A new study has revealed that Caribbean spiny lobsters have developed behaviours to reduce disease transmission, through creating ‘safe havens’ where they can avoid infected individuals.
The study, co-authored by Associate Professor Don Behringer of the University of Florida, showed that the species uses a form of ‘behavioral immunity’ to prevent the spread of the PaV1 virus. PaV1 (Panulirus argus Virus 1) is a pathogenic virus that was discovered infecting juvenile Caribbean spiny lobsters in 2000. The virus is typically lethal within weeks or months for infected juvenile lobsters, but declines among larger juveniles and adults. The modes by which PaV1 can be transmitted include contact and ingestion. The disease is responsible for taking a heavy toll on lobster populations in the $50 million annual spiny lobster fishery in Florida.
“Increased infection risk has long been deemed a cost for the many benefits of being a social animal. However, we have shown that a social marine animal, the spiny lobster, has developed behaviors to reduce disease transmission by avoiding infected individuals,“
said Behringer, a UF/IFAS scientist in the School of Forest Resources and Conservation Program in Fisheries and Aquatic Science.
“Further, this behavioral immunity keeps potential epidemics of PaV1 from occurring.“
Sea sponges act as nursery habitats for juvenile spiny lobsters where they can shelter during their more vulnerable life stage. In 2007, a massive sponge die-off in a 926-square mile area of the Florida Keys occurred, with the resulting lack of shelter available leading to mass aggregations of juvenile lobsters in the remaining sheltered regions. Behringer and fellow scientists studied the data collected at the time regarding the prevelance of PaV1 in these aggregations over the years following the mass sponge die off .
Surprisingly, the scientists saw no increase in the prevalence of the virus in these areas that were dense with lobster individuals. Infectious diseases usually spread rapidly in populations of aggregated individuals, thus the absence of the virus lead to speculation that healthy lobster individuals must be somehow preventing themselves from contracting PaV1.
To investigate this hypotheses, the researchers introduced either a healthy or an infected lobster to other lobsters living naturally under sponges that had survived. Healthy lobsters left dens following introduction by lobsters infected with the PaV1 virus, despite the scarcity of other shelters and the high risk of being preyed upon while searching for a new shelter, and did not return to their den. In contrast, when a healthy lobster was introduced, the lobsters that were already there remained in the den, as their was no threat of disease.
The combination of field surveys after the sponge die-off, experiments and simulation modelling supports the hypothesis that spiny lobsters practice behavioural immunity and that it can suppress a likely marine epidemic, Behringer said.
“Understanding all we can about its impacts and the natural ways lobsters reduce infection risk is of great economic importance,” he said.
Header Photo Credit: NOAA, 2010 : A Caribbean spiny lobster on the sea floor. This photo was shot during a 2010 NOAA expedition in the U.S. Virgin Islands to map underwater habitats and the marine life they support.
- Mark J. Butler, Donald C. Behringer, Thomas W. Dolan, Jessica Moss, Jeffrey D. Shields. Behavioral Immunity Suppresses an Epizootic in Caribbean Spiny Lobsters. PLOS ONE, 2015; 10 (6): e0126374 DOI:10.1371/journal.pone.0126374