Data from: El Niño drives a widespread ulcerative skin disease outbreak in Galapagos marine fishes

Climate change increases local climatic variation and unpredictability,
which can alter ecological interactions and trigger wildlife disease
outbreaks. Here we describe an unprecedented multi-species outbreak of
wild fish disease driven by a climate perturbation. The 2015–16 El Niño
generated a +2.5 °C sea surface temperature anomaly in the Galapagos
Islands lasting six months. This coincided with a novel ulcerative skin
disease affecting 18 teleost species from 13 different families. Disease
signs included scale loss and hemorrhagic ulcerated patches of skin, fin
deterioration, lethargy, and erratic behavior. A bacterial culture
isolated from skin lesions of two of the affected fish species was
identified by sequencing of the 16S rRNA gene as a Rahnella spp. Disease
prevalence rates were linearly correlated with density in three fish
species. In January 2016, disease prevalence reached 51.1% in the
ring-tailed damselfish Stegastes beebei (n = 570) and 18.7% in the king
angelfish Holacanthus passer (n = 318), corresponding to 78% and 86%
decreases in their populations relative to a 4.5-year baseline,
respectively. We hypothesize that this outbreak was precipitated by the
persistent warm temperatures and lack of planktonic productivity that
characterize extreme El Niño events, which are predicted to increase in
frequency with global warming.