Hydroponics is reborn and weddell seals are proved to be more than just adorable animals.

Hydroponics has its yearly clean-up

At Mawson we are lucky enough to have a hydroponics building to grow fresh fruit and vegetables throughout the year. Once everything is happy and growing, the system only requires minor daily maintenance, but at least once a year the whole arrangement needs to be torn down and cleansed. This year we walked into a hydro setup that was full of plants producing at their peak.

Since taking over we have harvested:

  • 7050 g of bok and pak choy
  • 2160 g of snow peas
  • 2810 g of rocket
  • 460 g of lettuce
  • 4130 g of ripe tomatoes
  • 410 g of butter beans
  • 280 g of parsley
  • 190 g of dil
  • 20 g of chives
  • 150 g of chard
  • 380 g of basil
  • 30 g oregano
  • 3830 g of green tomatoes

That’s 22 kg of produce in four weeks! Unfortunately all good things must come to an end. Rather than let the existing crop run its course we decided to get the 12 month clean-out over and done with to avoid having it fall due during the middle of winter.

So, on Friday the thirteenth, we tore it all down. I had already harvested the majority of the useful produce in anticipation of the clean-out, but held out until the very last day to take the tomato plants down in the (unfulfilled) hope that they would ripen. The first step on Friday morning was to remove all the greenery to dry for improved incineration. Once it was all extracted from the building, all the portable equipment was dragged out and down to the dieso’s workshop to be pressure washed, and scrubbed, with a mild bleach solution. Everything remaining inside the hydro building, including the walls, was also bleached. 

Late on Saturday, I planted the first seeds of our new crop — lettuces, rocket, spinach, snow peas, cucumbers, tomatoes, basil, coriander, mint, parsley — and have just seen them starting to germinate.

The next steps are to rebuild the plumbing puzzle inside. Watch this space!

Weddell seals of Mawson

Here is a bit of interesting information about the diving specialities of the Weddell seal taken from one of the books in the library here at Mawson (Seals and Sea Lions of the World, Nigel Banner, 1994).

  • To reduce buoyancy and therefore save energy, they exhale before descent.
  • They have twice the volume of blood per kilogram of body weight than humans and their blood contains about 1.6 times more haemoglobin than us.
  • The combined result of the above is that the seals blood can store up to 3.5 times the oxygen we can.
  • A Weddell seal’s dive can last for up to 73 minutes.
  • When they make long dives their heart rate slows and blood is circulated through the heart, brain and lungs only. Blood flow to the muscles and other organs is reduced by 90%.
  • A dive lasting 45 minutes requires a recovery time around 105 minutes.
  • They often feed on the seabed at depths of 400–600 metres.
  • Seals have a system of blood vessels within the middle ear that fills with blood as they dive deeper to prevent the walls of the middle ear collapsing due to pressure.
  • Unlike humans they don’t have nasal sinuses.
  • A small amount of air is retained in the lungs and windpipe so they can produce underwater vocalisations.

They may look a little awkward out of the water but they are specialist divers, well adapted to their life in the water.

The photos below were taken with either a Nikon D300 or D800 with a Nikon 80–400 or Sigma 50–500 zoom lens to get the close-up shots.