Application of photographic capture–recapture modelling to estimate demographic parameters for male Asian elephants

In addition to the threats of habitat loss and degradation, adult males of the Asian elephant Elephas maximus also face greater threats from ivory poaching and conflict with humans. To understand the impact of these threats, conservationists need robust estimates of abundance and vital rates specifically for the adult male segment of elephant populations. By integrating the identification of individual male elephants in a population from distinct morphology and natural markings, with modern capture–recapture (CR) sampling designs, it is possible to estimate various demographic parameters that are otherwise difficult to obtain from this long-lived and wide-ranging megaherbivore. In this study, we developed systematic individual identification protocols and integrated them into CR sampling designs to obtain capture histories and thereby estimate the abundance of adult bull elephants in a globally important population in southern India. We validated these estimates against those obtained from an independent method combining line-transect density estimates with age–sex composition data for elephants. The sampled population was open to gains and losses between sampling occasions. The abundance of adult males in the 176 km² study area was (SÊ ) = 134(14.20) and they comprised 14% (±1%) of the total elephant population. Time-specific abundance estimates for each sampling occasion showed a distinct increase in adult male numbers over the sampling period, explained by seasonal patterns of local migration. CR-based estimates for adult male abundance closely matched estimates from distance-based methods. Thus, while providing abundance data of comparable rigour and precision, photographic CR methods permit estimation of demographic parameters for the Asian elephant that are both urgently needed and difficult to obtain.     

Bird densities are associated with household densities

Increasing housing density is an important component of global land transformation, with major impacts on patterns of biodiversity. However, while there have been many studies of the changes in biodiversity across rural–urban gradients, which are influenced in large part by housing densities, how biodiversity changes across the full range of regional variation in housing density remains poorly understood. Here, we explore these relationships for the richness and abundance of breeding birds across Britain. Total richness, and that of 27 urban indicator species, increased from low to moderate household densities and then declined at greater household densities. The richness of all species increased initially faster with household density than did that of the urban indicator species, but nonurban indicator species richness declined consistently after peaking at a very low housing density. Avian abundance showed a rather different pattern. Total abundance and that summed across all urban indicator species increased over a wide range of household densities, and declined only at the highest household densities. The abundance of individual urban indicator species generally exhibited a hump-shaped relationship with housing density. While there was marked intraspecific variation in the form of such relationships, almost invariably avian abundance declined at housing densities below that at which the UK government requires new developments to be built. Our data highlight the difficulties of maintaining biodiversity while minimising land take for new development. High-density housing developments are associated with declines in many of those species otherwise best able to exploit urban environments, and those components of native biodiversity with which human populations are often most familiar.     

A flow-injection chemiluminescence method for the determination of human serum albumin, using the reaction of fluorescein-human serum albumin-sodium hypochlorite by the enhancement effect of the cationic surfactant cetyltrimethylammonium bromide.

The interaction between surfactant and fluorescein was studied, using a fluorescence spectroscopy and flow-injection (FI) chemiluminescence (CL) method. It was found that the cationic surfactant cetyltrimethylammonium bromide (CTAB) could cause the structural transformation of fluorescein from the quinone to the spirolactone form, and greatly enhance the CL intensity of the fluorescein-human serum albumin (HSA) complex. Based on this finding, a rapid and sensitive FI-CL method was developed for the determination of HSA. Under the optimum conditions, the proposed method has a linear range of 0.05-24.0 microg/mL, with a detection limit of 0.03 microg/mL for HSA (3sigma). The relative standard deviation (RSD) of 1.2 microg/mL HSA (n = 8) is 0.8%. The method was applied to the determination of protein content in urine samples, with satisfactory results. Density functional theory was used to study the mechanism of surfactant-enhanced CL intensity of the fluorescein-HSA complex.     

Multi-scale analysis of responses of stream macrobenthos to forestry activities and environmental context

1. Forestry activities can greatly modify the structure and function of invertebrate communities in streams, but the ability to detect effects of forestry may depend on the spatial scale considered, the choice of response metric and the environmental context. In this study, a multi‐scale, multi‐metric approach was used to compare the usefulness of proximate and larger‐scale measurements of forestry activity for understanding the impacts of forestry on stream macrobenthos. 2. Site‐specific responses of macrobenthic communities to forestry activities measured at four spatial scales (sub‐basin and 8‐, 2‐ and 0.5‐km radii upstream of study sites) were examined for 90 riffle sites distributed among 22 tributary streams (Strahler order 1–5) of the Cascapedia River basin, Quebec, Canada. 3. Multiple regression models and canonical correspondence analysis were used to relate six biological metrics (taxonomic richness, numerical density, biomass density, normalised biomass spectrum, individual body mass and community structure) to variables quantifying logging 1–19 years prior to the study and road density. Environmental predictors (variables quantifying local habitat or landscape features) were included in all analyses to statistically account for environmental context and increase the likelihood of detecting potentially subtle forestry impacts. 4. Forestry activities measured at the larger (sub‐basin and 8 km) scales were linked to decline in taxonomic richness, increase in numerical and biomass densities and shift in size structure of benthic macroinvertebrates, indicating that analyses encompassing larger areas, up to the full basin, may allow for more sensitive detection of effects than those of more limited span. 5. These responses primarily reflected marked increases in the abundance of chironomids and decline in the number of trichopteran taxa with increasing areal coverage of recent (≤2–4 years) cuts, suggesting that larger, longer‐lived and possibly more specialised taxa were more vulnerable to forestry impacts than smaller, multivoltine, generalist invertebrates. After partialling out the influence of other variables, rapid decline in richness occurred even when <1% of the basin had been clear cut in the year prior to the study. 6. Effects of forestry were detected after statistically accounting for natural environmental variability, which may have otherwise concealed those effects. The combined use of multiple biological metrics, partialling out of environmental effects and measurement of impacts at multiple spatial scales may be a broadly applicable approach for enhancing sensitivity and facilitating interpretation in studies of anthropogenic effects on macroinvertebrate communities.     

Spatio-temporal distribution of early life stages of the European anchovy Engraulis encrasicolus L. within a European temperate estuary with regulated freshwater inflow: effects of environmental variables

The spatio-temporal distribution of the anchovy Engraulis encrasicolus in its early life stages was related to environmental conditions within the Guadalquivir River estuary (south-west, Spain) by monthly field surveys during nine periods of recruitment (May 1997 to December 2005). Anchovy post-larvae showed a consistent seasonal pattern of abundance throughout the study period: each year, a high anchovy recruitment period (HARP) occurred from late May to November, with a main peak in July, coinciding with the period when environmental conditions were more stable. Results of stepwise multiple regression analysis indicates that density of its main prey, Mesopodopsis slabberi, explained 45% of total anchovy density variance. Furthermore, after removing the effect of this variable, interannual differences in the anchovy estuarine recruitment were not significant. Clear spatial and tidal trends were also observed for both prey and predator: at each sampling date, density decreased from the outer to inner estuary; at each sampling site, density was higher during ebbs than during floods. Field distributions related to environmental gradients during HARP indicated that the populations of E. encrasicolus and M. slabberi seemed to hold a steady position at a point on the salinity gradient by longitudinal displacement within the estuary. Since freshwater management actions affect the longitudinal position of the salinity gradient as well as the input of nutrients to the estuary and adjacent coastal areas, it is hypothesized that this factor may also be relevant to anchovy recruitment.     

Photosynthesis and Optimal Light Microhabitats for a Rare Cactus, Mammillaria gaumeri, in Two Tropical Ecosystems

Mammillaria gaumeri , an endemic cactus from Yucatan, is threatened due to human-mediated habitat fragmentation but knowledge regarding factors that would inform management plans is limited, including information on optimal microhabitats and growth. We studied seasonal patterns of microclimate, net CO₂ uptake and growth of adult individuals during the dry, rainy and northwind (late fall to winter) seasons in separate populations located in a coastal dune and in a dry forest. To provide an assay of primary productivity, we measured the production of new axillary buds (areoles) from the apex. We found that patterns of net CO₂ uptake in the three seasons were consistent with obligate crassulacean acid metabolism. The reduction in soil water potential and the increase in water vapor pressure deficit led to a reduction in 24-h net CO₂ uptake from 18.0 to 1.3 mmol CO₂/m², after 30 d of drought. Dry-weight gain was maximal during the rainy season and there was no growth during the dry season, thus seasonal patterns of net CO₂ uptake and growth for M. gaumeri reflected soil and atmospheric water contents. Annual dry-weight gain increased linearly with plant size and with total daily photosynthetic photon flux density (PPFD) up to 80 percent of ambient. Maximal growth was in exposed microhabitats receiving 60–80 percent of total ambient PPFD. We hypothesize that low-magnitude disturbances, resulting in more exposed microhabitats, might be beneficial for growth and conservation of adult individuals of this rare species.     

Factors affecting the abundance of introduced hedgehogs (Erinaceus europaeus) to the Hebridean island of South Uist in the absence of natural predators and implications for nesting birds

Introduced hedgehogs Erinaceus europaeus are a known threat to ground-nesting birds on many islands. Spring hedgehog density and sex ratio were measured over a 5-year period at four plots on the 315 km² Hebridean island of South Uist. The mean instantaneous density on the sandy-soiled machair plots (31.8 hedgehogs km⁻², se 2.95) was over twice that on the peaty-soiled blackland plots (15.4 hedgehogs km⁻², se 3.46), a difference reflecting the amount of preferred foraging habitat (mainly pasture). Plot population densities fluctuated approximately in unison. Year-to-year density changes were strongly correlated with temperature in the preceding winter and previous year's spring/summer, indicating that warmer conditions promote both survival and breeding success. The mean spring sex ratio of sub-adults (animals born in the previous calendar year) was not significantly different from 1M:1F. However, the 1.8M:1F ratio observed for adults was significantly male biased, probably a result of female mortality associated with rearing young. The study estimates that in an average year the South Uist hedgehog population numbers c . 2750 (95% confidence limit±800) adults and sub-adults and these produce around 3000 young. Compared with the native range, hedgehog densities on South Uist are shown to be unusually high, probably because their natural predators are absent. High hedgehog densities have led directly to high rates of egg predation of ground-nesting shorebirds and subsequent declines in bird populations. The results suggest that over the past 20 years egg losses have become more severe and control of hedgehogs more difficult because climate warming has resulted in generally more favourable conditions for hedgehogs on the islands.     

The positive correlation between avian species richness and human population density in Britain is not attributable to sampling bias

Aim  To assess whether spatial variation in sampling effort drives positive correlations between human population density and species richness.
Location  British 10 × 10 km squares.
Methods  We calculated three measures of species richness from atlas data of breeding birds in Britain: total species richness, species richness standardised for sampling effort, and the number of species only recorded in supplementary casual records in a manner not standardised for survey effort. We then assessed the form of the relationship between these richness estimates and human population density, both with and without taking spatial autocorrelation into account.
Results  Both total and standardised species richness exhibit similar species richness–human population density relationships; species richness generally increases with human population density, but decreases at the very highest densities. Supplementary species richness is very weakly correlated with human population density.
Main conclusions  In this example, sampling effort only slightly influences the form of species richness–human population density relationships. The positive correlation between species richness and human population density and any resultant conservation conflicts are thus not artefactual patterns generated by confounding human density and sampling effort.     

Habitat and landscape factors associated with neotropical waterbird occurrence and richness in wetland fragments

Habitat destruction alters the structure and spatial arrangement of remnants and creates a novel matrix, affecting the structure of biological communities. This study evaluated the contribution of patch, class and landscape level attributes of 42 wetland fragments and surrounding landscapes on the richness, abundance and presence of waterbird species. Twelve monthly censuses identified 55 species––ranging from 3 to 40 among fragments, and a total of 84,286 birds––ranging from 15 to 19,322. Wetland areas varied from 0.2 ha to 145.2 ha. The presence of 37 out of 42 species could be predicted from the structure of the fragments and the landscapes. The most important predictors were the wetland area (22 models), the rice field matrix permeability (13 models), the microhabitat richness (7 models), the wetland connectivity (5 models), and the wetland isolation (5 models). Discriminant analysis showed that fragments richer in species than expected from their areas, are found in landscapes with greater connectivity and matrix permeability than the species-poor fragments. The total area of rice fields was not related to the richness, abundance or presence of waterbirds in the wetlands fragments. The results suggest that the maintenance of the connectivity among fragments and the matrix permeability through rice-fields could be managed to foster the waterbird conservation at the landscape scale.     

Conformational investigation of alpha,beta-dehydropeptides. XV: N-acetyl-alpha,beta-dehydroamino acid N 'N '-dimethylamides: conformational properties from infrared and theoretical studies.

The FTIR spectra were analysed in the region of the nu(s)(N-H), AI(C=O) and nu(s)(Calpha=Cbeta) bands for a series of Ac-DeltaXaa-NMe2, where DeltaXaa = DeltaAla, (Z)-DeltaAbu, (Z)-DeltaLeu, (Z)-DeltaPhe and DeltaVal, to determine a predominant solution conformation of these alpha,beta-dehydropeptide-related molecules. Measurements were taken in CCl4, DCM and MeCN solutions. In the same way, spectra of saturated analogues Ac-Xaa-NMe2, where Xaa = Ala, Abu, Leu, Phe and Val, were investigated. To help interpret the spectroscopic results, conformational maps were calculated by the B3LYP/6-31+G** method. Also, the relative energies of all conformers of the dehydro compounds in vacuo as well as in the studied solvents in addition to the theoretical IR frequencies of these conformers were calculated. For comparison, molecules of two saturated analogues, Ac-L-Ala-NMe2 and Ac-L-Phe-NMe2, were calculated in a similar way. Both unsaturated and saturated compounds, which have an aliphatic side chain, occur in CCl4 and DCM mainly as a mixture of extended conformers with the C5 H-bond and open conformers. As solvent polarity increases, participation of the open conformers also increases, and in MeCN, the model amides are almost exclusively in the open form, except Ac-DeltaAla-NMe2, which shows a small amount of the H-bonded conformer. Ac-DeltaAla-NMe2 and Ac-DeltaAbu-NMe2 have stronger C5 hydrogen bonds than those of their saturated counterparts. As the calculations indicate, the open conformation of the unsaturated amides is conformer H/F with phi, psi -44 +/- 5 degrees, 127 +/- 4 degrees. This is the second lowest in energy conformer in vacuo and in CCl4 and the lowest one in more polar solvents. The open conformation of Ac-L-Ala-NMe2 constitutes conformer C with phi, psi -101.5 degrees, 112.7 degrees. For Ac-DeltaAla-NMe2 and Ac-DeltaAbu-NMe2, FTIR also reveals the presence of a third conformer. Calculations indicate that is the semiextended conformer D with the N1-H1...N2 hydrogen bond/contact. In all solvents, Ac-L-Phe-NMe2 and Ac-(Z)-DeltaPhe-NMe2 show only the extended E and the open H/F, respectively. In both there is an amide/pi(Ph) interaction.