LECTURE 10 – WEEK 5: deep-sea biology and deep-seabed mining marine sciences II
SABINE GOLLNER –
○ for the majority of the seafloor, we don’t know what it
THE DEEP SEA looks like (satellites can’t penetrate into the ocean → no
video or photo material)
● our blue planet can be considered as our black planet, since
light does not penetrate deeply in our ocean
○ most abyssal seafloor is 3000-6000 m ABYSSAL PLAINS
○ deep sea is < 200 m (92% of the ocean)
○ 50% of the ocean is below 3000 m ● abyssal plains: areas on the seafloor (4000 m depth)
○ mean depth of the ocean is 3800 m ● abyssal plains are full with polymetallic nodules: mineral
● biomass is highest in the upper 200 m of the ocean, decreases secretions that live in specific parts
in the deeper sea, and shows a slight accumulation near the ● stable ecosystem
ocean floor ○ slow sedimentation rate:
○ T and light decrease with depth ⥽ a few mm per 1000 a (red clay)
⥽ 10-30 mm per 1000 a (oozes)
⥽ several m per 1000 a(close to rivers)
○ sedimentation rate is usually very slow → habitats are
very sensitive to disturbance; organisms aren’t adapted to
major disturbance events
○ future human disturbance by trawling of polymetallic
nodules (growth rate of nodules: 1-4 mm per 1 000 000 a)
● biological pump – deposition on the seafloor
○ food consumed by animals on the deep seafloor originates
from the upper 200 m of the water column
(phytoplankton → zooplankton → sinking particles)
○ 2-4% of the carbon uptake is stored in the seafloor
○ cold, slow sedimentation, little food
● deep sea characteristics
○ lack of light (light diminishes with depth)
○ high pressure (increasing with depth)
○ low temperature (2 °C)
○ stable temperatures
○ weak currents
○ low food availability
● deep sea is more than 1 ecosystem
○ abyssal plains
○ seamounts
○ continental margins (with canyons, cold seeps)
○ whale falls & wood falls
○ mid-ocean ridges (with hydrothermal vents)
DEEP SEA HAS A HIGH BIODIVERSITY
● examples of what the deep seafloor contains; mussel beds,
● Study (2000-2010) shows the number of known marine species
black smokers, shrimp swarms, limpets, abyssal plain (flat
was estimated to be 250.000. Now, it is estimated there are
area), sponges and anemones attached to nodules, nodule
million(s) species in the deep sea.
field, sea cucumbers, dumbo octopuses
○ knowledge is inversely correlated to size class
1
, LECTURE 10 – WEEK 5: deep-sea biology and deep-seabed mining marine sciences II
SABINE GOLLNER –
○ ~5% of the ocean has been systematically explored
○ number of specimens (N), number of species (S)
● deep-sea hydrothermal vents: energy rich, reduced and hot
fluids are venting out of the deep seafloor
○ found along mid-ocean ridges at places where the earth
plates are thin and diverging
● Even though that study is 15 years old, the big questions are ○ cold seawater (2 °C) sinks through cracks through the
similar; How many species are there, and how are they earth crust → water gets heated by the magma chamber
distributed? How big is the area that one species can inhabit, and loses chemicals, and get enriched in other chemicals
and what does that mean to our estimates of species richness (minerals; copper, zinc, iron, sulfur) → hot water (300-400
in the oceans of the world? °C) is pushed through channels where the earth crust is
● biodiversity – there is an unexpected high & hidden diversity finished and gets expelled into the ocean → hot water
of brittlestars (archetypal species) → when you look at gets in contact with the cold seawater → minerals
organisms, they might not be the same species precipitate → formation of black smokers (average size is
● biodiversity – Where do we find which species? 5-10 m)
○ there are more seafloor samples taken in the North Sea ○ mainly iron makes the smokers black
than the Pacific Ocean due to greater number of organism ○ steep gradient between hot water coming out of the black
records in well-studied areas → it’s difficult to draw smoker and cold surrounding seawater (2 °C)
conclusions about biodiversity
○ many deep-sea species are only discovered once
○ of a total of 275 polychaete morphotypes only 1
morphotype was shared among all 5 study areas
⥽ 49% morphotypes were only found in 1 area → show
high biodiversity in the deep sea
● biodiversity – How are populations connected?
○ if you want to study population connectivity, you need at
least 20 specimens of 1 species from 1 place → we don’t
know a lot of connectivity, because we don’t have the
amount of specimens to study it
● summary; food from surface waters, low food availability, low
faunal biomass; high biodiversity
HYDROTHERMAL VENTS (mid-ocean ridges)
● deep sea – energy input
○ deep sea live on abyssal plains are mostly dependent on
food production at the upper 200 m
○ (especially near mid-ocean ridges) there are ecosystems
that receive energy input by hot fluids venting out of the
seafloor by chemosynthesis ● global distribution of hydrothermal vent fields
○ abyssal plains are completely different from hydrothermal ○ mid-ocean ridges; all plates diverging locations
vent ecosystems with chemosynthesis ○ places with thin earth crust and a heat source below
2
, LECTURE 10 – WEEK 5: deep-sea biology and deep-seabed mining marine sciences II
SABINE GOLLNER –
● every vent field is unique at mid-atlantic ridge
○ different structures, biodiversity, community composition,
and dominant species due to biogeographic provinces
● ways of larval dispersal to another vent field by:
1) bottom currents (e.g. limpet larvae)
2) ridge-controlled currents (hydrothermal plume become at
a certain height neutrally buoyant → travel large
distances)
3) ocean currents (e.g. shrimp larvae)
● communities at hydrothermal vents
○ 1st level primary producers (not dependent on light) are
the basis of the food web
⥽ (chemo)autotrophic bacteria
⥽ autotrophic nutritional symbiosis
○ 2nd level primary consumers
⥽ deposit feeders
⥽ suspension feeders
○ 3nd level secondary consumers
⥽ predators
⥽ scavengers
○ organisms have to be adapted to the extreme conditions
of the hydrothermal vents
● unique endemic fauna at active hydrothermal vents is
dependent on chemosynthesis
○ megafaunal organisms (e.g. shrimp, mussel) live in
symbiosis with chemoautotrophic bacteria
● bacteria in symbiosis with macrofauna
○ episymbiotic; bacteria (symbiont) on gills of shrimp
⥽ bacteria on the Pompeii tube ● connectivity in a patchy environment
○ endosymbiosis; bacteria inside the mussel ○ distance needed to ensure connections of larvae
⥽ bacteria in tube worm (Riftia pachyptila); fastest (accounting for currents and larva life span): <150 km
growing animal on earth which is sessile ○ distance between active vent fields typically >150 km
● How is an animal taking up symbionts? ○ mismatch of the species genetic pattern and the observed
○ vertical transmission of the symbiont from 1 generation to number of vent fields → there are probably more vent
the other fields in between the known vent fields
○ horizontal transmission; every animal has to take the ● additional pathways
symbiont up from the environment (e.g. tube worm) ○ 2023: discovery of underworld of hydrothermal vents
● How is a tubeworm taking up symbionts? (study of dispersal of tubeworms)
○ is a polychaete; infection happens via the skin ⥽ there is also dispersal via the subseafloor
○ bacteria infects worm → apoptosis of digestive tract → ○ in cave system: microbes, tubeworms, bristle worms,
formation trophosome (new organ) → animal without snails (all known from active vents); non-visible life still
digestive tract (is a sack filled with bacteria) needs to be analyzed
○ it develops hemoglobin which binds both oxygen (needed ○ existence of vent animal in caves: proof of life in the
for worm) and sulfide (toxic for worm) subsurface, proof that vent animals travel underneath the
● associated macrofauna (of the symbiosis) seafloor changes our understanding of dispersal at
○ deposit feeders; limpets, polychaetes deep-sea hydrothermal vents
○ suspension feeders (at low flow vents); barnacles, ○ proposed connectivity model between seafloor surface
anemones and crustal subseafloor hydrothermal vent
○ predators and scavengers; crabs, fish
○ associated macrofauna is highly abundant but species
poor → currently >1400 species described
3
SABINE GOLLNER –
○ for the majority of the seafloor, we don’t know what it
THE DEEP SEA looks like (satellites can’t penetrate into the ocean → no
video or photo material)
● our blue planet can be considered as our black planet, since
light does not penetrate deeply in our ocean
○ most abyssal seafloor is 3000-6000 m ABYSSAL PLAINS
○ deep sea is < 200 m (92% of the ocean)
○ 50% of the ocean is below 3000 m ● abyssal plains: areas on the seafloor (4000 m depth)
○ mean depth of the ocean is 3800 m ● abyssal plains are full with polymetallic nodules: mineral
● biomass is highest in the upper 200 m of the ocean, decreases secretions that live in specific parts
in the deeper sea, and shows a slight accumulation near the ● stable ecosystem
ocean floor ○ slow sedimentation rate:
○ T and light decrease with depth ⥽ a few mm per 1000 a (red clay)
⥽ 10-30 mm per 1000 a (oozes)
⥽ several m per 1000 a(close to rivers)
○ sedimentation rate is usually very slow → habitats are
very sensitive to disturbance; organisms aren’t adapted to
major disturbance events
○ future human disturbance by trawling of polymetallic
nodules (growth rate of nodules: 1-4 mm per 1 000 000 a)
● biological pump – deposition on the seafloor
○ food consumed by animals on the deep seafloor originates
from the upper 200 m of the water column
(phytoplankton → zooplankton → sinking particles)
○ 2-4% of the carbon uptake is stored in the seafloor
○ cold, slow sedimentation, little food
● deep sea characteristics
○ lack of light (light diminishes with depth)
○ high pressure (increasing with depth)
○ low temperature (2 °C)
○ stable temperatures
○ weak currents
○ low food availability
● deep sea is more than 1 ecosystem
○ abyssal plains
○ seamounts
○ continental margins (with canyons, cold seeps)
○ whale falls & wood falls
○ mid-ocean ridges (with hydrothermal vents)
DEEP SEA HAS A HIGH BIODIVERSITY
● examples of what the deep seafloor contains; mussel beds,
● Study (2000-2010) shows the number of known marine species
black smokers, shrimp swarms, limpets, abyssal plain (flat
was estimated to be 250.000. Now, it is estimated there are
area), sponges and anemones attached to nodules, nodule
million(s) species in the deep sea.
field, sea cucumbers, dumbo octopuses
○ knowledge is inversely correlated to size class
1
, LECTURE 10 – WEEK 5: deep-sea biology and deep-seabed mining marine sciences II
SABINE GOLLNER –
○ ~5% of the ocean has been systematically explored
○ number of specimens (N), number of species (S)
● deep-sea hydrothermal vents: energy rich, reduced and hot
fluids are venting out of the deep seafloor
○ found along mid-ocean ridges at places where the earth
plates are thin and diverging
● Even though that study is 15 years old, the big questions are ○ cold seawater (2 °C) sinks through cracks through the
similar; How many species are there, and how are they earth crust → water gets heated by the magma chamber
distributed? How big is the area that one species can inhabit, and loses chemicals, and get enriched in other chemicals
and what does that mean to our estimates of species richness (minerals; copper, zinc, iron, sulfur) → hot water (300-400
in the oceans of the world? °C) is pushed through channels where the earth crust is
● biodiversity – there is an unexpected high & hidden diversity finished and gets expelled into the ocean → hot water
of brittlestars (archetypal species) → when you look at gets in contact with the cold seawater → minerals
organisms, they might not be the same species precipitate → formation of black smokers (average size is
● biodiversity – Where do we find which species? 5-10 m)
○ there are more seafloor samples taken in the North Sea ○ mainly iron makes the smokers black
than the Pacific Ocean due to greater number of organism ○ steep gradient between hot water coming out of the black
records in well-studied areas → it’s difficult to draw smoker and cold surrounding seawater (2 °C)
conclusions about biodiversity
○ many deep-sea species are only discovered once
○ of a total of 275 polychaete morphotypes only 1
morphotype was shared among all 5 study areas
⥽ 49% morphotypes were only found in 1 area → show
high biodiversity in the deep sea
● biodiversity – How are populations connected?
○ if you want to study population connectivity, you need at
least 20 specimens of 1 species from 1 place → we don’t
know a lot of connectivity, because we don’t have the
amount of specimens to study it
● summary; food from surface waters, low food availability, low
faunal biomass; high biodiversity
HYDROTHERMAL VENTS (mid-ocean ridges)
● deep sea – energy input
○ deep sea live on abyssal plains are mostly dependent on
food production at the upper 200 m
○ (especially near mid-ocean ridges) there are ecosystems
that receive energy input by hot fluids venting out of the
seafloor by chemosynthesis ● global distribution of hydrothermal vent fields
○ abyssal plains are completely different from hydrothermal ○ mid-ocean ridges; all plates diverging locations
vent ecosystems with chemosynthesis ○ places with thin earth crust and a heat source below
2
, LECTURE 10 – WEEK 5: deep-sea biology and deep-seabed mining marine sciences II
SABINE GOLLNER –
● every vent field is unique at mid-atlantic ridge
○ different structures, biodiversity, community composition,
and dominant species due to biogeographic provinces
● ways of larval dispersal to another vent field by:
1) bottom currents (e.g. limpet larvae)
2) ridge-controlled currents (hydrothermal plume become at
a certain height neutrally buoyant → travel large
distances)
3) ocean currents (e.g. shrimp larvae)
● communities at hydrothermal vents
○ 1st level primary producers (not dependent on light) are
the basis of the food web
⥽ (chemo)autotrophic bacteria
⥽ autotrophic nutritional symbiosis
○ 2nd level primary consumers
⥽ deposit feeders
⥽ suspension feeders
○ 3nd level secondary consumers
⥽ predators
⥽ scavengers
○ organisms have to be adapted to the extreme conditions
of the hydrothermal vents
● unique endemic fauna at active hydrothermal vents is
dependent on chemosynthesis
○ megafaunal organisms (e.g. shrimp, mussel) live in
symbiosis with chemoautotrophic bacteria
● bacteria in symbiosis with macrofauna
○ episymbiotic; bacteria (symbiont) on gills of shrimp
⥽ bacteria on the Pompeii tube ● connectivity in a patchy environment
○ endosymbiosis; bacteria inside the mussel ○ distance needed to ensure connections of larvae
⥽ bacteria in tube worm (Riftia pachyptila); fastest (accounting for currents and larva life span): <150 km
growing animal on earth which is sessile ○ distance between active vent fields typically >150 km
● How is an animal taking up symbionts? ○ mismatch of the species genetic pattern and the observed
○ vertical transmission of the symbiont from 1 generation to number of vent fields → there are probably more vent
the other fields in between the known vent fields
○ horizontal transmission; every animal has to take the ● additional pathways
symbiont up from the environment (e.g. tube worm) ○ 2023: discovery of underworld of hydrothermal vents
● How is a tubeworm taking up symbionts? (study of dispersal of tubeworms)
○ is a polychaete; infection happens via the skin ⥽ there is also dispersal via the subseafloor
○ bacteria infects worm → apoptosis of digestive tract → ○ in cave system: microbes, tubeworms, bristle worms,
formation trophosome (new organ) → animal without snails (all known from active vents); non-visible life still
digestive tract (is a sack filled with bacteria) needs to be analyzed
○ it develops hemoglobin which binds both oxygen (needed ○ existence of vent animal in caves: proof of life in the
for worm) and sulfide (toxic for worm) subsurface, proof that vent animals travel underneath the
● associated macrofauna (of the symbiosis) seafloor changes our understanding of dispersal at
○ deposit feeders; limpets, polychaetes deep-sea hydrothermal vents
○ suspension feeders (at low flow vents); barnacles, ○ proposed connectivity model between seafloor surface
anemones and crustal subseafloor hydrothermal vent
○ predators and scavengers; crabs, fish
○ associated macrofauna is highly abundant but species
poor → currently >1400 species described
3
