Effects of Oil and Chemically Treated Oil on Nearshore Under-Ice Meiofauna Studied <i>in Situ</i>
DOI:
https://doi.org/10.14430/arctic1819Keywords:
Algae, Animal distribution, Animal population, Canada. Baffin Island Oil Spill Project, Copepoda, Environmental impacts, Marine oil spills, Microbial ecology, Nematoda, Polychaeta, Sea ice ecology, Byron Bay, Labrador, Hatt, Cape, waters, Nunavut, Ragged ChannelAbstract
Meiofauna collected during May 1982 in the soft bottom layer of nearshore landfast ice at Cape Hatt, northern Baffin Island, were dominated by cyclopoid copepods, harpacticoid copepods, nematodes and polychaete larvae (73.5, 15.4, 6.3 and 3.5% of total numbers respectively). Also included were rotifers, gastropod veligers and calanoid copepod nauplii; calanoid nauplii were probably present in the near-ice water and not on or in the ice. Average abundance of all ice meiofauna was 54,000 individuals/sq m. Densities of all meiofauna groups were spatially variable, but only nematodes and cyclopoid copepods showed evidence of progressive temporal change between 18 May and 2 June. Undisturbed, enclosed areas of the under-ice surface were treated with oil on 23-24 May. Dispersed oil (Venezuela Lagomedio + Corexit 9527, BP CTD or BP 1100 WD) was in contact with the ice for 5 hours, whereas untreated oil and solidified oil (BP treatment) remained in the enclosures for the duration of the study (12 days post-treatment). Sampling was carried out in areas where oil contacted the ice and moved away or in areas near oil that remained in contact with the under-ice surface. Five hours after treatment, oil concentrations in the water within the enclosures were similar (0.15-0.28 ppm) in untreated oil, solidified oil and control enclosures. In contrast, dispersed oil oil concentrations were 5.8-36.5 ppm. Densities of all copepods and polychaetes decreased dramatically in each dispersed oil enclosure by the second post-spill day, and slight density increases were evident by the tenth post-spill day. Harpacticoid copepods apparently were more sensitive to dispersed oil than were cyclopoid copepods. Densities of nematodes and cyclopoid copepod nauplii were not affected by dispersed oil. Densities of nematodes, polychaetes and all copepods were not affected by untreated or solidified oil, but there was some evidence of a stimulatory effect of those treatments on some copepod groups and life stages.
Key words: Arctic, ice meiofauna, ice copepods, ice polychaetes, ice nematodes, oil effects, dispersed oil effects, solidified oil effects, Baffin Island
