Honors Marine Biology

Continental Shelf Communities

Module 12

February 21, 2013

Class Challenge

Class Quiz

Module 11 Coral Reef

Question 1

What are the three physical requirements for coral growth?

Corals need:

warm water, a hard substratesunlight … in order to grow.

Question 2

Identify these creatures as Reef Builders or Reef inhabitants:

Soft coral: Reef Inhabitant – does not form calcium carbonate exoskeleton.

Hard coral: Reef builder

Coralline Algae: Reef builder

Coral Grouper: Reef Inhabitant

Crabs: Reef Inhabitant

Question 3

Define and Draw:

Fringing Reef: A type of coral reef that forms as a border along the coast.

Barrier Reef

Barrier Reef: A type of coral reef that occurs at a distance from the coast

Atoll Reef

• Atoll: A ring of coral reef with a steep outer slopes, enclosing a shallow lagoon.

Question 4

A. TentaclesB. MouthC. SeptaD. ColumellaE. NematocystsF. CoenosarcG. Gut CavityH. Corallite

Field Trips

We have had 3 official field trips so far this year. We will have one more that is scheduled on April 20.

Fishing tournament held at Harts Landing

10:00am to 12:00 noon.

Continental Shelf Communities

The continental shelf is a gently sloping area, beginning at a point near land, just below the low-tide mark.

It continues out to the shelf break, which is the outer edge of the continental shelf.

Ocean Basins (Part 1): Features of the Ocean Floor (Continental Margin)

http://youtu.be/8Xpflh1187M

Virtual Field Trip: Underwater flyby of Southern California's offshore sea floor

http://youtu.be/kTTEajWRg4Y

This area contains abundant quantities of life. Vast fishing areas are found here.

Coral Reef communities are located on the continental shelf.

Let’s look at life on the bottom of the continental shelf.

Using scuba diving equipment and underwater submersibles, scientists are beginning to learn more about the vast resources in this area.

Oil and mineral deposits are found here, and nations depend upon many of the resources in this underwater zone.

Temperature

One of the most important physical factors in this community is temperature.

Continental shelf temperatures vary dramatically throughout the world. In warmer areas near the equator, there are many more species of organisms living on the continental shelf as compared to colder shelf areas near the poles.

The Polar Regions

Even though there are not as many species living on the continental shelves near the poles, there are some interesting organisms living there.

Sponges, seaweeds and invertebrates.

Based upon where these organisms live, they can be divided

into three groups:

1. Benthos: Marine Organisms that live on the sea bottom.

2. Nekton: Marine organisms that swim strongly enough to move against the ocean current.

3. Plankton: Marine organisms that cannot swim strongly enough to move against the ocean current.

Benthos

Organisms live on the bottom surface of the continental shelf.

Nekton and Plankton

Live in the water column above the continental shelf.

The main difference between plankton and nekton is that Nektonic organisms have the ability to swim against the direction of the current while Planktonic organisms cannot.

Subtidal

The continental shelf area is subtidal. That means that it stays underwater regardless of the tides.

It is still affected by the currents and waves. As the tides move in and out, strong tidal currents can move across the region. This keeps the water above the shelf well mixed resulting in:

1. a rich supply of nutrients, 2. relatively constant salinity and 3. temperature throughout the shelf from surface

to bottom.

Continental Shelf – Subtidal Community

Tidal currents spread nutrients that flow from nutrient rich rivers and estuaries into the continental shelf. This provides more available food for organisms that live here.

Scientists interchange the name of this area with subtidal communities.

Soft-Bottom Shelf Communities

Continental Shelf communities can be divided into two groups based upon the substrate of the ocean floor.

1. Soft-bottom shelf communities

2. Hard-bottom shelf communities

The type of substrate determines what types of organisms can populate the ocean floor.

Most are made up of soft sediments such as sand and mud. These soft bottom subtidal areas are frequently flat and are often similar in appearance to the muddy bottomed estuaries that we studied.

Infauna

Are organisms buried in the sediment and these make up much of the life here.

They are not quickly observed but are a major part of the ecosystem.

They feed on Detritus ie: burrowing tube worms, sand dollars, sea cucumbers, heart urchins and ghost shrimps.

These deposit feeders eat detritus in one of two ways:

1. They collect the detritus with tentacles

2. They swallow the sediments and then their digestive systems sort the detritus from the sediments. The detritus is used and the sediments are excreted. Just like earthworms.

Figure 12.2

Suspension-Feeding Infauna in a Sandy Substrate page 291

Epifauna

Are the larger creatures that can be easily seen. Flounder and rays live on the surface of the sandy and muddy bottoms.

Seaweeds are often part of the epifauna, but only if they find a hard substrate to attach to.

Rocks, Shells are often covered with algae growing on it.

Queen conch shell covered with algae growth.

So you see there can be soft bottom Environments that are unvegetated as well as Vegetated.

Meiofauna

Can only be seen through a microscope. These tiny organisms dwell in between the sediment particles.

They either attach to individual bits of sediment or move freely between them.

Protozoans, nematodes, small worms and crustaceans.

Only protozoans are single celled organisms.

Sea grass communities are usually associated with estuaries, but they are also found in soft-bottomed shelf communities. And are usually found in relatively shallow and sheltered from extreme currents and wave action.

Turtle grass is most commonly found in the tropics and eelgrass is in temperate areas.

Figure 12.6

Sessile organisms inhabiting seagrass

Page 294

Soft-bottom Subtidal Communities

Have a larger number of species living in them compared to soft-bottom estuaries.

Physical conditions do not change as drastically as they do in estuaries.

Continental Shelf Communities

1. Soft-Bottomed Shelf Communities

a. Unvegetated

b. Vegetated

2. Coral reefs

3. Hard-Bottomed Shelf Communities

Hard-Bottom Shelf Communities

These are not as prevalent as soft-bottomed communities.

They are prominent in some locations near Anarctica.

Hard-Bottom Subtidal Communities

There are two major categories:

1. Rocky Bottomed Communities

2. Kelp Beds

The Atlantic Shelfbreak: Using robotic vehicles to observe ocean life

http://youtu.be/v0OYJzyxAZc

Swimming Through a Natural Aquarium

http://youtu.be/qngZBYHlznQ

Lab: Subtidal Zone Predator-Prey Relationships

February 21, 2013

Turtle-> Pen shell->phytoplanktonTurtle->stingray->shrimp->zooplankton or phytoplankton->photosyntheticdetritusKiller whale->Fish->plankton/zooplanktonCrab-> baby sea turtles->or starfish->coral->algae or planktonWhales-> or fish->Krill->planktonBaracuda ->mullet or herring->shrimp->zooplankton or phytoplanktonConch->Quahog shell->phytoplanktonShark->Mackerel->minnows->zooplanktonPolor bears->seals->fish->shrimp->zooplankton or phytoplanktonStingray-> starfish or sand dollar->algae or brain coral->planktonStarfish or Sheep head->Barnacles->zooplankton->phytoplankton

Observation of Epiphytes of Sea Grass in Subtidal Zone

February 21, 2013To observe the Sessile organisms inhabiting Sea

Grass using a microscope.

Observations:Spirobis – calcified worm shellAmphipod (sand fleas)Sea SquirtsJuvenile Fish

Homework

Take Module 11 test

Read Module 12 to page 297

OYO: 12.1 – 12.9

Study guide: define a-c questions 2-18

Quiz:

Class challenge:

• http://quizlet.com/776732/exploring-creation-with-marine-biology-module-12-continental-shelf-communities-flash-cards/