Applications are now available for the summer 2014 REU at the UT Marine Science Institute. Applications are due March 7, 2014 and program dates are June 2 – August 8, 2014. Click on the Applications tab in the header bar to access the electronic application and materials. Any questions? Just email us at UTMSI.REU@gmail.com
The past two months have gone by so quickly! I have been working with Dr. Rodrigo Almeda this summer and I am happy to say that my project has turned out well. I’m hoping to attend a couple conferences to present the research that I have conducted this summer. I’m extremely thankful for the support I’ve received from my mentors as well as from my fellow REU-ies. My abstract below explains my project in more detail.
Petroleum is one of the most common pollutants released into marine environments. The use of dispersants is a common response to oil spills, as occurred during the Deepwater Horizon oil spill in the Gulf of Mexico in 2010. However, little is known about the toxicity of chemical dispersants and dispersant-treated crude oil to zooplankton. In addition, increasing evidence suggests that UV radiation (UVR) may play an important role on the toxicity of crude oil. The objectives of this study were to determine; (i) if the dispersant Corexit 9500A increases the acute toxic effects of crude oil to copepods (ii) the effects of UVR on the toxicity of crude oil to copepods. We investigated the lethal and sublethal effects of crude oil alone, dispersant-treated crude oil and chemical dispersant and, the influence of UVR exposure, in adults and nauplii of the copepod Acartia tonsa and Pseudodiptomus pelagicus. At the ratio of dispersant to oil commonly used in oil spills (1:20), the combination of oil and dispersant increased mortality and reduced egg production, hatching success, and egestion rates in adult stages of A. tonsa, compared to crude oil alone. Copepod nauplii survival and growth rates were significantly lower when exposed to dispersant-treated crude oil than to crude oil alone. Median lethal concentration (i.e., concentration required to kill half the members of a tested population, 48 h) for copepod nauplii decreased from 1.9 µL L-1 without UVR to 1.2 µL L-1 with UVR. Similarly, we found that toxicity of crude oil and crude oil plus dispersant increased from 24% to 66% and from 67% to 100%, respectively, under UVR exposure. Overall, our results showed that copepod nauplii are highly sensitive to crude oil, and that toxicity of crude oil to zooplankton increases with the use of dispersant and under UVR exposure.
I’m Caroline Watson and I’ve been working with Dr. Andrew Esbaugh this summer. We investigated the physiological response of S. ocellatus to freshwater challenge over discrete time periods (0, 8, 24, 72 and 168 h post-exposure). We observed individuals in 24, 72 and 168 h freshwater exposures showed a significant decrease in plasma osmolarity. Plasma Na+ concentrations were maintained at constant levels in all exposures, while individuals in the 24 and 72 h exposures exhibited plasma Cl- decreases. Plasma Ca2+ and Mg2+ concentrations also displayed persistent decreases throughout exposure. A similar pattern was observed for the muscle ions, however no change in muscle water content was observed. Little intestinal fluid was collected in the 8 hour treatment and was absent in later time points, indicating early cessation of drinking. S. ocellatus appear capable of immediately regulating Na+ ions in their systems post freshwater exposure. While Cl-, Ca2+ and Mg2+ ions show a decrease between 8 and 24 h, the data implies that over an extended period the animals are able to regulate ions at near normal levels, thus maintaining osmotic balance. The immunohistochemical analysis of gills showed that cellular mechanisms for Na+ excretion in saltwater are not present in 168 h freshwater exposed individuals, namely the basolateral Na+, K+, 2Cl- co-transporter. This suggests that S. ocellatus exhibit phenotypic flexibility with respect to their osmoregulatory pathways. Further gene expression analysis may demonstrate patterns of upregulation reflective of ion uptake mechanisms.
I have learned so much this summer! I am extremely grateful for the support I received from my mentor, many other faculty members and students, as well as from my peers. The experience I have gained in Port Aransas is irreplaceable, as are the memories!
I can’t believe it’s almost the end! I’ve had an amazing experience in Port A this summer gaining research skills and meeting so many fellow students dedicated to understanding and protecting the marine environment. I am excited to report that my experiments with larval fish have gone well, and that the data are starting to tell and interesting story. The following is a little bit more detail about my work.
Less than 0.1% of marine fish larvae survive to recruitment, but it is unclear which factors contribute to the success of certain individuals over others. For many species, early larval stages inhabit pelagic waters and then move to a specific benthic habitat. This transition is known as settlement, however little is known about this process for species that live in non-coral reef environments. In this study, the role and strength of the olfactory response to settlement habitat cues was evaluated for red drum, Sciaenops ocellatus, an inhabitant of the estuarine waters of the Gulf of Mexico. Red drum larvae settle into seagrass beds after passing through tidal inlets during the late summer and early fall. The seagrass beds may emit a complex olfactory signal the larvae can use to locate settlement sites. In this experiment, I used a “Y” maze to test larval preference for different concentrations of lignin, a structural compound found in seagrass tissue that affected larval swimming speed in a previous study. Experimental treatments included (1) lignin + artificial sea water, (2) 0.1 concentration lignin + artificial sea water, (3) water collected from a seagrass bed, (4) lignin + sterilized seawater, (5) water collected from the shipping channel, and (6) Artemia + artificial sea water. Treatments were compared to artificial sea water as a negative control and Artemia + artificial sea water as a positive control. Settlement-sized larvae spent more time (16.2%) in water from the seagrass beds compared to control seawater. Presettlement-sized larvae did not show a preference for any of the treatments. Further research into the signals that attract larvae to seagrass settlement areas has the potential to improve management of threatened fish species and that of declining seagrass populations.
I want to thank my mentors Lisa Havel and Dr. Lee Fuiman for giving me excellent guidance during this research. I will miss them and all of the FAML staff when I leave! Wish me luck at the symposium.