Back in the Bay

River Otters:  Back on the Bay Area Map!
Guest Speaker: Robyn Aston, River Otter Ecology Project
7pm November 19th, 2015
FREE Lake Merritt Rotary Nature Center, Oakland, CA 

River otters are charismatic carnivores, and make wonderful ambassadors for river and wetland restoration and conservation efforts. Once extirpated in the SF Bay Area, little is known about their current population, range, and seasonal eating habits. The River Otter Ecology Project has taken on the challenge of discovering and documenting their ecological niche, with the goal of informing land use decisions and preserving habitat for these lively aquatic mammals.

Join us as we discuss what we know, what needs to be discovered, and just how we manage to research elusive, secretive mammals who slide into the water and disappear when approached. We will show slides and videos from our “otter-cams,” and discuss the project and the role that citizen science plays in this otterly exciting work!

More about Robert “Robyn” Aston

The River Otter Ecology Project (ROEP)
Otter Specialist Group, International Union for Conservation of Nature (IUCN)

Robyn Aston, interested in otters from an early age, has a degree in Biology, and is currently a volunteer with ROEP. His duties include working in the field, maintaining a River Otter research database, and presenting to schools, universities, and special interest groups. Along with many of the world’s leading “otter-ologists,” he, and ROEP Director Megan Isadore, are members of the IUCN’s Otter Specialist Group.


The Location

Lake Merritt’s Rotary Nature Center is at 600 Bellevue Avenue in Oakland. On the Northern shore of Lake Merritt (between it’s two “arms”). Part of the City of Oakland’s Office of Parks and Recreation, the Center is an interpretive museum, providing education about the natural environment while overseeing America’s oldest wildlife refuge and Oakland open spaces. A City of Oakland, Office of Parks and Recreation entity.

We are grateful for their offer of their space. An otter appeared briefly in the Lake a couple years ago — we hope they’ll come back for longer sometime in the future!

The Nature Center is about a 20 minute walk from 19th St BART station. Closest bus line from the direction of BART is the NL or the 12. There is street parking.

Our first ever video recorded lecture — thanks to the San Francisco Public Library for hosting us, and providing this. Don’t get used to it though, most of our venues are not so high tech :)

Gregory Rosenthal joined us October 19th, 2015 to share his research into the early days of San Francisco. He started out as a scholar of China — but was looking for a place that China and the U.S. connected and landed upon Hawaii.

Kapalakiko — the transliteration of San Francisco in Hawaiian — was one node of a large Hawaiian diaspora in the mid to late 1800s. Hawaiian’s worked all around the Pacific — the large majority as whalers, in the arctic (where they were — perhaps unexpectedly — reliably the best workers), gathering guano, and active as workers and boatmen in California, with large numbers working the gold fields of California (Sutter had 10 Hawaiians in his employ).

This all evidenced by a number of Hawaiian language papers that were in circulation throughout the Pacific — which served as an important source of material for Gregory’s research. 90% percent of Hawaiian’s were literate in Hawaiian, and the papers served to connect the population that spread out over such large distances.

The 1860 census of San Francisco found that Hawaiians were the largest population next to whites. They weren’t just workers though — they were also landowners — although along with Mexicans — many had their land confiscated over time. While they were literate in Hawaiian — the “kanaka” — the term used for Hawaiian workers — weren’t necessarily literate in English and their employers often used this to their advantage (writing contracts in English without fully disclosing their contents).

He’s worked to bring their names back and humanize their story — helping to make San Francisco what it was from the very beginning.

Getting Underground

Bruce Rogers, a geologist and cave explorer from since he was a teen, came to us in September of 2015 to talk to us about caves. This was our last talk at the Exploratorium this year. The talk got off to a rocky start with not one but two fire alarms going off! We only had to evacuate once, but we were impressed by how many people (easily 90%) stuck it out.

Bruce starting with a definition of caves as underground, naturally occurring, with some parts in darkness, and humanly accessible. They have fascinated humans since probably long before we were even “human” (if the recent cave findings in South Africa have any bearing). For us they represent beauty, danger, and adventure, where of course for a long time they were likely refuges and homes.

Beyond that, to science and wider human interest they are even more interesting — they are geological repositories, they are workshops of evolution, they are archaeological sites, and holders of cultural treasures.

California has a few different types of caves across its landscape: limestone/marble caves, tafoni wind caves (tafoni is an italian word for small grottos built overlooking the ocean), sea caves, and fissure caves.

The ecology of caves can often be novel and fascinating, with new species often being described when new caves are found. Microbiology provides another level of this — with astrobiologists of late showing great interest in finding how life can live on in places like this, and where we might expect to find things alive on places like Mars.

There are creatures like the California giant salamander, one of the few salamanders to make noise. And of course bats — which Bruce in his cave explorations is careful not to disturb.

One cave near Monterey bay contained a graveyard of skunks, the skeletons of several thousand were found there in 1942. The skunks no longer seem to come back, but there are bats still in the cave. Mountain lions make use of caves in Big Basin.

Of course, all these caves are fragile, and their conservation is always a concern. He showed one example of cave that was discovered in 1954 (through an accident where someone got stuck, it soon became widely known) by 2007 everything had been broken off, the floors sledgehammered, full of garbage, and walls of graffiti. Spelunkers are now pretty wary of telling people of their finds, and recent caves opened to the public go to great lengths to preserve them from the outside. Caves do not renew — or at least not on any timescale we live on.

Sea caves are by far the most common type of cave in the Bay Area, created by the impact of waves along the bases of cliffs. Waves bring a tremendous amount of force to bear on cliffs. During hurricanes it can be enough to bend steel and smash concrete — but even a normal wave brings a lot more pressure to bear than most human activity.

Sea caves can be full of life, fish, seaweed, snails, limpets, anemones, mussels, barnacles, abalone, sea stars, sea lions (seals apparently don’t like caves). They can also be full of sand — the season, tide, and wave action can completely change a cave (he showed one picture of a cave with people standing upright in, and the next was someone crawling through the sand).

If you have an inclination to visit one — be wary! Be careful about the tide, and only go at extremely low tides.

There may be things to discover as well — At least there was… in 1927, a couple recovered some stolen silver in one of the sea caves. A stash of stolen goods from Hotels through San Francisco.

The Farallones also have some caves, quite large ones, with endemic species of a cave cricket and a salamander, and some very uncommon stalactites, and beautiful flowstone.

The only fissure cave he talked about is now on private land. There are not many limestone caves in the region either. The other most common cave type you will find in the Bay Area are tafoni caves — Castle Rock State Park have good examples, as well as Mt Diablo, and the Vasco Caves. The Vasco caves are part of a closed preserve: they have some 2000-4000 year old cave paintings and rare wildlife and plant species. You can get naturalist led tours of it in Spring and Fall.

If you want to know more about caves, preserving and exploring them, Bruce pointed us towards http://caves.org/

Brenda Goeden of BCDC and Ian Wren SF Bay Keepers joined us on August 19th, 2015 at the Exploratorium to to talk about what gets dredged out of the San Francisco Bay.

Most of the dredging that goes on in the bay is for navigation. This is mostly through mud — 80% of the Bay is fine grain mud, and it is dug out to allow deep draft vessels to come through, and keep waters by marina’s clear. The dredging aka mining of sand is mainly for the construction industry – it becomes cement, asphalt, road-base, sub-base and general fill. The grains of sand are grains (.002 to .08 inches in diameter) bigger than mud, and smaller than gravel. it gets mined on demand, not necessarily day in, day out.

There are two main areas whether the sand comes from: Suisun Bay and the Central Bay. Suisun Bay is a finer grain of sand which is often used for back fill in trenches. The coarser sand of the the Central Bay is used for cement. Sand is only found in the high flow areas of the Bay where the water has enough energy to carry the sand. Mud is taken out to the slow wide sides of the Bay.

Sand Flow in the Bay - Barnard et al. 2013

Sand is important for a number of reasons outside of its commercial uses — it helps build marshes and beach. It provides shoreline protection as it takes more energy to move, it provides a particular kind of habitat, and on the shore provides a place for recreation and having a place for viewing wildlife.

The amount of historical sand, and sand in the Bay is difficult to measure. Most of the sand in the Bay comes from the Delta and the larger watershed (40% of California’s watershed drains into the Bay), and estimated 1.2million cubic yards, with another 300+ thousand cubic yards coming from local streams. Where not blocked, the rivers and creeks, slide and bounce the sand along into the Bay.  Storms and other high flow events are key in moving the sand along and into the Bay and beyond.

The sand also is carried out into the ocean, and large dune field lays under water past the Golden Gate Bridge. This was once a wide delta of sand, but has been slowly growing smaller. This changing shape of this sand has affected how sand flows both inside and outside the Bay. The pattern of sand dispersal on Ocean Beach has meant the northern end of the beach has been gaining sand, and the southern has been losing sand leading to fast erosion of the shore. The bay itself is also losing some protection from ocean waves in this process as well. Crissy field on the other hand has benefited, gaining sand from both flows headed out to sea, and sand coming in along the shore.

There’s not a lot known about the habitat underwater in these sands. The Central Bay sand area is the deepest in the Bay 90′-300′ deep where the water is salty, deep, cold, and fast. Aka difficult to study (there has been some studies monitoring what is brought up by the sand miners). We know there are wondrous things going on down there, like the migration of Dungeness crabs — marching in to lay eggs, and then marching out again — but no one has ever seen it or knows the pathways.

Suisun Bay is shallower, warmer, and less salty. The two areas are pretty different, but in both cases these are deserts compared to the meadows of mud. The organisms living there tend to be smaller, efficient, and highly adapted.

Humans have had a huge impact on these fields of sand — the biggest being the pulse of sand brought down from the Sierra’s by gold miners, and estimated 10x the usual flow of sand. Before that, and before many of the rivers and streams were dammed. The flow might have been around 2 million cubic yards. The sand from mining continued to pulse through the system and is only recently pretty much all gone. Now a large portion of the pool of possible erodible materials is trapped behind dams and the delta tunnels.

We still have sand, and we still have sand coming in, but the question now is how much sand do we have, and how much can we afford to take out. Mining has been happening since the 30s, peaking in the years 1949-79. Much of the sand is used locally shipped to different dispersal points around the Bay.

Dredge mud goes to different places, a lot gets shipped and dumped out at sea, or dumped at certain disposal sites in the Bay itself (inside the bay this can disperse contaminants, cause turbidity). These are not the preferable options — that favored option (by BCDC) is helping restoration efforts, filling land that has sunk below sea level on the other side of levees. This is the unfortunately the most expensive option, which there are not a lot of funds for, and small marinas don’t tend to have funds to support that kind of work, and dredging for ports is an expensive enough business that any additional fees would likely be too onerous.

San Francisco Bay Keeper is involved in the issue, hoping to bring in the perspective of the overall health of the Bay and nearby waters, and the sand being an important part of it. The sand taken is not replenished, there is a net loss, and they want to make sure we keep relic sites, and keep mining more in active parts of the flow. They are also looking to insure there is proper compliance and that companies don’t end up taking more than they should. They are looking through commenting on proposals and active litigation to reduce the amount of sand mining going on — to being sand mining to a sustainable level.

On the flip side, if local industries turned to external sources for sand, there may be equally damaging impacts — leaving aside where the sand is being mined from, the carbon costs of shipping that sand by barge or truck would not be small.

The biggest question we seemed all left with was the complicated nature of the question. A unknown or at least unseen, but super valuable resource here in the Bay below us. How much is there? and how much can we afford to take out?

SF Bay Area Caves: A Ramble Through the Underground Realm
Guest Speaker: Bruce Rogers
7pm Wednesday, September 23rd, 2015 (doors open 6:30pm)
FREE at the Exploratorium Bay Observatory Gallery (see directions at the bottom for details)
and please let them know if you are coming.

Bruce Rogers will give us a scientist and explorer’s insight into selected caves of the Greater San Francisco Bay Region. The region is not noted for its abundance of known stygian sites, but they aren’t absent. Some you can visit and some you’ll likely never see for yourself, given the restricted access. We’ll include a quick look into the multitude of sea caves (some of national importance); tafoni shelters (a few with fascinating cultural and natural history); unusual caves comparable to only a few other locations world-wide; and even a scattering of small limestone caves and their unique inhabitants. Discussion will also touch on cultural and architectural sites resembling natural caves.

Elephant Bay Entrance, El Reyes Cave

Elephant Bay Entrance, El Reyes Cave

Bruce Rogers began cave exploring in the wilds of New England in 1958. Since then he has explored the basements of North America from the Atlantic to the Pacific and from Alaska to the Guatemala border in addition to many of the island nations of the Pacific Basin. All facets of geology and geography, cartography, photography, and history are included in his spelean interests. Author and/or editor of several books and scores of articles on caves, his current interests are lava tubes, littoral caves, cave history, and Pleistocene fossils in California caves. His interest in speleology led to formal geologic education and to a position as a field geologist at the USGS. There, he also indulged both artistic and scientific bents as a scientific illustrator and web person at the USGS for a third of a century. Since 2007, he has been writing prolifically and is President of the Western Cave Conservancy.


Reservations can be made at reserve@exploratorium.edu or 415-528-4444 option 5.

Please let the Gallery know if you are coming.

The lecture will be at the Exploratorium Bay Observatory Gallery at the back of the museum. The special event entrance is through the gate on the outside of building, past the main entrance (as depicted in the map). Someone should be out front helping guide (the museum itself will not be open). Please visit the Exploratorium website for directions to the museum.


Joel speaking at the Exploratorium

Joel spoke at the Exploratorium on July 15th, 2015 exploring in conversation and images “Seep City” – a catalog of water discoveries in the city of San Francisco.

Joel’s map of Seep City shows today’s landforms, but overlays the springs, water, and waterways of the past (I like how the map is a lacking in any streets — makes it funner to try and identify the places you know). Crissy field used to be much larger (the current marsh is a “sculpture of a marsh”), and there were large marshes on the eastern side of the city, a tidal waterway running up to the Mission District, and Islais creek wending it’s way into the peninsula. The sands also held many temporary lakes and water ways that would come and go with storms (and the shifting sands). They are barriers and dams, but could be blown away in a storm. Creeks flowing out of the dunes were often temporary or seasonal.

San Francisco — unlike a lot of cities — is not built on a river, and a question you might ask is why we have these seeps and springs at all. If you stripped all our human construction and put back features we’ve flattened or otherwise shaped, you’d find a lot of sand, as well as some serpentite and chert. Before all of our hardscape, rainwater would have been absorbed by sand and passed underneath it, but there is also water coming out of the tops of hills despite the drought. Joel still has yet to answer the question where this exactly comes from.

There were someplaces the water always flowed. The Ohlone, not a stone age people, but perhaps better described as people of the fabric age, made use of water based technology and had daily rituals washing in the creeks here. But there were only a few hundred there when the Spanish arrived.

The Spanish built their settlements in San Francisco around a couple of springs, in the Presidio and in the Mission. Captain Anza noted the spring that flowed out of the dunes near where the Mission was to be built was enough for a larger water wheel.

As the city developed, San Francisco used local water for laundries and for bottling, water was brought around the city through flumes built by private companies selling water to the more settled regions of the city. Lobos creek was one of the sources the flume running along the coast. Another had a water works that created stow lake. Safeway in the Mission/Castro area used to be a reservoir with water pumped over the hills from outside of San Francisco. Tank hill had a tank of water.

Water was also stored around the city for fighting the frequent fires of San Francisco’s early days. You may see the circle and square bricks circling intersections of San Francisco Streets. These continue to hold water for fighting fire.

Most of our water no comes from outside of San Francisco. The Presidio gets 80% of its water from its own springs. And lot of that water still flows, just mostly out of sight, channelized and covered over. There are of course many more water features now in the way of fountains and reservoirs, and some of that come from local water. The fountain in UN plaza (7 piles of stone representing the 7 continents apparently) actually runs on ground water that people refered to as Hayes Creek. BART has to pump water of its tunnels continually. Water runs under the Armory building in the Mission. There is a brewery at Haight and Steiner which hope to use the water underneath their store. The presidio has a creek you can shut it off in 3 places in case someone falls in.

This map is of course just a start, there are seeps and springs all over the city, and while this map holds many — Joel continues to hear of new possible springs and seeps. Keep up to date with this project at his website: seepcity.org

Understanding Sand Mining in SF Bay
Guest Speakers: Brenda Goeden and Ian Wren
7pm Wednesday, August 19th, 2015 (doors open 6:30pm)
FREE at the Exploratorium Bay Observatory Gallery (see directions at the bottom for details)
and please let them know if you are coming.

Sand mining in San Francisco Bay is a little known industry that has existed since the early part of the 20th century. Come learn about this activity that occurs in the deep subtidal areas of the Bay and provides sand for construction projects throughout the Bay Area. The talk will include some of the latest science, a discussion of mining effects on the marine environment and outer coast beaches, and a look at known concerns about sand mining. Ten-year permits for mining have recently been issued, so it’s a great time to understand the efforts and advances being made in the science and industry of local Bay sediments.

snippet of USGS relief map of part of SF Bay

Ian Wren is the Staff Scientist for San Francisco Baykeeper, which works to maintain a healthy ecosystem for wildlife and Bay Area communities. Ian is a hydrologist and works primarily on issues of stormwater, sediment management, nutrients and sea level rise. He has been involved in advocacy and litigation over impacts associated with sand mining and dredging and believes sustainable sediment management is critical to maintaining a thriving Bay ecosystem and economy in the 21st century.

Brenda Goeden is the Sediment Program Manager at the San Francisco Bay Conservation and Development Commission (BCDC). She supervises implementation of dredged sediment strategies. She works in collaboration with the regulatory and resource agencies in the Bay Area. Her work involves both site placement and quality testing. The BCDC was the first Coastal Zone Management Agency in the nation. They regulate Bay Fill and development, aiming to provide maximum feasible public access to the Bay.


Reservations can be made at reserve@exploratorium.edu or 415-528-4444 option 5.

Please let the Gallery know if you are coming.

The lecture will be at the Exploratorium Bay Observatory Gallery at the back of the museum. The special event entrance is through the gate on the outside of building, past the main entrance (as depicted in the map). Someone should be out front helping guide (the museum itself will not be open). Please visit the Exploratorium website for directions to the museum.



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