Microbial dysbiosis precedes signs of sea star wasting disease in wild populations of Pycnopodia helianthoides

Sea star wasting (SSW) disease, a massive and ongoing epidemic with unknown cause(s), has led to the rapid death decimation of sea populations cascading ecological consequences. Changes in microbial community structure have been previously associated SSW, however, it remains if SSW-associated dysbiosis is mechanism or artifact disease progression, particularly wild populations. Here, we compare microbiomes sunflower star, Pycnopodia helianthoides , before (Naïve) during (Exposed Wasting) initial outbreak Southeast Alaska identify changes interactions communities health exposure. We found an increase diversity (both alpha beta diversity) preceding signs abundance facultative obligate anaerobes (most notably Vibrio ) both Exposed (apparently healthy) Wasting animals. Complementing these composition was gain metabolic functions upon exposure, loss function wasting. Using Bayesian network clustering, evidence form co-colonization taxa appearing large numbers among individuals, addition Naïve stars. These suggest shared set colonizing microbes that may be important stages SSW. Together, results provide several complementary perspectives support early dysbiotic event visible