Why Cleaning our Oceans Could Also Reduce Obesity

Samera Mulatu, Georgia Southern University

The problem: Charleston Harbor is undergoing massive dredging to make way for super tankers. There are concerns that banned legacy compounds buried in the sediments, such as tributyltin (TBT), will be brought up into the harbor waters as a result of the dredging. A related concern is that oil spills will become more common and involve the release of cleanup compounds into the water column, including Span 80 and dioctyl sodium sulfosuccinate (DOSS). These three compounds and others are known to act as endocrine disrupting compounds (EDCs), which disrupt the Retinoid X Receptor (RXR) pathway. In mollusks, RXR disruption induces imposex development (when female mollusks develop male sex traits). One goal of my project is to measure the rates of imposex in the Eastern mud snail (Tritia obsoleta) within different sites in Charleston Harbor and to see if these rates increase over time with dredging.

The same chemicals that cause imposex are used in medications, processed foods (e.g. homogenized milk), textiles, paints, and cosmetics.  Because the identification and study of many EDCs is fairly new and upcoming, their effects on the human body are still not fully understood. Those EDCs found to promote weight gain are called “obesogens.” Early exposure to obesogens can detrimentally affect a child’s health into adulthood! These obesogens can persistently alter hormonal signaling pathways in children, which can lead to permanent metabolic damage.

Obesity in the United States is at an all-time high. Approximately half of the population is predicted to be obese by 2020.  This is a serious health problem because obesity can drastically increase the likelihood of developing cancer, diabetes, and heart disease. Many people associate obesity with lack of exercise. However, it should be noted that obesogens can reduce energy, increase appetite and change behaviors associated with weight gain.


The author (right) collecting mud snails (Tritia obsoleta).  Photo: Dr. Spyropoulos.

I would like to give a big thank to Dr. Demetri Spyropoulos for guiding me in my research. Also to the Fort Johnson REU Program, NSF DBI- 1757899, for providing me with the funds to complete this project.

Related research

Hotchkiss, A.K, A.G.Leblanc, R.M. Sternberg. 2002. Synchronized expression of Retinoid X Receptor mRNA with Reproductive Tract Recrudescence in an Imposex- Susceptible Mollusc. Environ. Sci Technol. 42: 1345- 1351.

Ravitchandirane, V. S, M.Thangaraj. 2013. Phylogenetic Status of Babylonia Zeylanica (Family Babyloniidae) Based on 18S rRNA GENE FRAGMENT.Annals of West University of Timisoara, ser. Biology. 1(2): 135- 140.

Barron- Vivanco, B.S, D. Dominguez- Ojeda, I.M. Medina- Diaz, A.E. Rojas- Garcia, M.L. Robledo- Marenco. 2014. Exposure to tributyltin chloride induces penis and vas deferns development and increases RXR expression in females of the purple snail (Plicopurpura pansa). Invertebrate Survival Journal. 11: 204-2012.

Horiguchi, T., M. Morita, T. Nishikawa, Y. Ohta, H. Shiraishi. 2007. Retinoid X Receptor gene expression and protein content in tissues of the rock shell Thais clavigera. Aquatic Toxicology. 84: 379-388.


Oil Spills, Climate Change, and Grass Shrimp

Cheldina Jean, American University


The problem: The Deepwater Horizon oil spill that occurred in April 2010 is known as the nation’s most detrimental offshore environmental disaster. Over the course of almost three months, approximately 134 million gallons of crude oil was released into the Gulf of Mexico. Tens of thousands of marine organisms, including dolphins, sea turtles, 93 bird species, and marine plants such as mangroves, whose roots hold together the eroding coasts of Louisiana and South Florida, were negatively affected by this calamity.

Estuarine organisms, particularly sensitive early life stages, are particularly vulnerable to oil pollution given the stressful environmental conditions of their habitat. Estuaries experience daily tidal fluctuations in light penetration, temperature, and salinity; and the range of these factors is expected to increase with global climate change. My project this summer consists of testing the effects of oil on the early life stages of estuarine organisms under various environmental conditions. This research will help us understand how their populations may be affected.

Grass shrimp are commonly found in estuarine waters of South Carolina and along the Gulf and Atlantic coastlines. Grass shrimp are detritivores, playing an important role in the salt marsh by recycling the nutrients of decaying matter back into the food chain. They are also an important prey species for commercially and recreationally important marine organisms, such as spotted sea trout and red drum (Coen & Wenner, 2005). This research project focuses on the role abiotic stressors such as ultraviolet light, temperature, and salinity play on the survival of grass shrimp (Palaemonetes pugio female grass shrimp embryos and larvae exposed to oil.


Gravid (egg carrying) female grass shrimp (Source)

Crude oil is a complex mixture of chemicals, including a group of compounds called polycyclic aromatic hydrocarbons (PAHs). Some PAHs are chemically altered in the presence of ultraviolet (UV) light, causing an increase in the toxicity of oil (Alloy et al., 2017). In addition, thermal stress from rising global temperatures may affect the ability of marine organisms to metabolize and detoxify contaminants they take up (DeLorenzo et al., 2009). Salinity is another environmental factor to consider because it can alter the solubility of chemical contaminants and thus change the level of chemical exposure.

Every oil spill has different conditions surrounding it, so it is important to understand how factors such as UV light, temperature, and salinity affect oil toxicity in the early life stages of estuarine organisms. Although we cannot eliminate oil pollution in the ocean, the results of this research will help us understand how multi-stressors and oil affect the early life stages of aquatic organisms and will help governments and citizens take action in oil spill response and remediation.

I would like to thank my mentor Marie DeLorenzo and co-mentor Katy Chung for guiding me through this research. This project is supported by the Fort Johnson REU Program, NSF DBI-1757899.

Literature Cited:

  1. Alloy, M., Garner, T. R., Bridges, K., Mansfield, C., Carney, M., Forth, H., … & Bonnot, S. (2017). Co‐exposure to sunlight enhances the toxicity of naturally weathered Deepwater Horizon oil to early lifestage red drum (Sciaenops ocellatus) and speckled seatrout (Cynoscion nebulosus). Environmental toxicology and chemistry, 36(3), 780-785.
  2. Coen, L., & Wenner, E. (2005). Grass shrimp. South Carolina State Documents Depository.
  3. DeLorenzo ME, Wallace SC, Danese LE, Baird TD (2009) Temperature and salinity effects on the toxicity of common pesticides to the grass shrimp, Palaemonetes pugio. J Environ Sci Health B 44:455–460.



Kaylie Anne Costa, University of Miami

The problem: Do you hate the cold? Well manatees can’t stand it either! Every year Florida manatees (e.g., West Indian Manatee, Trichechus manatus latirostris) migrate to warmer waters during the winter months. In the past, they have used locations such as springs, layers of warm water created by salinity anomalies, and even the effluents from coastal power plants to stay warm. Unfortunately, new developments and recreational activities are taking over the natural warm water sources and most of the power plants are shutting down, so manatees have no haven for warm water.


Manatees utilize the warm effluent water of a coastal power plant in Riviera Beach, Florida (Source)

When water temperatures fall below 20 °C (68°F), Florida manatees become susceptible to cold stress syndrome (CSS), which is a breakdown of normal biological and immunological processes that often leads to death (Bossart 2001). Manatees experiencing CSS have characteristic lesions and other symptoms like emaciation, lethargy, fat atrophyand loss, epidermal hyperplasia, pneumonia, and myocardial degeneration (Bossart, 2001; Bossart et al., 2003). CSS plays a major role in major manatee die off events and the number of cases continues to increase as manatees lose more and more warm water refuges to development and recreation. I will be expanding the current scientific knowledge of CSS by analyzing the lipids (aka fats) and metabolites, which are the products remaining after biological processes such as digestion, respiration, maintaining homeostasis, etc. in manatee plasma samples using mass spectrometry in hopes of learning more about metabolism for therapeutic applications.

Protecting Florida manatees is important for so many reasons. First off, the US Endangered Species act listed the Florida manatee as endangered in 2001, but recently reduced their status to only threatened in 2017 (Public Affairs Office, 2018). Without intervention, this species could easily return to its endangered status. Secondly, marine mammals are great sentinels to model how environmental changes will impact human health due to their physiological similarities, long life spans, and thick blubber’s ability to store large amounts of contaminants (Bossart, 2011). Thirdly, manatees help control the growth of sea grass beds. The presence of healthy sea grass beds allows the ecosystems around them to thrive. Lastly, manatees support economies through ecotourism. This research is necessary to protect Florida manatees from this understudied condition.

A huge thank you to my mentor Dr. John Bowden and co-mentor Dr. Mike Napolitano as well as everyone at NIST for all of their help and guidance. I would also like to thank the National Science Foundation for funding and the Fort Johnson REU program for making this research possible (NSF DBI-1757899).


Public Affairs Office. (2018, February 7). Florida Manatee -Issues and Information. Retrieved June 17, 2018, from https://www.fws.gov/northflorida/manatee/manatees.htm

Bossart, G. (2001) Manatees. In: L. Dierauf & F. Gulland (eds.) Marine Mammal Medicine, pp. 939–960. CRC Press, Boca Raton, FL.

Bossart, G. D., Meisner, R. A., Rommel, S. A., Ghim, S. J., & Jenson, A. B. (2003). Pathological features of the Florida manatee cold stress syndrome. Aquatic Mammals, 29(1), 9–17.

Bossart, G. D. (2011). Marine mammals as sentinel species for oceans and human health. Veterinary Pathology, 48(3), 676–690.

Small Steps to Save the Sea Turtles

Kelly Townsend, Elmhurst College


Turtle trawl on the R/V Lady Lisa. Photograph authorized by NMFS Section 10(A)(1)(a) permit 19621.

The problem: Do you like sea turtles? As for me, I have fallen in love with these cute creatures who occupy parts of the ocean. Seeing them pop their heads up or glide through the water always amazes me, but many species are endangered. A lot of effort has gone into saving them since sea turtles play an important role in the marine ecosystem. The marine ecosystem makes up a part of our world that is deeply loved but also threatened. Sea turtles help marine ecosystems function by limiting the amount of seagrass beds and sponges through consumption (McClenachan et al., 2006). Therefore, sea turtles presence in the environmental community is key to ecosystem restoration where their numbers have dropped and seagrass disease has been able to spread and coral overgrowth has increased. In addition, sea turtles also play an important role in ecotourism. Places like Costa Rica, United States, and Australia use sea turtles as a source of income by promoting tourism in areas where they live or nest, offering turtle walks, and selling souvenirs (Campbell, 2003). Since sea turtles act as an important resource for humans, there has been much effort into rehabilitating injured sea turtles and researching them in order to determine better prognostic indicators and courses of treatment. Sea turtles are important to us environmentally and economically, so saving them from going extinct requires the most reliable research and data possible to make that happen



Turtle nesting beach located in Tortuguero, Costa Rica.

RNA and plasma proteins are both potential indicators for overall organismal health, but they can degrade quickly if not properly stored. Plasma protein concentrations in sea turtles can help wildlife veterinarians diagnose a disease and create a proper treatment plan (Gicking et al., 2004). Therefore, measuring plasma proteins in archived samples can indicate when or if a . particular disease developed in sea turtles. In addition, RNA concentrations and quality are good indicators of general health. High ratios of RNA/DNA has shown indications of increased cellular protein synthesis along with increased growth potential which means the sea turtle is growing properly (Vieira et al., 2014). However, in order to use archived samples to accurately track health indicators such as plasma proteins and RNA, it is vital to know if storage conditions allowed degradation of these molecules.


Whole blood tubes used for RNA analysis.

This study aims to investigate RNA and plasma protein stability at different temperature treatments over periods of time. Samples will be maintained in favorable conditions along with unfavorable conditions to analyze the difference between the qualities. By knowing what happens on a molecular level to blood when storage conditions go wrong, we hope to eliminate the use of low quality samples used in research. Freezers malfunction, people forget to put samples away, and blood may not be put in the proper place so the results of this study will become a reference to those researchers who experience these tragedies.

I would like to thank Dr. Jennifer Lynch, Jennifer Trevillian, and Jennifer Ness with the National Institute of Standards and Technology for being my supportive and awesome mentors. This project was made possible by the samples collected by Dr. Michael Arendt and the funding from the National Science Foundation (NSF DBI-1757899) supported by the Fort Johnson REU program.


Campbell L. 2003. Contemporary culture, use, and conservation of sea turtles. In: Lutz PL, Musick JA, and Wyneken J (Eds). The biology of sea turtles, volume 2. Boca Raton, FL:   CRC Press.

Gicking JC, Foley AM, Harr KE, Raskin RE, Jacobson E. 2004. Plasma protein electrophoresis of the atlantic loggerhead sea turtle, Caretta caretta. Herpetological Medicine and Surgery 14:13-18.

McClenachan L, Jackson JBC, Newman MJH. 2006. Conservation implications of historic sea turtle nesting beach loss. Front Ecol Environ 4:290-296.

Vieira S, Martins S, Hawkes LA, Marco A, Teodosio MA. 2014. Biochemical indices and life traits of loggerhead turtles (Caretta caretta) from cape verde islands. PLoS ONE 9:e112181.

Not all superheroes wear capes!

Connor Graham, Francis Marion University


The problem: When you think of superheroes, does the man in the red cape and ‘S’ on his chest come to mind? That’s understandable, but could it be possible that our greatest protectors are embedded in the sediment along our saltmarshes? Well, it is and these potential protectors are known as Benthic diatoms.

Benthic diatoms, plant-like microorganisms, are bioindicators, which means they can be used to determine the health of an environment. In South Carolina, environmental health is crucial to the prospering tourist areas, booming commercial fishing, and overall human health of the year-round residents. Poor environmental health could lead to a decline in economic benefits, decrease in seafood-and-shellfish heavy diets, and the fitness of the human population living in those areas. Benthic microalgae (BMA) are considered to be great bioindicators because of they have a short lifespan, they are abundant, easy to sample, sessile, and respond to specific stimuli (Desrosiers et al. 2013). But the question is can we use diatoms as bioindicators for South Carolina’s various salt marshes? Are they the superheroes we did not even know we had?


Sampling site at Folly Beach. Photo: Max Cook.

My project this summer consists of sampling saltmarsh mud on at least five barrier islands along South Carolina’s coast to better understand the biogeography of BMA and assess their potential as bioindicators for saltmarshes. Barrier islands are land areas that are now inhabited by humans that protect inland territories from natural disasters.

I am comparing the community structure of the BMA’s on the various islands. If there is little to no variation in the benthic microbial communities gathered from the islands, bioindication can be used to determine their health. To use them as bioindicators will require the community structure to be similar on all the islands.


Measuring the amount of light at Folly Beach. Photo: Max Cook.

Whether or not the community structure is similar or different will then be compared to the geographical distance of the sample sites and islands. Looking at the biogeography (geographical distribution of living things) of the BMA community has not been a priority, because we assume “everything is everywhere” (Baas-Becking 1934, as cited in Janne Soininen 2012) when speaking of microorganisms. Hopefully, by determining the diatoms’ community diversity on the islands, South Carolina is one step closer to thriving.


Kristina, Max, and I in the clean room at Hollings Marine Lab analyzing grain sizes of sediment samples. Photo: Jennifer Ness.


I would like to thank my mentors: Dr. Craig Plante and Kristina Hill-Spanik (CofC). Also, I would like to thank my lab partner Max Cook (CofC). This project is supported by the Fort Johnson REU Program, NSF DBI-1757899.

Literature Cited:

Desrosiers, C., J. Leflaive., A. Eulin. and L. Ten-Hage. (2013) Bioindicators in marine waters: Benthic diatoms as a tool to assess water quality from eutrophic to oligotrophic coastal ecosystems. Ecological Indicators. 32: 25–34.

Soininen J. (2012) Macroecology of unicellular organisms – patterns and processes. Environmental Microbiology Reports, 4(1): 10-22.

Gracilaria: A Weedy Invader

Nick Partington, St. Olaf College

Screen Shot 2018-07-03 at 10.37.44 AM

The problem: Invasive species come in many different shapes and sizes, with a great variety of effects on the environment. For example, some invasive species infiltrate and destroy native trees, while some are introduced into lakes where they may displace native species and absorb nutrients. Whether aquatic or terrestrial (or perhaps even extraterrestrial), invasive species have been shown to have considerable effects on the environments they invade, and have been proven to play a major role in affecting global change (Vitousek, 1996). Gracilaria vermiculophylla is an invasive seaweed that has been introduced to many regions throughout the world, including the east coast of the United States (Thomsen, 2006, 2007, 2009). It takes the form of a thin, brownish red algae and originated off the coasts of Japan, from which it has dispersed throughout the world by hitching a ride in the ballasts of commercial ships (Krueger-Hadfield, 2017). In South Carolina, it can be observed in dark patches on beaches when the tide recedes.


A patch of Gracilaria vermiculophylla on Grice Beach, where we will be collecting samples this summer.

Many small fishes use G. vermiculophylla as habitat; it provides them with food, as well as shelter from predators (Byers, 2012). Many of these fishes serve as prey to larger fishes, and eventually the energy they contain travels up the food web to commercially and recreationally important fishes across the world, including within the Charleston harbor area. That is, G. vermiculophylla provides habitat to fishes, which in turn serve as food for larger fishes that are consumed by humans. Having a good understanding of how these fishes use G. vermiculophylla as habitat can aid the conservation and fishing industries in understanding this low-level component of the food web.

My research project this summer is aimed at improving this understanding. We will be replicating the design of a study implemented in the summer of 2017 by studying fish communities occurring in patches of Gracilaria vermiculophylla. Particularly, we will be exploring differences in the abundance and diversity of fishes utilizing dense patches of G. vermiculophylla as compared to sparse patches. We are also interested in any differences that might exist between dense and sparse patches concerning habitation patterns among different developmental stages of these fish species. Our findings may support that which was discovered last summer, or they might reveal a completely new piece of information. I am excited to see what we will find!

Special thanks to Dr. Tony Harold for his guidance in this research project. This project is funded by the National Science Foundation and is supported by the Fort Johnson REU Program, NSF DBI-1757899.


Byers, J. E., P. E. Gribben, C. Yeager, and E. E. Sotka. 2012. Impacts of an abundant introduced ecosystem engineer within mudflats of the southeastern US coast. Biological Invasions 14:2587-2600.

Krueger-Hadfield, S. A., N. M. Kollars, A. E. Strand, J. E. Byers, S. J. Shainker, R. Terada, T. W. Greig, M. Hammann, D. C. Murray, F. Weinberger, and E. E. Sotka. 2017. Genetic identification of source and likely vector of a widespread marine invader. Ecology and Evolution 7:4432-4447.

Thomsen, M. S., K. J. McGlathery, and A. C. Tyler. 2006. Macroalgal distribution patterns in a shallow, soft-bottom lagoon, with emphasis on the nonnative Gracilaria vermiculophylla and Coldium fragile. Estuaries and Coasts 29:465-473.

Thomsen, M. S., K. J. McGlathery, A. Schwarzschild, and B. R. Silliman. 2009. Distribution and ecological role of the non-native macroalga Gracilaria vermiculophylla in Virginia salt marshes. Biological Invasions 11:2303-2316.

Thomsen, M. S., T. Wernberg, P. Staehr, D. Krause-Jensen, N. Risgaard-Petersen, and B. R. Silliman. 2007. Alien macroalgae in Denmark – a broad-scale national perspective. Marine Biology Research 3:61-72.

Vitousek, P. M., C. M. D Antonio, L. L. Loope, and R. Westbrooks. 1996. Biological invasions as global environmental change. American Scientist 84:218-228.


Let’s Go Crabbing!

Nicole Doran, the Ohio State University


This is me driving the boat to one of our sampling sites, photo credit to Stevie Czwartacki

The problem: If you go to any seafood restaurant in Charleston, South Carolina, there is a good chance that you will see dishes with blue crab in it. Blue crab (Callinectes sapidus) are popular on the East Coast, especially in South Carolina, Maine and Maryland because of their salty-sweet flavor, especially the lump meat that is used for dishes such as crab cakes! Because of the high demand for blue crab meat, it is one of the top three commercial fisheries in South Carolina, so this little crab plays a big role in the South Carolina economy.Something that could help resource managers and fisheries in predicting the fate of the blue crab is looking at their life histories, or how they reproduce, mature and behave throughout their life cycle. Blue crabs spawn in the sea and larvae move into tidal creeks and estuaries, where the salinity (salt concentration) is lower because of freshwater input. These important ecosystems serve as a nursery where juvenile crabs feed, grow, and mature. Then something interesting happens; the females migrate away from the tidal creeks back into the sea to spawn (release their eggs) while the male crabs typically remain in the creeks to live out the remainder of their lives. This pattern has been observed in the fishery’s trawl data, which shows catches from the ocean are predominantly female.


A mature blue crab.  Photo:(http://www.dnr.sc.gov/marine/pub/ seascience/bluecrab.html)

The question I will be trying to answer is if male and female blue crabs tolerate high and low salinities differently. For my experiment, I collected juvenile crabs from creeks using trawl nets and crab pots, and will place the crabs in a laboratory setting in two different salinity conditions. Previous research has shown blue crabs grow at greater rates in high salinity, but not much research has been done on the physiological differences between males and females.

This work is important to the blue crab fisheries because local fishers and businesses rely on this crab as income and a food source. It is predicted that climate change will alter the environmental conditions in Charleston’s creeks and harbor, but it is uncertain how this could potentially affect the blue crab populations. By studying the conditions blue crabs are able to tolerate, resource managers can better understand how blue crab populations will respond to future environmental changes.


Me on a boat surrounded by the crab pots used by the DNR and fishers to catch blue crab! Photo credit to Stevie Czwartacki


I would like to acknowledge and thank the Fort Johnson REU program and NSF DBI-1757899 for making this research possible, the South Carolina Department of Natural Resources, Jeff Brunson, Stevie Czwartacki, and my mentor Dr. Michael Kendrick.


Archambault, J.A., Wenner, E.L., and Whitaker, J.D. 1990. Life history and abundance of blue crab, Callinectes sapidus Rathbun, at Charleston Harbor, South Carolina. Bulletin of Marine Science. 46(1): 145-158.

Cadman, Linda R. and Weinstein, Michael P. 1988. Effects of temperature and salinity on the growth of laboratory-reared juvenile blue crabs Callinectes sapidus Rathbun.  Exp. Mar. Biol. Ecol. 121: 193-207.

Mense, David J. and Wenner, Elizabeth L. 1989. Distribution and abundance of early life history stages of the blue crab, Callinectes sapidus, in tidal marsh creeks near Charleston, South Carolina. Estuaries. 12: 157-168.

Tagatz, Marlin E. 1968. Growth of juvenile blue crabs, Callinectes sapidus Rathbun, in the St. Johns River, Florida. Fishery Bulletin. 67: 281-288.