Invasive Species: Friend or Foe

Melanie Herrera,  University of Maryland – College Park

Invasive species…. Haunting, domineering, and downright evil. Or are they? Unlike the infamous Zebra Mussels, dominating the Great Lakes, or Fire Ants, constantly wreaking havoc, Gracilaria Vermiculophylla, are giving invasive species a good name. Don’t get me wrong, invasive species infuriate me just as much as the next guy; but Dr. Tony Harold and I are here to draw out the benefits of this invasive sea grass to baby fish.

Unlike the native, simpler sea grass previously occupying Charleston Harbor, Gracilaria is characterized by coarse branching structures that appeal to many species of fish as protective homes. We are particularly interested in fishes in the larval and juvenile stages (the young ones) that associate with these complex habitats. Having access to more protective sea grass, such as this invasive, in these vulnerable life stages can help determine how many of these little guys make it into adulthood. Similar macro-algae to Gracilaria, such as seaweeds, have been known to be preferable hideouts for larvae and juveniles, reducing the pressures of predation. Since Gracilaria is on the rise in our local estuary, the Charleston Harbor, it’s important to find out the role they play in keeping our fish alive and well.

Our project is designed to better understand the level of association of local fish such as Gobies, Atlantic Menhaden, Atlantic Silversides, and other estuary-occupying fishes, with Gracilaria. We will compare abundance and distribution of young fish in dense patches of Gracilaria to sparse patches. Maybe these young fishes prefer the familiarity that native sea grass and open water brings. Or maybe Gracilaria’s “new and improved” design is too advantageous to resist. After we figure this out, we can go on sustainably managing local fish critical to commercial and recreational use and condemning the rest of the invasive species.

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An example of a collection site characterized as a “dense” habitat of Graclaria vermiculophylla.  Photo Credit: Melanie Herrera

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An example of a collection site characterized as a “sparse” habitat of Gracilaria vermiculophylla. Photo Credit: Melanie Herrera

 

Thank you so much to my mentor Dr. Tony Harold and his lab for his advice and guidance. Thank you to Mary Ann McBrayer for helping me facilitate this project. This research is funded through the National Science Foundation and College of Charleston’s Grice Marine Lab.

 

Works Cited

Munari, N. Bocchi & M. Mistri (2015) Epifauna associated to the introduced Gracilaria vermiculophylla (Rhodophyta; Florideophyceae: Gracilariales) and comparison with the native Ulva rigida (Chlorophyta; Ulvophyceae: Ulvales) in an Adriatic lagoon, Italian Journal of Zoology, 82:3, 436-445, DOI: 10.1080/11250003.2015.1020349

 

Parasitic Kudoa inornata causes muscle deterioration in spotted seatrout

Sierra Duca, Goucher College

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This summer I am working at the South Carolina Department of Natural Resources at Fort Johnson under the mentorship of Dr. McElroy and Dr. Isaure de Buron. Being part of an REU program, I am looking forward to gaining some research experience and learning more about career possibilities in the biological sciences. In terms of my research, I am researching the effects of a microscopic parasite, Kudoa inornata, on spotted sea trout (see image below).

Seatrout

Photo source: http://www.kayaking-north-america.com

There are many Kudoa species that infect host fish worldwide. Several of the Kudoa parasites have spores (known as myxospores; see image below) that proliferate inside of the muscle fibers of the host fish (Harrel et al. 1985). In some cases the  parasites wreak havoc on the quality of the meat after the fish dies. For example, infected fish may have unsightly cysts or decreased meat quality (Moran et al.), both of which are unappealing to consumers. Don’t worry, the majority of Kudoa infected fish are not directly harmful if consumed by humans; however, if the deterioration of the muscle tissue is accelerated, like any meat, the quality will decrease sooner as compared to uninfected fish. This process of muscle deterioration is what I am studying with K. inornata infected spotted seatrout. I am looking at the rates of this deterioration during various time frames, from 0 to 6 days after the fish dies, in order to discern if there is a relationship between parasite presence in spotted seatrout and muscle softness.  Ultimately, this research can be used to better understand the biology of K. inornata and to determine the best time frame to consume infected spotted seatrout.

picc     Individual spores of Kudoa inornata (Photo source: Dyková et al., 2009).

Literature Cited

Dyková I, de Buron I, Fiala I, Roumillat WA (2009) Kudoa inornata sp. n. (Myxosporea: Multivalvulida) from the skeletal muscles of Cynoscion nebulosus (Teleostei: Sciaenidae). Folia Parasitology 56: 91-98

Harrel LW, Scott TM (1985) Kudoa thyrsitis (Gilchrist) (Myxosporea: Multivalvulida) in Atlantic salmon, Salmo salar L. Journal of Fish Diseases 8: 329-332

Moran JDW, Whitaker DJ, Kent ML (1999) A review of the myxosporean genus Kudoa Meglitsch, 1947, and its impact on the international aquaculture industry and commercial fisheries. Aquaculture 172: 163-196

Acknowledgments

The Fort Johnson REU Program is funded by the National Science Foundation. This research is made possible through the mentorship of Dr. Eric McElroy and Dr. Isaure de Buron.  In addition, I would like to thank the College of Charleston and the South Carolina Department of Natural Resources for providing the help and facilities necessary for my project.