Settlement-Subsistence Variability In The Glenwood Locality,Southwestern Iowa

Abstract

Central Plains tradition settlement distribution in Southwest Iowa is poorly understood. Patterns of both nucleated and dispersed forms seem to be represented. The known distribution in the Glenwood locality is examined and an algorithm presented that could explain the existing variability. Initial locality occupants relied heavily on hunting and gathering with minimal horticulture during the Neoatlantic climatic episode. Isolated homesteads were an efficacious adaption. During the dryer Pacific climatic episode attendant reduction of natural resources forced intensified horticulture which eventuated a more nucleated settlement pattern.     

Bovine thelaziasis in Iowa

The prevalence of developing Thelazia nematodes in face flies (Musca autumnalis) was studied for 7 yr at a beef farm in central Iowa. Juvenile nematodes were not found among flies in reproductive diapause in autumn, nor among nulliparous, overwintered flies in spring, but only among actively reproducing insects. Thus Thelazia probably do not overwinter in face flies. A mean prevalence of 2.0% infected was recorded among flies in 7 fly breeding seasons. No heterogeneity in Thelazia prevalence was detected within fly breeding seasons. The frequency distribution of Thelazia among face flies by year of occurrence was homogeneous, with a mean of 2.75 larval nematodes per infected fly. Thelazia gulosa and T. skrjabini were recovered in necropsy from the eyes of bovines from central Iowa. Prevalence among fat cattle 18-27 mo old was 15%; among cows 3-15 yr old, prevalence was only 3%. Thelazia skrjabini was found in 29 eyes and T. gulosa in 4 eyes. Infections were randomly distributed among the eyes of subject cattle. The mean worm burden was 2.3 T. skrjabini and 12 T. gulosa per infected eye. Thelaziasis is clearly enzootic in Iowa.     

Community Analyses of Plant-Parasitic Nematodes in the Kalsow Prairie,Iowa

Twenty-one species of plant-parasitic nematodes were recovered from 15 sites in the Kalsow Prairie, Iowa. Nematode communities were analyzed by prominence and importance values of the nematode species and also by diversity and concentration of dominance. The use of numbers and biomass were compared in indices of diversity and concentration of dominance. Tylenchorhynchus maximns ranked first in mean density/site, prominence value, and importance value, although it was not found as frequently as many other nematodes. Xiphinema americanum and T. maximus were among the dominant nematodes in 11 of 15 sites when biomass was used in the concentration-of-dominance index, but they were dominant in only five sites when numbers were used.     

Causal Assessment of Biological Impairment in the Little Floyd River,Iowa, USA

An assessment of biological impairment in the Little Floyd River (Iowa, USA) was based on evidence of three characteristics of causation: co-occurrence, preceding causation, and sufficiency. Evidence of the physical interaction of the probable causes and the biota, resulting alterations to the biota, as well as the time order of the cause and the effect were consistent within the assessment, but the evidence for these causal characteristics did not discriminate among probable causes or other causes. Deposited sediment, low dissolved oxygen, heat stress, and ammonia toxicity are the probable causes of impaired biological condition in the Little Floyd River compared with other rivers in the ecoregion. Less likely causes are suspended sediment, altered basal food resources, and flow alteration. Very unlikely causes are pH shifts, total dissolved solids, Cyprinus carpio (an invasive species), metal toxicity, and pesticides. Data were insufficient to assess salinity or other toxicants. The assessment was used to develop a recovery plan for the stream. This assessment demonstrates that, even when there are many candidate causes and uncertainties are substantial, the probable causes of biological impairments can be determined with enough certainty to inform decision-making to address environmental problems.     

A New Sphenopsid Cone from Iowa

A new Pennsylvanian cone genus (Litostrobus iowensis, n. gen.,n. sp.), apparently of sphenophyllalean affinity, is describedon the basis of a coal-ball specimen from the Urbandale Mine,Urbandale, Iowa. The cone is small and extremely simple in organization.It consists of superposed whorls of twelve bracts each. Thebases of the bracts are fused to form shallow cuplike discs.Six sporangia are produced in each whorl; they are erect, eachterminating a short, thick, axillary pedicel. Small spores withhighly distinctive ornamentation are present in the sporangia. Comparison with other previously described sphenopsid fructificationsreveals morphological differences that warrant recognition ofthe Urbandale specimen as a new genus.