Turtles, turtles, and more turtles!

Nicole

Kate

    

      Why is Nicole smiling ... and why have I not posted in four days? We were successful beyond my expectations. Kate and I caught eight turtles, gathered dozens of samples, and took over two hundred photographs. Even two days later, today, I am still working a twelve-hour day finishing up cataloging and organizing what we collected, compiling data, and preparing the equipment for next weeks work.

      One of the most exciting discoveries is that western pond turtles living in this waterway are eating the nymphs of Odonates (dragonflies and damselflies) as well as crayfish. In addition, the preliminary results from the D-net bankside survey and the activity traps show that the ecosystem is more diverse than I anticipated. Last year, all the stomach content samples were crayfish but this year most of the turtles seem to have numerous insect body parts, Odonata nymphs in addition to crayfish.

As seen here, each turtle gets its own container throughout the process. The paper hanging in each container is a record of its vital statistics and a record of its response to anesthesia and gastric lavage.

     One of the real treats was finding Odonata exuvia in the bull rushes. When the nymphs of Odonates reach the point when they are ready to emerge as an adult they crawl up onto a leaf and attach themselves. Then after many hours, the mature, soft-bodied adult splits the exoskeleton, emerges, and slowly hardens into the final adult. Exuvia, the fragile remains of the process, were scattered throughout the area. I photographed some and then we collected them for identification. Because of the intense amount of Odonata mating activity going on around us as well worked, we are likely to see many more nymphs in turtle stomachs in the future.

An old exuvia being used by a spider.

The exuvia is the exoskeleton of a Odonate nymph that has crawled out on a leaf and then emerged as an adult. These along with the presence of mating pairs of dragonflies and damselflies is a good sign this ecosystem can support a fairly long lived organism. The different stages, called instals, take several years to mature.

Another more recent exuvia. The white threads are the tracheal linings.

As a nymph the Odonate uses gills to obtain oxygen from the water. As an adult they have holes in the abdomen called spiracles; these tubes allow air to pass into the body for oxygen exchange. While the emerging adult is making the transition to a fully functioning adult the tracheal linings are broken as the body hardens.

A close-up of an exuvia showing the tracheal lining and the opening in the exoskeleton where the adult emerges.