Deep-Sea Communities

OCN 201 Biology Lecture 11 The Deep Sea By Volume 4.9% 18.6% 45.4%

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0.7% Deep-Sea Habitats • The deep sea is the largest living space on our planet MANY DISTINCT HABITATS • Submarine canyons • Cold seeps • Manganese nodule fields • Brine pools • Abyssal plains • Whale falls • Oxygen minimum zones • Deep pelagic • Deep-sea trenches • Seamounts • Mid-ocean ridges • Wood falls • Hydrothermal vents • Cold-water coral gardens The Deep-Sea Environment

•Physical Conditions • Cold (typically 1 - 4⁰C) • High Pressure • Dark

•Limited food availability Depth (m) (m) Depth • Marine snow: Falling detritus from the surface • Fecal pellets Occasional carrion: large carcasses • Temperature (⁰C) The Deep-Sea Environment

•Physical Conditions • Cold (typically 1 - 4⁰C) • High Pressure • Dark

•Limited food availability Marine snow • Marine snow: Falling detritus from the surface • Fecal pellets • Occasional carrion: large carcasses The Deep-Sea Environment

•Physical Conditions • Cold (typically 1 - 4⁰C) • High Pressure • Dark

•Limited food availability Marine snow • Marine snow: Falling detritus from the surface • Fecal pellets • Occasional carrion: large carcasses Benthic Deep-Sea Habitats NOAA OER MBARI Abyssal Plains=MBARI

• Comparatively Low Numbers (not much food)

• High Diversity (resource limited)

• Long Lives (lower metabolic rates)

MBARI MBARI NOAA OER MBARI Abyssal Plains

• Many deposit feeders and scavengers

• Epifauna - urchins, brittle stars, etc

• Infauna - crustaceans, worms, etc.

University of , Alan Jamieson NOAA OER Cold-Water Corals

2000 m, Johnston Atoll NOAA OER

• Filter-feeders – no photosynthetic symbionts

• Long-lived, slow-growing

• Found in areas of high current flow – seamounts, local high features Cold-Water Corals

• Create an important habitat for associate fauna

• Seastars, brittle stars, crabs, amphipods, acorn worms, barnacles, isopods, snails, crinoids …

2000 m, Johnston Atoll NOAA OER Cold-Water Corals

• Create an important habitat for associate fauna

• Seastars, brittle stars, crabs, amphipods, acorn worms, barnacles, isopods, snails, crinoids …

Predators feeding on the coral itself acorn worm

2000 m, Johnston Atoll NOAA OER Hydrothermal Vents and Cold Seeps

Primary Production by Chemosynthesis! Hydrothermal Vents

H S 2

at rift zones; seafloor spreading centers Photo- vs Chemosynthesis

Light Energy

6CO + 6H O C H O + 6O 2 2 6 12 6 2

O + ChemicalH S Energy H O + S 2 2 2

6CO + 6H O C H O + 6O 2 2 6 12 6 2 Chemosynthesis

• Production of organic matter through reactions of inorganic chemicals • Usually in the absence of sunlight • A second source of Primary Production in the sea • Only bacteria can do it • But animals have endosymbiotic bacteria that provide them with nutrition Hydrothermal Vents

• Extremely rich, high biomass communities, discovered in 1976 • Short-lived habitats • Home to many specialized organisms Ex: tubeworms with chemosynthetic symbionts, yeti crab that grows bacterial mats Cold Seeps Cold water seeping from sediments carrying: - hydrogen sulfide (H S) 2 - methane (CH ) 4 Whale Falls

Stage 1 – mobile scavengers hagfish sleeper sharks amphipods Whale Falls

Stage 1 – mobile scavengers Osedax hagfish sleeper sharks amphipods Stage 2 – enrichment opportunists polychaete worms molluscs crustaceans Whale Falls & Wood Falls Stage 1 – mobile scavengers hagfish sleeper sharks amphipods Nautilus Live

Stage 2 – enrichment opportunists Michael Rothman polychaete worms molluscs crustaceans Stage 3 – sulfophilic stage bacterial mats archaea The

• Subduction zones

• Deep-sea trenches are deep!

• May act as a funnel for organic matter

Shank et al., WHOI

• Areas of endemism containing species that are only found in one location

Jamieson et al., Deep-Sea Microbial

Communities SIO • Piezophiles – “pressure-loving” microbes

• Adaptations to high pressure • Membrane fluidity • Membrane proteins • DNA replication • Motility adaptations Kato et al. 1998 • Active area of research

summarized from Bartlett & Peoples Lecture ZoBell, Galathea Human Impacts on the Deep Sea

Pham et al., 2014

• The deep sea may seem remote, but it is closely connected to the rest of the ocean Human Impacts on the Deep Sea

• Polymetallic nodules • Understudied habitats • Proposed mining in large areas of the seafloor • Contain economically important minerals • Could have a large impact on the area

Ifremer, Nodinaut cruise, 2004

• The deep sea may seem remote, but it is closely connected to the rest of the ocean We are still in an era of deep-sea exploration!

Ethereal , Deepest-living fish A way to view deep-sea exploration live from home: SOI http://oceanexplorer.noaa.gov/okeanos/welcome.html Deep Pelagic How much food is there?

(Martin et al. 1987)

83% of the biomass in the sea is in the EPIPELAGIC But not everything waits for food to fall down! Deep Scattering Layer Vertical migration by plankton and their predators

Sonar

Largest migration on the planet ! Deep Scattering Layer Migrating to mesopelagic at dawn

Sonar

daytime depth

http://www.pifsc.noaa.gov/cruise/oes0902.php Adaptations in the Deep Pelagic

• Clear bodies or reflective sides and counterillumination (disphotic zone) • Red or Black bodies (aphotic zone) • Specialized eyes (or degenerated) • • Stealth feeding & large prey: Oversize mouths, increased gape, lures Transparent body large eyes Reduced Silhouette Reflective Sides Counterillumination Counterillumination

http://lifesci.ucsb.edu/$biolum/organism/movie.html Bioluminescence Light produced by a biochemical reaction

• Counterillumination (camouflage) • Communication (finding mates) • Lures (enticing prey) • Searchlights (illuminate prey) • Decoy or surprise (escape from predator).

~ 70% of fish, 80% crustaceans below 500 m are bioluminescent

Red & black bodies

Oversize mouths Parasitic males Adaptations to mate finding in a dilute ocean

male fuses with female organs degenerate Bioluminescence Questions?