Current Projects   

As Collection Manager of the microfossil collection at UCMP, my primary task is to organize and database a century's accumulation of slides, samples, documents, and literature so that this wealth of information can be readily accessed for research and teaching at the museum and via the internet. There are hundreds of thousands of slides containing millions (billions?) of specimens awaiting my attention. Hopefully, my eyesight and sanity will last long enough to fulfill a significant part of this mission before my own fossilization ensues! You can visit the now rapidly expanding microfossil database and learn more about these and considerably larger fossils at the UCMP website.

Although I have worked with all kinds of fossils in my career as a paleontologist, as a Senior Museum Scientis at UCMP, my research interests have been in the field of micropaleontology, particularly on the Foraminifera and Ostracoda, although I have recently delved into the wonderful world of diatoms. I am currently involved in projects on the Tertiary of Chile (see those completed in Selected Publications) and the Quaternary of California. The latter studies are described below.


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Several years after Samuel Merritt dammed this former tidal slough in 1869 and began developing its surrounding wetland, flaws in his "Jewel of Oakland" became unpleasantly evident as silt and algae accumulated. Although part of it was designated as the nation's first wildlife refuge (protecting more than 90 species of migrating waterfowl), Lake Merritt also serves as a drainage basin for the regional flood control system, receiving urban runoff from a 4,650 acre watershed through 60 storm drain outfalls. Four culverted creeks drain into this 145-acre lagoon from the east, while tidegates regulate flow through a narrow channel connecting it with Oakland Inner Harbor and San Francisco Bay. The lagoon is also polluted by illegal dumping of substances toxic to marine life, such as paints, solvents, and oil. In addition to mechanical harvesting of its widgeon grass, 1,000 to 7,000 pounds of trash are removed from Lake Merritt every month.

Anticipating remediation efforts by the City of Oakland, Jere Lipps and I realized there was an opportunity here to study before and after effects on the microfauna. Several other studies have revealed foraminiferal responses to pollutants, suggesting their utility as environmental monitors. I have recognized 27 species of Foraminifera, whereas the late Dawn Peterson had identified 22 species of Ostracoda. About half of each group comprises species that are inhabitants of the lagoon; the rest are normal marine foraminifers tidal-transported from San Francisco Bay, and freshwater ostracodes imported by drainage from the Oakland watershed. The more common species (shown below) are typical inhabitants of hyposaline waters. Histologic staining reveals that the majority of our assemblages from depths below one meter were devoid of living specimens when collected. Most of the living specimens were recovered from water depths less than a meter in the tidal inlet and along the margins of the lagoon where and there are visible signs of life, such as algae and mussels. Data obtained with a YSI 85DŽ water monitoring probe confirms that stratification of the water column results in an unmixed deeper layer characterized by low levels of dissolved oxygen. The decay of organics on the bottom of the lagoon depletes the oxygen and releases hydrogen sulfide that bubbles to the surface, and which is evident in the unpleasant odor and dark color of the mud samples. We suspect most of the deeper assemblages were created by post-mortem transport from the shallow margins, but we cannot rule out the possibility of intermittent mass mortalities when dissolved oxygen levels drop below a tolerable threshold.

Unlike foraminiferal assemblages in the bay, those in Lake Merritt often include malformed specimens, but surprisingly in lower relative abundance than typically reported from stressed environments where they have been linked to high levels of contaminants, heavy metals, industrial pollution, and domestic sewage.

Views of Lake Merritt

Lake View 1

Lake View 2

Lake View 3

Jere sampling

Dawn sampling

Tidal inlet

Surface oil film


Microfauna from Lake Merritt


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Located in Lake County north of San Francisco, Clear Lake is one of the world’s oldest freshwater lakes, having a sedimentary sequence that spans the past 500,000 years. In 2012, UC Berkeley contracted to have two 120-meter (400-foot) cores drilled in the center of lake for study by a diversity of its scientists, including paleontologists, palynologists, botanists, ecologists, and climate modeling experts, to detail how its biota responded to past changes in climate. The data will be used to improve models that project how life on Earth will adapt in the future. This is essential for the formulation of policies designed to preserve ecosystems threatened by climate change. The geologic record shows us that global warming is accompanied by the flooding of coastal areas, desiccation of formerly verdant land, and widespread fires. If the current rate of warming continues, these consequences could occur on a scale that will have devastating effects on humankind.

The Clear Lake cores record at least 130,000 years of biotic change in the lake. Unlike those obtained by the US Geological Survey in 1973 and 1980, which were sampled approximately every meter (~1000 years), parts of the new cores have been sampled every centimeter (~10 years) for higher resolution study. Isotope and chemical analyses, including carbon dating of charcoal, are providing age horizons for correlation with the geologic time scale and measures of temperature, oxygen content, and nutrient levels of the lake. Changes in these parameters and the biota they affect reflect past fluctuations in climate, most notably the dry, cold glacial stages vs. the wet, warm interglacial stades.

Biologist Jack Sculley and I are studying the diatom sequences to determine their utility as environmental proxies. Initially, our focus is on the shift from the last glacial to the current interglacial 13,000-11,000 years ago because its rate of global warming is similar to that of the modern world. We have identified more than 100 diatom species (see photos below; some IDs tentative). In addition to any species-specific environmental indications, there are two general aspects of the microflora will we be investigating: (1) centric (symmetrically round) forms are phytoplankton that exhibit spring blooms represented by their intermittent abundance peaks in the stratigraphic sequence; (2) pennate (non-centric) forms inhabit streams and lake margins, so their relative abundance will be used as an indicator of increased inflow during warmer, wetter intervals during which they would have been displaced into the center of the lake. These patterns will then be compared with the results of Roger Byrne's pollen analysis.


Symmetrical Biraphids

Navicula & Pinnularia


Asymmetrical Biraphids & Nitzchioids

Eunotioids & Epithemioids

Araphids & Surirelloids

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