Long-term impacts of rising sea temperature and sea level on shallow water coral communities over a ~40 year period

Effects of combined rising sea temperature and increasing sea level on coral reefs, both factors associated with global warming, have rarely been addressed. In this ~40 y study of shallow reefs in the eastern Indian Ocean, we show that a rising relative sea level, currently estimated at ~11 mm y−1, has not only promoted coral cover but also has potential to limit damaging effects of thermally-induced bleaching. In 2010 the region experienced the most severe bleaching on record with corals subject to sea temperatures of >31 °C for 7 weeks. While the reef flats studied have a common aspect and are dominated by a similar suite of coral species, there was considerable spatial variation in their bleaching response which corresponded with reef-flat depth. Greatest loss of coral cover and community structure disruption occurred on the shallowest reef flats. Damage was less severe on the deepest reef flat where corals were subject to less aerial exposure, rapid flushing and longer submergence in turbid waters. Recovery of the most damaged sites took only ~8 y. While future trajectories of these resilient reefs will depend on sea-level anomalies, and frequency of extreme bleaching the positive role of rising sea level should not be under-estimated

Submarine landslides at the eastern Sunda margin: observations and tsunami impact assessment

Our analysis of new bathymetric data reveals six submarine landslides at the eastern Sunda margin between central Java and Sumba Island, Indonesia. Their volumes range between 1 km³ in the Java fore-arc basin up to 20 km³ at the trench off Sumba and Sumbawa. We estimate the potential hazard of each event by modeling the corresponding tsunami and its run-up on nearby coasts. Four slides are situated remarkably close to the epicenter of the 1977 tsunamigenic Sumba M w = 8.3 earthquake. However, comparison of documented tsunami run-up heights and arrival times with our modeling results neither allows us to confirm nor can we falsify the hypothesis that the earthquake triggered these submarine landslides