A fart is radioactive

Have krill stocks increased in the polar regions since hunting depleted the whale stocks?
Hero Feenders, Bremen

It is true that whale populations had declined sharply in the decades up to the end of commercial whaling around 1964. In the Southern Ocean alone, up to 45,000 whales have been slaughtered annually since 1904. In the meantime the trend has reversed, at least for minke and humpback whales, less so for blue whales. "Nevertheless, the krill stocks have not increased due to the decimation of their predators," says Dr. Volker Siegel from the Hamburg Heinrich von Thünen Institute for Sea Fisheries. Whether this is due to the growing penguin and seal populations, some of which also live from krill? Dr. Bettina Meyer from the Alfred Wegener Institute in Bremerhaven doubts this, because then the krill stocks would have had to decline due to the increase in whales in recent decades. But there is no evidence for this. “The decrease in krill found in long-term data is associated with climate change. Higher temperatures have decimated the pack ice areas under which the krill offspring develop over the winter. ”It is conceivable that it is not whales and other predators that control the krill stocks, but, conversely, that their stocks are determined by the size of the krill prey stock.

Do whales have to fart?
Lou Uschkureit, 10 years

Yes, whales also fart from time to time to get rid of excess gases that are produced during digestion. All whales have to dive and hydrogen, methane and carbon dioxide are more of a hindrance in the gastrointestinal area. The gases are released under water and, since they partly consist of digestion gases, can also have an unpleasant smell. What sounds can produce whale flatulence has not yet been scientifically investigated, unlike with herrings. Scientists have already checked their flatulence for pitch, length and frequency and suggested that they could be used for communication. What has already been researched in more detail from the digestive tract of marine mammals is their intestinal flora. Scientists came to the surprising conclusion that the bacterial community in the intestines of baleen whales is similar to that of both carnivores and herbivores on land. Since they mainly feed on small crustaceans, krill, one would have expected a microbiome similar to that of carnivores. The parallels with ruminants might be helpful in digesting the chitinous krill shells.

Whale strandings Australia

Why are so many whales stranding off Australia?
Ute von Schilcher, Bremen

Interestingly, most of the whale strandings recorded in Australia occur in the narrowly demarcated area between Circular Head and Macquarie Harbor on the island of Tasmania. Most common minke right whales, common dolphins, sperm and pilot whales strand; the latter often in groups. So in 1992, when 198 pilot whales ran into distress near the village of Bicheno. Most strandings are observed in the summer months.

It is unclear whether this is related to growing disruptions from tourism or the habits of the animals. It is also largely unclear why the marine mammals get stranded in the first place. While the Romans still believed that whale stranding was a punishment from the sea god Neptune, other aspects are discussed today. Every now and then it happens that dying or recently died whales are carried onto the beach by currents. Many of the stranded whales were diagnosed with an infection of the inner ear, which could have impaired the animals' navigation skills based on acoustic signals.

Researchers have recently found that some of the areas where whale strandings occur are similar in that the lines of the Earth's magnetic field run directly towards the coast. Since whales presumably orient themselves by means of the magnetic field, it is possible that these lines lead them directly to perdition. The magnetic field changes slowly but constantly, so that once safe hiking routes can now end in certain death.

It can also happen that pilot whales visit calmer shallow water zones near the coast when the sea is rough. If a single animal then runs up and makes "calls for help", this can drive the whole school to ruin, as the socially inclined conspecifics try to stay in contact with the victim. The only way to help is by finding the leader as quickly as possible and dragging it into deeper water. Otherwise, animals that have already been rescued try again and again to follow their lead animal lying on the beach. In addition, whales sometimes seem to have problems locating them when the sea floor rises very gently towards the shore.

In the North Sea, for the sperm whale strandings that occur more frequently here, it is discussed that the noise pollution from oil drilling platforms, the search for raw materials and shipping interferes with the acoustic orientation of the whales. If the male sperm whale turns wrongly into the North Sea on their way from the rich fishing grounds of Norway, they often cannot find their way out. They are pure deep-sea animals whose sense of sound localization does not identify the soft sediments of the shallow Wadden Sea as a danger. As a result, they often swim straight to their doom, believing they are in safe, deep waters.

Finally, whales can be confused when they get into bays that are only connected to the open sea by a narrow channel. Given the apparent hopelessness, the animals can panic and get stranded. Observations and evaluations by Tasmanian conservationists suggest that a combination of the factors mentioned is responsible for individual whale strandings. Only one thing seems certain: that whales commit suicide belongs in the category of sailor's thread.

Whale strandings New Zealand

Why do so many whales keep stranding in certain places in New Zealand?
Rosemarie Acker, Hamburg

Certain New Zealand bays and shallow beaches have gained notoriety. In Golden and Hawkes Bay or on the Chatham Islands, up to 1,000 mostly healthy pilot whales, killer whales, sperm whales and, more rarely, beaked whales or dolphins are regularly stranded. "Of more than 9,000 pilot whales in 207 stranding in the last few decades, only 2,000 animals could be driven back into the water in time," says Dr. Stefan Bräger from the German Maritime Museum in Stralsund. The species mentioned prefer the open ocean and often dive hundreds of meters deep. Closed bays and shallow tidal coasts presumably overwhelm your ability to orient yourself. "The exact cause of the mass strandings is still unclear," says the Stralsund expert. “It used to be assumed that parasites in the inner ear or local anomalies in the earth's magnetic field could trigger a misorientation. At least the latter could be ruled out after measurements at the most common beaching sites in New Zealand. ”In any case, these species live in large groups. If an animal is stranded, the others will not abandon it. This often leads to all of the animals in the association lying dying on the beach.
When and how did the water come to earth?
Helmut Braun, Ortisei

In the dark geological age of the Hadean (based on the Greek underworld Hades) 4.6 billion years to 4.0 billion years ago, the earth was more like the moon than our blue planet: its surface was furrowed by craters and continents did not yet exist. At some point in this age water came to earth. Using the oldest rocks, geologists were able to prove that liquid water existed on young earth 4.03 billion years ago. What was before remains uncertain. The origin of the water has not yet been fully clarified either. There are two theories here: water could have been gassed from the interior of the earth via the then numerous volcanoes. As the earth cooled down, the water vapor collected in the atmosphere condensed and it rained for several thousand years. This created a primordial ocean from which the continents would later emerge. A second possibility for the origin of the liquid water are comets that collided with the earth and in the process also released water vapor. Whether we owe our water to one of these two processes or to both has not yet been fully clarified.
Why are bodies of water quieter at night than during the day?

The sun provides us with energy. Its light and warmth allow plants to grow, winds blow and seas move. It creates pressure differences in the atmosphere that allow air to flow from places of high pressure to places of low pressure: wind comes up. In addition to large-scale and long-term wind systems such as the trade winds, the air also reacts to rapid local changes, for example when a cloud moves in front of the sun.

We can all feel the difference on our skin. The fact that the land warms up faster than the water also moves the air and thus the water: Warm and therefore light air rises over the land. Air flows in from the lake or large bodies of water. At night, the effect is reversed: Then the wind blows in the direction of the water, as it cools down more slowly than the earth. This offshore wind is weaker than more onshore and less noticeable due to coastal cover. The winds blow less at night and therefore move the water less.
In the summer of 2003 it rained very little all over Europe. Many rivers and lakes suffered from low water. Where did all the water go?
Florian Schalk, by email

It is not possible to say exactly where the water that has evaporated in the hot months has rained off, but other factors are also important for the low water levels drastically reduce the source regions of the low mountain ranges ", explains Prof. Uwe Grünewald, hydrologist at the University of Cottbus. "As a result, little meltwater flowed into the surface lakes and reservoirs in the spring of 2003, and the formation of new groundwater was also low."
As in the years 1904 to 1912 or at the beginning of the 1950s, all the prerequisites for the low water levels that often occur on the Elbe in summer were in place. The situation on the Rhine is completely different. It rises in the high Alps, where masses of snow and glaciers provide water supplies in spring and summer. No wonder, then, that the annual discharge of the 1,320-kilometer-long Rhine, at 69 cubic kilometers, is almost three times as high as that of the 1,140-kilometer-long Elbe, where only 24 cubic kilometers go down the "brook".
However, if - as in the summer of 2003 - the usual rainfall at the time of the year does not occur, Father Rhine is not immune to falling water levels. Even more: In the context of global warming and dwindling alpine glaciers, the water flow of the Rhine could match that of the Elbe in the coming decades. More frequent water level lows would be the inevitable consequence.
Which is the busiest waterway in the world?
Peter König, Bremen

The phrase “the most traveled waterway in the world” is often found in sailing and shipping literature. This means sometimes the English Channel, sometimes the Strait of Gibraltar, then again the Malacca Strait between Malaysia and the Indonesian island of Sumatra, which is notorious for its frequent pirate attacks. In fact, it is impossible to decide which of these natural sea routes is the most frequented. Statistics are only kept for artificial waterways and for ports. The Waterways and Shipping Directorate North helped us with the following figures for 2005. The Kiel Canal ranks first with 42,552 ship passages per year. The Suez Canal with 18,193 and the Panama Canal with 12,647 ships take second and third place.

However, if you take the tonnage as a basis, the whole thing looks very different. The Suez Canal clearly leads there with 671.8 million tons, followed by the Panama Canal with 278.3 million tons and the Kiel Canal with only 88.2 million tons. This is due to the different sizes of ships that the canals can use. The Suez Canal has no locks - the ships are only limited by their draft (almost 19 meters) and a maximum tonnage. With a maximum ship size of 294 meters and a draft of 12 meters, the Panama Canal is impassable for 60% of all merchant ships. The Kiel Canal, on the other hand, can only be used by ships with a maximum length of 235 meters. With a draft of 9.50, they may even be only 160 meters long.

As for natural sea routes, the Malacca Straits, the main link between the Indian Ocean and the South China Sea, actually appears to be the busiest. Port statistics offer good indicators for this. At the south-eastern exit of the waterway, Singapore is the second largest port in the world after transshipment. In 2006 alone, around 448 million goods were handled here, a good part of which was certainly transported through the Malacca Strait.