Marine Bio chapter 13

What is the continental shelf?

The submerged edge of a continental plate extending from the low tide line to the shelf break.

How does the slope of the continental shelf compare to the slope past the shelf break?

The slope of the continental shelf is normally more gradual, while the slope past the shelf break is normally very steep.

What is the average depth of water at the shelf break?

Around 490 feet.

What is the average width of the continental shelf?

48 miles, with variations from 0.6 miles to 470 miles.

Why is the continental shelf biologically significant?

It is the richest part of the ocean, hosting more species and potential natural resources like oil and natural gas.

What agreement did the United Nations reach in the 1950s regarding marine resources?

Each country shall have control over marine resources out to 200 nautical miles off their coast.

What types of organisms are commonly found on the continental shelf?

Sponges, cnidarians, worms, molluscs, fish, and echinoderms.

How does water temperature over the continental shelf compare to deep sea water?

It varies more than in the deep sea but less than in estuaries due to shallower depths and mixing from waves and currents.

What factors contribute to nutrient availability in the continental shelf waters?

Water turbulence from waves and currents keeps nutrients mixed and available to organisms.

What are bioturbators?

Organisms that disturb bottom sediments, helping to oxygenate benthic soils.

What types of communities exist on the continental shelf?

Soft-bottomed benthic, seagrass beds, kelp forests, and hard-bottomed benthic.

What is the dominant bottom type on the continental shelf?

Soft-bottomed benthic.

What role do larvae play in soft-bottomed benthic communities?

Larvae are attracted to areas where adults reside, likely due to chemical cues in the water.

What are seagrass beds, and where are they best developed?

Seagrass beds are underwater plant communities best developed in sheltered, shallow waters with good clarity.

What is Thalassia, and why is it significant?

Thalassia, or turtle grass, is a common seagrass consumed by green sea turtles, which may farm it for better growth.

What is Zostera, and where is it commonly found?

Zostera, or eelgrass, prefers cooler waters and is mainly found in the Pacific and North Atlantic.

What characterizes hard-bottomed subtidal communities?

They often result from submerged rocky shorelines and attract a variety of organisms, including sessile types.

What are kelps, and what conditions do they require?

Kelps are brown algae that require cold waters and are nutrient-needy due to their fast growth.

What is Laminaria, and where is it found?

Laminaria is a smaller species of kelp found in the North Atlantic and Pacific, known for rapid growth.

What is Macrocystis, and why is it important?

Macrocystis is a large kelp species that can grow over 100 feet and forms thick forests, serving as a major ocean ecosystem.

Who are the primary consumers of kelp?

Sea urchins are the largest direct consumers of kelp.

What is the significance of kelp forests in marine ecosystems?

Kelp forests provide habitat and food for thousands of organisms.

What is the role of nutrients from estuaries and terrestrial ecosystems in the continental shelf?

They contribute to the nutrient-rich waters that support diverse marine life.

What are meiofauna?

Small organisms that live in the spaces between sediment particles, many of which are unique to these environments.

What types of feeders are common in soft-bottomed benthic communities?

Deposit feeders that get nutrients from sediment and suspension feeders that filter nutrients from the water.