Marine Life and the Marine Environment

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Marine Life and the Marine Environment
Fig. 12.5
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Physical and Chemical Factors

• Solar energy availability
• Salinity variations
• Water depth
• Temperature variations with depth
• Pressure variations with depth
• Nutrient availability and distribution
• Dissolved oxygen variations
• pH variations

3
Sunlight Penetration

• Euphotic
• Disphotic
• Aphotic

Euphotic zone (0 to 200 meters depth) Disphotic
zone (200 to 1000 meters depth) Aphotic zone (gt
1000 meters depth)
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Fig. 1.3cd
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Salinity of sea water The average salinity of
sea water is 35 grams dissolved salt / kg sea
water. Also listed as 3.5 by weight or 35
p.p.t.(parts per thousand) or 35 o/oo (parts per
mil). 99 of sea water is in the range 30 to 37
g/kg.
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Main divisions of the marine environment

• Pelagic (open ocean)
• Neritic (lt 200 m water depth)
• Oceanic
• Benthic (sea floor)
• Supralittoral (above tidal influenced region)
• Subneritic (continental shelf)
• Suboceanic (continental slope to abyssal plain)

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Pelagic environments

• Epipelagic
• Mesopelagic
• Bathypelagic
• Abyssopelagic

Fig. 12.19
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Pelagic environments

• Dissolved O2 minimum layer about 700-1000 m
• Nutrient maximum at about same depths
• O2 content increases with depth below

Fig. 12.20
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Benthic environments

• Supralittoral
• Subneritic
• Littoral
• Sublittoral
• Inner
• Outer
• Suboceanic
• Bathyal
• Abyssal
• Hadal

Fig. 12.19
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Marine Life Overview

• More than 250,000 identified marine species
• Most live in sunlit surface seawater (Euphotic
  zone)
• Species success depends on ability to
• Find food/nutrients
• Avoid predation
• Reproduce
• Cope with physical barriers to movement

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Classification of living organisms

• Physical characteristics
• Three domains
• Archaea
• Bacteria
• Eukarya

Fig. 12.1
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Classification of living organisms

• Physical characteristics
• Five kingdoms
• Monera
• Protoctista
• Fungi
• Plantae
• Animalia

Fig. 12.1
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Five kingdoms

• Monera simplest organisms, single-celled
• Cyanobacteria, heterotrophic bacteria, archaea
• Protoctista single and multicelled with nucleus
• Algae, protozoa
• Fungi
• Mold, lichen
• Plantae multicelled photosynthetic plants
• Surf grass, eelgrass, mangrove, marsh grasses
• Animalia multicelled animals
• Simple sponges to complex vertebrates

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Taxonomic classification

• Systemized classification of organisms
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species
• Fundamental unit
• Population of genetically similar, interbreeding
  individuals

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Classification by habitat and mobility

• Plankton (floaters)
• Nekton (swimmers)
• Benthos (bottom dwellers)

Fig. 12.6
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Plankton

• Most biomass on Earth consists of plankton
• Phytoplankton
• Autotrophic (an organism capable of synthesizing
  its own food from inorganic substances, using
  light or chemical energy)
• Zooplankton
• Heterotrophic (An organism that cannot synthesize
  its own food and is dependent on complex organic
  substances for nutrition)
• Bacterioplankton
• Bacteria that live in the open waters of the
  ocean
• Virioplankton
• virioplankton communities are composed
  principally of bacteriophages and, to a lesser
  extent, eukaryotic algal viruses

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Plankton

• Holoplankton
• Entire lives as plankton
• Meroplankton
• Part of lives as plankton
• Juvenile or larval stages
• Macroplankton
• Large floaters such as jellyfish or Sargassum
• Picoplankton
• Very small floaters such as bacterioplankton

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Nekton

• Independent swimmers
• Most adult fish and squid
• Marine mammals
• Marine reptiles

Fig. 12.3
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Benthos

• Epifauna - live on surface of sea floor
• Infauna - live buried in sediments
• Nektobenthos - swim or crawl through water above
  seafloor
• Most abundant in shallower water often because
  of sunlight penetration

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Hydrothermal Vent Biocommunities

• Abundant and large deep-ocean benthos
• Discovered in 1977
• Associated with hot vents
• Bacteria-like archaeon produce food using heat
  and chemicals (autotrophic)

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Number of marine species

• More land species than marine species
• Ocean relatively uniform conditions
• Less adaptation required, less speciation
• Marine species overwhelmingly benthic rather than
  pelagic

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Adaptations of marine organisms

• Physical support
• Buoyancy
• How to resist sinking
• Different support structures in cold (fewer)
  rather than warm (more appendages) seawater
• Smaller size

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Adaptations to marine life

• Appendages to increase surface area
• Oil in micro-organisms to increase buoyancy

Fig. 12.9
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Adaptations to marine life

• Streamlining important for larger organisms
• Less resistance to fluid flow
• Flattened body
• Tapering back end

Fig. 12.10
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Adaptations to marine life

• Narrow range temperature in oceans
• Smaller variations (daily, seasonally, annually)
• Deep ocean nearly isothermal

Fig. 12.11
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Adaptations to marine life

• Cold- versus warm-water species
• Smaller in cooler seawater
• More appendages in warmer seawater
• Tropical organisms grow faster, live shorter,
  reproduce more often
• More species in warmer seawater
• More biomass in cooler seawater (upwelling)

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Adaptations to marine life

• Stenothermal
• Organisms withstand small variation in
  temperature
• Typically live in open ocean
• Eurythermal
• Organisms withstand large variation in
  temperature
• Typically live in coastal waters

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Adaptations to marine life

• Stenohaline
• Organisms withstand only small variation in
  salinity
• Typically live in open ocean
• Euryhaline
• Organisms withstand large variation in salinity
• Typically live in coastal waters, e.g., estuaries

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Adaptations to marine life

• Extracting minerals from seawater
• High concentration to low concentration
• Diffusion
• Cell membrane permeable to nutrients, for example
• Waste passes from cell to ocean

Fig. 12.12
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Adaptations to marine life

• Osmotic pressure
• Less concentrated to more concentrated solutions
• Isotonic
• Hypertonic
• Hypotonic

Fig. 12.13
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Marine versus freshwater fish
Fig. 12.14
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Adaptations to marine life

• Dissolved gases
• Animals extract dissolved oxygen (O2) from
  seawater through gills

Fig. 12.15
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Adaptations to marine life

• Waters transparency
• Many marine organisms see well
• Some marine organisms are nearly transparent to
  avoid predation

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Adaptations to marine life

• Camouflage through color patterns
• Countershading
• Disruptive coloring

Fig. 12.17a
Fig. 12.17b
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Adaptations to marine life

• Water pressure
• Increases about 1 atmosphere (1 kg/cm2) with
  every 10 m (33 ft) deeper
• At 1000 m, pressure 100 atm (100 kg/cm2)
• Many marine organisms do not have inner air
  pockets
• Collapsible rib cage (e.g., sperm whale)