Prey preference for Asian carp and soft plastic lure ingestion by largemouth bass

Invasive bighead (Hypophthalmichthys nobilis) and silver carp (Hypophthalmichthys molitrix) have become established throughout much of the Mississippi River basin. In many areas, these two species comprise a significant proportion of the fish biomass. Despite their prevalence and potential for negative environmental impacts, to date, there has been no assessment of vulnerability to predation of Asian carp compared to native species. We sought to examine largemouth bass (Micropterus salmoides) predation on juvenile bighead and silver carp in relation to common native prey species. Prey species selection experiments in 2-m pools showed number of prey captures was highest for bighead carp followed by gizzard shad with lower capture rates for bluegill, golden shiner, and silver carp. Observations of prey and predator behavior were quantified in a 720-L aquarium and variation in anti-predator behavior explained relative differences in vulnerability to predation. Differences in vulnerability to predation may explain the greater invasion success of silver carp. Similar or higher vulnerability to predation of Asian carp compared to common native prey suggests that they may serve as viable prey for native predators mitigating the potential negative impacts on the native prey community. Soft plastic fishing lures (SPLs) have recently gained attention as a potential source of pollution in aquatic systems. A number of anecdotal reports have suggested that discarded SPLs are being ingested by wild fish and causing health problems including mortality. Few studies have been conducted concerning the effects of SPLs on fish. We designed a laboratory study to determine the effects of ingestion of three different shapes and two different materials of SPLs on consumption by largemouth bass. No effects on consumption were observed except on the first day after SPL ingestion. In three trials with 30 fish, all largemouth bass were ultimately capable of expelling the lures from their bodies. Field data were also utilized to determine the occurrence of SPL ingestion by largemouth bass in the wild. In two Illinois lakes, occurrence rates of SPL ingestion were < 1%. Bass sampled with SPLs in their stomach did not have significantly different body condition from fish that had not ingested SPLs. We conclude that discarded SPLs do not pose a significant threat to the health of largemouth bass. Nevertheless, we encourage efforts to responsibly dispose of SPLs in order to prevent pollution and any possible undiscovered consequences of their presence in the environment

Period Estimation and Noise in a Neutrally Stable Stochastic Oscillator

The periods of the orbits for the well-mixed cyclic three-species Lotka-Volterra model far away from the fixed point are studied. For finite system sizes, a discrete stochastic approach is employed and periods are found via wavelet analysis. As the system size is increased, a hierarchy of approximations ranging from Poisson noise to Gaussian noise to deterministic models are utilized. Based on the deterministic equations, a mathematical relationship between a conserved quantity of the model and the period of the population oscillations is found. Exploiting this property we then study the deterministic conserved quantity and period noise in finite size systems

Rule: a study of Jia Yi's "Xin shu"

Der hanzeitliche Politiker und Philosoph Jia Yi (200-168 v.Chr.) ist der wichtigste Denker seiner Zeit, das Xin shu das grundlegende Vermachtnis seiner Ideen. Diese Doktorarbeit analysiert das Xin shu als Ausdruck von Jia Yis politischen Theorien. Sie betrachtet Jia Yis Konzepte des Staatsvolkes und dessen Kontrolle sowie seine Ideen von der Natur und den Eigenschaften von Herrschaft und Herrscher. Der bedeutendste Begriff Jia Yis gegenuber politischer Macht ist Ritus, in drei Aspekten: Hierarchie, Portabilitat und Massigung. Sodann tragt die Arbeit die vorangegangene Diskussion in den Bereich des Konkreten und geht um Jia Yis Anwendung der Ritus-Theorie gegenuber zeitgenossischer Politik. Die beiden Schlusskapitel weiten die Analyse durch Betrachtung von zwei Einzelfallen aus: 1) das Prinzip, wonach die hochrangigen Untertanen des Kaisers von korperlichen Strafen befreit sein sollen; 2) die Behandlung der Xiongnu, deren Plunderungen eine Problematik der frühen Han Zeit waren