Importance of health assessments for conservation in noncaptive wildlife

Wildlife health assessments help identify populations at risk of starvation, disease, and decline from anthropogenic impacts on natural habitats. We conducted an overview of available health assessment studies in noncaptive vertebrates and devised a framework to strategically integrate health assessments in population monitoring. Using a systematic approach, we performed a thorough assessment of studies examining multiple health parameters of noncaptive vertebrate species from 1982 to 2020 (n = 261 studies). We quantified trends in study design and diagnostic methods across taxa with generalized linear models, bibliometric analyses, and visual representations of study location versus biodiversity hotspots. Only 35% of studies involved international or cross-border collaboration. Countries with both high and threatened biodiversity were greatly underrepresented. Species that were not listed as threatened on the International Union for Conservation of Nature Red List represented 49% of assessed species, a trend likely associated with the regional focus of most studies. We strongly suggest following wildlife health assessment protocols when planning a study and using statistically adequate sample sizes for studies establishing reference ranges. Across all taxa blood analysis (89%), body composition assessments (81%), physical examination (72%), and fecal analyses (24% of studies) were the most common methods. A conceptual framework to improve design and standardize wildlife health assessments includes guidelines on the experimental design, data acquisition and analysis, and species conservation planning and management implications. Integrating a physiological and ecological understanding of species resilience toward threatening processes will enable informed decision making regarding the conservation of threatened species.     

Response of sugar maple to calcium addition to northern hardwood forest

Watershed budget studies at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, have demonstrated high calcium depletion of soil during the 20th century due, in part, to acid deposition. Over the past 25 years, tree growth (especially for sugar maple) has declined on the experimental watersheds at the HBEF. In October 1999, 0.85 Mg Ca/ha was added to Watershed 1 (W1) at the HBEF in the form of wollastonite (CaSiO3), a treatment that, by summer 2002, had raised the pH in the Oie horizon from 3.8 to 5.0 and, in the Oa horizon, from 3.9 to 4.2. We measured the response of sugar maple to the calcium fertilization treatment on W1. Foliar calcium concentration of canopy sugar maples in W1 increased markedly beginning the second year after treatment, and foliar manganese declined in years four and five. By 2005, the crown condition of sugar maple was much healthier in the treated watershed as compared with the untreated reference watershed (W6). Following high seed production in 2000 and 2002, the density of sugar maple seedlings increased significantly on W1 in comparison with W6 in 2001 and 2003. Survivorship of the 2003 cohort through July 2005 was much higher on W1 (36.6%) than W6 (10.2%). In 2003, sugar maple germinants on W1 were approximately 50% larger than those in reference plots, and foliar chlorophyll concentrations were significantly greater (0.27 g/m2 vs. 0.23 g/m2 leaf area). Foliage and fine-root calcium concentrations were roughly twice as high, and manganese concentrations twice as low in the treated than the reference seedlings in 2003 and 2004. Mycorrhizal colonization of seedlings was also much greater in the treated (22.4% of root length) than the reference sites (4.4%). A similar, though less dramatic, difference was observed for mycorrhizal colonization of mature sugar maples (56% vs. 35%). These results reinforce and extend other regional observations that sugar maple decline in the northeastern United States and southern Canada is caused in part by anthropogenic effects on soil calcium status, but the causal interactions among inorganic nutrition, physiological stress, mycorrhizal colonization, and seedling growth and health remain to be established.     

Uptake and toxicity of Cr(III) in celery seedlings

The present study shows that in celery Cr(III) induces deleterious effects on seedling development and morphology, and a number of metabolic responses related to stress. Exogenous CrCl3 from 0.01 to 1 mM increasingly inhibited seed germination and hypocotyl elongation, or completely blocked it (10 mM), while the root apparatus was dramatically damaged even at the lowest dose. Seedlings took up exogenous Cr(III) in a dose-dependent manner, roots being the site of major metal accumulation; translocation towards the hypocotyl and cotyledonary leaves was also detected. Either total or chlorophyll a content was significantly reduced by chromium as low as 0.01 mM. A large accumulation of free and, to a lesser extent, conjugated polyamines occurred in all segments of treated plants. A dose-dependent relationship linking actual amounts of Cr(III) recovered in the entire seedling or organ and the respective polyamine titre was evidenced. Free putrescine, in particular, was the polyamine exhibiting the highest rate of increase, and cotyledonary leaves the organ where the major response occurred. A marked increase in ubiquitin-protein conjugates after Cr(III) treatment was also observed, particularly in roots. Thus, the study suggests for the first time a possible relationship between ubiquitination and Cr(III)-stress. The putative function of polyamines as a stress response, and the recruitment of the ubiquitin pathway to remove damaged or aberrant proteins which might have been produced in metal-treated seedlings are discussed.     

The changing state of contamination in the Lagoon of Venice. Part 2: heavy metals

In order to verify whether pollution is increasing or decreasing, in 25 locations uniformly distributed in the central part of the Lagoon of Venice, a transitional environment suffering from man's urban and industrial activities, the same sampling scheme was repeated three times (in 1987, 1993 and 1998) over a 12-year period during which the lagoonal environment underwent substantial changes. Superficial sediments were sampled and analysed for heavy metals and total organic carbon contents, grain size and density. In general heavy metal contents were found to be correlated, with concentrations above the background level, e.g., for Hg, a concentration factor of 24 was observed in 1987. A temporal decrease in concentrations was observed for most of the metals. Detailed analysis on a smaller spatial scale showed that contamination significantly decreases from the inner border of the lagoon seawards, as highlighted in contour maps. The role of the Porto Marghera industrial zone as a source of pollutants at the border of the Lagoon was confirmed. The decrease in contamination could not be attributed only to a decrease in the intensity of sources, but also to erosion processes, worsened by intensive harvesting of clams with hydraulic dredges.     

Effects of heavy metal exposure on the condition and health of adult great tits (Parus major)

We examined the possible effects of heavy metal exposure on the quality and health of adult great tits (Parus major) at four study sites along a pollution gradient near a non-ferrous smelter in Belgium. Tarsus length, wing length, body mass and condition of great tits were compared with respect to study site, age (first-year and older great tits), sex and season (birds caught in winter and during breeding). Tarsus length did not differ significantly among study sites. The wing length of great tits was larger at the study site furthest from the smelter, especially for older great tits. The length of the outermost tail feathers, however, did not differ significantly among study sites. We found no signs of loss of body mass or condition towards the pollution source. The body mass and condition was lowest for female great tits at the site furthest from the smelter, especially during winter. Haematocrit values did not differ significantly among sites. Overall, we found no clear significant effects of heavy metal pollution on morphological measurements and health parameters of great tits.     

Assessment of Coarse Sediment Mobility in the Black Canyon of the Gunnison River,Colorado

The Gunnison River in the Black Canyon of the Gunnison National Park (BCNP) near Montrose, Colorado is a mixed gravel and bedrock river with ephemeral side tributaries. Flow rates are controlled immediately upstream by a diversion tunnel and three reservoirs. The management of the hydraulic control structures has decreased low-frequency, high-stage flows, which are the dominant geomorphic force in bedrock channel systems. We developed a simple model to estimate the extent of sediment mobilization at a given flow in the BCNP and to evaluate changes in the extent and frequency of sediment mobilization for flow regimes before and after flow regulation in 1966. Our methodology provides a screening process for identifying and prioritizing areas in terms of sediment mobility criteria when more precise systematic field data are unavailable. The model uses the ratio between reach-averaged bed shear stress and critical shear stress to estimate when a particular grain size is mobilized for a given reach. We used aerial photography from 1992, digital elevation models, and field surveys to identify individual reaches and estimate reach-averaged hydraulic geometry. Pebble counts of talus and debris fan deposits were used to estimate regional colluvial grain-size distributions. Our results show that the frequency of flows mobilizing river bank sediment along a majority of the Gunnison River in the BCNP has significantly declined since 1966. The model results correspond well to those obtained from more detailed, site-specific field studies carried out by other investigators. Decreases in the frequency of significant sediment-mobilizing flows were more pronounced for regions within the BCNP where the channel gradient is lower. Implications of these results for management include increased risk of encroachment of vegetation on the active channel and long-term channel narrowing by colluvial deposits. It must be recognized that our methodology represents a screening of regional differences in sediment mobility. More precise estimates of hydraulic and sediment parameters would likely be required for dictating quantitative management objectives within the context of sediment mobility and sensitivity to changes in the flow regime.     

Fetal magnetic resonance imaging (MRI) of ischemic brain injury

The aim of the present study was to demonstrate the usefulness of fetal magnetic resonance imaging (MRI) in ischemic brain injury. We report seven cases of fetal brain ischemia prenatally suspected on ultrasound (US) and confirmed by fetal MRI. Sonographic abnormalities included ventricular dilatation (n=3), microcephaly (n=1), twin pregnancy with in utero death of a twin and suspected cerebral lesion in the surviving co-twin (n=3). MRI was performed with a 1.0 T unit using half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences between 28 and 35 weeks of gestation. US and MRI images were compared with pathologic findings or postnatal imaging. MRI diagnosed hydranencephaly (n=1), porencephaly (n=2), multicystic encephalomalacia (n=2), unilateral capsular ischemia (n=1), corpus callosum and cerebral atrophy (n=1). In comparison with US, visualization of fetal brain anomalies was superior with MRI. The present cases demonstrate that MRI is a valuable complementary means of investigation when a brain pathology is discovered or suspected during prenatal US. Copyright © 2001 John Wiley & Sons, Ltd.     

Chemical analyses of spring waters and factor analysis to monitor the functioning of a karstic system. The role of precipitations regimen and anthropic pressures

An approach is presented to study the functioning of a karstic massif and assess the adverse effects of the anthropogenic pressure by monitoring some water chemical and physical parameters of its main springs. The approach has been applied to the Sette Comuni Plateau (Veneto Region, Italy) hosting a well developed karstic system, whose aquifer presents high vulnerability and undergoes a relevant anthropogenic pressure. The Oliero springs, amongst the largest karstic springs in Europe, are the main water output of the plateau. Electrical conductivity, pH, dissolved O(2), hardness, alkalinity, chemical oxygen demand, total suspended solids, ionic species (NH(4)(+), NO(3)(-), NO(2)(-), PO(4)(3-), SO(4)(2-), Cl(-), F(-)), elements (Cr(III), Cr(VI), Mn, Fe, Ni, Cu, Zn, As, Cd, Hg, Pb), and some chlorinated solvents were monitored for one year. This study presents the application of a factor analysis on the water parameters enabling the identification of the dominant chemical and biological processes and pollution sources affecting the karstic system. Results show four factors which are interpreted as karstification, photosynthesis, storm flow pollution and anions. Finally, by associating metals, chemical oxygen demand and total suspended solids with the amount of rainfall in the 48 h before samplings, further detailed information to the fast response of the aquifer to precipitation events was detected and interpreted according to the factor analysis results. The proposed approach, by providing information on the functioning of the aquifer, may help the management of the karstic plateau and is easily adaptable to similar environments.