2022 Spring Student Research Symposium Posters

Permanent URI for this collectionhttps://hdl.handle.net/1969.6/90411

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Physical properties of dicarboxylated amino acid based surfactants in presence of diamine alkane counterions
(2022-04) Fritz, Shayden; Billiot, Eugene; Billiot, Feri; Olson, Mark
Surfactants are being examined for many different fields such as chemical, medical, cosmetics, and phar- maceutical applications. Surfactants consist of two regions a hydrophobic and a hydrophilic region. The hydrophobic region is the head in most surfactants, while the hydrophilic region is the tail. Surfactants are dynamic molecules and able to form micelles. The micelles form when the hydrophobic region aggregates together and forms different shapes. The concentration at which micelles are formed is called the critical micelle concentration (CMC). The CMC is the lowest concentration needed for the surfactants to form mi- celles. Many different types of surfactants can be created. The surfactants that were examined consisted of dicarboxylated amino acid groups (glutamic and aspartic) with a 11 and 13 caron chain hydrophobic tails. The CMC of these surfactants were measured in presence of 1,2 diamino ethyl, 1,3 diaminopropane, 1,4 diaminobutane, 1,5 diaminopentane and 1.6 diaminohexane. The effects of the different amino acids, tail structures, and counterions were tested by comparing the CMC values of the solution. The CMC was measured using the change in solution conductivity at different surfactant concentrations. Preliminary re- sults indicated that the hydrophobic chain length and the counterion type significantly effects aggregation behavior of the dicarboxylated amino acid surfactants in solution.
Impact of ocean acidification on montipora capitata growth
(2022-04) TenBrink, Eleanor; Tripler, Abigail; McNicholl, Conall; Bahr, Keisha D.
In Kāne’ohe Bay Hawai’i, the second most dominant coral species, Montipora capitata is an ecologically important reef building coral that has shown to be resilient to environmental changes. However, ocean acidification may compromise the structural integrity of the coral’s skeleton threatening the species’ resiliency. Therefore, this project will analyze various biological response variables of M. capitata under the stress of ocean acidification (OA). OA is a change in ocean water chemistry due to an increase in atmospheric carbon absorption, which decreases the pH and aragonite saturation state. This also increases the amount of hydrogen ions in the water, which will impact the total alkalinity, or the ability of the water to neutralize ions. Previous research has stated that a lower aragonite saturation state negatively impacts the coral’s ability to calcify under OA conditions. Contrarily, the Proton Flux Hypothesis states that the increase in hydrogen ions limits coral calcification under OA. To better understand coral growth under OA conditions, corals were exposed to a control and 3 experimental treatments varying in pH and total alkalinity levels, over a month-long experiment. Following experimentation, individual biological response variables from each coral will be measured. These variables include the concentrations of chlorophyll and symbiodinium, along with the protein content and changes in the skeletal density of the coral host. It is hypothesized that the combination of low pH and total alkalinity will have a synergistic effect on the coral’s skeletal density. However, the symbiodinium and chlorophyll will experience an antagonistic effect from the changes in water chemistry. The result of this work aims to determine the driving forces behind the dissolution of coral skeletons under OA conditions in order to support the Proton Flux Hypothesis.
Native vs. Invasive community interactions: Snail herbivory in Louisiana and Mato Grosso (Brazil) wetlands
(2022-04) Stratford, Juliana; Battaglia, Loretta
Pomacea maculata is the largest freshwater snail in the world. This native of Brazil was introduced to the southeastern United States in 1989. A documented voracious consumer, it continues to spread and threaten wetlands in this region, where it happens to overlap with two highly invasive aquatic macrophytes that also hail from Brazil: Salvinia minima and Eichhornia crassipes. This invasive community poses a great threat to native wetland ecosystem structure and function, but also presents a unique opportunity to examine multi- species interactions with shared evolutionary histories. The primary objectives of this study are threefold:1) to determine whether P. maculata diet reflects a preference for native Louisiana macrophytes over the co-evolved invasive plants; 2) to determine whether P. maculata can be a viable biocontrol agent for S. minima and E. crassipes in their invaded range; and 3) to compare P. maculata herbivory in its invaded and native range. Project objectives will be addressed through a series of controlled feeding trials using snails and plants from local populations in Louisiana and Mato Grosso (Brazil).
Characterization of limpet shells using 3D scans
(2022-04) Villarreal, Amanda; Romano, Julie; Cockett, Patricia; Mehrubeoglu, Mehrube
Limpets are bioindicators of their environment as their growth patterns and physical attributes are related to the conditions in their surroundings. Limpet shell attributes, such as shell volume, length, height, width and thickness, provide an indication of the limpet’s environmental conditions, as the animal spends its resources accordingly to either grow and/or to strengthen its shell, or how the shell is weathered. This research focuses on determining the physical attributes of limpet shells obtained from Hawaii to provide an accurate tool for scientists to compare different shell characteristics within and across multiple shell locations. Multiple physical measures are captured through 3D scanning data and computations through the MATLAB programming tool. These measurements include inner shell volume, outer shell volume, solid shell volume, major axis, minor axis, height, peak shift, and surface area. The 3D measurements are compared to physical measurements, when feasible. For example, solid shell volume is measured using water displacement method. Major and minor axes as well as height are also measured with a ruler for comparison. The characteristics of the shells collected from two different locations, one from Makalawena and the other from Puanwi are presented. The listed physical attributes of the limpet shells are analyzed to establish correlations between the region where the animal grows and the shell characteristics themselves. The focus of this presentation is the development of the engineering tool that is capable of 3D measurements with high accuracy to achieve the scientific goals of the project.
Bottlenose dolphin (tursiops truncatus) spatial dispersion and orientation in pods
(2022-04) Partin, Caitlynn; Orbach, Dara N.; Ramos, Eric Angel; Magnasco, Marcelo O.; Reiss, Diana
Bottlenose Dolphins (Tursiops truncatus) are commonly found in the waters of Turneffe Atoll, Belize, where they inhabit areas that vary in physical features. Variables such as water depth, prey abundance, and location are related to the spatial dispersion of bottlenose dolphins. The spatial dispersion (areas within a pod) and orientation (line abreast, parallel, scattered, facing inward) of bottlenose dolphin pods have yet to be examined in relation to pod size, substrate type, and behavioral state. We explore how abiotic and biotic factors may affect bottlenose dolphin movement. Video recordings of free-swimming bottlenose dolphins were taken by drone in Turneffe Atoll, Belize and transformed into a series of screenshots for data extraction. Pod size (3-15), substrate type (boundary, seagrass, mixed), and behavioral state (forage, social, rest, travel) were categorized from the screenshots. Spatial dispersion and orientation were measured in ImageJ and data were averaged per video. Spatial dispersion of dolphin pods was significantly related to pod size, substrate type, and behavioral state (F = 3.375, P < 0.05). Pods were most dispersed when engaged in social activities, suggesting frequent events of separation. When swimming over a mixed substrate, spatial dispersion was also high, potentially indicating a lack of predators or an abundance of non-schooling prey. Small pods (n < 15) showed low spatial dispersion, suggesting a potential defensive strategy against predators. Assessment of dolphin activity researched using non-invasive techniques yield insights to how dolphins use their habitat when exposed to minimal human encroachment.
Oysters holding their breath: Comparing methodology for measuring the physiological response of Crassostrea virginica
(2022-04) Gomez-Rangel, Kate D.; Good, Alexandra; Matt, Joseph; Hollenbeck, Christopher; Bahr, Keisha
In Texas, the Eastern Oyster, Crassostrea virginica, is an ecologically and economically valuable benthic organism and has been shown to adapt to a variety of environmental changes. However, measuring oyster physiology has proven diﬀicult due to the oyster’s response of closing their shell for long periods of time as a defense mechanism. Therefore, this project aims to test various methods of measuring oxygen consumption rates to determine oyster tolerance thresholds under changing environmental conditions to inform place- based management of oyster farming and restoration. This project will test two methods, the procedure of notching the oyster with a Dremel and a blocking procedure that uses a plastic wedge to prevent the oyster valves from closing shut completely. However, with both these procedures, there is the potential of the oysters becoming stressed which could alter their physiological response during experimentation. Therefore, these techniques will be compared to help researchers understand the impact of additional stress when conducting physiological measurements, with the goal of successfully opening the valves of the oysters to measure oxygen consumption rates over set periods of time. The results of this work will assist in retrieving data on dissolved oxygen consumption rates and oyster shell calcification when exposed to multiple, interacting stressors (i.e., salinity and temperature). Understanding the oyster’s organismal response and tolerance threshold to changing environmental conditions will provide data that supports policy and management of Texas oyster ecosystems.
Impact of ocean acidification on montipora capitata growth
(2022-04) TenBrink, Eleanor; Tripler, Abigail; McNicholl, Conall; Bahr, Keisha
In Kāne’ohe Bay Hawai’i, the second most dominant coral species, Montipora capitata is an ecologically important reef building coral that has shown to be resilient to environmental changes. However, ocean acidification may compromise the structural integrity of the coral’s skeleton threatening the species’ resiliency. Therefore, this project will analyze various biological response variables of M. capitata under the stress of ocean acidification (OA). OA is a change in ocean water chemistry due to an increase in atmospheric carbon absorption, which decreases the pH and aragonite saturation state. This also increases the amount of hydrogen ions in the water, which will impact the total alkalinity, or the ability of the water to neutralize ions. Previous research has stated that a lower aragonite saturation state negatively impacts the coral’s ability to calcify under OA conditions. Contrarily, the Proton Flux Hypothesis states that the increase in hydrogen ions limits coral calcification under OA. To better understand coral growth under OA conditions, corals were exposed to a control and 3 experimental treatments varying in pH and total alkalinity levels, over a month-long experiment. Following experimentation, individual biological response variables from each coral will be measured. These variables include the concentrations of chlorophyll and symbiodinium, along with the protein content and changes in the skeletal density of the coral host. It is hypothesized that the combination of low pH and total alkalinity will have a synergistic effect on the coral’s skeletal density. However, the symbiodinium and chlorophyll will experience an antagonistic effect from the changes in water chemistry. The result of this work aims to determine the driving forces behind the dissolution of coral skeletons under OA conditions in order to support the Proton Flux Hypothesis.
Sulfide intrusion in the seagrass Halodule wrightii as assessed by tissue sulfur isotopic composition
(2022-04) Girard, Allyson; Larkin, Patrick
Seagrass populations are declining considerably due to anthropogenic pressures, such as nutrient loading into coastal waters. Excessive nutrient availability in these environments can induce eutrophication events that ultimately generate anoxia in marine sediments. This promotes the activity of anaerobic sulfate-reducing bacteria, which reduce sulfate (SO42-) to hydrogen sulfide (H2S) for energy production. When high levels of this bacterial activity persist, H2S accumulates in the sediment. This small molecule can be highly toxic to living cells; yet, seagrasses appear to withstand relatively high concentrations of H2S in their environments. The purpose of this study is to assess sulfide intrusion in the seagrass Halodule wrightii from various locations along the Texas Gulf Coast, and determine whether the uptake and distribution of sulfide-derived sulfur in H. wrightii vegetation differs between locations. Vegetation, sediment, and seawater samples were collected from three H. wrightii meadows within two estuaries near Corpus Christi, TX: two from the Upper Laguna Madre and one from Oso Bay. Root, rhizome, and leaf tissue from vegetation samples were separated, lyophilized, and homogenized into a fine powder. Sediment samples underwent a distillation procedure capable of liberating H2S gas, which was precipitated as Ag2S. Seawater samples were acidified and treated with BaCl2 to precipitate seawater sulfate as BaSO4. Tissue, Ag2S, and BaSO4 samples were analyzed for their sulfur stable isotopic composition by EA-IRMS. 34S values of H. wrightii samples taken from the Upper Laguna Madre, for all tissue types, were lower than those obtained for vegetation from Oso Bay, suggesting that the Upper Laguna Madre populations sourced more sulfur from sedimentary sulfide compared to the Oso Bay population. Results interpreted to date suggest a difference between H. wrightii populations from these two locations in sulfide uptake and assimilation, and allows for future research into the effects of local conditions on seagrass sulfur metabolism.
Changes in seagrass genotypic diversity over a four-year time span
(2022-04) Larkin, Abigail; Larkin, Patrick
The seagrass Halodule wrightii is a vital part of Texas Gulf Coast ecosystems. Genetic diversity is associated with many positive traits, and a decrease could result in a decline in the viability of the overall plant population. We examined genotypic diversity (R) in a population of Halodule wrightii from Oso Bay, Tx, and compared the results to those collected in 2017 and 2019 from the same location. Past results indicated low to moderate genotypic diversity in this population and a lack of an evident seed bank. In 2021, we were only able to collect samples from 25 out of 48 positions, representing a 49% loss of seagrass coverage since 2019. We found that, over this time period, 11 genotypes were lost, and 9 new genotypes were gained. The genotypic diversity estimate for 2021 (R = 0.25) was similar to that of 2017 and 2019 (0.22 and 0.24, respectively). Our results indicate that Halodule wrightii is able to maintain genotypic diversity over time, despite a significant decline in population size and lack of an evident seedbank.
Analysis of coastal spatial-temporal systems of two species competition: Impact of the parameters of the system on species survival
(2022-04) Wang, Youwen; Vasilyeva, Maria; Stepanov, Sergei; Sadovski, Alexey L
This presentation deals with the spatial-temporal dynamical models of two-species competition in 1D and 2D spaces. We have applied factor analysis to the results of tens of thousands of simulations with different combinations of parameters and initial conditions. Firstly, we have found that initial populations, if they are not too small, don’t affect equilibriums. Secondly, we have discovered that the diffusion rate has an impact on whether one or both species survives. Thirdly, the ratios of birthrates to competition parameters play significant role in which of two species survives.
Cryptic corals: Coral polyp size and biometry are indicators of feeding mechanisms
(2022-04) Gates, Maryssa; Epps, Ashleigh M.; Bahr, Keisha
Reef-building coral species are found in relatively stable environments with specific environmental conditions such as water temperatures ranging from 25◦C-29◦C. However, two cryptic coral species (non-reef building), Astrangia poculata, and Oculina diffusa were recently documented in a shipping channel in Corpus Christi, TX. However, there is little information regarding these coral colonies in Corpus Christi, TX. Therefore, this study aims to investigate the primary feeding mechanism of the cryptic coral species to understand the survival strategies. To do this polyp sizes and abundance were compared per colony, seasonally over a 100-meter transect. Coral colony samples were collected from Packery Channel, Texas seasonally over a year, and each of the polyps was counted and sized for area. Polyps were significantly smaller during the Fall season compared to the Winter colonies. The change in the average polyp size over the year suggests that these corals adjust their feeding mechanisms in response to their fluctuating environmental conditions. In addition, there was also a significant difference in the mean area of the polyps between the two locations of the colonies on the shipping channel (bay side or gulf side), with the bay side being larger overall. The significantly larger size of the bay side suggests that cryptic coral species adjust their feeding mechanisms based on location within the shipping channel. These findings provide insight into how the cryptic coral species survive in the dynamic conditions present in Corpus Christi, TX.
The effect of thermal stress and nutrient loading on the coral – algal symbiosis in a dominant Hawaiian reef coral
(2022-04) Blesa, Victoria; Ruben, Zoe; Rueda, Ignacio; Bahr, Keisha D.
Coral reefs are one of the most biodiverse and valuable ecosystems on the planet, and healthy reef systems can sustain a multitude of marine species, defend coastlines from storm surges, and provide employment for people in local communities. The health and prosperity of reef-building corals is largely attributed to the partnership with their algal symbiont, zooxanthellae. A large body of research contributes to understanding how corals and zooxanthellae respond to individual stressors. However, fewer articles clarify how multiple interacting stressors may threaten these ecosystems and disturb corals’ relationship with zooxanthellae. Therefore, this research aims to quantify changes in zooxanthellae density in corals that have been subjected to the interactive effects of thermal stress and nutrient loading. Corals were collected from two sites in Kāne ohe Bay, Hawai i, encompassing a gradient of temperature and nutrient influence. For one month, corals were subjected to four experimental treatments (Control, Heated, Nutrient, Heated + Nutrient). Fragments were collected at the beginning and end of the experiment, flash frozen in liquid nitrogen, and shipped back to TAMU-CC for subsequent analysis. Coral experimentation began with airbrushing the coral tissue to remove it from the skeleton, yielding tissue slurry used for the biological assay. The organic matter was lysed using a tissue homogenizer and then centrifuged to create coral pellets. The biological pellets were then resuspended in the phosphate-buffered saline (PBS) and vortexed to create an aliquoted subsample which could then be counted under a microscope using a hemocytometer. Upon analyzing the experimental results, it is hypothesized that the corals that underwent the Heated + Nutrient treatment may be more susceptible to bleaching due to the combined stressors. This study will aid our understanding of how corals in Kāne ohe Bay respond physically to interacting stressors
Understanding the motivating factors and collegiate experiences of international non-stem students
(2022-04) Salunke, Vedika S.; Bazner, Kevin J.
The scale of movement of international students has increased dramatically since the 1950s, with the U.S. acting as a major destination owing to a good education system and generous funding of graduate studies (Alberts & Hazen, 2005). International students are not only a valuable financial asset to the host country, but they also enrich these host countries by their cultural and diverse backgrounds. International students also offer skilled, intellectual labor to the workforce with a wide range of knowledge across disciplines. According to Adhikari (2017), the number of international students in the United States is helping fill that demand but there is likely to be a push for more domestic students to enter the STEM field. There is also likely to be a shift in the reasons of students pursuing STEM fields because of the push to engage students in STEM fields earlier in their academic careers. This increase has led to more focus by researchers and institutions on STEM students, leaving out non-STEM students and their needs, experiences, and challenges. The purpose of this study is to understand the motivating factors and campus experiences of international students enrolled in non-STEM degree programs. Based on data collected from six participants in semi-structured interviews, the study explores: (1) Motivations of international students to enroll in a non-STEM program; (2) Their understanding of the OPT policies for STEM and non-STEM degree programs; (3) Academic challenges and college experiences of international non-STEM students. Limited support from recruiting agencies in the university’s application process, unawareness of STEM/ non-STEM differentiation and OPT policies, limited funding opportunities were the key findings of this study. Implications for this research will aid institutional leaders in better understanding the campus experiences of non-STEM international students and provide opportunities for improvements to student recruitment, campus programming, and academic support initiatives.
Numerical solution of the spatial-temporal model of population distribution in heterogeneous domain
(2022-04) Henry, Stephen; Vasilyeva, Maria; Sadovski, Alexey L
In this work we consider temporal-spatial models of one species population distribution in heterogeneous domain. Mathematical models of such problems are described by a nonlinear parabolic equation in the two- dimensional domain D: 𝜕𝑢/𝜕t −∇ (𝜀 (x) ∇ u) = 𝑟(x) (1 − 𝑢) 𝑢, x ∈ 𝐷, where u is the function of 2D coordinates x and time t, r is the rate of reproduction and is the diffusion. This equation has certain initial and boundary conditions pending on the specifics of the problem. Here we have used a finite element method to solve this problem in the complex geometry with heterogeneous inclusions and implicit-explicit time approximation. Numerical implementation is performed by using python and finite-element library FEniCS. We have done numerical investigation of the influence of the geometry and heterogeneous properties on the solution.
The influence of diamine counterion use and surfactant counterion ratio on chiral selectivity of amino acid-based surfactants
(2022-04) Montoya, Sara; Black, Nathan; Billiot, Eugene; Billiot, Fereshteh; Morris, Kevin
In this study, the effects of counterion type and surfactant-to-counterion ratio on the chiral selectivity of several binaphthyl derivatives with L,L- undecanoyl leucine-valinate was examined by use of Micellar Electrokinetic Chromatography (MEKC). The chiral separations of 1, 1−𝑏𝑖−2−𝑛𝑎𝑝ℎ𝑡ℎ𝑦𝑙−2, 2−𝑑𝑖𝑦𝑙ℎ𝑦𝑑𝑟𝑜𝑔𝑒𝑛(𝐵𝑁 𝑃 )1, 1′−𝑏𝑖−2−𝑛𝑎𝑝ℎ𝑡ℎ𝑦𝑙−2, 2′−𝑑𝑖𝑎𝑚𝑖𝑛𝑒(𝐵𝑁𝐴)𝑎𝑛𝑑1, 1′−𝑏𝑖−2−𝑛𝑎𝑝ℎ𝑡ℎ𝑜𝑙(𝐵𝑂𝐻 by the dipeptide surfactant varied widely in the presence of three counterions, 1,2 diaminoethyl, 1,2 diamino- propyl, and 1,3 diaminopropyl and with surfactant-to-counterion ratios of 1-to-1 and 1-to-0.5. The results of this study have shown that the selection of 1,2 diaminoethyl in a 1-to-1 surfactant-counterion-ratio provides enhanced baseline separation for enantiomers of BOH in comparison to its 1-to-0.5 counterpart, though no significant difference in separation can be observed for enantiomers of BNP under the same conditions. Despite the observation that every one of the three included counterions engendered some degree of separation for each analyte, enantiomers of BNP exhibited heightened separation in the presence of 1,2 diaminoethyl and 1,2 diaminopropyl at a pH level of 8. Conversely, the comparative Na counterion separates enantiomers of BOH and BNA significantly better than the counterions examined.
Whole genome amplification decreases the quality of whole genome sequencing for century old ETOH preserved fishes
(2022-04) Roberts, Roy; Garcia, Eric; Bird, Christopher E.
The genomes of organisms stored in museums hold a wealth of information that is challenging to sequence. Recent success in sequencing desiccated museum insects involved using whole genome amplification (WGA) and enzymatic repair (NEBNext FFPE Repair Mix) of DNA damage, but these techniques have not been tested on fishes. The Smithsonian Museum currently hosts one of the largest single collections of fishes which was conducted over a century ago on board the RV Albatross and consists of over 27,000 jars, or ‘lots‘, of marine fishes from the Philippines alone, and all were preserved in rum distillates and stored in 70% EtOH which should enable DNA sequencing. Here, we use factorial treatment combinations to test for the effects of WGA, enzymatic repair, and amount of DNA input on whole genome shotgun sequencing of RV Albatross and contemporary samples (preserved in 95% EtOH) of three species of Philippine marine fishes. A total of 74 libraries (30 WGA, 44 NoWGA) were sequenced (2 x 150bp) using one individual per era and species when possible. After adapter trimming, quality filtering, and removal of contaminant sequence reads, contemporary libraries were assembled de novo, and all libraries were mapped to the longest 100 contigs from the best genome assembly of each species according to n50 and BUSCO analysis. Contrary to expectation, WGA had a negative effect on depth of coverage and number of informative positions for historical libraries (p < 0.05). For both contemporary and historical libraries, neither enzymatic repair nor DNA concentration had a consistent effect on number of SNPs or depth of coverage (p > 0.05). Overall, we were able to successfully recover enough DNA to meaningfully test for differences between contemporary and historical libraries and perform downstream population genomic analyses, using a standard shotgun library preparation protocol and $75 of sequencing per library.
Requirement of gene transcription for experience-dependent long-term plasticity in the feeding neural circuit of an invertebrate model
(2022-04) Mueller, Robert; Wainwright, Marcy; Mozzachiodi, Riccardo
Long-term memory formation is known to generally require gene transcription (Kandel 2001). Previous research within the marine mollusk Aplysia revealed that repeated exposure to aversive stimuli induces a lasting enhancement of defensive responses, known as long-term sensitization (LTS). LTS is mediated, at least in part, by long-term increased excitability (LTIE) of sensory neurons (SN), which is known to depend on gene transcription (Byrne and Hawkins 2015). Repeated exposure to aversive stimuli also induces long- term feeding suppression (LTFS) via a long-term decreased excitability (LTDE) of decision-making neuron B51 (Shields-Johnson et al. 2013). However, it is unknown whether B51 LTDE depends on transcription processes like those in the defensive circuits. Therefore, this study examines the molecular requirements for LTFS by determining whether B51 LTDE is transcription dependent. Actinomycin D (ACT-D) is being used to selectively inhibit gene transcription (Montarolo et al. 1986). This project utilizes a previously established in vitro preparation that includes the neural circuits responsible for LTS and LTFS. Electrical stimulation of afferent nerves from the body wall to mimic aversive training in vitro co-induces SN LTIE and B51 LTDE lasting 24 h (Weisz et al. 2017). Ongoing experiments utilize 4 groups: trained/vehicle, trained/ACT-D, untrained/vehicle, and untrained/ACT-D (Weisz et al. 2017). Statistical analysis is being conducted using the Kruskal-Wallis test (Farruggella et al. 2019). Current results indicate that ACT-D is effective in blocking the expression of SN LTIE, as previously shown (Montarolo et al. 1986). Regarding B51, although overall statistical significance across groups has not been reached yet, current findings show a trend that LTDE expressed in the trained/vehicle group is blocked in the trained/ACT-D group. If these results are confirmed statistically, they will demonstrate that ACT-D inhibits B51 LTDE, thus indicating that B51 LTDE requires transcription processes for long-term memory formation analogous to SN LTIE in the defensive circuits.
A feed-forward neural network framework for the solution of linear and nonlinear ordinary differential equations
(2022-04) Venkatachalapathy, Pavithra; Muddamallappa, Mallikarjunaiah
Differential equations (DEs) play a key role in modeling the physical, chemical, and biological processes. Virtually every phenomenon occurring in nature can be described by an equation with dependent variable(s), more than one in some instances, and an independent variable(s). Only in some special circumstances, the DEs are tractable to certain well-known analytical techniques. In other instances, the solutions are approximated by prominent collocation methods such as finite elements, finite differences, finite volume techniques etc. Unfortunately, for certain Boundary Value Problems (BVPs) devising a proper approximation method is both challenging and diﬀicult. In this work, we study a feed-forward multilayer perceptron Artificial Neural Network (ANN) framework to approximate the solution to varieties of two-point BVPs. The trail solution is the sum of two parts: the first part satisfies the boundary conditions while the second approximates the solution which is obtained by the inputs to the number of hidden layers. The mean-squared loss function is minimized by a class of gradient descent optimization methods to obtain the desired output. Our plan is to employ the proposed deep-learning architecture to a variety of DEs and report the convergence of the ANN output.
Drifting between two worlds: identifying plankton diversity and abundance in packery channel, Texas
(2022-04) Bruce, Morgan N.; Epps, Ashleigh; Bahr, Keisha D.
Packery Channel is a eutrophic environment in a small jetty system that allows plankton migration between Corpus Christi Bay and the Gulf of Mexico. Plankton are marine organisms that play a critical role as primary food sources for many animals, such as corals. Recently, corals have been found surviving in the dynamic conditions of Packery Channel. However, there has been limited research conducted on plankton abundance and diversity due the channel recently reopening. Therefore, this project aims to identify and quantify the abundance of plankton present in Packery Channel by collecting samples at various tides during the full moon cycle over a year-long period. Plankton nets were towed (phytoplankton = 63 m and zooplankton = 243 m) along a 50-meter transect alternating between the North and South sides of Packery Channel to encompass the whole channel. It is hypothesized that the highest abundance will occur during summer and night periods and the lowest abundance will occur during winter and daytime periods. This is due to the difference in light availability, tide flow, and temperature which has been found to make an impact on plankton. Results from this study indicate the corals within Packery Channel potentially have resources available when under stressful conditions such as limited sunlight. Understanding the seasonal dynamics of plankton within Packery Channel is necessary to expand research within estuarine systems and aid in understanding how corals survive in extreme conditions.
Post-disturbance differences in litter decomposition and macroinvertebrate communities in a Texas saltmarsh-mangrove ecotone
(2022-04) McGuigan, Molly; Proﬀitt, C. Edward; Devlin, Donna J.
As a result of climate change induced stressors, such as changing weather patterns and frequency and intensity of disturbance, many ecosystems are experiencing regime shifts. Coastal saltmarshes along parts of the Gulf of Mexico are being encroached upon and associated plant species are outcompeted as populations of Avicennia germinans (L) L, the black mangrove, expand due to a decrease in freeze events. This study has two main goals: to investigate the difference in macroinvertebrate community composition, diversity, richness, and abundance in litter habitat between two dominant vascular plant species – the marsh forb Batis maritima L and the mangrove A. germinans – across a temperature and salinity gradient, and to investigate the effect of macroinvertebrate colonization on litter decomposition rates across a temperature and salinity gradient. We also aim to determine individual species that are key contributors to litter decomposition. We hypothesize that community composition, diversity, richness, and abundance will vary among litter type and sites, with the greatest difference between sites at each end of a thermal gradient. Additionally, we hypothesize that macroinvertebrate colonization will increase decomposition rates in high salinity areas. To test this, we will deploy mesh bags containing leaf and stem litter at multiple sites of varying temperatures and salinities along the Texas Gulf coast. Bags will be placed near the waters’ edge of the intertidal zone and will be retrieved at different time intervals and returned to the lab where litter dry mass loss will be determined, and macroinvertebrates sorted and identified to the lowest practicable taxonomic level. This study will take place from March 2022 – January 2023 and is significant due to the limited number of studies on shallow water macroinvertebrate communities in saltmarsh-mangrove ecotones as well as understanding the impact of regime shifts on macroinvertebrate communities

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