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.

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