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Bessell-Browne P, Negri AP, Fisher R, Clode PL, Jones R. Impacts of light limitation on corals and crustose coralline algae. Sci Rep 2017; 7:11553. [PMID: 28912462 PMCID: PMC5599546 DOI: 10.1038/s41598-017-11783-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 08/30/2017] [Indexed: 11/30/2022] Open
Abstract
Turbidity associated with elevated suspended sediment concentrations can significantly reduce underwater light availability. Understanding the consequences for sensitive organisms such as corals and crustose coralline algae (CCA), requires an understanding of tolerance levels and the time course of effects. Adult colonies of Acropora millepora and Pocillopora acuta, juvenile P. acuta, and the CCA Porolithon onkodes were exposed to six light treatments of ~0, 0.02, 0.1, 0.4, 1.1 and 4.3 mol photons m-2 d-1, and their physiological responses were monitored over 30 d. Exposure to very low light (<0.1 mol photons m-2 d-1) caused tissue discoloration (bleaching) in the corals, and discolouration (and partial mortality) of the CCA, yielding 30 d EI10 thresholds (irradiance which results in a 10% change in colour) of 1.2-1.9 mol photons m-2 d-1. Recent monitoring studies during dredging campaigns on a shallow tropical reef, have shown that underwater light levels very close (~500 m away) from a working dredge routinely fall below this value over 30 d periods, but rarely during the pre-dredging baseline phase. Light reduction alone, therefore, constitutes a clear risk to coral reefs from dredging, although at such close proximity other cause-effect pathways, such as sediment deposition and smothering, are likely to also co-occur.
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Affiliation(s)
- Pia Bessell-Browne
- Australian Institute of Marine Science, Townsville, QLD, and Perth, WA, Australia.
- The Oceans Institute and The Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia.
- Western Australian Marine Science Institution (WAMSI), Perth, WA, Australia.
| | - Andrew P Negri
- Australian Institute of Marine Science, Townsville, QLD, and Perth, WA, Australia
- Western Australian Marine Science Institution (WAMSI), Perth, WA, Australia
| | - Rebecca Fisher
- Australian Institute of Marine Science, Townsville, QLD, and Perth, WA, Australia
- Western Australian Marine Science Institution (WAMSI), Perth, WA, Australia
| | - Peta L Clode
- The Oceans Institute and The Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia
| | - Ross Jones
- Australian Institute of Marine Science, Townsville, QLD, and Perth, WA, Australia
- Western Australian Marine Science Institution (WAMSI), Perth, WA, Australia
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Murphy JWA, Richmond RH. Changes to coral health and metabolic activity under oxygen deprivation. PeerJ 2016; 4:e1956. [PMID: 27114888 PMCID: PMC4841221 DOI: 10.7717/peerj.1956] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 03/31/2016] [Indexed: 11/20/2022] Open
Abstract
On Hawaiian reefs, the fast-growing, invasive algae Gracilaria salicornia overgrows coral heads, restricting water flow and light, thereby smothering corals. Field data shows hypoxic conditions (dissolved oxygen (DO2) < 2 mg/L) occurring underneath algal mats at night, and concurrent bleaching and partial tissue loss of shaded corals. To analyze the impact of nighttime oxygen-deprivation on coral health, this study evaluated changes in coral metabolism through the exposure of corals to chronic hypoxic conditions and subsequent analyses of lactate, octopine, alanopine, and strombine dehydrogenase activities, critical enzymes employed through anaerobic respiration. Following treatments, lactate and octopine dehydrogenase activities were found to have no significant response in activities with treatment and time. However, corals subjected to chronic nighttime hypoxia were found to exhibit significant increases in alanopine dehydrogenase activity after three days of exposure and strombine dehydrogenase activity starting after one overnight exposure cycle. These findings provide new insights into coral metabolic shifts in extremely low-oxygen environments and point to ADH and SDH assays as tools for quantifying the impact of hypoxia on coral health.
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Affiliation(s)
- James W A Murphy
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii at Manoa , Honolulu, HI , United States
| | - Robert H Richmond
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii at Manoa , Honolulu, HI , United States
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Jones R, Bessell-Browne P, Fisher R, Klonowski W, Slivkoff M. Assessing the impacts of sediments from dredging on corals. MARINE POLLUTION BULLETIN 2016; 102:9-29. [PMID: 26654296 DOI: 10.1016/j.marpolbul.2015.10.049] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/19/2015] [Accepted: 10/22/2015] [Indexed: 06/05/2023]
Abstract
There is a need to develop water quality thresholds for dredging near coral reefs that can relate physical pressures to biological responses and define exposure conditions above which effects could occur. Water quality characteristics during dredging have, however, not been well described. Using information from several major dredging projects, we describe sediment particle sizes in the water column/seabed, suspended sediment concentrations at different temporal scales during natural and dredging-related turbidity events, and changes in light quantity/quality underneath plumes. These conditions differ considerably from those used in past laboratory studies of the effects of sediments on corals. The review also discusses other problems associated with using information from past studies for developing thresholds such as the existence of multiple different and inter-connected cause-effect pathways (which can confuse/confound interpretations), the use of sediment proxies, and the reliance on information from sediment traps to justify exposure regimes in sedimentation experiments.
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Affiliation(s)
- Ross Jones
- Australian Institute of Marine Science (AIMS), Perth, Australia; Western Australian Marine Science Institution, Perth, Australia.
| | - Pia Bessell-Browne
- Australian Institute of Marine Science (AIMS), Perth, Australia; Centre of Microscopy, Charaterisation and Analysis, The University of Western Australia, Perth, Australia; Western Australian Marine Science Institution, Perth, Australia
| | - Rebecca Fisher
- Australian Institute of Marine Science (AIMS), Perth, Australia; Curtin University, Bentley, Perth, Australia
| | - Wojciech Klonowski
- Curtin University, Bentley, Perth, Australia; In situ Marine Optics, Bibra Lake, Perth, Australia
| | - Matthew Slivkoff
- Curtin University, Bentley, Perth, Australia; In situ Marine Optics, Bibra Lake, Perth, Australia
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Michaelidis B, Storey KB. Anaerobiosis and the regulation of glycolytic enzymes in the sea anemoneMetridium senile. ACTA ACUST UNITED AC 1990. [DOI: 10.1002/jez.1402560205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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