In this section we continue our determined quest to counter claims of ignorance about the “unfathomable” ocean, her ecologies and inhabitants. We try to bring to the surface the myriad ways in which the ocean is fathomable as we also probe the deep limits to that knowledge.
We make no claims that our watery scavenge is comprehensive. After all, a net has holes: they are fabricated of:
, or plastic 
with spaces 
between them, allowing gas, liquid 
, or small objects 
to go throughIn our net, which acts as a guiding figuration, there will be snippets — headlines, reports of scientific studies, everyday encounters, artistic, popular cultures and genres of oceanic representations. Some material will be well known to some and not to others (a quarter of global wild fish capture is pulped to feed farmed fish, or turned into fertiliser, human nutrition supplements, and pet food). Facts about actual nets will also feature — it is estimated that around 48,000 tons of ghost-nets are generated each year. As will artistic activism, for instance the artwork of Torres Strait Islanders who live with the ever-present reality of ghost nets.
This is the zone most known to humans. It is where sandcastles are built in the sand and destroyed by the incoming tide. It is where the sea meets the land – the sand is the product of this union. The mining of beach sand for vast infrastructures such as artificial islands or for the concrete to build yet more buildings is the second largest mining activity in the world. The intertidal zone contains a diversity of creatures that live in the dynamic environment of tidal action – waters crash in and then withdraw erasing human footprints. Oysters, mussels, starfish and tiny crab are amongst the energetic inhabitants of this world. Those that live in this zone deal with being continually immersed in sea water and then exposed to sun and wind.
Purse Seine fishing net closing and trapping the fish to be broad on board. This is a view of the net being run through the powerblock and then laid back on the stern of the fishing vessel.
A large tuna is landed by fishermen working together, Spain, Barbate, 1982.
A floating flipped iceberg in the Weddell Sea, off Argentina, with a block of green sea ice now showing above the water, joined to the whiter land ice.
This picture was taken from the British research vessel RRS Discovery on a research cruise in the Southern Ocean in the Weddell Sea. It shows a flipped iceberg where the dark green sea ice is visible alongside the usual white-blue land ice. This can only be observed very rarely and only close to Antarctica. It is believed that the dark green colour comes from iron dust, coming from the Antarctic continent and then locked in inside the freezing seawater at the bottom of the floating land ice.
Separating shrimp from bycatch, Florida East Coast, 1969.
This photo was taken in the Yucatán Peninsula. We can see the impact of garbage and population growth, which most of the time we normalize and even ignore. I took this picture while collaborating with [a] group of divers on [a] mission to clean and take care of the cenotes. – Nelly Georgina Quijano Duarte
NOAA is forecasting an above-average summer “dead zone” in the Gulf of Mexico covering approximately 5,827 square miles — an area roughly the size of Connecticut. The dead zone, or hypoxic area, is an area of low oxygen that can kill fish and other marine life. It occurs every summer and is primarily a result of excess nutrient pollution from human activities in cities and farm areas throughout the Mississippi-Atchafalaya watershed. The average dead zone measurement is 5,205 square miles over the 37-year period of record.
A diver looks up at an incredible 100-foot-tall kelp forest in cool clear waters at the Channel Islands in the marine sanctuary off the California coast, USA. These fragile feats of nature are what we stand to lose if ocean warming continues uncontrollably. City: Los Angeles. Region: Channel Islands
Fish in a kelp forest, California, Point Lobos State Reserve, 2005.
Scleractinian corals, American Samoa, Rose Atoll.
Bubble coral – Plerogyra sinuosa, Johnston Island, 2012.
Tuna ensnared near the mouth of a fish trap. Depth 25 meters, Italy, Favignana, Sicily, 1999. This tuna weighed 270 kilograms (approximately 600 pounds).
The species people rely on for food are faring even worse – 74% decline in populations of tuna and mackerel.
Synthetic fishing nets take 600 years to breakdown into microplastics and some of the abandoned nets can be as big as football pitches.
One in four species of sharks, rays and skates are now at threat of extinction.
This is the sunlight zone where light energises hugely important yet minuscule creatures. The sunlight allows for photosynthesis. Phytoplankton and micro algae thrive and produce about half of the oxygen we breathe. The unaided human eye can’t see them, yet they are the base of the ocean food web. This area is also polluted by human inhabitation; agricultural pesticides run into the sea, storm water in coastal cities like Sydney flush a wide array of toxins into the harbour.
In the twilight zone life gets very noirish. Fantastical – to us – creatures have evolved in the deep cold dark waters, some producing their own light through bioluminescence. According to experts, “the biomass of fish in the twilight zone may be ten times greater than previously thought—more than in all the rest of the ocean combined.” The greatest migration on our planet happens every night when some species travel from the ocean depths to the surface in what is known as Diel vertical migration (DVM). Feeding themselves and somewhat protected by night, they return to the relatively safe darkness at dawn. In so doing they circulate the nutrients from the depths to the surface. “Marine snow” is also an important source of nutrients. Composed of whale poop, dead phytoplankton and other debris, this falls mainly into the twilight zone where it nourishes life and acts to sequester carbon.
Whale sharks are fish: unlike air-breathing whales and dolphins, they have no physiological need to swim at the surface. Tracking studies undertaken at Ningaloo Marine Park and other international locations indicate that whale sharks can dive to 700 metres and remain away from the surface for long periods.
Sperm Whales Swimming Off Dominica.
Overfishing has put over 1/3 of one-third of all sharks, rays, and chimaera species are at risk of extinction.
Every night, the diel vertical migration sees Earth’s biggest routine biomass migration with estimated 10 billion tons of animals ascending from over 900m depth.
A red flat Spanish dancer sea cucumber (Benthodytes sp.) hovers at 2789 meters water depth, Davidson Seamount, California.
Gold sea urchin (Tromikosoma sp.) at 2932 meters water depth, Davidson Seamount, California.
Yellow Picasso sponge (Staurocalyptus sp.), California, Davidson Seamount, 2002.
The ocean is dark and cold and the pressure would get to us – in the midnight zone it ranges from 100 to 400 atmospheres. There is a lot going on down there, much more than humans know. A huge variety of animals and microbial creatures inhabit this zone and continually consume carbon that has fallen from the surface. Humans don’t know a lot about this zone because it is far down, and remote-operated vehicles (ROVs) are not of great use because their lights alter the life we need to study. However, they are getting increasingly sophisticated at bringing up extraordinary life.
The deeper into the ocean, the less humans know. However, that doesn’t impede the insatiable quest for knowledge, and of the late the greed of some people. The fact that we will run out of land-based mined metals and minerals like cobalt, nickel, aluminum, and manganese to fuel our phones, cars, etc., has propelled the search for them at the bottom of the ocean. This is a fraught issue. The desire to use alternative energy sources to fossil-based ones may be understandable and even laudable but the damage to these deep environments is unthinkable.
Plastic bags and artificial debris are seen in the Japan Trench at a depth of 5347 metres.
The U.S. government estimates that 11 billion barrels of oil and 190 trillion cubic feet of natural gas are ready to be extracted from the floor of South China Seas. Such fossil-fuel reserves, some believe, are fuelling the turmoil increasingly engulfing the region.
“Animals, protists, and bacteria together account for 80% of the marine biomass, whereas on land they comprise only 2%”
Ocean acidity has increased about 25% from preindustrial times to the early 21st century.
Up to 11,000 metres deep, the Hadal zone – named for Hades, the Greek god of the underworld inhabited by the dead – is thought to be the size of Australia though consisting of some 35 trenches spread mainly throughout the Pacific Ocean. First explored in the 1950s by the Danish Galathea and the Soviet Vitjaz expeditions, this vast area is thought to be filled with diverse forms of life. The pressure in these depths is stupendous — like placing one tonne on the end of your finger. As Johanna Weston puts it, previously thought to be desolate, these areas hold an “extraordinary biodiversity”. It is hoped that some of these may provide evidence of physiological processes that may result in new drugs and treatments for medical conditions such as Alzheimer’s disease. The Clarion-Clipperton Zone some 4,500 metres deep, and the Mariana Trench between 10,900 and 11,034 metres deep, are hot spots for DSM (Deep Sea Mining) exploration. The ISA (International Seabed Authority) is very slowly trying to come up with regulations. Until then the rush to mine the Earth’s mantle continues – which we document.