Deep-Sea Communities OCN 201 Biology Lecture 11 The Deep Sea By Volume 4.9% 18.6% 45.4% 30.3% 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) Depth (m) • 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 Aberdeen, 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 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 Jamieson et al., University of Aberdeen 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 snailfish, Mariana Trench 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) • Bioluminescence • 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?.