Ch. 13 Estuaries

What is the main difference between a bay and an estuary?

Bays are coastal ocean areas partly enclosed by land, while estuaries have lower salinity due to freshwater inflow.

Why do bays and estuaries experience more rapid temperature variations than the open ocean?

Due to proximity to land and hot or cold winds from the continents.

Which U.S. coast is more estuarine?

The Atlantic coast (80-90% estuarine).

What are the four types of estuary formation?

Fjords, drowned river valleys, tectonic estuaries, and lagoons

How are fjords formed?

By glacial cutting.

Which type of estuary is San Francisco Bay?

A tectonic estuary

What are the four classifications of estuaries based on salinity?

Well-mixed, weakly stratified, strongly stratified, and salt wedge

Which type of estuary has very high runoff and a narrow discharge channel?

Salt wedge estuary.

What happens when a sill is present in an estuary?

Ocean inflow is restricted, and most water exchange occurs above sill depth.

What is anti-estuarine circulation?

A circulation pattern where evaporation exceeds precipitation, increasing salinity

Why do estuary organisms need to be highly adaptable?

They must tolerate fluctuating salinity and temperature.

Why is primary productivity high in estuaries?

Due to nutrient input from river-borne materials.

What is flushing time in an estuary?

The time it takes for water (and pollutants) to be replaced or flushed out.

Why are long flushing times harmful to estuaries?

Pollutants accumulate, increasing environmental damage.

What factors affect flushing time?

Estuary volume and outflow rate.

Name three types of pollutants commonly affecting estuaries.

Sewage, fertilizers, and plastics.

What negative effects does sewage have on estuaries?

High oxygen demand, burial of benthos, and viral contamination of shellfish.

What is eutrophication, and how is it caused?

Excessive algae growth caused by nutrient runoff, leading to oxygen depletion

How does flood control affect estuaries?

It decreases sediment deposition and may lead to coastal flooding.

Why is the destruction of wetlands harmful?

It destroys habitats and endangers plant and animal species.

What is the risk of introducing non-indigenous species?

They may outcompete or prey on native species.

Name three invasive species threatening estuaries and coastal zones.

Zebra mussels, European green crab, and sea lamprey.

What is the main factor determining how harmful pollution is to an estuary?

The flushing time.

How do human activities increase estuarine pollution?

Through sewage discharge, oil spills, and introduction of invasive species.