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Distinguished Speaker Zonneveld talks "Coral Reefs in Murky Water Settings"

EES welcomes Distinguished Speaker Dr. John-Paul Zonneveld, University of Alberta, Canada.

"Coral Reefs in murky water settings: diverse and robust reef successions in turbid water settings on the southern fringe of the coral triangle"

October 25, 2019 12:30 PM, Room 204, Natural Science Building

Coral reefs are the most diverse ecosystems in recent and modern marine settings yet are exceptionally sensitive to changes in environmental parameters such as seawater temperature, turbidity, ocean pH, sea level fluctuations and changes in storm intensity and frequency. Of these stressors, thermal stress may have the most severely deleterious effects (eg. up to 30% of coral in the Great Barrier Reef, NE Australia was killed during the 2015-2016 bleaching event). Most reef research has focussed on archetypal clear water reef systems however reefs are common in some turbid water settings (eg, delta fronts, estuaries, macrotidal coasts) as well. Although turbidity has long been viewed as a source of stress on corals, recent analyses have argued that moderate levels of turbidity may lower reef stress by shielding coral taxa from exceptionally high solar flux.

The northeastern coast of Sumba, East Nusa Tengarra, Indonesia, between Tanjung Laundi and Tanjung Watuata occurs within the heart of the coral triangle and provides a natural laboratory within which to test the importance of turbid environments for corals and coral reefs. This coast consists of a ~475 metre thick succession of uplifted coral reef terraces. Previous studies have shown that these terraces were uplifted over the past ~1,000,000 years and provides an approximately continuous record of reef development in northeastern Sumba during the late Pleistocene and Holocene. To date, this study has focussed on reefs within the Waingapu Bay –Kambinaru River Valley area. The Kambinaru River system incises through the Laundi-Watuata terrace system. It has been active since at least the early Pleistocene and delivers siliclastics sand, silt and clay sourced in from sedimentary and volcanic strata in the Matawai La Pawu highlands in the southern part of the island. The Kambinaru mouth debouches into Waingapu Bay on the Savu Sea where it forms a seasonally deltaic complex that is flow-dominated for a short portion of each year and wave-dominated for the rest. Despite considerable turbidity, moderate-sized coral reefs occur within, and adjacent to, the modern delta complex. Analysis of Pleistocene outcrop in the Kambinaru Valley area show that reefs occurred interstratified with fluvial-deltaic-dominated areas throughout the Pleistocene. Coral reef successions within the Kambinaru embayment include 10-45% siliciclastic silt, sand and gravel. Reef limestone units sampled from open-ocean (clear water) palaeo-settings at Tanjung Laundi typically consist of <5% clastic detritus. Reef systems on open coastal settings are generally diverse (referred to here as equilibrium reefs) however several low-diversity reef systems characterized by comparatively few coral taxa and common coralline algae also occur in clear water settings and are interpreted as local coral extirpation events (referred to here as crisis reef). Coeval turbid-water reefs, although less diverse than equilibrium reefs in clear water settings, maintain diversity during crisis intervals.  Preliminary evidence suggests that Pleistocene turbid-system coral reefs in Sumba acted as refugia wherein corals and associated biota survived ecological crises that decimated temporally equivalent open ocean / clear water reefs.

John-Paul Zonneveld is a Professor in the Department of Earth and Atmospheric Sciences at the University of Alberta, curator of the University of Alberta drill core collection and SEPM Special Publications Editor.  John-Paul has been with the University of Alberta for 12 years.  Prior to this John-Paul was a Research Geologist with the Geological Survey of Canada. John-Paul graduated with his B.Sc. from Calvin College (1988), M.Sc. from Michigan State University (1994) and Ph.D. from the University of Alberta (1999).

John-Paul’s research is focused in the areas of sedimentology, stratigraphy, palaeoecology and palaeontology. John-Paul’s research projects are typically multidisciplinary and commonly focus on problems involving the interface between geological and biological system.  Current projects include: mixed siliciclastic-carbonate depositional systems; biotic recovery in marine systems after the Permian-Triassic extinction; the sedimentology, biostratigraphy and paleoecology of Early to Middle Eocene successions in southwestern Wyoming; and the Paleogene to Quaternary paleontology and sedimentology of Island Southeast Asia (focusing on Sumatra, Kalimantan, Sumba, Bali and Timor).



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