Lesions, pits in the shell, and even death can be the result for an American lobster afflicted with shell disease. There have been a number of studies dedicated to finding out what epizootic shell disease—the variation of the disease that affects wild populations and has severely impacted the southern New England lobster fishery. Scientists now know that shell disease is caused by an onslaught of bacteria in the environment, but there hasn’t been any research on treating the disease—until now.

“Prior research has focused on the cause of the disease, but no one has really looked at treatment,” said Anita Kim, Assistant Scientist at the Anderson Cabot Center for Ocean Life.

Kim is the lead author on a recently published paper testing treatments for laboratory-based shell disease on juvenile American lobsters. The paper was published in the July 2018 issue of the Bulletin of Marine Science.

Kim and her team performed two different experiments for treating laboratory-based shell disease on juvenile American lobsters. The researchers performed two unique experiments to test the effectiveness of short-term treatment methods of shell disease in laboratory-raised lobsters.

Scientist in the Lobster Lab.
Anita Kim in the Lobster Lab.
Claw puncture wounds on lobsters with laboratory-based shell disease.
Claw puncture wounds on lobsters with laboratory-based shell disease.

Anderson Cabot Center Associate Scientist interacts with a juvenile American lobster (left). Claw puncture wounds on lobsters with laboratory-based shell disease (right). 

The first experiment tested the effects of using a commercially available product designed to treat fish lesions on early- and late-stage shell disease. The product, Hikari Biobandage, was not effective at limiting shell disease in nonfacilitated regions (areas that got the disease naturally) or in facilitated regions (where the shell was damaged to induce the disease).

The team’s second experiment examined the resulting shell disease when lobsters were treated with various agents: fresh water, a povidone-iodine solution, Vitamin E oil, formalin, and malachite green. The researchers found that fresh water actually exacerbated the facilitated disease compared to animals treated with the povidone-iodine solution, formalin, or malachite green. Lobsters treated with malachite green or formalin had the slowest rate of lesion development. The researchers observed a higher amount of nonfacilitated shell disease on their control group lobsters, which may simply be due to frequent handling by the scientists.

Of the six treatments the research group tested, only malachite green and formalin were effective at both limiting the formation of lesions and limiting the expansion of the shell disease. Kim stressed that these are chemicals that can only be used in controlled environments and recommended investigating alternative treatments.

An American lobster with shell disease.
An American lobster with shell disease.

Although epizootic shell disease presents differently than laboratory-based shell disease, Kim said she hopes this research could be a unique way to understand the disease in wild populations.

“It’s a bit of backwards thinking, but if you can find the solution to the problem, it can help you understand the problem itself,” said Kim. “Identifying treatments to shell disease, both treatments that work and those that don’t, might give us new information about the disease.”

Kim, A., Seid, C., Mcelhiney, A., & Tlusty, M. (2018). Treatment of a laboratory-based model of shell disease in hatchery raised American lobsters (Homarus americanus). Bulletin of Marine Science, 94(3), 923-943. doi:10.5343/bms.2017.1106