Photophysiological stress in scleractinian corals in response to short-term sedimentation

Effects of short-term sedimentation on common coastal coral species were investigated in laboratory and field experiments on the Great Barrier Reef (GBR) using pulse-amplitude modulated (PAM) chlorophyll fluorometry. In the laboratory, changes in maximal quantum yields of photosystem II (Fv/Fm) in Montipora peltiformis were examined in response to the amount of sedimentation (79–234 mg cm−2) and duration of exposure (0–36 h). In control colonies, Fv/Fm ranged from 0.67 to 0.71, and did not show any temporal trend, while maximum yields of sediment-covered fragments declined steadily and reached levels below 0.1 in most colonies after 36 h coverage. Maximal quantum yield in M. peltiformis declined linearly in relation to both the amount of sediment deposited per unit surface area and the duration of exposure. Zooxanthellae densities and chlorophyll concentrations per unit area of sediment-treated corals decreased in the same manner, however, their responses were not quite as strong as the changes in Fv/Fm. Within the ranges measured, sedimentation stress of colonies exposed to large amounts of sediment for short periods of time was similar to that exposed to low amounts of sediments for prolonged periods of time. Colonies were recovered from short-term, or low-level, sedimentation within <36 h, whereas long-term exposure, or high levels of sedimentation, killed exposed colony parts. Field experiments comparing susceptibilities of common coastal coral species towards sedimentation showed significant reductions in effective quantum yields (ΔF/Fm′) in 9 out of 12 common coastal species after 22 h of exposure. Three out of twelve investigated species were not affected by the experimental application of sediments (Galaxea fascicularis, Fungia crassa, and Pectinia lactuca). Our results suggest that anthropogenic sediment deposition can negatively affect the photosynthetic activity of zooxanthellae and thus the viability of corals. However, the results also showed the ability of corals to compartmentalise sedimentation stress, as the photosynthetic activity only from tissues directly underneath the sediment declined, whereas that of adjacent clean tissues did not change measurably.

[1]  M. Stafford-Smith.  Sediment-rejection efficiency of 22 species of Australian scleractinian corals , 1993 .

[2]  J. Gilmour,et al.  Experimental investigation into the effects of suspended sediment on fertilisation, larval survival and settlement in a scleractinian coral , 1999 .

[3]  Michael Kühl,et al.  Microenvironment and photosynthesis of zooxanthellae in scleractinian corals studied with microsensors for O2, pH and light , 1995 .

[4]  E. Peters,et al.  A comparative study of the effects of sedimentation on symbiotic and asymbiotic colonies of the coral Astrangiadanae Milne Edwards and Haime 1849 , 1985 .

[5]  S. Coles,et al.  Response of Hawaiian and other Indo-Pacific reef corals to elevated temperature , 1990, Coral Reefs.

[6]  J. Vermaat,et al.  Damage and recovery of four Philippine corals from short-term sediment burial , 1999 .

[7]  S. Beer,et al.  In situ measurements of photosynthetic irradiance responses of two Red Sea sponges growing under dim light conditions , 1998 .

[8]  Lauretta Burke,et al.  Reefs at Risk in Southeast Asia , 2002 .

[9]  Clive Wilkinson,et al.  Status of Coral Reefs of the World: 2020 , 2000 .

[10]  G. M. Branch,et al.  Effects of sediment on the energy budgets of four scleractinian (Bourne 1900) and five alcyonacean (Lamouroux 1816) corals , 1995 .

[11]  G. Hodgson.  Tetracycline reduces sedimentation damage to corals , 1990 .

[12]  W. Giesen,et al.  Sabaki River sediment load and coral stress: correlation between sediments and condition of the Malindi-Watamu reefs in Kenya (Indian Ocean) , 1993 .

[13]  D. Hubbard.  Sedimentation as a control of reef development: St. Croix, U.S.V.I. , 1986, Coral Reefs.

[14]  B. Riegl.  Effects of sand deposition on scleractinian and alcyonacean corals , 1995 .

[15]  R. Bak,et al.  Patterns of Oil-Sediment rejection in corals , 1976 .

[16]  G. Smith,et al.  Effects of particulate peat on the behavior and physiology of the Jamaican reef-building coral Montastrea annularis , 1982 .

[17]  O. Hoegh‐Guldberg,et al.  PAM Chlorophyll Fluorometry: a New in situ Technique for Stress Assessment in Scleractinian Corals, used to Examine the Effects of Cyanide from Cyanide Fishing , 1999 .

[18]  John J. Cullen,et al.  Sunlight and water transparency: cornerstones in coral research , 2002 .

[19]  P. Ralph,et al.  In situ underwater measurements of photosynthetic activity of coral zooxanthellae and other reef-dwelling dinoflagellate endosymbionts , 1999 .

[20]  K. Fabricius,et al.  Rapid Smothering of Coral Reef Organisms by Muddy Marine Snow , 2000 .

[21]  Russ Babcock,et al.  Effects of sedimentation on settlement of Acropora millepora , 2004, Coral Reefs.

[22]  O. Hoegh‐Guldberg,et al.  Changes in quantum efficiency of Photosystem II of symbiotic dinoflagellates of corals after heat stress, and of bleached corals sampled after the 1998 Great Barrier Reef mass bleaching event , 2000 .

[23]  Mark E. Warner,et al.  The effects of elevated temperature on the photosynthetic efficiency of zooxanthellae in hospite from four different species of reef coral: a novel approach , 1996 .

[24]  R. Bak.  Lethal and sublethal effects of dredging on reef corals , 1978 .

[25]  R. Dodge,et al.  Coral Populations and Growth Patterns: Responses to Sedimentation and Turbidity Associated with Dredging , 1977 .

[26]  C. Rogers,et al.  Sublethal and lethal effects of sediments applied to common Caribbean Reef corals in the field , 1983 .

[27]  W. Dennison,et al.  Physiological Responses of Five Seagrass Species to Trace Metals , 2000 .

[28]  B. Mapstone,et al.  The fringing reefs of Magnetic Island : benthic biota and sedimentation - a baseline study: a report to the Great Barrier Reef Marine Park Authority , 1992 .

[29]  S. Neudecker.  Growth and survival of scleractinian corals exposed to thermal effluents at Guam , 1981 .

[30]  C. Rogers.  Responses of coral reefs and reef organisms to sedimentation , 1990 .

[31]  O. Hoegh‐Guldberg,et al.  Diurnal changes in the photochemical efficiency of the symbiotic dinoflagellates (Dinophyceae) of corals: photoprotection, photoinactivation and the relationship to coral bleaching , 2001 .

[32]  Eric Wolanski,et al.  Effects of transparent exopolymer particles and muddy terrigenous sediments on the survival of hard coral recruits , 2003 .

[33]  K. Fabricius,et al.  Shifting roles of heterotrophy and autotrophy in coral energetics under varying turbidity. , 2000, Journal of experimental marine biology and ecology.

[34]  B. Riemann,et al.  Ecological consequences of dredging and bottom trawling in the Limfjord, Denmark. , 1991 .

[35]  P. Edmunds,et al.  The oxygen microenvironment adjacent to the tissue of the scleractinian Dichocoenia stokesii and its effects on symbiont metabolism , 1999 .

[36]  N. Shashar,et al.  Extreme Diel Fluctuations of Oxygen in Diffusive Boundary Layers Surrounding Stony Corals. , 1993, The Biological bulletin.

[37]  W. Bilger,et al.  Continuous recording of photochemical and non-photochemical chlorophyll fluorescence quenching with a new type of modulation fluorometer , 2004, Photosynthesis Research.

[38]  G. F. Humphrey,et al.  New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton , 1975 .

[39]  H. Lasker.  Sediment rejection by reef corals: The roles of behavior and morphology in Montastrea cavernosa (Linnaeus) , 1980 .

[40]  R. Ormond,et al.  Sediment-rejection mechanisms of 42 species of Australian Scleractinian corals , 1992 .

[41]  J. Brodie,et al.  Flood plumes in the Great Barrier Reef : spatial and temporal patterns in composition and distribution , 2001 .