Posted by: cassandrabrooks | October 10, 2012

California Sea Otters: A gap in the Point Reyes ecosystem

Photo by Joe Robertson/Wikimedia

Sea otters once thrived off the entire west coast of North America. The kelp forests off of Point Reyes Seashore would have been prime otter habitat. But aside from the occasional wayward male, visitors at Point Reyes won’t see California sea otters today. They were hunted to the brink of extinction in the 18th and 19th centuries for their thick pelts. A small population has recovered off the coast of central California, yet they have failed to expand their range. But why? Join me as I talk to otter experts about the status of their populations and why Sea Otters have failed to expand their range throughout California. Video produced by Cassandra Brooks,Pacific Coast Science and Learning Center at Point Reyes National Seashore.

Watch the video, here.

Posted by: cassandrabrooks | September 6, 2012

Declining fog in coastal California?

California fog. Photo by John B Weller.

The rich, lush environment of Point Reyes, and really all of coastal California, heavily depends on the fog. During rainless summers, this fog, which can account for 1/3 of the ecosystem’s water input, is critical to the persistence of the local plants and ecosystem. But recent studies have indicated that the fog is declining from the California coast. Join me as I talk to Bay Area experts, including Todd Dawson at UC Berkeley and Mike Vasey of SFSU, to find out more. Video features beautiful time-lapse photography of fog by John B Weller. Video produced by Cassandra Brooks, Pacific Coast Science and Learning Center at Point Reyes National Seashore.

Watch the video, here.

Posted by: cassandrabrooks | February 15, 2012

Searching for the endangered Black Abalone

Black Abalone, one of seven abalone species found in California’s intertidal waters, have gotten sick, really sick with withering syndrome. This disease, along with overharvesting, has caused Abalone populations to plummet, landing them a spot on the endangered species list.

Thus far, Southern California populations have been especially hard hit by withering syndrome. Yet little is known about the status of Northern populations. Join me as I talk with Darren Fong, Aquatic Ecologist with Golden Gate National Recreation Area, and former interns Amy Henry and Kari Eckdahl as they look for Black Abalones throughout Northern California. (video produced by Cassandra Brooks, Pacific Coast Science and Learning Center, interviews by Charles Briscoe)

Watch the video on youtube here.

Posted by: pointreyesscience | December 12, 2011

Batillaria Blog

Batillaria in a growth experiment

It’s true that few people care to get intimate with the muck at the bottom of Tomales Bay, but as for myself, I could not wait to spend my summer face to face with it. My interests in marine invasion ecology lead me to the Bodega Marine Lab where I was offered the opportunity to play in the mud for four months. I was thrilled at the prospect of getting up close and personal with the invasive Japanese mudsnail, Batillaria attramentaria. With bucket and sieve in hand I slogged forward, rain or shine, battling the Batillaria. Formally my job description entailed surveying the new population in Bodega Harbor and testing eradication methods on existing populations in Tomales Bay. In addition to this I also spent a lot of time researching and field-testing my own questions pertaining to the parasites that live within the snails. I was interested in observing infected and uninfected snail behavior.

My first trip to Tomales Bay was at Walker Creek. Before I even got the chance to sink my shoes into the mud, I could see shells littering the surface I was about to step on. Little did I know a small patch of mud could contain well over 1000 snails! I was soon to discover how quickly these snails are able to take over, inhabiting nearly every nook and cranny of the shoreline. In Tomales Bay Batillaria can be found living in brackish streams (a mix of fresh and salt water), salt marsh pannes, cobbled shores and on the expansive open mudflat. The snails inhabit the shoreline at varying densities from Walker Creek to Millerton on the eastern side of Tomales Bay, and from Indian Beach on the northwest side down to Inverness.

How did they get here?

In the 1930’s when the Pacific Oyster from Japan (Crassostrea gigas) became desirable for aquaculture on the west coast, Batillaria among other mudflat species from Japan arrived in the mud attached to the oyster shells. Batillaria ranges from Elkhorn Slough, California, all the way to Boundary Bay, British Columbia (Hanna 1966) at sites where Pacific oyster aquaculture was prevalent (Byers, J.E. 1999). Within the past 5-10 years however, Batillaria has spread to places where Crassostrea gigas has not been introduced. Heidi Weiskel from UC Davis and her research team found a new population in 2005 in San Francisco Bay and 2007 in Bodega Harbor. Using her research grant from the NPS, she started working on comparative studies, focusing on Tomales Bay as a critical reference population for the new populations.

A little natural history…

The snails graze along the mudflats like small herds of cattle, feasting on diatoms, or other photosynthesizing microalgae that cover the mud’s surface. Powered by an herbivorous diet, these snails can grow to sizes reaching 45mm. When new recruits emerge they are only visible to the snail-trained eye (less than a millimeter long!). When the snails reproduce their young develop directly from an egg as opposed to having a planktonic, or swimming stage. The direct development does play a role in limiting the species spread.

Tiny invader, big impacts

 Before Batillaria established its domain, the native California mud snail Cerithidea californica prevailed in Tomales Bay. After its introduction the snails were seen to coexist on the mudflat (Whitlatch & Obrebski 1980). Since then, the non-native has successfully taken over the flats of Tomales. Not only have these snails caused local extinctions of an ecologically similar species (Byers 2000), they have introduced a non-native parasite that has the potential to alter the mudflat community and possibly other levels of the food chain (Lafferty & Kuris 2009). The snails also cause a variety of habitat changes including an increase in hard substratum, as well as potential alterations to microalgal biomass (due to feeding habits) and competition with the infaunal community. The hard substrate created by their shells in some cases facilitates the invasion of other organisms, both native and non-native (Wonham et al. 2005) and may also affect shorebird foraging of what was once soft sediment.

Brightly marked Batillaria were used as part of a mark-recapture study

The spring months mark the re-appearance of the snails at Bodega Harbor. In the late fall the snails go under the mud and then reappear around May, a phenomenon unique to the new population found at Doran Beach (the snails at Tomales Bay are so abundant that they can be seen on the mudflat all year round). In the beginning of May, population surveys are carried out utilizing the same sampling protocol from year to year to maintain continuity. Methods include running a transect tape across the populated area and measuring vertical transects at random intervals. Sampling is done along the vertical transects, which entails sinking the sawed off top of a 5-gallon bucket into the mud and scooping up the surface with your hands. The sample is sieved (using a 2mm mesh) and the snails are put into a bag to be counted, sized and dissected in the lab. After the snails are dealt with in the lab all of our samples are put in the freezer for at least 24 hours and then disposed of using the designated protocol for marine invasive species.

The above population survey was conducted in Tomales Bay in 2008, providing a wealth of information concerning the established population, which was used to compare to the two new populations in San Francisco Bay and Bodega Harbor.  In May of 2010, Heidi Weiskel and I conducted the survey in Bodega Harbor at Doran Beach where the relatively new population exists. The population survey enables us to track its rate of spread, distribution and demographic characteristics. Information regarding sex, size and infection rate can be accounted for. In particular, the snails at Bodega Harbor provide a unique opportunity to test predictions concerning founder populations (for example, how quickly they spread, what their distribution patterns are, and how their size class structure changes over time).


Prior to the 2010 field season, teams of volunteers handpicked and sieved for snails at Doran Beach, removing more than 10,000 pounds of snails! Because the population at Doran Beach is still relatively small, there’s a push to test different eradication methods in order to control the spread.

Funded by the California Sea Grant, a team of scientists from the Bodega Marine Lab spent the 2010 field season testing a device dubbed –“The Super Sucker”. This low-tech machine includes a gas-powered motor attached to a 5-gallon pail, complete with sieve, intake hose and bike break throttle. Two trial experiments were run, one at Doran Beach (low density <10 snails/m2) in Bodega Harbor and one at Walker Creek (high density >1000 snails/m2) in Tomales Bay. The experiments compared handpicking versus the “Super Sucker”, running methods of eradication simultaneously.  We hypothesized, as most would, that anything would be faster than tediously picking up snails by hand. We also thought that the Super Sucker would be able to pick up tinier snails that a hand-picker may not see.

During the trials the Super Sucker performed well, picking up small and large snails (3mm and bigger) with little sediment. However, technical glitches and difficulty while maneuvering the machine during the trails slowed its efficiency. Not until we conducted the trials in a more uniform density (Walker Creek) did comparisons between the two methods become clear. In a 10 minute time period it seemed that I was able to clear a 2m x 1m patch handpicking as fast as the Super Sucker could. However, not until we took our samples to the lab were we able to conclude that in both low and high density areas, handpicking was at par or slightly MORE efficient than the “Super Sucker” at eradicating snails. Also the frequency of smaller sized snails (5-10mm) being eradicated was the same across both methods. When comparing the Super Sucker across densities, it seemed to be much more effective in high density areas and on flat muddy surfaces as opposed to coarser surfaces that contain many pebbles or sand that are vacuumed up along with the snails and can clog the hose and sieve

The "Super Sucker" was used to remove the invasive snails

Moving forward…

The small engine was the biggest constraint controlling the Super Sucker’s efficiency. Sucking up water and mud was a huge strain on the motor requiring more fuel than anticipated. Maneuverability was also a challenge on the mudflat. Dragging equipment on a plastic sled through varying terrain (marsh, stream, mud and stones) was difficult and frustrating at times! Without further modification and a more powerful motor the device will not achieve higher efficiency than hand picking. Testing the Super Sucker proved to be a valuable exercise as now time and funds can be re-directed toward other methods of eradication such as molluscicides, heating and raking.

It’s likely that humans moving between infected and uninfected areas carried the snails to different locations creating the new populations. Therefore, it’s imperative that we inform ourselves about what species belong where and to act accordingly, especially when non-native and invasive species are concerned. It’s critical to keep this in mind when we are in Tomales Bay, whether we are kayaking, exploring or researching. Always be sure to thoroughly clean off gear, equipment and boots before entering another water body. We all need to work together to stop the spread!

For more information about Batillaria attramentaria in Tomales Bay you may contact Heidi Weiskel at UC Davis (

Finally I’d like to thank the hardworking team of researchers who have contributed their time, support, sweat and tears- Chris Pollio, Christy Bowles, Ted Grosholz, and Heidi Weiskel.

Katie Houle


Byers, J. E. (1999). The distribution of an introduced mollusc and its role in the long-term demise of a native confamilial species. Biological Invasions 1(4): 339-353

Byers J.E. (2000) Competition between two estuarine snails: implications for invasions of exotic species. Ecology 81: 1225–1239

Hanna G.D. (1966) Introduced mollusks of Western North America. California Academy of Sciences Occasional Paper 48: 108

Lafferty K.D. and Kuris A.M. (2009) Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail. Philosophical Transactions of the Royal Society of Biology 364: 1659–1663

Whitlatch R.B. and Obrebski S. (1980) Feeding selectivity and coexistence in two deposit feeding gastropods. Marine Biology 58: 219–225

Wonham, M. J., O’Connor, M. & Harley, C.D.G. (2005) Positive effects of a dominant invader on introduced and native mudflat species. Maring Ecology Progress Series 289: 109–116

Posted by: cassandrabrooks | September 21, 2011

Burning Ancient Ocean Life

Marine Algae - the basis for 95% of our oil reserves (photo credit: Julie Kuo)

Phytoplankton form the base of the ocean’s food chains, transferring energy from the sun to sustain the global ocean. These tiny floating plants account for half of the photosynthetic activity on Earth. They also generate the majority of our fossil fuels…

Join me as a I talk with Ivano Aiello, Geological Oceanographer at Moss Landing Marine Labs, about how oil reserves take hundreds of millions of years to form. “Our rate of consumption is orders of magnitude faster than anything that has to do with the actual formation of oil,” Aiello says. “We are exploiting something that moves so slowly, there is no way that it can be regenerated anytime soon.”

Watch the audio slideshow here or on youtube here.

Posted by: cassandrabrooks | May 15, 2011

Ocean Acidification: Where will all the seashells go?

More than a hundred thousand marine species build their bodies using calcium carbonate, including snails, oysters, sea stars, coral, and plenty of planktonic animals. This incredible diversity of life evolved over millions of years, as animals figured out ways to pull calcium and carbonate ions from the water to build shells and skeletons so robust that they remain intact long after the animals perish. But all of this is changing. Our addiction to fossil fuels and the billions of tons of carbon dioxide we’re pumping into the atmosphere each year may be undoing millions of years of evolution in a geological blink of time.

Join me as I talk with ocean acidification experts about the uncertain future of our oceans.

To watch the audio slideshow on YouTube, click here.

To watch it on the new San Francisco Bay Area National Parks Science and Learning website, click here.

Posted by: cassandrabrooks | January 6, 2011

Deep-water Corals of Cordell Bank National Marine Sanctuary

Much of the ocean is a desert, dark depths devoid of life with muddy bottoms where animals scour for food and mates. But in the midst of these muddy bottoms, rocky banks rise from the continental shelf providing structure for life to grow and flourish. Cordell Bank, just 20 miles off the Point Reyes Seashore, is one such place.  A world bursting with creatures beyond our wildest imaginations.

Join me as I talk with Cordell Bank National Marine Sanctuary superintendent, Dan Howard, and research coordinator, Lisa Etherington, as we discuss the basis of the bank’s biological wonderland and the importance of protection, particularly in the face of climate change.

To watch the audio slideshow on YouTube, click here. To watch it on the new San Francisco Bay Area National Parks Science and Learning website click here.

Posted by: pointreyesscience | June 23, 2010

Intern Trip To Pinnacles

The three network science communications interns based out of Golden Gate National Recreation Area took a trip down to Pinnacles National Monument to participate in surveys and learn more about SFAN’s southernmost park unit.

Condor Monitoring

Upon reaching the saddle of the High Peaks trail we were greeted by a hopeful intern with the American Conservation Experience named Carmel de Bertau, but no actual condors. We decided to break for lunch and lay back on the rocks before helping with the survey – just for a few minutes rest after a long hike under the warm sun.

A California Condor soars overhead the High Peaks Trail in Pinnacles National Monument. Photo Credit: Mason Cummings, PRNSA

Eager to see my first condor, I arose to scan the expansive view from atop the High Peaks ridgeline – still nothing. Carmel assured me that our chances of a condor sighting were good, and pointed out a former nest site in one of the adjacent cliffs. Still, I was skeptical. One of the condor chicks from that particular site had recently been relocated to the Los Angeles Zoo after researchers discovered toxic levels of lead in his blood.  As scavengers, condors often feed on the remains of carcasses shot with lead bullets; it’s an all-too-common theme that has nearly driven the entire species to extinction.

“Well, this was a nice hike even in the absence of condors,” I began to tell myself. But at that moment something came soaring out from behind the rock pillars. “Is that a giant turkey vulture?” I thought, “or could it possibly be…”

“There’s one!” confirmed Carmel as the bird effortlessly cruised in circles above our heads. I began to relish in my very first condor sighting, and then four more suddenly appeared – all looping around directly overhead.  As we began to make out the ID tags we realized that some of the birds were from Ventana, and some from Pinnacles. “There’s got to be a carcass somewhere close.”

That’s when I noticed that my fellow intern was still resting from the hike, looking eerily like a carcass lain peacefully atop one of the rocks, and I couldn’t help but wonder…

-Mason Cummings

Bat Monitoring

Being able to walk through Bear Gulch Cave at this time of year is a rare treat. A few years back, a grad student researching bats discovered a bat population taking hold in the cave. Unfortunately, because of the cave’s unique, open nature and high visitation, growth of the bat population was hindered prompting the park superintended to close the cave for several years.  Although the park now opens the cave to visitors for part of the year, when we went we were able to get a unique, private view during bat season thanks to park biologist Paul Johnson.

Talus Caves such as this provide ideal habitat for many species of bats. Photo Credit: Mason Cummings, PRNSA

The cave is different than the more commonly known solution caves. Bear Gulch Cave is the result of massive boulders falling down onto each other and creating a series of enclosed rooms. As we ventured deeper into this random assortment of boulders it became time to turn on our headlamps and open our ears for the high-pitched screeches of the bats. Making our way up the stairs, we could not see an bats but it was very clear from sticky guano on the railings that the flying mammals had been in the area; it seems the deeper we went, the deeper the guano.

As the photographers on the team set up their equipment and waited for their long exposure times, I got the chance to crawl into a hidden room, off the trail, looking for bats with Paul. The space was tight, requiring me to get on my belly and inch across. The guano here was the thickest and we were not surprised to see a bat fly overhead. However, the colony was still to be found, so it was off into the deeper reaches of the cave. At one point we came across the creek again, this time it dropping off in a beautiful channeled waterfall. Although the fall as refreshing, inspiring, and relaxing, it reduced our ability to listen out for bats so we headed out further. It was in the next room that, while just wandering around, I found the bat colony. They were out of sight, but they could certainly be heard as they screeched and clicked from behind their hidden roost. The room was too tight to fit both us and the bats, so after a quick check of the monitoring devices, it was back out of the cave and into the openness of Pinnacles National Monument.

-T.J. Utset-Ward

Raptor Monitoring

At 7:00 AM the next day we set out behind Gavin Emmons onto the trails of Pinnacles National Monument.  Our mission was to monitor breeding raptors in the park, an effort that Gavin has lead for the past seven years.  The raptors’ success is an important indicator of the well-being of Pinnacles’ unique ecosystem, and knowing where they are during breeding season helps the park determine where and when to close trails and cliffs to hikers and climbers that might disturb them.

Juvenile prairie falcon. Photo Credit: Gavin Emmons, NPS

Soon we headed off the trails towards some chalky cliffs in the distance to check in on our first raptors of the day, four young prairie falcons. We easily spotted one with its dark brown plumage clearly visible against the lighter shades of the cliff, and then another not far from the first. As we scanned the cliff-face, one of the adults swooped in with a hunk of meat for one of the fledglings. We could hear other fledglings’ excited vocalizations, and continued hiking to get a different vantage point.  Sure enough, two smaller fledglings, probably males, came into view.  Having confirmed that all four of the nestlings had fledged, we headed to our next destination, a red-shouldered hawk nest.  Two large fledglings were present and accounted for high in a gray pine. Moving on, we came to a sharp-shinned hawk nest, where the female was still incubating her eggs and trying hard to be invisible. Finally, we headed towards a great horned owl nest site known to have a single chick nearly fledged. As we approached, there was nothing to be seen but the remains of a rabbit. We approached further, and were startled by a startled young owl as it took off from a nearby perch, impressed us with its wingspan, and flew clumsily out of view. Another fledgling confirmed, and our work for the day done. Gavin will continue monitoring until breeding success can be confirmed at many more nest sites for as many as a dozen different raptor species around the park.  Hopefully he will find the raptor population in Pinnacles as blissfully stable today as it has been since monitoring began more than 20 years ago.

-Jessica Weinberg


Posted by: pointreyesscience | June 21, 2010

Silence of the owls

What I learned today: Like Hannibal Lecter, owls love liver.

The Northern spotted owl is listed as threatened under the federal Endangered Species Act. Photo credit: John and Karen Hollingsworth, U.S. Fish and Wildlife Service.

I watched the adult Northern spotted owl through my binoculars, and all I could think was, “How majestic!” The owl was about the size of a footstool with wide wings. It was craning its neck toward us with a look of bored disdain.

The fledgling perched next to the adult on the Douglas fir was in its awkward pre-teens. It was a ball of white fluff—the sort of thing you’d expect to find at the back of your clothes dryer. It demanded another helping of food with a raspy screech. The adult complied, yanking a smooth orb from the belly of the wood rat clamped in its talons. The fledgling nipped the orb out of the adult’s beak and swallowed it whole. Majestic, indeed.

Marin County, Calif. is the southernmost point in the Northern spotted owl’s range. Here, the owl roosts in firs and redwoods. While it prefers to feast on Point Reyes National Seashore’s abundant woodrats, the owl will also sneak ordinary rats and other critters from nearby farm buildings.

For over 100 years, logging has chipped away at Northern spotted owl habitats. With owl numbers in a dive, the federal government listed the bird as threatened under the Endangered Species Act in 1990. But logging isn’t the owl’s only concern. Over decades, a second owl native to the East Coast called the barred owl creeped across Canada then turned south to Washington and Oregon. The barred owl is a tougher specimen than the spotted owl and better suited for an owl civil war.

With the Northern spotted owl perched precariously in the Pacific Northwest, the National Park Service has been keeping a close eye on its populations. The service’s Inventory and Monitoring program tracks spotted owl pairs as they mate, nest and raise young. Not every nest is as lucky as the one we’re watching today. Predators often devour eggs or chicks when the adults are out on the hunt for food.

The woodrat is all gone, and this fledgling is quiet—for now. Its fat belly is hanging over its talons. Perhaps, next time it’ll take its liver with some fava beans and a nice glass of Chianti.

-Daniel Strain

Posted by: pointreyesscience | June 21, 2010

(Slow) march of the snails

A group of black turban snails congregate in a tidepool nook. Photo credit: Steve Lonhart (SIMoN/MBNMS)

For Point Reyes’ intertidal snails, it’s a hard knock life—literally. First, they contend with crashing waves and flying spray. Then come the hungry seabirds. Finally, snails spend hours inching across, well, inches of rock only to see their journeys come to a sudden stop in the fingers of a researcher.

The lima bean-sized angular unicorn snail, marble-shaped black turban snail or the periwinkle, barely bigger than a grain of sand, are citizens of some of California’s most diverse natural communities. They crawl around and over algae, mussels, crabs, barnacles, sea stars, anemones, limpets, chitons and countless other plants and animals during their slow sojourns. As threats to oceans rise, protecting this menagerie has become a top goal of staff at Point Reyes National Seashore.

Each year, researchers set out to census tidepools up and down the coast of California. The goal isn’t to frustrate snails but to keep an eye on the health of these eclectic communities. Over time, scientists will be able to watch as mussels creep toward the ocean or draw back and as algae grows thick or thin.

Today, I and four park service staffers are out on Santa Maria Creek, south of Limantour Beach at low-tide. Dry in our waders, we peel through squishy algae cover or peek through the breaks between muscles for mobile tidepool residents like limpets and chitons. Limpets look like seashells fastened tight to rock or sometimes to the tops of mussels. They barely budge when I give them a poke. Chitons shield themselves with smooth armor traced with horizontal lines.

Then there are the snails. We pluck them from their hiding places to measure them from one end of their shell to the other. But, just as the snails think all their efforts were for nothing, we gently put them down where we found them. Our snails are back to their long and winding road and, sitting at the end of it, friends and family eager to hear about their adventures.

-Daniel Strain

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