Shell disease in crustaceans – just chitin recycling gone wrong?

Abstract

SummaryThe exoskeletons of aquatic crustaceans and other arthropods contain chitin, a biopolymer of b-(1,4)-linked N-acetylglucosamine together with associated proteins. Despite the vast amounts of chitin within such animals little is found in sediments and open water because microorganisms rapidly degrade this following its loss after moulting or upon the animals' death. Shell disease syndrome is a worldwide disease condition that affects a wide range of crustaceans. It comes about as a result of bacterial degradation of the exoskeleton leading to unsightly lesions and even death if the underlying tissues become infected. There are at least two potential forms of the disease; one that appears to centre around chitin degradation and an additional form termed 'epizootic' shell disease, in which chitin degradation is of less significance. This account reviews our current understanding of the causative agents of this syndrome, assesses the potential economic consequences of the disease, and critically examines whether it is associated with anthropogenic disturbances including pollution. Overall, despite extensive studies during the last few decades, the potential links between faecal, heavy metal and insecticide pollution and shell disease are still unclear.

The microbiome of North Sea copepods

“…2), 5 phylotypes were related to the Bacillales, a single phylotype fell into the Clostridiales. Both groups contain members capable of degrading chitin (Gooday 1990;Vogan et al 2008). Interestingly, related Bacillus spp.…”

Lesion bacterial communities in American lobsters with diet-induced shell disease

“…Bacterial infestation of compromised lobsters has been suggested as the cause of lobster shell disease (Tlusty et al 2007, Vogan et al 2008). Evidence for this was shown by Tlusty et al (2008) where lobsters fed exclusively on herring invariably became moribund and developed shell lesions (Tlusty et al 2008).…”

Increased Disease Calls for a Cost-Benefits Review of Marine Reserves

“…Claws are the lobsters’ principle weapon for defence, so will sustain much damage. Exoskeletal damage, especially to the waxy outer epicuticle, will allow entry to potential causative agents of shell disease, such as chitinoclastic bacteria and fungi, to the underlying procuticle, thus inducing exoskeletal infection and lesions [33]. High lobster abundance in the NTZ suggests that SD pathogens will be more prevalent in the local environment; and the common association of lobster SD with high host density [34]–[35] supports this theory.…”