We test for trace element proxies in the high-magnesium calcite fraction of bamboo coral internodes by comparing environmental conditions and growth rates to the specimen-mean compositions of 73 corals that were live-caught at depths ranging from 3 to 3950 m and collected from habitats ranging from tropical coral reefs to the Antarctic slope.Comparisons were done at a large geographic scale (LGS) and for a well sampled area south of Australia, across depths at a single site, in order to help separate the effects of environmental variables that co-vary at one spatial scale, but not the other
Skeletal growth records in annually banded massive coral skeletons are an under-exploited archive of coral responses to environmental changes. Average linear extension and calcification rates in Indo-Pacific Porites are linearly related to average water temperatures through 23 to 30¯C. Assessing long-term trends in Porites extension and density requires caution as there is evidence of an age effect whereby in earlier growth years corals will tend to extend less and form a higher density skeleton than in later years. This does not appear to affect calcification rates.
The oceans are becoming more acidic due to absorption of anthropogenic carbon dioxide from the atmosphere. The impact of ocean acidification on marine ecosystems is unclear, but it will likely depend on species adaptability and the rate of change of seawater pH relative to its natural variability. To constrain the natural variability in reef-water pH, we measured boron isotopic compositions in a similar to 300-year-old massive Porites coral from the southwestern Pacific.