Hydrothermal vents are hot springs located on the seafloor near volcanically active areas. They form when seawater is heated by magma under the ocean crust, emerging as hot fluids containing dissolved metals. Unique ecosystems have evolved around hydrothermal vents, supported by chemosynthetic bacteria that form the base of the food web. Characteristic animals include tube worms, shrimp, crabs, and octopuses. While biodiverse, hydrothermal vent ecosystems are threatened by recent interest in seabed mining for metals deposited by the vents.

1. 1

2. HYDROTHERMAL VENTS
http://five-oceans.co/the-issue-with-seabed-mining/
2

3.  Hot springs produced by underwater volcanoes at spreading ridges or convergent plate
boundaries.
 FUNCTIONING
• Water percolates through cracks in the sea floor and is heated by magma deep below the
ocean crust(subduction zones) to 700ºF. This hot fluid (hydrothermal fluid) rises to the
surface carrying dissolved metals and other chemicals that harden around the rim of the
vent.
 TRIVIA
• Hot seawater in hydrothermal vents does not boil.
• These were discovered in 1977 in a scientific submersible called Alvin in the Pacific
Ocean near the Galapagos Islands.
• Death of a vent.
3

4. Reference:
http://faculty.montgomerycollege.edu/gyouth/FP_examples/student_examples/sathya_ram
achandran/phenomenon.html 4

5. 5
The Mineral Cycle

6. DISTRIBUTION
• The diagram below shows us the MID OCEAN RIDGE SYSTEM
• Some vents may also be found at intra plate locations like volcano hotspots, hitherto there are 500
known active submarine hydrothermal vent fields around the world.
6

7. https://en.wikipedia.org/wiki/Hydrothermal_vent

8. COMMON RIDGES
8
[http://www.nature.com/nature/journal/v439/n7079/images/hydro_vents/southern.html

9. TYPES
9

10. 10
1. BLACK SMOKERS
• Emit clouds of black material, which are sulphur bearing minerals or sulphides.
• The chimney is formed due to deposition of iron sulphide which solidifies on
coming in contact with near freezing water of the deep sea. The deposited
sulphides can give rise to massive sulphide ore deposits over time.
• The world’s deepest known black smoker is located 3000m below earth’s surface
called Cayman’s trough.
2. WHITE SMOKERS
• Emit lighter hued chemicals such as calcium, barium and silicon sulphides.
• These are formed due to the crystallization of magma(waning hydrothermal fields)
which makes sea water dominate the magmatic water.
• Gives rise to carbonate and sulphate rich(barite and anhydrite) deposits with
lower vent temperature.

11. BIOLOGICAL COMMUNITIES
11
https://en.wikipedia.org/wiki/Giant_tube_worm
Riftia pachyptila

12. Tube Worms
• Have red plumes which serve as sites for bacteria to thrive in- symbiotically
12
•Marine invertebrates of the phylum Annelida.
•Are confined to pelagic and intertidal zones,
Near the black smokers.
•Bacteria makes half of their body weight.
•Bright red colour of the plume is due to the
Presence of haemoglobin which helps them
Carry oxygen in the presence of suphide.
•Are the primary feeders in the vent system.

13. 13
Microbial Mats of
Epsilonproteobacteria
http://oceanexplorer.noaa.gov/explorations/12fire/background/microbio/microbio.html

14. Chemoautotrophic
bacteria
Tube worms
(Riftia pachyptila)
Vent shrimp
(Rimcaris sp.)
Blind crabs
14

15. 15
Top level predator
the vent octopus aka
Vulcunoctopus hydrothermalis
Shrimps feeding on
Vent mussels

16. 16
THE DOUBT AS PER GAURAV AND ANUSHKAS WISH
The vent shrimp Rimicaris exoculata (literally the Rift-shrimp
deprived of eyes) swarms hydrothermal chimneys, with temperatures
reaching over 350 C, en masse in the darkness of the deep sea. It has
a certain peculiarity in that its eyes are completely absent yet there is
a high concentration of the visual pigment,rhodopsin, in a dorsal
“eyespot” beneath a transparent cuticle of the carapace (see shiny pink
parts on image
http://www.journals.uchicago.edu/doi/10.230
7/1542679
http://www.deepseanews.com/2010/04/the-
eye-of-the-vent-shrimp/

17. EXPLOITATION
• Hydrothermal vents, in some instances, have led to the formation of exploitable mineral
resources via deposition of seafloor massive sulfide deposits. The Mount Isa ore body
located in Queensland, Australia, is an excellent example. Many hydrothermal vents are
rich in cobalt, gold, copper, and rare earth metals essential for electronic components.
• Companies such as Nautilus minerals have succeeded in returning over 10 metric tons of
mined SMS (seafloor massive sulphide) deposits using drum cutters.
• The historical mammoth copper mines of Cyprus were also formed due to hydrothermal
activity before the sea bed was uplifted .
• These mining activities lead to various environmental impacts such as dust plumes from
the mining machinery which affects filter feeding organisms, collapsing or reopening of
vents, methane clatherate release or even sub oceanic landslides which have dire
consequences on the natural flora and fauna present around the vents.
17

18. 18

19. • Coral reefs are diverse underwater ecosystems held
together by limestone structures secreted by coral, the
organism primarily associated with coral reefs.
• Coral : transparent/translucent marine invertebrates, class
anthozoa, phylum Cnidaria, exist in the form of colonies of
many individual polyps that produce sexually and asexually.
• Can survive independently(nematocysts) but usually are in
symbiotic relationship with photosynthetic dinoflagellates
called zooxanthellae.
• Reefs get their colour via billions of zooxanthellae (algae) .
19

20. OPTIMUM CONDITIONS FOR PROLIFERATION
• Occur only in shallow regions where sunlight can easily reach due to symbiotic
relationship with algae.
• Grow in both temperate and tropical waters but usually more in tropical, with optimum
temperature of 26-27ºC, and are extremely sensitive to change in temperature.
• The currents must be mild enough to allow anchorage along with no upwelling i.e.
motion of cool, nutrient rich water to the warmer ocean surface by the wind.
• The water has to ‘clear’ i.e. free of drifting plankton and nutrients, as told by Darwin’s
paradox.
• Sometimes depend on surrounding habitats like mangroves and sea grass forests.
20

21. FORMATION
21

22. TYPES
22

23. ZONES
23

24. 24

25. MAIN THREATS TO
CORAL REEFS
i. Overfishing
ii. Careless tourism
iii. Pollution
iv. Sedimentation
v. Coral mining
vi. Climate
vii. Ozone depletion
25

26. FLORA AND FAUNA
• Common flora found include different types of algae and phytoplankton. Algae is known
for encroaching reefs and hence have to be controlled. Examples of algae seen are
Turf algae, Coralline algae and macro algae.
• Sponges like tube sponges are necessary detrivores.
• Fish : 400 species inhabit the coral reefs including parrotfish, cardinal fish and surgeon
fish.
• Invertebrates – sea urchins like Diadema, sea slugs, mollusks, polychaete worms,
crustaceans etc.
• Seabirds – different species of Albatross ,brown boobies and pelicans( total of 1.5
million species).
• There are also others like sea snakes eels and turtles.
26

27. 27

28. 28

29. FACTS
• CORAL REEFS COVER LESS THAN 0.2% OF THE TOTAL OCEAN AREA BUT
COTAIN 25% OF THE WORLD’S MARINE SPECIES.
• THEY SECOND RAINFORESTS IN TERMS OF BIODIVERSITY OF SPECIES.
• FRINGING REEFS TAKE THOUSANDS OF YEARS TO FORM AND AN ATOLL
CAN TAKE UPTO 30 MILLION YEARS TO FORM.
• THE GLOBAL ECONOMIC VALUE OF CORAL REEFS IS ESTIMATED TO BE
BETWEEN US $29.8 BILLION TO $375 BILLION PER YEAR.
29

30. CONSERVATION
• MARINE PROTECTED AREAS.
• GREAT BARRIER REEF MARINE PARK AUTHORITY
• BIOSPHERE RESERVES AND WORLD HERITAGE SITES
• RESTORATION
30

31. REFERENCES for coral
• http://www.livescience.com/40276-coral-reefs.html ..for threats on coral reef
• http://wwf.panda.org/about_our_earth/blue_planet/coasts/coral_reefs/coral
_importance/
• http://www.reef.edu.au/rh.html
• https://ocean.si.edu/corals-and-coral-reefs
• http://www.defenders.org/coral-reef/basic-facts
• https://en.wikipedia.org/wiki/Coral_reef
• http://www.nature.com/news/2009/090323/full/news.2009.185.html-
………..>For age and lifespan…mostly depends on species involved.eg. In brain
coral and black coral.
31

32. FIN 32