Growth validation of gold coral Gerardia sp. in the Hawaiian Archipelago

Abstract

Colonies of the Hawaiian gold coral Gerardia sp. (n = 48) were measured, marked and then revisited 1 to 9 yr later to look for evidence of linear growth. The video images showed no change in the proportional size of the coral colonies relative to the marker pots left on the bottom and no change in the pattern of distal branches. Few of the measured delta values exceeded the error of our measurement technique, and the detected change in the sample was statistically indistinguishable from zero. Even though the temperature cycle in the coral beds appears seasonal, these observations indicate that gold coral growth is much slower than growth estimates derived from basal stem ring counts treated as annuli. The period of study was too short to effectively evaluate the validity of life span estimates from radiocarbon studies. The variability in radiocarbon data was assessed with broad sampling (n = 23) across study sites to reveal a mean life span of 950 yr with an overall radial growth of ~41 µm yr

Settlement, colonization, and succession patterns of gold coral Kulamanamana haumeaae in Hawaiian deep coral assemblages

“…The gold coral colony marked in the 2000 study (Parrish & Roark 2009) and then found toppled but alive in 2007 was half dead when it was revisited 5 yr later in 2012. Most of the underside polyps were absent, but since the coral toppled sometime between 5 and 12 yr earlier, it shows that the rates of tissue die-off can be slow.…”

“…A live gold coral colony marked standing in 2000 as part of a prior growth study (Parrish & Roark 2009) was revisited in 2007 and found toppled but fully alive. Left in place, it was revisited 5 yr later in 2012 to document any changes in its condition.…”

“…stem ring counts (Grigg 2002) and radiometric dating (Druffel et al 1995). Current estimates put the linear (or axial) growth of gold coral as slow as 2.2 mm yr −1 (Roark et al 2006, Parrish & Roark 2009, with the largest colonies estimated to be as much as 2700 yr in age. However, these growth estimates do not account for the parasitic aspect of gold coral's life history.…”

“…The mean axial growth of bamboo coral has been estimated at 0.14 to 1.38 cm yr −1 , which is equivalent to a life span between 70 and 126 yr (Roark et al 2005, Tracey et al 2007, Andrews et al 2009). The dependence of a slow-growing, long-lived parasitic coral on a faster-growing, shorter-lived host suggests that once a gold planula settles, it spreads across the host at a relatively quick pace (Parrish & Roark 2009). It is not known if an open portion of the host skeleton (e.g.…”

Variability in growth rates of long-lived black coral Leiopathes sp. from the Azores

“…is the zo anthid Gerardia sp. (lifespan in the order of millennia with growth rates as low as 5 µm yr −1 : Druffel et al 1995, Parrish & Roark 2009). …”