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Marine Ecology Progress Series

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MEPS 350:193-207 (2007)  -  DOI:

Response of deep-sea scavengers to ocean acidification and the odor from a dead grenadier

James P. Barry1,*, Jeffrey C. Drazen2

1Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, California 95039, USA
2University of Hawaii, Department of Oceanography, MSB 606, 1000 Pope Rd, Honolulu, Hawaii 96822, USA

ABSTRACT: Experiments to assess the impact of ocean acidification on abyssal animals were performed off Central California. The survival of caged megafauna (Benthoctopus sp., Pachycara bulbiceps, Coryphaenoides armatus) exposed to CO2-rich and normal (control) seawater varied among species. Benthoctopus sp. and P. bulbiceps survived control conditions and month-long episodic exposure to acidic, CO2-rich waters (pH reductions of ~0.1 U). All C. armatus in both treatments died, potentially due to cage-related stress, predation, and exposure to acidic waters. High survival by P. bulbiceps and Benthoctopus under month-long exposure to CO2-rich waters indicates a physiological capacity to cope, at least temporarily, with stresses that will accompany expected future changes in ocean chemistry. The abundance of free-ranging scavengers was not correlated with variation in pH levels near fish cages. Incidental observations of abyssal scavengers collected using time-lapse cameras during these experiments were used secondarily to evaluate the hypothesis that macrourid fishes avoid the odor of dead conspecifics. Caged macrourids in view of time-lapse cameras died within 2 to 3 d, eliciting a strong response from the regional scavenger assemblage which aggregated near the cage. The pattern of scavenger visits suggests avoidance among taxa and a succession of scavengers. Macrourids, a dominant abyssal scavenger, either did not respond to the death of their congener or possibly avoided the area. Lack of a response by macrourids may be due to (1) avoidance of sites of dead or dying congeners, (2) high sensitivity to ocean acidification, (3) low nutritional value or weaker odor plumes from carcasses of abyssal versus shallow-water taxa, or (4) rapid departure from sites where a carcass is inaccessible. Camera systems were not deployed in view of carcasses at control sites (away from CO2 pools) during each experiment, and we therefore cannot exclude the possibility that the pattern of scavenger visits was influenced by elevated carbon dioxide levels.

KEY WORDS: Food fall · Behavior · Macrouridae · Coryphaenoides armatus · Zoarcidae · Pachycara bulbiceps · Octopodidae · Benthoctopus sp.

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Cite this article as: Barry JP, Drazen JC (2007) Response of deep-sea scavengers to ocean acidification and the odor from a dead grenadier. Mar Ecol Prog Ser 350:193-207.

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