Date of Award

1990

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

John B. Malone, Jr

Abstract

A geographic information system (GIS) was used to assemble and analyze data on the spatial distribution of habitat of the snail, Fossaria bulimoides, an intermediate hose of Fasciola hepatica. A model of habitat was developed on a single 760ha farm on the Chenier Plain of southwestern Louisiana and extrapolated for testing on 12 other farms in a 29,000ha extended study area of the Chenier Plain region. Input maps were: (1) soil series (type), (2) fencelines, (3) F. bulimoides habitat, and (4) soil salinity. On the primary study farm, habitat was strongly associated with interfaces of marsh and chenier (relict beach) soils, more consistently along a chenier waveface than on the backslope. On the 12 new farms, 23 per cent of snail habitat was found on chenier-marsh interfaces, most of this along interfaces adjacent to relatively broad cheniers; 61% of snail habitat occurred within the Hackberry-Mermentau (Hm) complex of soil series on broad cheniers, above interfaces. The proportion of farm occupied by F. bulimoides habitat regressed significantly against the proportion of farm comprised of Hm soil (p = 0.024, r$\sp2$ = 0.416, slope = 0.165). Results indicate that a successful soil-based model for estimation of snail habitat distribution on the chenier plain region should include the area of soils of the Hackberry-Mermentau complex as well as the interfaces of marsh and cheniers. Although snail habitat was localized to Hackberry-Mermentau soils and chenier-marsh interfaces on broad cheniers, no consistent relationship was shown in the present study between soils and fecal egg shedding by adult cattle on 10 farms.

Pages

131

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