Non-river flood barium signals in the skeletons of corals from coastal Queensland, Australia

This combination of observations argues against an exogenous abiotic source for the anomalous Ba signal; instead, it may result from a biological event triggered by a combination of environmental parameters. Three hypotheses are presented, and critically tested against the observations: barite inclusion following phytoplankton blooms, decaying blooms of the blue-green algae Trichodesmium, and physiological perturbations associated coral mass spawning. None of the three hypotheses are fully consistent with all of the observations and it is concluded that no satisfactory explanation currently exists for the anomalous Ba spikes.