Baited landers were deployed at 83 stations at four locations in the west Pacific Ocean from bathyal to hadal depths: The Kermadec Trench, the New Hebrides Trench, the adjoining South Fiji Basin and the Mariana Trench. Forty-seven putative fish species were observed. Distinct fish faunal groups were identified based on maximum numbers and percentage of observations. Both analyses broadly agreed on the community structure: A bathyal group at <3000. m in the New Hebrides and Kermadec trenches, an abyssal group (3039 - 4692. m) in the Kermadec Trench, an abyssal-hadal transition zone (AHTZ) group (Kermadec: 4707-6068. m, Mariana: 4506-6198. m, New Hebrides: 2578-6898. m, South Fiji Basin: 4074-4101. m), and a hadal group of endemic snailfish in the Kermadec and Mariana trenches (6750-7669. m and 6831-8143. m respectively). The abyssal and hadal groups were absent from the New Hebrides Trench. Depth was the single factor that best explained the biological variation between samples (16%), the addition of temperature and average surface primary production for the previous year increased this to 36% of variation.The absence of the abyssal group from the New Hebrides Trench and South Fiji Basin was due to the absence of macrourids (Coryphaenoides spp.), which defined the group. The macrourids may be energetically limited in these areas. In their absence the species of the AHTZ group appear released of competition with the macrourids and are found far shallower at these sites.The fish groups had distinct feeding strategies while attending the bait: The bathyal and abyssal groups were almost exclusively necrophagous, the AHTZ group comprised predatory and generalist feeders, while the hadal snailfishes were exclusively predators. With increasing depth, predation was found to increase while scavenging decreased. The data suggest scavenging fish fauna do not extend deeper than the hadal boundary.
|Number of pages||16|
|Journal||Deep Sea Research Part I: Oceanographic Research Papers|
|Early online date||21 Dec 2016|
|Publication status||Published - 1 Mar 2017|
This work was funded by the TOTAL Foundation (France) through the projects ‘Multi-disciplinary investigations of the deepest scavengers on Earth’ (2010–2012) and ‘Trench Connection’ (2013–2015) awarded to A.J.J. The 2014 field work was funded by the HADES-K and HADES-M projects supported by the National Science Foundation (NSF) and the Schmidt Ocean Institute (SOI) respectively. We thank the crew and company of the RV Kaharoa (KAH1109, KAH1202, KAH1301 and KAH1310), and NIWA Vessels Management, New Zealand. We also thank the crew and company of the RV Thomas G. Thompson (TN309; HADES-K) and the RV Falkor (FK141109; HADES-M). T.D.L. and A.J.J. are supported by the Marine Alliance for Science and Technology for Scotland (MASTS) pooling initiative, whose support is gratefully acknowledged. P.J.M. and M.R.C. participated in the study through the New Zealand Foundation for Research, Science and Technology (now Ministry for Business, Innovation and Education) funded project ‘Impact of Resource Use on Vulnerable Deep-Sea Communities’ (CO1X0906). J.C.D and M.E.G. were supported by NSF (OCE-1130712) and M.E.G was also funded by the NSF Graduate Research Fellowships Program, both of whose support is gratefully acknowledged. ALS contribution was supported (in part) by the NZ Ministry of Research and Innovation through Te Papa subcontract within NIWA’s Biodiversity and Biosecurity Science Programme (previously NIWA’s FoRST contract C01X0502). Thanks are extended to Dr Kenneth J. Sulak of the U.S. Geological Survey and Dr Jørgen Nielsen of the Natural History Museum of Denmark for discussion on the identification of the synaphobranchid eels and Bassozetus spp. respectively. Thanks also to Matteo Ichino of the National Oceanographic Centre who assisted with the benthic POC estimates and Heather Stewart of the British Geological Survey who categorised the sediment types seen in the lander images.
- Abyssal hadal transition zone
- Deep sea
- Deep-sea fish
- Kermadec Trench
- Mariana Trench
- New Hebrides Trench
- Pacific Ocean
- South Fiji Basin