Hypoxia Updates

Current Updates

August 23, 2012

Recent results from multiple ocean observing platforms indicate that moderate to severe hypoxia is occurring along parts of the central Oregon shelf. The MI_LOCO/PISCO bottom  lander at 70m (38 fathom) depth off Cape Perpetua has recorded severe hypoxia (DO < 0.5 ml/l) since August 12th with DO levels dropping as low as ca. 0.1 ml/l.  These are among the lowest values that we have measured over the past decade.  When upwelling-favorable winds have been strong, this offshore near-bottom hypoxic water has been transported into the inner shelf (water depths less than 50 m = 27 fathoms).  A shallow-water (15 m = 8 fathoms) PISCO mooring at Cape Perpetua has recorded similarly low (<0.5 ml/l) oxygen values during the recent period of strong upwelling-favorable winds.  As in past years, the most intense hypoxia appears to be centered south of Newport.  Glider data from the NH-line off Newport from Aug 3-8 and 18-20 indicate that hypoxic (dissolved oxygen < 1.43 ml/l) though not severely hypoxic (<0.5 ml/l) water extends across the shelf and extends up to 20 m above the bottom.  An inner-shelf (15 m = 8 fathoms) PISCO mooring located off Lincoln Beach also shows hypoxia but not severe hypoxia.

Based on the weather forecast, we expect hypoxic conditions to persist or worsen over the next week.  Conditions conducive to further hypoxia are likely to persist until strong low pressure systems reverse the regional winds which typically occurs in late September to early October. While we are working to make additional observations, we wanted to share these results with you in a timely manner.

Though there is the potential for this hypoxic event to impact fisheries, there is not enough data yet to know which areas or species will be affected.  If you or anyone you know would like to report unusual fish behavior or changes in catch in pots or traps, please send an email to hypoxia@science.oregonstate.edu. We will be sending out updated information as we collect and analyze more data.

UPDATES FROM last year

August 19, 2011

PISCO researchers Jack Barth and Francis Chan are reporting low dissolved oxygen (DO) concentrations off the central coast of Oregon from roughly Seal Rock to Cape Perpetua.  Data from an OSU bottom lander (70m depth) show DO concentrations decreasing in that region during the first two weeks of August and reaching  0.5 ml/l (milliliters per liter of seawater) on August 13th.  Data from PISCO cruises on August 18th confirm the low values in this Seal Rock toCape Perpetua region. Data from the Newport area show higher concentrations of DO.

ODFW biologists Mike Donnellan and Bill Miller recently surveyed deep (~40-45 m) reefs offshore of Cape Perpetua and Lincoln City with a Remotely Operated Vehicle.  From August 8-10, they observed healthy, active fish communities (e.g., black , canary, quillback, and copper rockfishes) at the Cape Perpetua and Lincoln City sites  when near-bottom DO stood at 0.9 ml/l and 1.6 ml/l, respectively.  How the more recent drops in DO have affected fish and invertebrates is unclear but past DO declines to 0.5 ml/l were associated with fish mortality and movement away from reef habitats.  ODFW biologists are monitoring for changes to nearshore fishery patterns that have signaled the onset of oxygen stress in previous years, such as increased movement of Dungeness crabs into estuaries, and changes in the location and composition of nearshore groundfish catches.  Some of these signs have been observed recently, but are thus far within the normal range of variability for this time of year.

Though there is the potential for this hypoxic event to impact fisheries, there is not enough data yet to know which areas or species will be affected.  If you or anyone you know would like to report unusual fish behavior or changes in catch in pots or traps, please send an e-mail to hypoxia@science.oregonstate.edu.  We will be sending out updated information as we collect and analyze more data. 

 June 27, 2011

Researchers from the Northwest Fisheries Science Center (at HMSC in Newport, OR) report that they are already seeing fairly low oxygen values in June (1.40 ml/L at NH05 on 22 June at 56 m depth = hypoxic) yet upwelling has been very weak this spring (based on the PFEL upwelling index).  Local winds have been weak as well although they were blowing pretty strong on June 24th.   There has been a huge bloom the past week or two so maybe it has already begun to sink to the bottom and began to decompose.  In addition, copepod biomass is twice as high this spring as any other spring in the past 16 years thus maybe the rain of pellets to the sea floor and subsequent decomposition has drawn the oxygen down to hypoxic levels.

June 24, 2011

Recent observations from PISCO profiles off Cape Perpetua and the NH10 mooring off Newport show dissolved oxygen levels to be hovering around 1.5 ml/L at 36.5 fathoms (73 meters).  These values are expected for this time of year and are the result of upwelling caused by persistent winds from the north.  For clarity, the shelf is not described as hypoxic until dissolved oxygen levels reach 1.4ml/L.  

Researchers continue to monitor the status of the coastal ocean off Oregon's central coast.  Depending on the rate of primary production, bacterial respiration and prevailing currents, it is possible that the system could experience severe hypoxia (defined as 0.5ml/L), though it could still take weeks or months for that to occur (if at all).

30-day data from the NH10 mooring can be viewed here: NH10 Mooring Data

June 8, 2011

ODFW attempted to conduct their pre-season sampling on 5/31-6/1, but were shut out due to very poor underwater visibility on the seafloor.  However, the limited video footage that was obtained at Cape Perpetua was indicative of non-hypoxic conditions (e.g., plentiful, active fish, healthy-looking epibenthic macroinvertebrates).  Video review and analysis of ROV footage dating to 2000 is ongoing, with results and a report planned for later this year.  An analysis of fisheries performance versus hypoxia is also planned for later this year.

ODFW's acoustic telemetry moorings that were deployed at Cape Perpetua in 2010 to research rockfish movements and home range is complete, and will not be re-deployed in 2011.

For more information please send an email to hypoxia@science.oregonstate.edu

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