Metabolic Responses of Christmas Tree Worms (Serpulidae: Spirobranchus) to Thermal Acclimation.

Serpulids are an ecologically important group of sessile suspension feeders that play a key role in benthic-pelagic coupling by filtering and transforming suspended organic matter from the water column. Temperature is one of the main abiotic factors influencing marine ectotherm physiology and metabolic responses, including serpulids and their growth, survival and distribution patterns. Thus, the present study objective was to determine thermal acclimation effects on metabolic responses of two serpulid species-Spirobranchus spinosus and S. cf. corniculatus-distributed in the temperate Northern Pacific and tropical Eastern Pacific, respectively. Both adult tubeworm species were collected from the wild and acclimated for 30 days at different temperatures, directly affecting oxygen consumption (OCR) and ammonia excretion (AER) rates of both species. However, OCR decreased for warm-water species S. cf. corniculatus at 33°C. The O:N values of both species were low at all acclimation temperatures (0.5-3.9), indicating that individuals were using protein catabolism to obtain energy. The present study not only provides basic data on these two tubeworm species metabolic responses for the first time but also contributes to understanding how their metabolism is influenced by environmental changes (e.g., ocean warming), which may help assess their capacity to cope with climate change scenarios.