GEOS103 EXAM 2

What is plastic made of?

Plastic is made from polymers created mainly from petroleum and natural gas.

What are the raw materials used to make plastic?

Crude oil and natural gas.

What happens to plastic when exposed to sunlight and saltwater?

It breaks down into smaller pieces called microplastics but does not fully biodegrade.

How long does plastic last in the ocean?

Hundreds to thousands of years depending on the type of plastic.

Is plastic pollution only a problem in oceans?

No, it is also a major problem in freshwater systems like rivers and lakes.

What are ways marine organisms are impacted by plastic?

Ingestion of plastic, entanglement, habitat damage, and chemical contamination.

Why is the chemical signature of plastic amplified in the ocean food web?

Plastics absorb and concentrate toxic chemicals which biomagnify as predators eat contaminated prey.

Are there impacts of plastic pollution on humans?

Yes, humans can ingest microplastics and associated toxins through seafood and water.

Is it better to tackle plastic pollution at the source or after it enters the ocean?

At the source, because preventing plastic waste is easier than removing it from the ocean.

What do current projects to solve plastic pollution focus on?

Reducing plastic production, improving recycling, banning single-use plastics, and ocean cleanup technologies.

Why is it difficult to clean plastic already in the ocean?

Plastic spreads across huge areas, sinks to deep water, breaks into microplastics, and mixes with marine life.

Are humans doomed because of plastic pollution?

No, but better stewardship and sustainable practices are needed to reduce the problem.

What are fisheries?

Industries and activities that harvest fish and other seafood from oceans, rivers, and lakes.

What is included when we talk about fisheries?

Fish, shellfish, marine organisms, and the industries that catch, process, and sell them.

How important are fisheries to the global economy?

They provide food, jobs, and income for millions of people worldwide.

What percent of ocean fisheries occur in the open ocean?

Only a small percentage occur in the open ocean.

Where are most fisheries located?

Along continental shelves and coastal regions.

What controls where fisheries occur?

Availability of nutrients, sunlight, primary productivity, and ocean circulation patterns.

What is the photic zone?

The upper layer of the ocean where sunlight penetrates and photosynthesis can occur.

Why is the photic zone important?

It supports phytoplankton growth, which forms the base of the marine food web.

What makes up the base of most ocean food webs?

Phytoplankton.

What is needed for photosynthesis and phytoplankton growth?

Sunlight, nutrients, carbon dioxide, and suitable water conditions.

What controls the amount of sunlight at different locations on Earth?

Latitude, season, and the angle of the sun.

What controls nutrient availability in the ocean?

Ocean circulation, upwelling, river input, and mixing of deep water

Where do ocean nutrients come from?

Deep ocean waters, decomposition of organisms, and runoff from land.

What is a thermocline?

A layer in the ocean where temperature changes rapidly with depth.

What role does the thermocline play in nutrient availability?

It can block nutrient-rich deep water from mixing with surface waters.

What causes a thermocline to form?

Solar heating of surface water and limited mixing with deeper colder water.

What is upwelling?

The movement of deep, cold, nutrient-rich water to the ocean surface.

How is upwelling forced?

Wind patterns that push surface water away from the coast.

What wind direction favors upwelling along a coastline?

Winds that move surface water away from the coast, allowing deep water to rise.

What are the patterns of primary productivity in the open ocean?

High latitudes, temperate latitudes, and tropical latitudes each have different productivity levels.

Why do high latitudes have strong seasonal productivity?

Large seasonal changes in sunlight and nutrient availability.

Why do temperate regions have spring and fall blooms?

Mixing increases nutrients and sunlight levels become favorable for phytoplankton growth.

Why are tropical regions less productive despite high sunlight?

Strong thermoclines prevent nutrients from reaching surface waters.

What controls phytoplankton biomass patterns over the year?

The interaction between sunlight availability and nutrient supply.

What happens to biomass when sunlight is high but nutrients are low?

Phytoplankton growth becomes limited.

What happens when both sunlight and nutrients are high?

Large phytoplankton blooms occur.