LiMPETS Field Blog

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… More

The LiMPETS Experience

by Emily Gottlieb, LiMPETS Coordinator for Central CaliforniaEmily

How does a sea anemone eat? What time of year are the most pacific mole crabs found on the beach? How do you tell the difference between flattened and slender rockweed? These are not questions from last night’s Jeopardy episode or this year’s AP biology test. These are questions that real students ask while they collect real data in the field as part of LiMPETS (Long-term Monitoring Program and Experiential Training for Students). For over ten years, LiMPETS has encouraged scientific inquiry through hands-on science experience, a theme that now beats throughout the NGSS (Next Generation Science Standards).

The Pacific Grove Museum of Natural History has coordinated LiMPETS for the California Central Coast (Davenport to San Simeon) since 2011 as part of the larger LiMPETS network. The network engages approximately 5,500 students and teachers annually monitoring sites from the Sonoma Coast to Los Angeles.

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Finding Meaningful and Lasting Connections with Our Local Marine Ecosystem

Author: Melea of the Branson School

The wind tickled our noses as we scaled down the steep trail to Duxbury Reef in Bolinas, CA for a monitoring of the rocky intertidal. Thrice a year, our Sustainable Seas club, which participates in the LiMPETS program, monitors Duxbury Reef, which we have adopted asimage3 our monitoring site since 2000. Peers from the Branson School enthusiastically shared anecdotes of past monitorings, marveling at the striking stripes of Anthopleura sola, also known as sunburst anemones, colorful, alien-looking nudibranchs, or stunning magenta sunsets they had witnessed. Scarcely anyone was on their phones (a rare occurrence for teenagers), and people seemed almost giddy to be outside and immersed in the cool, salty ocean air.

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Little Worlds: a day in the life of Sustainable Seas

Authors: Gaby and Jane

You are cruising along Sir Francis Drake Boulevard in a jam-packed suburban, each kid wrapped in infinite layers (of sweaters, hats, gloves, booties, and many many puffy jackets), snacking on homemade brownies, and bellowing the lyrics to one of the many archaic playlists found on old scratched-up CDs. Time flies as the car swerves around corner after corner, speeding through densely wooded forests, dry grasslands, quaint towns, and mountainous landscapes. And then just like that, you’ve arrived!

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Protecting the Sexy Areas of the Beach

Students collecting data on sand crabs

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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