On contour crossings in contour-advective simulations - part 1 - algorithm for detection and quantification

This is the first of two papers devoted to the analysis of contour crossing errors that occur in contour-advective simulations of fluid motion. Here an algorithm is presented for quantifying the error due to contour crossings. The first step is to determine the relative proximity of all possible pairs of contours. A digital representation of each contour is produced to aid in the corresponding calculation. Simple analysis of functions is then used to find any crossings between contours deemed close to each other by the digital representation method. Next, the area in error of a pair of crossing contours is calculated by identifying the polygon or polygons that approximately bound the erroneous region. Finally, some preliminary results of analysis of contour crossings that occur in contour-advective semilagrangian (CASL) simulations of single layer quasigeostrophic turbulence are presented. It is shown that the error due to contour crossings is small in the simulations considered here

Movement Decisions and Foraging Behaviour in Shoals of Fish The influence of internal and external stimuli

This thesis explores the mechanisms and functions of decision-making in groups, specifically in the context of social foraging in fish shoals. While many animal groups may seem homogeneous to the naked-eye, closer inspection reveals considerable heterogeneity, as they are composed of individuals with different phenotypes and different motivations living in stochastic, complex environments. The question then, is how do individual behavioural decisions change under varying internal and external conditions and what effect does this have on group level decision-making? How do animals address conflicts of interest and competition effects whilst ensuring benefits of group living are maintained? The approach taken in this thesis has been to address these questions from many angles, using a range of freshwater and marine species and employing an array of novel experimental set-ups. Of particular importance has been the utilization of automated, multi agent tracking software, which has allowed for the description of the movement and interaction of individually identified fish at a much finer scale than in the past. This project has direct significance to our understanding of the individual and group dynamics of social species, which is a central theme in behavioural ecology, and will inform researchers in a variety of fields from theoretical biology to sociological studies of human grouping patterns. The inclusion of internal nutritional state and external environmental factors into studies of group movement and decision-making in a foraging context is a practical way of linking the mechanistic forces behind individual behaviour to functional group-level responses. This will help expand our understanding of the evolutionary causes of group living and its ecological consequences, influencing conservation management plans and strategies to improve fisheries and aquacultural practices