Field Experiences in South Texas
The University of Texas Marine Science Institute

REUfest is a summer research program for undergraduates at the University of Texas Marine Science Institute. Student projects take advantage of the wide variety of coastal habitats near the Institute, including shallow bays, hypersaline lagoons, seagrass beds, estuaries, mangroves, and marshes.

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DEGRADATION OF DISSOLVED ORGANIC MATTER BY MICROBIAL AND PHOTOCHEMICAL PROCESSES IN TEXAS RIVERS

August 5th, 2013 Posted in Uncategorized | No Comments »

Hi! I’m Jess Smith and I worked in Dr. Jim McClelland’s lab this summer. Here’s a snippet of my abstract:

Dissolved organic matter (DOM) is a little explored field in Texas rivers, which can be described in part by dissolved organic carbon (DOC) and colored DOM (CDOM). The degradation of river water by light and microbial sources can indicate the fate of the matter in the estuary. Three rivers were sampled for this experiment: the Nueces, the San Antonio, and the Guadalupe. There were three methods of analysis were utilized in this experiment: directly measuring the DOC content for an estimate of quantity of DOM, utilizing the CDOM absorbance scan between 275 and 295nm for spectral slope which is an indication of molecular weight, and finally using the DOC content and absorbance at 254 nm for SUVA (a measure of aromaticity). The larger the molecular weight, the more difficult it is for microbial sources to break down the matter. Similarly, the more aromatic the matter, the more difficult it is to break down. The Nueces watershed contains a lake creating autochthonous DOC, easier to break down and less aromatic, while the Guadalupe watershed contains more allochthonous DOC which is recalcitrant and aromatic. The San Antonio follows the Nueces’ pattern in the DOC and S275-295 results, while acting more like the Guadalupe in the SUVA results, having anthropogenic DOC sources that act differently feeding into its watershed. These three rivers along the Texas coast show that, under normal conditions, DOM lability and quality varies greatly, owing to the diverse characteristics of the watersheds.

This has been a great summer, and much different than staying in Pennsylvania or Connecticut. There’s always a lovely breeze and the beach is so close. I’ve grown close to everyone here, and will miss hanging out in the perpetually sunny Southern Texas!

Interview: Aubrey Lashaway

August 5th, 2013 Posted in Uncategorized | No Comments »

Aubrey Lashaway got her bachelor’s degree in Environmental Science at University of Michigan. While attending University of Michigan Aubrey studied aquatic ecology. Her main interest was elasmobranch biology/ecology but soon became introduced to plankton ecology. While she did not initially feel excited about plankton she soon grew interested in their role in the food chain. Her research in Michigan focused primarily on diatom rejuvenation of diatoms in Lake Eerie. She continued on to get her first master’s degree at Penn State University, in Wildlife and Fisheries Science.
Many factors influenced her decision to come to UT for her PhD, as her path was connected beginning from her undergraduate studies. Her advisor at Michigan had known her future advisor at Penn State. She worked as a lab tech there and after earning a master’s degree worked with the national park service. Her boss at the national park service knew Dr. Jim McClelland, who referred her to her current advisor Dr. Deana Erdner. She also liked that Michigan and UT were so similar, and that a UT degree is a well respected degree.
When Aubrey began her stint at UT she participated in a mandatory TA fellowship. During this time she realized that she enjoyed education leadership a great deal. This began her transition from obtaining a PhD in research to earning an additional masters degree instead. She regretted not having been introduced to teaching earlier in her academic career and no longer wanted to continue solely in research. She feels that teaching offers an avenue that makes science available to the public in a way that research cannot. She is more interested in working with a citizen science program, creating inquiry-based learning with the population. She would like to help get students more interested in science and math. In the future she may pursue a teaching doctorate.

Investigating the effectiveness of geochemical proxies of hypoxia exposure in otoliths of Atlantic croaker and closing thoughts on the REU

August 5th, 2013 Posted in Uncategorized | No Comments »

Hello everyone, my name is Branden Kohler. This summer I have been investigating the effectiveness of geochemical proxies of hypoxia exposure in otoliths of Atlantic croaker with my mentors: Dr. Ben Walther and John Mohan. Hypoxia, or low dissolved oxygen content can have a significant negative impact on growth and reproductive health of fishes. Determining an accurate proxy for hypoxia exposure that reflects lifelong individual exposure histories would allow for more accurate assessments about the impact of hypoxic events. Fish otoliths, or ear stones, grow in ring-like patterns throughout the fish’s life and certain ions present in the water column have been shown to be incorporated into the rings of the otolith. Redox-sensitive elements such as manganese (Mn) incorporated into otoliths could therefore be valuable proxies for hypoxia exposure.  The purpose of this research is to determine if Mn found in the otoliths of Atlantic croaker (Micropogonias undulatus) indicates hypoxia exposure in the northern Gulf of Mexico.  Fish (N=120) were collected from sites during research cruises in October 2011 (flood year) and August 2012 (drought year), to determine if there would be a difference in otolith Mn between a large hypoxic zone caused by flooding and a small hypoxic zone caused by drought. The otoliths were sectioned to expose the core and analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in order to determine the concentrations of elements along a life history profile for each fish. Unexpectedly, there was no significant difference in average, maximum or total Mn:Ca in otoliths according to year of collection. There was significant variation by region, with sites in the eastern Gulf of Mexico, which were putatively normoxic control sites, showing significantly higher ratios of Mn:Ca than the central or western regions where hypoxic zones typically occur. This geographical pattern could reflect differences in the sediment composition between the eastern and central/western regions. The effectiveness of manganese as an accurate proxy of hypoxia exposure in fish does show promise in certain regions, but more research is needed to validate it’s possible utility in other locations.

 

My time spent here in Port Aransas has been truly amazing. There definitely have been many great times and fun exploits with great people. While I’m leaving on Friday to return to Pennsylvania in order to finish off the summer and my education back at Kutztown, I will treasure all of the memories and great friends I have made here and would be thrilled to come back again.

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Effects of Crude Oil on Coastal Diatom Health

August 5th, 2013 Posted in Uncategorized | No Comments »

Hello my name is Emily Pinckney and this summer I studied the effects of crude oil on coastal diatom health with the help of my mentor, Dr. Deana Erdner. The effects of oil on marine ecosystems have become a subject of intense study since the Deepwater Horizon oil spill in 2010. One area that has historically not received much attention is the effect of oil on phytoplankton. Because phytoplankton are major primary producers, forming the base of aquatic food webs, negative impacts from oil exposure can have knock-on effects throughout the ecosystem. Similar studies in the past have been performed to observe the interaction between oil and phytoplankton, and whether oil leads to cell death. My experiment is different because I examined both sublethal stress and death in phytoplankton exposed to both oil and dispersant at realistic concentrations.
I tested two species of coastal diatoms, Pseudosolenia and Thalassiosira. After exposure to different concentrations of oil plus dispersant, I measured total cell numbers, the proportion of dead cells, and the proportion of cells that showed signs of oxidative stress. The cultures were tracked for 4 days. The two species showed different responses to the oil and dispersant mixture. Thalassiosira did not show oxidative stress and the mixture of crude oil and dispersant neither hurt nor helped the cells. However, Pseudosolenia showed an increase in oxidative stress, a short spike in cell death, and a stimulation of growth at the higher oil concentrations. These results increase our knowledge of the impact of oil use and the importance of phytoplankton to our world. Future studies might focus on verifying these results, and looking more into the role of dispersant in cell health.

I’ve really enjoyed my time here in Port Aransas and all the adventures I experienced this summer. Even though I have to leave Texas behind, I’m taking with me amazing memories and some life-long friendships.

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