Elizabeth Granier, Giovanna McClenachan, Jonathan Willis

Louisiana’s barrier islands are geologically ephemeral coastal landforms created by the historic deltaic cycle of the Mississippi River. Although these barrier islands deteriorate relatively rapidly as a consequence of the combined impacts of chronic wave energy exposure and acute, high energy storm events, they are also highly valuable in terms of their ecosystem service provision.  In particular, the overall reduction of storm energy, protection of landward habitats and human infrastructure, and the provision of crucial nesting habitat for birds has led the State of Louisiana to make substantial investments in the restoration of these ecosystems. Barrier island restoration typically involves nourishment of the sand and sediments that constitute these coastal landforms, as well as planting of appropriate vegetation and the installation of sand fencing. Although the species selection and plantings protocols for effective, initial barrier island restoration are largely well developed, long term trends in vegetation community composition have not been thoroughly evaluated. To address this potential knowledge gap, existing monitoring data from the CPRA BICM program has been investigated through a series of ordination analyses to elucidate patterns in vegetation community composition subsequent to restoration activity.  Elucidation of barrier island vegetation community development after restoration will enable more informed coastal modeling and decision making.

Julia Jones

Bottomland hardwood forests are widespread habitats throughout the southeastern region of the United States that provide myriad ecosystem services, including carbon sequestration.  Because of the substantial degradation of these habitats that has occurred through anthropogenic impacts, extensive ecosystem restoration efforts are now being undertaken in many areas.  Such ecosystem restoration efforts provide an opportunity to optimize carbon sequestration capacity through the informed selection of target species for planting.  Considerable research has been undertaken to identify overstory species and environmental conditions that optimally promote carbon sequestration.  However, little research has been undertaken to assess the potential role of understory vegetation, such as Sabal minor, in augmenting carbon sequestration processes.  A field investigation has been undertaken in the Jean Lafitte National Park Barataria Preserve to determine the extent to which the abundance of S. minor, a species that exhibits both extensive ground coverage and high photosynthetic efficiency, could enhance soil carbon sequestration processes. Although data collection is still underway, analyses thus far suggest that plots with larger Sabal minor individuals also tend to have greater soil organic matter content, emphasizing the importance of inundation as a modulating factor in organic matter accumulation. 

Magdalene Keller, Christopher Beachy

Terrestrial salamanders function as dominant predators in forest floor communities because of their large population densities and voracious appetites. The impact they have on the community structure of their prey (leaf litter invertebrates) is appreciable. I will investigate these relationships in a bottomland hardwood forest where Plethodon mississippi is the prevailing salamander species. I will accomplish this by conducting an unrestricted field experiment using coverboard arrays and leaf litter collection. Three types of coverboard plots will be utilized: control, removal, and addition, where the salamanders found under boards in the removal plots will be taken out and put in the addition plots. Leaf litter samples will be collected from each plot monthly. Invertebrates will then be extracted using a Berlese funnel trap and identified to examine how their community structure changes when different densities of salamanders are present.

Hailey McGovern, Jonathan Akin

Antibiotic pollution in aquatic environments has become prevalent due to rising global consumption rates and widespread discharge from multiple sources. Ciprofloxacin, a fluroquinolone antibiotic, has been detected at high concentrations in surface waters and effluents, posing concerns about potential increases in mortality and developmental abnormalities in aquatic organisms. To assess the occurrence of these risks, a fish embryo toxicity test (FET) was conducted using zebrafish, a model organism. Newly fertilized embryos (>300) were exposed to environmentally relevant ciprofloxacin concentrations (0, 1, 12.5, 25, 50, and 100 µg/L) with distilled water serving as a control (i.e., 0 µg/L). Twenty embryos per concentration condition were sorted and selected for incubation in 24-well plates (one embryo per well) within semi-static systems, amounting to 120 embryos for analysis. Lethal and sublethal endpoints were recorded at 24-hour intervals throughout the 96-hour exposure period. While ciprofloxacin exposure did not significantly increase mortality or malformations across the tested concentrations, elevated heart rates and reduced movement were observed under the 50 µg/L exposure. These sublethal effects may indicate lower organismal fitness, which could negatively affect the sustainability of aquatic populations. Future studies aim to assess chronic exposure effects and LC50/EC50 values of ciprofloxacin on aquatic organisms.

Emma Alleman, Camrynn Sonnier, Jaeger Ebarb, Cynthia Doffitt

Ribeiroia ondatrae is a parasitic trematode that infects many hosts, including amphibians. Ribeiroia causes limb malformations in frogs.  In May 2024, American bullfrog (Lithobates catesbeianus) tadpoles (n=142) were collected from Natchitoches National Fish Hatchery (Natchitoches, LA). Tadpoles were humanely euthanized with a 1% MS-222 solution followed by decapitation. Tadpoles were dissected and metacercariae (juvenile trematodes) were found in the tail, dorsal fin, and hindlimbs. Parasites were excised, enumerated, and preserved in 70% ethanol. Of the 142 tadpoles, 29 (20.42%) were infected. In total, 97 metacercariae were recovered, with a mean parasite abundance of 0.68 (97/142) and mean parasite intensity of 3.34 (97/29). Recovered parasites will be identified based on their morphology using a carmine staining procedure and genomic DNA analysis. DNA was isolated and amplified using touchdown PCR with general platyhelminthes primers used to identify trematodes and conventional PCR with R. ondatrae-specific primers. PCR products were visualized with gel electrophoresis. Amplified DNA fragments were observed with both the general platyhelminthes and R. ondatrae-specific primers, suggesting the presence of Ribeiroia ondatrae in Northwest Louisiana. DNA samples will be sequenced to confirm the identity of the parasites. Future research will aim to identify the infection rate in frogs and the effects this parasite has on the American bullfrog populations.