0:00:01 > 0:00:04Our planet is the greatest living puzzle in the universe.
0:00:06 > 0:00:09A collection of worlds within worlds.
0:00:09 > 0:00:13Each one a self-contained ecosystem bursting with life.
0:00:17 > 0:00:19But how do they work?
0:00:20 > 0:00:23The intricate web of relationships
0:00:23 > 0:00:27and the influence of natural forces
0:00:27 > 0:00:32makes each microworld complex and unique.
0:00:32 > 0:00:37So to discover their secrets, we need to explore them one by one.
0:00:39 > 0:00:42Untangle their interlocking pieces
0:00:42 > 0:00:47and ultimately reveal the vital piece,
0:00:47 > 0:00:48the key to life itself,
0:00:48 > 0:00:53hidden deep within each of nature's microworlds.
0:01:03 > 0:01:08Our most northern microworld sits well within the Arctic Circle.
0:01:10 > 0:01:13The Arctic, at the top of our planet,
0:01:13 > 0:01:16is covered in a permanent cap of ice.
0:01:21 > 0:01:25This close to the North Pole, the sea is nearly always frozen.
0:01:28 > 0:01:32Temperatures can be well below minus 50.
0:01:38 > 0:01:42In winter, the sun does not rise for three and a half months,
0:01:42 > 0:01:45staying just below the horizon
0:01:45 > 0:01:49and casting everything in an eerie blue half-light.
0:01:52 > 0:01:55Even when the sun does appear above the horizon,
0:01:55 > 0:01:57for much of the year, the rays are too weak
0:01:57 > 0:02:01to be any use for primary production.
0:02:05 > 0:02:10But there is one area of the Arctic Circle that's different -
0:02:10 > 0:02:15our microworld of the extreme north,
0:02:15 > 0:02:17Svalbard.
0:02:21 > 0:02:22It looks barren,
0:02:22 > 0:02:27but in Svalbard there are more polar bears than humans.
0:02:27 > 0:02:30It is home to the most northerly population
0:02:30 > 0:02:33of large herbivores in the world,
0:02:33 > 0:02:38and for its latitude, it's unusually rich in life.
0:02:38 > 0:02:43So what makes Svalbard so different to the rest of the Arctic?
0:02:47 > 0:02:51To understand this, we need to look at what makes this microworld tick.
0:02:51 > 0:02:54Unravel the working parts that make this place so special,
0:02:54 > 0:02:58both the animals and the environment.
0:03:00 > 0:03:04And to do that means understanding how the animals that live here
0:03:04 > 0:03:06manage through the seasons.
0:03:08 > 0:03:12When looking at the animals in this microworld,
0:03:12 > 0:03:16the best place to start is at the very top.
0:03:21 > 0:03:24How can a place seemingly locked in ice
0:03:24 > 0:03:29support so many of the world's largest land predator,
0:03:29 > 0:03:31the polar bear?
0:03:35 > 0:03:38The bears hunt out on the thick sea ice.
0:03:43 > 0:03:46But if the weather gets too bad to hunt,
0:03:46 > 0:03:49which it can here for weeks, the bears have the ability
0:03:49 > 0:03:53to curl up and slip into a sort of mini-hibernation and ride it out
0:03:53 > 0:03:57without doing too much damage to their energy reserves.
0:04:00 > 0:04:03This trick can be the difference between life and death.
0:04:10 > 0:04:14And the reason they patrol the sea ice is the type of food they eat.
0:04:17 > 0:04:20Their favourite food is the ringed seal.
0:04:24 > 0:04:28The ringed seal can live out on the ice all year round,
0:04:28 > 0:04:32using their claws to keep holes open in the ice,
0:04:32 > 0:04:37so that if danger appears they have an escape hatch.
0:04:51 > 0:04:54To be able to survive in this freezing water,
0:04:54 > 0:04:58the seals put on a thick layer of warm, fatty blubber.
0:05:05 > 0:05:10And this energy-rich blubber is what the bears are after.
0:05:14 > 0:05:17But their problem is getting their paws on it.
0:05:27 > 0:05:30The seals give birth to their pups out on the freezing ice.
0:05:34 > 0:05:36A risky business with bears about.
0:05:44 > 0:05:47Bears use their nose to find food.
0:05:47 > 0:05:50They can pick up the scent of a seal buried under a metre of snow
0:05:50 > 0:05:54from nearly a kilometre away.
0:05:55 > 0:06:00They are the apex predators, the kings of our microworld.
0:06:03 > 0:06:09Weighing up to 1,000 kilos, they can run at up to 60 kilometres an hour.
0:06:29 > 0:06:31The bears might be king out here
0:06:31 > 0:06:34but only 2% of bear hunts are successful.
0:06:34 > 0:06:37But with a food source this rich,
0:06:37 > 0:06:40a 2% success rate is just enough to survive.
0:06:44 > 0:06:48With an estimated population of 6 million ringed seals,
0:06:48 > 0:06:52predation is just nature's way of keeping the system in balance.
0:06:57 > 0:07:00Predators keep prey populations fit and healthy
0:07:00 > 0:07:05and to live here, you really do need to be fit and healthy.
0:07:09 > 0:07:11The bears walk such a thin line
0:07:11 > 0:07:15that they only eat the blubbery, energy-rich parts of the seal.
0:07:17 > 0:07:21Not wasting time on the other parts of the seal that don't give them
0:07:21 > 0:07:26the maximum return for their effort, before moving on to find more.
0:07:28 > 0:07:30And this means there are plenty of leftovers.
0:07:34 > 0:07:38Arctic foxes have learnt that following polar bears pays off.
0:07:38 > 0:07:42The foxes clean up the meat that the bears don't bother with.
0:07:46 > 0:07:48It seems counter-intuitive
0:07:48 > 0:07:53but if you're an arctic fox, out here the best place to be
0:07:53 > 0:07:57is right behind one of the world's most dangerous predators.
0:08:00 > 0:08:04Without the bears and their picky habits,
0:08:04 > 0:08:06the foxes would struggle to survive.
0:08:13 > 0:08:16The bears have shown us how they do it at the top,
0:08:16 > 0:08:20but what about the bottom of the food chain?
0:08:20 > 0:08:22Where are the primary producers?
0:08:25 > 0:08:27To find them, we have to follow
0:08:27 > 0:08:30another of Svalbard's tough winter residents.
0:08:30 > 0:08:32Reindeer.
0:08:35 > 0:08:38Our microworld has the most northerly population
0:08:38 > 0:08:40of large herbivores in the world
0:08:40 > 0:08:45and they're literally scraping to get by.
0:08:45 > 0:08:48These reindeer have evolved into a subspecies.
0:08:50 > 0:08:53Unlike their mainland cousins, they are able to digest
0:08:53 > 0:08:56enough of the tough vegetation they find here in winter to survive.
0:09:00 > 0:09:03They also have shorter legs, longer fur,
0:09:03 > 0:09:07and most importantly, the ability to put on thick fat reserves.
0:09:11 > 0:09:14These adaptations are great for the cold
0:09:14 > 0:09:16but mean they are not good runners,
0:09:16 > 0:09:20which sounds disastrous with polar bears about,
0:09:20 > 0:09:25but actually, the bears very rarely hunt them.
0:09:31 > 0:09:35There is vegetation here underneath the ice
0:09:35 > 0:09:37but it's hard to get to
0:09:37 > 0:09:40and conditions here are too harsh for most plants.
0:09:43 > 0:09:46For the reindeer of Svalbard,
0:09:46 > 0:09:51starvation is the main cause of death.
0:09:51 > 0:09:54To survive here, the reindeer, just like the ringed seals,
0:09:54 > 0:09:57have to depend on their fat reserves.
0:10:02 > 0:10:06But you can't build up fat reserves with such little food,
0:10:06 > 0:10:09so there must be times of plenty.
0:10:11 > 0:10:13And that is one of the things that makes Svalbard
0:10:13 > 0:10:17so different to other Arctic locations.
0:10:23 > 0:10:25Because, for just eight weeks of the year,
0:10:25 > 0:10:29something truly fabulous happens in Svalbard.
0:10:29 > 0:10:31Summer.
0:10:34 > 0:10:37Spring and autumn do happen,
0:10:37 > 0:10:43but the sun stays so low in the sky, its rays only skim the surface
0:10:43 > 0:10:49and lack the intensity needed to be of any use to the primary producers.
0:10:49 > 0:10:54But as summer gets closer, the sun rises higher in the sky,
0:10:54 > 0:10:59the temperature increases and the sea ice starts to melt.
0:11:04 > 0:11:06It's the signal for millions of sea birds
0:11:06 > 0:11:10to fly in from the south to breed.
0:11:13 > 0:11:17The short summer means that by the time they have arrived,
0:11:17 > 0:11:20found a mate and hatched their eggs, there will only be three weeks left
0:11:20 > 0:11:24to rear their young before they have to head south again
0:11:24 > 0:11:26before winter once more closes in.
0:11:28 > 0:11:32So how do they manage this so quickly?
0:11:34 > 0:11:39Well, the answer is that summer here has 24 hours of sunlight a day,
0:11:39 > 0:11:42and they use every minute of it.
0:11:49 > 0:11:51Both the males and the females
0:11:51 > 0:11:55bring food back to their growing chick almost constantly.
0:11:55 > 0:11:59The threat of the returning ice is an ever-present deadline.
0:12:01 > 0:12:04They have become absolute specialists
0:12:04 > 0:12:07in collecting as much food as possible, as quickly as possible.
0:12:10 > 0:12:12These guillemots can dive to 130 metres
0:12:12 > 0:12:16and hold their breath for up to three minutes in the search of food.
0:12:18 > 0:12:21But why, if there is such a tight time limit,
0:12:21 > 0:12:24do they come to Svalbard in the first place?
0:12:31 > 0:12:34The first things to react to the winter's weakening grip
0:12:34 > 0:12:38are tiny organisms called phytoplankton.
0:12:40 > 0:12:42They combine the sun's light
0:12:42 > 0:12:45and carbon dioxide found in the sea water
0:12:45 > 0:12:47to photosynthesize like plants
0:12:47 > 0:12:51and they start doing this even under the ice,
0:12:51 > 0:12:54forming a greeny-brown crust.
0:13:00 > 0:13:04And as more sea ice melts and the sun gets higher in the sky,
0:13:04 > 0:13:08the phytoplankton blooms on a monumental scale.
0:13:11 > 0:13:16These are the marine equivalent of grass and are the primary producers.
0:13:18 > 0:13:23And these feed the next link on the food chain,
0:13:23 > 0:13:24millions of crustaceans,
0:13:24 > 0:13:27which move around grazing like tiny underwater cows.
0:13:29 > 0:13:32They feed the fish, which feed the birds and the seals
0:13:32 > 0:13:35and so on right up to the top,
0:13:35 > 0:13:37the polar bear.
0:13:40 > 0:13:44The melting ice is good news for most,
0:13:44 > 0:13:47but not for the bears.
0:13:50 > 0:13:55This is the start of the bears' lean times.
0:13:58 > 0:14:02Now it is their turn to rely on their fat reserves to survive.
0:14:05 > 0:14:10Their Latin name means "sea bear", but without the sea ice to hunt on,
0:14:10 > 0:14:14the advantage has turned to the seals fishing out in the open sea.
0:14:25 > 0:14:29But all this disappearing snow and melting ice has a positive impact
0:14:29 > 0:14:34on almost everything else within our microworld.
0:14:44 > 0:14:47As the ground thaws, plants burst into life,
0:14:47 > 0:14:52joining in the sprint to cram a full life cycle
0:14:52 > 0:14:55into this tiny window of opportunity.
0:15:00 > 0:15:05The most prolific meadows are found below the sea bird colonies,
0:15:05 > 0:15:08fed by the tonnes of natural fertiliser
0:15:08 > 0:15:11in the form of bird droppings.
0:15:11 > 0:15:13So even Svalbard's flowering plants
0:15:13 > 0:15:17are directly benefiting from the rich seas surrounding this island.
0:15:22 > 0:15:24As do the reindeer, that come to these meadows
0:15:24 > 0:15:29to feed on the new energy-rich growth fed by the bird colonies.
0:15:32 > 0:15:35The reindeer are in the same race as is all life here,
0:15:35 > 0:15:38to make the absolute most of summer.
0:15:38 > 0:15:41This is their only chance to build the fat reserves
0:15:41 > 0:15:45they will depend upon to see them through another winter.
0:15:45 > 0:15:47Nothing distracts them.
0:15:52 > 0:15:56Although feeding so close to the bird colonies has its dangers.
0:15:56 > 0:15:59Arctic skuas, ground nesting birds,
0:15:59 > 0:16:03don't take kindly to big clumsy reindeer near their eggs.
0:16:03 > 0:16:06Their sharp beaks can cause real damage.
0:16:06 > 0:16:10The problem is the reindeer are not really built to run.
0:16:10 > 0:16:13They are so specialised to cold weather
0:16:13 > 0:16:18that even the shortest run leaves them hot and bothered.
0:16:20 > 0:16:26The areas around the bird colonies are also a focus for the foxes
0:16:26 > 0:16:29which are also snatching this once a year chance
0:16:29 > 0:16:31to raise a family.
0:16:36 > 0:16:40And with eight hungry mouths to feed, it's a relentless job.
0:16:50 > 0:16:52But winter will come around so fast,
0:16:52 > 0:16:55that even with both the male and female working flat out,
0:16:55 > 0:17:01it's likely only two cubs will survive to become adults.
0:17:03 > 0:17:05Although there might be a lot of food
0:17:05 > 0:17:07in our arctic microworld right now,
0:17:07 > 0:17:11it's apparent that in this boom and bust ecosystem
0:17:11 > 0:17:13these animals are not rolling in the good times,
0:17:13 > 0:17:17they are gambling on the short summer to provide.
0:17:20 > 0:17:24So how do the animals here cope with pressure like this?
0:17:26 > 0:17:29Well, they are forced to take risks,
0:17:29 > 0:17:31and as the days once more get shorter,
0:17:31 > 0:17:35the hungry bears start to take some big risks.
0:17:37 > 0:17:41Without the ice, they have no way of getting to the seals.
0:17:46 > 0:17:50It is hard to imagine a polar bear meeting its match on land,
0:17:50 > 0:17:53but at times, desperation drives the bears
0:17:53 > 0:17:56to take on some unusual opponents.
0:18:02 > 0:18:08Walruses can be three times as heavy as an adult polar bear.
0:18:08 > 0:18:11Their tusks can weigh up to 10 lbs and measure a metre long
0:18:11 > 0:18:15and with one and a half tonnes of mammal behind them,
0:18:15 > 0:18:17they also make formidable weapons.
0:18:23 > 0:18:28Apex predators, like the polar bears need to be on top form to hunt.
0:18:28 > 0:18:31They need to use their energy wisely,
0:18:31 > 0:18:35balancing the risk they take against the reward they stand to gain
0:18:35 > 0:18:38from a successful hunt.
0:18:39 > 0:18:42The polar bear might be king of our microworld
0:18:42 > 0:18:46but even he lives his life on the edge at times.
0:18:47 > 0:18:51And on this occasion, the gamble has not paid off.
0:18:54 > 0:18:58All the animals have to balance the potential benefit
0:18:58 > 0:19:00against the possible loss.
0:19:00 > 0:19:06In general, the rewards outweigh the risk,
0:19:06 > 0:19:10but there's a fine line that separates success from failure.
0:19:14 > 0:19:16And if you've only got three weeks to rear your young,
0:19:16 > 0:19:21winter coming a week early would spell disaster.
0:19:21 > 0:19:25So the birds here are balancing right on the edge.
0:19:27 > 0:19:31So why do they take the risk?
0:19:31 > 0:19:34Well, its because Svalbard is unique
0:19:34 > 0:19:39and for this short period, there's a lot of food guaranteed.
0:19:41 > 0:19:43But they have to get out of here
0:19:43 > 0:19:46before the ice returns in a matter of days.
0:19:48 > 0:19:52And this means pushing your child off a 300-metre cliff
0:19:52 > 0:19:54before it can fly.
0:20:01 > 0:20:05The adults follow them calling all the way.
0:20:09 > 0:20:11But it's a long way down
0:20:11 > 0:20:15when they've never tried their wings before.
0:20:25 > 0:20:29Getting to the water is only the first challenge.
0:20:32 > 0:20:36With winter now approaching fast, they've got to leave.
0:20:37 > 0:20:42The trouble is that where they want to go to is 1200 miles away
0:20:42 > 0:20:48and the only way to get there is to swim.
0:20:48 > 0:20:51Some don't even make it as far as the sea.
0:20:51 > 0:20:55Soft bodies and feathers mean they can literally bounce
0:20:55 > 0:20:58without sustaining serious injury.
0:20:58 > 0:21:02But they do have to finish the last bit on foot.
0:21:04 > 0:21:07And some land a long way from the sea.
0:21:12 > 0:21:17And in a microworld on a deadline, not everyone can win when gambling.
0:21:23 > 0:21:25When life is so finely tuned,
0:21:25 > 0:21:28one creature's loss is another's gain.
0:21:33 > 0:21:34For this family of foxes,
0:21:34 > 0:21:37this final feast could be the difference
0:21:37 > 0:21:39between surviving this year's winter and not.
0:21:42 > 0:21:44Even with eight hungry mouths to feed,
0:21:44 > 0:21:48the foxes can't eat all the birds they collect so they store them.
0:21:52 > 0:21:55These larders full of food
0:21:55 > 0:21:58help the foxes hedge their bets against the winter
0:21:58 > 0:22:00when there's nothing else to eat.
0:22:05 > 0:22:09With such long, light days, you can get a lot done.
0:22:11 > 0:22:12So is this length of day
0:22:12 > 0:22:17the key to a high level of productivity in our microworld?
0:22:17 > 0:22:20Sunlight after all is the origin of all energy on Earth,
0:22:20 > 0:22:24converted into food by those that can photosynthesise,
0:22:24 > 0:22:28like those phytoplankton off Svalbard's coast.
0:22:37 > 0:22:41All the other areas this far North have the same amount of sunlight,
0:22:41 > 0:22:45but only the waters around Svalbard can claim to be responsible
0:22:45 > 0:22:49for 50% of the Arctic's entire primary production.
0:22:52 > 0:22:56So what is going on here that makes this place so special?
0:23:00 > 0:23:04We need to know what phytoplankton gets in Svalbard
0:23:04 > 0:23:06that it doesn't get anywhere else.
0:23:11 > 0:23:15Besides sunlight, the phytoplankton also needs
0:23:15 > 0:23:19other substances like nitrates and phosphates to flourish,
0:23:19 > 0:23:22and these are hard to find at the sea's surface.
0:23:25 > 0:23:29This is because they generally sink to the bottom and stay there.
0:23:32 > 0:23:34So how do the primary producers get at it
0:23:34 > 0:23:37if it's all trapped at the bottom of the sea?
0:23:42 > 0:23:45Incredibly, the answer to this crucial question
0:23:45 > 0:23:49comes from the Caribbean
0:23:49 > 0:23:54and it holds the secret to what makes Svalbard so different.
0:24:04 > 0:24:07A major force in the Atlantic is the Gulf Stream,
0:24:07 > 0:24:12a flow of warm water that moves from the south of Florida,
0:24:12 > 0:24:15north up the coast of America, crosses the ocean
0:24:15 > 0:24:19and helps to keep the UK and northern Europe warm and wet.
0:24:21 > 0:24:24Its most northerly arm reaches Svalbard,
0:24:24 > 0:24:28warming the waters in our microworld by only a few degrees
0:24:28 > 0:24:30but enough to help melt the ice.
0:24:34 > 0:24:37This warm current collides with cold water flowing from the Arctic
0:24:37 > 0:24:41and together, like a spoon in a giant bowl of soup,
0:24:41 > 0:24:45they stir up the bottom causing the nitrates and phosphates
0:24:45 > 0:24:48to come to the surface.
0:24:58 > 0:25:01And it's this rich upwelling that really kicks off
0:25:01 > 0:25:04Svalbard's phytoplankton bloom.
0:25:14 > 0:25:16The meeting of these two currents
0:25:16 > 0:25:21holds the key to the unique success of this chilly microworld.
0:25:23 > 0:25:29The phytoplankton couldn't bloom at all without the sun
0:25:29 > 0:25:32and this far north, the sun couldn't reach into waters
0:25:32 > 0:25:37without the Gulf Stream melting the ice.
0:25:37 > 0:25:40And there wouldn't be enough fuel to feed it all
0:25:40 > 0:25:43without the collision and mixing of the currents.
0:25:48 > 0:25:51And without this incredible level of primary production
0:25:51 > 0:25:54at the bottom of the food chain, none of the animals
0:25:54 > 0:25:57would be able to take the gamble of living here at all.
0:26:00 > 0:26:01And so productive is this microworld
0:26:01 > 0:26:05that it supports the largest land predator on Earth.
0:26:08 > 0:26:12The bears gamble so heavily on this environment
0:26:12 > 0:26:16that they've become too specialised to live anywhere else.
0:26:16 > 0:26:21They rely on the food web below them and the frozen sea to get at it.
0:26:26 > 0:26:31But the bears don't just get by here in Svalbard, they thrive,
0:26:31 > 0:26:35and that's because the females can build up enough of a fat reserve
0:26:35 > 0:26:38to be able to live under the snow for six months of the year,
0:26:38 > 0:26:41eating nothing at all,
0:26:41 > 0:26:45and the reason they do this becomes obvious in spring.
0:26:47 > 0:26:49As if not eating for half the year wasn't enough,
0:26:49 > 0:26:54she has also been using her own body to feed her two new cubs as well.
0:26:57 > 0:27:00Now they are ready to face the new challenges
0:27:00 > 0:27:03that lie in our boom and bust microworld.
0:27:05 > 0:27:08Luckily, while they've been buried,
0:27:08 > 0:27:11their favourite meal has been working hard on its fat reserves
0:27:11 > 0:27:14and some of these will feed the next generation of bears
0:27:14 > 0:27:20continuing to keep our microworld in balance from the top down.
0:27:23 > 0:27:27So this web of interconnectivity in our most northern microworld
0:27:27 > 0:27:30is all dependent on the tiny primary producers
0:27:30 > 0:27:33at the bottom of the food chain that can bounce into life
0:27:33 > 0:27:36and make the most of the returning sunlight.
0:27:42 > 0:27:45But without the specific set of conditions found in Svalbard,
0:27:45 > 0:27:49the primary producers simply couldn't work on the scale they do.
0:27:51 > 0:27:55And without them, one of the most productive areas in the world
0:27:55 > 0:27:57could not exist.
0:28:04 > 0:28:07Svalbard shows us on a massive scale
0:28:07 > 0:28:12the fundamental principal of how microworlds work.
0:28:12 > 0:28:16It is not only the creatures that live in them that make them tick,
0:28:16 > 0:28:20it's also the processes that shape our entire Earth.
0:28:33 > 0:28:36Subtitles by Red Bee Media Ltd