Thermal tolerance during early ontogeny in the common whelk Buccinum undatum (Linnaeus 1785): Bioenergetics, nurse egg partitioning and developmental success
Journal of Sea Research
Elsevier / NIOZ Royal Netherlands Institute for Sea Research
Temperature is arguably the primary factor affecting development in ectotherms and, as a result, may be the driving force behind setting species' geographic limits. The shallow-water gastropod Buccinum undatum is distributed widely throughout the North Atlantic, with an overall annual thermal range of below zero to above 22 °C. In UK waters this species is a winter spawner. Egg masses are laid and develop when sea temperatures are at their coolest (4 to 10 °C) indicating future climate warming may have the potential to cause range shifts in this species. In order to examine the potential impacts of ocean warming, we investigate the effects of temperature on the early ontogeny of B. undatum across a thermal range of 0 to 22 °C. Each egg mass consists of approximately 100 capsules, in which embryos undergo direct development. Successful development was observed at temperatures ranging from 6 to 18 °C. Rates of development increased with temperature, but the proportion of each egg mass developing successfully decreased at the same time. With increasing temperature, the mean early veliger weight increased, but the number of early veligers developing per capsule decreased, suggesting a negative impact on the number of crawl-away juveniles produced per capsule. Elemental analysis showed both carbon (C) and nitrogen (N) to increase with temperature in early veligers but not in hatching juveniles, indicating greater energy reserves are accumulated during early ontogeny to compensate for the higher energetic demands of development at higher temperature. The developmental plasticity observed in B. undatum suggests this species to be capable of adapting to temperatures above those it currently experiences in nature. B. undatum may possess a thermal resilience to ocean warming at its current upper temperature distribution limit. This thermal resilience, however, may come at the cost of a reduced offspring number.
Thanks are given to the skipper and crew of RV Callista (University of Southampton) for their help with sample collection. Thanks are also given to Shir Akbari (University of Southampton) for his help with elemental analysis, and to Adam Reed, Alastair Brown, and Andrew Oliphant for help with animal maintenance. This work was supported by grants from the Total Foundation (Abyss2100) to S.T. and the Malacological Society to K.S.
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.
Vol. 79, pp. 32 - 39