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.