ScholarWorks@UA

Assessment of the benthic environment following offshore placer gold mining in Norton Sound, northeastern Bering Sea

DSpace/Manakin Repository

Show simple item record

dc.contributor.author Jewett, Stephen Carl
dc.date.accessioned 2018-08-08T19:03:21Z
dc.date.available 2018-08-08T19:03:21Z
dc.date.issued 1997
dc.identifier.uri http://hdl.handle.net/11122/9482
dc.description Thesis (Ph.D.) University of Alaska Fairbanks, 1997
dc.description.abstract The effects of placer gold mining on the benthic environment of Norton Sound in the northeastern Bering Sea were assessed. Research focused on red king crab Paralithodes camtschaticus, a species with commercial and subsistence importance in the Sound and seasonal occurrence in the mining area. The study addressed mining effects on: (1) benthic macroinvertebrates, many serving as food for this crab, (2) crab relative abundance, distribution, and food, and (3) heavy metal concentrations in crabs. Mining on variable substrates in $<$20 m water depths occurred between 1986-90 during ice-free months when crabs were further offshore. Sampling nearly a year subsequent to mining revealed moderate substrate alteration. Benthic community parameters and abundance of numerically predominant families (e.g., owenid, spionid, and capitellid polychaetes and echinarachniid sand dollars) were reduced in mined areas. Many reduced taxa are known crab prey. Although young individuals of opportunistic taxa predominated, taxa were generally smaller at mined areas. Multi-year surveys of a once-mined area showed continued smoothing of bottom relief. Ordination of taxon abundance from mined (1 yr after mining), recolonizing (2-7 yrs after mining), and unmined stations reflected decreasing station disturbance. At least four years were required for benthos to recover from mining. Mining had a negligible effect on crabs. Crab catches, size, sex, and most prey groups in stomachs were similar between mined and unmined areas. Concentrations of eight heavy metals in muscle and hepatopancreas tissues were generally not different in mined areas. Furthermore, these metals were not different in sediments upcurrent and downcurrent of mining. Concentrations of most metals in tissues showed no temporal trend. Elemental concentrations in muscle tissues were below or within the range of concentrations in red king crabs from other North Pacific locations. Most metals from Norton Sound crabs were well below federal guidance levels for human consumption. Effects from mining were apparent for benthic macrofauna with virtually no effects observed for king crabs. Absence of any demonstrable effects of mining on this crab is primarily a result of the high natural dynamics of the Sound and opportunistic feeding behavior and high mobility of the crab.
dc.subject Environmental engineering
dc.subject Mining engineering
dc.subject Environmental science
dc.subject Biological oceanography
dc.title Assessment of the benthic environment following offshore placer gold mining in Norton Sound, northeastern Bering Sea
dc.type Thesis
dc.type.degree phd
dc.identifier.department Division of Fisheries
dc.contributor.chair Smith, Ronald L.


Files in this item

This item appears in the following Collection(s)

Show simple item record

Search ScholarWorks@UA


Advanced Search

Browse

My Account

Statistics