Several months ago at lunch we gave ourselves a challenge: “Could we turn one of the new wet labs into a compact shellfish hatchery that could be used for our Olympia Oyster restoration efforts and produce significant numbers of shellfish seed for commercial research?”. More importantly could we take lessons from the building systems and make the hatchery as energy efficient as possible?
After a lot of hard work by the team, this week our new “compact hatchery” really came on line. This is what it looks like from the public viewing mezzanine. Read on for a long geeky shellfish explanation of what we are up to and some shots of us spawning geoducks which is pretty crazy in itself.
Last year we built a pilot “mini-hatchery” that used ambient summer water temperatures to grow seed of Native Olympia Oyster (Ostrea Lurida) for our restoration efforts. It was small and worked well, but to do better we needed to be able to temper (read heat) our seawater. Here’s a photo of Sarah Leduc with last years self contained Oly oyster mini hatchery.
Shellfish hatcheries are tricky things – most of the time and energy is actually spent maintaining pure cultures of phytoplankton that you use for feed. Growing high quality phytoplankton is much an art as skill and we have some great homegrown phytoplankton culture talent from our Fisheries and Aquaculture Program.
F&A alumni Sarah Leduc (above) with assistance from practicum students like Shannon Barrett, is now maintaining cultures of four species of marine phytoplankton in very small sterile cultures. Working starter cultures are shown here:
These cycle from 1 litre flasks to 4 litre flasks to 20 litre carboys and then finally bag cultures that can exceed 10 million cells per milliliter and as high as 20 Million cells/ml. This all provides nutritious food to broodstock, larvae and seed.
The other tricky thing and usually most expensive, is heating seawater efficiently. Shellfish larvae are reared in seawater from 12 degrees to over 24 degrees depending on the species and heating water is a major cost to commercial hatcheries. We couldn’t afford a dedicated seawater boiler but we have a building full of geo-exchange heat, so after lots of lunch time doodling on our whiteboard, we tapped into our building heating system to heat our culture water.
But first, we did a couple important things to increase efficiency – first we co-located our larvae cultures in the same room as the algal cultures. The lights we need to grow algae kick off excess heat – (so much so that we have to cool the bags with drip irrigation emitters). This heat keeps the room warm and we don’t have to worry about losing larvae water heat to cooling. Secondly we installed a recycled surplus titanium heat exchanger (salvaged from a crab plant that was refitting) so that incoming seawater water flows past discharge water and we can recover (recycle) about 5+ degrees of heat in the system. Warm building heat (geo-exhange) water was then flowed through a second recycled heat exchanger to provide the rest of the heat increase we needed to fully temper the water. We then filter that water down to 1 micron and when necessary sterilize it with UV light.
So in summary…..
… we are recycling heat from lighting, recycling heat from water that is leaving the lab and most importantly using efficiently produced hot geo-exchange water to heat our larval culture water. The latter is most cool because we first produced hot water by using the thermal mass of all the seawater leaving the Field Station and robbing/compressing that heat through a process called geo-exchange and heat pumps. So in summary (in best Bill Nye voice): we are using a lot of seawater to heat a smaller amount of seawater and then recycling that heat as much as possible. At first, we were confused too – but the white board helped a lot. We think this could be a model for commercial hatcheries, especially as heating costs rise.
Here’s the new hatchery again with some labels:
1. Shelves of 1L, 4L and carboy cultures, for any phytoplankton types – we have all the normal nutritious standby’s going: Chaetoceros calcitrans (diatom) Chatoceros gracilis (diatom), Isochrysis galbana (flagellate) and Rhodomonos salinis (big fat Diatom!). Think of it as a salad bar for shellfish. Thanks NCMA (formerly CCMP) for all our stock cultures.
2. 12 x 350 liter bag cultures packed as tight as we can running as “batch”cultures. This is what we feed from. Hopefully in the future we’ll advance this bank up to continuous culture, but walk before we run eh?
3. In the corner is a tank of Carbon dioxide on a timer to inject into the algae air supply- this is the carbon source for the algae – Phytoplankton take up CO2 and turn it into food, why the oceans are so important for taking up CO2 from the atmosphere. We also have to add vitamins, nutrients and silicates to the cultures.
4. Six previously surplus tanks for larvae – not the fancy white larval hatcheries conicals we want, but good enough for now. We are using these in what is called high-intensity continuous flow culture. This allows us to grow the same number of larvae as a static tank 20x as large – great when we are packing into a very tight space.
5. Up against the wall and mostly hidden from view is the geo-exchange and heat recovery system that we have assembled to heat the larval seawater. This includes hot building water on a loop, 2 recycled titanium tube and coil heat exchangers, cartridge filters and a UV system all tucked tight into the corner.
6. Two banks of upweller/downweller units. These will be used to “set” the larvae at metamorphosis and rear them until they are large enough to go into ambient water (in the next lab over).
Now to use it all…
…. So this summer we will be using our new set-up to rear Native oysters for restoration, produce geoduck seed for production research and investigate methods for commercial production of sea cucumbers. During some late nights this week, we started spawning geoducks.
Here is visiting Brazilian PhD student, aquaculture engineer and hatchery whiz Francisco with two geoduck broodstock, the worlds largest burrowing clam. Humourous to us, because Francisco normally works on culture of a clam that is less than 2 cm. These things are beasts. As an example here is a raw Gopro video of a male geoduck spawning.
Sperm deposited into the mantle cavity is being discharged via the exhalent siphon. Think geoducks just look impressive? – these males will do this for well more than an hour. The females do the same and can have more than 100 million eggs!
As they start spawning we identify them by sex – yep pink ribbon for the girls.
Sieving fertilized egs to remove excess sperm before putting the eggs into larval tanks.
Some handsome looking geoduck broodstock.