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Hydrothermal vent fauna. Photo Credit: NOAA Okeanos Explorer Programme.

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5 Deep-Sea Habitats: Highlighting the Diversity of the Arctic Ocean

Explore the distinct landscapes of the Arctic Deep…

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During our recent Arctic Deep 2024 expedition, we collected vast samples that reveal the incredible array of deep-sea organisms, as well as the diversity of underwater habitats.

From extraordinary fish to unique invertebrates, our findings showcase the resilience of life in one of the most extreme marine ecosystems on Earth. These samples will be further explored at our Arctic Taxonomic Workshop, where scientists will collaborate to identify and classify these remarkable creatures, enriching our understanding of Arctic marine biodiversity.

When discussing the depths we’re exploring, we’re looking at regions that can extend to 6,000 metres, far beyond the reach of sunlight, where conditions are incredibly challenging, often requiring specialised submersibles designed to withstand the immense pressure and cold of the deep ocean.

Featured Image Credits: NOAA Ocean Exploration

MID OCEAN RIDGES

Mid-ocean ridges are vast underwater mountain ranges and deep-sea habitats that can stretch for 60,000km. These have been created by the interactions of the earth’s tectonic plates, forming new oceanic crust as magma rises to the surface. These ridges are some of the most geologically active regions on Earth.

One example is the Knipovich Ridge in the Arctic Ocean, an area explored during the Ocean Census expedition. The Knipovich Ridge is particularly fascinating due to its slow-spreading tectonic activity. Life around this ridge thrives in extreme conditions, with organisms adapted to survive near hydrothermal vents and cold seeps, including deep-sea corals, chemosynthetic ecosystems, and endemic species of benthic fauna.

Mid-ocean ridges like Knipovich not only play a crucial role in Earth’s geological processes but also harbour ecosystems that help scientists understand biodiversity in extreme environments and the impact of deep-sea life on global ocean health.

Aerial view of Arctic deep-sea habitat showing mid-ocean ridges and surrounding landmasses.

Image credits: Google Maps

HYDROTHERMAL VENTS

Hydrothermal vents are fascinating deep-sea habitats, like those found in the Jøtul Field of the Arctic deep sea, where superheated, mineral-rich water emerges from cracks in the ocean floor, often near volcanic or tectonic activity.

These vents are typically found at depths of 2,000 to 4,000 metres along mid-ocean ridges, where the Earth’s tectonic plates are moving apart. The water, heated to temperatures as high as 400°C, interacts with surrounding rocks and becomes enriched with chemicals such as hydrogen sulphide.

Unlike most ecosystems that rely on sunlight for energy, hydrothermal vent communities depend on chemosynthesis, a process where microbes convert these chemicals into energy. This forms the foundation of a unique food web, supporting chemosynthetic species like bacteria, which in turn give energy to a wide range of species of tube worms, gastropods, isopods, sea spiders, and specialised fish.

In places like the Jøtul Field, the Arctic environment adds another layer of challenge, with its icy waters and intense pressures. Despite these extremes, these vents host diverse ecosystems, much of which remains unexplored.

Hydrothermal vent in a deep-sea habitat emitting dark, mineral-rich water from the ocean floor.

Image Credits: REV Ocean

COLD SEEPS

Cold seeps, like those found near the Svyatogor Ridge during the Arctic Deep expedition, are unique deep-sea habitats that do not emit superheated water as hydrothermal vents do, but instead release methane at much lower temperatures. Despite the cold and extreme conditions, these habitats support thriving communities of organisms.

Cold seeps are often found near continental margins or areas with tectonic activity, like mid ocean ridges. The ecosystems here are slower-growing than those at hydrothermal vents, but they are equally vital in helping scientists understand the deep ocean’s biodiversity and geochemical cycles.

Studying cold seeps provides insight into carbon storage, methane cycling, and the adaptation of life to extreme environments, all of which have important implications for both ecology and climate science.

Topographic map of Svyatogor Ridge, illustrating deep-sea habitats near tectonic features in the Arctic Ocean.

Image Credits: C. Argentino, C. Borrelli, A. Akinselure, M. et al. https://doi.org/10.1016/j.marpetgeo.2024.106761

ABYSSAL PLAINS

Abyssal plains are vast, flat deep-sea habitats, typically found at depths between 3,000 and 6,000 metres. These plains are covered in fine sediments that have slowly accumulated from the remains of marine organisms, volcanic ash, and dust from the atmosphere.

These environments are home to a diverse range of specially adapted life forms, such as deep-sea fish, worms, sea cucumbers, and microorganisms.

The ecosystems in abyssal plains rely on “marine snow”, a steady drift of organic matter falling from upper ocean layers, as a primary source of food. These plains also play a crucial role in global geochemical cycles, acting as storage zones for carbon and other elements.

DEEP WATER COLUMN

Although sampling the water column was not our main focus on the Arctic Deep expedition, it still provided incredible insights from the ROV Aurora.

The deep water column refers to the vertical zone of ocean water that extends from just below the surface layer to the abyssal depths, often reaching several thousand metres. The deep water column is characterised by complete darkness, cold temperatures, and increasing pressure as depth increases.

Life here has evolved remarkable adaptations to survive in these extreme conditions. Organisms such as fish, squid, and jellyfish are common, using bioluminescent abilities to navigate, hunt, and avoid predators in the dark.

The deep water column plays a critical role in global nutrient cycling, carbon storage, and the ocean’s overall health. Despite its vastness, much of this zone remains unexplored, offering enormous potential for scientific discovery.

 

Keep up to date with all of our findings from the Arctic Deep workshop (October 2024) by following The Ocean Census on our socials.

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