Ocean Pollution & Marine Debris – Comprehensive Study Notes

Scope and Scale of Ocean Pollution

• Each year billions of pounds of trash and pollutants enter the ocean.
  • Expressed numerically: > 1\times10^9 \text{ lb yr}^{-1} of debris.
• Fates of debris once in the marine environment
  • Washed ashore by waves/tides → litters beaches.
  • Sinks to the seafloor, often out of casual sight but still ecologically active.
  • Consumed by marine organisms that mistake debris for food.
  • Aggregates within rotating current systems (ocean gyres) forming “garbage patches.”
• Visual hotspot example: Kanapou Bay, Kahoʻolawe (Hawai‘i)
  • Litter items observed: plastic detergent bottles, crates, buoys, combs, single-use water bottles.
  • Highlights land-to-sea transport even to remote shorelines.

Primary Sources of Marine Pollution

• Human activities both coastal and far inland are dominant contributors.
• Non-point source pollution (runoff-driven, diffuse)
  • Septic tanks, vehicles & roadways, agricultural fields, livestock ranches, timber harvest sites, suburban lawns.
  • Carries fertilizers, pesticides, oils, sediments, and plastics into waterways.
• Point source pollution (single, identifiable discharge)
  • Oil & chemical spills, ruptured pipelines, faulty industrial effluents, damaged wastewater-treatment outfalls.
  • Less frequent but capable of acute, large-scale damage.
• Ocean-based sources
  • Derelict or abandoned fishing gear, lost cargo, vessel discharges.
• Natural extreme events that mobilize debris: hurricanes, tsunamis, floods.

Nutrient Enrichment, Algal Blooms, and Hypoxia

• Essential plant nutrients (nitrogen, phosphorus) become pollutants when concentrations are excessive.
  • Over-fertilized runoff triggers algal blooms.
• Two key bloom categories
  • General algal bloom → can shade seagrasses & deplete oxygen on decay.
  • Harmful algal blooms (HABs) / “red tides” → certain species grow explosively and release potent biotoxins.
  • Can poison fish, shellfish, marine mammals, and sometimes humans.
• Oxygen dynamics
  • Sinking algae + bacterial decomposition → \text{O}_2 consumption.
  • Process equation (simplified respiration): C6H{12}O6 + 6O2 \rightarrow 6CO2 + 6H2O + \text{energy}.
  • Leads to hypoxia (low-oxygen) or dead zones where mobile fauna flee or perish.

Monitoring & Forecasting Technologies

• NOAA Harmful Algal Bloom Monitoring System delivers near-real-time data to agencies and the public.
  • Enables proactive beach closures, shellfish harvest advisories, and health warnings.
• Ecological Forecasting models integrate HAB data with physical drivers to predict ecosystem change and socioeconomic impacts.

Persistent Organic & Emerging Chemical Pollutants

• PFAS (Per- & Polyfluoroalkyl Substances)
  • Nicknamed “forever chemicals” for extreme resistance to biodegradation.
  • Detected in ground, surface, and drinking waters.
  • 2022 Hollings internship: Makayla Neldner assessed two PFAS molecules’ effects on larval grass shrimp (\textit{Palaemon pugio}) life cycle.
• Heavy metals, hydrocarbons, and microplastics bioaccumulate and biomagnify in food webs.
  • Consequence: seafood safety risks for humans and wildlife.

Marine Debris: Definition, Types, and Impacts

• NOAA definition: Any persistent solid material human-made, intentionally or unintentionally, directly or indirectly disposed of or abandoned into the marine environment or Great Lakes.
• Size spectrum
  • Microplastics < 5\,\text{mm}.
  • Macro-debris: buoys, nets, derelict vessels.
• Biological impacts
  • Ingestion → blockage, malnutrition, chemical exposure.
  • Entanglement → injury, drowning, impaired mobility.
  • Habitat damage (e.g., coral abrasion, seagrass scouring).
• Navigational and human-safety hazards.
• Socioeconomic costs: derelict nets compete with active fishing, beach-tourism losses.
• Example research: Hollings scholar Eleanor Meng quantified trash incorporation in songbird nests near vs. far from a visitor center (St. Jones Reserve, Delaware), illustrating terrestrial-to-avian pathway of marine debris.

Garbage Patches & Ocean Gyres

• Misconception: not floating “islands” but diffuse zones with elevated particle density from surface to seabed.
• Formed by large clockwise/counter-clockwise current systems (gyres) that converge floating material toward the center.
  • Five major subtropical gyres
  • 1 Indian Ocean gyre.
  • 2 Atlantic gyres (North & South).
  • 2 Pacific gyres (North & South).
• Patch boundaries continually shift under wind and current variation.
• Materials originate mostly from land via river outflow & coastal runoff, supplemented by lost fishing gear.

Legislative & Policy Framework

• Marine Debris Act
  • Promotes international collaboration, authorizes cleanup/response, coordinates federal agency actions.
• Save Our Seas Act of 2018
  • Reauthorized and amended Marine Debris Act; enhanced funding and partnerships.
• Additional statutes cover oil spill response (OPA 1990), water quality (Clean Water Act), hazardous substances (CERCLA).

Seafood Safety & Human Health

• > \tfrac{1}{3} of U.S. shellfish-growing waters are impaired by coastal pollution.
• Contaminant pathways
  • Bioaccumulation of heavy metals (Hg, Pb, Cd) in fish tissue.
  • Microplastic ingestion by filter feeders (e.g., mussels, oysters) and planktivorous fish.
• NOAA conducts nationwide seafood contamination monitoring and disseminates consumer guidance via the Sustainable Seafood portal.

Education, Outreach, and Citizen Solutions

• Everyone—coastal or inland—is part of both problem & solution.
• NOAA Marine Debris Program provides curricula, citizen-science projects, beach-cleanup toolkits, and multimedia resources.
• Individual actions highlighted
  • Reduce, Reuse, Recycle plastic products.
  • Properly maintain septic systems & minimize fertilizer use.
  • Participate in local water-quality monitoring & habitat restoration.
  • Support policy initiatives addressing single-use plastics and enhanced waste management.

Ethical, Philosophical & Practical Considerations

• Intergenerational responsibility: today’s waste persists for decades-centuries, affecting future ecosystems and human communities.
• Environmental justice: coastal and subsistence communities often bear disproportionate burdens of seafood contamination and beach pollution.
• Precautionary principle: advocate upstream pollution prevention over downstream cleanup for cost-effectiveness and ecological integrity.