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PROJECT OCEANOGRAPHY COASTAL REPTILES 139

COASTAL REPTILES

Lesson 2. Coastal Reptiles: TheDiamondback Terrapin

Lesson Objectives: This section focuses on the Diamondback Terrapin.

The student will become familiar with its physiology, habitat, andnesting behaviors.

Diamondback terrapins live incoastal salt marshesandestuaries along the Atlanticcoast from Cape Cod,

Massachusetts southward tothe Florida Keys thennorthward along the Gulf coastand west to Texas.Diamondback terrapins have awide tolerance of salt in theirwater, and are the only NorthAmerican turtles native tobrackish(salty, but not as saltyas the ocean) waters. Terrapins

may hibernate in their northerlyranges but do not seem tohibernate in their warmersoutherly ranges.

They are small to medium sizedturtles, and the females arelarger than the males. Their

carapace, the

top of their shell,is oblong-shaped, andrange in colorfrom gray to lightbrown to black.

Each of the seven sub-species

of diamondback terrapins hasslightly different markings, withgrooves and different-coloredconcentric markings on thescutes. For instance, there is aFlorida form of thediamondback terrapin which isslate black in color with a

widened head and jaw, which isused for eating barnacles offthe roots of mangrove trees.Diamondback terrapins maychange in appearance as theyget older.

When its time to lay their eggs,females leave the water to find

land in which they bury theireggs. They prefer sand, but canbe very resourceful when theyhave to find a suitable site,resorting to people's yards orroadsides when necessary.They dig a hole using their hind


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legs only, alternating each legto dig. They then layapproximately five to seveneggs in the hole, and cover it

up leaving no evidence thatthey have been there. Theythen make their way back to thewater.

Conservation of the Diamondback Terrapins

A major problem facing thediamondback terrapin is thatthe coastal areas where theyare found are becoming sodeveloped, it is getting harder

for the female to find sites to layher eggs. Prime laying areasare being paved over, forcingfemale terrapins to cross busycoastal roads to find a nestingsite. Often, they are hit by carsbefore they can lay their eggs.

A study was conducted on thenorthern diamondback terrapin

by scientists from the WetlandsInstitute, Stone Harbor, NJ andfrom Stockton College inPomona, NJ. They found thatfrom 1989-95, 4020 terrapinswere killed during the nestingseasons (early June throughmid-July) on the Cape May (NJ)Peninsula alone. They were

able to harvest3690 eggsfrom terrapins that they foundkilled in the road, and of thoseeggs, 1175 producedhatchlings.

The Wetlands Institute at StoneHarbor, New Jersey, is givingterrapins a head start. In thisprogram, researchers retrieveeggs from female terrapins

killed by road traffic. Theresearchers incubateandhatch the eggs, and raise thehatchlings until they are 2-3years old. The young terrapinsare then released back into thewild. They are much larger andstronger and, hopefully, have abetter chance of surviving thannew hatchlings.

Researchers at the WetlandsInstitute have incubateddiamondback terrapin eggs atvarious temperatures. Theyhave found that at 26C(78.8F) the hatchlings arepredominately male. At 32C(89.6F) the hatchlings are all

females. Scientists refer to thisas temperature dependentsex determination.


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COASTAL REPTILES

Wetlands Institute Findings1989 1990 1991 1992 1993 1994 1995 Total

Total # ofRoad Kills 273 1077 712 586 535 419 418 4020

Total # ofeggs

salvaged180 933 746 734 448 399 250 3690

# ofResultantHatchlings

77 85 286 235 222 157 113 1175

HatchlingSuccess

43% 9% 38% 32% 50% 39% 45% 32%

The scientists have concludedby the declining number ofkilled terrapins found on theroadside, that the terrapinpopulation is reducing. Theyfactor in the fact that vehicular

traffic has increased, that thereare no barriers established tokeep the terrapins fromcrossing the roads. Scientistsalso consider the fact that theyhave more students on"terrapin patrol" looking foreither live terrapins crossing theroad (which the students help)or killed terrapins.

Scientists have created indoorfarms to raise the hatchlings so

they can safely grow.Protecting the hatchlings givesthem a better chance ofsurvival than they would havein the wild. Once they get to acertain length, 5 to 7 cm, they

are large enough to bereleased. When they attain thatsize, it is difficult for mostmarsh predatorsto swallowthem whole, giving the terrapina better chance of reachingadulthood. Unfortunately, evenif all the hatchlings were toreach adulthood, which doesnot occur, they still do notnumber enough to replace thepopulation of females killed inthe road.


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COASTAL REPTILES

Crab Traps

In cooperation with the Bureau

of Marine Fisheries, Dr. RogerWood of the Wetlands Institutewas contracted to continueevaluating a simple device

designed toreduce by-catchofdiamondbackterrapins in

commercialcrab traps.Biologistssuspect that

one of the primary sources ofmortality for diamondbackterrapins is incidental drowningin commercial crab traps. It isestimated that five terrapins dieeach day per 100 crab traps;

along New Jersey's coastalone, an estimated 30,000-40,000 terrapins die each yearin traps. One out of threeterrapins caught in a crab trapdies. By developing aninexpensive way to reducedrowning in crab traps, and one

which

does notunfairlyburden

commercial crab trappers,biologists hope to preclude thenecessity of federal listing andbegin restoring diamondbackterrapin populations.

Researchers have developed adevice, called a BycatchReduction Apparatus(BRA),that has reduced terrapindrowning by 70-90%. It issimply a 5" X 7" wire opening inthe upper part of the trap that islarge enough for most of thetrapped terrapins to escape.Although some of the smaller

crabs may also escape throughthe BRA, the marketable crabsare left in the trap for thecrabber.

Often traps are left for yearswithout being recognized as anabandoned trap.


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COASTAL REPTILES

Percentage of trapsset where terrapins

occur

Number of drownedterrapin in 4 month

season

Number of drownedterrapin in 5 month

season50% 71,340 88,74025% 35,670 44,37010% 14,268 17,748

Source: The Wetlands Institute, NJ

Threats

Other potential threats to thediamondback terrapin includedevelopment of coastal regions,the terrapin's nesting grounds;incidental kills by motor boats;road mortality of nestingfemales, predation on adults byraccoons and pet trade byhumans.

For the past five years,scientists have recommendedplacing the diamondbackterrapin on the federalendangered species list. Theirnumbers dwindled at the turn ofthe century, mostly due to thefact that the terrapins were a

delicacy and were served at thefanciest of dinners. Althoughthey were never federallyprotected, some states, suchas Massachusetts, have fullyprotected the diamondback,while others, such as NewJersey, allow a legal huntingseason with no capture limit.Studies show that thediamondback terrapinpopulation is declining inseveral states: Louisiana,Mississippi, Florida, SouthCarolina, Maryland and NewJersey and remaining stable oreven increasing in its otherlocales.


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How you can help:

Do not buy terrapins in a pet store. This is a great way to end

up with a sick animal, which will only be a hassle to you. Let'send the demand for pet store turtles by not buying them.

1. Support turtle conservation and land acquisitions organizations.

2. Educate others about the plight of this species.

3. Create public awareness on roadways near terrapin nesting areas.

4. Support state regulations that will help reduce terrapin mortality incrab traps.

5. Support state regulations restricting the commercial trade inDiamondback terrapins

LISTING STATUS

The following definitions apply to listings for FCREPA, FGFWFC, and USFWS.ENDANGERED: Species in danger of extinction if the deleterious factorsaffecting their populations continue to operate.

THREATENED: Species that are likely to become endangered in the foreseeablefuture if current trends continue.

RARE: Species that, although not presently endangered or threatened asdefined above, are potentially at risk because they are found only within arestricted geographic area or habitat.

SPECIES OF SPECIAL CONCERN (SSC): Species that do not clearly fit into

one of the preceding categories yet warrant special attention.


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LISTING AGENCIES

CITES:Convention of International Trade of Endangered Species

FCREPA: Florida Committee for Rare and Endangered Plants and Animals

FGFWFC: Florida Game and Fresh Water Fish Commission

FNAI: Florida Natural Areas Inventory

USFWS: U.S. Fish and Wildlife Service

Picture credits:http://www.best5.net/animal/APAsrch3.cgi?dspNum=5&qt=terrapin


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PROJECT OCEANOGRAPHY STUDENT INFORMATION SHEET 2 146

REFERENCES

References

Boykin, Scott. Independent biologist. Gulfport, Florida.

Heinrich, George L. Boyd Hill Nature Park, St. Petersburg Florida.

Wood, Roger C. and R. Herlands.Terrapins, tires and traps:conservation of the northern diamondback terrapin (Malaclemysterrapin terrapin) on the Cape May Peninsula, New Jersey, USA.The Wetlands Institute: Stone Harbour, NJ. 1996.State of New Jersey Department of Environmental Protection

Great Web sites:

http://www.tortoise.org/archives/malaclem.htmlhttp://www.uga.edu/~srel/terrapin.htmhttp://www.state.nj.us/dep/fgw/diaback.htm


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Student Information Sheet 2. CoastalReptiles II: Diamondback Terrapin

Diamondback terrapins live incoastal salt marshesandestuaries along the Atlanticcoast from Cape Cod,Massachusetts southward tothe Florida Keys thennorthward along the Gulf coastto Texas. Diamondbackterrapins have a wide tolerance

of salt in their water, and arethe only North American turtlesnative to brackish(salty, but

not as salty as the ocean)waters. Terrapins mayhibernate in their northerlyranges but do not seem to

hibernate in their warmersoutherly ranges.

Conservation of Diamondback Terrapins

A major problem facing thediamondback terrapin is that

the coastal areas where theyare found are becoming so

developed, it isgetting harder forthe female to findsites to lay hereggs. Primelaying areas arebeing paved

over, forcing female terrapins tocross busy coastal roads to finda nesting site. Often, they arehit by cars before they can laytheir eggs.

The Wetlands Institute at StoneHarbor, New Jersey, is giving

terrapins a head start. In thisprogram, researchers retrieveeggs from female terrapinskilled by road traffic. Theresearchers incubateandhatch the eggs, and raise thehatchlings until they are 2-3years old. The young terrapinsare then released back into thewild. They are much larger andstronger and, hopefully, have abetter chance of surviving thannew hatchlings.


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COASTAL REPTILES

Crab Traps

In cooperation with the Bureau

of Marine Fisheries, the ENSPagain contracted with Dr. RogerWood of the Wetlands Instituteto continue evaluating a simple

devicedesigned toreduce by-catchofdiamondback

terrapins incommercialcrab traps.Biologists

suspect that one of the primarysources of mortality fordiamondback terrapins isincidental drowning incommercial crab traps. It isestimated that five terrapins die

each day

per 100crab traps;along NewJersey'scoast alone, an estimated30,000-40,000 terrapins dieeach year in traps. One out ofthree terrapins caught in a crabtrap dies. By developing an

inexpensive way to reducedrowning in crab traps, and onewhich does not unfairly burdencommercial crab trappers,biologists hope to preclude thenecessity of federal listing andbegin restoring diamondbackterrapin populations.

How you can help:

Do not buy terrapins in a pet store. This is a great way to endup with a sick animal, which will only be a hassle to you. Let's

end the demand for pet store turtles by not buying them.


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Activity 2-1. Classroom DiscussionQuestions

1. What would be the benefits of having a crab season? Crab seasonwould reduce the number of unused, abandoned crab traps, thusreducing the number of terrapins caught in these traps.

2. What would be the disadvantages? Crabbers would lose money.

3. Do you think there is a way reduced the number of terrapins killedby vehicles? If you were able to create a device that would alertthe turtles to vehicles what would it look like? How would it work?

4. What are other potential threats to Terrapins? Other potentialthreats to the diamondback terrapin include development ofcoastal regions, the terrapin's nesting grounds; incidental kills bymotor boats; road mortality of nesting females and predation onadults by raccoons.

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