LONG ORAL PRESENTATIONS
Identifying marine ornamental teleost eggs and larvae based upon morphological characteristics
Jessie Castanier, John Scarpa, Andrew Fields, David Portnoy, Simon Geist
The aquarium trade is highly dependent on wild sources of marine reef fishes. Collection techniques for ornamental reef fishes can be damaging to reef ecosystems and over-exploitation threatens susceptible fish populations. Aquaculture of reef fishes can be an economic approach to conservation, minimizing individuals taken from the wild and unnecessary mortalities. While life history has been studied for a number of species, early-stage identification of eggs and larvae in mixed species tanks can contribute to a better understanding of species-specific life history and improved culture techniques. The aim of the present study is to identify eggs and early-stage larvae in the Living Coral Reef (LCR) exhibit at the Texas State Aquarium (TSA) based on morphological features and DNA barcoding of the mitochondrial cytochrome c oxidase 1 (CO1) gene region. The objectives are to determine if 1.) eggs of different species can be visually distinguished based on egg diameter, oil globule diameter, and pigmentation and 2.) if newly hatched larvae of different species can be distinguished on total length and pigmentation as verified with DNA barcodes. It is expected that eggs and larvae of different species will look different enough to distinguish at the species level. Successful collection and identification of eggs and larval fishes will be useful for determining and implementing specialized larval culture techniques of targeted species, contributing to a sustainable source of ornamental fishes at TSA.
Isotopic composition of nitrate and ammonium in Sao Paulo, Brazil wet deposition
Adrianna Chapa, J. David Felix, Lucia A. M. Campos
Humans have altered the nitrogen cycle by emitting excess reactive nitrogen into the atmosphere causing ammonia (NH3) and nitrogen oxides (NOx) concentrations in the atmosphere to increase exponentially over the last century. Excess nitrogen causes negative environmental and health effects by contributing to acid rain, decreased air quality, soil acidification, eutrophication, and a change in biodiversity. In order to better understand the nitrogen cycle, emission sources, and mitigation strategies, regional emissions of NH3 and NOx should be quantified. This study will measure the stable isotopic composition of nitrate (NO3-) and ammonium (NH4+) in wet deposition in order to estimate NH3 and NOx emission sources in the Ribeirao Preto region of Sao Paulo, Brazil. Wet deposition in the form of rain samples were collected after every rain event in Ribeirao Preto from October 2018 through February 2020. The δ18O-NO3-, δ15N-NO3-, and δ15N-NH4+ values from the sampling period ranged from 38.0‰ to 71.1‰, -10.6‰ to 13.1‰, and -19.8‰ to 14.6‰ respectively. The δ15N-NO3- and δ15N-NH4+ values in rainwater were corrected for fractionation processes and along with δ15N values of NOx and NH3 emission sources were applied to the Stable Isotope Analysis in R (SIAR) mixing model program to estimate source contributions. Results aid in understanding the emission sources affecting air quality in Sao Paulo, Brazil and provide information on the emission and transportation of NOx and NH3 in the environment.
Evaluating the relative habitat value of intertidal and subtidal oyster reefs to improve restoration methods
Devin Comba, Jennifer Beseres Pollack, Terry Palmer, Natasha Breaux
Historically, intertidal oyster reefs were spared from commercial harvest due to physical inaccessibility. Decreases in productivity of subtidal reefs lead oystermen to instead exploit intertidal reefs. To compare habitat value indicators between subtidal and intertidal habitats, macrofaunal communities, oyster recruitment and growth, and disease development in natural and restored areas were assessed. Results show significant macrofaunal community diversion between intertidal and subtidal habitats both on and around the reefs.
Evaluation of three marsh evolution models for the Northern Gulf of Mexico National Estuarine Research Reserves: Comparison of modeling approaches and available output
Diana C. Del Angel, David Yoskowitz
There is a growing concern about sea-level rise (SLR) and its potential impacts on coastal shoreline habitat, particularly intertidal marshes. Marshes could maintain their spatial extent under SLR, transition to other habitats, or submerge. Wetland transition models are essential to inform government communities before resources and time are invested in adaptation, mitigation, or restoration strategies. There are various modeling approaches for estuarine wetlands, and it can prove difficult for a non-technical audience to decipher the differences and usability of models. This study compares technical aspects and output of three prominent SLR transition models: the Sea Level Rise Affecting Marshes Model (SLAMM), the Hydrodynamic Marsh Equilibrium Model (Hydro-MEM), and NOAA-Marsh Migration Model (NOAA-MMM). The study site includes Apalachicola, Weeks, and Grand Bay NERRs.
This work highlights the considerable difference between the model outputs across the sites. A z-score was calculated to assess the models’ difference in the projected marsh area; these results show no consistent over-estimation or underestimation by a particular model. The Coefficient of Variation results show that the magnitude of the differences varies across sites. Overall, the differences in the output overlap are likely due to the heterogeneity of wetland habitats. Further, sites with significant river flow, such as Apalachicola and Weeks Bay, show more variability among the marsh projections.
Behavioral and cellular effects of serotonin on the memory deficits caused by food deprivation in the marine snail Aplysia
Xin Deng, Kourtlin Williams, Marcy Wainwright, Riccardo Mozzachiodi
Malnutrition causes brain dysfunctions including memory deficits. Challenges of studying food deprivation-induced memory deficits in mammals include mimicking starvation without health deterioration or nervous system damage. The marine snail Aplysia, which remains healthy for up to 14 days of food deprivation (14DFD), was selected for this study. In normally-fed Aplysia (animals fed every two days, 2DFD), exposure to aversive training induces a form of learned fear known as sensitization. Sensitization manifests as enhancement of defensive reflexes, including the tail-induced siphon withdrawal reflex (TSWR). In a reduced preparation consisting of the isolated nervous system, in vitro delivery of sensitization training increases the excitability of tail sensory neurons (TSNs) in the TSWR neural circuit. Following sensitization training, serotonin (5-HT) is released in neuropil and hemolymph. 5-HT mediates sensitization and its cellular manifestations in Aplysia. Notably, 5-HT bath application alone induces sensitization and increased TSN excitability. 14DFD prevents both sensitization and increased TSN excitability following aversive training. This project investigates whether 5-HT can induce sensitization and increased TSN excitability under 14DFD. In vivo bath application of 500 µM 5-HT for 1.5 h induced sensitization in 14DFD animals. However, the amount of sensitization was significantly smaller in 14DFD Aplysia compared to the 2DFD Aplysia, indicating 5-HT alone was not sufficient to fully induce sensitization under 14DFD. In vitro bath application of 50 µM 5-HT for 5 min induced increased TSN excitability in 14DFD preparations comparable to 2DFD preparations. These data suggest that 5-HT may be able to rescue the food deprivation-induced memory impairments in Aplysia.
Long-term influence of river alkalinity inflow on estuarine alkalinity in the northwestern Gulf of Mexico
Larissa Dias, Xinping Hu
Rivers and estuaries are important links between terrestrial and marine ecosystems in environmental flow and material exchange. Quantitative understanding about the influence of rivers on estuarine acidification and alkalinity is still lacking. Estuaries in the northwestern Gulf of Mexico exhibit a long-term decrease in alkalinity and pH. This phenomenon is more extreme at lower latitudes, where there are lower levels of precipitation and freshwater inflow. This study examines the long-term (multidecadal) influence of river alkalinity load and concentration on estuarine alkalinity loss and acidification in the northwestern Gulf of Mexico. Data on freshwater inflow and alkalinity concentration were analyzed using USGS FORTRAN Load Estimator Program (LOADEST). Nonparametric Kendall correlation and Sen-Thiel slope were used to determine the relationship between river or estuarine alkalinity and time (year) for eight major estuary systems. It is thought that riverine alkalinity input will have a positive correlation with estuarine alkalinity. Results of this study will allow stakeholders to better manage freshwater resources in both Texas and other similar climate zones across the world.
Livelihoods in transition across the Gulf of Mexico: Part 1 the Yucatan
Coral Lozada, David Yoskowitz
Understanding what policies and institutions exist across the three nations surrounding the Gulf of Mexico (GoM) - U.S., Mexico, and Cuba - allow for community leaders, resource managers, and policymakers to develop successful programs within their institutions. This Yucatan case study, the first of three, investigates external drivers of livelihood transitions using a convergent mixed-methods approach. The hypothesis: Communities that have policies allowing for co-management will have an increased capacity to positively adapt to transitioning livelihoods. Semi-structured field interviews with fishers were collected during the summer of 2019 and spring of 2020 concurrently with analysis of a targeted number of fishing policy and agency reports. Transcriptions were analyzed using MAXQDA software. Additionally, a timeline of the most important fishing policy and events that affected Yucatan fishers was created. Mexico’s fishing policy has taken a trajectory of most efficient use of resources in the past and has just recently (past 20 years) considered sustainably managing fisheries. Interviews revealed their own set of themes that were then synthesized with themes from the content analysis to determine if there was convergence. Preliminary results show some overlap occurred with “engagement between government and local communities” and “presence of feedback mechanism” being the most common themes in both datasets. These two themes could be the starting point from which communities, resource managers, universities, or NGO’s create meaningful interrelationships that make use of a community’s knowledge and synthesize it with that of an organization.
Long-term changes in contamination and macrobenthic communities adjacent to McMurdo Station, Antarctica
Terry Palmer, Andrew G. Klein, Stephen T. Sweet, Paul A. Montagna, Larry J. Hyde, Jose Sericano, Terry L. Wade, Mahlon C. Kennicutt II, Jennifer Beseres Pollack
Improved waste management at McMurdo Station, Antarctica beginning in the 1980s has been followed by decreases in polycyclic aromatic hydrocarbon (PAH) and metal contamination in the adjacent marine sediments. However, determining the effect of the decreased contamination on marine ecological indicators (macrobenthic fauna) is confounded by concurrent changes in climate cycles and other physical forces. Between 2000 and 2013, there was a decrease in concentrations of some contaminants including mercury, copper, organochlorines, and PAHs in marine sediments adjacent to McMurdo Station. PAH concentrations in Winter Quarters Bay decreased an order of magnitude from 2000/2003 to 2012/2013 and were within an order of magnitude of reference area concentrations by 2013. Macrobenthic communities did not indicate any sign of recovery and have not become more similar to reference communities over this same period of time. Temporal changes in macrobenthic community composition during the study period had higher correlations with climatic and sea ice dynamics than with changes in contaminant concentrations. The Interdecadal Pacific Oscillation climatic index had the highest correlation with macrobenthic community composition. The Antarctic Oscillation climatic index, maximum ice extent and other natural environmental factors also appear to influence macrobenthic community composition.
Despite large improvements in environmental management at McMurdo Station, continuing environmental vigilance is necessary before any noticeable improvement in ecological systems is likely to occur. The effects of climate must be considered when determining temporal changes in anthropogenic effects in Antarctica. Maintaining long-term monitoring of both contaminants and ecological indicators is important for determining the localized and global influences of humans on Antarctica, which will have implications for the whole planet.
A preliminary evaluation of the effects of oyster cage aquaculture on seagrass colony health
Ryan Rubino, Joe Fox
Seagrass acts as an essential habitat for many different marine species. Seagrass tends to grow in shallow areas with high light penetration and low wave action. These are also common sites for oyster aquaculture. With this overlap of land usage, and the emerging industry of Texas oyster aquaculture, it is important to understand the effects that oyster aquaculture may have on seagrass health. The goal of this study was to determine the impact that a small-scale oyster aquaculture operation had on nearby seagrass health in Copano Bay, TX. This study used standard seagrass monitoring procedures, in addition to water quality and sediment monitoring to determine if there was any impact caused by the presence of oyster aquaculture. Four seagrass beds (Halodule wrightii) at varying distances from the oyster cages (Upstream, 0m, 30m & 60m) were monitored for seagrass density, canopy height, max leaf length, turbidity, temperature, light intensity, salinity, DO, conductivity, nutrient concentrations, and sediment loading. Overall, there was very little differences between the four sites. The 60m site had significantly longer seagrass as well as higher sediment deposition rates. Both the 30m and 60m sites had significantly denser seagrass coverage. No other significant differences were found between sites. It was observed that the seagrass density decreases up the coast with the least dense site being upstream of the oyster cages. These results suggest that the differences in seagrass health between sites was not caused by the presence of oyster aquaculture, but instead by natural differences between the site locations.
Dynamics of diurnal CH4 emission from seagrass meadow and mangrove at Southern Texas
Hao Yu, Richard Coffin
Methane (CH4) is a greenhouse gas with an atmospheric warming potential 84-86 times over CO2 through 20 years (IPCC, 2014). Seagrass and mangrove are crucial sources of atmospheric CH4 from coastal areas. To discover the dynamics of CH4 cycling at subtropical seagrass and mangrove, we studied diurnal CH4 emissions at the sea-air and sediment-water interfaces and related environmental parameters in August 2019 at lagoonal estuaries of southern Texas, USA. Although seagrass beds and mangroves were at closely connected subtropical estuaries, they displayed distinct mechanisms in CH4 emission.
Dissolved CH4 concentration from seagrasses was higher overnight, expressing a tight relationship between photosynthesis and respiration. Plant mediation played a crucial role in CH4 production, oxidation, and transport. In comparison, the diel variation of dissolved CH4 concentration at a mangrove creek was controlled by tidal progression. Maximum CH4 level occurred during ebb due to the export of CH4 from inside of mangrove to the outside bay. Tidal pumping and tidal inundation were essential conduits for dissolved CH4 exchange between water and porewater. In both areas, sea-air CH4 fluxes were significantly affected by wind speeds, which hid related diurnal variations caused by physiological or tidal cycles. Our study also revealed a more significant contribution from seagrass to the local CH4 budget than from mangrove, indicating CH4 released from subtropical seagrass needs further investigation.