1. Deep Sea: Introduction
The deep sea is least understood ocean habitat
Less productive and more sparsely inhabited than ecosystems in the photic zone

2. The Deep Sea: Introduction (cont.)
Bathypelagic Zone
perpetual darkness
75% of the ocean; the largest habitat on the planet
constant temperature and salinity
organisms dominated by white, red, or black coloration
some bioluminescence

3. Variations of Deep Sea Benthos
By substrate type
By depth
By food concentration

4. Deep Sea: Primary Production
No photosynthesis below 150 m
Typical organic composition of the sea bed
Continental shelf: 2-5%
Abyss: <0.5%

5. Substrate Type
Rocky habitats are rare

6. Substrate Type Soft sediments Epifauna (on top of sediment)
Infauna (within sediment)

7. Sampling the Benthos
Grabs
Cores
Dredges
Trawls
Cameras

8. Smith-Macintyre Grab

9. Multi-corer

10. Cameras

11. Classification Sieve size Megafauna Rare, Largest animals Macrofauna
> 1mm (usually retained on 0.5 mm)
Meiofauna
0.1 – 1 mm (passing 0.5 mm, retained on mm
Microfauna
<0.1 mm
Sieve size

12. Faunal Composition

13. Meiofauna Harpacticoid copepods Nematodes Small annelids
Larger protozoa (ciliates, foraminifera)

14. Dominant groups of the deep sea floor macrofauna
echinoderms- especially sea cukes and crinoids
polychaetes
pycnogonids
isopods/amphipods

15. Abyssal Polychaets Small size Reduced number of segments
Reduced parapodia
Reduced coloration
Reduced eyes

16. Crustacea
Amphipods
Isopods
Tanaids

17. Molluscs
Bivalves
Gastropods
Scaphopods (tooth shells)

18. Swimming sea cucumbers
Enypniastes eximia can be up to a foot in length.
Enypniastes is one of a small group of swimming sea cucumbers. It also feeds on bottom sediment, which it stuffs into its mouth with the tube feet surrounding the mouth.

19. Cephalopods Some with weak swimming abilities (plankton)
Other larger nektonic species
Most are bioluminescent

20. Crustaceans Shrimp, copepods, ostracods and euphausids
Most are bioluminescent
Tend to be purple or bright red in coloration
Bioluminsecence flashes blue

21. Fishes Most are small (2-10 cm) Large mouths (many are hinged)
Broad diets (anything they can fit in their mouths)
Sharp incurved teeth
Coloration
Tend to be silver-grey or black

22. General characteristics of deep sea fishes
low metabolic rate
less muscle mass: gelatinous
adapted for large rare meals: large mouths and stomachs
use of lighting/
bioluminescence: most common in upper areas of deep (meso- and upper bathypelagic)

23. Biodiversity

24. Biodiversity of the Deep Sea
Each major ocean basin has distinctive fauna
Benthic deep sea is surprisingly diverse (100s of species per m2 on ocean floor)
Small-scale patchiness created by ephemeral food patches, etc .
Larger-scale upwelling disturbance, bottom boundary currents, slumping from continental shelves all create a diverse habitat

25. Inverse Relationship Between Biomass and Diversity
Shallow
Deep
Reduced competition
Increased specialization
Biomass
Diversity

26. High Deep-Sea Diversity
Rockall
Lock Etive

27. High Diversity in Deep-Sea Sediments
Competitive co-existence based on niche partitioning and specialization
Small-scale disturbances creates habitat heterogeneity
Large-scale effects from currents enhance recruitment/dispersal and re-shape landscape

28. Niche Differentiation
Habitat creation and modification

29. Small-Scale Disturbances
Food falls

30. Large-Scale Disturbances
Currents and deep sea benthic storms
Diversity
Velocity
Increasing recruitment
Reshaping
landscape
Resuspension and burial

31. Endemism
High in abyssal plains
Highest among trench fauna

32. Deep Sea: Food Sources
rain of organic matter from above is sole source of food
exceptions - seep and vent communities
chemosynthetic bacteria (chemoautotrophs)

33. What from above is eaten and how?
30-40% of organic matter is first absorbed by benthic bacteria, which are consumed by larger deposit feeders.
Vast majority consumed by deposit feeders
Small proportion by suspension feeders (~7%): attached to very limited hard substrates: little water movement and little suspended food

34. Whale carcass communities
Whale carcasses provide a pulse of nutrients to deep-sea benthic communities, which form around them
significant source of sulfides, methane for primary chemosynthetic producers
serve as “stepping-stones” for many benthic species also found at hydrothermal vents and seeps

36. Whale fall
This polychaete worm, discovered at a whale fall in the Santa Cruz. CA basin, is new to science and may be a whale fall specialist.

38. The Deep Sea: Hydrothermal Vents
A hydrothermal vent is a geyser on the seafloor.
It continuously spews super-hot, mineral-rich water that helps support a diverse community of organisms.
Although most of the deep sea is sparsely populated, vent sites teem with a fascinating array of life.
Tubeworms and huge clams are the most distinctive inhabitants of Pacific Ocean vent sites, while eyeless shrimp are found only at vents in the Atlantic Ocean

39. The Deep Sea: Hydrothermal Vents
The first hydrothermal vent was discovered in 1977, and hydrothermal vents occur in the Pacific and Atlantic oceans.
Most are found at an average depth of about 2,100 meters (7,000 ft) in areas of seafloor spreading along the Mid-Ocean Ridge system— the underwater mountain chain that extends throughout the world’s oceans.

40. The Deep-Sea: Where are Hydrothermal Vents Found?
The Mid-Ocean Ridge is the most volcanically active continuous zone on Earth.
Vents are normally found along the crests of the Mid-Ocean Ridge
One famous vent site is on the East Pacific Rise, an underwater mountain range close to the Galapagos Islands.

41. Vents and Tectonic Activity

42. The Deep Sea: The Origin of Hydrothermal Vents
How do hydrothermal vents form?
In some areas along the Mid-Ocean Ridge, the plates that form the Earth’s crust are moving apart, creating cracks and crevices in the ocean floor.
Seawater seeps into these openings and is heated by the molten rock, or magma, that lies beneath the Earth’s crust. As the water is heated, it rises and returns into the ocean through an opening in the seafloor

43. Marine Ecology:The Deep-Sea
Hydrothermal vents form when hot, mineral rich water flows into the ocean floor through volcanic lava on a mid-ocean ridge volcano formed by sea-floor spreading.
Sulfide minerals crystallize from hot water directly onto the volcanic rocks at the same place where hot mineral rich water flows from the ocean floor.

44. The Deep Sea: Hydrothermal Vent Structure
Chimneys top some hydrothermal vents.
These smokestacks are formed from dissolved metals that precipitate out (form into particles) when the super-hot vent water meets the surrounding deep ocean water, which is only a few degrees above freezing.
Black smokers are the hottest of the vents. They spew mostly iron and sulfide, which combine to form iron monosulfide. This compound gives the smoker its black color.
White smokers release water that is cooler than their cousins’ and often contains compounds of barium, calcium, and silicon, which are white

45. The Deep Sea: Hydrothermal Vents Impact Ocean Chemistry
Seafloor hydrothermal systems have a major local impact on ocean chemistry of the ocean.
Some hydrothermal tracers (especially helium) are found thousands of kilometers from hydrothermal sources, are used to study deep ocean circulation. Because hydrothermal circulation removes some compounds (e.g. Mg, SO4) and adds others (He, Mn, Fe, H2, CO2), it plays an important role in governing seawater mineral composition

46. Hydrothermal Vents Physical and chemical characteristics of vents
Single chimneys arranged in a field (a ‘vent field’)
Fields are m across
Black smokers ( C)
Rich in sulfides
Toxic metals
Low oxygen
White smokers (5-100 C)
Short-lived (10-20 yrs in Pacific)
Explosive endings

47. Black Smokers

48. White Smokers

49. Hydrothermal Vents are Oases in the Deep Sea
Rich and abundant biological communities,
in contrast to most all of the deep sea
Over 300 spp. described globally
Some are cosmopolitan species
-vestimentiferan worm Riftia pachyptila
-mussel Bathymodiolus thermophilus
-clams Calyptogena magnifica

50. Deep-Sea Vent Communities
Around these vent sites live communities of highly specialized animals
Tube worms, mostly vestimeniferans (Riftia pachptila) & other organisms live in darkness, extreme pressure, and vent water temperatures from 10°C to 400°C
All these creatures are dependant on bacteria which use H2S from vent water as a primary energy source. These bacteria occur in the tissues of clams and tube worms and utilize the H2S which would otherwise be toxic to other organisms

51. Primary Production at Hydrothermal Vents
Chemolithoautotrophy= chemosynthesis
CO2 + H2S +O2 +H2O
CH2O + H2SO4
Bacteria do the fixing of carbon from CO2
Symbiotic with other metazoans or free-living in mats
CH4 (methane) may substitute in cold seeps

52. Vestimentiferan worms
Vestimeniferan worms (Riftia pachptila) found abundantly near deep-sea hydrothermal vents

53. The Deep-Sea: Special Adaptations for life
In Vestimentiferan worms the Plume is a soft, bright-red structure that functions as a mouth. It takes in oxygen, carbon dioxide, and hydrogen sulfide that microbes living in the worm's body use for growth
In hot water from the vent, these compounds can react violently. Yet, using special hemoglobins in its blood-rich plume (hence the red color), the tubeworm can transport the ingredients in its blood without this reaction taking place -- and without the toxic H2S poisoning it

54. The Deep-Sea: Mutualisms play a role in the persistence of life
Trophosome is a dark green-brown tissue where microbes (~ 285 billion bacteria per ounce of tissue.) live symbiotically within the worm
The microbes get a safe place to live and give the worm its food.
by absorbing CO2,O2 and H2S from the plume and controlling their reaction, the microbes use the chemical energy released from oxidizing sulfide to fix CO2 into organic carbon that nourishes both the microbes and the worm.

55. Secondary Production at Hydrothermal Vents
Bathymodiolus thermophilus

56. Secondary Production at Hydrothermal Vents
Calyptogena magnifica

57. The Deep Sea: Hydrothermal Vent Communities
Pogonophorans
tube worms
no mouth, no stomach
Sea Fans
Crabs
Shrimp
Snails
Clams

58. Mussel bed communities

59. Secondary Production at Hydrothermal Vents
Bresiliid shrimps

60. Bresiliid dorsal organs

61. Hydrothermal Vents Contained...
1 new class, > 14 new families, 50 new genera
These include mollusks, polychaetes, arthropods, with
93% of species described from vents and 90% restricted
to vent habitats. Thus, there is high endemicity at vents

62. Colonization of Hydrothermal Vents
The ephemerality of vents (often lasting only a few
years) requires...
Rapid growth and early maturity
Overcoming special larval dispersal and recruitment problems
Calyptogena (mussel) reaches maximum size (~240 mm) in 20 years, but may live as long as 100 yrs.
Possible ‘stepping stones’ between fields?

63. Cold Seeps
Cold seeps are shallow areas on the ocean floor where gases percolate through underlying rock and sediment layers and emerge on the ocean bottom.
The gases found in the seep are methane and sulfur-rich gases and sediments releasing petroleum.
Active seeps are located in subduction zones, which are areas where continental plates are being pushed together, with one diving beneath another

64. Cold Seep Communities
One common type of organism that lives in the cold seep is a tubeworm.
These are related to the tubeworms that live in the hydrothermal vents.
These organisms are the longest living invertebrates we know of.
They are estimated to have a life span of years old.
While they are similar in length to their hydrothermal cousins (~ one-two meters long), they are slow-growing with a rate of one inch or less per year.

65. Cold seep community
Gulf of Mexico

66. Similarities with vents: similar taxa

67. White Regions Mark Areas of New Growth < 3 cm in a year = more than 100 yrs old.

68. Methane seeps
One of the most exciting organisms found in a cold seep is a worm.
The polychaete worm, known as an iceworm was found living on methane ice.
The iceworms, a new species of polychaete are the only known animals to colonize on methane hydrates.
Many marine worms have a close relationship with bacteria.
Iceworms do not seem to play host to bacteria, traces of bacteria in the gust suggest that the worm do eat them.

69. Brine pool 13 m across is 4x saltier than seawater and rich in methane

70. Ice worms (polychaetes) living on gas hydrates in Gulf of Mexico

71. The Deep Sea: The persistence of vent life
The irony of vent communities is that, despite their harsh environment, they appear to have survived for many millions of years, and have apparently changed little in that time. Vent life appears to be more closely related to ancient animals than anything alive today.

72. The Deep-Sea: Did life begin at Hydrothermal Vents?
While periodic mass extinctions have swept the Earth, vent creatures seem to have been unaffected, leading some to suggest that a vent-like environment was the place where life on Earth likely got its start.
If this could have occurred here on Earth, why not on other planets that have the necessary ingredients, including heat, water, and the right mix of chemicals? In the end, there may indeed be a harsher place to live than hydrothermal vents. But it hasn't been found ... yet.

73. Extremeophiles

74. Hydrothermal Vents on Mars Could Have Supported Life By Andrea Thompson Senior Writer posted: 22 May :00 pm ET

76. Hydrothermal Vents History of discovery
1979 ‘Rose Garden’ in the Galapagos Rift region

78. Black Smokers

79. Colonization of Hydrothermal Vents
Ephemerality of hydorthermal vents requires...
Rapid growth and early maturity
Overcoming special larval dispersal and recruitment problems
Calyptogena reaches maximum size (~240 mm) in 20 years, but may live as long as 100 yrs.
Possible ‘stepping stones’ between fields?

82. Secondary Production at Hydrothermal Vents
Riftia pachyptila

83. The Deep-Sea: What benefits can come from the study of Hydrothermal Vents
The bacteria that thrive in this environment produce enzymes that are essential to industry. Examples of possible uses include: dislodging of oil inside wells; the development heat stable enzymes and culturing bacteria designed to decompose toxic waste.
Vent chimneys are rich in metals such as copper, zinc, iron, and gold.
The discovery of life in these extreme environments have elicited discussions about life on other planets such as Jupiter’s moon Europa.
Deposition of one million tons of sulfide ore is something to think about in the future when our more accessible mineral deposits on land are being depleted rapidly.

84. Deep-Sea Vent Communities
Around these vent sites live communities of highly specialized animals
Tube worms, mostly vestimeniferan worms (Riftia pachptila) & crustaceans live in darkness, extreme pressure, and vent water temperatures from 10°C to 400°C
All these creatures are dependant on bacteria which use hydrogen sulphide from vent water as a primary energy source

85. The Deep-Sea: Challenges of Living in the Deep-Sea
Bacteria utilize chemosynthesis and are primary producers that use carbon dioxide as a carbon source and gain energy through the oxidation of inorganic substances like hydrogen sulfide. This adaptation enables sulfur to be more readily utilized in chemosynthesis.
The shrimp species that dominate hydrothermal vents in the Mid-Atlantic do not have eyes. Instead, some species have a sensor on their heads that is sensitive to high temperatures thereby enabling the organism to detect heat.

86. The Deep-Sea: Challenges of Living in the Deep-Sea
Extremely high pressures affect the stability of enzymes necessary for survival.
Low concentration of oxygen due to extremely high temperatures of surrounding water. Organisms must be strictly anaerobic.
Extremely high temperatures may denature proteins/enzymes, destabilize organisms' transfer RNA, biological cofactors and organic intermediates.
The difficulty in maintaining membrane fluidity at high temperatures.

87. Bioturbation
oxygenated
oxygenated
Varve formation in sediments

88. Depth Gradients
1 order magnitude / 1000 m

89. Diversity Measures
Rarefaction
curves
Species-area
curves

90. Endemism
Occurrence of organisms or taxa (termed endemic) whose distributions are restricted to a geographical region or locality
high in abyssal plains
highest among trench fauna

91. Chemosynthetic Food Webs
Sulfur bacteria in the tissues of clams and tube worms utilize the sulfates which would otherwise be toxic to other organisms
This forms the basis of a non-photosynthetic food webs found throughout the oceans