68 research outputs found

    Passing the Panda Standard: A TAD Off the Mark?

    Get PDF
    Tilapia, a tropical freshwater fish native to Africa, is an increasingly important global food commodity. The World Wide Fund for Nature (WWF), a major environmental nongovernmental organization, has established stakeholder dialogues to formulate farm certification standards that promote ‘‘responsible’’ culture practices. As a preface to its ‘‘tilapia aquaculture dialogue,’’ the WWF for Nature commissioned a review of potential certification issues, later published as a peer-reviewed article. This article contends that both the review and the draft certification standards subsequently developed fail to adequately integrate critical factors governing the relative sustainability of tilapia production and thereby miss more significant issues related to resource-use efficiency and the appropriation of ecosystem space and services. This raises a distinct possibility that subsequent certification will promote intensive systems of tilapia production that are far less ecologically benign than existing widely practiced semiintensive alternatives. Given the likely future significance of this emergent standard, it is contended that a more holistic approach to certification is essential

    The ecophysiology of under-ice fauna

    No full text
    During exposure to low salinity, the under-ice amphipods Gammarus wilkitzkii and Onisimus glacialis appeared as euryhaline osmoregulators, displaying regulation of haemolymph concentrations of sodium and chloride. Free amino acids took part in the regulation. During freezing and brine formation, the amphipods were freeze-sensitive and did not tolerate being frozen into solid ice. However, they could stay in the vicinity of the ice, conforming osmotically to the ambient brine and thus lowering the melting point of the amphipods' body fluids. This prevented internal ice formation in the absence of antifreeze agents (THF) in the haemolymph. When G. wilkitzkii, O. glacialis and Apherusa glacialis were exposed to dilute seawater, elevated rates of oxygen consumption and ammonia excretion were observed. The O:N atomic ratio was kept nearly constant during hyposmotic stress, indicating protein/lipids as metabolic substrate. Rates of oxygen consumption and ammonia excretion increased with increasing osmotic differences between the haemolymph and the medium, indicating higher energy requirements for osmotic and ionic regulation at low salinities. A minor decrease in haemolymph sodium concentrations coincided with the increased ammonia output during hyposmotic stress, indicating a possible counter ion regulation of NH+4 and Na+. An increased rate of oxygen consumption, ammonia excretion and 0:N ratio versus temperature was observed for all species
    • 

    corecore