Cooperation between scientists, NGOs and industry in support of sustainable fisheries: the South African hake Merluccius spp. trawl fishery experience.

This paper examines the increasingly close interaction between natural and social scientists, non-governmental organizations (NGO) and industry, in pursuit of responsible ecosystem-based management of fisheries. South Africa has committed to implementing an ecosystem approach to fisheries management. Management advice stems from multi-stakeholder representation on government-led scientific and management working groups. In the hake Merluccius capensis and Merluccius paradoxus fishery, the primary management measure is an annual total allowable catch (TAC), the level of which is calculated using a management procedure (MP) that is revised approximately every 4 years. Revision of the MP is a consultative process involving most stakeholders, and is based on simulation modelling of projected probable scenarios of resource and fishery dynamics under various management options. NGOs, such as the Worldwide Fund for Nature in South Africa (WWF-SA), have played an important role in influencing consumers, the fishing industry and government to develop responsible fishing practices that minimize damage to marine ecosystems. Cooperation between industry, government and scientists has helped to improve sustainability and facilitated the meeting of market-based incentives for more responsible fisheries. Research includes ecosystem modelling, spatial analysis and ecosystem risk assessment with increasing research focus on social and economic aspects of the fishery. A four-year cooperative experiment to quantify the effect of trawling on benthic community structure is being planned. The food requirements of top predators still need to be included in the TAC-setting formulae and more social and economic research is needed. This paper also demonstrates how NGO initiatives such as Marine Stewardship Council certification and the Southern African Sustainable Seafood Initiative, a traffic light system of classifying seafood for consumers, have contributed to responsible fishing practices, increased ecosystem research and public awareness. This fishery appears to have a good future, provided that the monitoring, control and surveillance systems continue to function, TACs remain within ecologically sustainable limits and the effective collaboration between government, industry, scientists and NGOs continues to drive positive change.

Phenotypic plasticity and growth temperature: understanding interspecific variability.

The subject of this review is the impact of long-term changes in temperature on plant growth and its underlying components. The discussion highlights the extent to which thermal acclimation of metabolism is intrinsically linked to the plasticity of a range of biochemical and morphological traits. The fact that there is often a trade-off between temperature-mediated changes in net assimilation rates (NAR) and biomass allocation [in particular the specific leaf area (SLA)] when plants are grown at different temperatures is also highlighted. Also discussed is the role of temperature-mediated changes in photosynthesis and respiration in determining NAR values. It is shown that in comparisons that do not take phylogeny into account, fast-growing species exhibit greater temperature-dependent changes in RGR, SLA, and NAR than slow-growing plants. For RGR and NAR, such trends are maintained within phylogenetically independent contrasts (i.e. species adapted to more-favourable habitats consistently exhibit greater temperature-mediated changes than their congeneric counterparts adapted to less-favourable habitats). By contrast, SLA was not consistently more thermally plastic in species from favourable habitats. Interestingly, biomass allocation between leaves and roots was consistently more plastic in slow-growing species within individual phylogenetically independent contrasts, when plants were grown under contrasting temperatures. Finally, how interspecific variations in NAR account for an increasing proportion of variability in RGR as growth temperatures decrease is highlighted. Conversely, SLA played a more dominant role in determining interspecific variability in RGR at higher growth temperatures; thus, the importance of SLA in determining interspecific variation in RGR could potentially increase if annual mean temperatures increase in the future.

Effects of gamma radiation on Brugia malayi infective larvae and their intracellular Wolbachia bacteria.

Prior studies have shown that irradiated filarial larvae are developmentally stunted but capable of inducing partial immunity to filariasis in animals. The mechanisms for these effects are poorly understood. Recent studies suggest that intracellular Wolbachia bacteria are necessary for the normal development, reproduction and survival of filarial nematodes. The purpose of this study was to examine the effects of irradiation on Wolbachia in Brugia malayi infective larvae (L3) and on L3 development. The L3 were exposed to 0, 25, 35, 45, 55, 65 or 75 krad of gamma irradiation from a (137) Cesium source and cultured in vitro at 37 degrees C in NCTC/IMDM medium with 10% FCS for 12 days. Irradiation prevented molting of L3 to the L4 stage in a dose-dependent manner. Electron microscopy studies showed that irradiation damaged Wolbachia (25 krad) or cleared them from worm tissues (45 krad). In addition, majority of the irradiated L3s failed to develop the L4 cuticle. Real-time PCR studies showed that irradiation reduced Wolbachia DNA in worm tissues. Parallel in vivo studies confirmed decreased development of irradiated L3 in jirds, with associated effects on Wolbachia. Jirds injected s.c with normal L3 developed antibodies to Wolbachia surface protein (wsp) shortly after the onset of microfilarial patency. In contrast, jirds injected with irradiated L3 did not develop microfilaremia or antibodies to wsp. Additional studies are needed to test the hypothesis that irradiation retards growth and development of filarial L3 by killing Wolbachia.

Increased extracellular dopamine in the nucleus accumbens of the rat elicited by a conditional stimulus for food: an electrochemical study.

Stearate-modified graphite paste electrodes were implanted chronically into dopamine terminal regions in the nucleus accumbens or caudate nucleus of the rat. Reverse dialysis was used to demonstrate a selective response of these electrodes to dopamine, but not 3,4-dihydroxyphenylacetic acid or ascorbic acid. In a separate behavioural experiment, a significant increase in the chronoamperometric response was observed during presentation of a conditional stimulus predictive of food, and the electrochemical response remained elevated during and following consumption of the meal. Similar trends were observed from electrodes in the caudate nucleus. These data confirm the activation of mesolimbic dopamine neurons by incentive stimuli predictive of food and possibly by consumption of food. Together with other recent data on sex- and thirst-related increases in dopamine levels in the nucleus accumbens, these findings are consistent with a role for the nucleus accumbens as an interface between motivation and activation of the motor system.

Sexual behavior increases c-fos expression in the forebrain of the male rat.

The ability of a wide variety of pharmacological and physiological stimuli to increase neuronal expression of Fos has led to the suggestion that it might serve as a marker of neuronal activation. Psychomotor stimulants increase the release of dopamine from the terminals of nigrostriatal and mesolimbic neurons and enhance Fos immunoreactivity in the striatum and nucleus accumbens (NAc). Because sexual behavior also increases dopamine release in these and other forebrain regions, the present study examined the effect of copulation on Fos immunoreactivity in the forebrain of intact, sexually active male rats. Sexual behavior produced a striking increase in Fos immunoreactivity in the medial preoptic area (MPOA), NAc, bed nucleus of the stria terminalis and piriform cortex. However, no increase in Fos immunoreactivity was observed in the striatum. These results are consistent with neurochemical, physiological, and behavioral data suggesting that the MPOA and NAc are important substrates of sexual behavior.