Many Questions Remain Unanswered About the Role of Microbial Transmission in Epizootic Shell Disease in American Lobsters (Homarus americanus)

Abstract

Despite decades of research on lobster species’ biology, ecology, and microbiology, there are still unresolved questions about the microbial communities which associate in or on lobsters under healthy or diseased states, microbial acquisition, as well as microbial transmission between lobsters and between lobsters and their environment. There is an untapped opportunity for metagenomics, metatranscriptomics, and metabolomics to be added to the existing wealth of knowledge to more precisely track disease transmission, etiology, and host-microbe dynamics. Moreover, we need to gain this knowledge of wild lobster microbiomes before climate change alters environmental and host-microbial communities more than it likely already has, throwing a socioeconomically critical industry into disarray. As with so many animal species, the effects of climate change often manifest as changes in movement, and in this perspective piece, we consider the movement of the American lobster (Homarus americanus), Atlantic Ocean currents, and the microorganisms associated with either.

Warmer water temperature and epizootic shell disease reduces diversity but increases cultivability of bacteria on the shells of American Lobster (Homarus americanus)

“…During the course of our study, 61% of the healthy lobsters and 59% of the diseased lobsters molted, and lobsters may recover from ESD if they survive molting (Stevens, 2009). Temperature, food availability, and reproductive status can impact the timing of molt, which can alter lobsters’ susceptibility to bacteria or the environment, as discussed previously (Ishaq et al, 2022). In this study, the diseased lobsters that molted and re-developed signs of shell disease were in the mid and high range temperature groups.…”

“…For example, tropical marine water lost bacterial diversity over time when stored in a ballast tank (Ng et al, 2015), and aquacultured tank systems typically have lower microbial diversity than seawater because microorganisms are filtered or killed to prevent disease and parasite load in animals. Marine animals acquire many of their associating microorganisms from their environments (Boscaro et al, 2022; Ishaq et al, 2022; Sousa et al, 2021), and even with a diverse shell microbiota at baseline it was expected that all lobsters would lose some bacterial diversity over time without a complex environment from which to replenish microorganisms.…”

“…Lobster population declines in SNE regions have also been attributed to ocean acidification through carbon dioxide deposition (Niemisto et al, 2021), pollution and anthropogenic disturbance (Goodman et al, 2021), and disease emergence (Harrington et al, 2020; Shields et al, 2012). Since then, population declines have been noted in progressively-more-northern fisheries, and there is concern that warmer ocean temperatures which are already pushing lobsters further north to cooler waters (Greenhalgh, 2016) may also push infectious disease to new locations (Ishaq et al, 2022; Reardon et al, 2018; Shields, 2019; Watson, 2005). In particular, the Gulf of Maine is warming faster than predicted (Poppick, 2018), and there is a concern that lobster fisheries could collapse in the way that other species, such as Atlantic cod ( Gadus morhua ), already have (Pershing et al, 2015).…”

“…ESD is recognized as a significant disease syndrome and is described as having a multifactorial and complex etiology with increased temperatures implicated as a contributing factor (Castro et al, 2012; Shields et al, 2012). The histological characteristics of the disease suggested a bacterial etiology but a causative agent has yet to be determined (Ishaq et al, 2022). Culture-dependent and culture-independent bacterial investigations have been performed on shell-diseased lobsters and shown that the etiology of the disease is complex, likely involving multiple bacterial species in the Alteromonadaceae, Flavobacteriaceae, Pseudomonadaceae, Rhodobacteraceae and Vibrionaceae families (Bell et al, 2012; Chistoserdov et al, 2012, 2005; Meres et al, 2012).…”

“…ESD is recognized as a significant disease syndrome and is described as having a multifactorial and complex etiology with increased temperatures implicated as a contributing factor (Castro et al, 2012;Shields et al, 2012). The histological characteristics of the disease suggested a bacterial etiology but a causative agent has yet to be determined (Ishaq et al, 2022).…”