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- Recruitment, Growth and Mortality of an Antarctic Hexactinellid Sponge, Anoxycalyx joubini
- 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. © 2013 Dayton et al., Cited By (since 1996):4, Art. No.: e56939, Downloaded from: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0056939 (16 June 2014).
- Dayton, Kim, Jarrell, Oliver, Hammerstrom, Fisher, O'Connor, Barber, Robilliard, Barry, Thurber, Conlan
- Swarming benthic crustaceans in the Bering and Chukchi seas and their relation to geographic patterns in gray whale feeding,
- Swarms differed in their geographic extent, local biomass, and life stages of swarming individuals and thus in their availability to feeding Eschrichtius robustus. Immature amphipods apparently swarmed for dispersal, whereas cumaceans probably swarmed for mating. All life stages of the hyperbenthic mysids occurred above the sea floor. Although the geographic spread of mysid swarms and shrimp communities was much greater than for the amphipod and cumacean swarms, the latter swarmed in denser patches to produce higher local biomass. Crustacean swarms are important in describing the geographic patterns of gray whale feeding from the Chukchi Sea to Baja California. The primary feeding ground is in the S Chukchi Sea and especially the N Bering Sea, where gray whales suck infaunal amphipods from fine sand. The primary feeding ground is divided into a relatively deep zone (>20 m), where tube-dwelling ampeliscid amphipods are the major prey, and a shallow zone (<20 m), where burrowing pontoporeid amphipods dominate. The secondary feeding ground is in the S Bering Sea along the E Alaska Peninsula and adjacent Alaskan mainland where shrimp and mysids are the major prey. -from Authors, Cited By (since 1996):16, Invertebrates, Marine Mammals, Birds & Turtles, ,
- Kim, Oliver