Holocene sea level history and reef development in Hawaii and the equatorial Pacific Ocean

1. Holocene sea level history and reef development in Hawaii and the equatorial Pacific Ocean Eric E. Grossman Department of Geology and Geophysics Ph.D. Committee Chip Fletcher (chair) Richard Grigg (outside member) Fred Mackenzie Brian Popp Gordon Tribble

2. Richard Peltier (U. Toronto), Larry Edwards (U. Minnesota), ColinMurray-Wallace (U. Wollongong), Bruce Richmond (USGS), Golden Shadow SOEST-UH Faculty, especially Paul Wessel, Craig Glenn, Jane Tribble, Bob Grace ACKNOWLEDGMENTS The Coastal Hui Daily positive support Chris Conger Jodi Harney Geoff Garrison Clark Sherman John Rooney Kimball Millikan Laborious underwater assistance Wave spectra analyses Jerome Aucan Multispectral imagery Ebitari Isoun Paul Johnson Bruce Appelgate James Foster Data processing savvy Video footage Thomas Gorgas

3. A Special Thanksto Chip Fletcher

4. Who held on during the storm

5. My lovely fiancé Jodi

6. DEDICATION Mama Mia Arlene Hamblet

7. OUTLINE Introduction • Controls on reef accretion • Holocene sea level in the Pacific Peltier (1996), Grossman et al. (1998) • Holocene reef development on Oahu Methods Study Area Results • Modern community structure Grossman et al. (in review) • Holocene reef development Grossman and Fletcher (in review) Conclusions

8. Subsidence Theory(Darwin, 1842) Glacial Control Theory(Daly, 1915) Moorea,Tahiti Sea level

9. karst Karst Theoryand the role of antecedent topography(MacNeil, 1954; Purdy, 1974)

10. Controls on accretion Modified after Hubbard (1988)

11. Blanchon Holocene sea level Reef accretion histories record sea-level behavior Acropora palmata corals track sea level in the Caribbean (± 5-6m) Absence = Drowning during catastrophic rise events (CREs) coral community composition and zonation important proxy data

12. ICE-5G Pacific deglacial sea-level history • distinct from Caribbean • middle Holocene highstand +1-3 m + ICE-4G (Peltier, 1996) ICE-5G (Peltier in construction) reviewed by Grossman et al. (1998) * Uncertainties • no proven biotic indicators of sea level • role of wave energy? • reef initiation time • limited (single) analyses

13. Hawaiidifferential island tectonics and wave energy Variable relativesea-level histories • Wave base limits accommodation space• Variable effect on each island through time

14. OAHU Extensive terraces of fossil reef limestone Emerged fossil reef (>125 ka)(Stearns 1970; Muhs and Szabo, 1994) Submerged fossil reef (~210 ka)(Sherman et al. 1999) Holocene reef (<10 ka)(Easton and Olson, 1976; Grigg, 1998) Holocene reef (this study) KaneoheBay Kailua HanaumaBay

15. Hanauma Reef(Easton and Olson, 1976) Only detailed reef accretion history in Hawaii from an atypical wave-sheltered setting Low recovery (26% avg) in reef flat environment Shallow volcanic basement (<10 m) limits history (<7000 yr BP) Represents minimum sea level position, but a typical Hawaiian reef?

16. Hawaii sl - han Hanauma Reef (Easton and Olson, 1976) Accommodation space +2-3 m above reef (Montaggioni, 1988) Hawaii sea level including +1.75 m highstand at 3500 yr BP (Stearns, 1978; Grossman and Fletcher, 1998)

17. Hawaii sl - egdata Hanauma Reef (Easton and Olson, 1976) Accommodation space +2-3 m above reef (Montaggioni, 1988) Hawaii sea level including +1.75 m highstand at 3500 yr BP (Stearns, 1978; Grossman and Fletcher, 1998) Kailua Reef (this study) Windward reef accretion history is distinct from wave-sheltered Hanauma Bay.

18. Purpose • Analyze structure and zonation of modern reef community in a wave-exposed setting • Characterize internal composition and developmental history of a windward fringing reef • Assess the relative roles of sea-level history, wave energy and antecedent topography on reef accretion and resulting architecture • Move away from “fair-weather” studies and models of reef development

19. METHODS Bathymetric mapping Substrate mapping Drill coring Wave spectra measurements

20. Bathymetricmapping LIDAR (0-40 m) ~0.1 m vertical 1 m lateral Single beam (channel) ~0.01 m vertical ~0.1 m along track 6.5 m line space NOS (>40 m) 2-3 m vertical? ~30 m lateral

21. Substrate mapping Substrate types recorded along 30 m transects at 60 sites (-3 to -20 m depth) using Line Intercept Method Quantifies percent cover, colony counts, size, growth form, and diversity

22. Drill Coring X-Ray of coral skeleton

23. Drill Coring

24. Drill system in operation Courtesy of Thomas Gorgas

25. Wave heights and periods collected with directional Waverider buoys and pressure sensors Mokulua Isls. with Jerome Aucan Data available at Scripps web site: http://www.cdip.edu

26. STUDY AREA Windward Southeast Oahu Drowned paleochannel of Kawainui Stream Kawainui Channel Large sand-filed karst features in central back reef

27. Kailua ReefMapping sites Back reef (<5 m) North Platform (5-10 m) Seaward edge (10-13 m) Kawainui Channel Central Fore reef (13-20 m) Channel walls Central reef sites South

28. Kailua ReefDrill sites 32 cores water depths -3 to -20 m North Core lengths 0.5 to 18 m Kawainui Channel Central Recovery 76%, all cores 84%, 12 primary cores South Replicates cross-check recovered lithologies

29. Kailua ReefBathymetry Broad shelf 0 to -14 m North Narrow, gradual slope Central Hummocky, shallow South Very broad, smooth low slope

30. inner H

31. Kailua ReefWave climate N&NW swell Trade swell Kawainui Channel

32. Central fore reef (looking landward)Multispectral scanner imagery draped on bathymetry

33. Flythrough

34. Modern reef community structure Grossman, Fletcher, and Harney (in review) Variations in wave-related stress and antecedent topography govern the unique zonation and growth form response of reef building corals Importance: Understanding community structure and controls enables interpretation of fossil communities and paleoenvironments Ecotypes

35. Wave shoaling produces distinct niches

36. Cover and diversity

37. Species and form

38. Species and form

39. fore reef 1 1 -16 to -18 m FOV=4 m 2 2 -18 m FOV=5 m

40. Platy to encrusting -13 to -15 m FOV=20 m 1 Plasticity leads to higher diversity due to the added capacity to withstand stress 1 Porites lobata, Montipora capitata, M. patula 2 2 Ecotypes are more sensitive of environment than species alone -10 m FOV=2.5 m

41. Wt_mean depth

42. Colony ages Reef sub-communities maintained at different stages of development by wave-related stress and disturbance Persistent stress shapes composition Disturbance governs succession Moderate stress and disturbance leads to high diversity and greater age (K5, K4) High stress and excessive disturbance (waves and sediment abrasion) clears substrate and resets succession (K1) Century-scale turnover Colony Age = size / growth rate Growth rate = 1 cm/yr (Grigg, 1982)

43. Modern community structure summary Plasticity enables species to adapt to different levels of wave-related stress thereby increasing cover and diversity. Ecotypes are more sensitive indicators of environments than species alone. Variations in wave-related stress over a complex topography produce distinct cor-algal communities undergoing different rates of succession within a single reef system.

44. Holocene reef development Grossman and Fletcher (in review) Accommodation space for reef accretion may be strongly modulated through time by wave energy and its interaction with complex antecedent topography Importance: Distinct styles of architectural development and accretion occur within a single reef system Important implications for interpreting sea level

45. Kailua reefsurface

46. Internal Biolithofaciesin the 32 drill cores High Branching coral rudstone Encrusting cor-algalbindstone Mixed-skeletal rudstone/grainstone Massive coral framestone Branching coral framestone Mudstone/wackestone Depositional energy Low

47. Branching coral rudstone facies Strongly lithified rubble derived from fore reef Common in upper sections of central platform cores Middle to late Holocene

48. Encrusting bindstone facies Strongly bound encrusting coral and coralline algae Moderate to high bioerosion, rhodoliths present Common in upper sections of all cores Indicative of wave-swept platform communities

49. Mixed-skeletal rudstone/grainstone facies Strongly cemented fragments of all reef sediments Common in north central back reef and Flat Isl. Core Represents beach, high energy nearshore Middle to late Holocene and pre-Holocene

50. Massive coral framestone facies In situ Porites lobata Moderate bioerosion Common in lower sections of central platform cores Framework builder in depths of -10 to -14 m Early to middle Holocene