Abstract

Within freshwater systems, crayfish play notable roles by shaping habitats and linking food web levels. Yet even with such influence, knowledge about numerous species is incomplete, which hinders protection strategies. Found only in the Neches River basin in eastern Texas, Procambarus nechesae and Procambarus nigrocinctus have different conservation statuses, mainly because data on their life history remains sparse. These two species are not closely related and are analyzed independently in this study. Research into traits tied to survival and environmental preferences was carried out so that informed decisions on conservation efforts can be made for these species. The goal of this study is to examine life history characteristics and environmental preferences of P. nechesae and P. nigrocinctus by completing five specific objectives: 1) analyze overall efficiency of field capture methods; 2) determine the length relationships and size classes for the target species; 3) analyze sex ratios and reproductive activity of the species; 4) determine optimal water and habitat characteristics based on environmental associations of these species; 5) analyze soil composition factors. Throughout 2025, five sites were sampled monthly within the Neches River drainage basin using minnow traps set with bait alongside uniform kick netting methods. Biological traits, reproduction, and environmental characteristics such as chemical makeup of water, structure of living spaces, and earth materials were noted separately for each species. A total of 2,391 individual crayfish records were collected, among them 1,212 belonging to P. nechesae, and 139 to P. nigrocinctus. The highest capture numbers for both species were in the spring. Water chemistry analysis found that P. nechesae was associated with turbid waters, and P. nigrocinctus aligned strongly with higher dissolved oxygen levels. Variation among sampling locations and season shaped surrounding conditions, accounting for a large share - 64 % - of chemical shifts in aquatic settings. P. nechesae was more likely found in low flow areas, while P. nigrocinctus was found in faster-moving areas with broken surface flow. Differences in associated habitat characteristics stem from the physical layout of space and water chemistry composition. Because these associations differ between species, care must be taken when designing protection efforts for native crawfish within the Neches drainage.

Date of publication

Spring 5-8-2026

Document Type

Thesis

Language

english

Persistent identifier

http://hdl.handle.net/10950/5061

Committee members

Matthew Greenwold, Joshua Banta, Katrin Kellner, Jared Dickson, Archis Grubh

Degree

Masters in Biology

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