1. Effects of Hypoxia on Survival and Growth of Barnacle Larvae Off the Oregon Coast
Amanda Amstutz
Department of Zoology
Dr. Bruce Menge
Dafne Eerkes-Medrano

2. HYPOXIA: Dissolved oxygen concentrations of less than 1.4 ml /L
Hypoxia can cause mass die offs of marine life in areas known as DEAD ZONES
I’m interested in die offs of marine species caused by hypoxia and how this effects ecosystems. In the context of our research, hypoxia refers to sea water with low levels of dissolved oxygen, usually of 2.8 mg/L or less. To give you an idea of what 2.8 mg/L represents, sea water of the water you drink from the tap generally has a dissolved oxygen concentration of 5.5 mg/L. Hypoxia is important because oxygen is essential for aerobic metabolism which is common to most forms of life. Hence, when marine organisms are exposed to hypoxia they will often be unable to produce the energy they need to survive which leads to mass die offs of sea critters known as dead zones. Dead zones can have devastating effects on marine ecosystems as well as humans through impacts on fisheries. It’s because of these dead zones that understanding hypoxia is essential to management of marine ecosystems.
Start out with why hypoxia is important, NOT WITH DEFINTTION

3. Hypoxia off the Oregon Coast
Hypoxia in shallow waters
(50m or less) was first documented
in the summer of 2002 and has
occurred every summer from
Off the oregon coast significant dead zones were first seen in the summer of 2002 and have occurred each consecutive summer since with increasing range, severity of hypoxia, and persistence of hypoxia as well of fraction of water column that is hypoxic. These dead zones are baused by hypoxia, specifically near shore, shallow water hypoxia that seems to be the result of changes in wind patterns and water currents off our coast. No one is quite sure. What we are sure of however is the phenomenon of hypoxia so close to shore is not normal. (Graphy). The hypoxia has become severe and consistent enough that the marine community has begun to accept that our oceans have experienced a fundamental change and hypoxia is the new norm. As you can imagine, this has the potential to restructure entire ecosystems, everywhere we see shallow water hypoxia and marine species ill-adapted to such conditions, changes wil occur.

4. Hypoxia off the Oregon Coast
To reinforce this idea visually…
A healthy rockfish reef before 2006 anoxia (left) and after 2006 anoxia (right).

5. Barnacles! Barnacles are found on hard substrata in coastal regions
They are filter feeders
Barnacles have a total of eight life stages
Seven of these life stages are open-ocean larval forms
In order to understand how our oceans are changing, we’ve chose a single organims to measure how hypoxia effects it and that’s the ever charismatic barnacle.

6. Barnacles are important as:
Ecological engineers
Prey
The great thing about barnacles is that although we are directly measuring the effects of hypoxia on the barnacle larvae, any results we find will have much wider implications than simply how hypoxia effects our larvae. Larvae eventually turn into adults of course, so any fluctuations in larvae populations will lead to fluctuations in adult populations. So when we investigate the effects of hypoxia on larvae, ultimately we are trying to understand the effects of hypoxia on adult barnacles. And, because adult barnacles are so important in marine ecosystems, we can use our results to make predictions of how hypoxia will effect entire ecosystems up to salmon and dungesness and of course us.
Photos courtesy Dr. Mark Hixon
Because barnacles are ecologically important species, fluctuations in barnacle populations effect entire ecosystems.

7. Rear barnacle larvae in the laboratory
Research Goals: 1. Determine mortality of larvae at increasingly severe levels of hypoxia for a given exposure period 2. Determine if exposure to hypoxic conditions effects growth of larvae
Expose larvae to hypoxia
Measure survival
(Separate slide for research goals?) Our research goals are to determine mortalilty of barnacle larvae at increasingly severe levels of hypoxia
And two, to determine if exposure to hypoxic conditions effects the growth of the larvae
Monitor growth and development

8. Predictions:
Due to the historical lack of hypoxia close to shore, barnacle larvae are predicted to experience high mortality when exposed to hypoxia
Larvae are predicted to experience increased mortality with increasing severity of hypoxia and duration of exposure
Larvae are predicted to have slower growth rates when they have been exposed to hypoxia
Predicting direct relationship between variables, as to putting numbers to rate, that can’t be done.

9. Preliminary Results
Looking at carbon dioxide, bacteria population composition
Cumulative mortality of Balanus glandula mixed stage larvae through a six day period after exposure to microxia (0.5 mg/l dissolved oxygen) or normoxia (5 mg/L dissolved oxygen) for 24 hours. (Means ±SD; normoxia n=3; microxia n=3 )

10. What’s Next Ensure errors in system have been corrected
Perform 48 and 72 hour trials
Monitor development and growth

11. Acknowledgements Howard Hughes Medical Institute
OSU University Honors College
Dr. Kevin Ahern
Dr. Bruce Menge and Dafne Eerkes-Medrano
Hatfield Marine Science Center
Dr. Chris Langdon