APMS supported research investigates habitat level relationships with turtles, susceptibility to deadly disease

The APMS supports a great deal of student research through it’s many National and Regional research scholarships and awards.  One such award offered is the Philip M. Fields Scholarship, provided by the South Carolina Aquatic Plant Management Society.  The scholarship is awarded to a student who is researching an area related to the biology, ecology or management of aquatic plants in the Southeastern region.  Applications are evaluated on the basis of relevant test scores (ACT, SAT, GRE, etc.), high school and/or college grades, quality and relevance of course work or research, a proposed budget, information obtained from references, and other related information.

Mercurio, the 2012 award recipient in the field.

Mercurio, the 2012 award recipient, in the field.

In 2012, Albert Mercurio received the award to support his research on the susceptibilty of turtles to the naturally occurring toxin that causes Vacuolar Myelinopathy (discussed in last weeks blog), a neurologic syndrome associated with the invasive plant hydrilla (Hydrilla verticillata) that has recently only been known to affect waterbirds.  Through several trials, Mercurio fed turtles hydrilla colonized with the toxic cyanobacteria  in the laboratory and quickly realized that turtles were, in fact, susceptible to the toxin. Mercurio noticed that the turtles developed clinical signs, and the characteristic brain lesions used to diagnose the disease in birds, could also be found.

Turtle in laboratory feeding on hydrilla.

Turtle in laboratory feeding on hydrilla.

Discovering that there was a linkage of AVM to turtles, Mercurio and the group from UGA began a project to determine how turtles respond to hydrilla invasions in the wild. The team monitored turtle populations in five reservoirs throughout Georgia to answer this question and shed light on the broad linkage between the plants, the disease, and turtles. The group’s results indicated that painted turtles, common musk turtles (Sternotherus odoratus), and common snapping turtles (Chelydra serpentina) are more likely to be found as the density of hydrilla increases and that yellow bellied sliders (Trachemys scripta) are common throughout all microhabitat types. They believe it to be possible that in reservoirs with little native vegetation, turtles may use hydrilla as a resource for cover, forage, or to ambush prey.  The group points out that the negative effects of hydrilla, such as Vacuolar Myelinopathy may actually be superseded by these benefits. The group also has an alternative hypothesis that hydrilla could be creating an ecological trap, or a place that seems attractive to turtles but actually results in higher mortality rates.

Laboratory setup of turtle susceptibility experiment

Laboratory setup of turtle susceptibility experiment

The group from UGA, including Mercurio are planning more in depth studies of habitat use and abundance that could potentially confirm or deny these two competing hypotheses. Furthermore, it is currently unknown if turtles in these reservoirs would also respond positively to increases in native vegetation density, but relevant studies by the group suggest they would. If so, this work and subsequent investigations with similar outcomes would support aggressive hydrilla management that includes replacement or “revegetation” with native plants.

Turtles in a reservoir with dense hydrilla.

Turtles in a reservoir with dense hydrilla.

For more on the work being done at UGA, visit the groups website.

For information on how you can apply to the SCAPMS Philip M. Fields Scholarship, click here.

For information on scholarships in YOUR region, check each regional webpage here.

Stay tuned for more from the APMS Blog!

The APMS Blog is prepared by Dr. Brett Hartis, NC State University
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