| Where
did we go? On June 16th, we drove to Redwood Creek Harbor in Redwood City to board the Robert E Brownlee, the research vessel of the Marine Science Institute. |
Brenda drew a scene of Redwood Creek harbor. |
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| What
did we do? The Robert E Brownlee is a 70-foot research vessel that was specially designed to help people learn about San Francisco Bay. We used nets to catch fish and plankton and learned to use identification guides to identify them. We viewed the live plankton through a microscope. |
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| One of the most exciting parts of the day was seeing and touching baby leopard sharks and sting rays that we caught in nets. The students were surprised to learn that the skin on the sharks and rays was rough like sandpaper. |
Susan is passing around the bat ray that we caught in a net and placed into a touch tank. Susan carefully holds the tail so that it won’t whip around. |
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| We also touched the leopard sharks and sting rays that we found in our nets. To investigate the mud from the bottom of the bay, we used a heavy scooping tool called a Peterson device. It took three attempts to obtain a good sample but we finally pulled up a nice big pile of mud. Even though we are in the middle of the bay, its only a about 12 feet deep. | ||
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We dumped the mud onto sieves to look for benthic (bottom-dwelling) organisms, such as worms. | |
Believe or not, the average depth of the San Francisco Bay is only 12 feet. Captain Jackson, the skipper of the Robert E Brownlee, said that in 1850 the average depth of the Bay was 43 feet. That’s right. Over the last 150 years the bottom of the bay has risen 31 feet! Where did all this sediment come from? Most of the mud in the San Francisco Bay comes from the Sierra Nevada mountains. During the Gold Rush, mining companies destroyed many mountainsides in their quest to find gold. They used high-pressure water to blast away huge mountains. Over the years all the sediment loosened by hydraulic mining has gradually washed into the Sacramento river. This had led to the deposition of tons of sediment in the San Francisco Bay. |
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| Have you ever touched a shark or a ray? Although these fish look different at first glance, they are actually similar in many ways. They both have leathery skin that feels like sandpaper. Sharks and rays, unlike bony, have skeletons made of cartilage. Touch your nose and ears—they are also made of flexible cartilage. |
Erech looks at a young leopard shark. |
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| Let's
Go! Visit the Marine Science Institute website: http://www.sfbaymsi.org/ |
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