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Small animals across the ocean

  Bryozoans, date mussels, sea squirts… more and more species are quietly boarding the ship and wandering around the world. This could lead to an ecological disaster, the researchers warn.
  The problem may be as old as sea travel: For centuries, ships and crews have transported not only cargo but also inadvertently diverse species of plants and animals to distant lands.
  In 2019, scientists discovered 53 new species in the waters around the Galapagos Islands, the largest increase of alien species ever reported in tropical waters. In addition to sea squirts, these alien invaders include spaghetti bryozoans, notorious for attacking piers and fishing gear, and date mussels, which burrow into archipelago corals in large numbers. Almost all of the new species were inadvertently brought in by ships from other tropical waters, the research team wrote in the professional journal Aquatic Invasions.
  According to the International Maritime Organization, ships currently carry 80 percent of the world’s freight. In the professional journal Nature Sustainability, a research team led by Brian Leung of McGill University in Canada warns that increased shipping volumes may pose a greater threat to marine biodiversity than climate change. Many organisms will travel around with the hull or ballast water, and then conquer new habitats, threatening native species.
  ”Our research shows that unless appropriate action is taken, such invasions can grow exponentially, with potentially large economic and environmental consequences,” said Anthony Sadan, from the research team at McGill University. “By 2050 Depending on the development of the global economy, the risk of alien species introduced by ships could increase by a factor of 3 to 20 in 2019.”
  Seagoing ships rely on ballast water in their tanks to balance different loading conditions and stay upright: a ship needs a lot of ballast water when it’s loaded with little or no load, and little or no ballast water when it’s fully loaded . In the past, water was pumped from port tanks into ballast tanks when unloading cargo, and ships were drained when loading. Creatures of all kinds—from bacteria and plankton to jellyfish and crabs—follow the water from port to port, sometimes traveling halfway around the world. Most of them die along the way, but quite a few survive and settle in new habitats. In Germany, the most famous example is the Chinese mitten crab (commonly known as “hairy crab”). They were first discovered in Germany at the beginning of the 20th century, probably arrived here as a juvenile stage via ballast water, and have since spread in various German rivers.
  Fishermen in the Black Sea and the Sea of ​​Azov have a deep understanding of the economic loss and social impact of species brought by ships. American ctenophores, which came here via ship ballast water, multiplied rapidly and devoured plankton, the food of many sea dwellers, thus changing the local ecosystem and causing a sharp decline in fish populations. According to the International Maritime Organization’s website, comb jellyfish invasions are the main cause of the destruction of fisheries in the Sea of ​​Azov and the Black Sea. In recent years, comb jellies have also made their homes in the Baltic and North Seas. In addition, viruses and bacteria such as Vibrio cholerae, the causative agent of cholera, have also been transmitted by shipping.

  On September 8, 2017, the Ballast Water Management Convention entered into force. As of July 2019, 80 countries, accounting for nearly 81 percent of the world’s merchant shipping tonnage, have joined the convention. The Convention stipulates that older ships need to change their ballast water in the open sea instead of in the port as before. They must be at least 200 nautical miles (about 370 kilometers) from the coast and the water depth must exceed 200 meters. Release as few organisms as possible into coastal or harbor waters. On new or refurbished ships, a ballast water treatment system must be installed to ensure that the ship complies with the various limits for discharged water. In one cubic meter of water there can be no more than ten organisms larger than 50 microns in size. The convention even sets maximum values ​​for the number of bacteria. Such water quality standards are achieved through mechanical methods such as filters, physical methods such as ultraviolet light irradiation, and chemical methods such as ozone or chlorine treatment. From 2024, the standard will apply to all ships of the contracting states.
  For more than a decade, engineer Holger Wattl of the Flensburg University of Applied Sciences in Germany has been researching the cleaning process of ballast water in order to maximize the prevention and control of alien species. Another risk factor for alien species infestation is so-called “hull biofouling”. Many regulations are aimed at controlling this growth, but Vettel believes that the problem is less urgent because biofouling will increase fuel consumption due to increased driving resistance, so it is in their own interest for shipping companies to actively control biofouling.
  Meanwhile, the Galapagos Islands, home to hundreds of thousands of tourists a year, are trying to take another step to control the invasive species: All ships from international waters anchored in larger ports are inspected by divers . If an alien species is found, the vessel must leave port and not return until the hull has been cleaned.

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