Short-term impacts of the invasive Indo-Pacific lionfish on Bahamian coral-reef fish communities
Download ReportTranscript Short-term impacts of the invasive Indo-Pacific lionfish on Bahamian coral-reef fish communities
Short-term impacts of the invasive Indo-Pacific lionfish on Bahamian coral-reef fish communities Research by Megan Cook Advised by Dr. Mark Hixon & Mark Albins, OSU Zoology Pterois volitans • Native to Indo-Pacific • Eat fishes & crustaceans • Found up to 100m deep • Introduced to SE Florida in early 1990’s Establishment and Spread Biscayne Bay, FL Hurricane Andrew, 1992 2000-2007 1990’s ? ? Hare and Whitfield 2003, Whitfield et al 2007, Snyder and Burgess 2007, personal communication - Lad Akins, REEF. Map created using Google Earth™ ? Perry Institute for Marine Science Lee Stocking Island, Bahamas Exuma Sound, Bahamas 1991-2004 - 0 2005 - 1 2006 - 2 2007 - 107 2008 - 153 (3 weeks) Exuma Sound Lee Stocking Island Regularly visited sites Reasons for Concern • Rapid spread • Caribbean reefs degraded, overfished • Novel predation style • Few natural predators • Venomous spines • Large & abundant • Marine fish introductions are rarely successful Major Questions of the Invasion 1. What organisms are being eaten? 2. Do lionfish have predators in this new ecosystem? 3. With which native species (if any) are lionfish competing? Major Questions of the Invasion 1. What organisms are being eaten? 2. Do lionfish have predators in this new ecosystem? 3. With which native species (if any) are lionfish competing? Stomach Contents • Of 52 fish examined… – 48 with identifiable prey – 47 with bony fish parts • 25 ate fish only – 23 with crustacean parts • 1 ate crustaceans only • 11 identifiable species found from 8 families • Mixed effects, multifactor ANOVA – Significant lionfish effect, p = 0.037 • 79% reduction in net recruitment by week 5 • 23 of 38 spp. negatively affected by lionfish - including 5 of 7 herbivorous spp. Mean net recruitment (+/- SEM) Predation Impacts Control reefs Lionfish reefs 40 30 20 10 0 1 2 3 4 5 Time post-manipulation (weeks) Albins, M.A. and M.A. Hixon. (2008). Invasive Indo-Pacific lionfish (Pterois volitans) reduce recruitment of Atlantic coral-reef fishes. Marine Ecology Progress Series. In Press. Major Questions of the Invasion 1. What organisms are being eaten? 2. Do lionfish have predators in this new ecosystem? 3. With which native species (if any) are lionfish competing? Predation in Literature • Predators in native range largely unknown • One coronetfish in Israel found with 10cm lionfish ingested1 • Anecdotal evidence of cannibalism • Only one published account of predation in the Bahamas: 47.2cm (SL) tiger grouper ate a 6.1cm lionfish2 1. Bernadsky, G. and D. Goulet. (1991). A Natural Predator of the Lionfish, Pterois miles. Copeia. 1, 230-231. 2. Maljkovic, A. and T.E. Van Leeuwen. (2008). Predation on the invasive red lionfish, Pterois volitans (Pisces: Scorpaenidae), by native groupers in the Bahamas. Coral Reefs. 27(3), 501. Predator Trials • Captured five local predatory species (7-46 cm TL) - 1 Caribbean Octopus (Octopus briareus) - 2 Nurse Shark (Ginglymostoma cirratum) - 1 Red Hind (Epinephelus guttatus) - 3 Nassau Grouper (Epinephelus striatus) - 3 Graysby (Epinephelus cruentatus) • Fed once for acclimation, then offered a 4-10 cm TL lionfish as potential prey Predator Trials • No native predators ate a lionfish • Nassau groupers spent 39 days without eating their lionfish • Red Hind ate a toxic soapfish but did not attack lionfish Major Questions of the Invasion 1. What organisms are being eaten? 2. Do lionfish have predators in this new ecosystem? 3. With which native species (if any) are lionfish competing? Coney grouper • Common reef predator • Similar size to lionfish • Easy to capture • Rapid predatory strike: dart from shelter and immediately return • Usually found in complex habitats Experimental Design • 21, 6.5 ft3 aquaria with rock habitat at center • 7 statistical blocks with 3 treatments each: Coney alone (CX), Lionfish alone (LX), Coney and Lionfish together (LC) – Blocks assigned by fish size • Feeding trials every other day: CX & LX- 2 fish, LC- 4 fish • Growth, feeding efficiency, and _ consumption time recorded Hypothesis • If lionfish are adversely affecting coney grouper, then the growth rate of the native predator and average consumption per feeding will be lower in the presence of lionfish than in the coney-alone treatment. Results: Growth • As expected, CX treatment averaged a greater growth rate than CL but not significantly • t-test, p=0.935 Average Length Growth Rate . • Lionfish grew more than twice the rate of coney grouper Growth Rate (cm/day) +/- SEM 0.03 0.025 0.02 0.015 0.01 0.005 0 Coney Alone Coney with Lion Lion Alone Results: Growth • Coney grouper grew poorly regardless of treatment. • t-test, p=0.741 . +/- SEM Growth Rate (g/day) •No significant difference between growth rate of coney alone or lion-coney treatment Average Weight Growth Rate 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 -0.01 -0.02 -0.03 Coney Alone Coney with Lion Lion Alone Results: Feeding +/- SEM Prey consumption Average Consumption per Feeding 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 • Coneys with lions ate fewer prey -inhibited by presence of 2nd predator • No significant difference between coney feeding performance • t-test, p=0.563 Coney Alone Coney with Lion • Lionfish averaged greater consumption than coneys in all treatment A Serious Problem for the Atlantic • Faster growth rate than native predators – t-test, p= 0.014 • Higher consumption rate than natives • Higher resilience: 17 coney deaths in 1 mo – found live lion with healing spear hole through it • Complete eradication unlikely Average Length Growth Rate +/-+/(cm/day) Growth SEM GrowthRate Rate (cm/day) SEM • Population growing exponentially 0.025 0.02 0.015 0.01 0.005 0 Coney Lionfish • Special thanks to: The HHMI organization, the National Science Foundation, COS Cripps Scholarship Fund, Dr. Mark Hixon, Mark Albins, Darren Johnson, Flower Moye, Tim Pusack, Dr. Kevin Ahern, Brenda Gadd and the staff of PIMS Short-term impacts of the invasive Indo-Pacific lionfish on Bahamian coral-reef fish communities Research by Megan Cook Advised by Dr. Mark Hixon & Mark Albins, OSU Zoology