How did UV light and climate change stressors affect oil toxicity in grass shrimp larvae?

Cheldina Jean, American University


Collecting samples at Leadenwah Creek (Photo credit: Katy Chung)

Findings: In my first post I outlined the uniqueness of estuaries, the importance of grass shrimp as a prey species and in the food chain, and how environmental conditions such as UV light, salinity and temperature can affect the toxicity of crude oil in the environment. The objective of my research this summer was to determine the effect of UV light and climate stressors such as temperature and salinity on oil toxicity in grass shrimp larvae. We hypothesized that:

1) UV light would increase the toxicity of oil to the grass shrimp larvae,

2) oil combined with high temperature and low salinity would increase the toxicity of oil and mortality of the larvae, and

3) combining UV light, oil, and these climate change stressors would further increase the toxicity of oil to the larvae, leading to greater mortality. 

In my second post, I highlighted the methods we would use to test these hypotheses under combinations of different environmental conditions:  oil or no oil, UV or no-UV light, salinities of 10 ppt, 20 ppt, and 30 ppt, and temperatures of 32 degrees Celsius and 25 degrees Celsius. 

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Creating the HEWAF (phot credit: Katy Chung)

Over the ten week period, our results showed that UV light alone altered the chemical composition of the oil as a HEWAF leading to greater toxicity to the larvae in all of the tests. The lower salinity of 10 ppt and the higher temperature of 32 degrees Celsius were the most stressful climate conditions for larval grass shrimp in both the UV and non UV conditions. The high salinity of 30 ppt did not significantly alter oil toxicity. Combining UV light with high temperature and low salinity significantly altered the toxicity of oil and further increased the mortality of larval grass shrimp.

In conclusion, understanding how climate change stressors such as salinity, temperature, and UV light modify the toxicity of oil to estuarine species will help resource managers predict environmental change and recovery following an oil spill. Some future directions of this research include testing earlier grass shrimp life stages, such as embryos, and other estuarine larval organisms under these conditions.

I have been interested in environmental toxicology ever since I was in middle school, and this summer I was finally able to finally immerse myself in toxicological research. I am glad that I was able to partake in this research experience because it made me realize that this is a field that I am interested in pursuing. I got to meet and work with a lot of great people and I gained valuable skills in research, and science communication. I am looking forward to my next research experience and what the future holds for me!

grass shrimp larvae gif

grass shrimp larvae being released from female grass shrimp. (Credit:

I can not thank my awesome and supportive mentors Marie DeLorenzo and Katy Chung enough for helping me with my research project. Working with them and everyone at NOAA’s National Centers for Coastal Ocean Science was an amazing opportunity. This project is supported by the Fort Johnson REU Program, NSF DBI: 1757899.

Haloarchaea: Shifting tides

Ben Farmer, University of Kentucky


Credit: Bob Podolsky. This was from an outreach trip to Magnolia Plantation & Gardens for Ladybug Release day. Getting to show kids (and adults!) sea creatures was a fun break from research.

Findings: After 10 quick weeks, my research on extremophiles at College of Charleston is now coming to a close. In my previous post, I described the methodology that I used in the Rhodes lab to research a species of haloarchaea, Haloferax sulfurifontis. Haloarchaea are extremophiles that thrive in excessively saline conditions like the Great Salt Lake in Utah.

Haloferax is fascinating because it can not only survive, but grow, in anywhere between 6% and 37% salinity. That is from ~2 to ~10 times the average salinity of sea water! This makes it a great model for understanding how halophiles might acclimate in real time to the salt concentration around them.

The way we chose to do this over the summer was by analyzing the abundance of particular tRNA in Haloferax. The results were pretty exciting, and while I cannot touch on anything too specific, we definitely found trends. Some of these trends were in line with what we expected to see, while some where quite the opposite. Such is science. The main takeaway is that whether we produced results we “wanted” to see or not, the results were exciting on their own and told us meaningful information about important environmental adaptations in extremophiles.


A flask containing culture of haloarchaea. The grapefruit-tinged color is caused by the pigments found in the millions of haloarchaea cells growing in the hypersaline media solution.

I came into this summer wanting to gain experience in molecular techniques. I previously worked with corals in the Caribbean, and really wanted to know more about what was going on at the molecular level in things like coral disease. While I focused on archaea this summer, I gained a wealth of knowledge pertaining to microbiological techniques, working with bioinformatics, and interpreting academic articles on projects that use these techniques. After this summer I am newly invigorated to take what I have learned in the lab, and apply it to my passion for coral reef research.

Lastly, I want to extend my thanks to Dr. Rhodes for his ever patient mentorship, as well as everyone involved with the lab. My labmates, Isabella and Lilyana, were committed to collaboration wherever possible and it made life in the lab a breeze. Also, Dr. Geslain provided extensive knowledge of tRNA as well as use of his equipment, for which I am very grateful. Lastly, I would like to thank everyone at the Fort Johnson REU program for putting together such a great research opportunity and having us for the summer!


This project is funded through the National Science Foundation and supported by the Fort Johnson REU Program, NSF DBI- 1757899.


Gracilaria: A dynamic habitat

Nick Partington, St. Olaf College

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Findings: In my previous post, I described the methods we would be taking this summer to explore how the biodiversity of fishes differ among dense and sparse patches of the invasive alga Gracilaria vermiculophylla. We followed these methods, and we produced some interesting results!

We finally sorted and identified all of the fishes we collected from our samples this summer, and were able to measure the biodiversity between dense and sparse habitats. In particular, we were interested in four measurements of biodiversity. The first, abundance, is simply the overall number of fishes collected from each habitat type. The second, species evenness, measures how evenly individual fishes


Some of the fishes we collected this summer, separated by species and sample.

are distributed among the different species collected in each habitat type. Finally, diversity took into account species richness, which counts the total number of species collected, and the Simpson’s Diversity Index, which quantifies diversity based on the number of species and the relative abundance of each of those species.

These measurements provided us with some interesting results. In the end, we collected a greater abundance of individuals in sparse sites than in dense sites. We also saw both greater species evenness and greater species richness in dense sites. Additionally, the Simpson’s Diversity Index showed a greater diversity of fishes in dense sites.

As I mentioned, abundance of individuals and species richness were both calculated by simply counting the overall number of individuals and species, respectively, collected in each site. Species evenness, on the other hand, required a bit more analysis. Figure 1 shows rank abundance curves for both sparse and dense patches of G. vermiculophylla. These curves tell us how evenly individuals are distributed among the species collected from each site. For each habitat type, species are ranked from 1 to 10 in decreasing order of abundance. That rank is then compared with the abundance of each species. The slope of the resulting line is what we are interested in. Basically, the flatter the line, the greater the species evenness. In our analysis, the line representing dense sites had a flatter slope, signaling greater species evenness in dense sites than in sparse sites.

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Figure 1. Rank abundance curves for both dense and sparse habitats. The slope of the curve representing dense habitats is closer to 0, indicating greater species evenness in those sites.

As I mentioned, overall we found a greater abundance of individual fishes in sparse sites, while we had greater species evenness, species richness, and diversity in dense sites. These differences between sites are very interesting in themselves. But what is even more interesting is that these results are the complete opposite of what was concluded after this same study was conducted last summer. Therefore, there must be some factor(s) that changed between these two studies. We’re not exactly sure what these factors are, but nonetheless, this highlights the importance of long term studies, as well as the importance of continuing this study to see how these trends in biodiversity change and pan out in the long run. I think a very interesting takeaway from this project is that invasive species, like G. vermiculohylla, can potentially provide benefits and sustain biodiversity in ecosystems here in Charleston and throughout the world.

Special thanks to Tony Harold and Mary Ann Taylor for their 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.

9,000 Larvae Later…

Jaclyn Caruso, Salem State University

Me UrchinFindings: In my previous post, I talked about how counting larval stages and measuring their skeletons could help us determine the lethal and sublethal effects of preservatives used in cosmetics and other personal care products on development. What we found was pretty surprising.

After two days of development in normal conditions, sea urchin larvae should be in the pluteus stage and have 2 or 4 arms. The arms are important because they are surrounded by bands of cilia that help the larva swim and feed. In the controls and at the lowest concentrations that we tested (0.1, 1, and 10 parts per million), the majority of the larvae successfully reached this stage. However, things got interesting at about 32 ppm.

We found that at concentrations at and above 32 ppm, the larvae generally grew shorter arms, had a smaller body size, and were more asymmetric. Any of these abnormalities could potentially have fatal consequences for the larvae. We also found that at high enough concentrations of the preservatives, development will fail completely. At concentrations of 1000 ppm, almost 100% of the fertilized eggs that we added to the jars didn’t develop past the early cleavage stages. This means that development was stopped almost instantly.

If you remember back to my first post, we wanted to test how parabens compared to the newer alternatives they were replaced with. Of the three preservatives we tested, the paraben caused changes in growth and failure of development at the lowest concentrations. The other two preservatives fared slightly better, suggesting that the personal care products industry may have made a good decision by switching. However, because we saw harmful effects in all three preservatives, we can’t say that they are completely safe for marine life at these concentrations.

This summer has taught me a ton about scientific research. I always expected it to require a lot of time, patience, and dedication, and my expectations were absolutely confirmed. In total, we counted and categorized 8,919 larvae and measured 2,224. That’s a lot of long hours at the microscope, and a lot of data to analyze. But, our results were definitely worth it, and I’m greatly looking forward to my next research experience!

Larval Stages

Left: normal preserved plutei in the 4- or 2-arm stage. Right: abnormal preserved individuals with incorrectly shaped skeletons or at early stages of development. Jaclyn Caruso, 2018


Thank you to Dr. Bob Podolsky (CofC) for his mentorship, Dr. Cheryl Woodley (NOAA) for providing her procedures and resources, and Pete Meier (CofC) for teaching me the ropes of setting up aquaria. This project is supported by the Fort Johnson REU Program, NSF DBI-1757899.

A Summer of Growth

Nicole Doran, The Ohio State University

Findings: This summer I studied growth rates of male and female juvenile blue crab in different salinity treatments to determine if sex or salinity affects growth rates. For background information refer to my previous blog post discussing the problem, and my methods are discussed in another previous post. The data we collected on the individual crabs in each treatment were analyzed in a number of ways to compare the growth of males and females in both high and low salinity.

The first way we analyzed growth rate was by calculating a body volume index using the crabs’ body measurements (volume= length x width x depth). Their initial volume was compared to their final volume to find the percent change in size. The percent change was averaged for males and females in each tank, and the average of all of the low salinity males, females, and high salinity males and females is shown in the bar graph below.



As you can see, there are greater growth rates for both males and females in low salinity. An ANOVA was run on this data and confirmed that the effects of salinity were significant. However, sex was not a significant factor. This does not support my hypothesis, as previous studies have shown greater growth rates in high salinity. Before discussing why this might be, let’s look at the wet weight data. Growth rate using wet mass were calculated in a similar fashion as the body volume index using the crabs’ initial and final weights, and averaging them for each tank. The averages for males and females in both treatments are shown below, and you’ll notice that it shows a slightly different result.



ANOVA results of this data show that neither sex nor salinity significantly affected growth rates, but the interactions between sex and salinity were significant. Post-hoc analysis showed that there were marginally significant differences in the growth rates of males in low salinity and males in high salinity. This is more similar to the trend I originally hypothesized.

So what did we learn from all of this? This study indicated that male blue crab grow at slightly greater rates in low salinity than high salinity, and that overall blue crab grew faster in low salinity. While this conflict with findings from previous studies that have found the opposite, there are some studies that have noted blue crab gained more soft tissue mass and molted more rapidly in low salinity. This same study also did not see a difference in the body size change after molting despite this greater weight increase, so I think that might be what we saw here since the body size and wet weight results differed slightly. This may not have negative implications on the blue crab seem to grow well in a wide range of conditions, but climate change may increase salinity in estuaries. This may affect the range of habitat males and females use since it seems males prefer low salinity, or somehow affect the growth of juvenile male crabs. While this may not have significant effects on population abundance, it is still useful for resource managers to know what habitats blue crab are utilizing and how the population may respond in the future. This way they can effectively assess potential management actions for the blue crab fishery so it successful for years to come!

The pictures above are me doing field work! Picture credit: 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 and Stevie Czwartacki for their help in the field and sharing their knowledge with me and my mentor Dr. Michael Kendrick for his guidance and support this summer.

Getting warmer…

Kaylie Anne Costa, University of Miami

IMG_6879Findings: In my previous post, I outlined how lipidomics and metabolomics would be used with mass spectrometry to study changes in the lipids and metabolites in manatee plasma in response to cold stress syndrome. The purpose of this study to provide deeper understanding how cold stress syndrome impacts Florida manatees

Our original research question was: Can changes in the lipidome and metabolome of plasma samples of Florida manatees be seen in response to CSS? Although the metabolomics data is still being processed, lipidomics has already shown promising results. Through our research we have found an interesting correlation between an

individual having a plasma Serum Amyloid A (SAA) value outside the healthy range and changes seen in their plasma lipidome. SAA is an acute phase protein produced in response to inflammation. When comparing the healthy manatee plasma samples to the CSS plasma samples with a Serum Amyloid A value greater than 50 µg/mL, we have found 81 lipids that differ significantly between plasma samples from healthy manatees and manatees with cold stress syndrome (Figure 1).


Figure 1: Percentages of each lipid category out of the 81 total significant lipids that differed between CSS and healthy manatees

Our results indicate that the plasma lipidome of Florida manatees can differ as a result of cold stress syndrome. Now the next question is: what does this difference mean in context of manatees’ physiological response to cold stress syndrome?

This question is harder to answer, but we hope to be able to trace these lipids back to specific biological pathways that are altered by CSS. When the analysis of the metabolomic data is complete, we will have more pieces to the puzzle that may allow us to hone in on specific biological pathways affected by CSS that produce a change in both the lipidome and metabolome.

This pilot study will hopefully pave the way for future studies that will help protect this threatened species and conserve them as a sentinel species for studying how environmental changes will impact human health for the future.

This summer I have gained crucial research experience by using advanced techniques of analytical chemistry to address a threat to health in the marine environment. Through this REU program, I have learned about the diverse ecosystems in the Charleston area as well as the history that makes Charleston such a unique place. I would recommend the Fort Johnson REU program to any student looking for an opportunity to further their marine science education through research.

I cannot say thank you enough to my mentors Dr. John Bowden and Dr. Mike Napolitano. Their knowledge and eagerness to guide me through this process made this project possible. I would also like to thank the College of Charleston’s Grice Marine Lab for hosting the Fort Johnson REU program, National Science Foundation (NSF DBI-1757899)for funding, and our collaborators with the USGS Sirenia project for supplying the samples used in this study.


Harr, K., Harvey, J., Bonde, R., Murphy, D., Lowe, M., Menchaca, M., … & Francis-Floyd, R. (2006). Comparison of methods used to diagnose generalized inflammatory disease in manatees (Trichechus manatus latirostris). Journal of Zoo and Wildlife Medicine37(2), 151-159.


BMA, our potential superheroes…pending

Connor Graham, Francis Marion University


Findings: At the beginning of this summer my mentors and I had specific objectives and questions we wanted to answer regarding the biogeography of benthic microalgae and of course like any experimental hypotheses, things change. Our main objective was to identify the community structure on five barrier islands on South Carolina’s coast and see if there were differences. If there were differences were they because of geographic distance or environmental factors?  As the summer progressed our questions changed slightly to look more at community biomass instead. Of course our questions link back to the larger picture of using these diatoms as bioindicators for environmental health.

Community structure is composed of two main components: biomass and DNA composition. Biomass is the mass of the organisms present in a given area. Even though we collected samples for DNA, we had an allotted time which only allowed for analyzation of the biomass samples which were chlorophyll a. So, now our main questions were: Are there differences in community biomass among islands? Are those differences due to geographic distance or environmental factors like water temperature, nutrients, wind, pressure and so many more.

Based on the results from the data we have, biomass does indeed differ among islands, geographic distance is not the reason, but instead a few environmental factors. Those significant environmental factors are located in the table below. Still taking in account that we have pending analysis for DNA composition, nutrients and grain size, our original questions could be supported quite differently.


The result of an ANOVA test which showed biomass differences among islands. The p-value was less than 0.0001.




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This p-value of 0.439 shows that Geographic distance is not correlated with community BMA biomass.

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These are the significant environmental factors that correlate with BMA biomass, with water temperature being the most significant with a p-value of 0.001.

However, if we do see that community structure is not affected by the differences in locations, then potentially there is no dispersal limitation on our microbes. Also, if community structure is also impacted by environmental like biomass, then we could potentially use this to measure bioindication by adding in a new factor.

As of now, we are not sure if diatoms can be used as bioindicators, and if they are the superheroes we need. However, we do know that more research is needed to find out and until then our great state awaits its savior.


A picture of me covered in mud at Hunting Island after a day of sampling. Photo: Max Cook


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.