Trampling impacts on thermotolerant vegetation of geothermal areas in New Zealand.

Geothermal features such as geysers, mud pools, sinter terraces, fumaroles, hot springs, and steaming ground are natural attractions often visited by tourists. Visitation rates for such areas in the Taupo Volcanic Zone of New Zealand are in the order of hundreds of thousands annually. These areas are also habitat for rare and specialized plant and microbial communities that live in the steam-heated soils of unusual chemical composition. We evaluated historical and current trampling impacts of tourists on the thermotolerant vegetation of the Waimangu and Waiotapu geothermal areas near Rotorua, and compared the results to experimental trampling at a third site (Taheke) not used by tourists. Historical tourism has removed vegetation and soil from around key features, and remaining subsoil is compacted into an impervious pavement on which vegetation recolonization is unlikely in the short term. Social tracks made by tourists were present at both tourist sites often leading them onto hotter soils than constructed tracks. Vegetation height and cover were lower on and adjacent to social tracks than further from them. Thermotolerant vegetation showed extremely low resistance to experimental trampling. This confirms and extends previous research that also shows that thallophytes and woody shrubs, life forms that dominate in thermotolerant vegetation, are vulnerable to trampling damage. Preservation of these vulnerable ecosystems must ensure that tourist traffic is confined to existing tracks or boardwalks, and active restoration of impacted sites may be warranted.

Anti-A and anti-B titers in pooled group O platelets are comparable to apheresis platelets.

BACKGROUND: Although uncommon, acute hemolytic transfusion reactions (AHTRs) have been reported after transfusion of group O single-donor apheresis platelets (SDPs) to group A, B, and AB recipients. Current methods for identifying "high-titer" SDPs include tube and gel methods. The risk of a high-titer unit is considered low with group O, poststorage, pooled platelet concentrates (PPLTs); however, data regarding anti-A and anti-B titers in PPLTs are lacking. STUDY DESIGN AND METHODS: Anti-A and anti-B titers were determined in 185 PPLTs by direct agglutination using manual gel and tube methods. PPLTs tested included 124 group O PPLTs, 25 group A PPLTs, 26 group B PPLTs, and 10 PPLTs containing a mix of either groups O plus A or groups O plus B (mixed PPLTs). The reciprocal of the highest dilution giving macroscopic agglutination was considered the agglutinin titer. RESULTS: Mean anti-A and anti-B titers in group O PPLTs were, respectively, 16 and 8 by tube and 64 and 32 by gel (p < 0.0001). Gel titers were one to two dilutions higher than tube and sensitive to reagent red cell lots. With the use of at least 64 as a critical titer, 60 percent of group O PPLTs tested by gel would be considered high-titer. In mixed PPLTs, the addition of one non-group O PLT significantly decreased or neutralized the corresponding anti-A or anti-B (p < 0.0001). CONCLUSION: Anti-A and anti-B titers in group O PPLTs are comparable to those reported in group O SDPs and significantly lower than titers reported in AHTR. A critical direct agglutinin titer of 64 for identifying high-titer units by gel is too low and should be increased to 128 or higher.