Ch. 16

• Physical factors that affect marine life:
• Light:

  • Photic zone: uppermost layer reaching about 100 meters down
  • Euphotic zone: where most biological productivity occurs, allowing marine autotrophs to capture enough sunlight for photosynthesis
  • Disphotic zone: light present but not bright enough for photosynthesis
  • Aphotic zone: permanently dark layer beneath the photic zone
• Classification of Marine Environments:
• Pelagic zone: open water

  • Neritic zone: near shore over continental shelf
  • Oceanic zone: deep water beyond continental shelf
  • Epipelagic zone: 0-200m deep, receives enough light for photosynthesis
  • Mesopelagic: 200-1000m deep, receives very little light
  • Bathypelagic: 1000-4000m deep, receives no sunlight
  • Abyssopelagic: 4000-6000m deep with near freezing water temps
• Marine Communities:
• Community: many populations of organisms interacting at a particular location

  • Producers, consumers, decomposers, etc.
  • Population: group of organisms of the same species occupying a specific area
  • Location of a community & populations depend on physical & biological characteristics of the living space
  • Dependent on energy availability
  • Photosynthesis or chemosynthesis
• Importance of the ocean:
• Ecosystem services provided by the ocean:

  • Carbon sink, source of oxygen, temperature buffering, global climate control
  • Carbon Sink: carbon dioxide dissolves into the ocean, taken in by producers and coral
  • Source of oxygen: phytoplankton release oxygen through photosynthesis
  • Temperature buffering: water's high heat capacity
  • Global climate control: regulates long term climate
• Habitat and Niche:
• Biotic Factors:
• Habitat: natural environment where an organism lives

  • Niche: an organism's role within an ecosystem
  • Feeding relationships, spatial relationships, temporal relationships
• Ecosystem: living organisms and their environment

  • Biotic Factors: living parts of an ecosystem including competition, symbioses, predation, disease
• Competition:
• Competition types:

  • Intra-specific: between individuals of the same species
  • Inter-specific: between members of different species
  • Can lead to overlap between ecological niches
• Abiotic Factors:
• Abiotic Factors: non-living parts of an ecosystem including salinity, temperature, pH, oxygen concentration, carbon dioxide concentration, light availability, turbidity, wave/tide action, nutrient availability, exposure to air
• Abiotic - Temperature and Salinity:
• Stenothermal: organisms with narrow temperature tolerance

  • Eurythermal: organisms with wide temperature tolerance
  • Stenohaline: organisms requiring stable saline environment
  • Euryhaline: organisms with wide salinity tolerance
• Distribution of Organisms:
• Population density, rare vs. dominant individuals, biodiversity in different habitats

  • Random, clumped, uniform distribution patterns
• Biodiversity:
• Measure of species, genetic, and ecosystem diversity

  • Explored at species, genetic, and ecological levels
• Importance of marine biodiversity:
• Maintaining stable ecosystems, protection of physical environment, climate control, providing food sources, source of medicine
• The Benthos:
• More than 98% of known marine species are benthic

  • Benthic communities include rocky intertidal, sandy/cobble beach, salt marsh & estuary, coral reef, deep sea floor, hydrothermal vent communities
• Rocky Intertidal Community:
• Area between high and low tides

  • Pros: abundant food & light, high biodiversity
  • Cons: tough place to live, adaptations for fluctuating temperatures and salinity, wave action, exposure to air
• Competition in the Rocky Intertidal Zone:
• Example of barnacles competing for space on rocks in the intertidal zone
• Competition in the Rocky Intertidal Zone:

  • 2 species of barnacle compete for space on rocks in the intertidal zone
  • Larger barnacle (Balanus) is better at taking over space than the smaller one
  • Smaller barnacle (Chthamalus) can survive out of water better than the larger one
  • Result: Larger barnacle dominates lower down, while the smaller one dominates higher up
• Rocky Intertidal Community:

  • Zonation is a distinct feature of this community
  • Different species arrange themselves into distinct horizontal bands or zones within the intertidal zone according to their ability to withstand desiccation and inundation
• Rocky Shores:

  • Support a wide range of organisms
  • Relatively stable substrate of large rocks and stones provides a firm surface for attachment of many species of algae and animals such as mollusks and cnidarians
  • Rock pools or tide pools retain water when the tide retreats and may support a wide range of different species
  • Longer the tide is out, the warmer and saltier the tide pools become due to shallowness of the water and evaporation
• • Lack of oxygen becomes a problem due to increasing temperatures and salinity forcing dissolved oxygen to leave the water while organisms within the pool are using up the oxygen
• • Adaptations: Blue mussels use byssal threads to attach to rocks
  • Lower Shore:
  • Area usually covered with water except during the lowest spring tides
  • Examples: Sea stars and sea anemones
  • Few adaptations for living outside water
• Intertidal Zones:

  • Splash Zone:
  • Area just above the high tide mark
  • Examples: Periwinkle and Limpets
  • Adaptations: Periwinkles can survive for days without food or water by closing themselves into their shell storing just enough water in their gills for gas exchange
  • Upper Shore:
  • Portion of shore only submerged during high tides
  • Examples: Chitons and crabs
  • Adaptations: Chitons have a muscular foot that can clamp down hard onto rocks to prevent waves
  • Middle Shore:
  • Exposed to air twice a day at low tide
  • Examples: Blue mussels and abalone
• Sandy & Cobble Beach Communities:

  • Beaches are physically demanding
  • Pros: Less competition between species, abundant plankton, detritus, and light
  • Cons: Higher energy, loose sand that is unstable
  • Porous substrate allows for passage of air and water
  • Adaptations needed to withstand desiccation and inundation
• Salt Marsh & Estuary Community:

  • Pros: Lower energy, gentler slopes, finer sediments, more stable, rich in nutrients, abundant sunlight
  • Cons: Fluctuating salinity and temperature, vulnerable to pollution and urban development
• Coral Reef Community:

  • Created by coral animals
  • Corals secrete skeletal structures of calcium carbonate
  • Coral reefs have the greatest biodiversity of any marine community
• Deep Sea Floor Community:

  • Many species adapted to eating detritus
  • Deep sea organisms have slow metabolism and do not require much food
  • Physical constraints include darkness, cold, high pressure, high oxygen, and slow currents
  • Diversity is much greater than expected