Gracilaria: New Intruder Weeding Through Charleston

Ana Silverio, The University of Texas at Austin

The Problem: Invasive species are animals that enter a new habitat away from their own home and are known for usually bringing about negative effects on natives in the area. Invasive species thrive in new environments when they can adapt to local conditions, and cause troubles in the way it works. With their usual predators not around, chaos can erupt, as they take away from some resources from the animals who call this habitat home (Albins et al 2015). Gracilaria vermiculophylla is a type of seaweed but also an invasive species from Asia and first seen on the Virginia coast. Although it is an invasive species, this seaweed seems to be singing a different song than usual (Nyberg et al 2009). Since it was first seen on the beaches of North America, it has taken a different role by providing a new habitat to local fishes. Gracilaria vermiculophylla is a dark brownish red seaweed with tangled strands that brush up against anything wading through the shallow water. Perfect for smaller fish to hide in. Although this seaweed seems to be bringing good things to the fishes not much is understood about what life was like for them under the waters of Charleston before our new stranger came about so we can’t comment on that part of the story. On the other hand, an interaction is indeed unfolding before our eyes and the story behind our new visitor is a bit fishier than one may think.

Example of a sample site: sparse patch of Gracilaria vermiculophylla on Grice Beach.
Photo taken by: Norma Salcedo

Gracilaria vermiculophylla is hard to miss on the shorelines of Charleston, it can be found in patches when the tide dwindles or on the seafloor. Its branches provide an ideal habitat along with a hiding space for juvenile fish during their vital first years of life and increases their numbers (Munari et al 2015). The preservation of these fishes during their early life stages is important to maintaining a healthy food web that keeps marine life afloat. Food is energy and energy is moved up to some of the biggest fisheries in this country from the very bottom of the smallest animals. It is important to know how the bigger fish’s food source is interacting with its habitat to make sure it’s healthy. Understanding how the interaction is working is a key factor in creating conservation plans and maintaining the ecosystem in good health.

Dense patch of Gracilaria vermiculophylla.
Photo taken by: Norma Salcedo

This summer, my research focus is on untangling Gracilaria vermiculophylla’s ecological relationships with these small fishes for a better understanding how diverse life is underwater. Replicating a design from the past two summers, I am curious to see the differences in diversity and abundances based on different patches of seaweed and if body size plays a significant role. Will more seaweed correlate with more diversity? The past two summers revealed some common patterns between fish diversity and patterns of seaweed patches but also some surprising differences between the two field seasons. Will we have a tie breaker this summer? Stay tuned to find out!


Special thanks to my mentor, Dr. Harold for his support and guidance throughout this project. Also, to Dr. Podolsky and Grice Marine Lab for giving me the opportunity to conduct this research. This project is supported by the Fort Johnson REU program, NSF DBI-1757899.


References

 Albins MA (2015) Invasive Pacific lionfish Pterois volitans reduce abundance and species richness of native Bahamian coral-reef fishes. Mar Ecol Prog Ser 522:231-243. 

Munari, C., N. Bocchi, and M. Mistri. “Epifauna associated to the introducedGracilaria vermiculophylla (Rhodophyta; Florideophyceae: Gracilariales) and comparison with the nativeUlva rigida(Chlorophyta; Ulvophyceae: Ulvales) in an Adriatic lagoon.” Italian Journal of Zoology 82.3 (2015): 436-445.

Nyberg, C. D., M. S. Thomsen, and I. Wallentinus. “Flora and fauna associated with the introduced red algaGracilaria vermiculophylla.” European Journal of Phycology 44.3 (2009): 395-403.

Shewanella: Sneaky Sulfur Cyclers?

Katherine Mateos, Carleton College

Like Shewanella, I too thrive at cold temperatures!

Life can survive almost anywhere! From hot pools on volcanoes to beneath ice-cold glaciers, pretty much all of the inhabitants in these hostile environments are so small that you cannot see them with your bare eye. These extremophiles, as they are often called, include tiny single-celled microbes—bacteria and archaea. By studying tiny microbes we can answer big questions: How did life begin on Earth?  How can we find life on other planets? How will our planet respond to its changing climate?

Outflow of Blood Falls on the Taylor Glacier. Image credit: Dr. Jill Mikucki.

This summer, I am working with one of these extremophiles, a type of bacteria separated out from a sample from Blood Falls, Antarctica. This lake is a pool of brine (very salty water) covered by more than 150 feet of ice from the Taylor Glacier. Blood Falls gets its name from the bright red stain that the brine leaves on the Taylor glacier as it leaks out from beneath the glacier. As you would expect, this location is cold and dark, but the chemicals in the brine are what truly make this ecosystem extreme. For one, Blood Falls is super salty, over twice as salty as the ocean. Most water has oxygen trapped within it, but Blood Falls has very little. Two important chemicals are also found in unusually high quantities: iron and sulfur.

Electron Microscope image of Shewanella BF02. Image credit: Bruce Boles.

The bacteria that I am studying makes good use of the iron in this environment. Like a battery produces energy from a variety of chemical reactions, Shewanella (strain BF02) gets most of its energy by harnessing the energy that is released when one chemical form of iron changes to another. However, there might be another source of energy Shewanella can live off of—perhaps a chemical that contains sulfur. Sulfur is one of the most common elements on earth, found in pesticides, foods, and in humans. Sulfur can form compounds with other common elements including hydrogen, carbon, and oxygen. Some of these chemicals, known as volatile organic sulfur compounds (VOSCs), easily evaporate into our atmosphere and affect our environment. We want to know if the Shewanella are creating these VOSCs, and if they do, what chemicals the Shewanella turn into VOSCs.

The strain of Shewanella that I am studying is from an extreme ecosystem but similar Shewanella are found throughout many ocean ecosystems. We can treat Blood Falls as a model to learn about the way that our oceans will affect our environment.  Even though Shewanella are too small to see with your bare eyes, figuring out what compounds they break down can help us understand the future of the environment around the world.

Thank you to my mentor, Dr. Peter A. Lee, and our collaborators, Dr. Jill Mikucki and Abigail Jarratt, for their guidance in the research process. This project is supported by the Fort Johnson REU Program, NSF DBI-1757899.

References

Mikucki, J. A. et al. A contemporary microbially maintained subglacial ferrous ‘ocean’. Science 324, 397–400 (2009).

Sievert, S. M., Kiene, R. P. & Schulz-Vogt, H. N. The sulfur cycle. Oceanography 20, 117–123 (2007).

Crikey! What’s in the Water?

Julianna Duran, Virginia Tech

1B7047D7-DD01-4D65-B081-9D809AC07271The Problem: South Africa is home to some of the most extraordinary wildlife and culture. This diverse ecotourism plays a major role in their economy and conservation efforts.

Crocodile

Nile Crocodile (Photo credit: Darren Poke)

The Olifants River System in the Mpumalanga Province is a large source of water that provides a habitat for several species. Over the last 30 years in this region, there have been dramatic declines of Nile Crocodile (Crocodylus niloticus), fish, and waterfowl.

The cause of this is a disease called Pansteatitis. It is hypothesized that contaminants from coal mining and agriculture contributed to the emergence of the disease. Invasive species and the stagnant water may also be enhancing the intensity of its effects.

Pansteatitis is an inflammatory disease that affects the lipids, or fats, of an animal. The fats become tough which cause pain and a reduction in mobility that can make the species easier prey or unable to hunt for food.

Mozambique Tilapia (Oreochromis mossambicus) have been frequently diagnosed with pansteatitis and maintain a large population size. These characteristics make them a perfect model organism to use for researching pansteatitis – which is why they were selected for my project. I will be analyzing muscle tissue samples of these fish to compare the fatty acid profiles between healthy and diseased specimen; infected Nile Crocodile muscle will also be key in understanding how pansteatitis affects different organisms.

OLYMPUS DIGITAL CAMERA

Mozambique Tilapia – Photo taken from John Snow

It is important that we study Mozambique Tilapia to influence management efforts for top predators like Nile Crocodile, whose presence and actions impact the food web. In addition, tilapia and other fish are harvested and I want to ensure that any diseased fish caught are safe to eat. Although there have been no studies that have found whether or not this disease can directly affect humans, I hope that my study can give us an indication of the indirect human health risks.

Research Questions

  1. What is the difference in Fatty Acid Profiles between healthy and diseased Mozambique Tilapia?
  2. What is the difference between diseased Mozambique Tilapia and Nile Crocodile?
  3. What lipids are most affected by Pansteatitis?

This Summer, I will be investigating these questions and reporting back my findings. To find more information on the topics check out these links:

Blood Chemistry of Pansteatitis-Affected Tilapia

Life History of Mozambique Tilapia

Life History of Nile Crocodile


Supported by the Fort Johnson REU Program (NSF DBI-1757899), Dr. Mike Napolitano, Dr. John Bowden, The College of Charleston, NOAA, and NIST. 


References:

Bowden, J., Cantu, T., Chapman, R., Somerville, S., Guillette, M., Botha, H., Hoffman, A., Luus-Powell, W., Smit, W., Lebepe, J., Myburgh, J., Govender, D., Tucker, J., Boggs, A. and Guillette, L. (2016). Predictive Blood Chemistry Parameters for Pansteatitis-Affected Mozambique Tilapia (Oreochromis mossambicus). PLOS ONE, 11(4), p.e0153874.

Poke, D. 5 Interesting Facts About Nile Crocodiles. https://haydensanimalfacts.com/2015/03/04/5-interesting-facts-about-nile-crocodiles/ (accessed Jun 27, 2019).

Snow, J. Mozambique Tilapia. https://www.mexican-fish.com/mozambique-tilapia/ (accessed Jun 17, 2019).

2019 Fort Johnson REU Program!

Posts above this one will be from our new REU interns: Kelsey Coates, Samuel Daughenbaugh, Jules Duran, Jackson Eberwein, Lilia Garcia, Katherine Mateos, Jordan Penn, Carolina Rios, Ana Silverio, & Pressley Wilson.  The interns will be posting about the problem they are studying and the research approach they are taking to address it.