Growth rate for a zooxanthellate coral (Leptoseris hawaiiensis) at 90m

Abstract

In Hawaii, zooxanthellate corals of the genus Leptoseris have been observed growing in situ to depth over 150 m (Kahng et al. 2010). Due to clear oligotrophic waters and geological history, the main Hawaiian Islands have more potential area for zooxanthellate coral habitat at mesophotic depths than in shallow water ＜30 m (Locker et al. 2010). In the Indo-Pacific, Leptoseris spp. are among the most abundant zooxanthellate corals in the lower photic zone (Kahng et al. 2010). However, little is known about the life history traits of these dominant, deep-water corals. While slow me-tabolism and growth is a common strategy for survival in an energy-limited environment, whether deep-water zoox-anthellate corals adopt this strategy has not been previously studied. In October of 2006 and again in November of 2009, the same colony of Leptoseris hawaiiensis at 90 m in the Au'au Channel, Hawaii was measured with the aid of calibrated parallel lasers from the Hawaii Undersea Research Laboratory's Pisces IV submersible (Figure 1). The conserved spatial pattern of corallites on the colony (skeletal growth is outward but not upward) was used to verify measurements and account for parallax. Diameter of the colony increased 6.5±1.0 cm in 37 months. The average radial extension rate was 1.1±0.3 cm per year which is comparable to some shallow-water Growth rate for a zooxanthellate coral (Leptoseris hawaiiensis) at 90 m Photogallery Fig. 1 Two photos of the same colony of Leptoseris hawaiiensis growing at 90 m in 2006 (left) and again in 2009 (right). Horizontal distances between widest laser points are 16.4 cm (left) and 18.3 cm (right)