El Nino and corals
Sea cave ambi
NPR/NGS Radio Expeditions
4 Jun 1998
- Galapagos Islands; Wolf Island
- 1.38611 -91.81972
- Marine Shoreline
- SONY TCD-D10 PRO II
- Sennheiser MKH 30
- Sennheiser MKH 40
Stereo=2: 1=L, 2=R; Decoded MS stereo; Sennheiser MKH40 Cardioid Mid Mic and MKH30 Bidirectional Side Mic into Sony TCD10; Sennheiser MKH40 Cardioid Mid Mic and MKH30 Bidirectional Side Mic through Sonosax Preamp into Sony TCD7
NPR/NGS RADIO EXPEDITIONS - GALAPAGOS LOGS
NPR/NGS - RE - Galapagos
DAT #3 page 1
In the boat going to dive site
01:00 - 05:00 Ambi in small boat - puttering along, cliffs on right, Dolphins beside boat.
07:00 - 08:30 Ambi with motor off - Birds and sea [NVG]
10:00 - 14:10 Ambi - [motor on] Waves + peeps of dolphins at 12:00
@12:40 Mics seem lower off bow to catch ambi of waves, some birds
13:36 - FX - Dolphin?
14:36 - 17:00 Ambi of boat slow down and circling other boats where scientists are swimming and talking
in the water
17:00 - FX - engine off
**18:00 - 18:30 AX: JW: We¿re anchoring here at about 50 feet of water, and we¿re situated over a coral where we think we can get a pretty good core, so right now we¿re setting the anchors at a three point mooring, hopefully we¿ll get something.¿ [+ more chatter re. site by grads and Rob and Jerry]
22:30 - 32;30 - Hydrophones [NG]
Ambi of undersea drilling [not great because signal is in and out, but we will work with it]
33:13 - 37:29 Ambi Drilling above water [PICK just one minute to load]
37:30 - 43:20 - Ambi with hydrophones - with/without drill - [Note: drop outs again [NG]
**43:45 - 47:23 AX AC: What did you get out of that?
RD: This is our first try at drilling corals here at Wenman, so working out some of the kinks in the program, so we drilled two short cores out of a colony of pavona [sp]. That particular coral full of little borings from clams that actually dig into the colony. If enough of those little holes, looks like Swiss
cheeze it makes it very hard to drill, so we drilled in about 40-50 centimenters, and the pieces of core came out in little chunks. So we have about 8 pieces¿Moved over to another colony - drilling down there now
** AC: Can you see effects of El Nino?
RD: If you look down from the surface here, and we¿re 50 feet off the bottom, see this mixture of brown and white circles on this black bottom, and those circles are all corals, and normally they¿re all brown
and would hardly know there were corals there, would blend in, but this particular site has responded to phenomenon known as coral bleaching, where coral has lost some of pigmented algae, and the tissues remain intact, but the tissues are crystal clear, can see right through them to the white skeleton of the coral. Doesn¿t happen very often and if that condition is maintained very long, then the corals will perish. Jerry was estimating that at this site the bleachings had perhaps been underway for two or three months
and it would seem that if it lasted much longer, would die. So this is certainly a very visible sign of climactic phenomenon.
AC: If look up here - on cliffs - vegetation, very green. Seen this before?
RD: No, this is an exceptionally green year, and one of the interesting features of this phenomenon is that here in the Galapagos, when the ocean gets warm, creatures in the ocean die, but that same warm water causes tremendous rainfall. Been raining here 3-5 times as much as normal¿.cliffs covered with vegetation.
AC: Bird life - looks healthy.
RD: Most of these are seabirds, would expect to show some effect of the diminished productivity of the ocean. On some of the other islands, birds depend on food from the land, and those bird colonies seem to be booming, like the finches on Daphne Major and Minor. Most of these are seabirds¿¿[47:23]
48:43 - 49:05 Ambi, then more motor ambi from interview.
NPR/NGS - RE - Galapagos
DAT #3 - p.2
56:12- 58:00 Chatter with Jerry [NVG]
59:24 - 1:00:00 Ambi - swimmers in water + Alex dive into water
1:02:23 - Ben re. fish - finding fishes, rasses that don¿t usually find here.
[then Jonathan re. plans - off mic + swimmers fooling around in water, blowing, bobbing, chatting]
1:05:25 - 1:05:38 FX Good dive into water. + air valve. Swimmers in water.
*1:06:18 - 1:07:20 FX - Motor start for pump at sea - then more active after 1:07:00
1:10:00 Ambi in cave along cliffs - with birds [G] 1:13:43 Motor/engine start at sea, move off along coast. Then motor along away from cliffs and around end of island [1:14:45] [OK]
1:15:03 - AC and Leo ID scene - in the rain
1:16:16 - 1:20:00 Ambi - rain
1:23:50 - 1:25:35 - Ambi - In cabin - radio, Horn, door slam
1:25:26 FX - Horn from inside
**1:26:29 - 1:26:45 FX - Horn [from outside] + Ambi
Alex and and Rob Dunbar -
RD: I¿m an oceanographer and climatologist from Stanford University. Working on Galapagos for 20 years now. Talk re. difference between ¿weather¿ and ¿climate¿. Interest in climate
AC:Why is coral good for measuring climate?
RD: Corals have been used many ways - to look at climate change. The first story you were referring to was this bath tub ring that forms around some of the islands of the Pacific where in the past when sea level was a little bit higher, the corals grew there, then sea level dropped, and left behind this ring of corals. Story is very clear, this coral that represents a high stand in the ocean, and the reason that
works and the reason corals are so useful is that they only grow in shallow sunlit water, and there are some species that only live within two or three meters of sea level. Because of that they are tremendously useful as sea level indicator. When you find them at great depth in the ocean, it tells you that sea level was lower at the time these corals grew. When you find them emergent out of the water, it¿s a pretty good indication that that area was covered with water, but that sea level right at that exact level. Another way is a chemical, physical approach. The corals are growing their skeleton in a very steady fashion - some of these corals in Galapagos grow 1-2 centimeters a year, and as they grow, they form rings - very similar to rings you see in trees - so when cut the corals and examine these bands, can count them from top to bottom and develop a simple chronology¿.then go back and sample these bands individually. And this coral skeletal material holds many, many components that tell us what water temperature was, possibly the amount of sunlight available, the amount of nutrient exchanges ocean circulates vetically in this part of the world¿¿¿.so it¿s this combination of confinement to the uppermost part of the ocean, and the ability of the coral skeleton to incorporate many climate signals that makes them very popular for those of us who are studying the past climates of the tropics.
NPR/NGS - RE - Galapagos
DAT #3 - p. 3
AC: What happens to the coral in an El Nino year? Last El Nino - 82-83¿.can go back hundreds of yers, you can see that that¿s the biggest ¿.
RD: [1:35:26] We noticed that in a number of areas in the Galapagos number of corals suffer during the El Nino events. Something related to increased temperature in the ocean, greater susceptibility to disease.
Significant coral mortality. And in fact in a few of these islands, during the 82-83 event, 95% of the corals
perished. When the corals die, their skeletons can be immediately colonized by some other organisms¿.
¿¿can usually see when drill down through 82-83 event, will show up as a dead zone¿unique in last 200 years, maybe last 400 years. Led us to speculate that 82 - 83 very unique..
AC: Would this year be similar?
RD: Verdict not in. As saw yesterday just around the corner, were large colonies of corals - bleached. If that continues corals will die, but they¿re not dead yet. And there is a chance the recovery will occur rapidly enough¿will find out more in coming week¿..
AC: Interested to learn from Jerry if go back and look at the record, the coral has only been established here for 5-600 years,
RD: Would be surprised if corals had not been here for last 5-6,000 years¿¿
1:39:16 Problem here in Galapagos is that so many organisms in the ocean that colonize the coral colonies, and after they die, and erode them so they fall apart, we don¿t see many older reefs¿.
If go to Australia, find healthy community of living corals, living on top of old skeletons¿system of large reef framework that has developed over many thousands of years. ¿¿here in Galapagos, we don¿t see any reef frameworks, this is an area of coral communities, not coral reefs¿[Alex, note for script]¿¿and the isolated coral colonies that make us these communities when they die, they tend to be broken apart¿
perhaps in a few decades, then the remains are gone. So that¿s why it¿s very difficult to look at the modern record today, here in Galapagos and try to understand when corals first appeared because those first recruits no longer here¿¿
AC: so you go looking for biggest head, clump of coral¿..
RD: This is a fringe setting for corals. The water can get very cool curng anti-El Nino times, and then
during El Nino, large amounts of mortality can occur, so it¿s a rough place for corals to make a living. You find many small colonies, few large¿.diff from Caribbean or Australia¿¿
AC: Why would that be. We¿re here on the Equator¿..
RD: This is a special part of the equator where cold waters arriving from polar regions and also from cold water right below the surface. We¿re tucked up here against the west coast of South America¿.there¿s a very cold current called the Humbolt current or Peru current that¿s moving up north along the coast of S. America, tapping into feedstock pool of cold water that circulates around Antarctica, so even though the water¿s coming up from high southern latitudes a long distance, it¿s coming up fast enough so retains that cold signature of the southern ocean, so that¿s one of the factors that contributes to the cooling.
Second factor is that right here on the equator a special kind of upwelling can occur - where the water is moving away from the equator on both sides. Water moving to the north - some surface water to the south, water is replaced at the surface by upwelling¿.can cool local waters¿..and the corals that live here
corals suffer at temperatures that live below 23 or 24 degrees.
AC: Peculiar to me that have islands on equator with penguin colonies¿..more re. penguins¿..
AC: Do climatologists understand the source of El Nino¿..where is the pattern coming from
RD: Classic chicken and egg question¿..in last few years, people decided question not all that interesting. What looking at now is ocean and atmosphere together as a coupled system¿.the wind is driving the ocean, and the ocean is driving the winds, and it¿s not so important to understand which came first for particular El Nino event. In this case, the warm water that is impacting the Galapagos, some of that water
NPR/NGS - RE - Galapagos -
DAT #3 - p. 4
did indeed start out in the western Pacific, and propagated eastward across the Equator. But what initiated that is up in the air¿..could have been tradewinds¿¿what would change the winds¿.its the ocean¿.and it seems as though different El Ninos can be started by different combinations¿.
[1:]46:15 Every El Nino is different¿¿many different flavors of El Nino¿..all initiated by
a coupled ocean/atmosphere phenomena - that the coupling may be different for each event¿..
AC: You look back the coral record in the Galapagos, you can find how different El Ninos have occurred over 4-500 years.
RD: [1:47:37] Yes, we go back about 400 years¿..The pattern shows El Ninos occurring through the entire period of the last four centuries, always a phenomena impacting these islands, but the biggest changes seem to be in frequency, the return period of large events. For example, the corals tell us that in the 1600s large El Ninos occurred every 6-8 years¿whereas today we see El Ninos occurring about every 3-1/2-4 years¿.so one of the things that corals suggest is that the frequency of El Nino has changed over a century time scale¿.. also looks as though these changes occurred fairly abruptly, that is there were century long periods that were characterized by an El Nino every six years. Then a century where occurred every 4 years.
AC: People wonder if we are doing to the climate.
RD: Yes, good point. Corals have skeletal records that extend back prior to the time that man induced forcing was important¿..the records here go back 400 years¿..man-induced forcing not important¿
¿..the fact that we see sudden shifts¿.. in mid 1700s climate system has ability to jump¿..from one mode to a completely diff style based on natural transition, not anthropogenic¿why some of us looking at north Pacific¿.
AC: saying we don¿t need to worry re. man¿s effect on global warming¿..not that global warming and el nino are the same. [1:51:51]
RD: Yes, can separate that out¿. One is that the climate system, natural variability. But superimposed over that is a trend towards warmer climates over the last century, and certainly good possibility that warming related to human activity¿..verdict not in re. magnitude.
Very good possibility that man¿s activities are contributing in a fairly significant way to the warming in last 80-90 years. [1:53:15]
+ Radio transmission with Jerry re. problems with drill
Ambi from interview with Rob Dunbar: 1:57:10 - 1:57:40
+ more radio