Oil? Spills? and Crabs? Oh my!

Sarah, Anika, and Marco
Bishop O’Dowd High School

How did the 2007 oil spill in the San Francisco bay affect the population of sand crabs in the area? This question is important because sand crabs are significant to beach ecosystems; they are food for many animals, and they are also an indicator species. This means that scientists and researchers can look at sand crabs to determine the health and sustainability of beaches and other marine ecosystems.

Source: https://nrm.dfg.ca.gov

Source: https://nrm.dfg.ca.gov

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Crabtivating Sand Crab Distribution at Playa Del Rey Beach

Cleo, Jerome, Kate, and Gloria
Bishop O’Dowd High School

No need to feel clawstrophobic (or get crabby), there is plenty of room for all the sand crabs on Playa del Rey Beach! So, how has sand crab population changed over time on this Southern Californian beach? This question allows us to further understand the Southern California sand crab population.
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What about the Children?

Sand crabbingGianna, Jack, Peter, and Nathan
Bishop O’Dowd High School

After going on a trip to Ocean Beach in San Francisco and gathering data about the local sand crabs, we wondered how many of them were “recruits,” little crabs which are new to life on the beach. How does this number change over time? Once a recruit settles on a beach, it will spend the rest of its life there. So, a healthy recruit population means that there will be a healthy adult population in the future (unless there is an environmental hazard). As long as there are no environmental hazards or strange weather conditions, the portion of recruits can be used to predict future sand crab growth and decline.
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Battle for the Beach-Crustacean Nation

by Miles, Sophia, and Charlie
Bishop O’Dowd High School

A sharp, cold wind rips across the beach, chilling the shivering O’Dowd students to the core. But there is no room for weakness. The research must be conducted at any cost. As the oceans continue to be examined, the relationship between sand crabs and sanderlings remains unclear. The two species are locked in the age-old, evolutionary battle of predator and prey, but the other aspects of their interactions are unknown. Exploring the correlation between the abundance of sand crabs and the abundance of shorebirds on Ocean Beach is a key component of understanding the beach as a whole. This research is vastly important, as sand crabs act as prey for many species on the sandy beaches, and serve as an indicator species, or a species that serves as a gauge for a habitat’s health.
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Itch for Crabs? (Not those crabs!)

Mole crabby Brian, Somari, and Charles
Bishop O’Dowd High School

Have you ever looked down while at the beach, and seen tiny creatures rolling around, and live in the sand? These tiny creatures are called sand crabs and they are quite paramount to their ecosystem. You may be wondering why sand crabs are so important and it is because they are prey for many animals such as shorebirds and fish. As a species, they can determine whether or not the ecosystem will be healthy. sand crabs make up 80-90% of the intertidal invertebrate biomass. Males and females vary in sizes but the females tend to be larger.
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Little Crabs in a Big Storm

Sand crab in sandby Julia, Olivia, and Thomas
Bishop O’Dowd High School

Emerita analoga, or the common Pacific sand crab, is an small animal with a colossal impact on beach ecosystems. We will examine the population trend in sand crabs over time at ocean beach, and examine
possible environmental factors that could have caused this, specifically El Nino. The sand crab is an indicator species, so examining the health of their population will allow us to examine the health of the sandy beach ecosystem as a whole.

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Sand Crabs? That’s so Raven.

Julian, Lucas, and Lily
Bishop O’Dowd High School

Sand crabs are herbivores and an important food source for other beach organisms, specifically shorebirds. We assumed that if the sand crab population is thriving on a beach, then the shorebird population should be doing well too. We looked at data of sand crabs and shorebirds along the north-central California coast over the course of a year. Our original hypothesis was that if the population of sand crabs was high, then naturally the population of shorebirds would also be high. But, contrary to our hypothesis, a flourishing sand crab population means there are less shorebirds… Continue reading

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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