[Coral-List] Re: PAR

Jade Maggs jmaggs at seaworld.org.za
Wed Jan 25 05:11:26 EST 2006

So what does it mean if one light source has a higher PAR rating than another, I am assuming that a higher PAR rating is more beneficial to corals. I am trying to make sense of why the corals that are collected at, say, 50 ft need the intense lighting that we try to provide them with. Also what is the essential difference between two 13000 kelvin bulbs if the lumen output is the same. I thought that maybe this is where PAR came in. Maybe one has a higher PAR rating than the other.

Thanks again for any help.
Jade Maggs
uShaka Marine World
083 515 1079
  ----- Original Message ----- 
  From: Jordan Watson 
  To: jmaggs at seaworld.org.za 
  Sent: Wednesday, January 25, 2006 1:13 AM
  Subject: PAR

  Hi Jade.

  I'm no expert on PAR, but I just thought I would throw you a few words.  First, if you are going to search, I have heard it more often referred to as Photosynthetically available radiation - which I have always understood as the fact that the UV range of the EM spectrum is exactly that, a range.  However, just as with the utilization of the visible spectrum by chlorophyll, different wavelengths of the visible spectrum are absorbed by chlorophyll a and b.  PAR is thus the range of "usable" UV that is available or usable from a particular light source.  Two identical lights sources should not vary in the PAR emitted, assuming that their functional range is identical.  

  Not sure if it's helpful, but Maria Vernet has done a bunch of Antarctic research on the uptake of UV by phytoplankton and might give you a better background on the implications for your work.  Sorry I don't have a specific reference as I'm not sure which paper of hers would be best.  She is at Scripps Institution of Oceanography.  http://www.sio.ucsd.edu/rab/act_detail.cfm?state=%26%2B%5E%3B%2AW%2C%2F%5F%0A

  Here's a start.
  Good luck.

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