(1 - 2 of 2)
- Seastar response to organic enrichment in an oligotrophic polar habitat,
- The high Antarctic marine system, including McMurdo Sound, is food limited. Benthic scavengers, especially the seastar Odontaster validus, respond rapidly to sources of organic material, however, fecal material from the McMurdo Station sewage outfall is not consumed. Laboratory and field experiments showed that O. validus responded quickly (within hours) to organically enriched sediments, but that the presence of the anaerobic bacteria Beggiatoa spp. modified seastar behavior. In the lab, anoxic sediments, even more strongly than the presence of Beggiatoa, caused seastar avoidance. In the field, Beggiatoa caused seastar avoidance even of organically enriched sediments. The large mass of organic material remaining from pre-sewage treatment years at the McMurdo outfall is currently completely covered by a thick Beggiatoa microbial mat. O. validus and other megafaunal scavengers are abundant nearby but do not feed on the sewage organics that are covered by the microbes. The outfall deposit is thus likely to exist for a long period of time, undergoing slow anaerobic microbial degradation rather than rapid processing by megafaunal scavengers. This is an example of competition between constituents of the microbial and megafaunal communities and espouses the need for an ecosystem approach to ecology rather than community analysis within a limited size class (i.e. mega-, macro-, meio-, or micro-fauna). © 2007 Elsevier B.V. All rights reserved., Cited By (since 1996):10, Invertebrates, CODEN: JEMBA, ,
- Kim, Thurber, Hammerstrom, Conlan
- 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