Symbiodiniaceae algal symbionts of Pocillopora damicornis larvae provide more carbon to their coral host under elevated levels of acidification and temperature.

Climate change destabilizes the symbiosis between corals and Symbiodiniaceae. The effects of ocean acidification and warming on critical aspects of coral survical such as symbiotic interactions (i.e.

Gene expression of Pocillopora damicornis coral larvae in response to acidification and ocean warming.

Objectives: The endosymbiosis with Symbiodiniaceae is key to the ecological success of reef-building corals. However, climate change is threatening to destabilize this symbiosis on a global scale. Most studies looking into the response of corals to heat stress and ocean acidification focus on coral colonies.

Particle-associated denitrification is the primary source of NO in oxic coastal waters.

The heavily human-perturbed coastal oceans are hotspots of nitrous oxide (NO) emission to the atmosphere. The processes underpinning the NO flux, however, remain poorly understood, leading to large uncertainties in assessing global NO budgets. Using a suite of nitrogen isotope labeling experiments, we show that multiple processes contribute to NO production throughout the estuarine-coastal gradient, sustaining intensive NO flux to the atmosphere.

Lineage-specific symbionts mediate differential coral responses to thermal stress.

Background: Ocean warming is a leading cause of increasing episodes of coral bleaching, the dissociation between coral hosts and their dinoflagellate algal symbionts in the family Symbiodiniaceae. While the diversity and flexibility of Symbiodiniaceae is presumably responsible for variations in coral response to physical stressors such as elevated temperature, there is little data directly comparing physiological performance that accounts for symbiont identity associated with the same coral host species. Here, using Pocillopora damicornis harboring genotypically distinct Symbiodiniaceae strains, we examined the physiological responses of the coral holobiont and the dynamics of symbiont community change under thermal stress in a laboratory-controlled experiment.

Pathways of NO production by marine ammonia-oxidizing archaea determined from dual-isotope labeling.

The ocean is a net source of the greenhouse gas and ozone-depleting substance, nitrous oxide (NO), to the atmosphere. Most of that NO is produced as a trace side product during ammonia oxidation, primarily by ammonia-oxidizing archaea (AOA), which numerically dominate the ammonia-oxidizing community in most marine environments. The pathways to NO production and their kinetics, however, are not completely understood.

Ambient nitrate switches the ammonium consumption pathway in the euphotic ocean.

Phytoplankton assimilation and microbial oxidation of ammonium are two critical conversion pathways in the marine nitrogen cycle. The underlying regulatory mechanisms of these two competing processes remain unclear. Here we show that ambient nitrate acts as a key variable to bifurcate ammonium flow through assimilation or oxidation, and the depth of the nitracline represents a robust spatial boundary between ammonium assimilators and oxidizers in the stratified ocean.

Assessing Catastrophes-Dragon-Kings, Black, and Gray Swans-for Science-Policy.

The threat of catastrophic incidents-from nonroutine events to extreme ones, such as Dragon-Kings (DK), Black Swans (BS), and Gray Swans-induces precautionary initiatives that, before the fact, may encounter public resistance or after the fact recriminations. This study develops three aspects of these events: (1) generating mechanisms, (2) the statistical distributions of near and far-term consequences, and (3) the aggregation of expert opinions about assumptions, mechanisms, and consequences that informs science-policy. This study shows how causal analysis should account for the: (1) nonlinear catastrophic behaviors that generate predictions, (2) common and power-law distributions of the consequences, (3) self-organizing criticality and self-similarity, and (4) feedbacks and couplings between mechanisms that produce snaps, crackles, and pops as precursor, warning signals.