Abstract:
:Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope. During the austral summer of 2010 ‒ 2011, we used underwater imagery to survey a slope-dwelling population of the lithodid Paralomis birsteini off Marguerite Bay, western Antarctic Peninsula for environmental or trophic impediments to shoreward expansion. The population density averaged ∼ 4.5 individuals × 1,000 m(-2) within a depth range of 1,100 ‒ 1,500 m (overall observed depth range 841-2,266 m). Images of juveniles, discarded molts, and precopulatory behavior, as well as gravid females in a trapping study, suggested a reproductively viable population on the slope. At the time of the survey, there was no thermal barrier to prevent the lithodids from expanding upward and emerging on the outer shelf (400- to 550-m depth); however, near-surface temperatures remained too cold for them to survive in inner-shelf and coastal environments (<200 m). Ambient salinity, composition of the substrate, and the depth distribution of potential predators likewise indicated no barriers to expansion of lithodids onto the outer shelf. Primary food resources for lithodids--echinoderms and mollusks--were abundant on the upper slope (550-800 m) and outer shelf. As sea temperatures continue to rise, lithodids will likely play an increasingly important role in the trophic structure of subtidal communities closer to shore.
journal_name
Proc Natl Acad Sci U S Aauthors
Aronson RB,Smith KE,Vos SC,McClintock JB,Amsler MO,Moksnes PO,Ellis DS,Kaeli J,Singh H,Bailey JW,Schiferl JC,van Woesik R,Martin MA,Steffel BV,Deal ME,Lazarus SM,Havenhand JN,Swalethorp R,Kjellerup S,Thatje Sdoi
10.1073/pnas.1513962112subject
Has Abstractpub_date
2015-10-20 00:00:00pages
12997-3002issue
42eissn
0027-8424issn
1091-6490pii
1513962112journal_volume
112pub_type
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