data on Normalized Difference Vegetation Index (NDVI) and land surface temperatures (LST) for describing the distribution of the Schistosoma mansoni-"Biomphalaria pfeifferi"/Biomphalaria sudanica parasite-snail system in inland Uganda, were tested by developing annual and seasonal composite models, and iteratively analysing for their relationship with parasite and snail distribution. The dry season composite model predicted an endemic area that produced the best fit with the distribution of schools with > or =5% prevalence. NDVI values of 151-174, day temperatures of 26-36 degrees C, and night temperatures of 15-20 degrees C were used as criteria for the prediction model. Using the same approach with host snail data indicated that most of Uganda is suitable "B. pfeifferi"/B. sudanica habitat, except for possibly the north-eastern region of the country. The parasite, however, appears to be restricted in its distribution in both the north-eastern and the south-western regions of Uganda. The absence of disease in the south-west can not be attributed to the absence of snail hosts. Results suggest a combination of satellite sensor data on temperature and standard climate data on precipitation, as the best ecological determinants of the S. mansoni-"B. pfeifferi"/B. sudanica system. Satellite composite models and logistic regression analysis, suggest low night time temperature as one of the significant factors inhibiting S. mansoni transmission in the south-western highland areas of Uganda. The developed models are, however, unique, representing species-specific ecologic preferences of the S. mansoni-"B. Pfeifferi"/B. sudanica system in inland Uganda. Further validation studies are needed to test the value of the model in other countries in East Africa.     

Breakdown of Ficus and Eucalyptus leaves in an organically polluted river in India: fungal diversity and ecological functions

1. At two organically polluted sites in the River Nethravathi, banyan and eucalypt leaves were colonized by one or two species of aquatic hyphomycetes. A total of three or four species were identified at the two sites in samples of water and naturally occurring leaves.
2. Spore production from stream‐exposed leaves by aquatic hyphomycetes was lower by a factor of up to 1 million compared with an earlier study in geographically close but unpolluted streams.
3. Exponential decay rates and loss rates of phosphorus and calcium, were not statistically different from an earlier study in unpolluted streams. Nitrogen increased during decomposition more slowly in the current study.
4. The microbial community on both leaves released enzymes active against starch, pectin, cellulose and xylan.
5. Banyan leaves conditioned for 12 weeks were more palatable to the gastropod Notopala sp. than unconditioned leaves.
6. Together with earlier data from unpolluted streams, the study provides evidence that organic pollution severely restricts diversity of aquatic hyphomycetes and their reproductive output, but does not have an equally strong effect on ecological functions generally associated with this group.     

Assessment of genetic diversity in a Morus germplasm collection using fluorescence-based AFLP markers

To meet various breeding objectives and to conserve the existing genetic resources of mulberry for future use, the present study was undertaken to investigate the amount of genetic diversity and to establish the relationships between mulberry genotypes using fluorescence-based AFLP markers. Genetic diversity was estimated in 45 mulberry accessions from different eco-geographic regions of Japan and other parts of the world. Five primer combinations amplified an average of 110 AFLP markers per primer combination, ranging in size from 35 to 500 bp. A high degree of polymorphism was revealed by these combinations that ranged from 69.7 to 82.3% across all the genotypes studied. Several rare genotype-specific bands were also identified which could be effectively utilized to distinguish different genotypes. The wide range in genetic similarity coefficients (0.58–0.99) indicated that the mulberry germplasm collection represents a genetically diverse popu-lation. The phenetic dendrogram generated by the UPGMA method grouped 45 accessions into four major clusters, which was in agreement with the results from conventional methods. Clustering of some genotypes into strictly separate groups was not readily apparent and no clear interrelationships could be depicted, in spite of their different geographic origin. In addition, AFLP analysis provided sufficient polymorphism for DNA typing and contributed additional insights into the genetic structure of the mulberry germplasm. These results will help in the formulation of appropriate strategies for conservation and variety improvement in mulberry, for which little or no knowledge of genetic diversity is currently available. Received: 30 December 1999 / Accepted: 14 March 2000     

Loss of phytoplankton functional and taxonomic diversity induced by river regulation in a large tropical river

Hydrobiologia - Human activities have disrupted the functioning of river ecosystems around the world. In the Amazon basin, hydropower expansion has affected diversity patterns, but no study has...     

Estimation of the growth rates of epiphytic bacteria and Lemna minor in a river

SUMMARY. Growth of Lemna minor fronds in the River Frome during summer was found to be logarithmic with time and the growth rate (log₁₀) was 0.066 day⁻¹. This is equivalent to a doubling time of 4.5 days. The life expectancy of the fronds was 34 days.
The net change in the density of bacteria epiphytic on the lower surface of Lemna fronds in the R. Frome was monitored using a direct microscopic technique. The observed increase in bacterial numbers has been partitioned into the components of attachment and growth, assuming that attachment occurred at a constant rate and that the bacterial population grew logarithmically. The line which fitted the data best gave an attachment rate of 5.7 × 10⁵ bacteria cm⁻² day⁻¹ and a growth rate (log₁₀) for the bacteria of 0.044 day⁻¹ which is equivalent to a doubling time of 164 h.
Estimates of the rate of detachment of bacteria from Lemna plants were obtained from a laboratory experiment which assumed negligible growth of bacteria in 1 h. The number of bacteria which detached per hour and the sizes of the bacterial populations on the plants before and after detachment were estimated using a plating technique. Different detachment rates were monitored. The detachment rate (analogous to growth rate) which is judged to be most similar to an in situ value was 0.0031 h⁻¹ (0.074 day⁻¹). This rate added to the specific growth rate given above resulted in a corrected growth rate of 0.118 day⁻¹ equivalent to a doubling time of 61 h.     

利用SSR标记与毛细管电泳对甘蔗属进行的遗传分析

为探讨甘蔗属内不同种之间的遗传多样性,利用SSR标记与毛细管电泳技术,对来自甘蔗属3个不同种的12个材料19对引物进行检测,共检测到229个DNA多态性条带,19对引物扩增的DNA条带范围集中在100～260bp之间。12个甘蔗材料的Jaccard遗传相似度,最小0.09,最大0.65,平均为0.26。通过遗传相似性系数分析,UPGMA聚类图内12个甘蔗材料可分为两个群,三个割手密种材料分为一个亚群,甘蔗栽培品种与甘蔗热带种合为一个亚群。结果表明:热带种比割手密种具有和甘蔗栽培品种更亲近的遗传关系;SSR分子标记与毛细管技术结合,相比别的分子标记技术或电泳技术,具有更准确、简便、自动化等优点。     

Impact of arsenic and antimony contamination on benthic invertebrates in a minor Corsican river

The chemical and biological characteristics of a Corsican river that drains contaminated waters and sediment from an abandoned realgar mine were studied. The concentrations of pollutants such as As and Sb were found to be notably high. For example, in the Presa River, downstream the realgar mine, the mean As concentrations in the water and in the sediment were 3010 g 1^-1 and 9450 g g^-1 respectively. Species richness and abundance of benthic invertebrates decreased downstream the As mine. The disappearance of oligochaetes, leeches and a rarity of mayfly populations have been evidenced. On the contrary, a large increase in species belonging to stoneflies and gastropods was found. Some species like Baetis cyrneus, Ephemerella ignita, Sericostoma clypeatum and Ibisia marginata were more sensitive to As and Sb concentrations while others species like Ancylus fluviatilis, Isoperla insularis, Hydropsyche cyrnotica, Caenis luctuosa and Silonella aurata were less sensitive. The benthic invertebrates show different reactions in this contaminated environment, which could be explained by their feeding behaviours and certain morphological characteristics.     

Development and ecological importance of phytoplankton in a large lowland river (River Meuse,Belgium)

The ecological importance of the River Meuse phytoplankton with regard to carbon and nutrient transport has been examined in two reaches of the Belgian course of the river.Field measurements of total particulate organic carbon (POC), particulate organic nitrogen (PON) and particulate phosphorus (PP) show that the large autochtonous production of organic matter strongly affects the carbon and nutrient budget of the aquatic system. During the growing season, phytoplankton accounts for nearly 60% of the POC and dominates the PON. Calculations of the carbon and oxygen budget in the upper reach of the Belgian Meuse demonstrates that the ecosystem is autotrophic, i.e. that autochtonous FPOM (fine particulate organic matter) production is the major carbon input. This suggests that in large lowland rivers, primary production (P) may exceed community respiration (R), i.e. P:R>1, whereas they are assumed to be heterotrophic (P:R<1) in the River Continuum concept.The question of maintenance of phytoplankton in turbid mixed water columns is also addressed, and the case of the River Meuse is treated on the basis of studies of photosynthesis and respiration (ETS measurements). The results suggest that the potamoplankton may show some low-light acclimation, through an increase of chlorophyll a relative to biomass, when it comes to deep downstream reaches, and that algal respiration rate may be reduced. A simulation of the longitudinal development of the algal biomass shows the different phases of algal growth and decline along the river and brings support to the importation hypothesis for explaining maintenance of potamoplankton in the downstream reaches.     

Water management in mediterranean river basins: a comparison of management frameworks, physical impacts, and ecological responses

Rivers in mediterranean climates have been extensively modified by water management infrastructure and practices, yet patterns of development and consequent effects on freshwater ecosystems have not been compared across multiple regions. To evaluate the influence of water management on mediterranean-climate rivers, we compare the historic progression of management policies, institutions, and ecosystem impacts in the Sacramento River (California, USA), Ebro River (Spain), and Biobío River (Chile) basins. There are broad similarities in patterns of ecosystem alterations related to the extensive development of dams and water management infrastructure in the three study basins. Flow regimes have been altered by the reduction of winter peak flows and increased summer baseflows. There are also common patterns of disturbance from sediment transport alteration, water quality degradation, and declines in freshwater biodiversity. Current approaches are inadequate for addressing the formidable water management challenges in California, Spain, and Chile, yet the dramatic evolution of water policies and institutions over the past 150 years suggests that further adaptation is possible. Advances toward integrated and sustainable water management models are likely to occur through incremental change, driven by growing awareness of climate change effects and public demands for water-use efficiency and improved environmental quality.     

Small mammal diet indicates plant diversity,vegetation structure,and ecological integrity in a remote ecosystem

Biodiversity and Conservation - We evaluated patterns of herbivory and predation/scavenging by a small mammal, the arctic ground squirrel (Urocitellus parryii), as an indicator of biological...     

Assessment of ecological diversity of rhizobacterial communities in vermicompost and analysis of their potential to improve plant growth

Present study was designed to determine the microbial diversity from three distinctive sites (amended with vermicompost) of Gujarat, India. A set of 76 strains were screened from total of 438 strains that exhibit plant growthpromoting (PGP) and antagonistic potential isolated from sites PS1 (Mehsana district), BS2 (Dantiwada district) and VS3 (Gandhinagar district). Their diversity indices were studied for determining the species richness and evenness of screened isolates. Results revealed that site BS2 showed the most significant diversity indices in terms of Shannon (H′ 1.525) and Simpson (1/D 5.120) than other two samples. Principal component analysis showed that bacterial diversity (H′) was correlated with the soil characteristics. Chickpea and groundnut plants inoculated with MBCU1 and MBCU3 isolates showed an increase in the vegetative growth parameters that evaluate plant growth when compared to uninoculated controls. Strains MBCU1 and MBCU3 were identified as Pseudomonas stutzeri and Pseudomonas mosselii, respectively, according to sequence analysis of the 16S rRNA gene. These both isolates belong to site BS2 and they showed specific PGP traits suggesting that these isolates can promote plant growth by more than one mechanism with respect to their higher diversity index.     

Microhabitat diversity and associated macroinvertebrates in aquatic banks of a large European river

Microhabitats and associated macroinvertebrate communities in aquatic banks of the Upper Rhône River (upstream from Lyon, France) were studied during the autumn of 1985, under low flow conditions. Based on a regular sampling design (one site every 500 m) along 70 km of riverbank, 18 microhabitat types were identified. Mineral microhabitats (from boulders to clay) accounted for 70%; the remainder corresponded chiefly to the microhabitats of aerial or semi-aerial submerged vegetation (27%) and aquatic vegetation (less than 2%). Using various methods, 239 faunistic samples of microhabitat types resulted in the collection of nearly 64 000 organisms representing 133 taxa. A correspondence analysis showed that most of the 18 microhabitat types were on average well characterized by a specific macrofauna. Microhabitats of aquatic vegetation (hydrophytes and algae) contained the richest fauna in terms of both mean specific richness (15.0 and 13.2 per sample, respectively) and mean density (73 125 and 59 475 ind. m^?2, respectively). By contrast, mineral microhabitats were faunistically poorer (mean specific richness per sample <6.0, except cobbles; and mean density ≤10405 ind. m^?2). The fewest species and lowest density occurred in clay, silt and sand. Estimated mean density of macroinvertebrates in the aquatic banks of the Upper Rhône River was approximately 16 000 ind. m^?2. This was four times higher than in deeper sections of the channel at the same season. The aquatic banks of this large European river, with its great diversity of microhabitats, must be taken into account in all macroinvertebrate studies of fluvial systems.