Population Characteristics Of The Crayfish, Cambarus Bartoni, In Lakes With And Lakes Without Introduced Populations Of Smallmouth Bass, Micropterus Dolomieui, In Algonquin Provincial Park, Ontario

Populations of the crayfish Cambarus bartoni from six lakes in Algonquin Provincial Park, Ontario were compared to evaluate the influence of an introduced predator, the smallmouth bass Micropterus dolomieui. Bass were introduced into lakes in the southern portion of the park in the late 1800\u27s and early 1900\u27s. Crayfish populations from three lakes containing bass were contrasted with populations from three lakes without bass.;Comparisons of relative abundances, patterns of habitat use and length-frequency distributions were compromised by seasonal changes in crayfish trappability and differences in crayfish species composition. Catches of C. bartoni in baited traps were lower in lakes containing bass and in lakes with greater numbers of co-occurring crayfish species. The presence of bass did not affect trap catches of C. bartoni from different habitats. Length-frequency distributions of trap catches varied among lakes with no consistent pattern associated with the presence of bass, but trap catches contained proportionately more large crayfish in lakes with more crayfish species.;Frequency of cheliped loss among populations of C. bartoni was highest in lakes with more crayfish species. Only females displayed increased incidences of claw loss in lakes with bass. Female C. bartoni in two lakes containing bass were characterized by a smaller size at sexual maturity. Females from the third lake with bass exhibited a size at maturity similar to populations from lakes without bass, yet smaller females produced proportionately more eggs than similarly sized females in any of the other lakes. Ovarian egg counts indicated that size-specific fecundity was higher among populations from lakes containing bass. However, the magnitude of the increase in fecundity ranged from 4 to 35% above values from populations in lakes without bass.;C. bartoni from lakes containing bass differed morphologically from crayfish in lakes without bass. Populations experiencing bass predation displayed a common form characterized by a more robust carapace, larger chelipeds and a smaller rostrum. The magnitude of sexual dimorphism was reduced in lakes with more crayfish species. However, the presence of bass reduced the influence of the number of crayfish species and enhanced sexual divergence in morphology

An assessment of spatial and temporal variation in the diet of Cape clawless otters (Aonyx capensis) in marine environments

We studied the diet of Cape clawless otters (Aonyx capensis) at three sites along the eastern and southern coast of South Africa to assess possible spatial variation along a community species richness and biomass gradient associated with rocky shores.A total of 309 spraints representing two seasons (summer 2013/2014 and winter 2014) were collected and subsequently analysed. The percentage occurrence and percentage dry mass of numerous prey categories were compared between sites and seasons. Variation in the importance of prey items was found between sites, whilst no variation was found between seasons within the same site. Crab was the most important prey item in the southernmost study area (Tsitsikamma National Park) and at the northernmost study site (KwaZulu-Natal Coast), whilst lobster was the most important prey item in the central area (Mkambati Nature Reserve). Fish was the second most important prey item at all three sites. Our results suggest that otters are opportunistic feeders that are likely able to adapt to potential prey species and abundance changes associated with current and future anthropogenically driven changes. Furthermore, long-term, site-specific stability in diet suggests that monitoring the diet of otters could provide some useful information on the status of shoreline communities.The South African Department of Science and Technology through the National Research Foundation, and by a University of Pretoria Research Development Programgrant (T. McIntyre).am201

Deleuze, Freud and the Three Syntheses

The aim of this paper is to provide a close reading of Deleuze's complex account of Freud's Beyond the Pleasure Principle in Difference and Repetition. The first part provides a reading of Beyond the Pleasure Principle itself, showing why Freud feels the need to develop a transcendental account of repetition. In the second, I show the limitations of Freud's account, drawing on the work of Weismann to argue that Freud's transcendental model mischaracterises repetition. In the third part, I show how Freud's account of the death drive is shadowed by Deleuze's own non-representational transcendental account

Tracking the triple form of difference: Deleuze's Bergsonism and the Asymmetrical Synthesis of the Sensible

This paper will explore the notions of intensity, the virtual/actual and different/ciation in Gilles Deleuze's work. It will focus in particular on excavating the Bergsonian dimension of these terms in Deleuze's philosophy and their relations to one another. While much has been written on the role of Bergson in shaping Deleuze's virtual/actual philosophy, far less attention has been paid to the way in which Deleuze's thoughts on intensity and the movements of different/ciation are also developed out of his reading of Bergson. To address this I will explicate the 'triple form of difference' that Deleuze locates in Bergson, which includes renditions of intensity and the process of differentiation, after which I will map the movements from this early Bergsonian work to Deleuze's mature position on the matter, as it is found in the final chapter of Difference and Repetition

Confirmation of co-denitrification in grazed grassland

Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N₂) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N₂ losses in vivo and fewer still have examined the relative contribution of the different N₂ emission processes, particularly in grazed pastures. We used a combination of a high ¹⁵N isotopic enrichment of applied N with a high precision of determination of ¹⁵N isotopic enrichment by isotope-ratio mass spectrometry to measure N₂ emissions in the field. We report that 55.8 g N m⁻² (95%, CI 38 to 77 g m⁻²) was emitted as N₂ by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m⁻²), compared to only 1.1 g N m⁻² (0.4 to 2.8 g m⁻²) from denitrification. This study provides strong evidence for co-denitrification as a major N₂ production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems

Time Out of Joint: Hamlet and the Pure Form of Time

The aim of this paper is to explore why Deleuze takes up Hamlet’s claim that ‘time is out of joint’. In the first part of this paper, I explore this claim by looking at how Deleuze relates it to Plato’s Timaeus and its conception of the relationship between movement and time. Once we have seen how time functions when it is ‘in joint’, I explore what it would mean for time to no longer be understood in terms of an underlying rational structure. The claim can be understood as about a relationship between time and action. In the second part of this paper, I want to relate this new understanding of time to Hamlet itself, in order to see how temporality operates within the play. I will conclude by relating these two different conceptions of time out of joint to one another through Nietzsche’s Eternal Return

The interplay of local and regional factors in generating temporal changes in the ice phenology of Dickie Lake, south-central Ontario, Canada

Ice-on date occurred significantly later over 1975–2009 at Dickie Lake, Ontario, while ice-off date showed no significant trend, differing from many other records in North America. We examined the ice phenology using 3 modelling approaches: a lake-specific regression model to derive a suite of local predictors; a regionally derived regression model to test larger-scale predictors; and a physically based, one-dimensional thermodynamic model. All 3 models were also applied to generate future ice cover scenarios. The local regression revealed air temperature to be an important predictor of ice phenology in our area, as reported elsewhere; however, reductions in wind speed and increases in lake heat storage over the last 35 years also contributed significantly to a delayed ice-on date. Ice-off dates were strongly correlated with the effects of warmer air temperatures but also influenced by increased snowfall and reduced wind speed. Thus, although changes in ice phenology were related to continental-scale changes in air temperature, they were also influenced by more localized climatic variables, and a careful examination of local events was needed for a complete assessment of ice phenology. Predictabilities of the regional regression model, which primarily relied on air temperature to predict phenology, and the physically based model were lower than the lake-specific local regressions, reinforcing the need for inclusion of local variables when greater accuracy is important. Finally, the 3 methods generated similar estimates of reductions in ice cover over the next 90 years, predicting a 40–50 day decrease in ice season length by 2100

Touring the Hidden City: Walking Tour Guides in Deindustrializing Genoa

Drawing on ethnographic research conducted in Genoa, a northern Italian city whose deindustrialization process began in the early 1970s, this paper explores how the city’s high levels of intellectual unemployment have given rise to the profession of walking tour guides. These are highly educated women, and more rarely men, who, working independently of the financial and political powers that usually drive urban revitalization processes, utilize their cultural capital and talents to spin itinerant tales of concealment and discovery around the master narrative of Genoa’s decline and its tourist potential. Through an analysis of their professional histories and experiences as well as the ways they present the city, I argue that the guides comprise a sui generis “creative class” (Florida 2012) that helps transform Genoa into a city worth visiting. In their attempt to boost cultural tourism, tour guides inhabit a liminal space from where they vie for legitimacy, build professional personas that both challenge and reinforce gender norms, and straddle contested lines between high and popular culture, and between amateurism and professionalism. I contend that, compared with Richard Florida’s (2012) upwardly mobile “talents,” Genoa’s walking tour guides form a residual creative class that emerges out of necessity and struggles to survive by creatively exploiting the “hiddenness” of a densely layered cityscape