Ecophysiology of Eucalyptus marginata and Corymbia calophylla in decline in an urban parkland

Eucalypt trees are in decline throughout urban landscapes of south western Australia. This study investigated the cause of decline in Eucalyptus marginata and Corymbia calophylla trees in parkland and compared water and nutrient relations with healthy trees in adjacent bushland in Perth, Western Australia. It was hypothesized that: (i) trees were drought stressed through competition for soil water by the vigorous turf; (ii) excessive uptake of nitrogen, because of fertilizer application to turf, caused toxicity; and/or (iii) micronutrient (Cu, Fe, Mn and/or Zn) deficit was induced by high‐pH irrigation water applied to turf around parkland trees. Leaf water potential showed aseasonal variation in the irrigated parkland trees and foliar δ¹³C indicated that parkland trees generally had low water‐use efficiency and were not drought stressed relative to bushland trees. Foliar N levels were not significantly different between parkland and bushland trees indicating that excess N uptake was not a factor in the decline. Foliar total Fe, ‘metabolically active’ Fe, Cu and Zn concentrations were not significantly different between parkland and bushland trees. Foliar manganese concentrations were indicative of deficiency and significantly lower in parkland trees (5–14 µg g^?1) relative to bushland trees (22–35 µg g^?1). It is concluded that application of alkaline irrigation water to the parkland site reduced the plant‐availability of Mn; however, our study of only one parkland site does not allow us to generalize the results across other parklands.     

Microbats in a ‘leafy’ urban landscape: are they persisting,and what factors influence their presence?

Urbanization is an extreme form of habitat modification, but retention of native vegetation in bushland reserves may improve the ecological sustainability of cities. We focused on bats (Microchiroptera) and investigated the use of the urban matrix and surrounding bushland in a region of Sydney, Australia, where remnant bushland persists and gardens often support large trees. Ultrasonic surveys were conducted at 40 sites over one summer season in the backyard matrix, bushland remnants and surrounding National Parks to determine which species were present, and the influence of landscape elements and habitat characteristics on activity, species richness and presence of individual species. In total, 15 of the 17 microbat species known from the Sydney region were recorded in the study area. Yet only three of these species, Chalinolobus gouldii, Mormopterus species 2 and Miniopterus schreibersii were present in more than 40% of sites. Bat activity was significantly higher in remnant bushland on shale soils and in backyards, compared with sandstone gully and ridge remnants, or reference sites in nearby National Parks. Furthermore, species assemblages in urban areas were different from assemblages in reference sites. Of all the habitat characteristics examined, the amount of bushland within 0.5–3 km surrounding a site and tree density were the most common predictors of individual species presence, particularly rare species. Area of bushland, hollow abundance and average tree diameter were positively correlated with species richness, while tree diameter was the strongest predictor of total microbat activity. The proximity of large areas of bushland and the many trees remaining in residential areas of the northern ‘leafy’ suburbs of Sydney allowed the persistence of a range of bat species. The higher bat activity on fertile shale soils indicated that bushland remnants embedded within cities can have high conservation value for bats. Surveys in more urbanized areas of Sydney are needed to test predictions of the models derived in this study.     

天山林区土壤总氮矿化过程对季节性冻融的响应

森林土壤总氮矿化对冻融过程的响应机制尚不明确,氮矿化速率和转化情况尚缺乏定量刻画。通过土壤原位法与室内培养分析相结合,利用~(15)N同位素稀释技术,研究冻融期间天山林区乔木林地、灌丛、草地3种群落类型土壤总氮矿化及转化累积量的动态,分析土壤总氮矿化速率与土壤温度、含水率及微生物量氮(MBN)的相互关系。结果表明:(1)冻融过程及群落类型对总氮矿化速率和MBN含量有极显著的影响(P0.01),秋、春季冻融期的总氮矿化速率相比冻结期更高;(2)季节性冻融期间,乔木林地土壤总氨化累积量在3种群落类型中最高(163.9 kg N hm~(-2) a~(-1)),秋、春冻融期占整个时期的比值约为66%;而总硝化累积量在3种群落类型中相差较小,秋、春冻融期占比均约为77.4%;(3)土壤温度和含水率显著影响总氮矿化速率、净氮矿化速率和MBN速率,随土壤温度增加,总氨化速率(林地和灌丛)显著升高(P0.05);随土壤含水率增加,净氨化速率(灌丛)和净硝化速率(灌丛)显著降低(P0.05)。通过揭示天山林区土壤总氮矿化速率(总氨化速率和总硝化速率)及转化累积量对冻融过程的响应情况,本研究为天山森林土壤中氮的生物地球化学过程提供了有价值的基础数据。     

The urban matrix and artificial light restricts the nightly ranging behaviour of Gould's long‐eared bat (Nyctophilus gouldi)

Cities are heterogeneous landscapes, with remnant vegetation interspersed amongst areas designed for human use. Native wildlife remaining in urban areas are only likely to thrive and persist if they incorporate human altered areas into what they perceive as habitat. Many sensitive species may be lost if they are restricted to remnant vegetation, and cannot use the urban matrix. In this study, we quantify spatial aspects of the ranging behaviour of Gould's long‐eared bat (Nyctophilus gouldi) using radio‐telemetry and acoustic surveys to determine use of the suburban–bushland interface. This species represents a group prone to extinction due to biological attributes that adapt it to flight within cluttered vegetation, making it more specialized. We radio‐tracked 19 individuals in Cumberland State Forest (CSF), a 40‐ha remnant located in north‐west Sydney, New South Wales, Australia. The nightly range (95% Kernel Density Estimator) was small and localized, and was no greater than 80 ha, where individuals moved on average less than 300 m from roosts each night. All individual N. gouldi tracked used bushland in an almost obligate manner, where up to 100% of used habitat was within local bushland, with little to no use of areas classified as ‘urban’ (residential, commercial and educational land uses). Small open spaces exposed to artificial lighting within the main ranging area of CSF had significantly lower activity (bat passes) of Nyctophilus spp. and significantly higher activity of other species more tolerant of urbanization (P < 0.05). Our results demonstrate that artificial lighting can ‘spill‐over’ into bushland and alter the use of preferred habitat. We conclude that large patches (>40 ha) of protected remnant vegetation must be managed to reduce further degradation, and smaller isolated patches could be restored to provide habitat, particularly in narrow bushland corridors, to assist these species to tolerate urban areas.     

Response of native ungulates to drought in semi‐arid Kenyan rangeland

The distribution and abundance of native ungulates were measured on commercially managed, semi‐arid rangeland in central Kenya over a 3‐year period that encompassed severe drought and above‐average rainfall. Native ungulate biomass density averaged 5282 kg km^?2 over the study and was dominated by elephant (Loxodonta africana), impala (Aepyceros melampus) and dik‐dik (Madoqua kirkii). Biomass density of domestic cattle (Bos taurus) averaged 2280 kg km^?2 during the study. Responses of native ungulates to severe drought were variable. Impala densities were similar to or greater than densities for similar habitat in protected areas, and varied from 12 to 16 km^?2 during and following the drought to 24–29 km^?2 following above‐average rainfall. Dik‐dik densities were also greater than densities reported for protected areas and were surprisingly stable throughout the study despite the wide annual fluctuations in rainfall. Elephant migrated out of the region during drought but were present at high densities (2.9–5.2 km^?2) during wet seasons, consistent with telemetry studies emphasizing the importance of Acacia bushland habitat on commercial rangelands for the migratory portion of the Laikipia–Samburu elephant population. Results show that substantial densities of native browsing and mixed‐feeding ungulates can occur on rangeland managed for commercial beef production and suggest that the capacity for ungulates to move over large spatial scales (>100 km²) and to shift distributions in response to locally variable thunderstorms may be important for sustaining these populations.     

Sample Size Effects on Estimates of Population Genetic Structure: Implications for Ecological Restoration

The field of ecological restoration is growing rapidly, and the sourcing of suitable seed is a major issue. Information on the population genetic structure of a species can provide valuable information to aid in defining seed collection zones. For a practical contribution from genetics, a rapid approach to delineating seed collection zones using genetic markers (amplified fragment length polymorphisms [AFLPs]) has been developed. Here, we test the effects of sampling regime on the efficacy of this method. Genetic data were collected for an outcrossing seeder, Daviesia divaricata ssp. divaricata, an important species in urban bushland restoration in Perth, Western Australia. The effect of sample size and number of AFLP markers on estimates of genetic variation and population structure was examined in relation to implications for sourcing material for restoration. Three different sample sizes were used (n= 8, 15, and 30) from six urban bushland remnants. High levels of genetic diversity were observed in D. divaricata (87.4% polymorphic markers), with significant population differentiation detected among sampled populations (Θ^B= 0.1386, p < 0.001). Although sample size does not appear to affect the spatial pattern in principle co‐ordinates analysis (PCA) plots, the number of polymorphic loci increased with sample size and estimates of population subdivision (F_ST and Θ^B) and associated confidence intervals decreased with increasing sample size. We recommend using a minimum of 30 plants for sourcing seed for restoration projects.     

Influence of suburban edges on invasion of Pittosporum undulatum into the bushland of northern Sydney,Australia

Abstract Suburban edges are shown to exert a major influence on invasion of the native Pittosporum undulatum Vent, in dry sclerophyll bushland of northern Sydney. Transect data from fifteen urban bushland sites spanning approximately 90 years of development indicate significant increases of P. undulatum with time. Basal area, density and frequencies of plants in all size-classes increased significantly with age of adjoining development. Mean basal area at edges of old sites was 5700 times greater than in comparable bushland in larger reserve interiors. The effect of age was compounded by the greater impact of edge effects in narrower reserves of older suburbs. Basal areas and proportion of reproductive plants decreased significantly with distance into the reserve. Older sites contained larger but fewer individuals at the edge, compared with high densities of smaller plants further into the reserve, suggesting an advanced successional stage. The overall relationship of density with distance was not significant. The observed clumping of seedlings beneath canopies is consistent with previous work on seed dispersal by vectors, and enhanced seedling recruitment in safe sites. Pittosporum basal area and density reached no maximum levels with age, implying ongoing invasion. The study indicated some factors which appeared to promote the establishment of P. undulatum in the study area. Signs of fire were negatively correlated across all sites with basal area and density of P. undulatum. Human disturbance was positively correlated with the same variables. On the basis of findings in this study, some broad priorities for management of Pittosporum in urban bushland are suggested.     

Regeneration of cleared Acacia zanzibarica bushland in Kenya

Abstract. Woody biomass production in natural forests of arid and semi-arid regions is low. The fuelwood demand of settlements often exceeds the sustained yield and regeneration capacity of natural forests, which results in deforestation. Regeneration and woody biomass development was studied in cleared Acacia zanzibarica bushland in Bura, eastern Kenya. The area was cleared in 1982 and studied in 1988. The site had been colonized primarily by Acacia zanzibarica and A. reficiens. Mean density was 1333 trees/ha, mean total woody biomass (dry weight) 1954 kg/ha, equal to 2.53 m³/ha. Mean annual increment was 293 kg/ha, or 0.3 8m³/ha. Expressed as rain use efficiency, the natural dry matter productivity of the woody component equals 0.83 kg ha^-1 yr^-1 mm^-1. The regeneration potential and some management implications are discussed.     

Amphibian abundance and diversity in Meru National Park, Kenya

The diversity and abundance of amphibians were investigated in Meru National Park, Kenya, using transect sampling, drift‐fence and pitfall trapping and opportunistic collecting. A total of 430 individuals under seven genera (Amietophrynus, Hemisus, Hyperolius, Phrynobatrachus, Phrynomantis, Ptychadena, Xenopus) comprising eleven species were sampled in three different habitats (apart from this, two additional species are known from Meru National Park): Acacia‐wooded grassland; Combretum‐wooded grassland; Acacia–Commiphora bushland. The sex ratio for almost all species was balanced (chi‐square, χ²; P > 0.5) and was not affected by habitat type (ANOVA: F = 8.3026, P = 0.6914). Shannon–Weaver Index (2.227) and Simpson's Index (8.244) were relatively high, and most of the eleven species sampled appeared to have a relatively even distribution (Shannon's Evenness Index, E = 0.927). However, Hemisus marmoratus and Phrynomantis bifasciatus were exclusively recorded in Acacia‐wooded grassland and in low abundances. There was a positive linear relationship of body weight against snout–vent length for two randomly selected anurans (Hyperolius glandicolor, Phrynobatrachus natalensis) among all three vegetation communities.     

Responses of insectivorous bats and nocturnal insects to local changes in street light technology

Artificial light at night is a pervasive anthropogenic stressor for biodiversity. Many fast‐flying insectivorous bat species feed on insects that are attracted to light‐emitting ultraviolet radiation (10–400 nm). Several countries are currently focused on replacing mercury vapour lamps, which emit ultraviolet light, with more cost‐efficient light‐emitting diode (LED) lights, which emit less ultraviolet radiation. This reduction in ultraviolet light may cause declines in insect densities in cities, predatory fast‐flying bats, and some edge‐foraging and slow‐flying bats. Capitalising on a scheme to update streetlights from high ultraviolet mercury vapour to low ultraviolet LED in Sydney, Australia, we measured the activity of individual bat species, the activity of different functional groups and the bat and insect communities, before and after the change in technology. We also surveyed sites with already LED lights, sites with mercury vapour lights and unlit bushland remnants. Species adapted to foraging in cluttered vegetation, and some edge‐space foraging species, were more active in unlit bushland sites than in all lit sites and decreased in activity at lit sites after the change to LED lights. The change to LED streetlights caused a decrease in the fast‐flying Chalinolobus gouldii but not Miniopterus schreibersii oceanensis, the latter being more influenced by seasonal and environmental variables. Insect biomass was not affected by changing light types, but instead was negatively correlated with the moon's percentage illuminance. Changing streetlights to LEDs could result in a decline in some insectivorous bats in cities. This study confirms that unlit urban bushland remnants are important refuges for high bat diversity, particularly for more clutter‐adapted species and some edge‐space foraging species. Preventing light penetration into unlit bushland patches and corridors remains essential to protect the urban bat community.     

Biophysical analysis of afromontane forest community types at Mount Kasigau,Kenya

This study examines how biophysical site conditions differ in relation to the distribution of forest community types at Mount Kasigau, Kenya, in the Eastern Arc. Topographic measures of elevation, slope, curvature and aspect were derived from a 30‐m DEM and temperature and moisture conditions collected from 19 field data loggers for June 2011–2012 measured seasonal change along the steep elevational gradient (1000 m) from bushland to evergreen forest. Nonparametric statistical analyses then compared topographic and climatic conditions among eight ecologically classified forest types. Steep lapse rates in temperature and available moisture support abrupt changes in canopy physiognomy, but dew points declined with elevation. The Kruskal–Wallis test showed significant differences in the elevation, slope, temperature, dew point and relative humidity conditions among the eight forest types. These biophysical conditions are more discrete for Acacia‐Commiphora bushland and cloud forest but not significantly different between riverine forest, lower montane woodlands I and II and Euphorbia quinquecostata woodland, and between semi‐evergreen woodland and evergreen forest. Biophysical conditions and their influence on the distribution of forest types across a heterogeneous mountain landscape are important to understand and monitor in this unpredictably changing tropical seasonal climate.     

Estimation of growth and exopolysaccharide production by two soil cyanobacteria,Scytonema tolypothrichoides and Tolypothrix bouteillei as determined by cultivation in irradiance and temperature crossed gradients

Two filamentous cyanobacteria of the genera Scytonema and Tolypothrix were reported to be effective for stabilizing soil in arid areas due to the production of significant amounts of extracellular polysaccharides (EPS). These EPS may also have applications in the biotechnology industry. Therefore, two cyanobacterial species, Scytonema tolypothrichoides and Tolypothrix bouteillei were examined using crossed gradients of temperature (8–40°C) and irradiance (3–21 W m^?2) to identify their temperature and irradiance optima for maximum biomass and EPS production. According to their reported temperature requirements, both strains were considered mesophilic. The optimum growth range of temperature in S. tolypothrichoides (27 to 34°C) was higher than T. bouteillei (22–32°C). The optimum irradiance range for growth of S. tolypothrichoides (9–13 W m^?2) was slightly lower than T. bouteillei (7–18 W m^?2). Maximum EPS production by S. tolypothrichoides occurred at similar temperatures (28–34°C) as T. bouteillei (27–34°C), both slightly higher than for maximum growth. The optimum irradiance range for EPS production was comparable to that for growth in S. tolypotrichoides (8–13 W m^?2), and slightly lower in T. bouteillei (7–17 W m^?2). The Redundancy Analysis confirmed that temperature was the most important controlling factor and protocols for field applications or for mass cultivation can now be developed.     

Effects of human–livestock–wildlife interactions on habitat in an eastern Kenya rangeland

Human–livestock–wildlife interactions have increased in Kenyan rangelands in recent years, but few attempts have been made to evaluate their impact on the rangeland habitat. This study identified drivers of increased human–livestock–wildlife interactions in the Meru Conservation Area between 1980 and 2000 and their effects on the vegetation community structure. The drivers were habitat fragmentation, decline in pastoral grazing range, loss of wildlife dispersal areas and increase in livestock population density. Agricultural encroachment increased by over 76% in the western zone adjoining Nyambene ranges and the southern Tharaka area, substantially reducing the pastoral grazing range and wildlife dispersal areas. Livestock population increased by 41%, subjecting areas left for pastoral grazing in the northern dispersal area to prolonged heavy grazing that gave woody plant species a competitive edge over herbaceous life‐forms. Consequently, open wooded grassland, which was the dominant vegetation community in 1980, decreased by c. 40% as bushland vegetation increased by 42%. A substantial proportion of agro pastoralists were encountered around Kinna and Rapsu, areas that were predominantly occupied by pastoralists three decades ago, indicating a possible shift in land use in order to spread risks associated with habitat alterations.     

Flow‐injection determination of cysteine in pharmaceuticals based on luminol–persulphate chemiluminescence detection

A flow injection (FI) method is reported for the determination of l‐ cysteine, based on its enhancement on chemiluminescence (CL) emission of luminol oxidized by sodium persulphate in alkaline solution. The calibration graph was linear over the range 1.0 × 10^–9–5.0 × 10^–7 mol/L (r² = 0.9992), with relative standard deviations (RSDs) in the range 1.1–2.3% (n = 4). The limit of detection (3σ blank) was 5.0 × 10^–10 mol/L with a sample throughput of 120/h. The method was applied to pharmaceuticals and the results obtained were in reasonable agreement with the amount labelled. The proposed method was also applied to cysteine in synthetic amino acid mixtures. Calibration graphs of N‐acetylcysteine and glutathione over the range 1.0–50 × 10^–8 and 0.5–7.5 × 10^–7 mol/L were also established (r² = 0.998 and 0.9986) with RSDs in the range 1.0–2.0% (n = 4), and the limits of detection (3σ blank) were 5.0 × 10^–9 and 1.0 × 10^–8 mol/L, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Rapid genetic delineation of local provenance seed‐collection zones for effective rehabilitation of an urban bushland remnant

Abstract The rehabilitation of native plant communities in urban bushland remnants is an increasingly important activity requiring the collection of large amounts of seed. Best practice generally identifies that local seed are best, but how far does the local provenance extend? Using the DNA fingerprinting technique amplified fragment length polymorphism, we assessed genetic differentiation between potential seed source populations and the target population, Bold Park, a large and significant bushland remnant in Perth, Western Australia. For each of 15 species, analysis of molecular variance was used to partition genetic variation within and among populations. Genetic differentiation between Bold Park and potential seed source populations was assessed by non‐metric multidimensional scaling ordination, and statistically by Fisher’s exact tests. The partitioning of variation among populations (Φ_ST) varied from 0.66 for Santalum acuminatum to 0.04 for Mesomelaena pseudostygia. For eight of 15 species, Bold Park plants were completely or largely non‐overlapping with other populations in ordinations, suggesting genetic differentiation and a narrow provenance. Five species showed overlap between Bold Park and some other, but not all, populations sampled, with geographically closest populations generally undifferentiated. Only two species, Acanthocarpus preissii and Mesomeleana pseudostygia, showed little genetic differentiation between Bold Park and all other populations, suggesting a regional genetic provenance. These species can be classified into three broad provenance classes – narrow, local and regional – to help guide decisions about appropriate seed‐collection zones for the rehabilitation of urban bushland remnants.     

The effect of silver and other metal ions on the in vitro growth of root-rotting Phytophthora and other fungal species

A range of metal ions and the oxoanion WO₄^2-were toxic to zoospores of Phytophthora nicotianae parasitica in the order: Ag⁺ > Cu⁺⁺ > WO₄^2-> Ni⁺ > Co⁺⁺ > Zn⁺. The LD₅₀ for Ag⁺, 0.11 μM (11.4 ppb), compared with 1.84 μm (117 ppb) for Cu⁺⁺. Silver was similarly toxic to a range of pathogens including Pythium aphanidermatum, Thielaviopsis basicola and Fusarium oxy-sporum f.spp. Most zoospores of Phytophthora spp. were killed by Ag⁺ in the range 46–460 nM (5–50 ppb), bursting at the higher concentrations. A small sub-population of most propagules exhibited greater tolerance to silver than the whole. In 0.93 μM (100 ppb) Ag⁺ 1.4% of P. nicotianae parasitica zoospores survived but were all killed at 500 ppb. A population of P. cryptogea (1.9%) surviving 0.47 μm (50 ppb) were killed at 0.93 μM (100 ppb). Zoospore cysts and germlings showed the same sensitivity to silver. Oospores were mostly killed over the range 0.23–0.93 μm (25–100 ppb) Ag⁺, some surviving up to the lethal concentration of 9.26 μM (1000 ppb). Mycelium of P. cryptogea was generally less sensitive, with some growth occurring at 9.26 μm (100 ppb). Zoosporangiogenesis was unaffected over the range 0.47–4.65 μm (50–500 ppb). Toxicity increased with increased pH over the range 5.0–6.5. Ionic silver was lost from solution during a microscope slide bioassay by binding to the glass surface. In the presence of chloride ions, colloidal AgCl formed which was equally toxic to P. cryptogea. Silver and AgCl were further lost from solution by colloidal agglomeration - Ostwald ripening - and by AgCl adsorption to glass. Silver, < 90 nM (10 ppb) Ag⁺ as AgNO₃ and particles of silver chloride were both strongly attractive to zoospores of P. cryptogea. Spores burst or failed to germinate on entering lethal concentrations. The results are discussed in the context of the use of silver salts to control Phytophthora root-rot pathogens and the importance of ion availability in in vitro toxicity assays.     

MORPHOLOGICAL CHANGES IN TOXIC AND NON-TOXIC MICROCYSTIS ISOLATES AT DIFFERENT IRRADIANCE LEVELS1

Light intensity (4.5–40.0 μEin m^?2 s^?1) and culture age had a pronounced effect on cell size and size range of a non-toxic axenic Microcystis isolate. The rate of cell volume increase (μm³ d^?1) was 1.03 × light intensity (μEin m^?2 s^?1) – 6.49. Average cell volume varied from 33 to 119 μm³, cells at higher light intensities being larger and having a larger size range. The effects on a toxic axenic Microcystis isolate were similar but less pronounced. Average cell volume ranged from 21–74 μm³. In general, cell size and especially size variability appear to be sensitive indicators of physiological state, with cells under stress conditions being larger and associated with a larger size range. The wide range of cell diameters observed at different irradiance levels (3.4–7.2 μm for the non-toxic and 1.8–6.4 μm for the toxic isolate), makes questionable the use of cell size as a taxonomic character without careful consideration of environmental conditions.     

New species of <Emphasis Type="Italic">Euphorbia</Emphasis> (Euphorbiaceae) from eastern Ethiopia

The new species Solanum pronum Thulin, from Acacia-Commiphora bushland in eastern Ethiopia and central Somalia, is described and illustrated. It is a member of Solanum sect. Somalanum and is compared with S. benadirense, S. jubae and S. pampaninii.     

A comparison of deoxynivalenol intake and urinary deoxynivalenol in UK adults

The relationship between deoxynivalenol (DON) intake and first morning urinary DON was examined in UK adults to validate the latter as a biomarker of human exposure. DON was assessed in first morning samples collected during a period of normal diet, a wheat-restriction intervention diet, and partial wheat-restriction intervention in which bread was allowed. During the partial intervention duplicate bread portions were collected for DON analysis. During the normal diet, partial intervention and full intervention, urinary DON was detected in 198/210 (geometric mean 10.1?ng DON mg^?1 creatinine, 95% confidence interval (CI) 8.6–11.6?ng mg^?1; range nd–70.7?ng mg^?1), in 94/98 (5.9?ng mg^?1, 95% CI 4.8–7.0?ng mg^?1; range nd–28.4?ng mg^?1), and 17/40 (0.5?ng mg^?1, 95% CI 0.3–0.7?ng mg^?1; range nd–3.3?ng mg^?1) volunteers, respectively. A strong correlation between DON intake and the urinary biomarker was observed (p <0.001, adjusted r²?=?0.83) in models adjusting for age, sex and body mass index. These data demonstrate a quantitative correlation between DON exposure and urinary DON, and serve to validate the use of urinary DON as an exposure biomarker.     

Reproductive biology of blue sucker in a large Midwestern river

Efforts to protect or rehabilitate depressed blue sucker Cycleptus elongatus populations require an understanding of life‐history characteristics and reproductive biology to provide fisheries managers with the tools required for science‐based management. The objective of this study was to examine the reproductive biology of blue sucker in the Wabash River, Indiana, during March and April 2006. A total of 105 reproductively mature blue sucker (53 males, 52 females) was collected using boat electrofishing to examine size‐at‐maturity, absolute fecundity, gonadosomatic index (GSI), relative fecundity, and estimated egg size. Size‐at‐maturity was estimated at 515 mm total length (TL) for males and 568 mm TL for females. Mean absolute fecundity of females captured during the study was 150 704 eggs per female (range, 26 829–267 471 eggs per female) and was positively related to both TL (r² = 0.66) and wet weight (r² = 0.77). Mean GSI was 6.4% (range, 2–9.3%) for males and 17.2% (range, 4.3–23.4%) for females. Relative fecundity ranged from 15 331 to 65 887 eggs kg^?1 body weight (mean = 46 946 eggs kg^?1 body weight) and was strongly correlated with GSI (r² = 0.87). Mean estimated egg size was 278 eggs g^?1 (range, 229 364 eggs g^?1) and exhibited an inverse relationship to GSI (r² = 0.42). The results of our study provide information on the reproductive biology of blue sucker which can be used to aid in the identification of potential recovery threats for depressed populations.