Deep-sea corals are a highly diverse group of marine organisms which are characterised by slow growth and extreme longevity. To better inform risk assessments for these deep-sea corals, a knowledge of their age and growth is key to understanding coral regeneration times following trawl disturbances or other damage.
This report presents outputs for year one of the CSP project POP2017-07 and includes a literature review describing the methods to age coral species, and a recommendation to obtain accurate age and growth data for key protected coral species.
The main methods applied to measure age and growth were: (1) direct observation, (2) enumeration of skeletal growth bands, (3) radiometric analyses. The advantages and disadvantages of each method were reviewed.
We recommend next steps for coral ageing research in the New Zealand region and detail a method most appropriate to apply to obtain accurate age and growth data for previously determined 'High Risk' protected coral species. The analytical method we suggest is radiocarbon dating of base and tip regions of the colony, combined with growth ring counts.
The recommendations build on the recent risk assessment that identified some deep-sea corals as being at high risk from the effects of bottom trawling. Most reef-building corals were assessed as medium risk, and cup and hydrocorals assessed as low risk. This is consistent with expectations. The research will address the risk assessment recommendations.
Tracey, D., Bostock, H., Shaffer, M. (2018). Ageing methods for protected deep-sea corals: A review and recommendation for an ageing study. DOC Contract 4527 GMC - Age & Growth of coral (POP2017-07). NIWA Client Report No. 2018035WN 40 p.