Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8884232 | Deep Sea Research Part I: Oceanographic Research Papers | 2018 | 31 Pages |
Abstract
Benthic octopods cluster on bare rock on Dorado Outcrop, a ~3000â¯m deep basalt exposure. The outcrop hosts intermittent discharge of relatively cool (up to 12.3â¯Â°C) hydrothermal fluid that carries about half as much oxygen as bottom seawater (~54â¯Î¼M vs. 108â¯Î¼M). We analyzed 231â¯h of video footage and still images taken by sub-sea vehicles in 2013 and 2014 that documented the clustered octopods, members of the poorly-known genus Muusoctopus. The largest cluster (102 octopods) occurred in a 19â¯m2 area of fluid discharge, where the basalt was sediment-free; individual octopods were also seen across the outcrop. The clustered octopods appeared to be brooding eggs and a total of 11 egg clutches were confirmed. None of the 186 eggs closely examined showed embryonic development. The intermittent fluid discharge may clear the basalt of sediment and attract gravid octopods which then spawn. However, the increased temperature and limited oxygen of the discharging fluids may threaten the octopods' survival. Octopods in/near areas of discharging fluid had significantly higher estimated respiration rates (3.1-9.8â¯contractions/min) than did octopods away from discharging fluid (0.8-6.0â¯contractions/min). Warm fluids likely increase the octopods' metabolic rate and thus their oxygen demand but provide only limited oxygen. The resultant physiological stress is hypothesized to eventually kill eggs near fluid discharge. We hypothesize, because these eggs do not survive, the population is sustained by a larger pool of undetectable females that brood their eggs inside cool conduits of this and perhaps other, unstudied basalt outcrops.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Anne M. Hartwell, Janet R. Voight, C. Geoffrey Wheat,