Inferring Threat from Scientific Collections

Exact formulas for the probability of extinction or change in the conservation status of species are described for data based on frequency of sighting. These formulas generalize an expression previously described for the probability of extinction from (binary) sighting data. The formulas will be used in contexts where sightings are recorded as frequencies, such as when observations are aggregated in time. We argue that computing the probability of extinction or change in conservation status will be most useful for setting conservation priorities and in screening large data sets contained in museum and herbarium collections and in biological resource inventories.     

Heterogeneity of chlorinated hydrocarbon sorption properties in a sandy aquifer

Hydraulic conductivity and sorption coefficients for chlorinated hydrocarbons (chloroform, carbon tetrachloride and tetrachloroethylene) were evaluated for 216 sediment samples collected across a 15 m transect and a 21 m depth interval in a contaminated aquifer near Schoolcraft, Michigan. Relationships between hydraulic conductivity, linear sorption partition coefficients, grain size classes, and spatial location were investigated using linear regression analysis and geostatistical techniques. Clear evidence of layering was found in sorption properties, hydraulic conductivity and grain sizes. Conductivity correlated well with grain size, as expected, but sorption varied inversely with grain size, contrary to some previous reports. No significant correlation was found between sorption properties and hydraulic conductivity. This is likely due to the unexpected presence of small amounts of highly sorptive coal-like solids, which dominate the sorption behavior but have little effect on conductivity. The results demonstrate that recent findings regarding the high sorption capacity of coal materials found in soils can exert a controlling influence on contaminant transport. Designers of in situ remediation systems should be cautioned that 1) it is not reasonable to assume that sorption capacity and hydraulic conductivity are related, 2) sorption capacity and hydraulic conductivity are critical measurements for contaminant site characterization and subsequent transport modeling, 3) estimating sorption capacity from organic carbon measurement may lead to greater errors than performing sorption isotherms, and 4) it is more important to characterize vertical heterogeneity rather than horizontal heterogeneity because both sorption and hydraulic conductivity are correlated across longer distances in the horizontal plane.     

Road development, housing growth, and landscape fragmentation in northern Wisconsin: 1937-1999.

Roads remove habitat, alter adjacent areas, and interrupt and redirect ecological flows. They subdivide wildlife populations, foster invasive species spread, change the hydrologic network, and increase human use of adjacent areas. At broad scales, these impacts cumulate and define landscape patterns. The goal of this study was to improve our understanding of the dynamics of road networks over time, and their effects on landscape patterns, and identify significant relationships between road changes and other land-use changes. We mapped roads from aerial photographs from five dates between 1937 and 1999 in 17 townships in predominantly forested landscapes in northern Wisconsin, U.S.A. Patch-level landscape metrics were calculated on terrestrial area outside of a 15-m road-effect zone. We used generalized least-squares regression models to relate changes in road density and landscape pattern to concurrent changes in housing density. Rates of change and relationships were compared among three ecological regions. Our results showed substantial increases in both road density and landscape fragmentation during the study period. Road density more than doubled, and median, mean, and largest patch size were reduced by a factor of four, while patch shape became more regular. Increases in road density varied significantly among ecological subsections and were positively related to increases in housing density. Fragmentation was largely driven by increases in road density, but housing density had a significantly positive relationship with largest patch area and patch shape. Without protection of roadless areas, our results suggest road development is likely to continue in the future, even in areas where road construction is constrained by the physical environment. Recognizing the dynamic nature of road networks is important for understanding and predicting their ecological impacts over time and understanding where other types of development are likely to occur in the future. Historical perspectives of development can provide guidance in prioritizing management efforts to defragment landscapes and mitigate the ecological impacts of past road development.     

Steady Shallow-Water Current and Solute Transport around a Semi-Conical Headland

Laboratory experiments have been carried out to investigate the effects of a sloping wall headland on the flow characteristics and the associated concentration distributions from a point source around the headland. A semi-conical headland with a slope of 1:2 was set up in a flow basin, 4.8 m long and 3.8 m wide. In this paper, the experimental results of a steady shallow-water current are reported. Three dimensional flow velocities in the basin were measured using Sontek-ADV instrument. The dye concentration levels in the basin were measured by two fluorometers. The experimental results showed a large-scale re-circulation region behind the semi-conical headland. The peak turbulence energy, at about 53% of the local kinetic flow energy, coincides with the region of high velocity gradient. Significant vertical flows were observed around the area near the downhill slope of the headland, with a maximum ratio of vertical to horizontal velocities being about 22%. Such relatively significant vertical scouring velocities, coupled with strong turbulence energy and high horizontal velocity gradients in the same region, could cause severe bed erosion. The experimental results have also been compared with the predicted results of a depth-averaged numerical model. The predicted eddy structure and the concentration distribution in the re-circulation area were found to compare favourably with the experimental results. However, the discrepancies in the flow velocities and the concentration levels near the headland were apparent. It was observed that the dye concentration continued to spread in the cross-stream direction after passing the headland, whereas only a limited extent of the lateral spreading was predicted by the numerical model further downstream of the headland.     

Blue-winged warblers (Vermivora pinus) “recognize” dialects in type II but not type I songs

Summary Male blue-winged warblers (Vermivora pinus) sing two distinctly different song types (I and II). Type II songs from eastern New York and western Massachusetts, USA, are different (Fig. 1), and during playback experiments males respond stronger to local than to foreign songs (Fig. 2). Type I songs are more stereotyped geographically (Fig. 1), and males do not differentiate between local and foreign Type I songs (Fig. 3). Differing degrees of intra- and inter-sexual selection on these two forms may have promoted variability in Type II songs and stereotypy in Type I songs among locations.     

Influence of insect hormones on the establishment of dominance hierarchies among foundresses of the paper wasp,Polistes gallicus

Summary Laboratory studies on overwintered foundresses of Polistes gallicus show that differences in the endocrine activity are mainly responsible for achieving the dominance rank. Females that became dominant had either larger corpora allata or more developed ovaries than subordinate females. Body size did not contribute to dominance rank. Since a correlation exists between the length of terminal oocytes and the ecdysteroid titre in haemolymph as well as between the volume of corpora allata and the synthesis of juvenile hormone, dominant behaviour is thought to depend upon an elevated hormone titre in haemolymph. Injections of juvenile hormone (JHI) and 20-hydroxyecdysone, separately and simultaneously, significantly increased the probability that the treated female would be the dominant female of a test pair. After a hierarchy has been established, endocrine activity in subordinate foundresses is inhibited by the dominant foundress that then monopolizes reproduction.     

Comparative vulnerability to predators,and induced defense responses,of eastern oysters Crassostrea virginica and non-native Crassostrea ariakensis oysters in Chesapeake Bay

Management agencies are considering introducing the Suminoe oyster Crassostrea ariakensis into Chesapeake Bay, USA. It is unknown if the growth of feral populations of this non-native oyster would be regulated by the same predators that once controlled the abundance of the native eastern oyster C. virginica. In laboratory studies, we compared the relative susceptibility of juvenile diploids (shell height < 25 mm) of both oyster species to invertebrate predators of eastern oyster juveniles. Predators included four species of mud crabs [Rhithropanopeus harrisii (carapace width 7–11 mm), Eurypanopeus depressus (6–21 mm), Dyspanopeus sayi (8–20 mm), and Panopeus herbstii (9–29 mm)], the blue crab Callinectes sapidus (35–65 mm), and two sizes of polyclad flatworms (Stylochus ellipticus and possibly Euplana gracilis; planar area ≲5 mm² and ∼14 to 88 mm²). All four species of mud crab and the blue crab preyed significantly (ANOVA, P ≤ 0.05) more on C. ariakensis than on C. virginica, but predation by flatworms of both sizes did not differ significantly between oyster species. The greater susceptibility of C. ariakensis to crab predation was likely due to its shell compression strength being 64% lower than that of C. virginica (P = 0.005). To test for predator-induced enhancement of shell strength, we held oysters of both species for 54 days in the presence of, but protected from, C. sapidus and R. harrisii. Crabs were fed congeneric oysters twice weekly within each aquarium. Compared to controls, shell strength of C. virginica exposed to R. harrisii increased significantly (P < 0.043), as did shell strength of both oyster species exposed to C. sapidus (P < 0.01). Despite the changes in shell strength by both oyster species in the presence of C. sapidus, the shell of C. ariakensis remained 57% weaker than C. virginica. We conclude that, because C. ariakensis exposed to predators continued to have a weaker shell relative to C. virginica, the natural suite of crab and flatworm predators in Chesapeake Bay will likely serve to control the abundance of feral C. ariakensis. We caution that the situation in the natural environment may be sufficiently different in some locations that C. ariakensis may be able to compensate for its greater vulnerability to crab predation and hence become a nuisance species.     

Achondrogenesis type II (Langer–Saldino) in association with jugular lymphatic obstruction sequence

The prenatal diagnosis of achondrogenesis in association with cystic hygroma is described. Ultrasound findings of severe short-limbed dwarfism, decreased vertebral ossification, and normal ossification of the calvarium were all consistent with achondrogenesis type II. Although the unusual finding of associated cystic hygroma raised the suspicion of a concurrent chromosome abnormality, the karyotype of both fetal lymphocytes and fetal fibroblasts was normal. Autopsy confirmed dilated lymphatic channels in the basal endothelial layer of the skin, cystic hygroma, and coarctation of the aorta. Although previously unreported, we suggest that the features of this case of achondrogenesis indicate an association with lymphatic stasis and jugular lymphatic obstruction sequence in this syndrome.     

Inhibition of pancreatic carboxypeptidase A: A possible mechanism of interaction between penicillic acid and ochratoxin A

Abstract

Penicillic acid and ochratoxin A are environmentally important toxic fungal metabolites (mycotoxins) that are synergistic in combination. The effects of penicillic acid on the pancreatic enzyme, :arboxypeptidase A were investigated in vitro and in vivo. A broad range of inhibition in vitro of the enzyme by PA was demonstrated with a half‐maximal inhibitory concentration equal to 1.1 x 10^‐4M PA. Inhibition of carboxypeptidase A was time and temperature dependent, and resulted in decreased conversion of parent ochratoxin A to the non‐toxic metabolite, ochratoxin alpha. Studies in vivo demonstrated a penicillic acid‐dependent inhibition of pancreatic carboxypeptidase A activity in the mouse and the chicken following multiple oral exposure. It is postulated that the mode of toxic interaction of the two mycotoxins may be due, in part, to impaired detoxification of ochratoxin A through peni‐cillic acid depletion of carboxypeptidase A activity.