Symbionts Impact the Behavior of Coral Larvae

by Kimberly Coombs

Climate change is known for causing adults corals to become bleached, but it is also affecting the early life stages of corals. The larval stage of a coral reef’s lifecycle is very important to its survivorship. Corals disperse their larvae out into the water, then the larvae are responsible for finding a suitable substrate to settle on. After settlement, corals are able to start growing accumulate symbionts. Several studies have observed how different symbionts influence juvenile coral growth rates and thermotolerance; however, no data currently show if there are any influences from symbionts on the coral larvae before settlement occurs. Continue reading

Algal Symbionts may make Corals Resistant to Rising Sea Temperatures

by Kimberly Coombs

Corals share a mutualistic relationship with algal symbionts, but with increasing sea temperatures, these symbionts become expelled from the coral. The loss of symbionts causes the corals to become bleached and there have been declines of coral cover worldwide. Recent research has shown that there may be symbionts that are thermotolerant, such as the genus Symbiodinium, which may help reduce the amount of bleaching episodes seen amongst corals. Symbiodinium is divided into nine subgeneric clades, A-I, and the Symbiodinium D1a has been documented showing thermotolerance. Continue reading

Can Corals Acclimate to Large Temperature Changes?

by Dawn Barlow

Over just the past few decades ocean temperature has contributed to significant losses in global coral cover, and the extent to which corals can undergo physiological acclimatization or genetic adaptation to thermal changes remains uncertain. However, this information will be crucial for the effectiveness of conservation strategies and accuracy of projections of reef futures. This study conducted by Howells et al. (2013) investigates the potential for corals to acclimatize to temperatures that exceed historical thermal regimes. This is done by investigating several parameters—bleaching, mortality, Symbiodinium type fidelity, and reproductive timing—in coral colonies that have been transplanted between warm central regions and cool southern regions of the Great Barrier Reef for a period of 14 months. Continue reading