A Tidal Driven Life Ep. 1: The Study Begins

Field site at Netarts Bay, OR

I arrived in Oregon in June, of 2016, having never eaten an oyster, let alone studied them. Since then I’ve learned about their life cycle, importance to the environment, their service as a harvestable resource and have developed the unnatural ability to know the phase of the moon and the times of the low tides. It has been a little over a year since the oysters I’ve been cultivating in Netarts Bay were initially deployed and so it’s time to write a blog post.

Securing oyster bags on top of shell plantings. Photo credit: Tiffany Woods, Oregon Sea Grant

The growth has been more physical than mental for the oysters. They’ve gone from a few millimeters to an average of over 5 cm in length. My growth, on the other hand, has been much more mental. I’ve had the opportunity to work with and learn from some incredible people in the College of Earth, Ocean, and Atmospheric Sciences, here at Oregon State University. I’ve been extremely lucky to work with my advisor Dr. Alyssa Shiel, as well as Drs. George Waldbusser and Adam Kent on this research funded by Oregon Sea Grant. I’ve also had the opportunity to work with an amazing set of graduate students and who’ve taught me so much in the past year.

So what have I been doing over the past year and why? Read more next week when this series continues!

A Tidal Driven Life Ep. 2: What’s the Idea?

Project Overview:

Six oyster plots on the mudflat in Netarts Bay. Photo credit: Tiffany Woods, Oregon Sea Grant

In August of 2016, some incredible volunteers and I set up 6 oyster plots in the mudflats of Netarts Bay, just in front of Whiskey Creek Shellfish Hatchery in Tillamook, Oregon. Since then I’ve been back on a fortnightly schedule to check on my oysters and stain them for an hour with two dyes designed to mark growth in their shells. The two dyes I use are calcein (fluorescent), and a manganese spike (remember these! We’ll get to them later). On a quarterly schedule, I’ve also been collecting some of these oysters to bring back to the lab at OSU for analysis.

Graduate student Beth Rutila pounding rebar poles into the mudflats of Netarts Bay during construction of the 6 oyster plots.

Successful initial deployment of oyster bags into Netarts Bay. Photo credit: Alyssa Shiel

Why have I been doing this? My goals are two-fold:

  1. To develop a pH (CO32-) proxy using uranium and calcium ratios (U/Ca) in oyster shells
  2. To determine if implementing shell plantings for growing oyster shells could be used to reduce the effects of ocean acidification.

You may be asking yourself, what are shell plantings? Good question! Simply put they’re bags of dead oyster shells that have been placed beneath live, growing oyster shells. See the picture below to see what it looks like! Why are we doing this? Keep reading next week to find out!

The leaning black bag contains live oysters, the bags below this are the shell plantings! Photo credit: Tiffany Woods, Oregon Sea Grant

A Tidal Driven Life Ep. 3: Why does it matter?

The Why:

Dr. George Waldbusser re-attaching predator a bag filled with oysters. Photo credit: Gustavo Garcia, Oregon Sea Grant.

Oysters provide critical ecosystem services including providing habitat, locally buffering against corrosive conditions, and serving as a harvestable resource. In addition, coastal economies including the livelihoods of hatchery personnel and oyster growers depend on healthy oyster populations.

Rising atmospheric carbon dioxide levels have resulted in acidification of the Earth’s oceans. With CO2 levels expected to continue to rise, great concern exists over the impact ocean acidification will have on marine ecosystems. In coastal regions such as the Pacific Northwest upwelling may contribute to regional ocean acidification by bringing low pH water to the surface. This low pH water is corrosive to calcium carbonate shells such as those formed by bivalves (like oysters), crustaceans and corals.

Water chemistry sensors are extremely expensive to implement, meaning that only a select few estuaries have pH and carbonate system chemistry resolved. Using our pH proxy will allow us to understand the variability of pH (CO32-) within Netarts Bay. The successful development of this proxy will allow us to use oyster shells as a means of resolving water chemistry in areas where water chemistry instruments are cost prohibitive.

Paraphrasing the words of Dr. George Waldbusser, dissolution of these dead oyster shells act as the Alka-Seltzer of the sea, buffering the local water around the living oysters situated on top of the shell plantings. Shell planting is a potential tool for buffering against increasingly acidic oceans as well as local acidity associated with remineralization of organic matter and the associated production of carbon dioxide at the sediment-water interface.

Next week: how do we take these concepts and apply it in research?

Oysters being stained at Whiskey Creek Shellfish Hatchery. Photo credit: Anna Miller

A Tidal Driven Life Ep. 4: How do we do this work?

The How:

Once I have the samples back in the lab, I measure, dry, and weigh each part of the oyster (the top shell, meat, and bottom shell). Then comes the fun part. I use a small Dremel saw to cut the bottom shell in half along the hinge. This is when that calcein dye comes into play. When we stain the oysters with calcein, we are essentially making a date mark as the fluorescent dye is incorporated into their shells (see the image below). Think of this like looking at tree rings! We can take pictures of this stain, which allows us to determine the growth rate between each period of staining.

The hinge of an oyster showing lines of fluorescent calcein staining. Each defined green line represents a date and time when the oyster was immersed in the calcein stain.

Once I have finished imaging the oysters, I can analyze them for their U/Ca ratios. I do so using a laser ablation inductively coupled mass spectrometer (LA-ICP-MS). This machine allows us to trace a path along the line of growth on the hinge of the oyster to analyze the chemical makeup of the shell. At my sample site, we are lucky to have such an instrument in place very close to the location of our oysters. Thus providing us a means of calibrating our U/Ca proxy.

Next week will wrap up this series with a discussion of next steps and the fabulous people who make this work possible.

A Tidal Driven Life Ep. 5: A look into the future

Photo credit: Kali Melby

 Where we go from here:

If results show that the shell plantings improve the health of the oyster populations, oyster fishermen may implement them as an adaptation strategy to mitigate the effect of ocean acidification.

Development of the pH proxy will support future scientific efforts to evaluate variability in oyster experiences over large areas and over time as pH continues to increase in response to higher atmospheric CO2 levels.

The Crew:

I’d like to thank Whiskey Creek Shellfish Hatchery for allowing me to do my field work on site, and for their support of my work.

Collin Ruark and Peter Chace cleaning predator bags.

Additionally, I cannot talk about my research without adding an enormous thank you to all of the people who have helped me in the past year. My fieldwork is a minimum of a three-person job, and as a result, I’ve needed to plead for volunteers to help me. Luckily, I have some incredible friends who have jumped at my call.

REU students Brooke Mattson and Anna Miller sampling in July 2017.

They’ve been enthusiastic, flexible, patient, and all around incredible. They’ve stuck with me through foggy night-time sampling when we could barely find the sample plots, downpours, 5:00 AM starts, 2:00 AM ends, crab infestations, and surprise elk encounters. Secretly I think they do it for the tacos.

Graduate students taking part in the traditional taco truck feast before sampling.

Want to see and learn more? Check out this video from Oregon Sea Grant!