Why I still have hope for coral reefs | Kristen Marhaver

84,486 views ・ 2017-08-11

TED


Please double-click on the English subtitles below to play the video.

00:12
The first time I cried underwater
0
12746
2424
00:15
was in 2008,
1
15194
1543
00:16
the island of Curaçao,
2
16761
1577
00:18
way down in the southern Caribbean.
3
18362
1882
00:20
It's beautiful there.
4
20668
1652
00:22
I was studying these corals for my PhD,
5
22344
2926
00:25
and after days and days of diving on the same reef,
6
25294
2382
00:27
I had gotten to know them as individuals.
7
27700
2029
00:29
I had made friends with coral colonies --
8
29753
2471
00:32
totally a normal thing to do.
9
32248
1754
00:35
Then, Hurricane Omar smashed them apart and ripped off their skin,
10
35080
4696
00:39
leaving little bits of wounded tissue that would have a hard time healing,
11
39800
4489
00:44
and big patches of dead skeleton that would get overgrown by algae.
12
44313
3307
00:48
When I saw this damage for the first time,
13
48201
2024
00:50
stretching all the way down the reef,
14
50249
1810
00:52
I sunk onto the sand in my scuba gear
15
52083
1857
00:53
and I cried.
16
53964
1396
00:55
If a coral could die that fast,
17
55384
2357
00:57
how could a reef ever survive?
18
57765
1889
01:00
And why was I making it my job to try to fight for them?
19
60174
2959
01:03
I never heard another scientist tell that kind of story
20
63672
3032
01:06
until last year.
21
66728
1366
01:08
A scientist in Guam wrote,
22
68623
2005
01:10
"I cried right into my mask,"
23
70652
1547
01:12
seeing the damage on the reefs.
24
72223
2210
01:15
Then a scientist in Australia wrote,
25
75469
1941
01:17
"I showed my students the results of our coral surveys,
26
77434
2997
01:20
and we wept."
27
80455
1352
01:22
Crying about corals is having a moment, guys.
28
82716
2648
01:25
(Laughter)
29
85388
1134
01:26
And that's because reefs in the Pacific
30
86546
1944
01:28
are losing corals faster than we've ever seen before.
31
88514
2834
01:31
Because of climate change,
32
91689
1272
01:32
the water is so hot for so long in the summers,
33
92985
2809
01:35
that these animals can't function normally.
34
95818
2175
01:38
They're spitting out the colored algae that lives in their skin,
35
98494
3028
01:41
and the clear bleached tissue that's left usually starves to death
36
101546
5065
01:46
and then rots away.
37
106635
1254
01:48
Then the skeletons are overgrown by algae.
38
108944
2363
01:51
This is happening over an unbelievable scale.
39
111781
2323
01:54
The Northern Great Barrier Reef lost two-thirds of its corals last year
40
114128
4136
01:58
over a distance of hundreds of miles,
41
118288
2555
02:00
then bleached again this year,
42
120867
1802
02:02
and the bleaching stretched further south.
43
122693
2118
02:05
Reefs in the Pacific are in a nosedive right now,
44
125824
2314
02:08
and no one knows how bad it's going to get,
45
128162
2539
02:10
except ...
46
130725
1369
02:12
over in the Caribbean where I work,
47
132118
1939
02:14
we've already been through the nosedive.
48
134081
2078
02:16
Reefs there have suffered through centuries of intense human abuse.
49
136519
3944
02:20
We kind of already know how the story goes.
50
140764
2183
02:23
And we might be able to help predict what happens next.
51
143283
3826
02:27
Let's consult a graph.
52
147774
1575
02:32
Since the invention of scuba,
53
152442
1381
02:33
scientists have measured the amount of coral on the seafloor,
54
153847
2981
02:36
and how it's changed through time.
55
156852
1666
02:39
And after centuries of ratcheting human pressure,
56
159216
2461
02:41
Caribbean reefs met one of three fates.
57
161701
2601
02:44
Some reefs lost their corals very quickly.
58
164774
2246
02:49
Some reefs lost their corals more slowly,
59
169065
3444
02:52
but kind of ended up in the same place.
60
172533
2993
02:55
OK, so far this is not going very well.
61
175550
1937
02:58
But some reefs in the Caribbean --
62
178064
2263
03:00
the ones best protected
63
180351
1893
03:02
and the ones a little further from humans --
64
182268
2714
03:05
they managed to hold onto their corals.
65
185006
3541
03:09
Give us a challenge.
66
189227
1483
03:11
And, we almost never saw a reef hit zero.
67
191909
2656
03:16
The second time I cried underwater
68
196110
2486
03:18
was on the north shore of Curaçao, 2011.
69
198620
3410
03:22
It was the calmest day of the year,
70
202054
1684
03:23
but it's always pretty sketchy diving there.
71
203762
2369
03:26
My boyfriend and I swam against the waves.
72
206155
2096
03:28
I watched my compass so we could find our way back out,
73
208275
2674
03:30
and he watched for sharks,
74
210973
1630
03:32
and after 20 minutes of swimming that felt like an hour,
75
212627
2856
03:35
we finally dropped down to the reef,
76
215507
1716
03:37
and I was so shocked,
77
217247
1559
03:38
and I was so happy
78
218830
1646
03:40
that my eyes filled with tears.
79
220500
1995
03:43
There were corals 1,000 years old lined up one after another.
80
223219
4925
03:48
They had survived the entire history of European colonialism in the Caribbean,
81
228996
4686
03:53
and for centuries before that.
82
233706
2135
03:57
I never knew what a coral could do when it was given a chance to thrive.
83
237465
4158
04:02
The truth is that even as we lose so many corals,
84
242660
3383
04:06
even as we go through this massive coral die-off,
85
246067
3056
04:09
some reefs will survive.
86
249147
1851
04:11
Some will be ragged on the edge,
87
251732
1654
04:13
some will be beautiful.
88
253410
1889
04:15
And by protecting shorelines and giving us food to eat
89
255911
2691
04:18
and supporting tourism,
90
258626
1749
04:20
they will still be worth billions and billions of dollars a year.
91
260399
3122
04:24
The best time to protect a reef was 50 years ago,
92
264043
2591
04:26
but the second-best time is right now.
93
266658
2918
04:31
Even as we go through bleaching events,
94
271115
1951
04:33
more frequent and in more places,
95
273090
2543
04:35
some corals will be able to recover.
96
275657
2275
04:38
We had a bleaching event in 2010 in the Caribbean
97
278792
2852
04:41
that took off big patches of skin on boulder corals like these.
98
281668
3585
04:46
This coral lost half of its skin.
99
286172
2613
04:48
But if you look at the side of this coral a few years later,
100
288809
4227
04:53
this coral is actually healthy again.
101
293060
2348
04:55
It's doing what a healthy coral does.
102
295432
2297
04:57
It's making copies of its polyps,
103
297753
2098
04:59
it's fighting back the algae
104
299875
1455
05:01
and it's reclaiming its territory.
105
301354
1772
05:04
If a few polyps survive,
106
304195
1165
05:05
a coral can regrow;
107
305384
1173
05:06
it just needs time and protection and a reasonable temperature.
108
306581
4105
05:11
Some corals can regrow in 10 years --
109
311188
1809
05:13
others take a lot longer.
110
313021
1723
05:14
But the more stresses we take off them locally --
111
314768
2651
05:17
things like overfishing, sewage pollution, fertilizer pollution,
112
317443
3994
05:21
dredging, coastal construction --
113
321461
2445
05:23
the better they can hang on as we stabilize the climate,
114
323930
2870
05:26
and the faster they can regrow.
115
326824
1810
05:29
And as we go through the long, tough and necessary process
116
329766
3738
05:33
of stabilizing the climate of planet Earth,
117
333528
2605
05:36
some new corals will still be born.
118
336157
2430
05:39
This is what I study in my research.
119
339143
1907
05:41
We try to understand how corals make babies,
120
341498
2547
05:44
and how those babies find their way to the reef,
121
344069
2674
05:46
and we invent new methods to help them survive
122
346767
2302
05:49
those early, fragile life stages.
123
349093
1933
05:51
One of my favorite coral babies of all time
124
351904
3001
05:54
showed up right after Hurricane Omar.
125
354929
2010
05:56
It's the same species I was studying before the storm,
126
356963
2691
05:59
but you almost never see babies of this species --
127
359678
2432
06:02
it's really rare.
128
362134
1215
06:03
This is actually an endangered species.
129
363373
2314
06:06
In this photo, this little baby coral, this little circle of polyps,
130
366219
3496
06:09
is a few years old.
131
369739
1424
06:11
Like its cousins that bleach,
132
371616
1469
06:13
it's fighting back the algae.
133
373109
1836
06:14
And like its cousins on the north shore,
134
374969
1925
06:16
it's aiming to live for 1,000 years.
135
376918
3041
06:21
What's happening in the world and in the ocean
136
381018
2850
06:23
has changed our time horizon.
137
383892
1798
06:26
We can be incredibly pessimistic on the short term,
138
386457
3039
06:29
and mourn what we lost
139
389520
1315
06:30
and what we really took for granted.
140
390859
2665
06:34
But we can still be optimistic on the long term,
141
394028
2750
06:36
and we can still be ambitious about what we fight for
142
396802
2478
06:39
and what we expect from our governments,
143
399304
3098
06:42
from our planet.
144
402426
1291
06:44
Corals have been living on planet Earth for hundreds of millions of years.
145
404364
3730
06:48
They survived the extinction of the dinosaurs.
146
408118
2193
06:50
They're badasses.
147
410335
1265
06:52
(Laughter)
148
412189
1477
06:53
An individual coral can go through tremendous trauma and fully recover
149
413690
4539
06:58
if it's given a chance and it's given protection.
150
418253
2786
07:02
Corals have always been playing the long game,
151
422042
2829
07:05
and now so are we.
152
425539
1422
07:07
Thanks very much.
153
427612
1153
07:08
(Applause)
154
428789
2848
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7