An approach for the identification of exemplar sites for scaling up targeted field observations of benthic biogeochemistry in heterogeneous environments

Continental shelf sediments are globally important for biogeochemical activity. Quantification of shelf-scale stocks and fluxes of carbon and nutrients requires the extrapolation of observations made at limited points in space and time. The procedure for selecting exemplar sites to form the basis of this up-scaling is discussed in relation to a UK-funded research programme investigating biogeochemistry in shelf seas. A three-step selection process is proposed in which (1) a target area representative of UK shelf sediment heterogeneity is selected, (2) the target area is assessed for spatial heterogeneity in sediment and habitat type, bed and water column structure and hydrodynamic forcing, and (3) study sites are selected within this target area encompassing the range of spatial heterogeneity required to address key scientific questions regarding shelf scale biogeochemistry, and minimise confounding variables. This led to the selection of four sites within the Celtic Sea that are significantly different in terms of their sediment, bed structure, and macrofaunal, meiofaunal and microbial community structures and diversity, but have minimal variations in water depth, tidal and wave magnitudes and directions, temperature and salinity. They form the basis of a research cruise programme of observation, sampling and experimentation encompassing the spring bloom cycle. Typical variation in key biogeochemical, sediment, biological and hydrodynamic parameters over a pre to post bloom period are presented, with a discussion of anthropogenic influences in the region. This methodology ensures the best likelihood of site-specific work being useful for up-scaling activities, increasing our understanding of benthic biogeochemistry at the UK-shelf scale

Dual role of the immune response in street rabiesvirus infection of mice

The cellular and humoral immune responses of mice to footpad injection of salivary gland suspensions of street rabiesvirus were investigated. Suppression of these responses with cyclophosphamide both increased the overall mortality rate from (50 to 100%) and delayed onset of disease signs and death for 1 to 2 weeks. Despite the absence of disease signs in these immunosuppressed animals, virus was present in the central nervous system, as shown by fluorescent-antibody staining of corneal epithelium. The onset of paralysis after limited immunosuppression was temporally related to a return to immune responsiveness, and passive transfer of homologous immune serum to infected immunosuppressed animals brought about their early paralysis and death. These findings indicate the importance of the immune response in the pathogenesis of street rabiesvirus infection.</jats:p

Weed Management in a Furrow-Irrigated Imidazolinone-Resistant Hybrid Rice Production System

Research was conducted in 2007 and 2008 to evaluate weed-control options in an imazethapyr-resistant rice production system. Raised beds were formed, and imidazolinone-resistant hybrid rice ‘CL 730’ was drill-seeded on beds. Five herbicide programs applied up to the four- to six-leaf stage of rice were evaluated with and without additional “as-needed” herbicide at later stages. All the herbicide combinations and as-needed herbicides tested in this research were labeled for rice, and only minor transient injury (&lt; 5%) was initially observed. Weeds emerged throughout the growing season, and as-needed herbicides were applied after the four- to six-leaf stage of rice to control these late-emerging weeds and weeds not effectively controlled with earlier applications, primarily Palmer amaranth. Most of the Palmer amaranth at this site was insensitive to imazethapyr (possibly acetolactate synthase resistant). Therefore, application of as-needed herbicides with different modes of action, such as 2,4-D, were used to improve Palmer amaranth control. Rice yields were often numerically higher in plots that received additional herbicide after the six-leaf stage of rice, but yields were not significantly improved.</jats:p