Publications

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2007
Blankenship, LE, Levin LA.  2007.  Extreme food webs: Foraging strategies and diets of scavenging amphipods from the ocean's deepest 5 kilometers. Limnology and Oceanography. 52:1685-1697.   10.4319/lo.2007.52.4.1685   AbstractWebsite

We explore hypotheses that alternate foraging strategies, diet, or nutrient partitioning could help explain the success of scavenging Lysianassoids (Amphipoda) in hadal oligotrophic trenches (depths of 6-11 km) by examining the nutritional strategies of four lysianassoid species ( Eurythenes gryllus, Scopelocheirus schellenbergi, Hirondellea dubia, and Uristes sp. nov.) collected with baited traps (6.3-10.8 km) from the oligotrophic Tonga and Kermadec Trenches (southwest Pacific Ocean). Diets and foraging strategies were examined by use of (1) the nascent DNA-based analysis of hindgut contents, which provides a 'snapshot' of recently ingested organisms, and (2) natural abundance isotopic signatures, which reflect the source of nutrition and relative trophic position. The scavenging guild exhibits remarkable trophic plasticity, and each amphipod species employs alternate foraging modes, including detrivory or predation, to supplement necrophagy. The nutritional strategies of some species appear to shift with age, depth, and even between trenches. Thus, there is no single ubiquitous hadal food web; rather it is influenced by depth and overlying surface productivity. Isotopic data suggest that coexisting species partition the dietary items, providing evidence of competition among members of the scavenging guild. The extreme foraging flexibility of scavenging amphipods may ultimately contribute to their success in severely food-limited hadal ecosystems.

2006
Blankenship, LE, Yayanos AA, Cadien DB, Levin LA.  2006.  Vertical zonation patterns of scavenging amphipods from the Hadal zone of the Tonga and Kermadec Trenches. Deep-Sea Research Part I-Oceanographic Research Papers. 53:48-61.   10.1016/j.dsr.2005.09.006   AbstractWebsite

Deep-sea trenches present an ideal system in which to study vertical zonation, though the difficulties inherent in studying these great depths have thus far deterred such research. Here, we present the first account of the structure and vertical zonation of the scavenging guild residing in the hadal habitat of the Tonga and Kermadec Trenches (SW Pacific Ocean). Four species of scavenging amphipod (Eurythenes gryllus, Scopelocheirus schellenbergi, Hirondellea dubia, and Uristes sp. nov.) were captured with baited free-vehicle traps set 1 m above the seafloor and deployed to bottom depths between 5155 and 10,787 m. Each species occupied a distinct vertical zone of 3.5 km or less, and the scavenging amphipod assemblage vertically partitioned the hadal zone. Scavenging amphipod diversity and evenness sharply declined below 9 km. For S. schellenbergi and H. dubia, population structure was stratified ontogenetically. Early instars appeared to reside exclusively in the shallower depths of each species' vertical zone, and were functionally missing from the median and deeper regions. We captured brooding Uristes sp. nov. females, documenting the first bait-attendance event of brooding amphipods in the hadal zone. Separation of habitat in conjunction with deviations in reproductive traits, behaviors, and nutritional strategies may facilitate the coexistence of these four related species in this harsh and confining habitat. (c) 2005 Elsevier Ltd. All rights reserved.