Size metrics, longevity, and growth rates in Umbellula encrinus (Cnidaria: Pennatulacea) from the eastern Canadian Arctic.

• Published in: Arctic Science
• Main Authors: Bárbara de Moura Neves, Evan Edinger, Vonda Wareham Hayes, Brynn Devine, Laura Wheeland, Graham Layne
• Format: Article in Journal/Newspaper
• Language: English; French
• Published: Canadian Science Publishing 2018
• Subjects: deep-water corals; size distribution; growth rings; radiocarbon analysis; trace element analysis; Environmental sciences; GE1-350; Environmental engineering; TA170-171; Arctic; Baffin Bay; Canada; Greenland; Dyer; Jones Sound; Cape Dyer; Baffin
• Online Access: https://doi.org/10.1139/as-2018-0009; https://doaj.org/article/bc1313d303a34f2ca3fdf1f16870fb26

Umbellula encrinus (Linnaeus, 1758) is a deep-water sea pen commonly found in the eastern Canadian Arctic. It can reach heights of >2 m, and it has often been caught as fishing bycatch. Here, we characterized abundance/density, size metrics, longevity, and growth rates of U. encrinus colonies from Baffin Bay (between Greenland and Canada). No prevalent size classes were identified at most locations, except for Jones Sound and Cape Dyer, where small-size colonies dominated. Average number of growth rings in the internal skeleton (axis) of the examined colonies ranged between 2 and 68, with a maximum of 75. A bomb-14C analysis yielded 14C curves comparable with those of other deep-water octocorals with annual ring formation. A trace element analysis of Mg/Ca, Sr/Ca, Ba/Ca, and Na/Ca yielded values oscillating along the axis radius, with the number of peaks and growth rings being comparable. Growth rates averaged 0.067 ± 0.015 mm year−1 (radial extension) and 4.5 ± 1.2 cm year−1 (linear extension), considering rings to be formed annually. Relationships between radial growth rates, depth, and surface salinity were weak but statistically significant. Umbellula encrinus is a long-lived species, vulnerable to various types of fishing gear, with a skeleton that stores biological and environmental information.