Growth and longevity of the tubeworm Ridgeia piscesae in the variable diffuse flow habitats of the Juan de Fuca Ridge

The hydrothermal vent tubeworm Ridgeia piscesae visually dominates the vent environments in the northeast Pacific. One common vent habitat where R. piscesae flourishes is among diffuse vent flow on basaltic substrata. We used chemical analysis of discrete water samples combined with long-term temperature monitoring in 7 aggregations to characterize the immediate habitat of the 'long-skinny' morphotype of R. piscesae. We also monitored in situ growth of 536 individuals from 8 separate aggregations. The temperature data show that exposure of most individuals to vent fluid at the plume level is extremely low compared to other previously studied hydrothermal vent tubeworms, which indicates significant microhabitat heterogeneity at small spatial and temporal scales. The growth rates of this morphotype of R. piscesae ranged from 0 to 252 mm yr super(-1) and were highly variable between individuals in the same aggregation and between different vent sites. However, individual growth rates in consecutive years show no significant difference and are correlated, indicating long-term stability of the sulfide source in some of these aggregations. This study found no significant relationship between initial tubeworm size and corresponding growth rates. The median plume-level temperature in an aggregation was not significantly correlated with growth rate over the entire dataset. In addition, very conservative longevity estimates suggest that this morphotype of R. piscesae lives for decades in the hydrothermal vent environments of the Juan de Fuca Ridge.