Pharmaceuticals without a prescription.

As the population ages, healthcare spending swells, and medical technology advances, the use and variety of pharmaceuticals and personal care products (PPCPs) grow to meet the demand of people worldwide. Like all products, the presence of PPCPs in the environment has become as ubiquitous as their use in the human population. Today it is likely that PPCPs are detectable at low levels in all waterbodies adjacent to human settlement. In some instances they have been found to reach concentrations that rival pesticides.

PPCPs enter the environment primarily through the wastewater stream. When a pharmaceutical is administered to a patient, as much as 90% of the dose can be excreted still in its active form. Even the portion that is metabolized can be transformed and excreted as a unique byproduct. Personal care products like shampoos and lotions enter the wastewater stream when we wash our bodies and hands. This ever-changing concoction of chemicals, from analgesics to antibiotics, lipid regulators to synthetic musks, continuously buffets wastewater treatment plants, most of which are only designed to remove conventional pollutants and the basics of human waste. Due to the variety and the novelty of compounds found in PPCPs, many of these chemicals pass through traditional wastewater treatment plants unchanged and enter our streams, rivers, bays, and oceans. A 2009 study by the San Francisco Estuary Institute found 18 common PPCP compounds in treated wastewater effluent and surface water in the South San Francisco Bay. These included acetaminophen (Tylenol), fluoxetine (Prozac), and gemfibrozil (Lopid).

Even though PPCPs are generally detected at low concentrations in our waterways, we cannot be sure of their impact on the environment because their effect on non-human organisms is unknown. People are warned for good reason not to take pharmaceuticals without a prescription or in combination with other drugs, because the synergistic effects can be lethal. But what happens to a Chinook salmon that takes a low dose of Lipitor? And what if that Lipitor is mixed with dozens of other unidentified pharmaceuticals in the water? Because of the seemingly low risk to humans and the sheer number of compounds to be studied, research on the environmental fate of PPCPs is limited and regulation is nonexistent.

A recent study by a team of researchers from Eötvös Loránd University in Budapest and the China University of Geosciences suggests that the risk of residual PPCP exposure to humans may be greater than we think. In some parts of the world, where groundwater supplies must stretched to meet the demand for potable water, riverbank infiltration is seen as a safe and practical method to speed up the recharge of an aquifer. Instead of harvesting drinking water directly from the river, where a wastewater outfall may discharge treated effluent just upstream, water is pumped from wells adjacent to the riverbank, which lowers the water table, changes the pressure gradient, and pulls water from the river into the aquifer. Riverbank infiltration uses the soils of the bank to filter out pathogens, heavy metals, excess nutrients, hydrocarbons, and other pollutants in the same way that stormwater is purified as it naturally percolates through soil; however, with riverbank infiltration this process happens quickly enough to meet the population's needs. Budapest supplies one third of its groundwater through riverbank infiltration of the Danube River, which also receives effluent from two wastewater treatment plants.

Over the course of a full year, Margit Varga and her team sampled water from the Danube River and sediments from within two meters of the bank at three sites adjacent to riverbank infiltration wells. Many PPCP compounds are removed from water when they stick to sediments; however, the research group tested their samples for the presence of four acidic drugs, which have a greater affinity for water and are less likely to grab onto the particles of soil. Three of these drugs - ibuprofen, naproxen, and diclofenac - were regularly detected in the river water. The highest concentrations occurred during the winter when the water level was relatively low and cold temperatures restricted microbial activity that could degrade the compounds. Naproxen and diclofenac were also detected in the sediment samples, suggesting that some amount of these acidic drugs are removed from the water during riverbank infiltration.

The concentration of these drugs in the sediment seemed to be influenced not only by their initial concentration in the water being pulled through the bank, but also by the concentration of total organic carbon in the sediment. Sediment with a high concentration of carbon was more effective at filtering out the drug compounds. Sandy sediment with low carbon content could allow PPCPs to penetrate further into the bank. It is well-known that sediments have different compositions and different abilities to filter out contaminants - this concept has been applied countless times to septic systems and stormwater treatment mechanisms. But Varga's study confirms that the same is true for PPCPs, which are unregulated, poorly understood, and still in the vague category of "contaminants of emerging concern." Given the right combination of low water levels, cold temperatures, increased use of PPCPs, and poor sediment filtration capacity, these compounds could very likely reach drinking water supplies in areas that depend on riverbank infiltration. And as growing demand for potable water brings human populations closer and closer to their treated (or untreated) wastewater, the only way to eliminate the risk of exposure might be the remove PPCPs from the waste stream entirely before they can reach the environment.

Varga, M., Dobor, J., Helenkar, A., Jurecska, L., Yao, Jun., & Zaray, G. (2010). Investigation of acidic pharmaceuticals in river water and sediment by microwave-assisted extraction and gas chromatography-mass spectrometry Microchemical Journal DOI: 10.1016/j.microc.2010.02.010

Photo courtesy of Carly & Art via Flickr

Species Profile: Bay Pipefish

Interesting fact from Baykeeper's upcoming Winter Newsletter: San Francisco's Seahorses are not limited to those plastered on the walls in the Powell Street BART Station.

What is a Pipefish?
The Bay Pipefish (Sygnathus leptohynchus) is a member of Syngnathidae – a family of fish that includes Seahorses and Sea Dragons. The Bay Pipefish shares many characteristics with its enigmatic cousins, including plates of bony armor, small tubular mouths, cryptic coloration, and secretive behavior. Like other Pipefish, however, the Bay Pipefish has a long, straight body.

What do they look like?
The Bay Pipefish is a long, thin fish that grows to about a foot in length. Its coloration varies between shades of green and brown. It may be possible that the Bay Pipefish changes its color to match its surroundings, but this is not known for sure. Just like Seahorses and Sea Dragons, the Bay Pipefish has a long tubular mouth formed by fused jaw-bones.


Where are Bay Pipefish found?
The Bay Pipefish inhabits eelgrass beds and shallow estuaries along the Pacific Coast from Baja California to Alaska. Hidden among blades of eelgrass, the long slender fish is almost completely concealed. The eelgrass beds also support an abundance of prey, allowing the Bay Pipefish to thrive. In the Bay Area, the Bay Pipefish can be spotted in eelgrass beds in San Francisco Bay, Suisun Bay, Drakes Estero, and Tomales Bay.

What do they eat?
The Bay Pipefish uses its tubular mouth to suck plankton prey out of the water like a vacuum cleaner, rather than biting it. When it is hunting, the Bay Pipefish remains completely still beneath its prey. Its eyes are capable of binocular vision, allowing it to determine the distance to its prey. When the position is just right, the Bay Pipefish will quickly snap its head up, placing its tiny mouth about an inch from the prey and delivering suction to capture its meal.

How do they reproduce?
Bay Pipefish reproduction begins in the early spring when eelgrass grows and plankton density increases in the water column. Like other male Syngnathids, the male Pipefish has a well-developed brood pouch on the underside of its tail. After the female deposits her eggs within the male's brood pouch, a layer of tissue grows to seal the eggs inside. The male Pipefish carries the embryos for several weeks, providing them with the nutrients, oxygen, and water they need to develop. When ready to hatch, hundreds of Pipefish young split the pouch and emerge into the water, resembling miniature versions of the adults.

What are the threats to Bay Pipefish in the Bay?
The greatest potential threat to the Bay Pipefish in the Bay Area would be the loss of habitat. Luckily for the Bay Pipefish and other eelgrass dependent species, the extent of eelgrass beds in the San Francisco Bay has actually been expanding in recent years. Although there is no commercial fishery for Pipefish species, they are collected for the Chinese medicine trade. At this time Pipefish are abundant, but if the demand for Pipefish by alternative health care markets increases, Pipefish might become as scarce as their Seahorse relatives.

Photo credit: Aquarium of the Bay

End of a Dynasty: The Loss of the King Salmon

The river canyons, where the old bars were located, were romantic places previous to being disturbed and torn up by the gold-digger. The water was as clear as crystal, and above each ripple or rapid place was a long, deep pool, with water as blue as turquoise, swarming with fish. Salmon at that time ran up all the streams as far as they could get, until some perpendicular barrier which they could not leap prevented further progress.
Angel M. History of Placer County, California. 1882.

The Central Valley Chinook Salmon (Oncorhynchus tshawytscha), also known as the King Salmon, is one of the most iconic species of the Bay Area. In four seasonal runs, the Chinook salmon used to slam the rivers of the Central Valley Basin to spawn in the cold, well-oxygenated water draining from the Cascades and the Sierra Nevada. Every winter, spring, fall, and late-fall these anadramous fish would return from the Pacific Ocean, charging through the San Francisco Bay in numbers reaching the hundreds of thousands. As the largest of all salmon species, with adults often exceeding 40 pounds, the Chinook are important for commercial and recreational anglers alike, supporting the billion dollar California fishing industry. Since the era of California dam building, however, the Chinook populations have plummeted. All four runs have been listed under the Federal and State Endangered Species Acts. Even with hatchery stocks augmenting the wild population, the commercial salmon fishing season had to be closed this year for the second year in a row in order to protect the once robust fall run. The staggering decline of the Chinook spells both ecological and economic ruin for Northern California. Last year's closure of the salmon fishing season amounted to a loss of $255 million and 2,263 jobs.

While some of the salmon runs were nearly extirpated by dam installation in Central Valley Rivers, the unique life history of the fall run allowed it to persist as the backbone of the West Coast fishery for many years. The fall run spends less time in rivers than the other runs, so it is less impacted by land based activities. Also, it tends to spawn downstream of the other runs, so its passage is not blocked by the upstream dams. In recent history, the fall run population had been fairly stable, even experiencing a huge increase in 2000. Despite the large numbers of fish returning to spawn, the fall Chinook run was not as strong as it appeared. In fact, it was on the verge of an unexpected collapse. The fall run experienced record low returns in 2007, prompting the closure of the fishing season in 2008. Even when the fishery was closed, only 66,000 salmon returned to spawn.

Fisheries biologists believed that most, if not all, of the fall salmon returning to spawn came from the hatchery stock. Salmon hatcheries were originally established as part of a compromise between the fishing industry and California energy interests to sustain salmon populations that would be hindered by dam construction. However, the hatcheries have done more harm than good. The addition of a hatchery stock creates the illusion of a robust wild population, even though the wild population is no longer self-sustaining. In fact, the hatchery stocks have reduced the vitality and resilience of the wild population.

But how did the fall run, augmented by hatchery-borne fish, collapse? At the 2009 State of the Estuary Conference, Steve Lindley of NOAA explained how fisheries biologists were able to solve this mystery. Knowing the salmon’s age of sexual maturity, fish that should have been returning to spawn in 2007 and 2008 are from the broods that hatched in 2004 and 2005. Spawning of the wild population and the hatchery population was normal in those years, but survival rates between the broods’ departure from the estuary and their return to spawn were terrible. Therefore the secret to the broods’ failure lies in the environmental conditions they encountered in their three years at sea.

In 2005 and 2006 the water off the California coast was unusually warm. The spring upwelling, which is usually activated by shifting winds to deliver cold, nutrient-rich waters to the surface, had a late start in 2006. As a result, the Chinook salmons’ typical prey species struggled, while anchovies, a fish too large for the young salmon to eat, thrived. The Farallon Islands population of the Cassin’s Auklet, a seabird with the same diet as the Chinook salmon, completely failed to reproduce in 2005. The struggle of the Cassin’s Auklet population should have been a warning sign for salmon returns. Without a reliable food source, the 2004 and 2005 salmon broods suffered in the ocean, unbeknownst to biologists and fishermen until their poor returns in subsequent years.

Even though Delta water management and land-based activities impact Chinook salmon populations indirectly, the proximate cause of the fall run’s most recent collapse was simply a lack of adequate prey. Poor feeing conditions, often driven by natural climate variability, are in no way unprecedented, but the Chinook salmon was not resilient enough to overcome this challenge. Wild fish populations maintain their resilience by having a high degree of biocomplexity, described by Steve Lindley as a portfolio of environmental conditions, such as habitat and prey, which can satisfy the animals’ requirements. If the different runs, including those differentiated by spawning site as well as time, exhibit a diversity of life history patterns, the population as a whole is not intensely impacted by a shift in environmental conditions. In the case of the Central Valley Chinook, however, hatchery stocks have diluted the biocomplexity of the population, so that all the animals exhibit similar life history patterns. Whereas historically there was variability across the runs, today the reliance on hatchery production has pruned back the life history diversity of the Chinook salmon, making the population more prone to booms and busts.

Unfortunately the management strategy of the Central Valley Chinook salmon must rely on hatchery stocks to produce numbers of salmon great enough to sustain the fishing industry. When the salmon returns are poor, managers increase hatchery production, causing overall fitness of the population to decline. But even when the returns are great enough to reopen the fishing season, the apparent strength of the population is merely an illusion. When environmental conditions are favorable, the Chinook population appears to thrive, but the success of the hatchery stock makes it nearly impossible to detect inevitable declines in the wild population. When environmental conditions shift again, the homogeneous population will be vulnerable to another devastating crash.

Decades of hatchery-dependent management of the Chinook has produced a population that is unreliable for the fishing industry and deleterious to the recovery of wild stocks. Even if the fishing season is re-opened for 2010, the idea that a large number of salmon reflects the strength of the population is a dangerous misconception. To ensure long-term viability of the Central Valley Chinook as a species, something must change in order to improve wild salmon production. While there are management options, including brood stock selection and more variability in the timing of hatchery stock release, the best way to improve the fitness of the wild stock is to eliminate the hatcheries entirely. Without hatcheries, however, the wild population may never return in numbers great enough to harvest. Even though the small wild population could regain some of its biocomplexity and vitality, salmon fishing would have to end altogether, an admission of the failure of hatchery-dependent management. It is likely that Californians will have to mourn the end of their famed Chinook fishery in order to celebrate the survival of the species.

Photo: Late-fall Chinook salmon spawning, courtesy of USFWS

Lindley, Steve. 2009. The Once and Future Kings. Presented at the State of the Estuary Conference. Oakland, CA.

Yoshiyama, Ronald M., Eric R. Gerstung, Frank W. Fisher, and Peter B. Moyle. Historical and Present Distribution of Chinook Salmon in the Central Valley Drainage of California. Contributions to the Biology of Central Valley Salmonids. Fish Bulletin 179: Volume One.

Species Profile: Leopard Shark

Interested in San Francisco Bay wildlife? This is a species profile that I wrote on Triakis semifasciata, the Leopard Shark, for our Fall 2009 newsletter. This is the original, soon to be hacked away by the cruel hand of the redactor.

Where are Leopard Sharks found?
Leopard Sharks are found along the Pacific Coast - from Central Mexico to Oregon. One of the most common sharks in California, there is a large population of Leopard Sharks living in the San Francisco Bay. Most of them live in the Bay year round, with a few individuals migrating out in the fall. Leopard Sharks are often spotted near the bottom in the shallow waters of the sloughs and mudflats along the Bay margins. The Bay offers a safe haven for the Leopard Shark, because the water is too shallow and warm for predators, such as the Great White Shark. Plus the Leopard Shark finds abundant prey in the muddy bottom of the Bay. They often follow the high tide up to the shoreline to feed on animals in the shallow mudflats; then they move back out as the water recedes.

What do they look like?
The Leopard Shark is a slender fish with silvery-bronze skin and dark ovals arranged in neat rows across its back. Leopard Sharks are quite small. Their average length is around three to four feet, although they can grow up to seven feet. The Leopard Sharks in San Francisco Bay are more likely to be between two and three feet long.

What do they eat?
Leopard Sharks feast on small invertebrates, such as clams, worms and crabs that they find along the muddy bottom of the Bay. They also like small fish, eggs and the occasional Bat Ray. Sometimes the Leopard Shark can pluck prey right off the mud with its bottom-facing mouth. In other instances, the shark will shovel its nose into the bottom and toss the sediment away, exposing hidden clams or worms. Leopard Sharks may go to extreme lengths to eat small animals, but they will not attack humans.

How do they reproduce?
Leopard Sharks have ovoviviparous reproduction, which means that the baby sharks, or pups, develop in eggs that are retained within the mother’s body. The eggs hatch in the mother’s body, and then the pups are born live. A female Leopard Shark can have up to 29 pups in one litter.

What are the threats to Leopard Sharks in San Francisco Bay?
Leopard Sharks are fished both commercially and recreationally, with recreational fishing accounting for the majority of the catch. Even though it is an abundant species, Leopard Sharks grow so slowly that overfishing could deplete the population. Concerns about overfishing lead to the implementation of size limits by the Department of Fish and Game - Leopard Sharks smaller than 36 inches must be released. Leopard Sharks also contain high levels of mercury in their tissues. These animals have a greater exposure to mercury than other fish species because they spend so much time feeding in contaminated Bay sediments. It is unknown if the mercury is harmful to the Leopard Sharks, but it certainly exceeds the accepted safe limit for humans.

Photo credit: Peter J. Bryant

Hospitality Returning to the Bottom of the Bay

We must consider many factors before settling our lives into a new place. Whether it is the school system, safety or convenience of transportation, people have a list of requirements for their suitable habitat. It is the services and infrastructure after all that distinguish our comfortable communities from hard life on the frontier. Whether dispersing from their population or remaining exactly where they were born, organisms seek to fill similar needs when settling into their habitat. Some plants and animals, known as foundation species, are specially equipped to satisfy these requirements for many different species. By virtue of their physical characteristics, foundation species provide three-dimensional habitat for entire ecological communities, and in doing so dramatically enhance biodiversity in a relatively small area. Reef-building organisms like corals and oysters, trees that form a dense canopy layer, and the impenetrable underwater forests of kelp are all examples of foundation species that host robust ecosystems.

As we have learned from the worldwide destruction of coral reefs, declines in foundation species pose an enormous threat to their associated, denizen species. For the same reason, the protection and restoration of foundation species could be the most important step to maximize the conservation of global biodiversity. This conservation strategy is currently underway in San Francisco Bay, as collaborative effort between Audubon California, Save the Bay, NOAA, and San Francisco State University strives to restore and enhance one of the most important foundation species in San Francisco Bay – Zostera marina, or eelgrass.

Eelgrass is a type of seagrass – a marine flowering plant (not a seaweed!) that grows submerged in shallow water areas worldwide. Seagrasses form vast meadows in coastal environments that resemble terrestrial grasslands, their dense root system and tall leaf canopy creating complex habitat in areas that are otherwise unvegetated. Seagrass beds provide food, cover, and spawning ground for a wide array of invertebrates, fishes, birds, and mammals. Found in tropical as well as temperate regions, seagrasses play host to hundreds of associated species including green sea turtles, manatees, seahorses, and countless species of fish. As a biodiversity hotspot, seagrass beds also attract hordes of predators that come to feed on their residents. Unfortunately, seagrasses are declining worldwide at an astounding rate. Like all foundation species, the destruction of seagrasses can have severe impacts on the many associated species that rely on seagrass bed habitat. A recent study by A. Randall Hughes of UC Davis found that nearly 15% of all seagrass species worldwide are currently listed as threatened in some portion of their range. For every species of seagrass, there is at least one associated species of concern, and in total there are 74 species of concern that are associated with seagrasses worldwide. These results come from a preliminary study, however, and the true conservation costs of seagrass declines have likely been underestimated. Moreover, there is a general lack of awareness of the importance of seagrass bed ecosystems on biodiversity.

Over the past few decades within the San Francisco Bay, the size and number of eelgrass beds has been steadily declining, mostly due to reduced light availability. Like all plants, eelgrass requires sunlight for photosynthesis; however, conditions within the Bay have severely limited the depth to which light can penetrate the Bay water. Dredging operations in the Bay destroy eelgrass beds either by physical disturbance or by stirring up sediments to increase turbidity. Construction activities in the Bay watershed release sediments to streams that eventually reach the Bay, smothering eelgrass beds. Even if there is enough light for the plants to growth, excess nutrients can accelerate algae growth beyond the feeding rates of grazers, allowing the algae to over take eelgrass leaves and block out light.

Biologists of the eelgrass restoration team are putting in a great effort to enhance existing eelgrass beds and restore this habitat to the fullest extent of its San Francisco Bay range. Richardson Bay in North San Francisco Bay is the ideal location for eelgrass restoration. It harbors the second largest eelgrass bed in the estuary, with plants that have the greatest genetic diversity of all beds sampled. Given its sheltered location and distance from dredging operations, Richardson Bay has the model environmental conditions for large eelgrass beds, but the genetic diversity of its plants also gives hope for successful transplanting to other sites in the Bay. Using a variety of techniques, biologists are hoping to discover the restoration method with the highest success rate. Both mature plants and seedlings are transplanted to sites at four different depths where they are either hand-planted by divers or tied to special grid-like frames which sink to the muddy bottom. At the same time the team is modeling Bay circulation patterns to better understand the potential for seed dispersal from existing beds. Divers are collecting mature eelgrass flowers from donor beds and using them for targeted seed dispersal at other sites in the Bay. Seeds can be deployed either by hand or from mesh bags attached to buoys which hold the flowers and distribute the seeds in a circular pattern, moving with the current.

The restoration team and Bay Area naturalists alike hope that these efforts will reverse the Bay’s long-term decline in native biodiversity, giving us an example of the multi-layered ecosystem that this foundation species once supported. At the base of its complex food web, dense mats of eelgrass roots hold sediments in place and keep them well-oxygenated to support the growth of important bacteria. Eelgrass leaves provide substrate for algae and epiphytic plants which are grazed upon by a number of invertebrates. Even dead eelgrass plants that settle within the bed, develop a film of bacteria, fungus and detritus, which also feeds small invertebrates. During low tides, eelgrass beds hold moisture, so that these small organisms are protected. As a result, waterfowl arrive in droves to feast on a surfeit of invertebrate prey. The Pacific Herring, the largest commercial fishery in the Bay which has seen recent population declines, depends on eelgrass beds for spawning and cover. The herring lay their sticky eggs on eelgrass leaves so that the young will be protected until they reach maturity. The success of these restoration efforts could enhance the Pacific herring population, allowing for increased takes by local fishermen. Birders would also be happy to see the return of the diversity of native and migratory waterfowl that hunt the in eelgrass beds. To learn more about the progress of the San Francisco Bay eelgrass restoration, visit www.tiburonaudubon.org

Cited: Hughes, A. Randall, Susan L. Williams, Carlos M. Duarte, Kenneth L. Heck Jr., and Michelle Waycott. 2009. Associations of concern: declining seagrasses and threatened dependent species. Frontiers in Ecology and the Environment. 7:242-246

Photo credit: www.ceoe.udel.edu

The Green Sturgeon's Dangerous Diet

The enigmatic Green Sturgeon (Acipenser medirostris) patrols the benthos of the San Francisco Bay and near shore oceanic waters as a living relic of ancient seas. This large, long-lived fish species, which has persisted for millennia in evolving oceans, may have finally met its match in the environmental impacts of Bay Area development. The Southern Distinct Population Segment (DPS) of the Green Sturgeon, which is listed as threatened under the federal Endangered Species Act, swims through the San Francisco Bay to reach its only remaining spawning ground in the Sacramento River. As these animals swim through the Bay and Delta, they face deteriorating water quality, reduction of freshwater flows, potential poaching for caviar or bycatch in other fisheries, entrainment in water intake structures, and impassable upstream barriers. The principle threat to the Southern DPS is the disappearance of its spawning ground. Now restricted to a very narrow stretch of the Sacramento River, the elimination of the remaining spawning ground would mean the extinction of this genetically distinct Green Sturgeon population. The National Marine Fisheries Services (NMFS) is strengthening protective measures of the Southern DPS by proposing the same take prohibitions that are applied to species listed as endangered. Take prohibitions will make it illegal to hunt, harass, or otherwise harm the fish, including any action that degrades its critical habitat.

Unfortunately this step may not be enough to ensure the long-term survival of the population. A combination of human-influenced factors, now woven into the ecological fabric of the San Francisco Bay and Delta, has turned this estuary into a toxic environment where animals are actually poisoned by their food web. The Green Sturgeon feeds on invertebrates that it finds bottom of the Bay, including the invasive Overbite Clam (Potamocorbula amurensis). This prolific bivalve, which can be found in densities as great as 50,000 per square meter in some areas of San Francisco Bay, is likely to compose the better portion of the Green Sturgeon’s diet. The Overbite Clam itself has a voracious appetite, and it rapidly filters food particles out of the water column with amazing efficiency. Although it may be seeking tiny organisms and detritus, the clam inadvertently consumes the contaminants that pollute the water column including selenium, a bioaccumulative element that comes from oil refineries and Central Valley agriculture. The efficiency with which it incorporates selenium into its tissues makes the Overbite Clam a toxic meal for any predator it succumbs to.

The impact of selenium may not be immediately apparent in the individual adult fish, but it can cause massive reproductive failure. Selenium from a diet of contaminated Overbite Clams will bioaccumulate in fish tissues over the course of its lifetime. Although it may not harm the adult fish, selenium is transferred from a female fish to her eggs, which can cause embryonic death or fatal deformities upon hatching. These reproductive impacts can be severe enough to devastate a population. All fish species in the San Francisco Bay that feed on the Overbite Clam are at risk; however, the unique life history of the Green Sturgeon makes it more vulnerable to this poisonous prey.

In many ways the life of the Green Sturgeon is similar to that of a human. It has a remarkably long lifespan of up to 70 years, and it does not reach sexual maturity until it is at least 15 years old. As an adult it has an iteroparous reproductive strategy, meaning it allocates energy to multiple spawning efforts over the course of its lifetime as opposed to a “big bang” spawning effort once before death. The Southern DPS of the Green Sturgeon, which spends the majority of its adult life in the ocean, returns to the Sacramento River every 2 to 5 years to spawn. Even though it spends more time in the ocean than other sturgeon species, Southern DPS adults may live in the estuary for seven months of the year and juveniles can live here year-round, all the while exposed to dietary selenium.

Given its late age of sexual maturity, the Green Sturgeon will accumulate selenium in its body for at least fifteen years before it first spawns. The level of bioaccumulated selenium imparted to eggs will then increase for all subsequent reproductive efforts as the sturgeon ages. As a result the reproductive impacts of selenium are likely to be more severe for the Green Sturgeon than for a fish with a shorter lifespan and quicker maturation. This reproductive challenge can greatly reduce recruitment within the Southern DPS, meaning that fewer individuals are surviving to reproduce and maintain the size of the population. With this obstacle to the population’s survival so deeply rooted in the ecology of the San Francisco Bay and Delta, the actions that result in the take of an individual animal seem relatively easy to avoid. The proposed take prohibitions are a necessary step in slowing the decline of the Southern DPS, but they are by no means the solution. The elimination of selenium discharges to the San Francisco Bay and Delta may be the only way to ensure the population’s long-term survival.

(Photo credit: David Gotschall)

After 150 Years - Clarity and Consequences

Earlier this spring during a spate of unusually hot weather in the Bay Area, rays of sunlight stretched below the surface of Richardson Bay to trigger an intense algal bloom. Like all blooms, this rapid proliferation of algae was encouraged by the warm temperatures and an adequate supply of nutrients. About a month later another bloom occurred. Both events resulted in floating clumps of innocuous red algae and calls to the Baykeeper pollution incident hotline from concerned shoreline residents. My response: Don’t panic. If it doesn’t smell, it’s not a sewage spill.

According to an article by James Cloern, et al in the 2006 Pulse of the Estuary, Bay Area residents should become familiar with this sight. Algal blooms have been occurring with increasing frequency in the San Francisco Bay since the late 1990s, and the trend is likely to continue. The cause has been uncertain, however, because a host of factors promote the growth of algae. These include predators, nutrients supply, temperature, and metals. In every ecosystem one of these variables must be the limiting factor that controls algae growth and prevents bloom events. In many aquatic systems, such as the Chesapeake Bay, nutrients are the limiting factor. Given the excessive agricultural runoff in the Chesapeake Bay watershed, it is no surprise that algal blooms have been a serious problem. Despite the always reliable winter sewage spills, however, nutrient levels in the San Francisco Bay have been consistently low. So what is the variable that allows this unusual and unseasonable growth of algae? The upcoming 2009 issue of the Pulse of the Estuary will shed more light onto this question. The answer, in fact, is light.

The San Francisco Bay is becoming clearer! The concentration of suspended sediment in the Bay has been steadily decreasing since 1999, allowing sunlight to reach further below the surface of the water, stimulating algae growth and causing blooms. Incredibly, the reason for our water clarity today stems from human activities during the Gold Rush Era. In the late 1800s hydraulic gold mining sent tons of sediment, waste from the search for gold in the Sierra foothills and the Coast Range, down the Sacramento River and other Central Valley rivers. At the same time, development in the Bay Area caused the erosion of stream banks. Shoreline tidal marshes that were diked off to increase buildable and farmable land area could no longer capture this eroded sediment at the shore before reaching open water. As a result, the sediment settled on the floor of the Bay – so much sediment in fact, that the Bay became shallower. Bay Area residents are very familiar with the dredging platforms that regularly remove sediment, carving navigation channels into the floor of the Bay. In addition to dredging, natural wave patterns and burrowing wildlife can stir up sediment and re-suspend it in the water column. High concentrations of suspended sediment reduce the depth to which sunlight can penetrate the water, thus controlling algae growth and preventing most blooms.

Recent USGS data suggest that the Bay experienced a dramatic increase in clarity when this erodible supply of sediment was depleted in the late 1990s. In this year’s Pulse of the Estuary, David Schoellhammer of USGS offers an explanation as to how this may have happened. As long as the San Francisco Bay received sediment from upstream sources and held suspended sediment at capacity, erosion from the floor of the Bay was minimal. Although the Sacramento River delivered sediment, it also gently flushes the Bay and gradually pushed sediment through the Golden Gate. River banks in the Central Valley were protected during the 1900s to prevent erosion, and other sources of sediment are trapped behind dams. The remainder of the hydraulic mining supply slowly moved downstream until it reached the Bay. As a result the Sacramento River delivered clear water, which increased the erosion of sediment on the Bay floor. In 1998, a wet year during which the strong, clear flows from the Sacramento River persisted well into the summer, most of the remaining sediment supply was likely eroded pushed out of the Bay. The following year saw the suspended sediment concentration of the Bay waters decrease by 50%.

This great sweep of sediment through the Golden Gate did not unearth an ecological time capsule to the Bay’s pre-Gold Rush condition. The subsequent increase in clarity in the Bay is a major shift in water quality, which is causing a cascade of ecological and economic consequences in light of modern environmental stressors. As Bay Area residents have recently witnessed, the low concentration of suspended sediment in the Bay makes more light available to stimulate the growth of photosynthetic organisms – aquatic plants, algae, and other phytoplankton. As these organisms thrive they feed higher trophic levels, and the Bay food web becomes more robust. As Schoellhamer points out, the San Francisco Bay has crossed a threshold and become an estuary with a level of primary production that is more typical of temperate latitudes. This increased productivity has implications of its own. With a greater availability of light, nutrient inputs have a greater impact in the growth of algae. While the San Francisco Bay regularly receives nutrients from agricultural runoff or sewage spills, the low light has always prevented excessive growth of phytoplankton. Under current conditions, however, these inputs may trigger more intense bloom events and their associated problems.

The loss of sediments may also hinder coastal wetland restoration efforts. Wetland restoration usually involves opening up a previously diked area to the tides, so that suspended sediments in the water will naturally settle out along the shore, gradually building up until the land is high enough for plants to colonize. The lower the concentration of suspended sediments in the water, the longer it will take for the wetland to develop. Now with rising sea levels threatening to inundate our shorelines, the growth of new wetlands will likely be outpaced. To speed up the process, wetlands restoration projects may also utilize dredge spoils. With the loss of sediment from the Bay bottom, however, there is less of a need for dredging and a limit to sediment available for these restoration projects. Incredibly, the natural expulsion of sediments from the Bay, which caused supplies to shrink while demand has recently grown, has changed hidden Gold Rush waste into a valuable natural resource.

Learn more about Bay sediment in the 2009 Pulse of the Estuary, from the San Francisco Estuary Institute. The Pulse is the annual report for water quality in San Francisco Bay. You can find it at www.sfei.org

(Photo Credit: Michael Slater 2006)