Influence of the physical environment and conspecific aggression on the spatial arrangement of breeding grey seals

Understanding the habitat requirements of a species for breeding is essential for its conservation, particularly if the availability of suitable habitat is a limiting factor for population growth. This is postulated to be the case for grey seals, one of the more abundant marine apex predators in northern European waters. In common with similar studies that have investigated the habitat preferences of breeding grey seals, we use abiotic (topographical, climatological) attributes but, unlike previous work, we also incorporate behavioural variables, particularly the occurrence of aggressive interactions between females and the presence of neighbouring seals. We used two Generalized Additive Models (GAM) in a sequential and iterative fashion. The first model links the occurrence of aggression at particular points in the colony to local topography derived from a Geographical Information System (GIS), presence of neighbouring seal pups and the day of the breeding season. The output of this GAM is used as one of the explanatory variables in a GAM of daily variation in the spatial distribution of births. Although proximity of a birth site to a water source and the presence of neighbouring seal pups both had significant influences on the distribution of newborn pups over time and space, at the scale of the study site it was found that simple rules could predict pup distribution more efficiently than a complex individual-based simulation model. (c) 2007 Elsevier B.V. All rights reserved.PostprintPeer reviewe

Do Diatoms beneath the Greenland Ice Sheet Indicate Interglacials Warmer than Present?

Basal sediment debris from the Greenland ice sheet was examined with the hope of recovering microfossils that could be used to determine and date changes in ice sheet size through time. Basal debris and debris-laden ice from the lower 18 m of the Camp Century ice core, northwest Greenland, revealed the presence of common freshwater and rare marine diatoms. These diatoms may have lived in the vicinity of the Camp Century site in the Late Neogene prior to development of the Greenland ice sheet. More likely, they lived during a Pleistocene interglacial period, when the volume of ice in the Greenland ice sheet was smaller than it is today and the site was ice free. A warmer and/or longer interglacial period than the present Holocene "interglacial" is suggested to explain the large decrease in ice sheet volume.Key words: diatoms, interglacial, Pleistocene, Camp Century ice core, GreenlandMots clés: diatomées, interglaciaire, Pléistocène, carotte de glace du Camp Century, Groenlan

A Notable Day at Iowa State College

Tuesday, March 15, was unique in the history of Iowa State College and the state of Iowa. For it was on that day that Iowa State College, speaking for education and the entire state, welcomed Governor Nate Kendall, Lieutenant Governor Hammill and the two newly appointed women members of the state board of education, Miss Anna B. Lawther and Mrs. James A. Deavitt

Breeding ecology of whimbrels (Numenius phaeopus) in Interior Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2016Whimbrels Numenius phaeopus breed in tundra-like habitats, both beyond treeline and within the boreal forest of interior Alaska. Despite their widespread distribution and designation as a species of conservation concern, their ecology has been particularly understudied in Alaska. During 2008--2012, I initiated the first dedicated study of Whimbrel breeding ecology in Alaska, and the first such study of any boreal-breeding shorebird in the state. Within a habitat mosaic of forest, woodlands, muskeg, scrub, and ponds within the floodplain of the Kanuti River in north-central Alaska, Whimbrels bred in the three largest (of nine) patches of discontinuous tussock tundra. These Whimbrels exhibited a compressed annual breeding schedule with the first birds arriving about 6 May and nests hatching about 17 June. Evidence for clustered and synchronous nesting, which may aid in predator defense, was equivocal. Most (69%) Whimbrels nested in mixed shrub-sedge tussock bog. I modeled nest-site selection at multiple spatial scales for 39 nests; however, the only variables important in the models were at the finest scale around the nest, namely that nests tended to be located on hummocks and exhibited lateral cover. Model results for nest survival of 67 nests over 4 years revealed a considerable difference in nest success (92% vs. 41%) at the two largest patches studied; this site effect was largely unexplained. To investigate Whimbrel ecology more broadly in the boreal biome, in 2013 I designed and conducted a Whimbrel-specific survey comprising 279 point counts within 28 transects along the road system of interior Alaska. I detected Whimbrels on just 32% of transects and 11% of count points. Although I detected Whimbrels at 3 sites where they had not been reported previously, I failed to detect them at several historically occupied sites. Dwarf shrub meadow was the most commonly observed habitat for all points visited. I modeled Whimbrel presence based on coarse habitat and avifaunal community features; no models were well supported. Between the local and regional surveys, my results tended to reinforce several widespread, but not necessarily investigated, descriptions about the breeding ecology of Whimbrels. My studies supported the premises that Whimbrels are patchily distributed on the landscape and often breed in clusters. Breeding of individuals and occupancy of some patches may be annually variable. Despite analyses of multiple habitat features at multiple spatial scales, I mostly observed a lack of specificity in where they bred among tundra-like patches, and where they nested specifically within such patches. This suggests that Whimbrels are tundra habitat generalists on their breeding grounds. Such phenotypic plasticity may be particularly adaptive in the dynamic, wildfire-prone landscape of interior Alaska

Isogrid design handbook

Handbook has been published which presents information needed for design of isogrid triangular integral-stiffened structures. It develops equations, methods, and graphs to handle wide variety of loadings, materials, and geometry. Handbook is divided into seven sections. Handbook may be used by marine and civil engineers and by students and designers without access to computers

An Unusual Hip Injury in a Male Soccer Player

Please refer to the pdf version of the abstract located adjacent to the title

Contribution à l'évaluation écotoxicologique du Tébuthiuron - un herbicide de la classe des urées substituées

Une étude écotoxicologique a été menée à l'égard du Tébuthiuron (TB), un phytocide homologué inhibant la croissance de végétation nuisible, afin de mieux cerner son impact sur le milieu aquatique susceptible d'être affecté par des épandages terrestres. La toxicité du TB a été évaluée en réalisant des bioessais à trois paliers écologiques, soit avec la truite arc-en-ciel (Salmo gairdneri), avec l'algue Selenaslrum capricornutum et avec la bactérie (Photobacterium phosphoreum) du système Microtox®. Parmi ces trois indicateurs, les algues se sont montrées les plus sensibles (C150 = 0,08 mg • L-1), suivies des truites (CL50 = 115 mg • L-1) et enfin, des bactéries du système Microtoxe (C150 - 328 mg • L-1). Des résidus maximaux variant de 0,091 à 0,18 mg • L-1 rapportés pour le TB en milieu aquatique, suite à des applications expérimentales, laissent donc croire que seules les algues pourraient étre victimes d'une agression marquée. D'autre part, les essais réalisés avec le SOS Chromotest ont démontré que le TB était faiblement génotoxique sans activation métabolique. En revanche, des algues exposées à 1 mg • L-1 de TB durant 4 heures n'ont pu ni (dés)actlver ni bioaccumuier l'herbicide. En général, notre enquéte corrobore certaines données générées pour fins d'homologation de ce produit, lesquelles concluaient en faveur de son innocuité relative à l'égard de l'environnement aquatique. Les effets chroniques que pourrait avoir une longue exposition de faibles concentrations de TB sur certains paliers écologiques devraient cependant faire l'objet d'lnvestigations futures.A wide array of chemical products are commonly used to inhibit the growth of a diversity of undesirable vegetation types for numerous purposes. In forestry applications, herbicides can improve ranges, contribute to sylviculture and facilitate rights-of-way management, for example. Among congeners of the substituted urea class herbicides, Tebuthiuron (TB) has proven efficient for such activities. Since its commercial appearance in 1974, this broad-spectrum weed killer was employed to control a variety of herbaceous and woody plants. When applied on soil before or during the onset of plant emergence, TB irreversibly affects photosynthesis after being absorbed by roots and translocated to its target sites. Prior to its registration as a herbicide, TB had undergone extensive (eco)toxicological testing which had generally indicated low potential for environmental concern, with regards to terrestrial and avian fauna. Although TB is generally purported to be unproblematic towards fish, the overall impact of substituted urea class herbicides is still not fully documented, as far as various members of the aquatic community are concerned. The experimental results presented herein - specifically on TB - contribute both confirmatory as well as some new information in this respect.In our study, TB toxicity was investigated at three ecological levels by undertaking acute bioassays with rainbow trout (Salmo gairdeneri), algae (Selenastrum capricornutum) and bacteria (Photobacterium phosphoreum). Among these bio-indicators, algae proved to be the most sensitive (EC50 = 0.08 mg • L-1), followed by rainbow trout (LC50 = 115 mg • L-1) and bacteria (EC50 = 328 mg • L-1). Since maximum TB residues lying between 0.091 and 0.18 mg • L-1 have been reported for aquatic systems following experimental terrestrial applications, our toxicity results suggest that only algae could be adversely affected following acute exposure to the herbicide.Additional tests performed with the SOS Chromotest, a bacterial colorimetric assay for detecting DNA-damaging agents, first showed that TB is weakly genotoxic without metabolic activation. Since recent genotoxicity studios have revealed that vegetal systems can either detoxify, activate or uptake specific chemicals, we then explored this possibility by exposing S. capricornutum (106 cells • mL-1) to 1 mg • L-1 of TB for 4 h. Results of this acute exposure indicated an absence of positive (detoxication) or negative (activation, accumulation) phytoplanktonic interactions. Indeed, the genotoxic characteristics of TB, before and after algal exposure, were unaltered, as demonstrated by SOS Chromotest assays. In this same experiment, a similar assay on TB-exposed algal cells (i.e. SOS Chromotest on an algal cell solvent extract) detected no genotoxic activity.In conclusion, our study corroborates existing data generated for TB registration purposes and essentially supports the notion that this chemical is relatively harmless towards the aquatic environment under normal use conditions. Nevertheless, an important caveat remains concerning chronic affects on specific organisms, which could result from long term exposure to low concentrations of TB. Since such potential effects have not yet been adequately addressed, further studios are warranted in this area