The Long-term Illinois River fish population monitoring program, Annual Report

Report issued on: March 2003Annual ReportINHS Technical Report prepared for Illinois Department of Natural Resource

Droplet impact onto an elastic plate: a new mechanism for splashing

During a droplet impact onto a substrate, splashing is known to be caused by the presence of surrounding gas or by surface roughness. Impact occurring in a vacuum onto a smooth rigid wall results in droplet spreading, rather than development of a corona or prompt splash. Here we present an analytical and numerical study of a third potential splashing mechanism, namely elastic deformation of the substrate. An axisymmetric Wagner-style model of droplet impact is formulated and solved using the method of normal modes, together with asymptotic analysis and numerical methods. We highlight the effect that a flexible substrate brings to the contact line velocity and jet behaviour, demonstrating that oscillation of the substrate can cause blow-up of the splash jet which is absent for a rigid substrate and indicate the onset of splashing

Impact of liquid droplets with deformable surfaces

During a droplet impact onto a substrate, splashing is known to be caused by the presence of surrounding gas or by surface roughness. Impact occurring in a vacuum onto a smooth rigid wall results in droplet spreading, rather than development of a corona or prompt splash. In this thesis we present an analytical and numerical study of a third potential splashing mechanism, namely elastic deformation of the substrate. An axisymmetric Wagner-style model of droplet impact is formulated and solved using the method of normal modes, together with asymptotic analysis and numerical methods. We highlight the effect that a flexible substrate brings to the contact line velocity and jet behaviour, demonstrating that oscillation of the substrate can cause blow-up of the splash jet which is absent for a rigid substrate and indicate the onset of splashing. In chapter 4 we investigate the important role air plays in the pre-impact behaviour of a liquid droplet approaching a solid substrate. A model for the air cushioning of a liquid droplet approaching a partially flexible solid substrate is developed using asymptotic and complex analysis methods. The model is solved numerically using boundary elements and method of normal modes. We show the presence of an elastic plate causes a slowing of the impact and if positioned directly underneath the droplet reduce the overall impact pressure. When the plate is not placed symmetrically touch down is found at only one location, with this touch down point having significantly higher impact pressures than initially anticipated. Finally in chapter 5 we develop a model for the impact of a liquid droplet with an attached air cavity. This preliminary model couples the various parameters inside the gas to the classical Wagner approach for liquid impact and allows us to investigate the evolution of the air cavity and its impact on the motion of the contact points

Fish community response to in-channel woody debris in a channelized river system

Additions of large wood (LW) have become a go-to technique for recovering altered river ecosystems. However, successful applications of this technique are generally limited to unchannelized rivers and headwater streams. Channelization of rivers, that is, engineering river channels to reduce recruitment and retention of in-channel structure, may, by definition, limit success of this restoration technique. Moreover, sufficient time has passed (a century or more) since initial channelization of many large rivers that portions of the fish community associated with LW may have become extirpated. Thus, the maxim that LW leads to a positive fish community response may not hold true. We examined fish community associations in habitats with and without LW in the channelized Missouri River to gain an understanding of the role of LW in large, channelized rivers. There were some differences between habitats with wood present compared to those without, but the differences were not evident once year, season and channel modifications intended to create aquatic habitat were taken into account. We assert that careful planning is necessary to ensure that additions of LW in channelized rivers are made to appropriate locations such that it will be retained in-channel for use as fish habitat and that LW-associated species are found in the system

Epidemic spread of smut fungi (Quambalaria) by sexual reproduction in a native pathosystem

Quambalaria are fungal pathogens of Corymbia, Eucalyptus and related genera of Myrtaceae. They are smut fungi (Ustilaginomycota) described from structures that resemble conidia and conidiophores. Whether these spore forms have asexual or sexual roles in life cycles of Quambalaria is unknown. An epidemic of Q. pitereka destroyed plantations of Corymbia in New South Wales and Queensland (Australia) in 2008. We sampled 177 individuals from three plantations of C. variegata and used AFLPs to test hypotheses that the epidemic was spread by asexual reproduction and dominated by a single genotype. There was high genotypic diversity across ≥600 AFLP loci in the pathogen populations at each plantation, and evidence of sexual reproduction based on neighbour-net analyses and rejection of linkage disequilibrium. The populations were not structured by host or location. Our data did not support a hypothesis of asexual reproduction but instead that Q. pitereka spreads exclusively by sexual reproduction, similar to life cycles of other smut fungi. Epidemics were exacerbated by monocultures of Corymbia established from seed collected from a single provenance. This study showcases an example of an endemic pathogen, Q. pitereka, with a strictly outbreeding life cycle that has caused epidemics when susceptible hosts were planted in large monoculture plantations

Phylogeny of the Quambalariaceae fam. nov., including important Eucalyptus pathogens in South Africa and Australia

The genus Quambalaria consists of plant-pathogenic fungi causing disease on leaves and shoots of species of Eucalyptus and its close relative, Corymbia. The phylogenetic relationship of Quambalaria spp., previously classified in genera such as Sporothrix and Ramularia, has never been addressed. It has, however, been suggested that they belong to the basidiomycete orders Exobasidiales or Ustilaginales. The aim of this study was thus to consider the ordinal relationships of Q. eucalypti and Q. pitereka using ribosomal LSU sequences. Sequence data from the ITS nrDNA were used to determine the phylogenetic relationship of the two Quambalaria species together with Fugomyces (= Cerinosterus) cyanescens. In addition to sequence data, the ultrastructure of the septal pores of the species in question was compared. From the LSU sequence data it was concluded that Quambalaria spp. and F. cyanescens form a monophyletic clade in the Microstromatales, an order of the Ustilaginomycetes. Sequences from the ITS region confirmed that Q. pitereka and Q. eucalypti are distinct species. The ex-type isolate of F. cyanescens, together with another isolate from Eucalyptus in Australia, constitute a third species of Quambalaria, Q. cyanescens (de Hoog & G.A. de Vries) Z.W. de Beer, Begerow & R. Bauer comb. nov. Transmission electron-microscopic studies of the septal pores confirm that all three Quambalaria spp. have dolipores with swollen lips, which differ from other members of the Microstromatales (i.e. the Microstromataceae and Volvocisporiaceae) that have simple pores with more or less rounded pore lips. Based on their unique ultrastructural features and the monophyly of the three Quambalaria spp. in the Microstromatales, a new family, Quambalariaceae Z.W. de Beer, Begerow & R. Bauer fam. nov., is described