1. A New System For Marking Hatchling Turtles
Using Visible Implant Elastomer (VIE)
Kaite P. Anderson, Nathan W. Byer, Ryan J. McGehee, and Teal M. Dimitrie
Department of Biological Sciences, Towson University, Towson, MD (contact:
Introduction
Methods
Results
A binary marking scheme was created, modeled after Ernst et al. (1974).
Each plastral scute assigned a number, allowing for each hatchling to have a unique number
This technique was applied to Northern Map Turtle hatchlings in
How Does VIE work?
Mix fluorescent colored component with a curing agent, 10 parts colored to 1 part curing agent
Use 0.3 cc syringe to inject small amount of mixed elastomer below the first layer of tissue of the appropriate plastral scutes; the mark should look like an uninterrupted line.
Mark will fade over time, but fluoresce under UV light.
Study of early life history stages can provide invaluable information for use in wildlife conservation
In long-lived vertebrates, such as turtles, data on survival rates, growth rates, and overall ecology of hatchlings and subadults are crucial for Population Viability Analysis (PVA)
This necessitates mark-recapture of hatchlings. Common techniques include:
Notching: Use of a triangular file or electric Dremel file to mark carapacial scutes
Drilling: Use of a standard electric drill to mark carapacial scutes
Branding: uses a surgical cauterizing tool on carapace or plastron
These techniques require shell or limb disfigurement and may not remain visible as the organism grows.
Recently, a technique known as Visible Implant Elastomer (VIE) has been used to mark small or hatchling turtles. There are several drawbacks to current VIE marking systems:
Use of multiple colors, increasing price of kits
Most techniques only apply cohort marks to groups of hatchlings; thus, no individual recognition
Herein, we present an intuitive, inexpensive, and easily recognizable marking system using Visible Implant Elastomer.
A total of 138 hatchling Northern Map Turtles were marked using Visible Implant Elastomer between 9 May 2012 and 29 June 2014
No hatchlings recaptured between seasons
Table 1. Individual hatchling captures for Columns refer to the total number of captures per season; the total number of individuals that were recaptured at least once in a season; and the total number of individuals that were recaptured multiple times per season. The bottom row accounts for total captures and recaptures to date.
Mark-recapture of one hatchling (#6) suggests rapid capacity for growth
Figure 2: :Adaptation of the Ernst et al. (1974) system for marking turtles. Numbering begins at the bottom of the plastron rather than the top due to scute size
Methods
Visible Implant Elastomer trial kit ($42) first purchased in 2012 from Northwest Marine Technologies, Inc.
Purchased for pilot mark-recapture study of Northern Map Turtle (Graptemys geographica) hatchlings
Part of a larger study of the ecology and management of a Northern Map Turtle population on the Susquehanna River in Maryland, below the Conowingo Dam
What does VIE look like?
Figure 4: Masses for Hatchling #6 from 9-May-12 and 25-July-12, indicating a total increase in mass of 568% or 42.0 g. 7
Conclusions
Total Mark: = 29
VIE represents an effective, potentially long-lasting method for marking hatchling and adult turtles
The low cost of a Northwest Marine Technologies trial VIE kit ($42) makes this marking technique applicable to most studies 2 20
Acknowledgments
Figure 1: At left: Northern Map Turtle female. At Right: Aerial photograph of Conowingo Dam and Susquehanna River in Maryland.
Funding provided by Exelon Corporation, Maryland DNR, and Maryland SHA
Many thanks to Port Deposit residents for their enthusiastic support of our work
Figure 3: Sample depiction of what Visible Implant Elastomer looks like when applied to a Northern Map Turtle hatchling. This turtle was marked #29.