SUMMARY It has been 10 years since human metapneumovirus (HMPV) was identified as a causative agent of respiratory illness in humans. Since then, numerous studies have contributed to a substantial body of knowledge on many aspects of HMPV. This review summarizes our current knowledge on HMPV, HMPV disease pathogenesis, and disease intervention strategies and identifies a number of areas with key questions to be addressed in the future.

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Guri Reservoir in Venezuela supports sport fisheries for two cichlid species (pavón venado or speckled pavon Cichla temensis and pavó n mariposa C. orinocensis) and payara Hydrolycus scomberoides. The lake receives acidic, hyperoligotrophic ''black waters'' from the Caroní River and experiences water level fluctuations associated with seasonal precipitation and hydroelectric operations. During the early 1980s, piscivore populations expanded in the new reservoir, but the quality of sportfishing declined during the 1990s. During 1993-94, we studied the ecology of the two Cichla species, H. scomberoides, and a fourth piscivore, Plagioscion squamosissimus (curvinata or silver croaker) and compared our data with those from similar surveys performed 7-9 years earlier (0-2 years after attainment of the reservoir's current crest height). Seine and gill-net samples from the lake's northern region produced 50 fish species from 18 families. Seine samples were dominated by a small characid, Hemigrammus micropterus, whereas gill-net samples were dominated by a large detritivorous characiform, Prochilodus rubrotaeniatus. Gill-net catch rates were low in all three surveys. All four piscivores from our recent survey had better body condition than in a 1985-1986 study, an indication of possible growth compensation. Diet breadths of all piscivores were low, and diet overlap was low for H. scomberoides with the two Cichla species and for P. squamosissimus with C. orinocensis. Hydrolycus scomberoides and C. temensis consumed significantly larger prey than P. squamosissimus, and differences in the relative proportions of specific characid and cichlid fishes consumed by the two Cichla species indicate that they forage at different depths within the littoral zone. The combined effects of hyperoligotrophic waters entering the reservoir, reduced inputs of dissolved nutrients from submerged terrestrial vegetation, low retention time of the reservoir, and harvest probably influence the low abundance of the two Cichla species in Guri Reservoir.

Wind is a persistent force in arid and semiarid lands. Microphytic crusts have been attributed with the ability to reduce wind erosion because of soil binding qualities. The purpose of this research was to determine if microphytic crusts contribute to soil stability in an arid land setting. Threshold friction velocity is the wind speed necessary for the initiation of soil erosion and, thus, is a measure of soil surface stability. A portable wind tunnel was used to determine threshold friction velocity on soil surfaces consisting of microphytic crusts living and undisturbed (control), chemically killed microphytic crusts but otherwise undisturbed (chemically killed), and microphytic crusts mechanically removed from the soil surface (scalped) to approximate conditions of absence. Significantly lower threshold friction velocities were measured within the scalped treatment than in the control or chemically killed treatments. Threshold friction velocities were not significantly different among control and chemically killed treatments. Significantly more wind-eroded material, entrained in the airstream and trapped by an inline filter, was obtained from the scalped treatment than from chemically killed or control treatments. Additionally, wind erosion occurred at significantly lower wind speeds in the scalped treatment. Microphytic crusts helped contribute to soil stability by binding soil particles, mainly by linked strands of cyanobacteria. Additional designed experiments are warranted to determine how the stabilizing influence of microphytic crusts are affected by type, degree, frequency, and season of disturbance and to answer pragmatic questions of concern to managers, such as determining acceptable levels of crust disruption and the wind speeds associated with erosion.