title: No barrier to emergence of bathyal king crabs on the Antarctic shelf.
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.
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901; raronson@fit.edu.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Aronson
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Smith
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Vos
authors.affiliation: Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294;
authors.forename: James B
authors.initials: JB
authors.lastname: McClintock
authors.affiliation: Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294;
authors.forename: Margaret O
authors.initials: MO
authors.lastname: Amsler
authors.affiliation: Department of Marine Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden;
authors.forename: Per-Olav
authors.initials: PO
authors.lastname: Moksnes
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Ellis
authors.affiliation: Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kaeli
authors.affiliation: Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
authors.forename: Hanumant
authors.initials: H
authors.lastname: Singh
authors.affiliation: Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
authors.forename: John W
authors.initials: JW
authors.lastname: Bailey
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Schiferl
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Robert
authors.initials: R
authors.lastname: van Woesik
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Michael A
authors.initials: MA
authors.lastname: Martin
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Brittan V
authors.initials: BV
authors.lastname: Steffel
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Deal
authors.affiliation: Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901;
authors.forename: Steven M
authors.initials: SM
authors.lastname: Lazarus
authors.affiliation: Department of Marine Sciences-Tjärnö, University of Gothenburg, SE-452 96 Strömstad, Sweden;
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Havenhand
authors.affiliation: Department of Marine Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden; Section for Oceanography and Climate, National Institute of Aquatic Resources (DTU Aqua), Technical University of Denmark, DK-2920 Charlottenlund, Denmark;
authors.forename: Rasmus
authors.initials: R
authors.lastname: Swalethorp
authors.affiliation: Department of Marine Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden; Section for Oceanography and Climate, National Institute of Aquatic Resources (DTU Aqua), Technical University of Denmark, DK-2920 Charlottenlund, Denmark;
authors.forename: Sanne
authors.initials: S
authors.lastname: Kjellerup
authors.affiliation: Ocean and Earth Science, University of Southampton, Southampton SO14 3ZH, United Kingdom.
authors.forename: Sven
authors.initials: S
authors.lastname: Thatje
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D057231:Climate Change; D003445:Crustacea / Q000502:physiology*; D005260:Female; D008297:Male; D011157:Population Dynamics; D012726:Sexual Behavior, Animal
keywords: Southern Ocean; biological invasion; climate change; polar emergence; predation