Volume 4, Issue 25 February 2007
The Sands of Time
A live specimen of a larger foraminifera from Papua New Guinea. About 1/2 inch long, it and has extended its pseudopodia, or "false feet," in the direction it is moving. JHL image, 1986.
Jere Lipps has an extraordinarily fine-grained view of history. As a professor of paleontology at UC Berkeley, Lipps examines records of the past written in layers of sediments and fossils. His work has shed light on ancient earthquakes and extinction patterns, the evolution of early life and even astrobiology, and taken him to more than 160 countries over the last 40 years.
The common thread to Lipps's far-ranging research? Foraminifera: tiny marine creatures easily mistaken for sand. Single-celled and quite separate from animals, foraminifera live in virtually every marine habitat explored by man. Even among scientists, foraminifera are chiefly known by their shells. These come in a galaxy of forms—stars and coils, turbans and disks, bulbous cones and simple tubes—segmented into chambers and pierced by patterns of pores. Some are built from secreted calcium carbonate; others are glued-together coral or sand. Their shapes are often distinct enough for Lipps to identify at a glance.
A common foraminifera, Trochammina hadai, found in San Francisco Bay. Lipps and colleagues found it was introduced accidentally to the bay 30 years ago in ship ballast water from Japan and had spread throughout the bay within about 15 years. (Scanning electron micrograph by Michele Weber.)
That type of mastery, however, doesn't come easy. By some estimates, foraminifera may have evolved into more than 80,000 species during their 545 million years on Earth.
Several qualities make foraminifera ideal markers of geologic history. In addition to being present virtually since marine animals first arose, "they're superabundant compared to the remains of clams or snails or dinosaurs. In a sample the size of a teaspoon, you can have thousands," Lipps says. Commercially, foraminifera are used in petroleum exploration, to find rocks that formed during the right conditions and timeframe to contain oil.
Forams are very picky about where they live. Many species can only survive a very narrow range of conditions, such as water of a certain temperature and salinity, or waves up to a certain strength. Distinct groupings allow Lipps to make extrapolations about long-ago ocean conditions and even geologic events.
Jere Lipps (right) and his research team, Lorraine Casazza (left) and Michele Weber, working on the Richmond marsh collecting foraminifera. JHL Image, 2004.
Recently, Lipps and his international team used foraminifera to analyze earthquake and tsunami frequency around the Pacific Rim. Alongside scientists from Alaska and Canada, Lipps examined shoreline sediment cores laid down over the past 7,000 years, at sites from Alaska to Baja California. By tracking changes in foraminifera over time, "we can know when the land goes up or down very precisely. If the edge of a marine plate gets bent down and the continent springs up, a marsh will go from marine to fresh water—then we see no more foraminifera."
Their findings should give coastal dwellers new respect for the watery giant next door. "We estimate that along our coast, from Alaska to Baja, we get a really big earthquake and tsunami every 200 to 300 years," Lipps says. Lipps has since expanded the project to New Zealand, Tahiti, and Mexico with scientists from those places.
Mangroves trees and marsh on the island of Moorea, French Polynesia, where Professor Lipps studies foraminifera. JHL image, 2002.
Lipps is also using foraminifera to gauge the health of UC Berkeley's Richmond Field Station marsh, the site of two former chemical factories. The University removed mud contaminated by heavy metals from the site in 2002. Lipps took sediment cores before the project began and has continued to sample it since. The marsh's comeback has been agonizingly slow, Lipps says. "I'm absolutely flabbergasted we're still looking at this, because foraminifera reproduce by the thousands. Every spring there's a bunch of juvenile ones, but they don't grow up—they just disappear." He ascribes their struggle to the fact that plants, which help keep the mud cool enough for foraminifera, haven't returned yet either.
Lipps's work frequently takes him much farther afield. His research sites read like a brochure for adventure travel—he scuba dives for specimens in places such as New Guinea, the Caribbean, Abu Dhabi, French Polynesia, and Antarctica, where a small island now bears his name.
In Middle Eastern waters and elsewhere, Lipps encountered carpetlike bacterial mats containing rounded formations formed by bubbles. These shapes looked disturbingly similar to what other scientists were calling fossils from some of the earliest marine lifeforms known—the jellyfish-like Ediacaran fauna of 555 million years ago. This led Lipps to study Ediacaran habitats and fossil formation.
Jere Lipps studying the habitats available in icy environments on Iceland. JHL image, 2005.
Lipps's work in Antarctica has directed him toward a more forward-thinking branch of science: astrobiology. "When the images of [Jupiter's moon] Europa came back showing it was a moon covered with water ice, I thought, I know all about those habitats," Lipps says. Using his experience studying ice shelf biota, Lipps developed what he calls a "paleontological search strategy" for NASA. "I and my colleagues came up with a list of 25 or so different habitats where resources might be available where organisms could live." Lipps's expertise in taphonomy, the preservation of organisms in rocks and ice, allowed him to hypothesize how these habitats might be preserved in the ice and uplifted to the surface for observation.
Living on Europa would be no picnic, but any organisms would be hard pressed to surpass the survival skills of foraminifera. "They live from the deepest parts of the ocean to the supratidal, from the poles to the equator, even in environments that have very little oxygen," Lipps says. It's no wonder he admires versatility and breadth—those same qualities have been the lodestones of Lipps's own long and eventful career.