Low recruitment due to altered settlement substrata as primary constraint for coral communities under ocean acidification.

The future of coral reefs under increasing CO depends on their capacity to recover from disturbances. To predict the recovery potential of coral communities that are fully acclimatized to elevated CO, we compared the relative success of coral recruitment and later life stages at two volcanic CO seeps and adjacent control sites in Papua New Guinea. Our field experiments showed that the effects of ocean acidification (OA) on coral recruitment rates were up to an order of magnitude greater than the effects on the survival and growth of established corals.

Synergistic effects of diuron and sedimentation on photosynthesis and survival of crustose coralline algae.

Effects of short-term exposure to sedimentation and diuron, separately and in combination, on the photophysiology and survival of crustose coralline algae (CCA) were examined in controlled time-course experiments, using pulse-amplitude modulation (PAM) chlorophyll fluorometry. These experiments indicated that the effects of sediments and diuron, when applied in isolation, were often reversible, with recovery time dependent upon sediment type and diuron concentration. Exposure to fine (<63 microm grain size), nutrient-rich estuarine sediments reduced effective quantum yields (Delta F/F(m')) of photosystem II in CCA species more than exposure to the same amount of fine (<63 microm grain size) calcareous sediments.