Migratory gauntlets on oceanic islands: Watershed disturbance increases the cost of amphidromy

Migratory fishes can be threatened by conditions encountered along dispersal pathways that impede access to feeding or breeding grounds. In this study, we tested the hypothesis that amphidromous fishes are equally or more sensitive to conditions along dispersal pathways than conditions in primary residential habitats. We did so by conducting distribution‐wide population surveys of all five amphidromous gobies native to the Hawaiian Islands to assess responses to in‐stream habitat, invasive species and watershed land use. We used Redundancy Analyses to assess whether goby densities varied according to local, downstream or upstream conditions. We found that population densities of the two non‐climbing species (Eleotris sandwicensis, Stenogobius hawaiiensis) varied according to local land use and local habitat conditions. Greater densities of E. sandwicensis also were found in watersheds with greater forest cover upstream of survey sites. Lower densities of two species that migrate farther inland (Awaous stamineus, Sicyopterus stimpsoni) were observed in watersheds with greater anthropogenic land use downstream or at the stream mouth. Population densities of E. sandwicensis and both Sicydiine species (Lentipes concolor, S. stimpsoni) also were lower when non‐native Poeciliids were locally present or present downstream in the watershed. These findings suggest that densities of native Hawaiian amphidromous fishes are equally or more sensitive to conditions along migratory pathways relative to conditions in primary residential habitats. Thus, alleviating pressures by removing invasive species and restoring habitat along dispersal pathways could be effective approaches to increasing densities of amphidromous species, especially those that migrate farther inland to higher elevations.     

Lifelong population connectivity between large rivers and their tributaries: A case study of shovelnose sturgeon from the Mississippi and Wisconsin rivers

Fishes that depend on large‐river habitats have declined in many regions due to human alteration of both mainstems and tributaries. Conserving these species is often complicated by their dependence on long‐distance movements to complete their life cycle, but the location of key habitats is difficult to assess across multiple life history stages. Movement of large‐river fishes between mainstems and major tributaries is commonly observed, but the role of these exchanges at the population level is uncertain. We used shovelnose sturgeon (Scaphirhynchus platorynchus) as a case study for assessing the lifelong spatial ecology of large‐river fishes. Fin ray microchemistry data indicate that shovelnose sturgeon from the Mississippi and Wisconsin rivers represent a unified population that relies on connections among multiple large‐river habitats throughout life history. The tributary serves as an important spawning area, but fin ray chemistry data suggest larvae subsequently drift downstream to nursery habitats in the mainstem; an assertion that is supported by extensive field survey data. Our analyses underscore the lifelong importance of connections within river networks for maintaining viable populations of this, and likely other large‐river species that have been documented to use tributary habitats. These findings support a metapopulation perspective on species that depend on large‐river habitats, many of which are now highly altered and fragmented. For shovelnose sturgeon and species with similar life history, protecting or restoring linkages between mainstem rivers and their tributaries should be a conservation priority.     

Coccoliths as paleoclimatic indicators of pleistocene glaciation

Selected species of Coccolithophoridae from recent sediments and mid-Wisconsin glacial sediments of the North Atlantic were examined in an attempt to determine cooling effects. All species showed a definite shift southward during the glacial period. The average shift in this planktonic population was 15 degrees of latitude, with the greatest change in the eastern Atlantic. A paleoisotherm map can be drawn on the basis of the temperature boundaries of coccolithophorids. The species boundaries indicate a possible shift in position of the subtropical gyral to a glacial position roughly parallel to the 33-degree line of latitude.     

Improving the nutritional status of food-insecure women: first, let them eat what they like

OBJECTIVE: To determine the extent to which identified nutrient inadequacies in the dietary intakes of a sample of food-insecure women could be ameliorated by increasing their access to the 'healthy' foods they typically eat. DESIGN: Merged datasets of 226 food-insecure women who provided at least three 24-hour dietary intake recalls over the course of a month. Dietary modelling, with energy adjustment for severe food insecurity, explored the effect of adding a serving of the woman's own, and the group's typically chosen, nutrient-rich foods on the estimated prevalence of nutrient inadequacy. SETTING AND SUBJECTS: One study included participants residing in 22 diverse community clusters from the Atlantic Provinces of Canada, and the second study included food bank attendees in Toronto, Ontario, Canada. Of the 226 participants, 78% lived alone with their children. RESULTS: While nutritional vulnerability remained after modelling, adding a single serving of either typically chosen 'healthy' foods from women's own diets or healthy food choices normative to the population reduced the prevalence of inadequacy by at least half for most nutrients. Correction for energy deficits resulting from severe food insecurity contributed a mean additional 20% improvement in nutrient intakes. CONCLUSIONS: Food-insecure women would sustain substantive nutritional gains if they had greater access to their personal healthy food preferences and if the dietary compromises associated with severe food insecurity were abated. Increased resources to access such choices should be a priority.     

A molar pregnancy in an embryo donor cow

A 6-year-old Hereford embryo donor cow was referred to Auburn University College of Veterinary Medicine for a mass in the tip of her left uterine horn. The cow had recently undergone an embryo collection which yielded unfertilized, degenerated ova. Transrectal palpation and ultrasound revealed a multi-locular mass enveloped by two separate compartments that resembled an amniotic and allantoic cavity within the uterus. Tissue was collected via a uterine flush and submitted for histopathology. The tissue was determined to be placenta, confirming the diagnosis of a molar pregnancy. Following treatment, the cow was able to produce numerous viable embryos. Molar pregnancies are rare and characterized by abnormal growth of trophoblastic cells leading to formation of intrauterine cystic masses. It is important to routinely perform an ultrasonographic examination of the cow's reproductive tract approximately 30 days following non-surgical in vivo embryo collections to detect and treat unwanted conditions such as pregnancy and cystic conditions.     

Cattle temperament: persistence of assessments and associations with productivity, efficiency, carcass and meat quality traits

Relationships between temperament and a range of performance, carcass, and meat quality traits in young cattle were studied in 2 experiments conducted in New South Wales (NSW) and Western Australia (WA), Australia. In both experiments, growth rates of cattle were assessed during backgrounding on pasture and grain finishing in a feedlot. Carcass and objective meat quality characteristics were measured after slaughter. Feed intake and efficiency during grain finishing were also determined in NSW. Brahman (n = 82 steers and 82 heifers) and Angus (n = 25 steers and 24 heifers) cattle were used in the NSW experiment. In NSW, temperament was assessed by measuring flight speed [FS, m/s on exit from the chute (crush)] on 14 occasions, and by assessing agitation score during confinement in the crush (CS; 1 = calm to 5 = highly agitated) on 17 occasions over the course of the experiment. Brahman (n = 173) and Angus (n = 20) steers were used in the WA experiment. In WA, temperament was assessed by measuring FS on 2 occasions during backgrounding and on 2 occasions during grain feeding. At both sites, a hormonal growth promotant (Revalor-H, Virbac, Milperra, New South Wales, Australia) was applied to one-half of the cattle at feedlot entry, and the Brahman cattle were polymorphic for 2 calpain-system markers for beef tenderness. Temperament was not related (most P > 0.05) to tenderness gene marker status in Brahman cattle and was not (all P > 0.26) modified by the growth promotant treatment in either breed. The Brahman cattle had greater individual variation in, and greater correlations within and between, repeated assessments of FS and CS than did the Angus cattle. Correlations for repeated measures of FS were greater than for repeated assessments of CS, and the strength of correlations for both declined over time. Average FS or CS for each experiment and location (NSW or WA × backgrounding or finishing) were more highly correlated than individual measurements, indicating that the average values were a more reliable assessment of cattle temperament than any single measure. In Brahman cattle, increased average FS and CS were associated with significant (P < 0.05) reductions in backgrounding and feedlot growth rates, feed intake and time spent eating, carcass weight, and objective measures of meat quality. In Angus cattle, the associations between temperament and growth rates, feed intake, and carcass traits were weaker than in Brahmans, although the strength of relationships with meat quality were similar.     

Polymers: synthesis and characterization of extremely high-molecular-weight polystyrene

Polystyrenes with molecular weights up to 44 x 10(6) grams per mole have been characterized by light-scattering and equilibrium ultracentrifugation methods. The Mark-Houwink equation, which relates the molecular weight and the intrinsic viscosity of flexible polymers, can be used only if the measurements are made in a theta solvent at the theta temperature.