Maintaining natural spawning timing in Acropora corals following long distance inter-continental transportation

Abstract

The majority of research focusing on coral reproductive biology (e.g. spawning timing and synchrony) is carried out in facilities adjacent to reefs that the corals originated from. This is in part because transporting corals for long distances by air leads to sub-lethal stress that may confound the results of any experimental study. However, these constraints often mean research associated with coral reproductive timing is restricted to relatively few locations.

To assess the potential for studying environmental drivers of spawning timing in corals in captivity (defined here as ex situ closed aquaria), we aimed to transport 14 large (16-37 cm) Acropora hyacinthus colonies from reefs in Singapore to a closed aquarium system in London (a journey time of ~34 hours). Collection was purposefully timed to occur just before the predicted annual mass spawning event and on the day of transportation it was noted that 12 of the 14 corals contained large visible oocytes. The ‘inverted submersion method’ was applied and the water used for transport was buffered to ensure the colonies remained healthy throughout their travel time. At the end location all colonies were placed into a purpose built aquarium research system which allowed for the approximation of the environmental conditions found on the fringing reefs south of Singapore (the original location).

While three colonies appeared partially bleached (visibly pale) and one colony suffered from partial tissue loss, all colonies (i.e. 100% of those collected) were still alive at the time of writing (28 months post collection). More importantly, all corals that were gravid at the time of collection spawned ex situ within the same lunar month as those in the wild (within 3-4 nights of each other).

This paper describes the procedures for carrying out long distance transportation of large gravid broadcast spawning coral colonies from reef sites to public aquariums or research facilities around the world for the purpose of ex situ spawning research.