Islands in the Humboldt Stream

Geographically the Galapagos archipelago is on the equator, but meteorologically the equatorial and tropical climate is pushed and washed away by the Humboldt Current which brings with it cold water, gloomy weather, and also the magic of the Galapagos.

In circling the Earth, the equator passes through the magnificent coral reefs of the Maldives and the atolls of the Gilbert Islands in the Pacific Ocean. On the islands of Sumatra and Borneo it crosses the dense tropical jungles and on the islands of Principe and Sao Tome to the west of Africa white beaches with coconut trees and cocoa plantations.

Warm waters, colorful coral reefs, tropical rainforests - all these characterize most groups of oceanic islands along the equator. Only in the Galapagos Islands does the equator meet in arid islands, with little vegetation, with sullen winds and cold air, and a water temperature that falls far below what is common in all other groups of equatorial islands.

Geographically the Galapagos archipelago is on the equator, but meteorologically the equatorial and tropical climate is pushed and washed away by the Humboldt Current which brings with it cold water, gloomy weather, and also the magic of the Galapagos.

The Galapagos archipelago is a group of islands of volcanic origin in the Pacific Ocean, about 1,000 kilometers west of the coast of South America. The islands that make it up are located between the latitudes '40°1 North and '36°1 South - on both sides of the equator: some in the northern hemisphere, some in the southern hemisphere, and the island of Isabella which is right on the equator.

The Galapagos Islands are famous not only because of the unique and fascinating animals that live there, but no less because of the impressions and records of the naturalist Charles Darwin, who visited the islands in 1835 as the naturalist of the expedition and as a companion of Captain Fitzroy. In fact, it was Darwin's impressions of the Galapagos Islands that laid the foundations for the theory of evolution that he later formulated and developed, and published in his book "The Origin of Species" in 1859. "The enchanted islands," he wrote in his diary, "were the source of all my views."

At first glance, even Darwin was a little put off by the uninviting appearance of the islands: black lava and dramatic cliffs are geologically fascinating, but not necessarily an optimal habitat for a great wealth of tropical animal species, as expected from a group of equatorial islands. But soon Darwin's curiosity was aroused by the sight of the giant tortoise, which he did not recognize as such before, and even more so when he discovered that the tortoises differ in appearance and behavior from island to island. He discovered that the inhabitants of the islands know how to distinguish, based on the appearance of the turtle, which island it is from and belong to.

Similar to the turtles, so too are the species of falcons - small songbirds that are common on the islands. 13 different species of Pharisee were recorded by him, and each species existed on a different island, and had different characteristics that suited it to exist on that island. More than the turtles, finches are identified with the enunciation of the theory of the origin of species by Charles Darwin, and they are usually called "Darwin's finches" (Darwin's finches in Laz). He later wrote that those "very interesting" (in his words) birds may have provided part of the answer to what he called "that mystery of all mysteries - the first appearance of new creatures on earth."

If looking above the surface of the water it is easy to notice that these islands are quite different from the typical height of equatorial islands, then looking under the water you can get a hint as to the reason for this.

Instead of clear water, colorful coral reefs and a spectacular wealth of species of fish and invertebrates, underwater in the Galapagos you see dark and opaque water, rich in nutrients, that support huge masses of animals: huge schools of fish, swarms of plankton, gatherings of sharks and more. While richness in different species is a prominent general characteristic of coral reefs, richness in nutrients and large masses of animals that it brings with it are characteristics of cold, temperate and even polar waters.

For this reason, for example, most of the large whales, which migrate in the oceans, spend the summer in the poles, which are rich in nutrients while gathering food to build an insulating layer of fat, while they spend the winter in the warm and pleasant, but poor in food, tropical waters - a good time for breeding.

So what brings cold, nourishing water from the pole to the equator? In the Galapagos Islands a number of central currents converge, but for the sake of abstraction it can be said that against the warm and clear water brought by the equatorial current, the cold Humboldt current rushes from the south, which rises all the way from Antarctica, along the coasts of South America and parallel to them, and around the Galapagos Islands rises from the depths and reaches the surface.

The source of the current is in the Southern Ocean near Antarctica. In its southern part, the Humboldt Current flows at depth, but on its way north, a combination of factors results in a phenomenon called upwelling in English, and in Hebrew "upwelling": the trade winds, in combination with the Coriolis effect (the effect of the tilt of the earth's rotation), cause the upper layer of sea water to move from the coasts towards from across the sea. The heavier water of the Humboldt Current rises from the depths to fill the void. Around the 4° South latitude, near the equator, the Humboldt Current turns west, and there, in the Galapagos Islands region, it meets the warm equatorial current and creates one of the most interesting phenomena in the oceans. The cold and green waters from the south meet the clear blue waters of the equator and create eddies, foam and murmurs. From here the current continues under the name "South Equatorial Current" to the western Pacific Ocean, New Guinea and Australia.

Stream water is 8°C colder than ocean water at the same latitudes. The cold water also cools the air. The low temperatures cause frequent fogs on the one hand, and a stoppage of rains on the other, due to a meteorological phenomenon called "inversion". The Humboldt Current is the direct cause of the formation of the driest desert in the world, the coastal desert of Chile - the Atacama - as well as the desert climate that prevails along the Peruvian coast.

The Galapagos Islands are affected by the Humboldt Current mainly between the months of June and November, the cold and dry season. So it causes a drop in temperature and low cloudiness that covers the surface of the sky most of the day and only a light drizzle comes down in the mountains.

Another cold current that affects the archipelago, mainly on their western side, is the Cromwell Current, which comes from the depths and brings up cold water from the depths to the surface.

The polar water that reaches the north with the help of the Humboldt Current is, as mentioned, cold and rich in nutrients. Such water supports a huge biomass of zooplankton, tiny creatures - crustaceans and various invertebrates - that live in the water and, in turn, constitute a lot of food for many fish and marine mammals. The low temperatures do not allow the existence of coral reefs, which need warm water all year round, and in any case the rich composition of the water makes them impervious to the sun's rays, which are also essential for the development of the reef.

For this reason, the underwater animal society in the Galapagos abounds with huge shoals of fish, large animals - sharks and marine mammals - and even animals typical of temperate and polar regions such as sea lions and penguins.

In terms of the current regime and climate conditions on the islands, it is impossible not to mention the El Niño phenomenon, which occurs right in the Galapagos region, but its influence is evident in large areas of the Pacific, Atlantic and Indian oceans.

The reason for the name of the phenomenon - "the child", in Spanish - is that it occurs near Christmas, which marks the birth of the Christian Jesus. El Nino occurs once every few years and usually lasts about a month, but once every few years, in an inexplicable way, it extends beyond the normal period and causes the temperature of the sea water to rise for a long time, resulting in mass mortality for fish and animals that feed on them. In fact, researchers predict that the El Nino of 2010, at the end of the year, will be stronger than usual, and we are expected to learn about its effects at the beginning of 2011.

The effect of El Niño is also evident on land and to a large extent dictates the pace of life in the west of the South American continent: brutal floods sweep the slopes of the Andes and sweep away entire villages with them. If that's not enough, there is serious damage to the fish harvest from the sea, the dead fish wash up on the shores and rot there, bringing diseases with them and until the villages recover and come back to life, sometimes the next El Nino is already on the way.

Coincidentally, just as the Humboldt Current has a decisive influence on the climate, fauna and flora in the Galapagos Islands, so the writings of the German researcher Alexander von Humboldt, who discovered this current during his travels on the South American continent, influenced Charles Darwin before he set out on his journey. The descriptions of exotic landscapes, animals and natural phenomena that Humboldt described in his writings ignited Darwin's imagination and perhaps influenced his decision to embark on the famous voyage with the research ship "Beagle".

And just as Humboldt's writings ignited Darwin's imagination before he set off on his journey, so are Darwin's impressions and legacy on the islands, they are part of what attracts travelers and nature lovers to the islands to this day, including the writer of these lines.

On one of my walks on the basalt beaches, between the groups of marine iguanas and dense mats of red rock crabs, I aimed my camera at a reddish lava lizard, which was standing on top of a small rock. While standing like that motionless, a tiny bird landed on my shoulders. just like that. I remembered that Darwin described the degree of indifference of the winged people in the islands, by noting that he could "push off the branch they were sitting on with the tip of a gun." I didn't have time to distinguish who the bird was that rested on my shoulder, as it quickly moved away, but my basic assumption was that it was one of the Darwin freaks, who are known for seeing humans as a completely harmless factor, as if we were one of the common giants on the islands.

The giant tortoise is probably the animal most associated with the Galapagos Islands. In fact, indirectly, they are the ones who gave the islands their name: in ancient Spanish Galapagos was a kind of saddle, while the shape of the turtles' shells reminded the Spaniards of the shape of the saddle. This is how the term "Galapago" was coined in reference to the giant tortoises of the islands, and therefore the islands were nicknamed the "Galapagos Islands".

Galapagos tortoises live on seven islands, and are divided into 10 different subspecies, after two subspecies became extinct in recent years. Out of these ten, one species is also doomed to extinction, because today it has a single representative left, who was named "Lonely George" and is considered the rarest animal in the world. Multiple attempts were made to mate George with females of a closely related subspecies, and after much persuasion George mated with two of them. The first spawn gave birth to infertile eggs, but these days more attempts are being made and they hope for another spawn that will yield fertile eggs and from which hatchlings carrying George's genes will hatch.

Galapagos tortoises are considered to be the largest tortoises in the world, large but only slightly larger than the giants of the Aldabra Islands in the Seychelles. An adult turtle may reach a weight of over 300 kg, and a length of 1.2 meters. The average lifespan of Galapagos tortoises is extended by about 100-150 years, but in captivity they can reach much longer: Harriet, another famous tortoise, was apparently Darwin's companion on his way back to England, in 1835. A tortoise was among the animals that Darwin Collected and brought Haim to his homeland, and was later transferred to her home in Australia. Doubts exist as to whether it was actually Darwin who collected Harriet, or whether she was later collected by other visitors to the islands. One way or another, her age at the time of her death in 2006 is estimated to be about 175 years, and she is not even the oldest turtle in the world: Tui Melila, a turtle from Madagascar, was given as a gift to the King of the Tonga Islands by none other than Captain James Cook, and her age at the time of her death (1965 ) estimated at about 188 years!

Another animal that is strongly associated with the islands, and is even more unique because it has no counterpart anywhere else in the world, is the marine iguana.
Darwin described them in his writings: "They are black like the porous rocks on which they crawl and chase their prey from the sea. I call them the 'dark elves'. They undoubtedly suit their living area."
In the Galápagos there are also land iguanas, larger than the marine iguana, but the latter is more common and more unique, because of its affinity with life in the sea. It is said to be the only marine lizard in the world. There are other lizards that benefit from swimming, such as the Komodo dragon in Indonesia, the largest lizard in the world. However, the huge power of Komodo ("the dragon") does not hunt in water, does not dive for extended periods of time, and uses the ability to swim only to transport itself from island to island.

Compared to him and compared to other swimming lizards, the life of the marine iguana involves the sea. It feeds on green algae found on the rocks in the area of ​​the pillow up to a depth of about 20 m. In her underwater forays to collect food, she is able to hold her breath for periods of time of about an hour or more.

When they are not feeding, they lie on the black lava rocks densely, regulating their body heat with the heat of the sun.

But iguanas and turtles also exist in other tropical islands in the world and it is not surprising to discover them in the Galapagos Islands. In contrast, animals such as sea lions and penguins are unusual in the equatorial landscape. The Galapagos penguin is the northernmost penguin in the world, and the only one that also lives north of the equator. They are found mainly on the Fernandina Islands and western Isabela Island, which receive cold water with the aid of the Cromwell Current, but small populations are also found on the main islands. During the day they hunt minnows in the cool water, and at night they come to land.

As far as the winged animals that live on the islands, Galapagos is really a feast for the eyes. The blue footed boobies, also one of the icons associated with the islands, amuse with their clumsy courtship dance, and with both aerial and marine acrobatics, while they dive to a considerable depth in order to eat a juicy fish. But a virtuoso who does not fall off the sole is the frigate, who, although she does not know how to dive in the sea to catch fish, but knows very well how to dive in the air to capture the fish from the mouths of the unfortunate soles, which were snatched from them by a bigger and stronger chicken. Frigates have their own spectacular courtship display - during the courtship season the males inflate a red bag in their chest, and look like they have an inflated football on the front of their neck, under their head.

Many other birds live on the islands, which is a short story from Latarn, but we must also mention the flightless cormorant, the Galapagos albatross which is the largest seabird in the world, the Galapagos pigeon, the Galapagos eagles, the lovable seashells that walk on the beach, and many others.

Darwin's Pharisees may not be spectacular, but their historical importance is great. These are nothing but small songbirds, their size is the size of a sparrow and their colors are not prominent. Darwin noticed that, despite the similarity between them, there are 13 types that differ from each other in the size and shape of the beak, and accordingly, in their diet and their habitats. Darwin described these 13 types and determined that they belonged to different species. In a similar way, he divided the Galapagos tortoise into different types that are close to each other, and considered them different subspecies. Later he came up with the idea that all the Pharisee types evolved from a single ancestor, who came here in the past from the South American continent, and similarly concluded about the turtle types.

Darwin noticed the fact that many organisms have a large number of offspring that differ somewhat from each other. Only some of these offspring survive and reach adulthood. Why did some offspring survive and others die?

For a long time, Darwin was preoccupied with the issue of survival, and finally came to the idea of ​​natural selection. This idea means that there is an existential struggle between different individuals of animals in the population, and in this struggle the fit individuals survive - that is, those that are optimally suited to their environment - while the others fail to exist and die, or fail to produce offspring.

In contrast to the information that was prevalent in Darwin's time, which believed that an animal changes according to its environment during its life and bequeaths these changes to its offspring and thus the nature of the species slowly changes and adapts itself to the environment, Darwin took a different view: those who are born with high competence values ​​and adapt to their environment will survive, and those who are not equipped from birth with adequate competence, will not be able to exist. Over time the original population will go and change, and thus different species and new types will develop. This was the case in the Galapagos Islands, according to Darwin's hypotheses. The differences between the islands may not be great, but the different environment of each island is enough to feel the differentiation process that leads to the creation of new subspecies and species, each typical of its special environment.

In 1835, Darwin returned from his journey on the "Beagle", but did not publish his theory publicly until 1859, some 24 years later. The reason for this delay is unclear. He may have feared the church's reaction to the theory of the origin of species, which was considered heresy in religion. Indeed, his conclusions, when published, created a huge public uproar in Britain. Darwin was accused of uttering heretical words and harming the values ​​of the church and religious faith. The idea that we, humans, were the descendants of a primitive ape and were not created in the image of God, upset many. Strange as it may sound, even today this idea, which is based on evolution, is not accepted in significant parts of the Western world. In many populations in the world, religious belief pushes aside the scientific recognition required of Darwin's theory, which helps us to understand our world and the processes taking place in it much better.

Unlike those places where the theory of evolution is not a consensus, in the Galapagos Islands, as well as among the scientific world, Darwin's legacy is evident in every corner. At the Darwin Research Station in the town of Puerto Ayora, studies are conducted on the animal populations that exist on the islands, monitoring the impact of species introduced by man on the islands and monitoring the effects of fishing, tourism and other human factors on the future of the islands. And really, since Darwin was in the islands, many species have reached the brink of extinction, or an indirect threat to their existence. During the last 30 years, the islands have been recognized as a national park for everything, and hunting and damage to the natural values ​​are prohibited. With over 20,000 visitors each year, it is unlikely that the wild and magical nature of the Galapagos will remain as it is in the years to come, without constant efforts and sufficient resources to conserve, monitor and restore where needed.

There is no doubt that such a unique place must be preserved at all costs, so that we can continue to enjoy the wonderful beauty of nature, and that our children can also enjoy the magic that the Humboldt current brings with it, the magic of the Galapagos.

Amir Gur is a marine biologist and diving tour guide, manager of a content site about the Galapagos Islands and a site about diving in Malta

http://www.galapagosite.com
http://maltasite.info/?page_id=16