Deep Sea Ecosystems Flashcards
What is the deep sea
Water and sea bed beneath the edge of the continental shelf - deep sea regarded as benthic habitat situated below 200m.
What is bioluminescence
Light produced by a chemical reaction within an organism - below the eupthotic zone ~90% of animals are bioluminescent in the mesopelagic zone.
What two main chemicals are required for bioluminescence
Luciferin creates the light but requires luciferase which catalyses the oxidation of luciferin resulting in light
What is Hydrostatic pressure
Due to weight of overlying water pressure increases by 1 atmosphere every 10m - abyssal plain can be over 500 atmospheres
What is the main impact of hydrostatic pressure on organisms
Compresses gasses including the swim bladders of fish - organisms however have evolved to cope.
What is sediment like generally on the deep sea floor
Soft, fine mud at a greater scale than mid estuaries. - Represents world largest single habitat due to physico-chemical condition consitency
What are the two main classes of deep sea sediments
Biogenic oozes such as Siliceous oozes, and clay particles, inorganic sediments found mainly under oligotrophic surface waters such as mid ocean gyres
What are biogenic oozes
Sediments below surface waters containg >30% biogenic skelatal material
What are the two subclasses are biogenic oozes
Siliceous ooze - Silicon based made of skeletal diatom frustles and radiolarians.
Calcareous (foraminiferan) oozes based on CaCO3 from planktonic foraminifera and coccolithophores.
What does the compostion of deep sea sediments depend on
The productivity of surface waters and species composition - the falling of material from the euphotic zone has major implications on deep sea marine life
What implications do cetaceans have for deep sea habitats
Whales die and fall to sea floor, scavengers remove tissue and bones remain for a long time creating island habitats or high diversity of organisms
What is the chemosynthesis formula
S^2-(sulphide) + CO2 + O2 +H2O –> SO^2-4 + [CH2O] (organic material)
What is Chemosynthesis
A significant microbial process involved in seawater sulphur cycling. Organic matter is consumed by sulphate reducing bacteria, converting sulphates into sulphides - this is then subject to microbial oxygenation resulting in generation of organic compounds.
Where do hydrothermal vents form
Mid ocean ridge expansion zones and subduction zones - associated with high levels of tectonic activity
How are water temperatures that exceed 100C possible at hydrothermal vents
Hydrostatic pressure prevents water from boiling
