Bleeding Endangers Horseshoe Crabs

It has been an established practice to collect and bleed horseshoe crabs for biomedical science research and biomedical engineering purposes. The animal’s blue blood is being harvested for pharmaceutical use. A product synthesized from their blood called Limulus amebocyte lysate (LAL), is an important component in the preservation of vaccines and medical equipment, making sure that they are free from any microorganism contamination. Only the blue blood of horseshoe crabs can be used to produce this important compound.

About half a million of horseshoe crabs are being collected and bled each year. During the process, about 30 percent of their blood volume was lost, and approximately 20 to 30 percent of the horseshoe crabs do not survive the bleeding, according to Chris Chabot, professor of neurobiology at PSU.

In the journal The Biological Bulletin, Chabot and his colleagues have published their study entitled “Sublethal Behavioral and Physiological Effects of the Biomedical Bleeding Process on the American Horseshoe Crab.” In the said research, Chabot, together with Win Watson, UNH professor of zoology, and Rebecca Anderson, a PSU graduate student, collected horseshoe crabs and harvested their blood practically replicating the bleeding process for the production of LAL. After which, the crabs were observed for any changes in behavior and movement.

Two weeks after the bleeding, the team observed that the crabs moved less frequently with different movement patterns compared to their previously recorded timing and rhythms of movement. This, the researchers said, may be a sign of disorientation.

Anderson points out that one of the potential problems this finding might incur is that the harvest usually occurs during the crabs’ breeding season since it is easier to collect them at these times. After the bleeding process, the physiological changes that the crabs experience might prevent them from breeding thus having a large impact on the population of the horseshoe crabs.

Chabot suggests that the pharmaceutical industries might consider collecting and harvesting after the breeding season. Furthermore, he points out that considerations should be considered to ensure that biomedical bleeding is a sustainable practice and does not disrupt the coastal ecosystem.

The researchers hope that through this study, management regulations would be redesigned to take the needs of the crabs and the people into consideration.

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