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From Tracking Horseshoe Crabs by Acoustic Telemetry on the Stony Brook Newsroom on January 9, 2019.

Horseshoe crabs have been on earth since before dinosaurs, and they are an important part of the life ecosystem, as multiple marine animals, such as migratory shorebirds and Loggerhead sea turtles, critically depend on horseshoe crabs for food. Horseshoe crabs have also played an integral role in human health advancements, as compounds in their blood can detect bacterial pathogens, and thus, has helped reduce the risk of infection associated with human medical supplies in recent decades. Therefore, being able to track the underwater seasonal movements of Atlantic horseshoe crabs would provide insight into their habitat use and help facilitate horseshoe crab management strategies. Justin Bopp, a SoMAS Ph.D. student working with Dr. Robert Cerrato, is using a method of acoustic telemetry to track horseshoe crab movements.

The primary technique that Justin uses to track the underwater movements of horseshoe crabs is acoustic telemetry, a method that uses the power of sound to help identify the location of marine animals throughout space and time. There are two essential technologies required when conducting an acoustic telemetry study: a passive acoustic receiver and several acoustic transmitters. First, acoustic receivers are placed in fixed locations underneath the water’s surface and be deployed for months at a time. Then, acoustic transmitters (the black cylindrical device in the included photo) are attached to the shell surface of each individual horseshoe crab and each acoustic transmitter emits a series of acoustic “pings” at a uniform frequency every one to two minutes that is unique to each individual crab.

As horseshoe crabs tagged with acoustic transmitters move underwater and are within the detection range of a submerged receiver (100-300 meters), the receiver logs the detection date and time of each individual crab. In addition, Justin can ascertain which general location each horseshoe crab was detected since he knows the exact location of each acoustic receiver. Acoustic telemetry also provides researchers with a rich amount of animal movement data; over the past two years, he has tracked the movements of over 80 horseshoe crabs in the New York region using this technique.

Findings from Justin’s research will hopefully provide novel insight into the habitat connectivity of local horseshoe crab populations and will have the potential to facilitate horseshoe crab management strategies.

The research is funded in part by the New York State Department of Environmental Conservation through the Ocean and Great Lakes award.


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