Christian Blanks, Michael Fraser, Brennan Mader, Rhett Melancon, Youngho Shin

The growing number of encounters between humans and American crocodiles (Crocodylus Acutus) in Costa Rica has raised significant concerns, requiring effective conservation measures. To address this issue, a comprehensive tracking system for location and physiology is being developed to gain a deeper understanding of the behavior and habitat preferences of the crocodiles. The system comprises multiple sensors—including GPS, motion sensors, pressure sensors, and a MEMS microphone—that transmit data via satellite communications. Furthermore, the system integrates low-power management algorithms with a solar panel system to maximize its lifespan while affixed to crocodiles in the jungles of Costa Rica. This system enables researchers to collect real-time data on crocodile movements, habitat preferences, and physiological conditions. The primary goal of deploying this system is twofold: first, to establish safe boundaries for human activities near crocodile habitats, and second, to support conservation efforts by closely monitoring the health and environmental stressors affecting the crocodile population. The ability to track these parameters in real-time will not only help prevent potential human-crocodile conflicts but also aid in the development of more informed conservation strategies.

Grayson Headrick, Logan Duff, Kaylie Cook, Christof Stumpf

A novel form of sequencing using nanopores by Oxford Nanopore Technologies (ONT) provides an inexpensive and convenient solution for introducing sequencing into undergraduate research. This study focuses on the mitochondrial genome of Faxonella creaseri, the Ouachita fencing crayfish. A nanopore is a nanoscale protein that facilitates the detection of DNA molecules by measuring voltage differences as they pass through the pore. In this research, genomic DNA was extracted from gill tissue and rapid adapters were linked to DNA fragments of varying sizes. The resulting library was loaded onto a R10.4.1 flow cell for the MinION Mk1C sequencer and run for 48 hours. The data was combined with results from a previous experiment. Data evaluation was performed with ONT’s app EPI2ME and the SAMtools bioinformatic application using the mt-DNA genome of Procambarus clarkii, the red swamp crayfish, as a reference. This approach successfully detected 15,749 nucleotides, similar to the 15,926 nucleotides in the P. clarkii genome. However, 226 nucleotides were unidentifiable. The quality scores of the runs averaged around 10, just above the cutoff of 8, and several regions of low coverage were identified. Future research will take a more traditional approach using established PCR primers combined with nanopore sequencing. Additionally, a more powerful sequencer capable of handling larger data sets in combination with long reads is being considered.

Sarah Moore, McKenzlea Wise, Juan Gonzalez, Christian Baker

Helminths are parasitic flatworms that infect various vertebrate animals. They can be particularly harmful in commercial fish populations, causing profit losses for producers due to reduced growth and increased mortality. In 2021, 30 channel catfish (Ictalurus punctatus) were collected from Natchitoches National Fish Hatchery (Natchitoches, LA). The gastrointestinal tract, musculature, and body cavity were examined for helminths. Within the sample population, three distinct species were identified based on morphology: Alloglossidium, Hysteromorpha, and Clinostomum. The goal of the current project is to use molecular analysis to validate the samples previously identified as Clinostomum. Two presumptive Clinostomum samples were chosen for further study. The genomic DNA was quantified, and a touchdown PCR protocol was performed using degenerate Platyhelminthes primers, followed by Sanger sequencing. The DNA sequences were compared to known sequences in the BLAST database. Sample A exhibited a 96% cover query and 99.36% match with Clinostomum marginatum. Sample B showed a 94% cover query and 86.79% match with Clinostomum poteae. We have confirmed that both samples are Clinostomum. Sample A has been confirmed to be C. marginatum, while the species-level identification of sample B is inconclusive. Further work is needed to definitively identify the presumptive C. poteae species. Future studies will also entail verification of Hysteromorpha and Alloglossidium samples. 

Claire Boudreaux, Timothy Clay

The Diamondback Terrapin is a turtle native to Louisiana’s coastal marshes. The IUCN describes Diamondback Terrapin populations as decreasing, and a main driver of this trend is incidental drowning in blue crab traps. Despite supporting the United States’ largest blue crab fishery, Louisiana does not require use of bycatch reduction devices (BRDs) on commercial traps. Terrapins are sexually dimorphic, with adult males smaller than females, and can be differentially affected by crabbing pressure. To understand how terrapin populations may be responding, a mark-recapture study was initiated in 2012 in Barataria Bay. In our data, we found a shift in adult sex ratios toward female dominant and an overall decrease in adult body size. We deployed crab traps at our site to investigate where terrapins interact with traps and impacts of BRDs. We have concluded that terrapins are locally at risk of capture in traps but BRDs can reduce terrapin entry without affecting legal crab catch. These studies highlight that in our population, adult female terrapins can become too large for capture in traps, but adult males do not reach sizes that prevent their capture. Our results suggests that juveniles and adult males likely face increased mortality risks from the blue crab fishery and corroborate previous studies conducted in commercially crabbed systems where terrapins occur. Furthermore, our data suggests that selective use of BRDs in Louisiana’s crab fishery should be considered.

Adam Quade, Guillaume Rieucau

Predation is often considered to be the primary driving force behind the formation of fish schools. Schooling generally improves safety through the actions of several anti-predatory mechanisms such as collective predator detection, risk dilution, or confusion effect. Observed variations in collective behaviors influenced by environmental context, predation risk, and anthropogenic disturbances suggests fish schools exhibit a high-degree of behavioral and structural plasticity. Thus, in complex and highly aquatic dynamic systems such as floodplains, it is important to assess how schooling fish assess and respond to the rapid and unpredictable variation in environmental conditions (e.g., pulse of floodwater) they are exposed to. Combining non-invasive high-resolution imaging-sonar technology and semi-automated tracking technology, we quantified how floodplain-associated schooling fish adjust their schooling tendencies and school topology (school area, polarization and inter-individual distances) across a latitudinal gradient of hydrologic connectivity in the Mississippi floodplain. 56 hours of high-resolution video data has been recorded with 6,307 schools documented. We found that fish formed denser schools when floodplain habitats were connected to the main-stem river, suggesting schooling fish may perceive these habitats as high-risk. Preliminary results indicate that the degree of floodplain inundation strongly affects school topology even under limited predation pressure.

Shelby Truckenbrod, Timothy Clay

Diamondback Terrapins (Malaclemys terrapin) inhabit brackish waters along the Atlantic and Gulf Coasts of the United States. Currently listed as vulnerable by the IUCN Red List, Diamondback Terrapins are threatened range-wide by anthropogenic activities such as the blue crab fishery and coastal development. In Louisiana, terrapins are state-listed as vulnerable (S3). Though imperative for conservation efforts, few studies regarding terrapins have been conducted in Louisiana, none of which investigated movement or habitat use. We employed a novel method to track terrapin movement via an automated UHF radio telemetry system deployed on a barrier island in Barataria Bay, Louisiana. Since August of 2022, 19 female and 19 male terrapins have been tagged with radio transmitters and continuously tracked within our radio telemetry system. Thus far, over 670,000 locations have been estimated for all terrapins with a mean of 17,856 locations per individual and a mean of 176 days tracked. We used linear mixed effects models to explore the effects of intrinsic, environmental, and temporal factors on hourly movements of terrapins. Overall, terrapin movement increases with higher tidal heights and higher temperatures. Larger hourly movements occurred diurnally and during mating and nesting seasons. Findings from this study will increase our understanding of the patterns and drivers of Diamondback Terrapin movement in Louisiana and aid in the development of conservation strategies.

Christiana Aseyomi, Harry Meyer

Tardigrades (water bears) are ecdysozoan animals found in moss and lichen, known for their ability to survive in the tun state in extreme environments. Calohypsibius is a genus with three species. Our goal is to determine the species of a Calohypsibius found in moss in Oregon, USA. The Oregon species most closely resembles Cal. ornatus, a species first described from Germany in 1900, and widely reported since then in reported in Asia, New Zealand, and North and South America, which has eight rows of spines. Its pattern of dorsal tubercles is consistent with Cal. ornatus. Our hypothesis is that the Oregon species is Cal. ornatus. Only 18s DNA data are available for Calohypsibius, and DNA is therefore unfortunately not useful for our purpose. One prominent feature in Cal. ornatus is rows of long dorsal and lateral spines. Using phase contrast microscopy we counted the lateral and dorsal spines in the eight rows. The number of dorsal spines varied within and among rows. The original and few subsequent published descriptions and images of Cal. ornatus vary considerably in spine numbers; none are fully consistent with Oregon values. We conclude that Oregon Calohypsibius is probably not Cal. ornatus sensu stricto, but without better molecular and morphometric data we cannot be certain.

O'Neal Edward

Presence of coarse woody debris and mast trees was compared between active Eastern woodrat nest sites and random points in a bottomland hardwood forest in Central Louisiana.  Camera and live trapping were used to determine whether woodrat nests were active.  Habitat data was collected at 33 active nest sites and an equal number of random points.  Coarse woody debris was defined as logs at least 30 cm in diameter and 25 cm in length. There was no evidence to indicate that woodrat nest sites were more likely to have a hard mast-producing tree withing 10 m than were random points.  However, woodrat nests were significantly more likely to be associated with coarse woody debris than were random points.  These results support the important role that coarse woody debris plays in habitat selection by small mammals.

Travis Bayer, María Camila Calderón-Capote, James Lee, Margaret Crofoot, Dina Dechmann, Teague O'Mara

Accelerometry-derived energy estimates based on dynamic body acceleration have been shown to represent quality measures of energy expenditure in birds and some terrestrial mammal species. However, the complex kinematics of bat flight may make these proxies for energy expenditure less accurate than in other taxa. For example, to increase travel speed, animals can increase the frequency that their limbs cycle or exert more force. Bats will instead often alter the kinematics of the flight such as the angle at which the wings are positioned during wingbeats to modulate their flight speed. This leaves uncertainty about the accuracy of acceleration-based estimates of energy expenditure. To validate relationships of energy expenditure and accelerometer-based movement in bats, we deployed both heart rate loggers along with GPS and triaxial accelerometers on individual greater spear-nosed bats. We used heart rate estimates of energy expenditure to develop relationships between dynamic body acceleration metrics and estimated energy expenditure. These relationships are then used to show movement-based energy landscapes – or the distribution of energy expenditure over space and time. Calibrated energy landscape perspectives allow the exploration of how and why individual bats make movement decisions, as well as more accurate estimates of the costs of their high-energy lifestyles.

Gretchen Hilt, Christopher Beachy, Dr. Kyle Piller

Developing non-invasive approaches is of great value to detect and monitor fragile populations of great conservation concern. Environmental DNA (eDNA) is becoming increasingly popular to study rare, threatened, and endangered species across many aquatic and terrestrial ecosystems. eDNA approaches are particularly attractive for species living in habitats that are difficult to access or sample. The Georgia Blind Cave Salamander, Eurycea wallacei, inhabits groundwater environments that are often inaccessible due to the need for cave-diving experience or simply the physical inability to access due to geological barriers. Modeling population trends of such elusive species may be substantially more attainable with an eDNA analytical approach. Here I propose a field survey to detect the presence and better elucidate the geographic distribution of E. wallacei using an eDNA approach in highly sensitive, understudied cave systems. Confirmation of E. wallacei presence will be quantified by amplifying a small region of the mitochondrial cytochrome b locus using a species-specific primer-probe assay. Determining detection thresholds of Eurycea wallacei eDNA will further enhance a safe, cost-effective, and efficient detection assay. Minimal disturbance is key in monitoring and protecting the species, which is feasible with a non-invasive analysis such as eDNA.