biology 457 657 physiology of marine estuarine animals
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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.

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biology 457 657 physiology of marine estuarine animals

BIOLOGY 457/657PHYSIOLOGY OF MARINE & ESTUARINE ANIMALS

March 8, 2004

Physiological Adaptation to the Deep Sea

features of 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 sea3
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
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 adaptation to the deep sea
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 adaptation to the deep sea
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 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 pressure16
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 k m values
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
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
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
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
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
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)

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