I have been made aware of a section in the latest newsletter of an aquaponics trainer making some rather interesting statements around the risk of introducing "deadly" E. coli HO157:H7 into aquaponics systems through the introduction of worms.
Like most promotional material, it contains enough reference to some form of correct base statement to make their argument appear compelling, but I have found the way that the section was written distressing in many ways. On one front, we are trying our level best to ensure food safety and hygene in our units and to educate people on the safety of aquaponic production methods. To have someone from within the community write something down the line of "if you dare put worms in your system you run a very real risk of introducing a deadly pathogen into aquaponics" is not conducive to building a fair and realistic impression of aquaponic production methods. Worms in media beds have been in use for many years outside of the design of the group in question, with no reports of any health issues.
The inference made was that (without stating how many worm growers use cattle poo) red wrigglers are likely or potentially all grown in manure from corn fed cattle and this all contains the "man made" (?????!) strain of E. coli that will then most likely survive the transfer from worm to your system where you will contaminate your crops, your family or your customers. If you are extra unlucky, a fly from a pasture containing corn fed cattle poo will also do the trick (then why bash the worms?) if they can make the trip in under 10 seconds.
The article would have had more use if it simply said something down the line of "pick your worm supplier carefully - if you are cautious about E. coli, steer clear of using worm growers that cannot guarantee that their worms were not fed corn-fed cow poo from feedlots." I do not know what the ratio is of worm producers that potentially use this feed method compared to those that do not, but if it is the case that very few follow this practice, this article borders on reckless. Then one can write follow-ups warning people on the next one in a gazilion risk such as a bird-flu contaminated duck landing in your fish tank. As stated before, in theory, the conditions described in the text can potentially occur. Just as, in theory, a monkey can sit down in front of a typewriter, hammer away at it and write something recognisable. Not impossible, but likely?
I wrote a blog a while ago about the responsibility of perceived role models in the industry related to statements made and perceptions created from a "credible" source. This type of statement was exactly what I was talking about. Not worth the negativety and not worth the potential bad press and poor PR for what many aquaponic producers see as a staple - media filled beds with worms in them (is there a reason for this?). As a scientist, I would like to see some concrete evidence related to instances of the scenario described having been observed at worm farms and in aquaponic systems. If no such data exists, is this statement fair and accurate? Why was it made? I do not want to appear to downright rubbish their concerns, but I will appreciate a percentage risk description to back up this claim.
I received and read the newsletter today---and was puzzled by the content---because a year ago I was shown a worm found that day in their system.
Wondering if they had changed their mind about worms, I opened the author's website main page and it still states "In contrast to hydroponics systems, where the aim is to have a sterile system to avoid disease outbreaks, aquaponics systems are teeming with life. They are miniature human-made ecosystems: there are mosquito fish, prawns, tilapia, water fleas, and little red worms in our systems."
The forums I read contain many references to worms finding the postee's aquaponic system by themselves---and it's beeen viewed as a good thing.
I too was puzzled by this newsletter. First, there is the lumping together of compost and worms. While they may arrive together, generally most AP gardeners I know don't ever add compost to their systems...they just add worms and let them do their job of converting solid fish waste into excellent fertilizer. Second, there is the unreasonably strong assertion that adding worms to your system could kill someone "incorporating worms that may have been in manure and may carry E. coli with them is not the inability to achieve organic certification, but the very real possibility that your produce (contaminated with E. coli H0157 from the compost and/or worms you added to your aquaponics system) kills someone who eats it uncooked." I'm with Kobus here...what is the chance of that, seriously? Add anything that has been in contact with raw manure to your system and you risk e. coli. The fact is that worms are one of nature's great clean up crews, and in the truth is that there is something inside the worms that actually destroys pathogens and vermi-compost is actually pathogen free. Scientists have actually spiked manure piles with E. coli, added worms, and watched the pathogens die-off rather than multiply (see the highlighted section of the attached article). Their entire issue seems to be with improperly decomposed compost...which no one (anyone?) uses in AP...and yet they are extending this to the worms that are actually working to digest and render those pathogens harmless. Bizzare, and somewhat reckless, frankly, given how many people this newsletter reaches.
I have to agree that I also found the newsletter problematic.
I am one of the first people to say........ NO uncomposted warm blooded manure in my salad and recommend to others not to use birds or other manure for aquaponics.
As to composting and manure. Manure must be properly composted for the right amount of time before it can be used. If fresh manure is spread on fields the withholding period before harvest must be 120 days. And in my book COMPOSTING is the ONLY good way to deal with pathogens in manure (all manure including human) and flushing it away doesn't actually take care of the problem.
Now I wouldn't want to use lots of fresh worm castings made from worms fed on manure to make a vermicompost foliar feed for my lettuce. While worms are very good at taking care of things, you can't really guarantee that the fresh stuff didn't touch the finished stuff in most worm bins and the holding time in worm bins is generally less than 6 months and so not long enough to ensure safety by time if the composting microbes and worms didn't manage to process every speck.
However, if you let it age, it might be ok though you loose some of the benefit of the active good microbes if you let the worm castings dry out too much.
Anyway, I don't use fresh manure in my worm bins and they are screened to avoid flys and I'm not near any feed lots so I figured a few worms added into my aquaponics system were a fine thing.
And even if you don't add worms directly, if your system is outdoors or you ever transplant a soil seedling into the system, you will probably find worms in your system eventually on their own.
Somehow I never got the newsletter this time but I do know that the same people on their website say that aquaponics eliminates mosquitoes on their property. Thus aquaponics could be used to eradicate mosquito born diseases. ( using mosquito fish in tanks and troughs). I can say this that last winter we were eaten alive by mosquitoes on my property because of the excess rain. We only have had a reduction of mosquitoes in the last month. You will not find a mosquito larvae in my tanks or troughs but they come from somewhere.
Glen Martines uses worm castings in his aquaponics and he sells castings. He uses chicken manure for the worms but he has built a apparatus that sanitizes the castings. He invented this thing and all castings are sent through it making them safe, I have seen it in operation. He got a grant to make it.
I have a "Worm Factory 360" and continue to make my compost and grow red wigglers and use them in my media beds. Now I do not use and external manure but just add Coir to my compost items. Using this method in Aquaponics I have not experienced any problems and hopefully will not :-).
Adding external manure to your system or where you grow your red wigglers may...I am not an expert in this field so leave that to those who are.
Raychel, here is the article we are referring to....
Compost In Aquaponics Equals Dangerous Aquaponics Systems
It is a little-known fact that humans are the ones who created E. coli H0157:H7, the only E. coli that as few as eleven of can kill an otherwise healthy adult human being. The story is quite simple: someone had a good idea to take cows, which had been eating grass for tens of thousands of years; put them in a confined space (a feedlot), and feed them corn and other grains to make them grow fat and valuable in a relatively short time.
Unfortunately, this idea didn't take into account the fact that cow's digestive systems are NOT designed to digest grain; and they become acidic when they try to do so. A new bacteria that had never before been seen grew in the newly acidic cows stomachs, and that bacteria was E. coli H0157:H7. So, as with the fabled Snake in the Garden, the Fall occurred. We can't go back to a time where there is no E. coli H0157:H7, we simply have to deal with it and keep it from killing us. How does this apply to aquaponics, and to the vegetables in YOUR system?
Some aquaponicists are doing really good things with their projects. However, others don't have a clue how dangerous what they're doing may be.
If you introduce compost and/or worms into your aquaponics system, you run the risk of bringing in dangerous or deadly varieties of E. coli such as H0157, 11 of which can kill an otherwise healthy adult human. There are 13 other species of E. coli that will make us very sick but not kill us, and they all come from warm-blooded animals and their excrement. This is why pure aquaponics systems where the only animals involved are cold-blooded fish are safe from these deadly bacteria. In fact, we
drink the water from our systems and have for nearly three years now without ever having a reaction, illness, or even a bout of intestinal discomfort.
Worms that have been bred in compost with LOTS of E. coli contamination, or compost containing LOTS of warm-blooded animal manure are safely usable on field crops according to organic certification standards. However, there is a requirement that the most recent application of such compost or worms (or worm castings) be at least 120 days prior to harvest of the produce. If your compost doesn’t contain manure, the problem is something else entirely, especially if you want organic certification.
If this is the case, you can’t use the compost because there is no way (currently) to prove to the satisfaction of the organic certification agencies that the compost truly does NOT contain any E. coli, and is safe for use. If you go ahead and use the worms or compost anyway, doing so will jeopardize or eliminate the possibility of your ever getting organic certification. This not only means your produce is worth less to the market, but also that you cannot ever legally use the word organic in your packaging or on your product or you will face a $10,000 fine per occurrence (which can mean per 1/2-pound bag of product!).
The REAL problem with incorporating worms that may have been in manure and may carry E. coli with them is not the inability to achieve organic certification, but the very real possibility that your produce (contaminated with E. coli H0157 from the compost and/or worms you added to your aquaponics system) kills someone who eats it uncooked.
If we can develop composting systems that only use vegetable inputs and never any from warm-blooded animals, and keep them uncontaminated, then there’s a chance that we can obtain organic certification for the use of these systems (and their worms) in conjunction with aquaponics. Unfortunately, a visit from a single housefly that visited a pile of excrement ten seconds before is all that’s necessary to contaminate the compost, and compost is attractive to houseflies in a way that a row of aquaponic plants is not. This kind of technology needs to be carefully and methodically developed and tested before we depend on it to give us healthy food.
Now, having said all that, IF you are going to cook EVERYTHING that comes out of your aquaponics system to at least 165 degrees for at least 5 minutes (as the Chinese do), then you are safe from E. coli H0157, and you can go ahead and use whatever you wish in the system (even “night soil” as the Chinese have been doing for thousands of years!).
Please refer to my response at the link below on another similar thread:
If people are still "worried" about introducing redworms to an aquaponics system from wherever they may be living, there is another option. Introduce redworm cocoons. Redworm cocoons are very hardy, much moreso than the worms themselves. You can add the cocoons to your media-beds, or even hatch them in damp (pre-sterilized) towels or cotton fabric even. And yes, you can dampen the fabric with sterile water. A bit extreme, but it can be done.
The cocoons look like pearlescent green grape seeds in size and shape (kind of tear-drop shaped) , and turn brownish when they get closer to hatching time. If you do not have cocoons, you can buy them just like you can buy redworms, but most redworm farms do not sell the cocoons. They are harder to find on the market.
Of course, no redworms in an aquaponics system is fine.
I'm on my way out of town for a bit now...Looking forward to catching up when I get back.
Wow! Thanks Converse and Sylvia for providing incredibly logical and educated explanations. What really seems to be the main issue in this article is the implication that the worms themselves are the culprit for potentially causing the incidence of E. coli H0157 in an aquaponic system whereas it is the introduction of the worms depending upon their origination that is the problem, not the worms themselves. Research concludes that worms actually reduce the incidence of E.Coli and other dangerous pathogens, certainly not that they generate them! So perhaps what would have been much more of an accurate assessment of the likely introduction of such pathogens is some external source producing the contamination. However if that is the reason for concern, then one must conclude that a system then must be impervious to any other sources of external contamination in order to be absolutely safe. A fly, a cat, or a child could just as easily or even more realistically be the fateful carrier of a pathogen.