Loading in 2 Seconds...
Loading in 2 Seconds...
BIOLOGY 457/657 PHYSIOLOGY OF MARINE & ESTUARINE ANIMALS. March 8, 2004 Physiological Adaptation to the Deep Sea. FEATURES OF THE DEEP SEA. Area: The deep benthos and its overlying waters occupy a large area and a huge volume . FEATURES OF THE DEEP SEA.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
BIOLOGY 457/657PHYSIOLOGY OF MARINE & ESTUARINE ANIMALS March 8, 2004 Physiological Adaptation to the Deep Sea
FEATURES OF THE DEEP SEA Area: The deep benthos and its overlying waters occupy a large area and a huge volume
FEATURES OF THE DEEP SEA Light: essentially absent, except for bioluminescence Temperature: low (~4°C) and constant Salinity: constant (~35°%) Oxygen: generally adequate (may be depleted near substratum) Pressure: greatly elevated (can exceed 1000 atm) Food supply: extremely limited (except near hydrothermal vents)
ANIMALS OF THE DEEP SEA Diversity is great: invertebrates may be very unusual Density is very low (except at hydrothermal vents) Energy content of animals is unusually low Metabolic rates also tend to be very low Sizes of animals can be unexpectedly large
BIOLOGICAL ADAPTATIONTO THE DEEP SEA Light: enlarged eyes, photophores, black or red coloration, transparency Temperature: maintain low metabolic rates Salinity: no adaptation required, since it is constant & reliable Oxygen: no special adaptations normally required Pressure: numerous special adaptations of enzymes and membranes Food supply: must cope with the scarcity of food, its low energy content, and the risk of being detected. Food sources include land runoff, molts, fecal pellets, “marine snow”, dissolved organic matter, bacteria, vertical migrators Reproduction: mates are infrequently encountered; must have special means of communication (while reducing risk of predation)
SPEFICIC EXAMPLES OF ADAPTATIONTO THE DEEP SEA • Retain low metabolic rates (“float and wait”) • Eat large meals if available; mouths and digestive capacity are large • Use bioluminescence cautiously; lures can be used • Have opaque linings to the digestive tracts • For mating – some species have parasitic males • Large size may be an adaptation to hold more food, extend life span, and escape predation.
BIOLOGICAL ADAPTATION TO PRESSURE Biological Effects of Pressure Water is essentially incompressible Effects on gas-filled spaces can be severe All biochemical effects result from volumechange (1) Hydration (2) Dissociation (3) Polymerization/Subunit dissociation (4) Enzyme kinetics (activation volumes)
BIOLOGICAL ADAPTATION TO PRESSURE Physiological processes affected by pressure: (1) High-pressure neurological syndrome (HPNS) (2) Membrane fluxes (effects on ATPases) (3) Muscle contraction (cytoskeletal effects) (4) Synaptic transmission (generally inhibited) (5) Membrane fluidity
EFFECTS OF PRESSURE ON ENZYMES(2) Km values Ligand-binding events often involve changes in conformation and hydration, leading to increased volume Pressure adaptation may require only minor sequence change Pressure adaptation often leads to greater protein stability (resistance to denaturation) Pressure-adapted systems often have lower rates of catalysis
RESPIRATION RATES OF DEEP-SEA CRUSTACEANS Note that in bothfish and crustaceans, aerobic metabolic rates (and presumably typical anaerobic rates as well) decrease considerably with habitat depth.
COMMUNITES OF HYDROTHERMAL VENTS Hydrothermal vents represent very unusual deep-sea benthic habitats because they are sites where energy is abundant, due to chemicals supplied by “black smokers” – sources of abundant mineral sulfur.
COMMUNITES OF HYDROTHERMAL VENTS (2) The ultimate source of energy is H2S, which is oxidized by bacteria. The energy thus derived is used to operate the Calvin-Benson cycle of carbon fixation.
COMMUNITES OF HYDROTHERMAL VENTS (3) Sulfide is highly toxic at µM concentrations (it poisons cyt-c). Tubeworms (Riftia) detoxify it by binding it to Hb. Other vent organisms have various sulfide-binding proteins. Most vent animals contain endosymbiotic bacteria, which actually produce their nutrients.
COMMUNITES OF HYDROTHERMAL VENTS (4) An additional problem faced by thermal vent organisms is the extreme transience of the vent habitat; any one site may have a lifetime measured in tens of years. Thus, efficient dispersal and navigation by larvae is essential. (Photo: Bythograea thermydron)