Coral Smothering "Green Tide" Seaweed Spreading on Florida Reefs
According to recent reports from divers and fishers, the coral-smothering, non-native seaweed known as Caulerpa brachypus has now become so thick on reefs in Florida's Palm Beach County, about an hour north of Miami, that it is forcing lobsters and fish away. The species has also now been spotted as far north as Ft. Pierce, Fla., approximately 60 miles away.
"It can smother just about everything down there," says Dr. Brian Lapointe, a marine ecologist at Harbor Branch, Fla. He says the threat it poses is even more alarming than that of other troublesome species he has studied in the area because it is an invasive normally found in the Pacific, and, until a year ago, nowhere in Florida. The species was probably inadvertently released from a saltwater aquarium or from a ship's ballast water. Because it is not native to Florida waters, it has no natural predators, a problem compounded by the fact that the species is especially rugged and able to spread quickly if the nutrients it needs are available. "It can really undergo explosive growth," says Lapointe.
Based on past research, Lapointe believes that the spread of this and other macroalgae species, in Florida and at many troubled reefs around the globe, is driven by nutrients from land-based pollution. In South Florida, one of several key sources of such pollution is hundreds of millions of gallons of nutrient-rich, secondarily-treated sewage regularly pumped offshore each day.
Caulerpa brachypus's explosive growth devastates reefs. Besides smothering and killing the coral itself, it covers over the food on which many fish rely, forcing them and their predators away from a reef; and, among other problems, it can fill in the ledges and crannies that attract lobster. Despite this destructive capacity and the potential for serious economic impact, there is currently no scientific information available about how fast the species is spreading or even how much area it currently covers in Florida.
Lapointe and his colleagues discovered the seaweed for the first time in Florida waters about a year ago. At that time they found it had already covered acres of reef. Florida's 2002 budget, as approved by the state legislature, had included roughly half a million dollars for Lapointe's team to study the macroalgae problem, but this funding was later eliminated by a line-item veto. Consequently, C. brachypus's spread has so far not been studied in any way.
But Lapointe has now received a grant through EPA's national Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) initiative that will allow such work to move forward.
Over the next two years, Lapointe and his colleagues will complete a comprehensive study of the factors controlling the spread of Caulerpa brachypus and two other problematic seaweed, or macroalgae, species. Lapointe predicts that the spread of macroalgae on Florida reefs, sometimes referred to as a "green tide," will have devastating ecological and economic impacts unless controlled. His work should lead to forecasts for the amount of damage to expect from macroalgae in coming years as well as provide information about how best to control or prevent its spread.
Lapointe and his team will conduct quarterly surveys of these sites, as well as laboratory experiments, to determine how seasonal changes in light, temperature and nutrient availability control the growth and spread of harmful macroalgae. They will also determine whether growth is seasonal or year-round -- a key factor in determining how fast it spreads.
To test his hypothesis that nutrients from pollution are fueling macroalgae blooms in the area, Lapointe and his colleagues will be comparing how well each species grows when nitrogen in the form found in sewage is available versus how it responds to nitrogen as it occurs naturally in seawater. They will also analyze the chemical signature of macroalgae samples for evidence of which type of nitrogen is driving growth.
In addition, the team will measure the way the macroalgae species reflects light to establish a method for measuring the extent of macroalgae spread in Florida and around the globe using remote sensing from satellites or airplanes.
Lapointe says it is critical that leaders take the threat from the Caulerpa brachypus seriously, and points to other regions that have faced similar problems as examples of why. In the Mediterranean, for instance, government officials essentially ignored the problem when Caulerpa brachypus's cousin, Caulerpa taxifolia, was first found there until it was too late to control. Thousands upon thousands of acres of reef have now been destroyed and billions of dollars worth of damage done.
For more information, please visit www.hboi.edu/index_06.html.
Scientists Discover Medical Drug Resource in Deep Ocean Sediments
Although the oceans cover 70 percent of the planet's surface, much of their biomedical potential has gone largely unexplored, until now.
A group of researchers at Scripps Institution of Oceanography at the University of California, San Diego, have for the first time shown that sediments in the deep ocean are a significant biomedical resource for microbes that produce antibiotic molecules.
In a series of two papers, a group led by William Fenical, director of the Center for Marine Biotechnology and Biomedicine (CMBB) at Scripps Institution, has reported the discovery of a novel group of bacteria found to produce molecules with potential in the treatment of infectious diseases and cancer.
The first paper, published in the October 2002 issue of Applied and Environmental Microbiology, highlights the discovery of new bacteria, called actinomycetes, from ocean sediments. For more than 45 years, terrestrial actinomycetes were the foundation of the pharmaceutical industry because of their ability to produce natural antibiotics, including important drugs such as streptomycin, actinomycin and vancomycin. The data from this paper provides the first conclusive evidence of the widespread occurrence of indigenous actinomycete populations in marine sediments.
The second paper, published in the Jan. 20, 2003, issue of the international edition of the chemistry journal Angewandte Chemie, identifies the structure of a new natural product, which Fenical's group has named Salinosporamide A, from this new bacterial resource. The new compound is a potent inhibitor of cancer growth, including human colon carcinoma, non-small cell lung cancer and, most effectively, breast cancer. January's report cracks the door open for a line of similar discoveries from the recently discovered Salinospora genus.
Although more than 100 drugs today exist from terrestrial microorganisms, including penicillin, arguably the most important drug in medicine, the potential from land-based microbial sources began dwindling nearly 10 years ago. Pharmaceutical investigators searched high and low around the globe for new terrestrial, drug-producing microbes, but with diminishing payback. According to Fenical, when considering the ever-increasing resistance of bacteria to existing antibiotics, the need to make new discoveries becomes essential.
Surprisingly, the oceans, with some of the most diverse ecosystems on the planet, were largely ignored as a potential source for actinomycete bacteria. Given this omission, it was natural for Fenical's group at the Scripps CMBB to initiate studies of marine environments for new microorganisms important in pharmaceutical discovery.
His group developed new methods and tools for obtaining a variety of ocean sediments, including a miniaturized sampling device that efficiently captures samples from the deep ocean. They derived bottom muds from more than 1,000 meters deep from the Atlantic and Pacific Oceans, the Red Sea and the Gulf of California. They also developed new methods for sifting through these samples (which contain roughly one billion microorganisms per cubic centimeter), culturing the microorganisms, identifying them by genetic methods and screening their metabolic products for anticancer and antibiotic properties.
The results from their biomedical studies were extraordinarily positive. Of 100 strains of these organisms tested, 80 percent produced molecules that inhibit cancer cell growth. Roughly 35 percent revealed the ability to kill pathogenic bacteria and fungi. Based on the worldwide distribution of Salinospora, Fenical estimates that many thousands of strains will be available.
In addition to Fenical, coauthors on the papers include Tracy Mincer, Paul Jensen, Christopher Kauffman, Robert Feling, and Greg Buchanan.
For more info, visit scrippsnews.ucsd.edu.
Scientists Test Shallow Marine Systems' Response to Increased Nutrients
Most of the efforts to determine how estuaries respond to nutrient enrichment have been confined to relatively deeper and/or muddier river mouth estuaries. However, much of the Atlantic coast from Cape Cod to Cape Fear, as well as parts of the Florida coast and almost all of the Gulf Coast is characterized by a different type of coastal system, called by various names including lagoon, inland bay and salt pond. These more complex shallow systems are now facing increasing nutrient enrichment from agriculture and suburban housing development with associated onsite sewage disposal systems and groundwater nitrogen enrichment.
A team of scientists at the University of Rhode Island (URI) Graduate School of Oceanography (GSO) have focused their research on these very shallow lagoon-type estuaries to determine if there are predictable patterns of response to nutrient enrichment in these more complex systems. The research team includes biological oceanographer Dr. Scott Nixon, research associates Betty Buckley and Steven Granger, and recent PhD graduate Joanne Bintz.
According to a recent article in the journal Human and Ecological Risk Assessment, the scientific team summarized data from 30 systems with mean depths ranging from one foot to 12 feet and water residence times from 0.3 days to 100 days. In addition, the team designed and built a coastal lagoon mesocosm facility where they replicated and controlled nutrient inputs, mixing rates and water resident time. Fed by water from Narragansett Bay, the mesocosms had a variety of typical coastal lagoon organisms added to them, in addition to the plankton that enter with the bay water and the animals contained in the sediment.
While the scientists observed some changes with regard to phytoplankton blooms and the increase of epiphytic algae growing on seagrass leaves, they were most concerned with the impact of nutrient enrichment on the survival and health of eelgrass. The mesocosm experiments showed that the epiphytes appeared to have little or no role in eelgrass survival.
When early and prolonged algal blooms occur due to nutrient enrichment, eelgrass leaves elongate rapidly, but there is little energy put below ground in the development of roots and rhizomes. This may occur, in part, because of the natural shading provided by the algal bloom. But even when the researchers significantly increased the presence of filter feeding mollusks in nitrogen-enriched tanks, and the water of the tanks remained clear, the eelgrass still responded by developing longer leaves and little below-ground material.
Nixon and his team concluded that the development of long leaves at the expense of root and rhizome growth, regardless of whether caused by nutrient enrichment or by shading, means that there will be little or no lateral branching of rhizomes and little or no production of new shoots. As a result, the density of eelgrass beds exposed to nutrient enrichment and/or shading declines over the summer.
The lagoon mesocosms were constructed using funds from the RI Sea Grant Program and the National Oceanic & Atmospheric Administration (NOAA) Coastal Ocean Program. Some of the shallow water indicator experiments were supported by the U.S. Environmental Protection Agency (EPA) and the RI Sea Grant Program.
For more information, please visit www.uri.edu.
Cleaning up Toxic Freeway Runoff the Natural Way
Taking a clever, low-cost and natural approach to the problem, University of California at Los Angeles (UCLA) researchers hope to prevent stormwater runoff from washing thousands of pounds of pollutants into the ocean each time it rains.
When the rain begins to fall in Southern California, the freeways get slippery because the water lifts the oil and grease that has collected on the pavement. The initial cloudburst also breaks loose tons of pollutants, sending them down the storm drains and into the ocean, according to Michael K. Stenstrom, professor of civil and environmental engineering at UCLA's Henry Samueli School of Engineering and Applied Science.
Stenstrom and his team are currently trying to ascertain how much higher the concentration of pollutants is in the first part of the stormwater runoff. If the data supports his theory that the first burst of stormwater contains the most potent concentration of toxins, Stenstrom said, "we have the opportunity for some natural treatment systems."
His goal is to find a way of reducing the amount of pollutants reaching the ocean. He hopes to use the data he is collecting "to save money because there is such a high volume of stormwater that you can't possibly treat it all."
Mixed with the crankcase drippings and partially burned fuels that become polynuclear aeromatic hydrocarbons (PAHs), some of which are carcinogenic, the toxic stew that makes up stormwater runoff also contains heavy metals, such as zinc, copper, nickel and chrome, Stenstrom said. Some of these are the products of automobile corrosion; some comes from brake pads. Stenstrom noted that some PAHs could be found in soot-like, micron-size particles. He cited diesel engines as one of the main sources of these particles.
Because conventional storm drains were designed to prevent flooding, they provide what Stenstrom calls "the biggest, slickest pipe to the ocean." He continues, "if you want to prevent floods, that's the way to do it. Get the water down to the ocean. But when you push it down to the ocean that quickly, you transport all the contaminants along with it."
Instead, Stenstrom said, "Let's try to take some of the water -- as much as we can -- and hold it up on the land, giving the pollutants a chance to be removed and maybe, just maybe, we'll be able to reclaim some of it, too." To accomplish this, Stenstrom advocates constructing bioinfiltration basins along the freeway shoulders. These would consist of a trench about two feet wide and three or four feet deep. It would be filled with gravel and topsoil and covered with some type of grate that allows water to flow freely into the trench. Because the gravel is about 50 percent porous, each cubic yard of gravel can hold a cubic yard of water.
"When it starts to rain, the first really dirty water flows into the bioinfiltration basin, goes down into that gravel and topsoil and it stays there," Stenstrom said. "The rest flows off because the gravel is full." This natural and cost-effective method would collect the first hour's worth of stormwater runoff. In addition to trapping the pollutants, Stenstrom said, this method could detoxify them, as well. If allowed to filter into the soil, the top layer of soil will remove both heavy metals and PAHs, Stenstrom said.
"You can trap them there for many, many years and the PAHs will biodegrade over time," Stenstrom said. "There are organisms that will detoxify PAHs if you just keep them in the soil." Such a method could treat the dirtiest water at the lowest possible cost, Stenstrom said. "We're trying to be clever and save our money and treat the most."
As the water seeps out, the gravel lets in air that promotes the growth of aerobic bacteria, creating an effective, natural treatment system. Heavy metals are absorbed by the soil, where they remain trapped. The soil need not be replaced for at least 20 -- and possibly as long as 50 -- years, Stenstrom said.
Stenstrom said he has become an advocate for the use of bioinfiltration basins to treat stormwater runoff. "I've been pushing this idea," he said. "A lot of what I'm trying to do is convince people in public office."
For more information, please visit www.seas.ucla.edu/stenstro.
Environmental Engineers Tackle Destructive Nutrients in Waterways
Researchers from Tufts University, Medford, Mass., have received two three-year grants from the EPA totaling more than $1.2 million to study how to control the destructive effects of excessive nutrients in waterways -- an environmental problem that threatens aquatic plant and animal life across the country.
"Tufts is a national leader in computer modeling for urban water quality issues," said Steven Chapra, who holds the Louis Berger Chair of Computing and Engineering at Tufts. "These grants will leverage our expertise in developing computer models that will reflect the ways in which nutrients -- such as lawn fertilizer, animal waste and other substances -- enter America's waterways."
The computer models developed by Chapra and his team of Tufts civil and environmental engineers, including Paul Kirshen, Richard Vogel, John Durant and Lin Brown, will help scientists and communities across the country more effectively manage nutrients.
Eutrophication occurs when these nutrients foster excessive growth of plant life in the water, using up oxygen in the water and killing aquatic life. The lack of oxygen also leads to the release of more nutrients, as well as other pollutants from sediments into the water.
The digital modeling tools that the Tufts engineers are developing with colleagues from the Massachusetts Institute of Technology (MIT) and North Carolina State University will help local communities map out watersheds, identify trouble spots and take cost-effective steps to manage the nutrients entering the water. The Tufts team also will develop similar computer models that will be used by EPA and state governments -- improving upon current systems for managing watershed nutrients.
The engineers are using Massachusetts' Mystic and Aberjona Watersheds to design the computer modeling programs but; according to Kirshen, "The technology we've developed will benefit waterways throughout the world." Tufts engineers have installed water-monitoring equipment along the Mystic and Alewife Brook at locations heavily used by recreational boaters and swimmers. In the spring of 2003, data from these sites will be transmitted through radio technology to a central server at Tufts, where information will be processed, archived and placed in publicly accessible venues, such as dial-in phone messages, cable television and Internet Web sites. Color-coded water quality flags will also be placed at key riverfront locations. The Tufts team, and its partners from the city of Somerville, Mass., and the Mystic River Watershed Association, will undertake an aggressive information campaign to let area residents know that this information will be readily available at their fingertips.
For more information, please visit www.tufts.edu.
This article originally appeared in the 05/01/2003 issue of Environmental Protection.