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Overview of Marine Biology Concepts

Nov 18, 2024

Marine Biology Lecture Notes

Defining Life

  • Biological Criteria: Growth, metabolism, movement, reproduction, reaction to stimuli.
  • Common Characteristics:
    • Single origin of evolution.
    • Shared mechanisms for energy capture, protein synthesis, and genetic information transfer.

Evolutionary Principles

  • Genetic changes drive new traits through natural selection.
  • Key Milestones:
    • Darwin & Wallace (1858): Evolutionary theory.
    • Mendel's genetics rediscovered (1910).
    • Modern Synthesis (1930s-1953).
    • DNA structure discovered (1953).

Biomolecules

  • Composed of C, N, P, S, O, H.
  • Functions include:
    • Energy storage
    • Information encoding
    • Structural support
    • Catalysis
    • Transport
    • Defense
    • Regulation
    • Movement

Organization of Life

  • Cell Theory:
    • Prokaryotes: No organelles, nucleoid DNA.
    • Eukaryotes: Compartmentalized organelles, nucleus with DNA.
  • Central Dogma: DNA -> RNA -> Protein.

DNA and RNA

  • DNA: ATCG bases, stores genetic info, compacted in chromosomes.
  • RNA: AUCG bases, translates DNA into proteins.
  • Protein Encoding: Codons (3 nucleotides) map to 1 amino acid, redundancy for error tolerance.

Metabolism

  • Autotrophy: Photosynthesis, chemolithoautotrophy.
  • Heterotrophy: Ingestion, parasitism, saprophytism.
  • Energy Flow: Gross Primary Productivity (GPP) – Respiration = Net Primary Productivity (NPP).

Food Webs

  • Classic: Phytoplankton -> Copepods -> Fish.
  • Microbial Loop: Cycling of organic carbon via microorganisms.

Biogeochemical Cycles

  • Elements (C, N, P) cycle between living organisms and Earth systems.
  • Marine Impact: Light, nutrients, salinity, pH affect marine life.

Mass Extinctions

  • End Permian (96% marine species lost).
  • End Cretaceous (dinosaur extinction).

Key Takeaways

  • Life evolved through genetic and environmental adaptation.
  • Energy flow and element cycling are critical for ecosystems.
  • Rapid environmental changes threaten biodiversity.

Classic Food Web vs. Microbial Loop

  • Classic: Carbon flows from phytoplankton -> zooplankton -> fish.
  • Microbial Loop: Recycles organic carbon via microorganisms.

Primary Productivity

  • Light/Nutrients Limitations:
    • Key nutrients: Nitrate, phosphate, silicate, trace metals (Fe, Co, Ni, Zn).
    • Photosynthesis in the euphotic zone.
  • Phytoplankton Adaptations:
    • Seasonal succession and diverse pigments.

Phytoplankton Diversity

  • Cyanobacteria: Major photosynthesizers, nitrogen fixation.
  • Diatoms: Silicon frustules, diverse morphologies.
  • Coccolithophores: Calcium carbonate plates, sensitive to pH.
  • Dinoflagellates: Varied metabolism, harmful algal blooms.

Carbon Pumps

  • Biological Carbon Pump (BCP):
    • Organic carbon sinks to deep ocean.
    • POC: Cells, remains, polysaccharides.
    • DOC: Dissolved organics.
  • Microbial Carbon Pump (MCP): Converts labile carbon to refractory DOC.

Marine Zooplankton

  • Microzooplankton: Major grazers of phytoplankton.
  • Mesozooplankton: Diel vertical migration, diapause.

Marine Bacteria and Archaea

  • Key Groups:
    • SAR11: Abundant bacteria.
    • Cyanobacteria.
    • Archaea: Nutrient-poor waters.
  • Adaptations: Free-living vs. particle-associated.

Marine Viruses

  • Biogeochemical Role:
    • Viral shunt redirects organic carbon to DOM pool.
    • Lytic and Lysogenic cycles.
    • Facilitate horizontal gene transfer.

Measurement and Impact

  • Primary Productivity:
    • Light/dark incubations, carbon isotopes, satellite data.
  • Key Insights: Viruses and microbial processes drive nutrient cycling.

Key Marine Animal Phyla

  1. Porifera (Sponges)
    • No true tissues, radial symmetry.
  2. Cnidaria (Cnidarians)
    • Stinging cells, radial symmetry.
  3. Mollusca (Mollusks)
    • Fleshy mantle, muscular foot, radula.
  4. Annelida (Segmented Worms)
  5. Arthropoda (Arthropods)
    • Segmented body, exoskeleton.
  6. Echinodermata
    • Radial symmetry, hydrostatic skeleton.
  7. Chordata (Chordates)
    • Notochord, dorsal nerve cord.

Marine Communities

  • Definitions:
    • Population, community, ecosystem, niche.

Abiotic and Biotic Factors in Coastal Ecosystems

  • Abiotic: Wave action, tides, light, oxygen, nutrients, salinity.
  • Biotic: Competition, predation, shading, toxins.

Key Coastal Ecosystems

  1. Rocky Intertidal Zones
  2. Kelp Forests
  3. Estuaries
  4. Mangroves
  5. Seagrass Meadows
  6. Coral Reefs
  7. Oyster Reefs

Ecological Processes

  • Population Dynamics:
    • Carrying Capacity, growth types.
  • Larval Ecology: Planktotrophic vs. lecithotrophic.

Human and Ecosystem Connectivity

  • Coastal ecosystems provide ecosystem services.

Key Features of Polar Regions

  • Arctic vs. Antarctic:
    • Arctic: Shallow, landlocked.
    • Antarctic: Landmass, dynamic currents.

Arctic Ecosystem

  • Sea Ice: Reduced by ~50%.
  • Food Web: Primary producers and consumers.
  • Seasonal Biogeochemistry: Winter vs. Spring/Summer.
  • Climate Change Impacts: Rising temperatures.

Antarctic Ecosystem

  • Sea Ice vs. Ice Sheet: Variability and decline.
  • Unique Physical Oceanography: Upwelling supports productivity.
  • Food Web: Krill as a keystone species.

Marine Protected Areas (MPAs)

  • Purpose: Conservation and sustainable use.
  • Ross Sea MPA: Covers 1.55 million km².

Physical Characteristics of the Deep Sea

  • Low temperature, high pressure, low light.
  • Extreme environments: Abyssal plains, hydrothermal vents.

Adaptations to Deep Sea Life

  • Biochemical: Pressure-resistant enzymes.
  • Morphological: Large eyes, bioluminescence.
  • Marine Mammals: Collapsible lungs, bradycardia.

Deep Sea Ecosystems

  1. Abyssal Plains
  2. Hydrothermal Vents
  3. Cold Seeps and Brine Pools
  4. Seamounts

Bioluminescence

  • Roles and chemical basis.

Ecological Connectivity

  • Whale falls, cold seeps, and hydrothermal vents link habitats.