Handling a yellow stingray prior to blood sampling. Thursday, February 13th, researchers from the Shark Research and Conservation Program completed the second round of sampling for the program’s stingray physiology project. The project aims to understand how the immune response of yellow stingrays (Urobatis jamaicensis) changes as a result of long-term exposure to a chronic stressor. After Thursday’s sampling, stingrays will be exposed to increased levels of dissolved carbon dioxide for two weeks at levels forecasted from climate change models. This project has implications for better understanding the long-term responses of sharks to a chronic stressor since stingrays are closely related to sharks, and it is more practical to keep stingrays in a lab for long durations.

A typical sampling event involves drawing blood from all 20 stingrays. Blood is drawn from the caudal vein running along the bottom of the tail. The vein is encased in a cartilage sheath and is so small that needles used are 0.016 inches, or 0.4 millimeters, wide. Blood is prepared in a neutral buffered formalin solution and smeared on slides in preparation for tests to determine the total white blood cell count and proportions in which different white blood cells occur together. Sampling will occur three more times until the end of the month, at which point all current animals will be released, and 20 more will be caught for a second replicate.

The research team is particularly excited because this is only the third study to observe changes in immune function in sharks and rays, and this is the first study to observe changes in the immune response over a long duration. This project is a collaborative effort between researchers at the New England Aquarium, Carleton University, the Baltimore Aquarium, and the University of Illinois.