Comprehensive Notes on Marine Biology and Oceanography

Introduction to Marine Environments and Biology

The Vast, Unexplored Ocean

• Over $70\%$ of the Earth's surface is covered by water.

• The majority of this vast marine environment remains unexplored.

Recent Discoveries and Mounting Challenges

Exciting Discoveries

• New Galapagos Coral Reef Discovered: An example of ongoing discoveries in marine biology.

• 1,600-foot Coral Reef in Great Barrier: One of the significant finds of the century, highlighting the unexplored nature of the ocean.

Sad News: Historic Ocean Heat Wave and Coral Bleaching

• Historic Ocean Heat Wave in Florida: NOAA (National Oceanic and Atmospheric Administration) and partners are actively working to rescue remaining Florida corals.

  • Degree Heating Weeks (DHW): A metric used to quantify thermal stress accumulated in an area over time, typically $12$ weeks.

  • The formula is represented as $\text{DHW} = \text{how much heat stress has accumulated in an area over the past } 12 \text{ weeks.}$

• 4th Global Mass Bleaching Event (2024): Declared by NOAA and ICRI (International Coral Reef Initiative), indicating widespread thermal stress on coral reefs globally.

Contrasting Terrestrial and Marine Environments

Fundamental Differences and Biological Consequences

Marine and terrestrial environments present distinct physical conditions that necessitate specific biological adaptations. Key differences are observed in:

• Seawater/Air Density: Seawater is approximately $830$ times denser than air.

  • Biological Consequence: Higher density reduces the energetic cost of support (e.g., skeletons for buoyancy) and offers greater resistance to movement, favoring streamlined body shapes.

• Viscosity: Seawater is about $60$ times more viscous (or "sticky") than air.

  • Biological Consequence: Increased drag on organisms, impacting locomotion; also aids in suspension for small organisms.

• Diffusion Coefficient: The diffusion coefficient in water for gases like oxygen is about $10^{-4}$ lower than in air, leading to lower oxygen availability in aquatic environments.

  • Biological Consequence: Organisms require efficient respiratory systems (gills) and may face challenges in low-oxygen (hypoxic) environments.

• Light Attenuation: Light penetration in water is significantly less, ranging from $100$ to $10^7$ times less than in air.

  • Biological Consequence: Photosynthesis is restricted to the upper layers (photic zone); deeper organisms adapt to darkness (e.g., bioluminescence, enhanced senses).

• Electrical Conductivity: Seawater has a much higher electrical conductivity, approximately $2 \times 10^{10}$ times that of air.

  • Biological Consequence: Useful for electroreception in some marine animals; can also impact electrical signals from organisms.

• Sound (Speed): Sound travels approximately $4$ times faster in water than in air.

  • Biological Consequence: Marine animals rely heavily on sound for communication, navigation, and hunting.

• Sound (Attenuation): Sound attenuation in water is approximately $10^{-4}$ lower than in air, meaning sound travels much farther in water.

  • Biological Consequence: Long-distance communication and echolocation are highly effective.

Reference: Webb (2012) provides informative comparisons between marine and terrestrial systems.

Estuaries: Where Freshwater Meets the Sea

Characteristics and Salinity Gradients

• Estuaries: Transition zones where freshwater from rivers mixes with saltwater from the ocean.

  • Examples: Hudson River, Delaware Bay, Chesapeake Bay.

• Salinity: Measured in parts per thousand ($\text{ppt}$ or extperthousand}).

  • Freshwater: $0 \text{ ppt}$.

  • Brackish Water: $5-18 \text{ extperthousand}$.

  • Seawater: Generally $35 \text{ ppt}$ or extperthousand} (composed of $96.5\%$ water and $3.5\%$ salts, primarily sodium chloride (NaCl)).

• Organisms: Some species (e.g., eels, salmon) are euryhaline, meaning they can tolerate a wide range of salinities and may span the entire freshwater-to-sea gradient over their life cycles.

Importance of Estuaries and Marshes (Ecosystem Services)

• Blue Crab (\textit{Callinectes sapidus}) Lifecycle: Illustrates the ecological and commercial importance of estuaries.

  • Larval Development (Zoea, Megalops): Occurs in high-salinity oceanic waters.

  • Migration of Juveniles: Move into lower-salinity estuarine habitats.

  • Molting/Feeding: Occurs in brackish waters.

  • Adult Males & Females: Found across a range of salinities.

  • Mating: Often occurs around $24 \text{ extperthousand}$. Early to late pregnancy phases follow, with each female producing $2-8$ million eggs.

• Ecosystem Services: Benefits that healthy ecosystems provide to humans.

  • Storm Protection: Marshes and estuaries act as natural buffers, attenuating storm surges and protecting human property and lives.

    • Superstorm Sandy (2012) Impact: Illustrated significant post-storm changes in marsh environments, including buried vegetation, new gullies, filled ponds, and sand-covered marshes, demonstrating their protective role and vulnerability.

    • Debris resulting from storms can severely impact these sensitive ecosystems, as observed at the marsh at the Nike School in the Long Beach School District, requiring extensive removal efforts.

Marine Debris: A Global Crisis

• Definition: Rubbish from everyday lives that makes its way into the ocean.

• Journey: Travels over land, down streams, rivers, and storm drains to the ocean; once in the ocean, it can drift thousands of miles.

• Impacts:

  • Kills thousands of marine animals and seabirds annually.

  • Chokes coral reefs and smothers critical marine environments.

  • Contaminates beaches and recreation sites.

• **Statistics (from NOAA & Project AWARE):

  • Plastic Production: Annual plastic production and use has risen dramatically from $1.5$ million tons in $1950$ to $230$ million tons in $2009$.

  • Marine Litter Entry: Over $6$ million tons of marine litter may be entering our ocean every year.

  • Plastic Dominance: As much as $90\%$ of floating marine debris may be plastic.

  • Northern Fulmar Seabirds: Research showed that $95\%$ of dead, beached northern fulmar birds collected had plastic in their stomachs.

  • Northern Fur Seal Mortality: Between $50,000$ and $90,000$ northern fur seals are estimated to be dying every year due to entanglement in marine debris.

  • Plankton-Eating Fish: $35\%$ of plankton-eating fish found during a study in the North Pacific Central Gyre had ingested plastic.

  • Affected Species: More than $260$ marine species are reported to have been entangled in or to have ingested marine debris.

  • Seabed Accumulation: As much as $70\%$ of marine litter has been estimated to end up on the seabed.

• Responsibility: Everyone is responsible for preventing and clearing up marine debris.

• Solutions: Initiatives like Project AWARE encourage scuba divers to remove debris and log data to drive policy changes, alongside community action and local solutions.

Branches of Marine Science

Oceanography

• Geological Oceanography: Focuses on the structure of the sea floor, changes through time, creation of seafloor features, and the history of sediments deposited on it.

• Chemical Oceanography: Studies seawater, its chemical composition and properties, and the effects of pollutants.

• Physical Oceanography: Investigates waves, tides, and currents, the ocean-atmosphere relationship that influences weather and climate, and the transmission of light and sound in the oceans.

• Biological Oceanography: Has significant overlap with Marine Biology, specifically focusing on how marine life interacts with its environment.

Marine Biology

• The study of marine organisms, their life history, and their interactions.

• Major Components:

  • Functional Biology: How organisms work (physiology, anatomy).

  • Ecology: How organisms interact with each other and their environment.

  • Biodiversity: The variety of life forms and their distribution.

A Brief History of Marine Exploration

• Voyage of the Beagle (1831-1836): Charles Darwin's foundational work for evolutionary theory included extensive studies of marine species, notably barnacles (