Lecture 32: Human Impacts on the Ocean Final

What are impacts of unregulated marine tourism?

Physical Damage, Pollution, and Disturbance

What are impacts of coastal development?

Habitat Destruction, Pollution, Runoff, and Altered Hydrology

What are impacts of trawling and boating?

Trawling: Seafloor Destruction, Bycatch, and Sediment Resuspension

Boating: Chemical Pollution, Physical Damage, and Invasive Species

What is eutrophication? What characteristics of poor water quality are associated with eutrophication?

The excessive accumulation of nutrients (primarily nitrogen and phosphorus) in a body of water.

Harmful Algal Blooms (HABs), Depleted Dissolved Oxygen (DO), and Increased Turbidity

What is hypoxia? What is anoxia?

Hypoxia: A condition in an aquatic environment where the concentration of dissolved oxygen (DO) is abnormally low, typically defined as less than 2 mg/L. This low level of oxygen creates physiological stress for most marine life.

Anoxia: An extreme condition where dissolved oxygen is completely absent (DO = 0 mg/L). These environments are lethal to most aerobic organisms.

What is a "dead zone"?

An area of the ocean or a large lake where bottom water is severely depleted of oxygen (hypoxic or anoxic), forcing mobile organisms to leave and killing sessile (immobile) organisms like mussels and worms.

What causes the dead zone in the Gulf of Mexico?

Massive quantities of nutrient runoff.

How does hypoxia affect food webs?

Mortality, Displacement, Altered Predator-Prey Dynamics, and Habitat Loss

What are impacts of sewage pollution?

Pathogen Exposure, Eutrophication, and Ecosystem Damage

What are the short-term impacts of oil pollution?

Physical Smothering: Thick, heavy oil coats birds, mammals, and intertidal organisms, causing hypothermia, poisoning from grooming, and mechanical injury (e.g., suffocating filter feeders).

Acute Toxicity: Volatile, lighter fractions of the oil are highly toxic and can quickly poison marine life, especially eggs, larvae, and organisms in the water column.

What are the long-term impacts of oil pollution?

Chronic Toxicity: Heavier, non-volatile components like Polycyclic Aromatic Hydrocarbons (PAHs) persist in sediments for years, causing sub-lethal (chronic) effects like reduced growth, impaired reproduction, compromised immune function, and liver damage in fish and invertebrates.

Habitat Contamination: Oil trapped in sediments of low-energy environments (like salt marshes) can be a continuous source of contamination.

Define bioaccumulation.

The buildup of a contaminant in an individual organism over its lifetime, where the rate of uptake (from all sources like water, food, and sediment) is greater than the rate of excretion.

Defined biomagnification.

The increase in concentration of a substance in animal tissues at successively higher trophic levels (up the food chain).

Why is bioaccumulation and biomagnification important in understanding the ecotoxicology of a pollutant?

They are crucial because they explain how low concentrations of persistent pollutants (like POPs and methylmercury) in the water can lead to extremely high, toxic, and even lethal concentrations in top predators (such as tuna, sharks, or humans), making these apex species the most vulnerable.

What are the impacts of heavy metal pollution like methylmercury?

Neurotoxicity, Organ Damage, Reproduction, and Behavioral Effects.

What are persistent organic pollutants? What are these chemicals used for? What are ecotoxicological impacts of POPs?

Toxic chemicals that possess four characteristics: they are Persistent (resistant to degradation), Bioaccumulate, Toxic, and transported over Long Distances.

They are often semi-volatile. Historically used as pesticides (e.g., DDT, endrin) and in industrial processes (e.g., PCBs, dioxins).

They act as endocrine disruptors, interfering with the hormonal systems of animals, causing reproductive disorders, immune system suppression, and developmental and neurological problems.

What is the grasshopper effect?

The geochemical process by which semi-volatile chemicals like POPs are transported from warmer to colder regions.

Why do Arctic mammals have extremely high amount of toxic materials in their tissues?

Grasshopper Effect and Biomagnification

What are contaminants of emerging concern? What types of chemicals are classified as CECs? What are the ecotoxicological impacts of CECs?

Synthetic or naturally occurring chemicals that are not routinely monitored in the environment but have the potential to cause adverse ecological and/or human health effects.

-Pharmaceuticals

-Personal Care Products

-Industrial Chemicals

-Microplastics

CECs are often found at low concentrations but cause chronic, sub-lethal effects, such as acting as endocrine disruptors (affecting reproductive development), altering behavior, and impairing immune function in marine life.

Why is plastic in the ocean such a concern?

Because of its persistence (it never truly disappears, only fragments), its sheer volume, and the wide range of physical and chemical harm it causes. It leads to entanglement, ingestion (causing starvation by filling the stomach), and acts as a vector for transporting invasive species and other attached pollutants.

What ecotoxicant traits does plastic display?

Persistence, Physical Toxicity, Chemical Leaching, and Contaminant Vector

What are impacts of thermal pollution?

Reduced Dissolved Oxygen, Metabolic Stress, and Ecological Shifts

What are impacts of radioactive pollution?

Feed Web Contamination and Genetic Damage

What are impacts of noise pollution?

Communication Interference, Behavioral Alteration, and Physical Trauma

What are conservation efforts to protect nearshore marine organisms and habitats?

Establishment of Marine Protected Areas (MPAs), Habitat Restoration, Improved Coastal Wastewater Treatment, and Regulation of Coastal Development

What are conservation efforts to protect open-water marine organisms and habitats?

Sustainable Fisheries Management, International Agreements, Vessel Traffic Management, Addressing Climate Change and Ocean Acidification