Upwelling-driven nearshore hypoxia signals ecosystem and oceanographic changes in the northeast Pacific.
Seasonal development of dissolved-oxygen deficits (hypoxia) represents an acute system-level perturbation to ecological dynamics and fishery sustainability in coastal ecosystems around the globe. Whereas anthropogenic nutrient loading has increased the frequency and severity of hypoxia in estuaries and semi-enclosed seas, the occurrence of hypoxia in open-coast upwelling systems reflects ocean conditions that control the delivery of oxygen-poor and nutrient-rich deep water onto continental shelves. Upwelling systems support a large proportion of the world's fisheries, therefore understanding the links between changes in ocean climate, upwelling-driven hypoxia and ecological perturbations is critical. Here we report on the unprecedented development of severe inner-shelf (<70 m) hypoxia and resultant mass die-offs of fish and invertebrates within the California Current System. In 2002, cross-shelf transects revealed the development of abnormally low dissolved-oxygen levels as a response to anomalously strong flow of subarctic water into the California Current System. Our findings highlight the sensitivity of inner-shelf ecosystems to variation in ocean conditions, and the potential impacts of climate change on marine communities.
Grantham
Brian A
BA
Washington State Department of Ecology, Coastal and Estuarine Assessment Unit, Olympia, Washington 98504, USA.
Chan
Francis
F
Nielsen
Karina J
KJ
Fox
David S
DS
Barth
John A
JA
Huyer
Adriana
A
Lubchenco
Jane
J
Menge
Bruce A
BA
D000818:Animals; D002140:California; D002980:Climate; D017753:Ecosystem; D005398:Fisheries; D005399:Fishes / Q000502:physiology*; D007448:Invertebrates / Q000502:physiology*; D009791:Oceanography; D009922:Oregon; D010100:Oxygen / Q000032:analysis*; D010140:Pacific Ocean; D011157:Population Dynamics; D012621:Seasons; D012623:Seawater / Q000737:chemistry*; D013997:Time Factors; D014872:Water Movements
D010100:Oxygen