00:00You are in a park, you enjoy a normal day when suddenly,
00:04the clouds and clouds appear on you.
00:07But it doesn't take a few minutes or a few hours,
00:09it continues for weeks, and all around you is slowly deprived of light.
00:14It's exactly what happens at the bottom of the ocean,
00:17and scientists have given it a name.
00:19They call it the waves sombre marine.
00:21You may have heard of the waves of marine heat.
00:24It's when the ocean becomes much too hot,
00:26and the rest is during weeks or months.
00:28It's because the ocean acts like a giant sponge for the planet.
00:33When the atmosphere pierce the heat of the sun, the ocean absorb it.
00:37Sometimes, the currents of heat rest at the same place,
00:40like the cold water which bubbles in a dark water,
00:43cuisant lentement everything that is located.
00:46The heat decimes what can't move,
00:48like the birds or the birds,
00:50while the fish are frozen to the sea,
00:53or suffer from the oxygen oxygen.
00:55And as the plants and the reefs are the base of the alimentary chain,
00:59the effects of all the ecosystem oceanic.
01:02The waves of marine heat are a huge problem.
01:05However, the waves sombre are almost as serious,
01:08but in a completely different way.
01:11A vague sombre marine,
01:12it's obviously not a question of heat.
01:14It's the light that suddenly disappears,
01:16there where it should exist.
01:18If we imagine the ocean as an immense atmosphere in the sea,
01:21where the light of the sun enters normally by the windows,
01:24and clear each stage,
01:25the waves sombre,
01:26it would be like if someone would fill this atmosphere
01:28with a heavy fumet.
01:29It happens when the water is heavy,
01:32and turbid and turbid and turbid and turbid.
01:35The water itself becomes a brouillard
01:37which devore the lumière.
01:39In general, the sand,
01:40the sand,
01:40the algae and all sorts of organic debris
01:42microscopically
01:43are brassed and put in suspension in the water,
01:46dispersant and absorbant the light of the sun
01:48before they reach the sun marin.
01:50When it becomes enough heavy,
01:52the sun marin plonges in the obscurity.
01:54All the light that depends on the sun
01:56to be nourished there in the bottom
01:57is then affamée.
01:59And the most strange,
02:00it's that we don't talk about the abyss,
02:01at kilometers deep deep,
02:03where the light doesn't come out of any way.
02:06All this happens close to the coast,
02:08in the deep zones where the marine plants
02:11need the sun to survive.
02:13What makes the waves so vicious
02:14is that they are very easy to rater.
02:17From the surface,
02:19everything can seem normal,
02:20even for satellites.
02:22We can be stationed at a boat
02:23just on the top of a sombre
02:25without nothing to notice anormal.
02:27That's why this phenomenon
02:28is long passed in aperçu
02:29and has been studied seriously
02:31that recently.
02:32For identifying
02:33what was the light of the ocean
02:35at the bottom of the ocean,
02:36scientists have begun
02:37to recouper the data
02:38like detectives.
02:40They have to find out
02:41in the archives
02:41and build a sort of machine
02:43to remodel the time
02:44with ancient data.
02:45They have gathered
02:4616 years of continuous measures
02:47of light
02:48taken directly to the center of Santa Barbara.
02:52Then,
02:52they have found it
02:53with more than 20 years
02:54of light bulbs
02:55from the coast of New Zealand.
02:58In general,
02:59they have made the images
03:00of the ocean
03:01on the last two decades
03:02to see what they had been missing.
03:05In combination
03:06all these data,
03:07the researchers
03:07discovered a precise event
03:08in New Zealand
03:09where the marine plant
03:10has not received
03:11almost no use of light
03:12for 64 days.
03:15Imagine
03:16that the sun
03:16will be found
03:17on the 1st of November
03:18and it will not be released
03:19until the day of the year.
03:20If it happened on the Earth,
03:22it would be a catastrophe
03:23for all
03:23who needs light
03:24to push.
03:26Think about
03:27your interior plant.
03:28If you put a
03:29in the garden
03:29in a place
03:30for a week,
03:31it would probably be
03:32a triste mine,
03:33but it would be
03:34that if you left it
03:36there for two months,
03:37it would be
03:38and would be
03:38slowly
03:39at the end.
03:39At the end,
03:41at the end,
03:41if a forest
03:42lost the sun
03:42for 64 days,
03:44the forest
03:45would be
03:45and other animals
03:47would have no food
03:48and the entire
03:50food chain
03:50would vacill
03:52It's the same
03:52biological principle
03:53for the world
03:54of Sumara,
03:55because he also needs
03:56the sun.
03:57In the bottom,
03:58at the place
03:58of the plants
03:58and of the herbs,
03:59there are huge forests
04:00of kelp
04:01and the plants
04:01of marine plants.
04:03These are the
04:03stations service
04:04to oxygen
04:04of the sea.
04:05They capture
04:06the sun's light
04:07and turn it into
04:08carbon for all
04:09the ecosystem.
04:10When a long
04:11wave somber
04:11hits,
04:12they burn their
04:13batteries
04:13until nothing
04:14to rip.
04:15The same sort
04:16touches the kelp.
04:17They start to
04:18deteriorate.
04:19The fish who
04:20are nourishing
04:20are famous
04:21and suddenly,
04:22a marine land
04:23full of life
04:24has become a
04:25ghost.
04:26The marine plants
04:27can also touch
04:31those who are
04:31high in the
04:32water.
04:32The marine plants
04:33are often
04:34chastent
04:35but in reality,
04:36they depend
04:37a lot
04:37of the sun's light.
04:39Many
04:39and big fish
04:40comptent
04:41on the light
04:41and the contrast
04:42for chasing.
04:43They are made
04:44to see
04:44some sombres
04:49of the sea.
05:01They are
05:01as
05:01as
05:02as
05:02as
05:02as
05:03as
05:04as
05:04as
05:04as
05:05as
05:05GR comin.
05:06Theyle
05:15one
05:17will
05:35up to the quai. The fishing villages depend on a marine life,
05:38with a previsible behavior. If the fish can no longer nourish, they go.
05:43The boats come empty, and the boats rentraqués are light.
05:47The boats savent to read a météo radar to avoid a storm,
05:50but there is no prevision for an ocean that lacks light.
05:54It also creates a cast-tet for professionals who work under the surface.
05:58The sound helps, but the researchers and research teams always use their eyes.
06:02A vague sombre modifie la façon dont la lumière se propage dans l'eau,
06:06transformant un site de travail familier en un brouillard opaque.
06:10La navigation devient une devinette. Les relevés échouent.
06:14C'est un nouveau facteur de stress, que les experts n'anticipent jamais
06:17parce que, jusqu'à récemment, ils n'étaient même pas reconnus.
06:21On a parlé de comment les vagues sombres se produisent, mais qu'est-ce qui les déclenche ?
06:26Eh bien, la plupart du temps, c'est quelque chose de violent et chaotique en surface.
06:29Des événements comme les grosses tempêtes, les inondations,
06:33des rivières débordant de ruissellement.
06:35Quand d'énormes tempêtes frappent les terres, elles arrachent le sol,
06:38la boue et la matière organique du paysage et les déversent directement dans l'océan.
06:43Tout ce matériau se répand en d'immenses panaches sous-marins
06:46qui peuvent transformer une eau côtière limpide en chocolat au lait,
06:49quasiment du jour au lendemain.
06:52Les scientifiques repèrent facilement les panaches de sédiments en surface,
06:55mais ils ne peuvent pas toujours dire à quel point il fait sombre tout en bas, sur le fond marin.
06:59Les côtes s'assombrissent à mesure que les nuages de sédiments s'étendent.
07:03Le soleil peut briller au-dessus, mais l'eau est tellement chargée de particules qu'aucune lumière ne passe.
07:08Les courants côtiers piègent souvent cette eau trouble sur place.
07:12Alors l'obscurité persiste bien après la fin de la pluie.
07:15C'est pourquoi les vagues sombres apparaissent souvent après des épisodes météo extrêmes.
07:19Ça crée un décalage trompeur.
07:21La tempête passe et on suppose que la récupération a commencé.
07:25Mais sous l'eau, la colonne d'eau est encore chargée de débris qui bloquent la lumière.
07:30Ce qui ressemble à un retour à la normale en surface,
07:33c'est en réalité des semaines d'obscurité prolongée en dessous.
07:36Et à mesure que les tempêtes s'intensifient,
07:38on voit de plus en plus de ces situations de vagues sombres apparaître.
07:41L'océan subit de plein fouet des épisodes intenses de boue et de panache organique qui provoquent tout ça.
07:47Les fortes pluies entraînent davantage d'inondations et de glissements de terrain,
07:51transformant les rivières en tapis roulants qui déversent des tonnes de terre et de débris dans la mer.
07:56Même après le passage de la tempête,
07:58les vagues et les courants peuvent maintenir ce mélange trouble en suspension,
08:01gardant l'eau opaque à un bon moment, comme une boule à neige qu'on vient de secouer.
08:06Alors, quelle est la suite ?
08:08Les scientifiques prennent enfin les vagues sombres marines au sérieux,
08:11au lieu de les balayer comme un obscur mythe océanique.
08:14Maintenant qu'on a un nom pour ces épisodes d'extinction de lumière et un moyen de les suivre,
08:18la prochaine étape est simple !
08:20Il faut installer plus de capteurs de lumière aux endroits stratégiques.
08:23Il faut aussi comprendre le lien entre les vagues sombres, les tempêtes, le ruissellement et les proliférations d'algues.
08:30Enfin, il faut identifier le moment précis où les écosystèmes ne peuvent plus se rétablir.
08:35En gros, on est en train de créer un bulletin météo de la lumière sous-marine,
08:39parce qu'il s'avère que l'océan n'a pas seulement des tempêtes et des vagues de chaleur.
08:43Parfois, il a aussi sa propre forme d'éclipse.
08:45Sous-titrage Société Radio-Canada
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