The Structure of the Water-Holding Feathers of the Namaqua Sandgrouse

The morphology and fine structure of the feather barbules of the Namaqua Sandgrouse Pterocles namaqua are investigated histologically and experimentally by means of light microscopy, scanning electron micrography and X-ray diffraction. Proximally the barbule is helically coiled for three and a half turns and has a kidney-shaped, concave/convex transverse section. The inner concave surface is pitted, the outer convex surface smooth. The barbule is solid, consisting of three layers, and bears a number of appendages at its distal end, where it is more rounded in transverse section. The uncoiling of barbules from the abdominal feathers on contact with water may be initiated by water uptake and further facilitated by the number of helical coils at the base of the barbules. The keratin is fairly crystalline when dry. This crystallinity is somewhat reduced on wetting. The uncoiling mechanism is related to the expansion of the polypeptide chains of Il-keratin in order to accommodate additional water bound to the side chains

Review of the projected impacts of climate change on coastal fishes in southern Africa

The coastal zone represents one of the most economically and ecologically important ecosystems on the planet, none more so than in southern Africa. This manuscript examines the potential impacts of climate change on the coastal fishes in southern Africa and provides some of the first information for the Southern Hemisphere, outside of Australasia. It begins by describing the coastal zone in terms of its physical characteristics, climate, fish biodiversity and fisheries. The region is divided into seven biogeographical zones based on previous descriptions and interpretations by the authors. A global review of the impacts of climate change on coastal zones is then applied to make qualitative predictions on the likely impacts of climate change on migratory, resident, estuarine-dependent and catadromous fishes in each of these biogeographical zones. In many respects the southern African region represents a microcosm of climate change variability and of coastal habitats. Based on the broad range of climate change impacts and life history styles of coastal fishes, the predicted impacts on fishes will be diverse. If anything, this review reveals our lack of fundamental knowledge in this field, in particular in southern Africa. Several research priorities, including the need for process-based fundamental research programs are highlighted

Is the timing of spawning in sparid fishes a response to sea temperature regimes?

Published spawning seasons of sparid fish were investigated to determine if there were consistent patterns that could be related to large-scale physical variability, and whether these relationships were species-specific or characteristic of higher taxonomic groupings. For individual species, genera and the family Sparidae as a whole, there was a consistent pattern; spawning at lower latitudes was concentrated close to the month of lowest sea surface temperature, while spawning at higher latitudes was more variable with greater deviations from the month of minimum sea surface temperature. The distribution of sparids may be limited by a lack of tolerance of one or more early life-history stage to high water temperatures, so targeting spawning to the coolest part of the year could be a tactic allowing maximum penetration into warmer waters. Such a link between the physiology of early life-history stages and timing of spawning could have direct consequences for patterns of distributions over a number of taxonomic scales. If there are similar constraints on the reproduction of other species, even minor increases in water temperature due to global warming that may be within the tolerance of adults, may impose constraints on the timing of spawning, with flow-on effects for both species and whole ecosystems