Figure 1.

(a) Field survey of ranavirus occurrence and associated die-offs. (a) Map indicating locations of the 18 ephemeral ponds monitored weekly in June and July for ranavirus-associated die-offs of wood frog larvae in the vicinity of Yale Myers Forest in Northeastern CT, USA (top-left subset), a 32 km² managed mixed-hardwood forest. Numbered sites on map refer to the ponds from which larvae were collected to observe the progression of naturally acquired ranavirus infections (11 ponds, d,e). Die-offs of greater than 90% were observed in seven ponds while die-offs were not observed in the remaining eleven ponds. (b) Proximity to major roads was correlated with the probability of observed die-offs. (c) Log₁₀ ranavirus eDNA concentration by conductivity (measure of salinity) during early larval development. (mean ± s.e.m.) (d) Average days to death of naturally infected animals in captivity after collection with a line of predicted survival from Cox proportional hazards analysis. (e) Average larval ranavirus (RV) titre of infected animals collected in the field and monitored for mortality in the laboratory by pond salinity (11 sites numbered in a; n = 96; 3–11 per site). Lines and shaded areas are the logistic (b) or linear (c,e) regression lines and the 95% confidence envelope. In (a–e), black and grey points indicate ponds where die-offs were and were not observed, respectively. (Online version in colour.)