Not all superheroes wear capes!

Connor Graham, Francis Marion University

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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?

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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.

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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.

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

Acknowledgments

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.

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Shrimp kabob, shrimp gumbo…shrimp sickness?

 

Alessandra Jimenez, Whitworth University

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Are you a fan of shrimp? You’re not the only one – billions of people around the world depend on shrimp fisheries and aquaculture for this wonderful source of food. Other predators in the sea rely on shrimp for their daily meals. Here’s the catch: shrimp may not last long enough to make it to your plate. Like us and other animals, crustaceans in general have to deal with so many obstacles that threaten their survival. One obstacle that is not often thought about is bacterial infection. Did you know that seawater is literally teeming with hundreds of millions of bacteria? The only way a shrimp can make it is by using its immune response – the “quick, potent, and effective” way of defending against a huge, microscopic army! Sounds like the perfect shield, right?

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Shrimp is a common food source for many people. @Leslie Fink

Turns out that, like everything else in the science world, immunity comes at a big cost. It has been recently discovered that the immune response in crabs and shrimp against bacteria actually has a bad side effect: metabolic depression. In fact, the way the shrimp gets rid of bacteria in its bloodstream is by moving the bacteria to the gills, where it gets lodged and stays there for quite some time. The consequence? The lodged bacteria block blood flow through the gills, and the shrimp can’t get enough oxygen from the water. (Want to learn more? Click here)

Ouch, talk about a double whammy – fighting sickness plus oxygen blockage. One basic question comes to mind: can the shrimp still do what it needs to do while under such metabolic stress? This is where I come in. This summer, I am working under Dr. Karen Burnett in Hollings Marine Laboratory as an intern through the Research Experience for Undergraduates (REU) program in marine biology. We will be testing whether or not a shrimp’s immune response to a common bacteria affects its ability to perform daily activities. The activity of interest is called ‘tail-flipping’ (fancy name: caridoid escape reaction. Want to learn more? Click here)This really fast, reflex-like action needs to be in top shape for the shrimp to survive from predator attacks and to help it during feeding time.

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Also known as the ‘tail-flip’ reaction, this response is a shrimp’s primary means of escape. @Uwe Kils

The shrimp species of interest is Farfantepenaeus aztecus, or ‘Atlantic brown shrimp’. This fella is a familiar catch for fishermen throughout the Southeastern US and the Gulf of Mexico. This is the first time that a study like this is going to be done on a wild shrimp species in general, let alone this specific type!

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Farfantepenaeus aztecus, aka ‘Atlantic brown shrimp’. @Virginia Living Museum

So, can an immune response impact tail-flipping in wild shrimp? If ‘yes’, would the potentially handicapped shrimp be able to survive in its natural environment? We will soon find out!

Happy shrimping!

Alessandra Jimenez

REFERENCES:

Burnett, L. E., Holman, J. D., Jorgensen, D. D., Ikerd, J. L., & Burnett, K. G. (2006). Immune defense reduces respiratory fitness in Callinectes sapidus, the Atlantic blue crab. Biological Bulletin, 211(1), 50-57.

Fuhrman, J. A. (1999). Marine viruses and their biogeochemical and ecological effects. Nature, 399(6736), 541-548.

Latournerie, J.R., Gonzalez-Mora, I.D., Gomez-Aguirre, S.G., Estrada-Ortega, A.R., & Soto, L.A. (2011).                   Salinity, temperature, and seasonality effects on the metabolic rate of the brown shrimp Farfantepenaeus Aztecus (Ives, 1891) (Decapoda, Penaeidae) from the coastal Gulf of Mexico.Crustaceana 84(12-13), 1547-1560. doi: 10.1163/156854011X605738

Scholnick, D. A., Burnett, K. G., & Burnett, L. E. (2006). Impact of exposure to bacteria on metabolism in the penaeid shrimp Litopenaeus vannamei. Biological Bulletin, 211(1), 44-49.

Many thanks to College of Charleston for hosting my project, Dr. Karen Burnett and Hollings Marine Laboratory for guidance and work space, and NSF for funding the REU program.

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