Stock-recruitment relations controlled by feeding interactions alone

Stock-recruitment (S-R) relationships are the centrepiece of fisheries management aimed at achieving maximum sustainable yield (MSY). Here we consider the possibility that the density dependence evident in S-R relations is controlled by feeding interactions alone. We simulate a food-web model with dynamic representations of intra- and interspecific size structure and a linear relation between food intake and hatchling production of adults. Population sizes of individual stocks are modified by imposing additional mortality. The predominant functional forms and the steepness of resulting S-R relationships agree well with observations. We conclude that recruitment is plausibly regulated by feeding interactions alone.

Estimating biomass, fishing mortality, and "total allowable discards" for surveyed non-target fish

Demersal fisheries targeting a few high-value species often catch and discard other "non-target" species. It is difficult to quantify the impact of this incidental mortality when population biomass of a non-target species is unknown. We calculate biomass for 14 demersal fish species in ICES Area VIIg (Celtic Sea) by applying species-and length-based catchability corrections to catch records from the Irish Groundfish Survey (IGFS). We then combine these biomass estimates with records of commercial discards (and landings for marketable non-target species) to calculate annual harvesting rates (HR) for each study species. Uncertainty is incorporated into estimates of both biomass andHR. Our survey-based HR estimates for cod and whiting compared well with HR-converted fishing mortality (F) estimates from analytical assessments for these two stocks. Of the non-target species tested, red gurnard (Chelidonichthys cuculus) recorded some annual HRs greater than those for cod or whiting; challenging "Pope's postulate" that F on non-target stocks in an assemblage will not exceed that on target stocks. We relate HR for each species to two corresponding maximum sustainable yield (MSY) reference levels; six non-target species (including three ray species) show annual HRs >= HRMSY. This result suggests that it may not be possible to conserve vulnerable non-target species when F is coupled to that of target species. Based on biomass, HR, and HRMSY, we estimate "total allowable catch" for each non-target species.

Alternate wetting and drying irrigation for rice in Bangladesh: Is it sustainable and has plant breeding something to offer?

The crop management practice of alternate wetting and drying (AWD) is being promoted by IRRI and the national research and extension program in Bangladesh and other parts of the world as a water-saving irrigation practice that reduces the environmental impact of dry season rice production through decreased water usage, and potentially increases yield. Evidence is growing that AWD will dramatically reduce the concentration of arsenic in harvested rice grains conferring a third major advantage over permanently flooded dry season rice production. AWD may also increase the concentration of essential dietary micronutrients in the grain. However, three crucial aspects of AWD irrigation require further investigation. First, why is yield generally altered in AWD? Second, is AWD sustainable economically (viability of farmers' livelihoods) and environmentally (aquifer water table heights) over long-term use? Third, are current cultivars optimized for this irrigation system? This paper describes a multidisciplinary research project that could be conceived which would answer these questions by combining advanced soil biogeochemistry with crop physiology, genomics, and systems biology. The description attempts to show how the breakthroughs in next generation sequencing could be exploited to better utilize local collections of germplasm and identify the molecular mechanisms underlying biological adaptation to the environment within the context of soil chemistry and plant physiology.

Characterisation of the performance of sustainable grout containing bentonite for geotechnical applications

The grouts used in sealing or backfilling boreholes should ideally be selected to be compatible with the insitu field instruments installed in the borehole and also be engineered to match closely the geotechnical properties of the parent soils. A stable grout can be made using cement with various proportions of bentonite. The grout stability is very important during both the liquid and set conditions. The liquid grout fluidity should be as viscous as possible to avoid segregation, yet fluid enough to be easily pumpable and fill voids and over-break in the borehole. This paper investigates the effect of bentonite on the fresh and rheological properties of cement-based grouts in order to develop a stable grout to be used in these geotechnical situations. These properties were evaluated by the mini-slump flow, marsh cone flow time, Lombardi plate cohesion meter, static bleeding, yield stress and plastic viscosity values. Additionally, the compressive strength at 3 days, 7 days and 28 days were also investigated. The key parameters investigated were the dosages of bentonite and water-to-binder ratio (W/B). Test results showed that the dosage of bentonite had a significant effect on the fluidity, rheological properties and compressive strength of grout. The increase in the dosage of bentonite led to increasing the values of flow time, plate cohesion meter, yield stress and plastic viscosity, and reducing the mini-slump results, the static bleeding and the compressive strength at 3 days, 7 days and 28 days. Conversely, the increase in W/B led to decreasing the values of flow time, plate cohesion meter, yield stress, and plastic viscosity and the compressive strength, while increasing the mini-slump results and bleeding. Some recommendations for suitable mix proportions for use in soil boreholes are made.

Ionic liquid gel materials: applications in green and sustainable chemistry

Ionic liquid gel materials offer a way to further utilise ionic liquids in technological applications. Combining the controlled and directed assembly of gels, with the diverse applications of ionic liquids, enables the design of a heady combination of functional tailored materials, leading to the development of task specific / functional ionic liquid gels. This review introduces gels and gel classification, focusing on ionic liquid gels and their potential roles in a more sustainable future. Ionic liquid gels provide the ability to build functionality at every level, the solid component, the ionic liquid, and any incorporated active functional agents. This allows materials to be custom designed for a vast assortment of applications. This diverse class of materials has the potential to yield functional materials for green and sustainable chemistry, energy, electronics, medicine, food, cosmetics, and more. The discussion of the development of ionic liquid gel materials for applications in green and sustainable chemistry centres on uses of ionic liquid gels in catalysis and energy.