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In 2006, the Stroud Water Research Center conducted inventories of stream macroinvertebrates in the Peninsula de Osa in Costa Rica and the Madre de Dios watershed in eastern Peru. Both areas have extensive lowland tropical rainforests under threat from road development, tourism, poaching and gold mining. The mayfly communities of the two regions were substantially different in family relative abundances. In Osa the mayfly community was more or less evenly divided among Baetidae, Leptohyphidae, and Leptophlebiidae. In streams where one group was clearly dominant, this was most often Leptohyphidae. By contrast, in the Madre de Dios watershed Leptophlebiidae was often 75% or more of the mayfly fauna while Leptohyphidae was 20% or less. In both Osa and Madre de Dios, EPT indices were calculated for impacted streams and relatively undisturbed streams. However, physical characteristics such as stream size and substrate diversity were often a better predictor of community composition than human activity.

The genetic structure of Dolania populations in South Carolina, Alabama, and Florida was examined using starch gel electrophoresis. All study populations except Alabama consisted entirely of D. americana Edmunds and Traver. Electrophoresis revealed that the Alabama site contained both D. americana and an undescribed species (D. sp. nov.), with the latter taxon predominating. Individuals of the two taxa had nearly fixed allelic differences at two loci (Est 4 and Gda). The extent of genetic differentiation between populations of the two taxa in the same river or between adjacent river systems was significantly greater than between D. americana populations separated by large geographic distances. Populations of both species were characterized by relatively normal levels of polymorphic loci (average = 23%) but unusually low levels of heterozygosity (average = 0.03). Genetic variation between the Florida and South Carolina populations of D. americana was statistically significant. There was also some indicatio...