Extreme tidal events are one of the most predictable natural disturbances in marine benthic habitats and are important determinants of zonation patterns in intertidal benthic communities. On coral reefs, spring low tides are recurrent disturbances, but are rarely reported to cause mass mortality. However, in years when extremely low tides coincide with high noon irradiances, they have the potential to cause widespread damage. Here, we report on such an event on a fringing coral reef in the central Great Barrier Reef (Australia) in September 2005. Visual surveys of colony mortality and bleaching status of more than 13,000 corals at 14 reef sites indicated that most coral taxa at wave-protected sites were severely affected by the event. Between 40 and 75% of colonies in the major coral taxa (Acropora, Porites, Faviidae, Mussidae and Pocilloporidae) were either bleached or suffered partial mortality. In contrast, corals at wave-exposed sites were largely unaffected (<1% of the corals were bleached), as periodic washing by waves prevented desiccation. Surveys along a 1–9 m depth gradient indicated that high coral mortality was confined to the tidal zone. However, 20–30% of faviid colonies were bleached throughout the depth range, suggesting that the increase in benthic irradiances during extreme low tides caused light stress in deeper water. Analyses of an 8-year dataset of tidal records for the area indicated that the combination of extended periods of aerial exposure and high irradiances occurs during May–September in most years, but that the event in September 2005 was the most severe. We argue that extreme low-tide, high-irradiance events are important structuring forces of intertidal coral reef communities, and can be as damaging as thermal stress events. Importantly, they occur at a time of year when risks from thermal stress, cyclones and monsoon-associated river run-off are minimal.
Coral Reef Great Barrier Reef Coral Community Coral Bleaching Coral Coloni
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
This is a preview of subscription content, log in to check access.
We thank D. Everett, A. Cole, J. Livingstone and J. Smith for assistance in the field and R. Pedersen and J. Broadbent (Maritime Safety Queensland) for providing the tidal data and A. Baird, M. Kosnik, W. Robbins and an anonymous reviewer for comments on the manuscript. The study was funded by the Australian Research Council through a Linkage grant. This is a contribution from the ARC Centre of Excellence for Coral Reef Studies.
Anthony KRN, Fabricius KE (2000) Shifting roles of heterotrophy and autotrophy in coral energetics under varying turbidity. J Exp Mar Biol Ecol 252:221–253CrossRefGoogle Scholar
Anthony KRN, Ridd PV, Orpin A, Larcombe P, Lough JM (2004) Temporal variation in light availability in coastal benthic habitats: effects of clouds, turbidity and tides. Limnol Oceanogr 49:2201–2211CrossRefGoogle Scholar
Anthony KRN, Connolly SR, Hoegh-Guldberg O (2007) Bleaching, energetics, and coral mortality risk: effects of temperature, light, and sediment regime. Limnol Oceanogr (in press)Google Scholar
Babcock RC, Bull GD, Harrison PL, Heyward AJ, Oliver JK, Wallace CC, Willis BL (1986) Synchronous spawning of 105 scleractinian coral species on the Great Barrier Reef. Mar Biol 90:379–394CrossRefGoogle Scholar
Baird AH, Marshall PA (2002) Mortality, growth and reproduction in scleractinian corals following bleaching on the Great Barrier Reef. Mar Ecol Prog Ser 237:133–141CrossRefGoogle Scholar
Barnes DJ, Chalker BE (1990) Calcification and photosynthesis in reef-building corals and algae. In: Dubinsky Z (ed) Ecosystems of the world: coral reefs. Elsevier, Amsterdam, pp 109–131Google Scholar
Berkelmans R (2002) Time-integrated thermal bleaching thresholds of reefs and their variation on the Great Barrier Reef. Mar Ecol Prog Ser 229:73–82CrossRefGoogle Scholar
Brown BE, Dunne RP, Scoffin TP, Le Tissier MDA (1994a) Solar damage in intertidal corals. Mar Ecol Prog Ser 105:219–230CrossRefGoogle Scholar
Brown BE, Le Tissier MDA, Dunne RP (1994b) Tissue retraction in the scleractinian coral Coeloseris mayeri, its effect upon coral pigmentation, and preliminary implications for heat balance. Mar Ecol Prog Ser 105:209–218CrossRefGoogle Scholar
Connell JH (1978) Diversity in tropical rain forrests and coral reefs. Science 199:1302–1310CrossRefGoogle Scholar
Connell JH, Hughes TP, Wallace CC (1997) A 30-year study of coral abundance, recruitment, and disturbance at several scales in space and time. Ecol Monogr 67:461–488CrossRefGoogle Scholar
Denny MW (1994) Extreme drag forces and the survival of wind- and water-swept organisms. J Exp Biol 194:97–115PubMedGoogle Scholar
Devantier LM, De'ath G, Turak E, Done TJ, Fabricius KE (2006) Species richness and community structure of reef-building corals on the nearshore Great Barrier Reef. Coral Reefs 25:329–340CrossRefGoogle Scholar
Dollar SJ (1982) Wave stress and coral community structure in Hawaii. Coral Reefs 1:71–81CrossRefGoogle Scholar
Done TJ (1982) Patterns in the distribution of coral communities across the central Great Barrier Reef. Coral Reefs 1:95–107CrossRefGoogle Scholar
van Duin EHS (2001) Modeling underwater light climate in relation to sedimentation, resuspension, water quality and autotrophic growth. Hydrobiologia 444:25–42CrossRefGoogle Scholar
Shick JM, Lesser MP, Jokiel PL (1996) Effects of ultraviolet radiation on corals and other coral reef organisms. Glob Change Biol 2:527–545CrossRefGoogle Scholar
Siebeck UE, Marshall NJ, Kluter A, Hoegh-Guldberg O (2006) Monitoring coral bleaching using a colour reference card. Coral Reefs 25:453–460CrossRefGoogle Scholar
Stapel J, Manuntun R, Hemminga MA (1997) Biomass loss and nutrient redistribution in an Indonesian Thalassia hemprichii seagrass bed following seasonal low tide exposure during daylight. Mar Ecol Prog Ser 148:251–262CrossRefGoogle Scholar