The effects of clove oil on coral: An experimental evaluation using Pocillopora damicornis (Linnaeus) Ashley J. Frisch a, ⁎ , Karin E. Ulstrup b,c , Jean-Paul A. Hobbs a a School of Marine and Tropical Biology, and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld 4811, Australia b Institute for Water and Environmental Resource Management and Department of Environmental Science, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia c Australian Institute of Marine Science, PMB No. 3, Townsville MC, QLD 4810, Australia Received 18 December 2006; received in revised form 2 February 2007; accepted 7 February 2007 Abstract Clove oil solution (10% clove oil, 90% ethanol) is an anaesthetic that is widely used to catch demersal fish on coral reefs. This study assessed the effects of clove oil solution on colonies of Pocillopora damicornis, a cosmopolitan reef coral. In the laboratory, low concentrations (0.5 ppt) of clove oil solution had no effect on coral colour or photosynthetic efficiency, irrespective of exposure time (1–60 min). Corals treated with high concentrations (50 ppt) of clove oil solution died immediately, including those that were exposed briefly (1 min). Intermediate concentrations (5 ppt) of clove oil solution produced variable results: a 1 min exposure had no effect, a 10 min exposure caused bleaching and reduced photosynthetic efficiency, and a 60 min exposure caused total mortality. To validate these observations, clove oil solution was applied to corals in situ. Sixty-three days after application, corals treated with 10 ml of clove oil solution appeared to be unaffected. It was concluded that (1) limited amounts of clove oil solution are unlikely to harm this coral, and (2) clove oil solution may represent an ‘eco-friendly’ alternative to cyanide for use in the live reef-fish trade. © 2007 Elsevier B.V. All rights reserved. Keywords: Anaesthetic; Clove oil; Coral; Eugenol; Live reef-fish trade; Pocillopora damicornis 1. Introduction Many of the world's coral reefs are found in devel- oping nations where reef fisheries are heavily relied upon as a source of food and income (McManus, 1997; Wilkinson, 2004). Over recent decades however, stocks of many reef fishes have become severely depleted, such that traditional fishing methods are no longer effective or profitable (Jackson et al., 2001; Wilkinson, 2004). Faced with few alternatives, many fishers resort to destructive fishing practices (Pauly, 1994). This is particularly evi- dent in the South–East Asian live reef-fish trade, where the depletion of fish stocks across vast areas has led to the broadscale misuse of cyanide (Johannes and Riepen, 1995; McManus, 1997). Cyanide fishing began in the Philippines in the early 1960s, and has since spread to at least 15 other countries (Rubec, 1986; McManus, 1997). The technique itself involves the dissolution of sodium cyanide tablets in water (30–120 g l - 1 ), which is subsequently ‘squirted’ across benthic coral communities using small plastic bottles (Johannes and Riepen, 1995; Pet, 1997). Fish that are exposed to the milky solution are rapidly asphyxiated, Journal of Experimental Marine Biology and Ecology 345 (2007) 101 – 109 www.elsevier.com/locate/jembe ⁎ Corresponding author. Tel.: +61 7 47816273; fax: +61 7 47251570. E-mail address: ashley.frisch@jcu.edu.au (A.J. Frisch). 0022-0981/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jembe.2007.02.004