Abbey Johnson, Enmin Zou

Crab exoskeleton is a bioconcrete consisting of an organic matrix (“steel rod network”) that is embedded in carbonate salts (“cement”), predominantly calcium carbonate. This carbonate salts-based exoskeleton is potentially adversely impacted by CO2 enrichment in seawater. A recent study has found that exposure of soft-shell blue crabs, Callinectes sapidus, to CO2- acidified seawater for 7 days can make crab shells sturdier, which is at least partly accounted for by increased mineralization. However, the post molt mineralization lasts for about two weeks in blue crabs. As such, a long-term exposure study is warranted. This study seeks to examine the effects that CO2-driven acidification has on the exoskeleton of Callinectes sapidus after prolonged exposure of soft-shell crabs to CO2-acidified seawater for 14 days. Two groups of soft shell blue crabs each were exposed to control seawater at pH 8.2 and CO2-enriched seawater at pH 7.8, respectively, for 14 days. At the end of exposure, carapaces of all the survivors were harvested, and calcium and magnesium content will be analyzed for both control and CO2-treated groups. Allowing the crabs to endure acidic exposure for a longer duration could reveal a limit to the amount of mineralization that can occur and determine what happens after this said limit is reached. The findings of this study can help further understand how exactly ocean acidification is impacting blue crabs, as ocean acidification is an ongoing, worldwide issue.

Abby Klahs

Salamander larvae possess the unique ability to adapt the shape of their gills in response to changes in water conditions. The external gills of salamander larvae are responsible for facilitating gas exchange and oxygenation, and a larger surface increases this process. Therefore, it is important to study the changes in their gills not only in different water conditions, but also across their larval development. To explore the degree of plasticity in gill structure, we collected Eurycea cirrigera larvae from Louisiana streams and, using a novel method, photographed their gills from an anterior and dorsal perspective. We hypothesize that smaller larvae will have a smaller proportion of gill to snout-vent-length (SVL) compared to larger larvae. The larger individuals have a smaller surface area to volume ratio, which decreases the efficiency of oxygen exchange. In order to compensate for their growing body size, it is also necessary to allocate energy towards growing their gills to increase respiration. We also hypothesize that larger larvae will have more complex gill structures than smaller larvae to increase the surface area of the respiratory organ.

Mikaela Spell, Sarah Baker, Mark Merchant, Cody Lafleur

Anecdotal evidence suggested that Chelodina timorensis turtles could alter their skin color when exposed to different light conditions. These turtles, also called Roti Island snake-necked turtles, are native to eastern Timor, Indonesia where they inhabit marshes and swamp-like habitats. The objective of this study was to determine if this species were capable of such ability. Twenty captive-bred hatchlings from Florida were raised in black tanks for several weeks. On week 8, half of the hatchlings were transferred to a white tank and placed under a lamp for constant light exposure, while the other half remained in the blank tanks. A colorimeter was used to measure skin color using a gray scale. This measurement of light and growth monitoring was conducted once a week. After the skin color of the turtles stabilized (13 weeks), the tanks were switched to determine if the changing color in response to light exposure and that the effect is reversible once the light exposure is lowered. This study can provide insight to how these turtles interact with their environment, as well as what type of wavelengths this species can respond to.

Florence Wen, Oliver Ljustina, Brandon Hedrick

Like most vertebrate species, reptiles typically respond poorly to urbanization. Species that persist in urban environments are subjected to a variety of potential stressors, including pollutants, exotic predators, road mortality, inadequate nutrition, among others. However, negative impacts may be offset by factors such as resource subsidies and a decrease in native predators. While many turtle species occur in urbanized areas throughout the southeastern United States, negative impacts on individuals and populations may be obscured by their relatively long lifespans. We hypothesized that individuals from an urban population of Eastern Musk Turtle (Sternotherus odoratus) in Kenner, Louisiana would exhibit greater signs of stress and decreased body condition compared to those from a population found in a natural, non-urbanized area. To assess stress, we examined their body condition, heterophil: lymphocyte (H:L) ratios, and fluctuating asymmetry. Contrary to our hypothesis, we found that urban turtles were significantly heavier and larger, but showed no difference in body condition to turtles from the natural site. In addition, our urban turtles had higher H:L ratios and shell asymmetry, suggesting they were more chronically stressed. These results suggest that environmental factors other than lack of foraging opportunity act as stressors of turtles found in urban areas, and that even populations that appear to thrive in urban areas may be at risk of decline.

Amber Hale

The McNeese Bee Program currently houses 14 honeybee colonies at the McNeese Farm. Ten well-established colonies were sampled for genetic analysis via whole genome sequencing. Pending analysis, unique features that have been well-characterized genetically will be reported. McNeese harvests honey every Fall from healthy hives. We conducted a pollen analysis using Next Generation Sequencing. The plants that the bees visited in order to produce honey will be identified to the species level. This information gives us spatial and temporal information regarding the bees’ range and productivity. Finally, we screened the honey for chemical and pesticide residues. Since the McNeese farm borders significant farmland as well as more urban landscapes, we were interested to determine if we could detect glyphosate (and glyphosate analytes; Glyphosate, Glufosinate-ammonium, AMPA) in the honey product.

Harry Meyer, Kathy Jackson

Tardigrades (water bears) are minute arthropod relatives found in mosses, lichens, and soil. Their adaptation to small size means that there are relatively few useful reliable morphological/morphometric characters available for species delineation. With the advent of molecular techniques, what was deemed to be a single species, with cosmopolitan or continental distribution, has often turned out to be a conglomerate of related taxa. Claxtonia mauccii was described in 1956 from moss collected in Wisconsin near the Michigan border. It has since been widely reported in Canada, the continental United States, and Hawaii. Using both light microscopy and molecular techniques, we examined specimens from the type locality, southwestern Virginia, northeastern Tennessee, and Hawaii. Specimens from the various sites could not be distinguished morphologically or morphometrically. COI p-distances between the type locality and Tennessee (0.011-0.071) indicate that the Tennessee population is Cla. mauccii sensu stricto. However, p-distance between the type locality and Virginia (0.201) makes it clear that the Virginia specimens are a different, undescribed cryptic species. The Virginia and Tennessee sites are both mountainous and about 200 km apart. Claxtonia from Hawaii were the same species as Virginia (0.008-0.013). Molecular analysis of putative Cla. mauccii populations in California and Washington is underway.