top of page
This site was designed with the
.com
website builder. Create your website today.Start Now
Research

Using my deep-dive mindmap I was able to undertake in-depth research into deep-sea trenches. During this research I watched an incredibly useful documentary which has its own notes at the bottom of the page.

Geology

  • Primarily long, narrow rock formations

    • Make up the bottom 45% of the ocean

    • Runs deep into the earth's core, resulting in underwater magma deposits

  • The subduction of the oceanic crust beneath the continental crust can also cause the creation of volcanic arcs, which lay parallel to the trench but is on the surface

  • Evidence of ancient trenches exist

  • Trapped inside the earth's crust, and existed millions of years ago

    • The Farallon Trench – Was created when the pacific plate pushed into the Farallon plate, forcing it to subduct underneath North America’s continental crust

      • Could not create enough new seafloor to prevent it from being absorbed​​​

      • Can be seen using SONAR technologies under the continent

Life forms

  • A lack of natural light means there is zero plant life that is able to grow

    • All animals are carnivores. They either hunt or are bottom feeders

      • Feeding on the waste of other living and other dead fish​

  • Animals are also translucent

    • No need for protection from the sun​

  • Immense pressures mean most fish also depressurise when brought to the surface, which makes it difficult to properly monitor them (such as the Smooth-Headed Blobfish, which actually looks like a "normal" fish in its natural environment)

  • Most animals are either blind or incredibly short-sighted, leaving them to rely on other techniques to navigate

    • Echolocation​

    • ​Specially developed touchpads on their bodies​

  • Examples of animals

    • Halloween-Hued Shrimp

    • Skeletal Jellyfish

    • Coffinfish

    • Vampire Squid

    • Siphonophores

    • Blobfish

    • Giant Amphipods

    • Ghost Fish

    • Anglerfish

    • Goblin Shark

    • Frightening Fangtooth

    • Sabertoothed Viper Fish

Exploration and Mapping

Bathymetry​

  • Bathymetry is the study of underwater terrain

  • Before the use of sonar, they used depth sounding lines (Pre 1900s)

    • A sounding line/lead line is a weighted rope that is thrown into bodies of water to measure their depth

      • Measures in “fathoms”, which is about 1.82 meters

    • Although not accurate by todays standards, was reliable enough to be used as a technique for thousands of years of sailing

    • Used this to measure the entire seafloor, as well as trenches

    • HMS Challenger set off in 1862 with 181 miles / 296km of rope in order to map the surface of Earths oceans

  • Later upgraded to sonar, which bounces sound waves off of surfaces in the ocean to gain an accurate picture of what it looks like

  • Oceanographers are also currently using radar and satellite imaging

Submarines

  • Submarines and Submersible Vehicles are used to explore the deepest points of the trenches

  • The Trieste (1960) and the Deep-Sea Challenger (2012)

    • Both were manned missions to the deepest parts of the ocean

    • Both broke while in the Mariana Trench

      • The Trieste experienced a window crack from the pressure 20 minutes into exploring the floor of Challenger deep​

      • Deep-Sea Challenger suffered a malfunction with its hydralics that rendered it unusable

  • The Tonga Trench, specifically the Horizon Deep, is of interest to marine biologists because of its worm populations, so many deep-sea submersible vehicles (DSSV’s) are sent to its lowest point

    • Also interested in the presence of Amphipods, giant crustaceans found in the trenches.​

Effects of climate change

  • Despite being the deepest points the oceans, evidence of the climate crisis has been found in the trenches

  • A study of the debris found at the bottom of the trenches found man-made rubbers, metals, wood, and plastics

    • 89% of this plastic were fragments or particles of single-use, disposable plastics

    • Plus, an entire plastic bag was found lying at the bottom of Challenger Deep

      • Said to be a bag similar to a plastic shopping bag​

  • This study also revealed that the 2010 BP oil spill is directly responsible for the acidification of the deep ocean

  • In the 1970s tonnes of toxic waste was dumped into the Puerto Rico trench, which later studies showed had damaged large parts of the ecosystem despite scientists believing it was safe at the time

  • Global warming is also affecting the trenches

  • Extreme depths are more susceptible to any temperature, oxygen or PH changes

    • Also absorbs carbon far quicker than the rest of the ocean

      • Between a quarter to a third of all CO2 produced by humans is absorbed into the ocean

      • Embeds into the ocean floor and walls as carbon deposits, where it will remain for millions of years

      • Carbon absorbs heat, and there is evidence to suggest that the increase of carbon in the ocean can be linked with the rapid increase of heat in the water

Documentary - Deep Ocean: Descent into the Mariana Trench (2017)

Whilst researching I came across this documentary, which is narrated by David Attenborough. It focuses on scientific teams exploring the Mariana Trench, and was even able to capture some of the discoveries they made first-hand. Below are the of the notes I made:

  • Most sea life lives past 1000m

  • Some are bioluminescent

  • Pressure is 1000x that of the surface

  • Was previously assumed the deep waters were barren and incompatible with life

  • Animals are carnivores

  • Most of the creatures bodies are made up of water

    • Water is incompressible, so isn't affected by the pressure​

    • Hadal Zone - Depth at which the pressure crushes the cells in a body

      • Life is not possible for the vast majority of creatures​

  • Scientists attached a camera to a rod of bait and lowered it to the sea floor

    • Was completely swarmed with giant amphipods​

      • Stripped the fish to the bones​

    • Later, a Mariana Snailfish was caught on camera

      • Lowest point a "fish" has ever been seen​

      • Special sensory pods on underneath of mouth to detect movements in the water

  • Scientists then decided they wanted to catch a Snailfish so they can study it

    • Set up a cage trap​

      • Was able to capture Supergiant Amphipods​

      • Also caught and studied a Snailfish

        • Soft and gelatinous. No scales. Completely transparent​

        • Pores all around mouth, eyes, and "neck"

        • Probably blind

  • More camera footage reveals the Snailfish feeds on Amphipods, explaining how it thrives in an area with no other food

    • Amphipods also eat each other (giants eating scavengers)​

      • Scavenger Amphipods eat wood. Have developed a special enzyme to draw nutrition from it​

  • Scientists then release a Remote Operated Vehicle/Submarine (ROV)

    • Found mineral structures resembling stalagmites​

      • Found worms and clams living in the structures​

        • Clams are a new find​

      • Creatures survive here because the minerals release chemicals, which are taken in as nutrition

  • Original Trieste kept in a Navy museum in Washington, showcased by one of the original divers, Don Walsh

    • Believes he saw a flat fish at 11,000 meters​

  • Launch of a new ROV similar to the Deep-Sea Challenger and sent it to below 10,000 meters to the sea floor to find life

    • Found Amphipods​

    • Discovered a new Sea Cucumber, in extremely large numbers

      • Aligned in one direction, implying there is a sea current ​

  • Many of the species of creature found in the trenches are also found in the Antartic

    • Theorised that they travelled from the arctic and evolved relatively recently​

bottom of page