SUBTIDAL: Sampling: Grabs & Box – corers Thorson ’s Peterson Sanders Rhoads & Young

DEEP-SEA: Planktonic supply of organic matter to the benthos decreases with depth and distance from the shore In estuaries, 30-50% of the annual 1º production reaches bottom sediments At m, only 2-7% Very refractory - VERTEX (Wakeham et al.)

Sinking rates vary from weeks to over a year per 1000 m As carbon input decreases to the deep sea, so does benthic metabolism Total oxygen consumption decreases greatly with depth from the shelf to the deep sea m ml O 2 h -1 vs m ml O 2 h -1 Microbial dynamics in deep sea poorly understood

Holgar Jannasch - “Alvin Lunch” - Accident discovery – 1540 m - loss of Alvin overboard; no one killed, recovered 10 months later, NO DECOMPOSITION of the lunches that were aboard Alvin. incubated deep-sea and shallow water bacteria on C-14-labeled substrates in experimental in-situ chambers at 5300 m and 1830 m <2% of what was in lab at 3 °C

(Jannasch, 1971) Suggests that increase in hydrostatic pressure raises the minimal bacteria growth temperature biomass changes with depth (limited by food supply) *see figure* (Dayton & Hessler, 1972): Low rates of predation might exert regulation effects Tunnicliffe, 1991)- High biomass: sloping portions of trenches - rapid downward transport - Aleutian Trench. Benthic-Pelagic Coupling – Smith (1998) – Benthic boundary layer (BBL)

Vents: Ballard (1977) - hot vent community Amer., French, Canadian, Soviet and Japanese collaboration on the discovery Vent Field - cluster of vents linked in subsurface Vent Site - general area - may include a few vent fields

The size of a vent can range in size from 2 m to a football stadium Typically found at the crests of Mid-Ocean Ridge History: Corliss et al., 1979 (Science) Jannasch et al., 1979 (Bioscience) Karl et al., 1980 (Science) Cavanaugh et al., 1981 (Science) Lutz et al., (Science) Grassle, 1985 (Science) Smith et al., 1989 (Nature) Van Dover, 1990 (Nature)

Richard Lutz - - most vent species probably have lecithotrophic larvae - low temperatures can slow development and increase larval life Comparison of pure hydrothermal fluids with ambient deep-sea water that are of biological significance include: up to 400°C, pH = 3.2, high sulfide 350 uM, salinity typically 2 x, oxygen, nitrite, phosphorus not present. Mg - not in vent water, but used to test for purity

In the presence of dissolved sulfide ions - formation of polymetallic sulfide deposits - chemosynthetic microbes (organic carbon) Best known vent sites are those on the Galapagos Rift, East Pacific Rise Scales of variability influence biological processes (see diagrams)

Vent Organisms: Phylum Pogonophora – Vestiminifera Lack mouth and gut, Riftia pacyptila and Ridgeia spp. – kg/m 2 - can grow 1.5 m in 1.5 years Harbor symbiotic chemoautotrophic sulfide-oxidizing bacteria in vascularized tissue (trophosome). Manufacture ATP with energy from sulfide oxidation and reduce CO 2 to organic matter. Have specialized hemoglobin which binds oxygen to sulfide for transport to the trophosome.

Limpets, mussels (Mytilidae) Bathymodiolus brevior, clams Calyptogena magnifica, crabs Bythograea therydron Refugia?? - Taxonomic novelty may be survivors of Mesozoic and Cenozoic extinctions