Cold-water Corals in the Mid-Atlantic Bight: Colony Morphology, Size, and Age

Sea whip corals Leptogorgia virgulata are a common structural component of benthic habitats found in the Mid-Atlantic region and an important component of habitat for commercially valuable fish, but are generally understudied. In addition, they are slow-growing, and easily damaged by fishing gear. We examined the colony complexity, length, age, and growth of sea whips from four sites in the Mid-Atlantic region to gain a better understanding of their biology in the area. There were no significant differences in the bifurcation (Rb) and tributary to source (T/S) ratios between sites, with the Rb ≈ 3 for all sites, indicating similar complexity between sites. The total length distribution was 8.3 cm to 85.3 cm, and 50% of corals in the range of 34.2-56.4 cm. Age, estimated from annual growth ring counts, ranged from 2 to 15 y, with 50% of corals in the range of 6 to 8 y. The large proportion of middle-sized and middle-aged corals suggests episodic recruitment. Age-length keys showed the trend of age increasing with total coral length, and a von Bertalanffy growth model estimated mean asymptotic size at 86.1 cm. This is the first study of sea whips in the coastal Mid-Atlantic region, and the information obtained will be a useful reference to study changes over time.

Below Leptogorgia colonies on a submerged wreck

Below: Cross section of Leptogorgia colony showing 9 growth rings.

Below: Black sea bass next to colonies of sea whips, Leptogorgia virgulata

Below: Rebecca Wenker records video of sea whip colonies.