BUMP REU students
Erin McLean, Summer 2012
Mentor: Dr. Frank Hernandez, Dauphin Island Sea Lab
Erin conducted research along the coast of Alabama focusing on fish reproduction and how it’s connected to the Sargassum type of seaweed, performing experiments in mesocosm environments. Erin will be presenting her summer REU research at the ASLO (American Society of Limnology and Oceanography)’s Ocean Sciences meeting in February
Abstract: Pelagic Sargassum mats provide valuable habit for fishes and invertebrates in an otherwise featureless open ocean environment. An understanding of trophic dynamics within Sargassum faunal assemblages is critical in assessing its value as “nursery” habitat for associated juvenile fishes. We used mesocosm experiments to compare the foraging behavior and success of four fish species commonly associated with Sargassum as juveniles: Seriola rivoliana, S. dumerili, Stephanolepis hispidus and Aluterus scriptus. Replicate trials (48 h) with and without Sargassum habitat were conducted using a single juvenile fish predator and either Sargassum shrimp or small S. hispidus (<1.5 cm) as prey (n=20). Shrimp mortality was significantly higher in trials without Sargassum for all predator treatments. Overall, the Seriola spp. were more efficient predators in the absence of habitat than the filefishes, but when Sargassum was present, prey consumption was equal for the two groups. Also, the Seriola spp. consumed more fish prey than shrimp prey when Sargassum was present. These results suggest that species-specific foraging behaviors need to be considered when assessing nursery habitat value and function for Sargassum.
Jessie Mathews, Summer 2012
Can coral geochemistry be used to reconstruct salinity and temperature variability in the Indonesian Throughflow Current over the last 200 years?
Background: As the only low latitude interocean conduit, the Indonesian Throughflow (ITF) annually transports surface and thermocline depth water from the western Pacific Ocean north of the equator to 12°S in the eastern Indian Ocean and may be influential to global thermohaline circulation. Today, the net result of the ITF is a cooling and freshening of the Indian Ocean thermocline. In this project we will be using cores from the coral Porites sp. previously collected from Kapoposang in the southern Makassar Strait near S.W. Sulawesi and from Gili Meno in the Lombok Strait near Bali to develop near-monthly resolution coral oxygen isotope (d18O) and Sr/Ca Records in the late 20th century. The goal is to develop a calibration dataset for interpreting the paleo‐record preserved in the same cores over the last 200 years.
This project was laboratory based at Lamont-Doherty Earth Observatory, Columbia University.
Julia Luthringer, Summer 2011
The 2011 Atchafalaya River Flood and Benthic Metabolism and Nutrient cycling responses in the Atchafalaya River Delta Estuary
Mentor: Dr. Brian Roberts, Louisiana Universities Marine Consortium
In May 2011, the Morganza Spillway was opened for the first time since 1973 in attempt to relieve southern Louisiana cities from extensive flooding by the Mississippi River. In doing so, over 115,000 ft3/s of water, sediment, and particulate and dissolved organic matter were flushed into the Atchafalaya River, flooding the swamps and wetlands in the Atchafalaya River Basin. In this study, we aimed to document the changes in benthic metabolism and nutrient uptake rates in the Atchafalaya River Delta Estuary (ARDE) by incubating sediment cores taken along a transect offshore of the Wax Lake Delta. Cores were collected and incubated three times post-flood: 2 (13 June 2011), 6 (12 July 2011), and 9 (2 August 2011) weeks after peak flow. Results indicate that there was no strong temporal trend between respiration rates between any of the sites, and that metabolic rates are similar to or lower than rates measured in 2009 and 2010. Spatially, the farthest off shore site (WLO6) demonstrated lower respiration values, especially during the July and August experiments. Lower benthic respiration rates were observed at certain temperatures than could have been predicted from past data, indicating that some other factor besides temperature (such as increased sedimentation) may be reducing rates of metabolism in the estuary sediments. The point at which the ARDE sediments switch from a DIN sink to a DIN source was also documented through core incubation experimentation, and found to be approximately 15-20 km offshore from the delta, as the farthest offshore site was hypoxic, and ammonium fluxes tend to occur under hypoxic conditions. Data collected (but not analyzed) from the August experiment may indicate that the site 15 km off shore had turned to a DIN sink after the flood. Since hypoxia was shown to have moved inshore (to WLO5) in the last (August) experiment, it is likely that WLO5 has become a DIN source, but the nutrient data from this experiment have yet to be analyzed.
Reena Clements, Summer 2011
Mentor: Dr. Tom Schultz, Duke University Marine Lab
My research project focused on biological rhythms, specifically circadian (day/night) or circatidal (high/low tide) in fiddler crabs, Uca pugilator. I studied both the behavioral and genetic components of these rhythms. To study the specific environmental cues responsible for rhythms, U. pugilator were kept under constant conditions and activity was monitored for periods greater than one week. U. pugilator were found to mainly follow a circatidal rhythmic pattern with some circadian influence. I also examined the Hypoxia Inducible Factor 1-alpha (HIF-1a) gene as a possible candidate gene that contributes to regulation of the internal clock regulator. This gene was chosen as it has protein domains (Per-Arnt-Sim, PAS, and basic helix-loop-helix, bHLH) similar to those found in known clock regulator genes of higher organisms. The gene was found to show some oscillatory behavior over a 24 hour period that was consistent with timing of rhythms established in the behavioral experiments, but further studies must be conducted to support this claim.
Christina Teng, Summer 2011
I participated in an NSF-funded REU last summer (2011) at the University of Texas at Austin Marine Science Institute in Port Aransas, Texas. I worked with two faculty mentors on a biogeochemistry project. I investigated the concentration and composition of amino acids in the Eastern oyster, Crassostrea virginica, collected from the south Texas coastal bend area to see if they could be used to reconstruct a picture of historic climate patterns. The program lasted from May 31 to August 9, 2011. I presented an oral presentation in a symposium at the end of the internship, and later presented a poster at the ASLO Ocean Sciences Meeting in Salt Lake City (February 20-24, 2012).