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Old 22-02-2009, 21:13   #76
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Here's the problem:

These scientists thought there might be a problem - that is, sunscreen killing corals. So, they then proceeded to kill corals with sunscreen. It's that simple. Unfortunately, in the study we DIDN'T see:

ANYTHING related to measuring the sunscreen in seawater at often visited coral reefs.

How tough could THAT be. Take a snorkling trip from a cruise ship. That's an insanely critical piece of research that is REQUIRED to prove this hypothesis. I don't CARE if the National Geographic published it or not - it's tragically flawed science. While some have pointed out that the study didn't SAY sunscreens were killing coral, they put all of the pieces together so that a reader would infer exactly that. Then the story was repeated all over the world, and it is now considered FACT. And it's NOT. The "researchers" knew that would happen, and that's why they did it.

Jerry, you say: " The posters who are skeptical because of the dilution effect raise a very legitimate question." Yet you agree with the conclusions of the study! My 10th grade Biology Teacher would have given me a "C" on this research. Seriously.

Coral bleaching is VERY SIMPLE: YOU PISS OFF THE CORAL TO THE POINT THEY EXPELL THEIR ZOOANTHELA. It's just so very easy to do. In high/low enough concentrations, ALL of the following will do it: Fresh water. Water that is too salty. Too much sunlight. Too little sunlight. Urine. Gasoline, diesel, too much phosphate, too little calcium, too little magnesium, too much ammonia (from decaying matter), too much nitrite, nitrate... blah, blah, blah. You get the point.
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Old 22-02-2009, 21:22   #77
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Gord:

FROM NATIONAL GEOGRAPHIC:

"Swimmers' Sunscreen Killing Off Coral":

Swimmers' Sunscreen Killing Off Coral

Sure seems to me that the prestigious National Geographic seems to be saying 1 plus 1 equals 3! I'd bet that this is EXACTLY what the publishers had in mind...
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Old 26-02-2009, 19:05   #78
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Quote:
Originally Posted by GordMay View Post
"... Different sunscreen brands, protective factors, and concentrations were compared, and all treatments caused bleaching of hard corals ...
Among the ingredients tested, butylparaben, ethylhexylmethoxycinnamate,
benzophenone-3 and 4-methylbenzylidene camphor caused complete bleaching even at very low concentrations(parabens accounts for 0.5% of sunscreen ingredients). Conversely, all other compounds tested (i.e., octocrylene, ethylhexylsalicylate,
and 4-tert-butyl-4-methoxydibenzoylmethane)and the solvent propylene glycol, which is also present in sunscreen formulations, had a minor effect or no effects when compared with controls.
These results suggest that sunscreens containing parabens, cinnamates, benzophenones, and camphor derivatives can contribute to hard-coral bleaching if released into natural systems..."

The authors made no such claim that sunscreen is wiping out the world's coral.
Gord, I have to take issue with your last statement. In the original article the authors made the following statement.

"According to these estimates, we believe
that up to 10% of the world’s coral reefs
would be threatened by sunscreen-induced
coral bleaching."

The authors did not present any evidence to support this conclusion. The authors present no data on the lifetime of these compounds in a natural environment. While their results are well supported given the limits of the study, their conclusions about the impact or potential impact are not supported at all. It's becoming a more common practice today to mix the results and discussion sections of scientific papers such as has been done here, thus blurring the line between the two. This is a pet pieve of mine which belongs in a scientific forum, not a cruisers forum so I'll let it go. I'll stand by my earlier post that this paper presents interesting preliminary results that warrant further research, but it does not support the conclusion that any coral reefs are threatened by sunscreen, let alone 10%.

Also to the point about the sunscreen slathered bather coming in contact with the reef. My guess (and only a guess) is that the coral would see it as an irritant and generate slime to remove it. It would also likely leave the bather with an infection prone scratch (paybacks?). I however make no conclusions without adequate controlled experiments to back them up. In the meantime I would discourage people from making physical contact with coral reefs as much as possible.

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Old 26-02-2009, 22:28   #79
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I wear a full length stinger suit. It may not look sexy but it doesn't require sunscreen and I am protected form some very painful jellyfish stings. I feel that people should at least wear a long sleeved rash shirt for protection and this would reduce the quantity of sunscreen into the water. There is the potential for the sunscreen to collect on the surface of the water and then when the tide drops, the concentrations would be much higher than the simple dilution factor would indicate. The surface of the ocean is not simply H2O with various ions dissolved but actually has a structure built up from the critters in the water and could possibly induce some method of concentrating the chemicals . Agreed the study needs follow up to determine if the concentrations in the real world can cause problems but it is a bit simplistic to dismiss the study out of hand based on the dilution factor, though I would take it with a grain of salt.

I worked on coral bleacing, studying the changes in the photosynthetic capability of the zooxanthellae. My understanding of the problems of coral reefs are illegal fishing practices such as cyanide and dynamite, mining for coral, anchors, effluent runoff, and acidification of the ocean from CO2 increases weakening the structureof the coral. Global warming by itself theoretically should change the particular species in an area rather than long term wipe out the reefs, and all of these others could be reduced with education of local populations, except for the acidification. This poses a much greater danger than the sunscreen. There may be more tourist damage done by the extra CO2 from the transport to these places than the sunscreen. If we really want to protect the reefs, we need to somehow get the CO2 concentrations down.

This acidification effect is simple high school chemistry and has been well tested. Google acidification and coral reefs and you should find plenty of studies.
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Old 26-02-2009, 23:27   #80
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Robert, You make some very good points. I always wear a long sleeve dark t-shirt at the very minimum. From a cruisers point of view there are a lot of things we do that put coral reefs at more risk than sunscreen. A poorly placed or dragging anchor, running aground, fuel and lubrication oil leaks, holding tank discharges, grey water discharges, etc are all known reef health issues at least if they are done in the wrong place. I suspect but do not know however that the amount of CO2 contributed to the atmossphere by tourist travel is probably miniscule when compared to industrial and other transportation contributions. One might expect more of a local effect from cooling water">engine cooling water since the CO2 is placed in direct contact with seawater in the exhaust of most vessels. One of these days I'll have to check the PH of my diesel exhaust water. In the meantime I'll keep the sails up and the dieseling to a minimum.
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Old 09-03-2009, 04:56   #81
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volume of oceans = 1.37 x 10^9 km^3

dilution factor = 10/10^6 = 1/10^5

vol of sunblock needed: 1.37 x 10^9 / 1 x 10^5 = 1.37 x 10^4 km^3

vol of 1 bottle of sunscreen = 375ml = 3.75 x 10^-4 m^3 = 3.75 x 10^-13 km^3

no. of bottles needed to achieve dilution: 1.37 x 10^4 / 3.75 x 10^-13 = 3.6 x 10^16 or 36 thousand trillion bottles of sunblock (which does seem like rather a lot )

maybe someone could check my calc
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Old 09-03-2009, 05:00   #82
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Quote:
Originally Posted by bobsadler View Post
volume of oceans = 1.37 x 10^9 km^3

dilution factor = 10/10^6 = 1/10^5

vol of sunblock needed: 1.37 x 10^9 / 1 x 10^5 = 1.37 x 10^4 km^3

vol of 1 bottle of sunscreen = 375ml = 3.75 x 10^-4 m^3 = 3.75 x 10^-13 km^3

no. of bottles needed to achieve dilution: 1.37 x 10^4 / 3.75 x 10^-13 = 3.6 x 10^16 or 36 thousand trillion bottles of sunblock (which does seem like rather a lot )

maybe someone could check my calc
You are assuming even dilution. How about reading my comments earlier on the possibilities of concentrating materials in certain circumstances. Surely you have seen slicks at sea in tide lines
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Old 10-03-2009, 02:02   #83
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i guess when you're busy saving the planet there's no time for humour
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Old 10-03-2009, 08:23   #84
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I have noticed that National geographic and perhaps some of the people on this forum equate coral bleaching (expulsion of zooxanthelli) with coral death. They are not the same thing. Bleached corals are not dead corals, though dead corals and bleached corals look similar to the casual observer. Corals can and do recover from bleaching. I had a problem with water quality in one of my aquariums and a couple of pieces of coral bleached. We corrected the water quality problem and in a few weeks the corals were back to their normal colorful selves.
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Old 10-03-2009, 10:57   #85
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Corals can develop new symbiotic relationships with algae from their environments after they’ve undergone bleaching, the process by which corals whiten as a result of environmental stress.

Every coral species, as well as numerous other reef inhabitants, maintains a special symbiotic relationship with a microscopic organism (algae) called zooxanthallae. Healthy Coral Reef These organisms provide their hosts with oxygen and a portion of the organic compounds they produce through photosynthesis. When stressed, many reef inhabitants have been observed to expel their zooxanthallae en masse. The polyps of the coral are left bereft of pigmentation and appear nearly transparent on the animal's white skeleton. This phenomenon is normally referred to as coral bleaching.

More severe bleaching events have dramatic long-term effects on the coral. The ability of the coral to feed itself in the absence of zooxanthallae may be very important to its survival during and after a bleaching event. Recovery rates appear to differ, however, with species, and the time required to attain full recovery of symbiotic algae may vary from as little as 2 months to as much as one year. When the level of environmental stress is high and sustained the coral may die.

Long-term recovery of reefs from bleaching requires local action to increase resilience
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Old 10-03-2009, 21:07   #86
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Captain Bill:

It IS amazing to see what happens in your LIVING ROOM, and then compare it to what others try and stuff down the public's throat. Corals are so cool - they CAN'T move like fish - they tend to be very adaptive.

For those that MIGHT be interested, here are some pix of the reef in my living room (please spare me the carp about collectors - my fish and corals are almost all either aquacultured by others, or rescues):

reefin streep style - MAAST Forums
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Old 10-03-2009, 21:39   #87
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Wow Bill. Possibly the nicest seawater tank I've ever seen. I had a 130 gallon fresh water tank once with Discus, and always wanted to move up to Saltwater then I moved across the country and we couldn't take the tank with us.

What's your secret? No wait, I know, sunblock lotion right?
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Old 11-03-2009, 00:42   #88
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Captain Bill:

It IS amazing to see what happens in your LIVING ROOM, and then compare it to what others try and stuff down the public's throat. Corals are so cool - they CAN'T move like fish - they tend to be very adaptive.

For those that MIGHT be interested, here are some pix of the reef in my living room (please spare me the carp about collectors - my fish and corals are almost all either aquacultured by others, or rescues):

reefin streep style - MAAST Forums
Sometimes the corals can have quite a few different symbiotic algae inside them. If there is some around with the right temperature characteristics and can smile the right way, the coral can quickly take them up and they can start again fairly quickly. If the conditions are not right, the coral can die. Providing there is no other pressure on them they tend to recover reasonably well with a greater tolerance to higher temperature, but may have less tolerance to lower temperature. If there are other pressures on them, it may be the last straw.
I am impressed with your tank. It is not easy to keep these things in balance. The relatively high density of fish in artificial tanks means a close eye on the nitrogen levels and pH.
Maybe you can do an experiment and see if a few drops of sunscreen in the tank has any effect. I don't expect it will, especially as you would have good filters and I wouldn't expect any surface interactions for the coral as you wouldn't have a high and low tide. Unless you wish to deliberately lower the water levels for the experiment and then expose them to light and temperatures of full tropical sun.
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Old 11-03-2009, 17:37   #89
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The secret to a great reef tank is exactly the same as the secret to a great boat:

Throw money at it!

Seriously, it's an expensive hobby, on the scale of a 200g plus tank. The lighting alone runs our electric bill up nearly $100 a month! I've had some corals I've grown that sell for over $50 a branch inch - and NO it's nearly impossible to make money doing this. I've been in the hobby since 1969, when I worked in a store from 8th grade thru college.

I'm not ready to get into the suntan lotion experiment! As for tides - yes, my tank gets a water change every 10 days that exposes the top corals to high intensity lighting for a short period of time. No, they don't like it. They slime like mad.
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Old 13-03-2009, 12:15   #90
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I am NOT jumping in to the science debate here --

but I will be the first in the discussion to say, yes -- I use organic sunscreen. Not because I am worried about the oceans, but because I care about what gets rubbed in to my kid's skin. We use the brand JASON organic, and we're very happy with it. It does the job.

(Schoonerdog's wife, Cindy)
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