KOZLOWSKI, Lauren B; BOWDEN, Rachel M; Illinois State Univ; Illinois State Univ: Improved yolk removal techniques elevate hatching success in the Painted Turtle

Studies utilizing yolk removal techniques have been highly successful in birds and lizards, with the majority of manipulated eggs surviving to hatch. In sharp contrast, studies employing yolk removal techniques in turtles have been plagued by low hatching success (12-45%) which has been attributed to embryonic trauma, fungal infections, or contamination. Yolk removal permits the assessment of early yolk components (especially those that may be of maternal origin) for comparison with later yolk or hatchling variables. Our goal was to improve hatching success by modifying yolk removal and egg maintenance techniques in turtle eggs. We collected five clutches of painted turtle (Chrysemys picta) eggs during June 2004. All clutches were brought into the lab within 48 hours of oviposition. Each egg was thoroughly cleaned of any dirt or debris before being swabbed with a Betadine solution at the site of needle insertion. A new, sterile infusion set was used to remove ~10 mg of yolk, and the puncture site was then sealed with tissue glue. If the glue applicator came into contact with the egg, the tip was trimmed or it was disposed of prior to the next application. Boxes of sterile vermiculite were prepared and kept sealed to prevent contamination. The vermiculite was moistened (-150 kPa) and eggs were placed into the boxes just prior to being placed into 28 °C incubators. Eggs were checked at least twice weekly to assess embryonic survival. Any egg that appeared discolored or shrunken was removed immediately and the remaining eggs were relocated to a new incubation box. This methodology resulted in 66% hatching success. Improved yolk removal technique and subsequent care in incubation conditions elevated hatching success, making egg manipulation studies in turtles feasible.