The famous Sharktooth Hill Bone Bed near Bakersfield has tantalized the imagination of scientists and laymen alike since it was first discovered in the 1850s. How did a six-to-20-inch-thick layer of fossil bones, gigantic shark teeth and turtle shells three times the size of today’s leatherbacks come to be?

Was this a killing ground for C. megalodon, a 40-foot long shark that roamed the seas until 1.5 million years ago? Perhaps a great catastrophe like a red tide or volcanic eruption led to animal mass-death in the region? Or is this simply the result of Sharktooth Hill being used as a breeding ground for generations of marine mammals throughout the millennia?

A research team consisting of palaeontologists from the United States and Canada are now offering their take on the Bone Bed, suggesting it is not the result of a sudden die-off or a certain predator. Instead, the North American team sees it as a 700,000-year record of normal life and death, kept free of sediment by unusual climatic conditions between 15 million and 16 million years ago.

The research team bases its hypothesis on a new and extensive study of the fossils and the geology of Sharktooth Hill. Roughly 3,000 fossilized bone and teeth specimens found in various museums, including the Natural History Museum of Los Angeles County (NHM) and UC Berkeley’s Museum of Paleontology (UCMP), have been scrutinized, and the researchers also cut out a meter-square section of the bone bed, complete with the rock layers above and below.

“If you look at the geology of this fossil bed, it’s not intuitive how it formed,” says Nicholas Pyenson, a former UC Berkeley graduate student who is now a post-doctoral fellow at the University of British Columbia. “We really put together all lines of evidence, with the fossil evidence being a big part of it, to obtain a snapshot of that period of time.”

The existence of a 700,000-year window through which we can catch a glimpse of the past is naturally magnificent news for anyone interested in evolution and Earth’s history.

When the Central Valley was a sea

When the Sharktooth Hill Bone Bed formed between 15,900,000 and 15,200,000 years ago, the climate was warming up, ice was melting and the sea level was much higher than today. What is today California’s Central Valley was an inland sea with the emerging Sierra Nevada as its shoreline.

After closely examining the geology of the Sharktooth Hill area, the research team was able to confirm that it had once been a submerged shelf inside a large embayment, directly opposite a wide opening to the sea.

Several feet of mudstone interlaced with shrimp burrows is present under the bone bed, which is typical of ocean floor sediment several hundred to several thousand feet below the surface. Inside the bone bed, most of the bones have separated joints, indicating that they have been scattered by currents.

“The bones look a bit rotten, as if they lay on the seafloor for a long time and were

abraded by water with sand in it“, says UC Berkeley integrative biology professor Jere Lipps.

Many bones also had manganese nodules and growths on them, something which can form when bones sit in sea water for a long time before they are covered by sediment. According to the team, the most likely explanation for this is that the bones have lain exposed on the ocean floor for 100,000 to 700,000 years while currents have carried sediment around the bone bed. The prevailing climatic conditions at the time have made it possible for the bones to accumulate in a big and shifting pile at the bottom of the sea.

“These animals were dying over the whole area, but no sediment deposition was going on, possibly related to rising sea levels that snuffed out silt and sand deposition or restricted it to the very near-shore environment,” says Pyenson. “Once sea level started going down, then more sediment began to erode from near shore.”

The team discards the breeding-ground hypothesis due to the scarcity of remains from young and juvenile animals. Hungry Megalodon sharks being the main contributors to the bone pile is also unlikely, since few bones bear any marks of shark bites. If the bone bed was the result of mass-death caused by an erupting volcano the absence of volcanic ash in the bed would be very difficult to explain, and the presence of land animals like horses and tapirs that must have washed out to sea make the red-tide hypothesis equally thin.

Amazing remains from the past

The Sharktooth Hill Bone Bed covers nearly 50 square miles just outside and northeast of Bakersfield in California and is one of the richest and most extensive marine deposits of bones in the world. Studied parts of the bone bed average 200 bones per square meter, most of them larger bones. Ten miles of the bed is exposed, and the uppermost part of the bed contains complete, articulated skeletons of whales and seals.

Within the bone bed, scientists have found bones from many species that are now extinct and the bed provides us with invaluable information about the evolutionary history of whales, seals, dolphins, and other marine mammals, as well as of turtles, seabirds and fish. Sharktooth Hill is naturally the sight of some impressive shark findings too, including shark teeth as big as a hand and weighing a pound each.

A small portion of the bone bed was added to the National Natural Landmark registry in 1976 but the rest is in dire need of protection.

A collaborative effort

The research team, who’s study will be published in the June 2009 issue of the journal

Geology, consisted of:

– UC Berkeley integrative biology professor Jere Lipps, who is also a faculty curator in UC Berkeley’s Museum of Paleontology.

– Nicholas Pyenson, a UC Berkeley Ph.D who is now a post-doctoral fellow at the University of British Columbia.

– Randall B. Irmis, a UC Berkeley Ph.D who is now an assistant professor of geology and geophysics at the University of Utah.

– Lawrence G. Barnes, Samuel A. McLeod, and Edward D. Mitchell Jr., three UC Berkeley Ph.D’s who are now with the Department of Vertebrate Paleontology at the Natural History Museum of Los Angeles County.

Eleven suspected abalone poachers have been arrested in northern California, officials said Friday.

Since the tide was unusually low in Mendocino County, California Department of Fish & Game wardens were aware of the increased risk of poaching activity and kept their eyes on the coast line, including the coral reefs that had become exposed as the water disappeared.

At about 6.15 a.m. on Wednesday wardens noticed suspicious divers exiting waters near Caspar, south of Fort Bragg. Fish & Game Lt. Kathy Ponting, who runs the special operations unit, said her team drove to a spot near the suspicious divers and began surveillance.

Unaware of the wardens’ presence, the divers collected abalone from the reef and placed them in tall grass near the beach.

“Then a large van pulled up near the dive area and we watched them load up a bunch of abalone in plastic bags into the van,” Ponting said. The divers went back to the sea, while wardens decided to follow the van. After pulling it over, they discovered 50 abalones inside.

Abalones can sell for up to $100 dollars, but collection is strictly regulated since these molluscs need many years to develop. It can take 12 years for a specimen to reach the legal size. With a California fishing license and an abalone stamp card you are allowed to fetch 24 specimens per year, but no more than three per day. It is also illegal to collect them for sale, and anyone caught with a dozen or more will be considered possessing them with the intention of selling them.

Red Abalone. The only type that can be harvested.

When the van did not return to the divers, the alleged poachers loaded a pickup truck. The wardens followed the car to a nearby hotel and found coolers filled with abalone inside the divers’ hotel room. Most of the abalones were smaller than the legal size.

The wardens found a total of 166 abalones with the group, Ponting said. The suspects were booked on charges of felony conspiracy to harvest abalone for commercial purposes, which carries a fine of up to $40,000, said Game Warden Patrick Foy. Two vehicles also were

seized along with $6,000 in cash.

The black market for abalone is large and poaching is widespread, despite official efforts to eradicate the practise.

“We always only catch the tip of the iceberg, there is so much

abalone poaching going on because of the black market,” Ponting

explained. “We can pick almost any group and watch them poaching

abalone. It’s really unsettling.”

What is an abalone?

The abalone is a medium sized to very large edible sea snail prized for its exquisite flavour. There is roughly 100 known species world wide, all of them being gastropod molluscs belonging to the genus Haliotis. You may stumble upon a species marketed as “Chilean abalone” in the food trade, but this is not a real abalone; its name is Concholepas concholepas and it belongs to an entirely different family.

Since abalones are found in so many different parts of the world, they are known under many different names, such as abulón in Spanish, ormer in Jersey and Guernsey, pāua in

New Zealand, muttonfish or muttonshells in Australia, perlemoen in South Africa, and Venus’s-ears, ear-shells, and sea-ears in British and American English.

Abalones reach sexual maturity when they are comparatively small, but they won’t produce any significant amount of offspring until they grow bigger. A small abalone may release around 10,000 eggs at a time, which may sound like a big number but is dwarfed compared to the 11 million eggs released at a time by really large abalones. As a result of this, the removal of abalones from the sea before they have a chance to grow large is highly detrimental to the survival of the species.

Abalone has been farmed since the 1950s in Japan and China, and during the 1990s the practise spread to other parts of the world in response to dwindling wild populations. Today, it is possible to purchase farmed abalone and refrain from removing specimens from the wild. China and Japan are still major producers of abalone, but has been joined by Korea, Thailand, Australia, New Zealand, South Africa, Namibia, Iceland, Ireland, Canada, USA, Mexico, and Chile.

Catching abalone in California

As mentioned above, it is legal to fetch a certain amount of abalone per day and year in Californian waters if you have a California fishing license and an abalone stamp card. The abalone stamp card has 24 tags and captured abalones must be tagged immediately. The legal size is (a minimum of) seven inches (178 mm) measured across the shell. A person may be in possession of no more than three abalones at any given time. Other regulations to keep in mind are listed below. Always check with the California Department of Fish & Game before you go abalone hunting in California to find out if there have been any regulatory changes.

· Scuba diving for abalone is always prohibited; you may only pick them from the shore or use breath-hold techniques.

· Abalone may only be taken from April to November, not including July.

· You may only take Red abalones; no Black, White, Pink, or Flat abalones.

· You may not take any abalones south of the mouth of the San Francisco Bay.

· You may not sell any part of the abalone, including the shell.

· Only abalones still attached to the shell can be legally transported.

Genetic pattern analysis strongly suggests that California and British Columbia urchins are not connected via larval dispersal and comprise two distinct populations. Sea urchins have one of the longest larval periods of any known marine invertebrate and it has therefore been tempting to assume that ocean currents must be mixing urchin larvae all over the place, making it difficult for any distinct populations to form. But research results from the University of California now indicate that these two Pacific populations are two clearly separated ones.

Sea urchins –  Picture from the Red Sea

Together with former* graduate student Celeste Benham, marine biology professor Ron Burton of the University of California at San Diego have analyzed 500 adult sea urchins from Californian waters across five microsatellite markers and then compared the genetic patterns to an existing, similar database of 1,400 urchins from British Columbia. The Californian specimens were collected off the coast of San Diego, Los Angeles and Mendocino counties.

The genetic signatures found by Burton and Benham strongly suggest that the southern and northern populations are not connected via larval dispersal.

“From my evolutionary perspective, our results are important because they imply that, even on long time scales, there is no mixing, Burton explains. This means there is at least the potential for populations to adapt to different ocean conditions and gradually diverge. This is the first step in the two populations potentially becoming different species.”

This is the first time scientists have detected any population structure in the species. Similar studies carried out in the past have used fewer genetic markers and found no population genetics structure in the species despite having tested many different patches across its range.

“The take-home message of this study is that if you use more markers and newer techniques you will find some population differentiation that before nobody found,” says Burton.

* Benham is now a research assistant at the marine mammal laboratory at Hubbs-SeaWorld Research Institute in San Diego.

U.S. and Canadian scientists have documented the first known migration of blue whales from the coast of California to areas off British Columbia and the Gulf of Alaska since the 1965 ban of commercial whaling.

Researchers identified 15 separate cases where Blue Whales were spotted in the waters off British Columbia and the Gulf of Alaska. Four of the observed animals were identified as Blue Whales previously seen swimming in Californian waters, which suggests that Blue Whales are re-establishing their old migration pattern.

The identifications were made by comparing pictures of Blue Whales photographed in the northern parts of the Pacific Ocean since 1997 with photographs of Blue Whales taken off the southern U.S. West Coast. The identity of individual Blue Whales was determined based on dorsal fin shape and pigmentation patterns in skin colour.

The Blue Whale was almost hunted to extinction during the 20^th century and even though commercial whaling has been prohibited (albeit not strictly enforced) since 1965 the populations are having a hard time recovering. Blue Whales are still listed as endangered on the IUCN Red List of Threatened Species and no more than roughly 5,000 to 12,000 Blue Whales are believed to remain in our oceans, with 2,000 of them living of the U.S. West Coast.

The migration research was conducted by scientists from Cascadia Research Collective in Washington State, NOAA’s* Southwest Fisheries Science Center in California, and Canada’s Department of Fisheries and Oceans. You can read the full article in the most recent issue of the journal Marine Mammal Science.

* The United States National Oceanic and Atmospheric Administration (NOAA)

A New Jersey woman whose diet consisted almost exclusively of canned tuna for five years can sue a tuna fish producer over the mercury poisoning she allegedly suffered from, the U.S. Supreme Court said Monday.

Deborah Fellner sued Tri-Union Seafoods LLC under the New Jersey Product Liability Act for failing to warn her of the dangers of eating the company’s canned albacore tuna. She claimed that the Tri-Union Seafoods tuna products that she ate from 1999 to 2004 contained methylmercury and other harmful compounds which caused her injury.

California-based Tri-Union Seafoods LLC, who market their products under the “Chicken of the Sea” brand, said the company was not responsible for her claimed illness, arguing that the U.S. Food and Drug Administration does not consider canned tuna fish worthy of mercury warnings to consumers. The company referenced a 2005 letter the FDA sent former California Attorney General Bill Lockyer* that said state-mandated mercury warning labels were pre-empted by federal law.

The law suit was thrown out by U.S. District Court Judge Dennis Cavanaugh, but the 3rd U.S. Circuit Court of Appeals reinstated the class action.

“State law is not pre-empted whenever an agency has merely ‘studied’ or ‘considered’ an issue; state law is pre-empted when federal law conflicts with state law,” 3rd U.S. Circuit Senior Judge Walter Stapleton wrote for the appeals court.

In response to the ruling of the 3rd U.S. Circuit Court of Appeals, Tri-Union Seafoods asked the U.S. Supreme Court to review the case and the justices have now allowed the appeals court ruling to stand. The U.S. Supreme Court has not commented on their decision.

* Lockyer was trying to sue three tuna producers (one of them being Tri-Union Seafoods) for not complying with California’s Proposition 65. According to Proposition 65, businesses must provide “clear and reasonable” warnings before exposing people to known carcinogens or reproductive toxins.

War on clams has been declared at Lake Tahoe, a large freshwater lake in the Sierra Nevada Mountains of the United States. Scuba divers have been enrolled in a 400,000 USD project aiming to completely rid the lake of all Asian clams. The anti-clam endeavour is scheduled to begin in mid-March and is a combined effort by the governments of Nevada and California.

The Asian clam (Corbicula fluminea) is native to Asia and parts of Africa where it inhabits streams, canals and lakes. In this part of the world it is a natural part of the ecosystems and is even known as the prosperity clam or good luck clam. The Asian clam was introduced to North America in the 1920s by Asian immigrants for whom it was an appreciated source of food. It would however take until 2001 before the first specimens were encountered in Lake Tahoe. Since the first finding, the clam has been collected from numerous locations Tahoe’s southeast shore and authorities now fear that it will pave the way for even more dangerous invasive species such as the Ukrainian Quagga mussel (Dreissena rostriformis bugensis) and the Russian Zebra mussel (Dreissena polymorpha).

”We’re concerned they could create a positive settlement situation for the quagga mussels,” says Steve Chilton, aquatic invasive species coordinator for the U.S. Fish and Wildlife Service. ”We’re basically looking at all avenues through which the quagga mussel could get into the lake and eliminate that risk factor as much as possible.”

Steps so far have primarily focused on mandatory boat inspections to ensure no mussels are attached to them when they launch into the lake, but scuba divers participating in the new anti-clam project will actually be removing Asian clams from Lake Tahoe’s southeast shore. Starting in mid-March, divers will place plastic sheets, so called bottom barriers, over selected clam beds in order to deprive the clams of oxygen and nutrients. Divers will also carry out ”diver-assisted suction”, e.g. manually vacuum clams off the bottom of Tahoe.

”This needs to be done. We have to get our hands around the Asian clam problem,” Tahoe Regional Planning Agency spokesman Dennis Oliver told the Reno Gazette-Journal. ”We need to find out what works and what works best. Once we know that, we can develop a program.”

Invasive mussel species are known to form huge populations in environments where they lack natural predators and can for instance clog water intakes, attach themselves to boats and docks, and litter sandy beaches.

North America is not the only continent with an Asian mussel problem; Corbicula fluminea has begun to spread throughout Europe as well. It was found in the Rhine as early in the 1980s and then gradually found its way into the Danube through the Rhine-Maine-Danube Canal. In 1998 the first specimens were found in the Elbe and the species is now also present in the rivers of Portugal.

The U.S. Bureau of Reclamation is now carrying out tests in hope of finding out if bacteria can aid them in their struggle against invasive mussel species that are threatening to spread across the West’s waterways.

During the summer of 2008, a preliminary test was executed at Davis Dam on the Colorado River at Laughlin in Nevada. In this dam, Quagga mussels (Dreissena rostriformis bugensis) were exposed to dead bacteria of the Pseudomonas fluorescens species, a non-infectious bacterium that is commonly found in water, soil and food.

Quagga Mussels

During the first test the mussels where exposed to bacteria in jars, but the next test will take place in 10-20 gallon aquariums to in order to more accurately mimic real dam conditions. Water will flow through the aquariums, but will not be released back into the river – it will instead be disposed of through an evaporation pond. A third experiment is also planned, where bacteria will be released in a domestic water intake line which is currently encrusted with a 2-3 inches thick layer of mussels (approximately 5-7.5 cm).

“We are always looking for new, more effective techniques for managing mussels, and this one looks very safe and very promising,” says Reclamation scientist Fred Nibling. “We’ll have a series of tests where we’re going to be testing off-line, off the river, so we can have the data to where we can apply for the permits to test elsewhere.

If the initial testing proves to be successful, the Bureau of Reclamation hopes to have a larger scale test approved by the Environmental Protection Agency.

The U.S. Bureau of Reclamation got the idea to use Pseudomonas fluorescens from Daniel Molloy, a researcher at the New York State Museum who discovered that both zebra and quagga mussels died if they ingest the bacterium. He confirmed the effect in 1998 and the method was patented by the museum. Eventually, the Californian firm Marrone Organic Innovations was awarded a National Science Foundation grant to commercialize the technology.

According to Molloy’s research, a mussel needs to ingest a high density of a strain of the bacteria in order for the bacteria to be lethal. If the density is high enough, a toxin inside the bacterium cell will efficiently devastate the digestive tract of the animal.

One advantage with Pseudomonas fluorescens compared to conventional anti-mussel treatments like chlorine is that mussels recognize chlorine as dangerous and close their feeding valves to keep the chemical out. They do however happily devour Pseudomonas fluorescens. Another important aspect is that research has found that Pseudomonas fluorescens does not kill fish or shellfish.

If large scale testing also proves successful, the Bureau of Reclamation say they wish to meet with municipal public works and water authority officials before the bacterium is put into general use. “We want to make sure they’re very comfortable and they have a chance to ask questions,” says Nibbling.

Zebra mussels

In addition to the recently proposed areas in the Pacific Ocean, (See this and this) president Bush now says he wants to find even more regions of the Pacific Ocean to protect.

This Friday, Bush made public that he has asked the secretaries of the Interior, Commerce and Defense to identify additional areas of the Pacific Ocean that could be eligible for conservation. He also revealed that the Monterey Bay National Marine Sanctuary will be expanded by 585 square nautical miles and come to include the Davidson Seamount. Davidson Seamount is a 42 km long underwater mountain located roughly 120 km southwest of Monterey, California. The seamount rises 2400 meters off the ocean floor, but its highest point is still more than a kilometre below the surface.

This week, Science published the study “Can Catch Shares Prevent Fisheries Collapse?” by Costello[1], Gaine[2] and Lynham[3], which may be used as a road map for federal and regional fisheries managers interested in reversing years of declining fish stocks.

The study has already received a lot of praise from environmental groups, including the Environmental Defense Fund (EDF) who says that the study shows how the overfishing problem can be fixed by implementing catch shares. “We can turn a dire situation into an enormous opportunity to promote better food security, create jobs and revive ecosystems,” says David Festa, vice president and director of the oceans program at EDF.

Catch share programs is intended to replace complex fishing rules and hold fishermen directly accountable for meeting scientifically determined catch limits. In a catch share program, fishermen are granted a percentage share of the total allowable catch, individually or in cooperatives. They can also be given exclusive access to particular fishing zones, so called territorial use rights. As long as the fishermen do not harvest more than their assigned share, they will retain a comparatively high flexibility and decide for themselves when to carry out the fishing, e.g. depending on market fluctuations and weather conditions.

“The trend around the world has been to fish the oceans until the fish are gone,” says Festa. “The scientific data presented today shows we can turn this pattern on its head. Anyone who cares about saving fisheries and fishing jobs will find this study highly motivating.”

As the fishery improves, each fisherman will find that the value of his or her share grows. This means that fishermen will be financially motivated to meet conservational goals.

In January 2007, a catch share system for red snapper went into effect in the Gulf of Mexico, causing the 2007 commercial snapper season to be open 12 months a year for the first time since 1990. According to EDF, fishermen in the area now earn 25% more and wasteful bycatch has dropped by at least 70%.

For reasons unknown, massive groups of Humboldt Squid have left their native waters in South America and can now be found all the way up to Alaskan waters. The Humboldt Squid is most commonly found between Tierra del Fuego at the southernmost tip of the South American and the U.S. state of California. Recent findings do however suggest that the species is spreading north into the waters of Oregon, Washington, British Columbia and even Alaska.

The Humboldt Squid can reach a size of 2 meters (7 feet) and weigh 45 kg (100 pounds). Due to its impressive size, it is known under names such as Jumbo Squid and Jumbo Flying Squid. In Spanish speaking parts of South America, it is called Diablo Rojo which means Red Devil. The creature is equipped with 10 arms and a really sharp beak. It is known for its aggressiveness, but research suggests that these animals are only aggressive during feeding time. During feeding frenzies, they have no problem retorting to cannibalism. When not feeding, they seem to be fairly docile.

If you want to learn more about this aggressive predatory squid and its newfound wanderlust, KQED has devoted the Season 2 Web Premiere of the program QUEST to the Humboldt Squid (Dosidicus gigas). QUEST is a TV, radio, web, and education series that explores science, environment and nature in Northern California. You can find the episode here: http://www.kqed.org/quest/blog/2008/03/26/quest-season-2-web-premiere-the-fierce-humboldt-squid/