Photos from the Great Barrier Reef (high bandwidth)
- Thread starter vol_reefer
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SeaHorseTim
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wow.. simply amazing. You've got one outstanding tank there.. what kind of lighting do you use?
Seriously though, well done. It was interesting to see your photo style change from one dive to the next. Thanks for taking the time to give these to us!
Seriously though, well done. It was interesting to see your photo style change from one dive to the next. Thanks for taking the time to give these to us!
vol_reefer
New member
Sorry for the delayed reply - busy day yesterday...
H@rry: I didn't see any obvious bleaching or other reef damage in the water. I'm not surprised, though - dive operators make their money taking you to the nicest spots, not the ones in decline. I'm a little more surprised I didn't see any damage from the flight either, but I'm not confident I would be able to spot it from the air if it was there.
One of the reasons I attended the conference was to learn about remote sensing of reefs - it's an area of research I'm thinking about getting into (my bread-and-butter research work mostly deals with Mars remote sensing). The speakers at this conference were not so much focused on direct monitoring of the spectral properties of corals, but rather on monitoring of water conditions considered risky to corals - things like thermal infrared imaging to monitor water temperatures.
One interesting thingI learned that might have applications to our husbandry of corals: Corals start to bleach when their symbiotic zooxanthellae become saturated with photons - they have a limit to how much light they can absorb through photosynthesis, and any excess photon energy has to be rejected somehow. Beyond this limit, the corals start to bleach. However, this limit on how much light they can photosynthesize is actually strongly dependent on water temperature - the higher the temperature, the lower the limit, by a lot, on how many photons can be photosynthesized. This is why these researchers are so interested in being able to monitor water temperatures with satellites - higher water temperatures (from global warming or any other reason)mean the zooxanthellae cannot photosynthesize as much light. So even though the amount of sunlight stays the same, the corals are more prone to bleaching when the water warms.
The thing I was thinking might have applications for us has to do with an experience I had a couple months ago when I switched out my 14K 400W Hamiltons for 20K 400W HQI Radiums. The PPFD (useful intensity of light) on the new bulbs went up by around 50%. I don't have any way to raise or lower my light fixtures, and I was worried about too much heat being generated in the canopy if I put some kind of window screen material between the bulbs and the water like some people do when they acclimate to new lights. So basically, I just took a hit and let a couple of my corals directly under the lights bleach out. But had I known about this very strong dependence on temperature for how much light the zooxanthellae can take up, I might have tried lowering my water temperature a couple degrees at the same time I installed the new lights. From what I was hearing at the conference, I think there's a decent chance that might have kept those corals from bleaching.
I just hijacked my own thread, didn't I?
Tim: That tank uses a 5800K, 1400W/m^2 hydrogen-powered fusion bulb. If you go that route on your tank, make sure to give the bulb plenty of clearance above your water surface - they tend to get hot.
I'm flattered that you think I have the photo skills to actually have a "style" to change from dive to dive, but I think that's probably being generous. There were some differences from dive to dive just because of varying depths (harder to get reds in the photos the deeper you go) and because I switched between using my own camera to using one provided by the dive operator, and then back to my own. The dive operator's camera actually had 20% more megapixels, but I think my camera did a better job with white balance, exposure, and image stabilization. Plus I was more familiar with its operation, which is a big deal when you have limited underwater time.
Jeff (vol_reefer)
H@rry: I didn't see any obvious bleaching or other reef damage in the water. I'm not surprised, though - dive operators make their money taking you to the nicest spots, not the ones in decline. I'm a little more surprised I didn't see any damage from the flight either, but I'm not confident I would be able to spot it from the air if it was there.
One of the reasons I attended the conference was to learn about remote sensing of reefs - it's an area of research I'm thinking about getting into (my bread-and-butter research work mostly deals with Mars remote sensing). The speakers at this conference were not so much focused on direct monitoring of the spectral properties of corals, but rather on monitoring of water conditions considered risky to corals - things like thermal infrared imaging to monitor water temperatures.
One interesting thingI learned that might have applications to our husbandry of corals: Corals start to bleach when their symbiotic zooxanthellae become saturated with photons - they have a limit to how much light they can absorb through photosynthesis, and any excess photon energy has to be rejected somehow. Beyond this limit, the corals start to bleach. However, this limit on how much light they can photosynthesize is actually strongly dependent on water temperature - the higher the temperature, the lower the limit, by a lot, on how many photons can be photosynthesized. This is why these researchers are so interested in being able to monitor water temperatures with satellites - higher water temperatures (from global warming or any other reason)mean the zooxanthellae cannot photosynthesize as much light. So even though the amount of sunlight stays the same, the corals are more prone to bleaching when the water warms.
The thing I was thinking might have applications for us has to do with an experience I had a couple months ago when I switched out my 14K 400W Hamiltons for 20K 400W HQI Radiums. The PPFD (useful intensity of light) on the new bulbs went up by around 50%. I don't have any way to raise or lower my light fixtures, and I was worried about too much heat being generated in the canopy if I put some kind of window screen material between the bulbs and the water like some people do when they acclimate to new lights. So basically, I just took a hit and let a couple of my corals directly under the lights bleach out. But had I known about this very strong dependence on temperature for how much light the zooxanthellae can take up, I might have tried lowering my water temperature a couple degrees at the same time I installed the new lights. From what I was hearing at the conference, I think there's a decent chance that might have kept those corals from bleaching.
I just hijacked my own thread, didn't I?
Tim: That tank uses a 5800K, 1400W/m^2 hydrogen-powered fusion bulb. If you go that route on your tank, make sure to give the bulb plenty of clearance above your water surface - they tend to get hot.
I'm flattered that you think I have the photo skills to actually have a "style" to change from dive to dive, but I think that's probably being generous. There were some differences from dive to dive just because of varying depths (harder to get reds in the photos the deeper you go) and because I switched between using my own camera to using one provided by the dive operator, and then back to my own. The dive operator's camera actually had 20% more megapixels, but I think my camera did a better job with white balance, exposure, and image stabilization. Plus I was more familiar with its operation, which is a big deal when you have limited underwater time.
Jeff (vol_reefer)
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