Protecting the Sexy Areas of the Beach

Authors: Katy & Sarah

Students collecting data on sand crabsDo you know where sand crabs find love? Is there such a thing as a Match.com for sand crabs? It just so happens that there’s a great spot for sand crab love, and it’s along certain parts of Ocean Beach.

Ocean Beach isn’t only a great spot for sand crabs to find love, but it’s also a near many new Marine Protected Areas in California. The National Oceanic Administration Association informs us that California has established 120 new Marine Protected Areas  (MPAs) that create safe environments for marine animals. MPAs  conserve the nation’s cultural and natural resources and there are currently 437 MPAs in the United States. We wanted to study sand crabs on Ocean Beach so we could learn more about sand crabs and where they are most populated.

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Sticky Situation: How did the Cosco Busan Oil Spill Affect Sand Crabs?

Authors: April, Tess & Emily

OilSpillIn November of 2007, the container ship, Cosco Busan collided with a Bay Bridge support tower. The ship was fatally wounded, oozing 53,569 gallons of oil into the San Francisco Bay. The aftermath of this incident may have accounted for a steep drop in the sand crab population on San Francisco’s Ocean Beach in the years to follow. The oil spill may have affected the number of surviving recruits, or young sand crabs, especially since the mating season for sand crabs occurs in spring and summer, thereby affecting the number of recruits in 2008.

Our Marine Biology class participated in the LiMPETS sandy beach monitoring program on September 20th, 2014 at Ocean Beach. To survey the sand crabs living on the beach, we took 50 random samples of sand from the swash zone, or the zone of wave action. In each of these 50 samples, we observed any sand crabs that were found. We recorded their gender and assessed whether they were a recruit  (young crab) or adult.

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Does Upwelling Really Raise Populations of Marine life?

Authors: Francesca & Jordan

There are four seasons that we all know and love; summer, a time for swimming and tanning; fall, a beautiful season with pumpkin flavored everything; winter, the time to ski; and spring, when the winter thaws.  However, many of us may not be familiar with the seasons of the ocean. These three ocean seasons are known as winter storms, upwelling, and relaxation. These seasons affect the ocean’s inhabitants much like ours affect us.  One of the smaller residents of the sea that seem to be affected by these seasons is the sand crab (Emerita analoga).

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Could Climbing Climate Cause a Copious Amount of Sand Crabs?

ClimateClimbingAuthors: Gabrielle, George & Viviana

The California coast has well established populations of sand crabs. However, sand crab populations in Oregon occur only occasionally, and seem to be replenished by those along the California coast. The Davidson current, which runs along the western coast of the United States, carries crabs from California up to Oregon. These populations thrive during a strong El Niño period, which is a period characterized by unusually warm water in the tropical Pacific and decreased upwelling along the coast of California in the summer months. Increases in water temperatures caused by El Niño have led to shifts in the distribution of many marine species northward along the California and Oregon coastlines.

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Small Things Can Make Big Impacts

Authors: Simone & Andrea

In general, human activities can positively and negatively influence the environment in which organisms inhabit. Every organism on this earth plays an important role in maintaining the balance of life no matter the size. Scientists may research the study of life on a small scale in order for us to better understand how small organisms can influence the environment in big ways. If in a community a small factor is harmed there might be consequences for those who heavily depend on it.

Our marine biology class participated in the LiMPETS sandy beach monitoring program on September 20th, 2014 at Ocean Beach located in San Francisco. We took 50 cores from the beach and recorded how many sand crabs were found per core. We did this so we could analyze and compare the sand crab population in the 11 years that data were collected. This is necessary in order to have a complete picture of any changes in the population.

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Beyoncé’s Hit Single: Female Sand Crabs Run the World

Authors: Amanda, Anne & Hannah

Female Sand Crab with EggsAccording to Beyonce, girls run the world, but from Bishop O’Dowd’s sandy beach monitoring data, it’s female sand crabs with eggs the run Ocean Beach. Sand crabs are important animals on California beaches because they can indicate the health of the area of the beach in which they live. Also, they are an important species in the food chain. They are the primary consumers on the beach and many other species rely on their existence.

Over the past ten years, the amount of female crabs with eggs has fluctuated greatly. The crabs had fruitful mating seasons in 2009 and 2011, as shown by the graph below. Following the pinnacle of pregnant crab abundance in 2009, Ocean Beach’s sand crab population boomed (see year 2010 in the graph). Most of these crabs were juveniles and possibly offspring of the pregnant females from the year before. This population boom may be due to climate change; recent studies have shown our planet faces challenges that may be devastating for the species that make their home, reproduce, and live in sandy beaches.

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Mole Crabs and Beaches: Could We Affect Them?

Authors: Halie, Jolene & Matt

Sand Crab Measuring

Everybody loves going to a nice sandy beach. We set out to learn more about the health of beaches by analyzing the abundance of mole crabs at beaches near cities and beaches in more remote areas.

Although they are no bigger than the size of your thumb and seemingly unimportant creatures, mole crabs are very significant animals on sandy beaches. Their numbers are also indicative of the general health of the entire beach because they are in the middle of the food chain. This means that they are affected by both a scarcity in their prey or predators.

So, how do mole crab populations vary from urban beaches to remote beaches?

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