Indian Ocean - too warm?

[jeff99]

Hi everyone

Have posted this on another forum as well. Bit concerned and would like some feedback if possible.

Just got back (two weeks ago) from a trip to the Maldives. Did 21 dives and used my new computer for the first time. Since I got back and downloaded my profiles I noticed that the recorded temperatures seem to be a bit on the high side. The lowest I recorded was 29 deg C at depth. ( That was just on one dive - all the others were 30 deg C ) Surface temperatures were from 30-32 deg C, same as the air temp. I did think at the time that the water seemed to be as warm as it did in 1998, but not having been there in late April-early May before I have nothing to compare it to.

Am I right in thinking that at and above 29 deg C the coral starts to expel its' symbiote? Does anyone have any idea whether this is so or am I being a bit paranoid? The other thing I suppose, is that the computer could be faulty, but both myself and my GF thought that the water did seem to be rather warm. ( We were there in November 2005 ) Hope I'm wrong.

Jeff

[Steve Sub]

Originally Posted by jeff99

Hi everyone

Have posted this on another forum as well. Bit concerned and would like some feedback if possible.

Just got back (two weeks ago) from a trip to the Maldives. Did 21 dives and used my new computer for the first time. Since I got back and downloaded my profiles I noticed that the recorded temperatures seem to be a bit on the high side. The lowest I recorded was 29 deg C at depth. ( That was just on one dive - all the others were 30 deg C ) Surface temperatures were from 30-32 deg C, same as the air temp. I did think at the time that the water seemed to be as warm as it did in 1998, but not having been there in late April-early May before I have nothing to compare it to.

Am I right in thinking that at and above 29 deg C the coral starts to expel its' symbiote? Does anyone have any idea whether this is so or am I being a bit paranoid? The other thing I suppose, is that the computer could be faulty, but both myself and my GF thought that the water did seem to be rather warm. ( We were there in November 2005 ) Hope I'm wrong.

Jeff

I did a 2 week liveaboard there last year (February), and the temps were between 28 and 30 (from memory). IIRC, bleaching can occur when the temp hits 31-32, so it would appear, if your computer was reading accurately, that it's getting very close to that level. I haven't heard about any El Nino event, and besides I believe this is the wrong time of year.
Anybody know more?
Steve

[Richard Mason]

Originally Posted by jeff99

Hi everyone

Have posted this on another forum as well. Bit concerned and would like some feedback if possible.

Just got back (two weeks ago) from a trip to the Maldives. Did 21 dives and used my new computer for the first time. Since I got back and downloaded my profiles I noticed that the recorded temperatures seem to be a bit on the high side. The lowest I recorded was 29 deg C at depth. ( That was just on one dive - all the others were 30 deg C ) Surface temperatures were from 30-32 deg C, same as the air temp. I did think at the time that the water seemed to be as warm as it did in 1998, but not having been there in late April-early May before I have nothing to compare it to.

Am I right in thinking that at and above 29 deg C the coral starts to expel its' symbiote? Does anyone have any idea whether this is so or am I being a bit paranoid? The other thing I suppose, is that the computer could be faulty, but both myself and my GF thought that the water did seem to be rather warm. ( We were there in November 2005 ) Hope I'm wrong.

Jeff

Question to ponder - how accurate is the thermometer in your computer?

I don't have a thermometer in my puter, it's just a bog standard Aladin Pro, which suits my kind of diving, however, amongst those that do, I've noticed some fairly wide variations in temperatures displayed between different computers.

Richard

[bob wippin]

You have to remember that the temp sensor may be on the back of the computer. This means you will be keeping it nice and warm with your arm, especially if you are wearing a wetsuit with the computer done up nice and tight allowing little water movement.

You were warm in the Maldives? I was getting a bit cold with approx 5mm wetsuit on body, in some of the stronger currents on the outer reefs, about a month ago.

Where did you stay in the Maldives? Obviously the water temp varies with depth and if you are in the innner reefs the water temp will be a bit warmer than if you are on the exposed ocean sides. I know in North Male atoll they have had big problems with coral bleaching in the past. But am not sure on the exact temperature the coral bleaches at so cannot help you on this. Regarding your computer I would not be too worried about it, the temperatures seem fine to me.

[dry suit diver]

Originally Posted by Richard Mason

Question to ponder - how accurate is the thermometer in your computer?

I don't have a thermometer in my puter, it's just a bog standard Aladin Pro, which suits my kind of diving, however, amongst those that do, I've noticed some fairly wide variations in temperatures displayed between different computers.

Richard

aladin pro does have a temp reading but is only accesible on download to a PC.

I think it may be as a previous poster says with the wetsuit etc keeping it at an elevated temp. I too have not noticed any reports of an el nino effect type event.

[jeff99]

Hi everyone - thanks for responding.

Don't think there's an El Nino this year - thought it was an El Nina (cooling) in the Pacific, so don't think it's got anything to do with this specifically, but it did seem to be v warm. ( This was just snorkelling with shorts, but on the reef, not in the lagoon, which can be very warm anyway due to the strong sun on the shallow water.) I was in N. Male Atoll, but dived on the outer reefs as well and that was where the lowest temperatures were. I was in a 5mm. too and have to say I was very toasty - so was my GF, using a 5.5, and she is ALWAYS cold! Have been to Maldives 6 times in total, and the only other time I thought it was v warm was in 1998, which is what got me to thinking........hope I'm wrong.

As regards the computer accuracy and the effects of the wetsuit, I did wear it rather loosely to ensure the sensors were exposed to the water, but it is possible it isn't accurate although it was brand new - a Vyper. It did record the air temperature accurately as far as I can tell, recording between 30 and 34 when worn prior to the dives. Dived at Manta point on one day - the one near Male on the outer reef - strongish current running - to 21.6m. The surface temperature recorded was 30 and the bottom temperature was 29. This seems to be too high to me for the open ocean where the effects of upwelling, currents and wind are to a degree cooling off the shallower, calmer water found in and around the inner atolls. Again, hope I'm wrong.

Bit of a funny story - we had been on the island for 10 days or so and had become very acclimatised to the heat. ( There was no aircon in our room.) We used to get up early every day to see the dawn, walk around the island etc. We always saw Dian the barman on our early morning strolls and he would always say" it's very hot today", go across to the thermometer he kept at the back of the bar and tell us "it's 31" or "it's 30" etc. This particular day we awoke to find that it was cloudy and windy and noticeably cooler. So much so that I had to put on a fleece and my GF had to put on her one and only Gatwick jumper due to the goose pimples that had suddenly appeared on her arms. Walking along to breakfast, we went past the bar and said "Hello" to Dian the barman who said to us " It's very cold today" in the same manner that he usually said " It's very hot today". As usual after remarking upon the temperature, he walked across to the thermometer and said " Yes it's 29"

Jeff

[rooster]

Hi Jeff

Recent evidence that I have read (that I cannot find a link to now) suggests that different coral zooxanthellae will depart at different temperatures so some coral is more resilient to higher temperatures than others.

29-30 degrees does not necessarily seem too high in any case - my 3 months of diving in Central America was all done at 29-31 degree range. Bleaching had occured during el nino but am not aware that it was a continual problem at 29 degrees in this part of the world.

If you google it I am sure you can find more information. Alternatively Dr Stevil will be along soon to correct all my errors and misinformation........


Regards




Roy

[NeilB]

I think your temp guage is quite accurate. We are a little up the coast in Oman and the water temp has reached 28 - 29 degC at the surface. It does get to 32 degC in the mid summer heat. Temps at 25 - 35m are still in the 24 degC range.