Ecophysiological responses of fishes to increasing ocean acidification and warming

A major goal in conservation biology is to understand the effects of short and long term environmental change on organisms. Fishes are the most valuable marine resource, however very little is known about the synergistic effect of current ocean warming and acidification, and the role of body size and local adaptation on their resilience. There is growing evidence that increased environmental temperature correlates with a reduction in ectotherm body size, suggesting a universal response to warming. To investigate the potential advantage of small body size in fish resilience, I made intra- and inter-specific comparisons of dwarf- and normal-size cleaner gobies of the genus Elacatinus. I first tested the hypothesis that smaller body size would correlate with a wider thermal tolerance by using same-age but different-size gobies reared at 'common garden' conditions. By employing critical thermal methodology, I provided empirical evidence supporting thermal biology theories that predict wider thermal tolerance windows as body size shrinks. These results provided the motivation to examine the effect of body mass on digestive performance, an indicator of fitness. Only smaller fish increased digestive metabolic scope at higher temperatures, thus suggesting that temperature increase caused by global warming will favor smaller individuals. To investigate the role of local adaptation on resilience in climate change, I compared the responses to warming and acidification between latitudinally- and morphologically-distinct populations of the little skate Leucoraja erinacea, by focusing on the most vulnerable life stages, embryos and juveniles. Embryos maintained at common garden conditions showed countergradient variation in performance curves. In juvenile skates, post-exercise metabolic curves shifted performance optima, exhibiting thermal adaptation in the two populations examined. This suggests that as skates hatch and are able to thermoregulate, they can change their temperature optima to exploit local thermal environments. Lastly, temperature and acidification levels predicted by the end of the century may reduce fitness of the northern population of skates, thus increasing vulnerability to local extinction

Automated image processing of x-radiographics of digestion in stingrays

This paper presents the development of an application for digital image processing of x-rays of stingrays. In order to measure the rate of absorption at varying temperatures, stingrays were fed detectable ball bearings. Using image processing techniques similar to digital mammography before the development of PACS, ball bearings and anchor points are detected in 111 scanned x-ray images of stingrays. Automatic measurements of distance between the ileum and the ball bearings are taken. The application incorporates image processing techniques and a graphical user interface. The development of the application to automate the measurement process is discussed, as well as its potential use, and its modification for use for different species of aquatic life.Conference ProceedingsPre-prin