Ocean Pollution & Marine Debris – Comprehensive Study Notes

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.

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.

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.

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.

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.

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.

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.

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).

> \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.

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.

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.