Post-conference science tornado!

Long time no post, everyone. The conference was a smashing success– I met some other scientists and industry folks who are interested in aquaponics, and we’ve been email-storming each other ever since. The downside is that that has taken up time normally used for blogging. Alas, it takes time to hatch a proper bit of mad science. 

The main takeaway from the conference (for me anyway) was that before AP can really move forward, we need to figure out some fish-friendly ways to control pathogens– both fish diseases and foodborne pathogens for people. 

This appears daunting but doable.  Commercial aquaculture (in the West) only began 20-30 years ago, so veterinary care for fish is still in a fairly primitive state. One of the most common treatments for parasites on fish is formaldehyde. Needless to say this will not fly in aquaponics.

Coming from a horticulture background gives an interesting perspective on this situation. 70 years ago the state-of-the-art in plant health was lead arsenate. People loved it– it killed fungi, bacteria, AND bugs! What’s not to like? But the end result is that now there are romantic old orchards where you can’t eat anything that comes out of them because the soil is full of lead and arsenic. 

Nowadays for crop care we have some sweet high-tech tools like clay particle films, mail-order predators and parasitoids, bugscaping, banker plants, SAR elicitors, and so forth. I think we can get there with fish and foodborne pathogens. There already exists in nature a wealth of possible tools like cleaner wrasses, quorum sensing, bacteriophages, working with bacterial biofilms to get benign bacteria to outcompete pathogens, and so forth. And science has sped up considerably since the lead arsenate days, so I don’t think it’s going to take aquaculture 70 years to get there. 

First day at ISS7: Touring the Northern Divine caviar farm

There’s an organic caviar farm, Northern Divine (http://www.northerndivine.com) in Sechelt just across the Straits of Georgia from Nanaimo where the conference is located. The best way to make a quick trip across the strait? A little teeny bushplane with floats.

/insert glorious angelic choir sound/

A common feature of BC beaches: lots and lots of driftwood.

Our pilot with his trusty 1952-vintage steed.

Some folks from Northern Divine picked us up from the floatplane dock and brought us over to the facility. They have people come through on tours all the time, so they’ve got windows for easy checking-out of the caviar making process without having to track through and disrupt everybody.

Hard at work in the caviar mines

The way traditional caviar harvest works is slaughter the fish, remove the ovaries with the eggs all still attached to the membranes, and then rubbing the mass across a screen to separate the eggs from the membrane. A couple of the guys on our tour have caviar farms of their own, so they were discussing the ins and outs of getting the fish to a nice healthy size without overfeeding to the point that lots of fat accumulates on and in the ovarian tissue– leading to weird flavors and poor yields. One related how at the very beginning of their operation, they knew that caviar yield was about 10% of body weight. They fed the fish as much as they would eat so as to have bigger fish. The end result was about 2% bw worth of caviar and lots and lots of sturgeon grease. Oops….

Tables for cutting sturgeon. (Ice machine in the background.)

This is the stretcher where they hold the fish for gutting. Ovaries go in in a container and pass through a window to the caviar room for screening. (They want to keep whole fish separate from the caviar.) Everything else gets filleted.

Kettle bells

The most important part of turning eggs into caviar is adding salt. Like most things, sturgeon eggs release liquid when they encounter salt. As the volume shrinks you need to press on the tin to shrink it down and get the liquid out. Pretty much the same deal as pressing the whey out of cheese– with the exception that in caviar you’re not trying to fuse individual eggs together the way you do with cheese curds. You want to remove just enough that they’re not gloopy but not so much that they get dry. What did they find out was the perfect size & shape for getting the job done? Kettle bells.

Stay tuned for more ISS7 caviar loveliness all this week!

This coming week: International Symposium on Sturgeon!

There’s been a lot going on this week, but I wanted to let you know before things got swinging– 

It’s time for the Seventh International Symposium on Sturgeon! This is a quadrennial global get-together of everybody involved in the sturgeon world– from ecologists to caviar farmers to caviar businessfolk to gourmets. It’s kind of a big deal. And I’m very excited, here in my very first year at the conference, to be leading a discussion on Wednesday on the possibilities for aquaponics with sturgeon. The goal is to both gauge interest and to identify technical issues on the fish side that might have to be addressed before AP could work with sturgeon. I know plants very well but don’t have as much experience with fish by a long shot. The sturgeon farmers attending this meeting are the ranking world experts on raising these fish, so getting their input will be crucial. 

This year the ISS7 in Nanaimo, British Columbia, and I’m in Florida. Which is why it’s 5:30 am and I’m in an airport. (Pro tip: it’s pronounced nuh-NYE-mo, at least according to the gentlemen I booked a floatplane with. Floatplane! More on that later. British Columbia is a happy place so I trust that this pronunciation is not something they tell tourists to mark them for easy pickings.)(Can you tell I grew up in Miami?)

Stay tuned for live blogging and/or tweeting here and at my twitter account, OwlSpringsFarm. 

Science Monday! When life throws you gamma rays

About ten years ago, a research team sent a remote vehicle down into the reactor pit at the old Chernobyl nuclear plant. You know, just to say hi and see how things were going.

Hey there, frozen pile of once-molten rock and nuclear fuel lava! Long time no see!

When you’re deep in the heart of an area spewing out enough radiation that rad suit-clad workers building a new containment sarcophagus are only allowed to work five-hour days, you expect pretty sterile surroundings. So you can imagine the scientists’ surprise to see the walls covered in gooey black stuff… that looked suspiciously like the crud growing in a bachelor pad shower.

That that black goo indeed turned out to be made of three common species of fungi: Cryptococcus neoformans, Wangiella dermatitidis, and Cladosporium sphaerospermum.  (Warning: don’t image search these right now if you’re trying to eat.) Some strains of these species apparently had adapted to live in extremely high-radiation environments. But these fungi weren’t content to just survive.

They were eating the radiation.

Run, puny human!

Evidently these fungi grew pretty slowly when they were brought back to the lab. Somebody got the bright idea to try putting the samples in a box with a source of gamma radiation inside. Bingo! The fungi perked right up. Later MRI scans showed that the radiation exposure was altering the spin state of atoms inside molecules of melanin in the fungus. In other words, melanin was intercepting the radiation, and the fungus was somehow turning that energy into growth.

These badass Basidiomycota had learned how to photosynthesize. Not with normal visible light like plants do, mind you. With motherloving GAMMA RADIATION.

The revelation that it’s possible for some life forms to not only live in the presence of high levels of gamma radiation, but to put it to constructive use, brings up a lot of really interesting possibilities. None of the fungi at Chernobyl make edible mushrooms. In fact all three of them are opportunistic human pathogens– if you didn’t listen when I said “Don’t look for pictures of these if you’re trying to eat,” by now you know why! C. sphaerospermum is also a common cause of sick building syndrome. It’s almost like… Chernobyl doesn’t want us back?

Despite radiation, with humans gone wildlife like these reintroduced Przewalski’s horses are thriving near old Chernobyl

But now we know it may be possible to develop edible fungi with a high melanin content that can intercept cosmic rays and turn it into deliciousness. One can only imagine how useful it might be to have a sun-fuelled protein recycling system in space.

Other nifty uses for melanized fungi here. Article on physiology of the Chernobyl radiotrophic fungi here.

Summertime and the foraging is easy

Frog and Mushroom Season* is here! It finally dried up a little bit this morning, so I headed out to a big live oak tree in our apartment complex where I saw some chanterelles last year. I found the patch right at the end of summer, so have been eagerly awaiting hot muggy weather (for once) when they would return. Was not disappointed!

Chanterelle party in my hat!

It’s a little hard to tell in this photo, but these are not your average chanterelles. They’re TRAFFIC-CONE ORANGE. Why? Because Gainesville is where the Deep, Deep South starts to slowly drip into the tropics and we don’t do anything normal down here y’all.

You often hear mushroom-hunters talk about the deep intimacy with the forest required to find mushrooms and learning to read signs in the duff. That sounds awesome. It is however not an experience had when looking for neon-orange mushrooms against a grassy green background. I have to say that being a busy postdoc, I do appreciate their efforts to make themselves visible. They’re like little good ol’ boys in hunter vests doing their best not to be mistaken for deer.

The danger with urban foraging is that eventually people will notice that this lady keeps coming to their front yard for the mushrooms and realize they’re edible. We live in grad student housing and free food is really popular here! My main hope is that people will steer clear of eating things the color a safety hazard warning sign. If anybody asks I can always tell them I’m collecting them for a science experiment. They don’t have to know the experiment involves a lot of butter and a frying pan.**

**Experimental results indicate that this mushroom is a delicious, tender, crispy conveyor of butter and salt

These are properly known as cinnabar chanterelles, Cantharellus cinnabarinus. Local mycophiles tell me it’s “not the best chanterelle but it’ll do.” Traditional chanterelles evidently have some fruity apricot-like aromas. This sounds very lovely but alas, I don’t think we get “real” chanterelles down here. That’s ok. I cooked these last time in browned butter (why? because I got distracted while the butter was melting, that’s why) and still found myself daydreaming in odd moments about how good it was for a month afterwards. One shudders to imagine how these neurons would fare in the presence of “good” chanterelles.

*Frog and Mushroom Season: Gainesville’s way of reminding you that the tropics start somewhere around 16th Ave. Begins in mid-June and ends when rain stops 6-10 weeks later. Toadstools sprout, flourish briefly, develop an Einstein-hairdo-like coating of parasitic fungi and dissolve into mush; eg, it rains long enough for mushrooms to sprout mushrooms. Tree frogs go on a mating frenzy and descend to the ground en masse. Up to three at a time may attempt to leap into your house at any time when you open the door, leading to a Marx Brothers-esque routine of shooing out multiple tiny inch-long creatures that can jump 6 feet in a single bound. You succeed in liberating two and lose the third only to find it mummified in one of your sneakers the next morning where it tried to wait out the night in the moistest place it could find. Frog and Mushroom Season.

Food safety in aquaponics pt. II: how does it compare to field production?

Let’s look at how lettuce and other leafy greens are normally grown in the field. Ideally they’re watered by drip irrigation. But drip systems are expensive, and a lot of farms still have legacy sprinkler-type systems like the one you see on lawns. They spray water right over the crops. Sometimes the water comes from wells and other potable sources.  Sometimes it comes from the Colorado River or other ponds, streams, or rivers. These aboveground sources are called “surface water” in the ag biz, to differentiate it from groundwater coming out of wells. Wellwater is nearly always clean, unless you have a feedlot or something else grody going on nearby.

Wisdom from the children’s publishing industry.

Surface waters have fish in them. That’s the way lakes and streams are supposed to be: lively! The water has fish poop in it– not to mention poop from deer, coyotes, raccoons, cattle ranches where cows hang out around any available water stream, and campers. And unlike aquaponics where the water stays down in the root zone at all times, they’re sprinkling it right onto the parts of the plant you’re going to eat.

This is 100% legal even under the most stringent on-farm food safety standards in the country, the California Leafy Green Products Marketing Agreement. (Adopted by CA farmers after the 2006 spinach scare.) Want to read it yourself? Link to the LGMA rulebook here. Standards for using surface water in overhead sprinklers are on p. 16.

You’ll note that the water has to be tested at least once a month. You’ll also note the caveat about how rainfall and other occasional events can spike the bacterial levels in water, and how the limit is 235 cfu/ml averaged over the last five samples. Bacterial loads in outdoor water bodies can be extremely variable– they can be clean most of the time. But when a rainstorm washes junk into creeks, or a neighboring rancher lets his cows into a paddock that your source stream runs through, or a critter drowns in your pond, it can go up really fast. This report on the involvement of cattle and wild pig feces in the 2006 E. coli outbreak on spinach gives a good perspective on the wild world of irrigation with surface water.

An ad I found today for a tractor attachment that makes these little soil dams in the furrow, so that irrigation water stays ponded on your lettuce instead of running off. (Granted, this is very good soil and water conservation. Questionable food safety though.)

I wouldn’t say the LGMA’s standards are lax. They’re literally the best you can do in an outdoor situation where there are so many factors out of your control.

Field crops also have a hard time with critter control. A major food safety issue in field production is that birds, mice, rats, squirrels, and deer like lettuce too, and eating tends to lead to pooping. It’s extremely difficult/impossible to keep critters out of a big sprawling field of a couple dozen acres and upwards.

Aquaponics done right: so clean it’s almost annoying. Source

Aquaponics, by contrast, is a very compact system. A conventional lettuce field can turn out maybe two, three crops a year. Aquaponics can do 10 to 20. The area needed to grow lettuce for a certain size of market is much smaller. At that concentrated size it’s actually possible to fence and screen vermin out.

Low water use is also a food safety advantage for aquaponics. When plants in the field need water they need it NOW. You may studiously avoid taking samples when you know that upstream neighbor Bob has his cows in the creek again… but that probably won’t stop you from using the water.

By contrast, aquaponics uses a contained body of water that you can keep critters out of without needing neighbors and the weather to cooperate. It only needs to be topped off rather than completely re-watered on a regular basis like a field. If there’s a supply problem you can wait until it clears up. Together these mean that it’s much more possible to take real responsibility for your bacterial levels than it is in a field situation.

Questions?

Food safety in aquaponics: keep them veggies clean!

One of the first questions people ask about aquaponics is “Fish poop? Gross!” (Ok, that’s not a question.) But it is an astute concern. Let’s talk about what we currently know in the realm of aquaponic food safety.

The delicate art of on-farm food safety. Too casual and you hurt/kill people. Too far and people start wondering if your romaine is undergoing treatment for tuberculosis…. (source)

Because of the scarcity of land and fresh water, aquaponics is very popular in Hawai’i. The University of Hawai’i has been busting its butt to get good data on AP food safety so that the state’s growers can get food safety certification and thus sell to grocery stores. This surge of righteous gumption puts Hawai’i on the cutting edge of aquaponic food safety knowledge. UH put out a landmark study last year checking the levels of coliform bacteria in aquaponic water on 11 farms on three different islands in Hawai’i (link here).

As you can see in the study, most farms had extremely low counts. There’s a legal limit to how many coliform bacteria can be in water sprinkled directly onto plants for irrigation– for the curious, it’s 235 cfu/ml. Most of the samples collected were down near zero. There was one farm that had a day that was by far the dirtiest of all samples collected– making it all the way up to around 110-115 cfu/ml, or almost half the legal limit. That upper limit of 235 cfu/ml, by the way, is the EPA cutoff for what’s safe to swim in. Agriculture borrowed that number because we’re too lazy, I mean efficient to replicate efforts already done elsewhere.

UH also developed some food safety “good agricultural practices” for aquaponics, which you can check out here. These are guidelines on how to keep your crop clean. They include common-sense things like only topping up your system with clean potable water, keeping out critters, and washing your hands that are important to follow on any kind of farm. Aquaponics gets a couple extra rules like “if you touch the roots, wash your hands before touching the leaves again” and using gloves when you’re digging around in gravel beds. (At least in Hawai’i, they tend to use volcanic cinders as the gravel, and it’s sharp and can cut. Sad times for eaters and workers.)

It’s one thing to grow things in your own garden with half-baked hygiene. But when you’re growing food for other people, that’s a very serious responsibility. I’ve had the pleasure of working with the scientists from University of Hawai’i as well as fellow Floridian Gina Cavaliero of Green Acre Aquaponics to keep developing good info on AP food safety. I’m hopeful that this work can both help aquaponics to gain wider acceptance with food certifying agencies, and result in information that helps aquaponics growers to do our best possible job.

Vegetable food safety: no laughing matter.

Epidemiology of spinach pt. II

Growing spinach in hydroponics is basically a race between the spinach and Pythium. Fortunately for us, the good people of Cornell have done a lot of work figuring out how to help tip things in favor of the spinach. Brief reports here.

First of all, it turns out there’s a temperature tipping point. Above it, Pythium grows faster. Below it, spinach comes out ahead. That temperature is about 20C (68F).

So, the first step to avoiding sudden death by Pythium is appropriate temperature. That’s why it’s very important in aquaponics to match species of plants and fish that grow in similar conditions. If you tried to grow spinach with tilapia– whose favorite temperature is somewhere around 30C (85F)– at least one of those species would be very miserable. On the other hand spinach would probably do very well with some freshwater salmon relatives like trout, Arctic char, or grayling. Spinach and salmonids both like their water bracing and chock-full of oxygen.

Look at that gorgeous fish! It’d be worth growing Arctic char just to look at them! (They also smoke well. All in all a good deal.)

So do sturgeon… sometimes. They tolerate cold very well but grow best around room temperature. What cold is good for with sturgeon is cuing them to begin forming eggs. Thus there may be a place in sturgeon-based aquaponics for a cool-water hydroponic plant like spinach (and other winter greens like mâche, radicchio, endive, etc). Being able to nudge a fish to begin the spawning process by imitating natural seasonal cues means that you know when it’ll be ripe. Obviously you don’t want a fish suddenly losing her eggs all over the tank because you didn’t know to milk in time. Another potential problem is that the fish simply reabsorbs the eggs when she decides the tank isn’t a good place to spawn. That can be ok once or twice, but from what I understand it can be bad for the fish’s health if this occurs too many times.

There are some other cool things you can do to help the spinach pull ahead. Fungal and bacterial pathogens grow 24/7. Plants only grow when there’s light. Drawing out the light period can do some amazing things for plant growth– as evidenced by Alaska’s annual summer takeover by giant killer cabbages.

M’lady’s coleworts are going to start eating frogs and demanding Han Solo in carbonite any day now.

All it takes to grow Cabbage the Hutt is 20+ hours of sunlight a day. Piping in extra CO2 is another way to boost growth. This technique is actually pretty common in the Netherlands where they have to keep the greenhouses sealed up tight to keep the warm air in. The plants can run out of CO2 by mid-morning on a bright winter day if you don’t keep adding more.

Both supplemental lighting and CO2 are quite intensive and not something you’d do for a home garden, unless you simply have to have 93-lb cabbages for some reason. But they do speed up growth enough that they can pay off if you have the right commercial market. The Dutch have done very well for themselves by using these kinds of techniques just to increase yield on their small land acreage. There may well be a place for them in US farms close to urban markets where land is at a premium.

Well, that’s it for today. Moral of the story: spinach needs environmental conditions that push you more towards an intensive, tightly-controlled Dutch-style production model if you were to grow it in one place year-round. The US is large enough that there’s almost always someplace that’s enjoying the right weather to grow it so our markets have leaned more in the nomadic outdoor production method. American growers have been loath to adopt high-production greenhouse techniques. Now you know why you’ve never seen hydroponic spinach at the grocery store– and why that may change as transportation costs go up and local food grows in popularity.

Epidemiology of spinach

With a mascot like Popeye, you’d think spinach would be the burly lumberjack he-man of leafy greens. But you’d be wrong! It’s actually quite the diva in the greenhouse.

believe it or not, this cartoon was not entirely truthful about spinach’s magic powers.

Spinach plants’ roots are especially vulnerable to “summer Pythium.” Pythium is usually grouped in with other “damping-off” pathogens like Rhizoctonia and Phytophthora (the one that killed potatoes and indirectly also several million people in Ireland): diseases that flourish in cool, wet conditions. But it turns out there are some funny-looking stepchildren in the Pythium family that like it hot.

Like all plant diseases (or diseases period), there are certain settings where the pathogen grows faster than the host. Most plant diseases really get off on low-oxygen conditions. This is especially true of those that affect the roots. Root can’t make their own oxygen– photosynthesis is the leaves’ department!– so they have to absorb it from the outside environment to function. And, remember that the warmer water is, the less dissolved gas– like oxygen– it can hold. So the warmer the hydroponic solution, the more oxygen-stressed the roots are, the worse the entire plant’s health becomes as a result, and the more fat and sassy the Pythium gets anyway. It’s a recipe for disaster.

And in hydroponics, whenever Pythium gets a good beachhead, it gets massively ugly in a hurry. Pythium is spread by little spores that swim. In soil they can only swim so far. But in hydroponics where the water is constantly whooshing around unobstructed, they can infect the entire system in a day! You go to bed one night and everything’s all normal, and the next morning the spinach is all flopped over and crying out for morphine.

An oomycete zoospore on the prowl! Look at that sinister Cyclops face. Clearly this microbe is up to no good.

Growing spinach in hydroponics is basically a race between the spinach and Pythium. Even in conventional hydroponics it’s difficult to control Pythium with fungicides– you have to stop using fungicides for at least 1-3 days depending on the fungicide before harvesting the plants, and that’s plenty of time for Pythium to eat them alive. In aquaponics it’s especially tricky because most if not all fungicides are toxic to fish. You can’t use them ever.

So what CAN you do to keep Pythium at bay in hydroponic spinach? Stay tuned…

My notochord will go on

We bring you an important update in the vein of nose-to-tail eating.

True fact: modern sturgeon don’t have vertebrae.*

They do have a cartilaginous sheath around their spinal cord, called a notochord. When you’re cleaning a sturgeon, you can yank it out like a big white noodle. It’s considered a delicacy in Russia called vesiga. Not only that, but it was used on a garnish on a soup called Consommé Olga** in the last meal served on the Titanic.

Do I smell… spinal tissue?

It turns out you can still get your hands on some vesiga here in the 21st century. Acadian Sturgeon— a sturgeon farm in Canada– sells not only caviar and sturgeon’s reputedly amazing swordfish-like meat, but more exotic bits as well including vesiga (labeled here as “cartilage and bone marrow”).

*Sturgeon apparently started off with a normal vertebrate skeleton eons ago, then decided bones were unnecessary and got rid of them. Their body structure is now quite minimalist. I almost said bare-bones but it’s gone rather beyond that by now….

**I had no idea, but apparently Titanic reenactment dinners are a thing? Classy recipe for Consommé Olga here. Hilarious review of soups from all three passenger classes here.

My notochord will go on