What is Hydroculture?
According to Wikipedia, Hydroculture "is the growing of plants in a soilless medium, or an aquatic based environment. Plant nutrients are distributed via water." It's the umbrella above hydroponics and passive-hydroponics. Both of these growing methods are soil-free with the nutrients being dissolved into the water. The difference between them is that regular hydroponics uses a pump to deliver nutrients to the plants while passive hydroponics has the plant suspended in the water with no moving parts.
So, what's Aquaculture?
Also according to Wikipedia, "aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, mollusks, and aquatic plants." As noted in other places in our blog, it is a huge industry with many sub-sectors from mariculture (marine-based aquaculture) to pond-culture (self-explanatory) to recirculating aquaculture. Basically if it includes growing fish or marine life, the operation fits under the umbrella of aquaculture.
Let's work backward and start with the "culture" part of hydroculture. In Latin, the word agriculture came about in 1440 roughly translating to "the tilling of the land." So it makes sense they needed to add something about water on the front of it for hydroculture. Going a little deeper, "culture" can be broken down into it's two Latin roots. "Cult" stems from the Latin cultus meaning habitation, tilling or refinement. "Ure" is derived from the Latin root ūra which translates to "indicating act, process or result." That makes sense, so the "culture" of hydroculture can be worded as the act of tilling or refinement.
So what about "hydro"? Hydro stems from the Greek word that literally translated to water - hydor. If Hydroculture comes from the Greek word for water, why not just call it waterculture? Turns out water derives from old English and with new words, especially new science-based techniques like hydroculture and hydroponics, Latin is usually the root of choice. But that still doesn't explain why Hydroculture isn't called aquaculture..
Interesting fact - the word "hydroponics" first appeared in 1937
We already discussed "culture" above, so we can assume a similar definition -- the act of tilling the land. Looking into the root for "aqua" makes things interesting. In Latin, the root aqua can be translated as "water; the sea; rain." Still in the same vein of water, but now the sea is involved. Aqua's got a couple of German cognates too. One in Proto-German, akhwo and then Gothic, ahua; both meaning "river waters." So while both hydro and aqua both share the same basic definition - water - aqua has a connotation of natural water in rivers and the ocean. With much of aquaculture occurring in pre-existing bodies of water, this makes a lot of sense.
The word aquaculture outdates hydroponics as it first came about in 1869.
There you have it - even though their base definitions are the same, hydro and aqua have different connotations. Hydro is more general, meaning water, and can be found in other words like hydropower, hydrolysis, and hydroplane. Aqua also means water, but is based on root words that share meaning with natural bodies like rivers and the sea. You'll see it in aquarium, aquamarine (meaning color of the sea), and aquatic (growing in water). Because, especially when it was first established, aquaculture was practiced largely in natural bodies of water, even though it had the choice of calling itself hydro-culture, as hydroculture was not yet established, the originators of the word chose aqua and the rest is history.
Top image - http://www.eneserv.com/images/questionmark.png
Passive Hydroculture - http://2.bp.blogspot.com/_EY8igqnU6lQ/TI6YClgLpKI/AAAAAAAAADs/T8hX8mT-67s/s1600/hydroculture-dry.jpg