Oyster Boy Meets Oyster Girl

It's Valentine's weekend and there's no better time to have THE TALK: how do boy oysters and girl oysters make baby oysters?

First, you have to embrace the transgender nature of oysters. Scientists disagree on the specifics, but they do agree that some oysters change gender during their life. Some researchers say that oysters change several times in their lifespans, some say they switch just once. Some say that they change only in response to an overabundance of oysters of the same sex; others say it's just the ladies who change; and some say that all oysters are born male, and as they get older, change to females (the ultimate cougar). Regardless, there are boy oysters and girl oysters. And you can't tell them apart just by looking at them, says Dr. Ami Wilbur, director of the UNCW Shellfish Hatchery in Wilmington, NC.

Dr. Ami Wilbur, director of the UNCW Shellfish Hatchery,
shows off the oysters she's mating.

Dr. Wilbur should know. She is leading the effort to cross breed Virginia and North Carolina oysters to develop several varieties of fast-growing, certified disease tolerant, restaurant-quality oysters to grow off the North Carolina coast.

So how do you make an oyster mate? (With restraint. They're all so "shellfish.") It starts with a rousing game of shell monty and ends with oyster IVF. Without being able to tell if an oyster is male or female from the outside, the researchers have to open an oyster's shell and examine them under a microscope to look for eggs or sperm. (Privacy, please.) In some seasons, one gender may significantly outnumber another, leaving the researchers in a haste to find a mate, says Wilbur.

Once the team - because it takes a team - finally finds a male and a female, it begins a process called "strip spawning." The ladies have up to 100 million eggs (really, who's counting?) because in the wild she releases her eggs in the open waters. It's a crapshoot whether the eggs find a sperm. In the lab, the eggs and sperm are mixed and watched as they develop into larvae then veliger then to oyster spat. Spat finally become oysters when they reach 25mm, or when Dr. Wilbur says they are ready.

From egg/sperm to larvae to veliger to spat … all in a few weeks.
Designed by Melissa Mitchell, a former volunteer with the
Oyster Spat Monitoring Project at UNCW.

At the UNCW research facility, the spat are carefully marked, fed homegrown algae, and measured often. Some spat are sent to three oyster farms along the North Carolina coast to see how they grow in different waters. Based on the results from the lab and the farms, the best oysters are cross bred again and again in an effort to ultimately develop six to eight varieties of North Carolina oysters.

Each oyster is carefully numbered in the lab's growing tanks.
Only the best move on to breed.

Dr. Wilbur and her team of researchers and farmers are well on their way to breeding great oysters that will thrive in North Carolina. I am a huge fan of North Carolina oysters and I'm throwing down the gauntlet: I would put them up against any East Coast oyster, even Moonstones and Glidden Points. Yep. They just need a little hair and makeup. After Dr. Wilbur gets done with them, they'll be as pretty as their cousins. What's not to love about that?

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SF Oyster Nerd tries a
NC steamed oyster

From one love to another … Who doesn't love Hog Island Oysters? Greg Babinecz, the SF Oyster Nerd and a manager at the soon-to-be-reopened Hog Island Oyster Bar in San Fran, stopped by Wilmington, NC, to swap oyster stories and visit the UNCW Shellfish Hatchery. Along with NC oysterman, Ronald Sheffield, we introduced Greg to his first steamed NC oyster. Steaming concentrates the brininess, and the perfect steam pops in your mouth. Thanks for the visit Greg. Looking forward to a West Coast swing in the near future. Check out his oyster blog at sfoysternerd.blogspot.com.

Save the Spat

For some, counting oyster spat is right up there with watching golf on TV.  But for the group of dedicated volunteers with the Oyster Spat Monitoring Project, it's like Sunday at the Master's (or close enough).  The Oyster Spat Monitoring Project tries to determine how many offspring an oyster can produce (an important but difficult number to determine) and how many of those offspring survive.  It's easy with land animals, or egg-laying reptiles and birds.  But measuring oyster larvae - also called spat - is a bit more tricky.  It's thought that a female oyster could lay up to 100 million eggs annually.  But pinpointing that number regionally and by species is like looking for a needle in the proverbial hay stack.

The Oyster Spat Monitoring Project

How many of the millions of spat survive long enough to attach to a structure and finally grow into a harvestable oyster?  At the risk of throwing out another bad idiom, I'll turn to our friend at Oyster Stew and marine biologist Troy Alphin.  (Click here to read a previous post about him.)  He developed this program to actually count spat - casting a wide net over the state of North Carolina to account for the long distances larvae can travel before attaching to a host.  His method, along with gritty determination to keep the program alive, is the backbone of this organization.

The Oyster Spat Monitoring Project is an all-volunteer effort coordinated by the Benthic Ecology Lab at the University of North Carolina, Wilmington (UNCW).  Currently, 35 active volunteers meticulously count spat, collected on Spat Racks, up and down the North Carolina coast.  Volunteers are given a packet of recording supplies and a "Spat Rack." After training for a few hours with scientists at UNCW, all volunteers need to participate in the program is a couple of free hours a month (depending on the time of year) and legal access to a dock.   

Oyster Spat Monitoring volunteers receive
a "Spat Rack," (see picture below) a field journal, pencils,
reference guides, and a thermometer.

Volunteers are asked to place the Spat Rack on top of the mud or sand in the mid-intertidal line and attach the Spat Rack to their dock.  If placed in the correct position, the racks should be exposed to air during low tide and submerged during high tide.

"Spat Rack"
Made from PVC pipe, ceramic tiles, cable tiles and a drain hose.
(Image taken by former volunteer coordinator Heather Stoker)

Oyster larvae are able to survive without a host - something to attach to - for about two weeks.  If they don't find something to attach to during those two weeks, they will die.  Desperation often leads to inspiration, which explains why if an oyster can't find another oyster shell to call home, they will attach to just about anything.  

Oysters attach to ceramic tiles on the "Spat Rack."
(Image taken by volunteer Preston Somers.)

The Oyster Spat Monitoring Project uses ceramic tiles to make it easier to count the oysters and is a good substitute for oyster shells.   Every six weeks, the volunteers count the live baby oysters that have attached themselves to the structure and record their findings.  They are also asked to identify and record other organisms, such as slipper shells, mussels and snails, that settle on the ceramic tiles.  Volunteers also collect environmental information such as air and water temperature, water salinity and weather conditions.

What have they learned from this project so far?  I'll let Troy Alphin explain:

"Over the last few years we have found that oyster larvae remain in the water column in the southern area (from White Oak River and areas south) longer than in the central and northern regions of the coast.  So it is not uncommon to get oyster settlement in Nov.  Also, oysters respond to dramatic changes in the weather so that we sometimes see a pulse of larval settlement following coast storms in the late fall."

Smarty pants ... Thanks again Troy!

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 The Oyster Spat Monitoring Project is always looking for more volunteers to keep an accurate count of the oyster larvae in your area.  If you live in North Carolina, have a couple of hours a month, and have legal access to a dock, contact Megan Rudolf at rudolfm@uncw.edu.  To donate to the program, please contact Troy Alphin at alphint@uncw.edu. For more information, visit www.ncoystermonitoring.org.  And, if saving the oysters isn't incentive enough, check out the thank you gift each volunteer received at Christmas last year ... 

Troy Alphin and his family hand-painted
oyster shells to make Christmas ornaments
for all the Oyster Spat Monitoring Project volunteers.  

Oyster Geek and Oyster Freak

Troy D. Alphin
Center for Marine Science - UNCW

I'm an oyster geek.  There are few topics that interest me as much as oysters, which is why I was so excited to chat with Troy Alphin, Senior Research Associate at the Center for Marine Science at the University of North Carolina, Wilmington (UNCW).   He's an oyster geek-in-residence and talks about the lowly oyster with whimsy, admiration, passion, and, above all else, respect. With a bachelor's and master's degree in marine biology, Alphin is currently working on his doctorate in marine biology.  His doctoral project is trying to answer the question: What does a happy oyster look like?

"Think about it, if you go to a restaurant or grocery store or even see them in their natural habitat, how do you know they're happy?"

Did I mention that we were talking about the no face, no legs, no arms, no brain oyster? Happiness seems elusive.

He's still researching telltale signs to determine if an oyster is happy, but he is willing to give us some clues.  He calls them "ecosystem engineers" (fancy).  " Once established, they engineer the environment around them."  They attract mussels and oysters, trap nutrients, and filter the water.  They can even, in some regions, such as North Carolina, save us from storm surges.  Panda bears and kitty cats may get more attention, but none of them can do all that.  When the oyster is allowed to do their job, they are happy.

Even super studly, uber happy engineers, though, need a little help from us.

HELP SAVE THE OYSTER BABIES 

Millimeter comparison.
From http://waynesword.palomar.edu

"One of the biggest problems facing oysters today is the oyster larvae," Alphin says.  The oyster larvae is 1/10 of a millimeter.  To understand how small that is, try and touch your thumb and pointer finger as close together as possible without them touching.  Oyster larvae are 1/10 the distance between your thumb and finger.    Oyster larvae survival depends on their ability to connect to an existing structure, usually another oyster shell. However, sediment from runoff settles on the oyster shells.  The sediment is 1/2 mm, five times the size of a larvae, which makes it incredibly difficult for the larvae to find its own spot on a shell.  If the larvae can't find a place to nestle onto the shell, they will die.

That's where we come in.  We all have to do our part to help alleviate storm water runoff.  If you're lucky enough to live on a creek or estuary, make sure to leave the edge of your property in it's natural state.  Minimize or alleviate chemicals both inside your home and out.  And don't discharge anything directly into the water.

DYING YOUNG

Freak of Nature?
Fossilized oyster shell is at least
a foot long and probably
35 million years old.

Even those oysters who find a spot to grow face limited prospects.  We've come to accept that oysters live 4-5 years on the East Coast and grow to about 3-4 inches.  But just 100 years ago, oysters harvested from the waters outside New York were 6-8 inches.  Today, even in protected areas, oysters aren't living long past their cousins in open, harvested waters.  "Why?" he asks.  "There's no programmed death for oysters.  It's got to be the environment.  It's got to be ecological."

Why is it important that oysters live longer?  The longer the oyster lives, the bigger the oyster grows.  The bigger the oyster grows, the more eggs a female can produce.  The more eggs they produce, the more larvae.  The more larvae, the greater number of oysters.

PEARLS OF WISDOM

Because Alphin is both a biologist and oyster eater, I thought he was the perfect person to ask the two most important questions that nag oyster aficiandos:

1. Do you eat raw oysters? 
"You should always cook your oysters," he says.

2. Do you eat (non-triploid) oysters in non-R months?
"Yes, as long as they're cultivated.  And they're cooked."

And that's all he'll say about that.  I, however, remain loyal to raw oysters.  And that's all I'll say about that.

Thanks for working every day to help save the oyster, Troy.