Maryland Terrapin

Classroom Education Project:

Monitoring the Growth and Health of Diamondback Terrapins in Captivity – A Feeding Study… A hands-on science experience focusing on the diamondback terrapin and restoration efforts in the Chesapeake Bay

Project Summary:

            The diamondback terrapin is the focal point of a learning experience emphasizing life history, habitat, conservation, and scientific research.  The research objective of this project is to learn the effects of three different diets on terrapin growth.  The lesson plan describes basic terrapin biology, and provides a hands-on research exercise that will provide students the opportunity to become real scientists.

Year 1 Pilot: Seventh-grade students from select Eastern Shore middle schools learned about Maryland's state reptile, the Diamondback terrapin, and its importance in the Chesapeake Bay ecosystem through a research-based feeding study. Students were exposed to terrapin biology, conservation, life history and growth requirements. Students cared for newly hatched terrapins in their classroom while collecting bi-monthly growth data. Students were provided with additional hands-on terrapin conservation experience by participating in a field trip to Poplar Island where students released the terrapins they raised into the island's restored marshes.

Summary of Student Experience

             The students’ initial terrapin education experience begins when Horn Point Laboratory personnel visit the classroom and set up aquaria for the experiment.  The staff discusses with students their role in the care of the terrapins and an overview of the experiment.

            Students then visit Horn Point Laboratory and students learn more about the diamondback terrapin during a presentation that provides historical information about the diamondback terrapin, and information regarding prior research focused on the effects of temperature on the gender of hatchling terrapins.  Restoration efforts by the Army Corps of Engineers, Maryland Environmental Service, and Arlington Echo Outdoor Education Center are also highlighted.

            Diet effects on the growth of Diamondback terrapins are tested at Horn Point Laboratory and in each classroom.  The research exercise evaluates the effects of three diets: 35% protein/5% fat; 40% protein/10% fat; and 42% protein/16% fat  (Zeigler Bros., Inc Gardners, PA) on terrapin growth – weight and body size (carapace length, plastron length, width and height).

            While on their visit at Horn Point Laboratory, students perform the same procedure scientists do when diamondback terrapins are brought to us from the Maryland Environmental Service (MES).  MES is responsible for the collection and hatching of terrapin eggs on Poplar Island, and provides us with the terrapins for this experiment.  The young hatchlings, which have been given identification markings by MES staff, are divided into small groups in specialized holding tanks where they remain for the duration of the experiment.

            Incorporating the scientific method, students develop an appropriate problem and formulate a hypothesis based on the experiment. Students conduct initial weight and length measurements at HPL, and observe behavior, care for, and monitor the growth of three terrapins in their own classroom weekly.  At the conclusion of the project, students compare the growth rates of the three diets on the classroom terrapins to those at HPL. These final growth measurements occur in May at HPL.  Based on the data collected, the students determine which of the three diets resulted in optimal health and growth of the terrapins. In following the scientific method, based on their findings, students analyze their data and form conclusions. The terrapins are then released in coordination with MES personnel involved with restoration efforts at Poplar Island.

Results from Year 1 Pilot

Average Increases in Carapace Length

HPL
Gold: 94.8%; Silver: 85.1%; Bronze: 80.7%
Country School
Gold: 101.1%; Silver: 96.7%; Bronze: 63.8%
St. Michael's Middle School
Gold: 94.5%; Bronze: 80.8%
Bennett Middle School
Gold: 20.8%; Bronze: 28.9%

Links

Terrapin Institute and Research Consortium
http://www.terrapininstitute.org/

Chesapeake Terrapin Allianc
http://www.cterrapin.org

Arlington Echo
http://www.arlingtonecho.org/terrapinconnections

Poplar Island
http://www.nab.usace.army.mil/projects/Maryland/PoplarIsland/index.html

http://www.umces.edu/hpl/poplar-island-restoration-project

Maryland SeaGrant
http://www.mdsg.umd.edu/issues/chesapeake/other_species/terrapins/index.php

Book – Diamonds in the Marsh. 2006. Barbara Brennessel. University Press of New England. Lebanon, NH.

Gender Allocation and Growth Study
Investigators: Vic Kennedy¹, Willem Roosenberg² ,  Andrew Lazur¹,  and Erin Markin¹

¹ Horn Point Laboratory
² University of Ohio

Project objective: Adaptive significance of temperature-dependent sex determination (TSD)

In terrapins, and many other species of turtles, sex is determined by the temperature that the eggs incubate.  Because sex and temperature are linked it is difficult to tease apart the effects that are caused by temperature and those that are a consequence of gender.  In our study we used the hormones estradiol and letresol to create females at male producing temperatures (28^o C) and males at female(30.5^o C) producing temperatures. Thereby we have decoupled gender and temperature effects.  The objective of raising the animals is to determine if there are other phenotypic traits that may be influenced by temperature in addition to sex.  Some preliminary data suggests that females incubated at male producing temperatures grow at the same slower rate as males.

Why are we interested?
1) We can evaluate the academic question of the adaptive significance of TSD - a heretofore remaining unanswered

2) Hormonal manipulation has been suggested as a conservation tool to produce the rarer sex in hatcheries - this study critically evaluates using that technique.

3) There is the global warming issue and how climate change potentially could impact this species and turtles in general.

Terrapins were raised in our grow-out facilities with controlled temperature and photo-period. Each terrapin was measured and weighed every month to monitor growth.

After one year, the sex of each animal was determined and data is currently being analyzed to determine the effects of the hormones.