title: Recruitment, growth and mortality of an Antarctic hexactinellid sponge, Anoxycalyx joubini.
abstract: Polar ecosystems are sensitive to climate forcing, and we often lack baselines to evaluate changes. Here we report a nearly 50-year study in which a sudden shift in the population dynamics of an ecologically important, structure-forming hexactinellid sponge, Anoxycalyx joubini was observed. This is the largest Antarctic sponge, with individuals growing over two meters tall. In order to investigate life history characteristics of Antarctic marine invertebrates, artificial substrata were deployed at a number of sites in the southern portion of the Ross Sea between 1967 and 1975. Over a 22-year period, no growth or settlement was recorded for A. joubini on these substrata; however, in 2004 and 2010, A. joubini was observed to have settled and grown to large sizes on some but not all artificial substrata. This single settlement and growth event correlates with a region-wide shift in phytoplankton productivity driven by the calving of a massive iceberg. We also report almost complete mortality of large sponges followed over 40 years. Given our warming global climate, similar system-wide changes are expected in the future.
authors: Scripps Institution of Oceanography, La Jolla, California, United States of America. pdayton@ucsd.edu
authors: Paul K
authors: PK
authors: Dayton
authors: Stacy
authors: S
authors: Kim
authors: Shannon C
authors: SC
authors: Jarrell
authors: John S
authors: JS
authors: Oliver
authors: Kamille
authors: K
authors: Hammerstrom
authors: Jennifer L
authors: JL
authors: Fisher
authors: Kevin
authors: K
authors: O'Connor
authors: Julie S
authors: JS
authors: Barber
authors: Gordon
authors: G
authors: Robilliard
authors: James
authors: J
authors: Barry
authors: Andrew R
authors: AR
authors: Thurber
authors: Kathy
authors: K
authors: Conlan
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D018533:Biomass; D005843:Geography; D046448:Ice Cover; D009792:Oceans and Seas; D011161:Porifera / Q000033:anatomy & histology / Q000254:growth & development*; D013997:Time Factors