Deep-Sea Communities

OCN 201 Biology Lecture 11 In which part of the ocean is most of the biomass?

A: epipelagic B: mesopelagic C: bathypelagic D: abyssopelagic E: hadopelagic Primary The Deep Sea Production By Volume 4.9% 18.6% 45.4%

30.3%

Previously believed 0.7% that the deep sea had no life 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) Depth (m) (m) Depth • High Pressure • Dark

Temperature (⁰C) The Deep-Sea Environment

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

• Food Limited Marine snow • Marine snow: Falling detritus from <1% at the surface 4000m • 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 >50% of the seafloor

• 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 Hawaii, Leitner and Drazen NOAA OER Which of these is NOT true about abyssal plains?

A: low numbers of animals B: cold C: small portion of the ocean floor D: food limited E: scavenger and deposit feeders common Seamounts An undersea mountain usually of volcanic origin that rises more than 1000 m (3280 ft) Highest point in the Koolau Mountain range is about 960 m or 3150ft. So some people include smaller features as well (down to about 100m or 330 ft) Seamounts There are LOTS of them!!!!! Most are in the Deep Sea! (mesopelagic and below)

Kim and Wessel 2011 Diverse Habitats = Diverse Biology The Seamount Effect

• High Abundance • High Biomass • High Biodiversity Image courtesy of NOAA office of Ocean Exploration and Research High Biomass & Abundance

• Pelagic • Aggregations • Visitors • Residents

• Benthic • Bottomfish aggregations • Sponge Gardens • Coral Gardens

Image courtesy of NOAA office of Ocean Exploration and Research 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 What do we call primary production that uses chemical energy to fix carbon?

A: chemosynthesis B: chemoheterotrophy C: photosynthesis D: photoheterotrophy E: heterotrophy Hydrothermal Vents and Cold Seeps

Primary Production by Chemosynthesis! Hydrothermal Vents

H S 2

at rift zones; seafloor spreading centers •PhotoProduction- vsof organic Chemosynthesis matter through reactions of inorganic chemicals

• Usually inLight the Energyabsence of sunlight • Only source of Primary Production in the deep 6CO + 6H O C H O + 6O • Only2 bacteria2 can do it 6 12 6 2 • But animals have endosymbiotic bacteria that provide them with nutrition

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

6CO + 6H O C H O + 6O 2 2 6 12 6 2 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 Osedax Stage 1 – mobile scavengers 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 – sulphophilic stage bacterial mats archaea How many dollar bills would it take to get to the bottom of the Mariana Trench?

A: $450 Challenger Deep B: $1,000 10,984 ± 25 m C: $2,500 D: $5,000 $69,892 E: $70,000 The Hadal Zone

• 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

• Some of the least explored habitats on our planet

Jamieson et al., University of Aberdeen 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

• Contain economically important minerals

• Proposed mining in large areas of the seafloor

• Could have a large impact Ifremer, Nodinaut cruise, 2004 on the area

• 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 snailfish, Mariana Trench Deepest-living fish, to ~8,200 m A way to view deep-sea exploration live from home: SOI http://oceanexplorer.noaa.gov/okeanos/welcome.html Questions?