The Edwards-Trinity Aquifer System of Texas, USA, one of the world's most ecologically diverse groundwater systems, contains 14 species (across seven genera) of small, poorly studied freshwater snails. Their underground habitat and microscopic size make them difficult to study and identify. Most published records are from original species descriptions, and some have not been seen since they were described more than 100 years ago. Here we use ∼150 new collections, including spring and hyporheic zone sampling from across the Texas portions of the Edwards-Trinity Aquifer System, to update the ranges of these species. Two species were very uncommon, if encountered at all; individuals that might be Phreatodrobia imitata were seen at one sampling location, and a single individual of P. punctata was encountered once. The most frequently encountered snail, P. nugax, can be highly abundant and is found across a wide range. Other notable findings include the rediscovery and greatly expanded range of Stygopyrgus bartonensis, the Barton Cavesnail, as well as range extensions of 100 km or more for several species.

The Cochliopidae of Texas include both stygobitic species, those that occupy only underground habitats, and epigean species, those living only in aboveground habitats. The devil tryonia, Tryonia diaboli, was described from the Devils River of Texas from river wrack, without additional habitat information. This species has been largely ignored since its description, so details of its habitat and ecology are obscure. In Dolan Springs and Finegan Springs, flowing into the Devils River, we sampled macroinvertebrates at five sites that form a gradient from the aquifer to the mainstem Devils River. We found the highest abundances of T. diaboli in aquifer samples, decreasing sharply downstream from the spring orifice. Our findings indicate that T. diaboli is stygophilic, occupying a transitional area including the aquifer as well as aboveground portions of springs.

A total of 260 specimens of native freshwater mussels and numerous specimens of three introduced bivalves were photographed and published in The Freshwater Mussels of Tennessee, but the provenance and disposition for these specimens were not included. All but nine of the 260 bookplate freshwater mussel specimens and all of the introduced bivalve specimens used in the figures were recently found. Information on length, catalogue number, collection locality, date of collection, and collector(s) is provided herein.

While freshwater mussels are often negatively impacted by large reservoirs, the influence of smaller low-head dams on resident mussel fauna is variable. A 2017 planned dewatering of Robinson Lake, a small water-supply reservoir located in the Llano River, Texas, presented an opportunity to quantify the native unionid community. We also compared unionid communities between Robinson Lake and a riverine portion of the mainstem Llano River to assess how impoundments may influence assemblage structure, and we evaluated the conservation implications for two Endangered Species Act (ESA) candidate species. In total, we salvaged and relocated 1,012 live unionids representing five species from Robinson Lake, including ESA-candidate species Lampsilis bracteata and Cyclonaias petrina. Lentic specialists were observed exclusively in Robinson Lake, while lotic specialists and habitat generalists occurred in the Llano River. Though community composition differed, we did observe overlap among sites, suggesting that Robinson Lake contains a subset of the unionid community within nearby riverine reaches, and it supports more lentic-adapted species. Contrary to previous habitat assessments, observations of L. bracteata reproduction in Robinson Lake suggests that this species is able to adapt to lacustrine environments and establish populations within small impoundments, though catch rates suggest higher densities in lotic habitats. As increased utilization of water resources and changing climactic patterns continue to impact spring-fed river systems of the Edwards Plateau region, such impoundments may become important conservation units for L. bracteata during major drought conditions.

Although much less common in ecotoxicology than traditional single-generation studies, multigenerational studies may offer a deeper understanding of the chronic and population-level effects caused by contaminants. To evaluate the potential utility of multigenerational contaminant studies and develop a feasible generational test design, we conducted a two-generational toxicity test using the freshwater File Ramshorn snail (Planorbella pilsbryi). Adults were exposed to five sublethal concentrations of copper, which resulted in significant delays in reproduction with increasing copper exposure and complete reproductive inhibition at the highest concentration (75.0 µg/L). Mortality and inhibition of reproduction were not observed in the control and three lowest concentrations (4.7, 9.4, and 18.8 µg/L Cu) over the course of the exposure and during recovery in clean water, indicating no lasting adverse effects. However, subsequent exposure of the unexposed juveniles that were produced during the recovery period (i.e. those not directly exposed to copper) showed that juveniles born to copper-exposed parents (LC50: 11.57 µg/L Cu; 95% CI: 3.71–19.43 µg/L Cu) were significantly less tolerant to copper exposure than juveniles born to unexposed parents (LC50: 29.25 µg/L Cu; 95% CI: 22.17–36.32 µg/L Cu). Despite no obvious changes in parental reproductive success, the fitness of unexposed juveniles was compromised due to parental exposure.