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- Black pools of death: Hypoxic, brine-filled ice gouge depressions become lethal traps for benthic organisms in a shallow Arctic embayment,
- Numerous small (9 ± 7 m2, mean ± SD) depressions filled with dark water were found covering 14% of the shallows (<10 m) sea floor of Resolute Bay, NWT, Canada, on July 28, 1995. The water in these black pools was hypoxic, warmer, and more saline and sulfide rich than surrounding bottom water. These pools also contained high numbers of dead epibenthic species, including: shrimps, amphipods, mysids, bivalves, gastropods, sea cucumbers, and fishes. Infaunal abundance and biomass, as well as benthic chlorophyll concentrations, were significantly lower inside the black pools than in the surrounding sediments. The pools persisted until the first strong wind to occur after annual sea-ice break-up. A year (July 1996), sulfide-rich black saline pools were again found in the same depressions as well as in new depressions formed by grounding ice during the previous summer. We hypothesize that the pools form annually, as the sea ice expels dense brine, which sinks and collects in previously formed ice gouge depressions on the shallow of Resolute Bay. Benthic respiration would be sufficient to drive the stratified water in the pools to anoxia in the absence of currents and turnover, resulting in microbial production of highly toxic sulfides. Once established, the pools persist as lethal traps for benthic and demersal organisms until dispersed by wind or waves after breakup of the annual ice cover., Cited By (since 1996):27, Invertebrates, CODEN: MESED, ,
- Kvitek, Conlan, Iampietro
- Recolonization of soft-sediment ice scours on an exposed Arctic coast,
- Ice scour is the most disruptive and widespread physical disturbance that naturally affects the coastal benthos in polar waters, where it creates a mosaic of disturbances in various stages of recolonization. The purpose of this study was to (1) determine the timing and sequence of biotic recovery following ice scour disturbance of soft sediment and (2) test the general hypothesis that ice scour increases biotic diversity in high-latitude benthic communities. The study area was a 6.6 km length of Barrow Strait along the exposed coast of Cornwallis Island in High Arctic Canada. Core-collected (0.0075 m2) macrofauna (≥0.5 mm) inhabiting 19 scours at 12 to 28 m depth were sampled during open water in August of 1991 to 1996 and again in 1999. We repeat-sampled 2 scours for 6 summers, 3 scours for 3 summers, and 2 for 2 summers, while the other 12 scours were sampled once. Sampling was severely limited by availability of open water which was constrained by frequent invasion of the study area by drift ice. Young ice scours were refugia for the dorvilleid polychaete Ophryotrocha spatula. Its numbers declined precipitously as the scours aged. Other early colonists maintained or increased their abundance. Most of the later colonists significantly increased in abundance as the scours aged despite the presence of the early colonists. Abundance, biomass and species richness increased progressively with scour ageing but did not significantly exceed that in the unscoured community. Thus, although the scours differed from the unscoured reference community in species composition, they were not havens for species-rich or highly different assemblages (at least not among core-collected macrofauna). Recolonization of ice scours ≤9 yr old fitted a linear model. Assuming that further colonization would continue to be linear, the 2 scours monitored the longest had achieved 65 to 84% recolonization by Ages 8 to 9. The unscoured reference community was significantly more diverse, massive and abundant where disturbance was a chronic but infrequent occurrence, compared to where it was protected from ice scour by an offshore rise. Thus, ice scour appears to have a positive effect on the benthos of this coast. © Inter-Research 2005., Cited By (since 1996):36, CODEN: MESED, , , Downloaded from: http://www.int-res.com/abstracts/meps/v286/p21-42/ (13 June 14).
- Conlan, Kvitek