1. Compare and contrast the biodiversity found in today's oceans with what existed in earlier times. Be careful in establishing a "baseline" for comparison: What looks relatively rich today compared with 10 years ago may be a lot less impressive in the context of a 50-year look-back. Do an article for the children's section, introducing "biodiversity in the oceans" as an important counterpart to land-based biodiversity. Feature one or more endangered species native to your area or having broad popular appeal -- such as horseshoe crabs, sharks, or sea turtles. (But don't overlook the vital importance of micro-fauna and other "small critters" and life forms to a sound ecology.) Horseshoe crabs depend on shallow, now largely polluted, bays for reproduction. These creatures' unique set of genetic information has lasted for millions of years. Their rapid disappearance in coastal areas where they thrived only decades ago suggests that extinction may not be far off. Sharks have emerged from virtual pariah status in the minds of some to become trendy fare on menus of posh restaurants. This newfound popularity, combined with their low reproductive rates, threatens their virtual elimination in some coastal areas. Practical sidebars can suggest student field trips, aquarium visits, and other types of hands-on activities.

2. What are scientists in your area and worldwide doing to sample the contents of the oceans? Ask about efforts to "tag" and "track" species so their locations and travels can be recorded. Also, what new technologies, for example, are making it easier for aquariums and researchers to plum the ocean depths and follow the migrations of vital ocean species? Learn what scientists are doing to strengthen and expand the field of marine taxonomy, by which species are identified and labeled. The nonprofit All Species Foundation has set a goal of discovering, identifying and classifying every living species on Earth within a single human generation. "We want to make taxonomy cool," says co-founder Kevin Kelly.

3. Describe ocean trawling and its effects on marine biodiversity. This practice has been compared to forestry clearcutting, but the total area affected by trawling is 150 times greater than the area affected by forest loss. Trawling can benefit species that tolerate disturbance while at the same time harming others. One outcome is that exotic or invasive species can gain a foothold in a new area, in some cases threatening the delicate ecological balance that had existed.

4. Report on and evaluate the pros and cons of various management options to stem the loss of marine biodiversity. What are the strengths and weaknesses of marine protected areas, the seas' counterpart to land-based national parks? What is being done to reduce incidental "bycatch" of non-target species? What are the pros and cons of aquaculture or "fish farms"? How are these areas actually working in practice?

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Biological diversity (often called biodiversity) is a term used to describe the extraordinary variety of life on Earth, from genes, to species, to ecosystems. In the words of E.O. Wilson, the noted Harvard University biologist credited with coining and popularizing the term, it is the "very stuff of life."

Biodiversity as a discipline is considered to have three major focus areas: species diversity, genetic diversity (differences among and within populations), and ecosystems and habitat diversity. "Species" comes from the Latin word for "kind" or "appearance." Taxonomists classify organisms into species on the basis of their physical appearance and potential to interbreed to produce viable, fertile offspring. Species diversity pertains to the total number of species found in a given geographical region.

Genetic diversity refers to the incredible variation within species that allows species to adapt to changes in their environment.

Ecosystem diversity, an emerging discipline, refers to the variety of habitats and communities and the ecological processes driving and defining these communities.

Estimates of total number of terrestrial and marine species on Earth -- including those not yet discovered, so the estimates are obviously just that! -- range from 5 million to 100 million. While they engage in friendly professional rivalry, marine and terrestrial biodiversity experts generally agree, based on numbers of species currently known, that fewer species likely inhabit the oceans than the land. (Conceding this point, some marine biodiversity interests quickly counter that a head-count alone can be misleading, insisting that at the higher taxonomic levels -- class, phylum, and various subdivisions -- marine ecosystems have a higher level of biodiversity.)

Scientists are routinely discovering new families, orders, and even phyla of marine species. Large-scale diversity is readily apparent in even small-scale marine habitats: A small rock from a tropical reef, for example, can easily yield examples of 11 or more phyla.

Just as on land, not all ocean habitats accommodate equal numbers of species. Coral reefs and temperate bays and estuaries, for instance, are believed to contain vast numbers of species that have yet to be described. According to the National Research Council, some inaccessible environments, like polar regions and the deep seas, are so under-sampled that each expedition to a new area yields a wealth of new species discoveries: "Newly recognized biological habitats that contain novel species assemblages -- such as hydrothermal vents, whale carcasses, brine seeps, and wood debris -- continue to emerge, especially in deep water.?"

Unable to place a firm number on the amount of biodiversity that existed to start with, it is of course impossible to say precisely how much has been lost. Estimates of total species in the seas range from a low of 500,000 to a high of 10 million (compared with the 5 million to 100 million for terrestrial and marine species).

Even in circumscribed locations like coral reefs, it's difficult to estimate how many species may be present. "To identify every species in a reef," says biologist John Ogden of the Florida Institute of Oceanography, "you'd have to blow it up, level it, to see what was living in the crevices."

Until just recently, some believed marine organisms might be immune from human-induced extinction. This conviction stemmed in part from the awareness that many sea creatures have larvae that can drift over large distances, and most are thought to have large geographic ranges. The greater the geographic diversity, the less the likelihood for extinction.

According to the Pew Center on Global Climate Change, many scientists now agree that the seeming lack of evidence for recent marine extinctions is a result of limited information on biodiversity. That group points out too that not all marine species have drifting larvae, and that many larvae are short-lived or remain relatively close to the parental population before becoming juveniles.

The first scientific report of a marine invertebrate extinction didn't appear until 1991. One problem with this research has been that, because marine species tend to range far and wide, their disappearance is hard to prove. In a geographically restricted terrestrial environment, like a rain forest, it is easier to estimate the number of a particular species and validate a species' disappearance. By contrast, the first visible sign of danger in a marine environment is often a widespread change in the abundance of a species.

The Ocean Conservancy says as many as one-third of known fish species currently are threatened. In addition to biological extinction, experts point also to "commercial extinction," when a species is so depleted that it no longer may be a candidate for harvesting.

Another concern arises with the disappearance of fish from specific areas or ecosystems. For example, a number of salmon, including valuable native species such as Chinook, sockeye, and Atlantic, are listed as endangered or threatened throughout much of their range.

The American Fisheries Society, in a study in 2000, listed 82 fish species, subspecies, and populations as "vulnerable, threatened, or endangered" in North American waters. Among those listed are sharks, sawfish, skates, sturgeons, cod, rockfishes, snooks, groupers, gobies, pipefishes, seahorses, Pacific smelts, and Atlantic halibut.

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The National Research Council listed the most critical contributors to changes in marine biodiversity:

• overfishing and removal of the ocean's invertebrate and plant stocks, many of which have been overexploited -- to the extent that some of the world's greatest fisheries (such as the Grand Banks and Georges Banks) have now been closed;
• chemical pollution and eutrophication -- by a "cocktail" of pollutants that, in addition to changing biodiversity, has increased incidence of tumors and diseases in marine species;
• alterations to coastal habitat, as vast amounts of shoreline have been dredged, diked and filled and human activities such as agriculture and deforestation have altered patterns of sedimentation, erosion and freshwater flow;
• invasions of exotic species (on a typical day more than 3,000 species of marine animals and plans are in silent motion around the world, traveling in ships' ballast water, eventually to be discharged at distant locations far from their point of origin, and marine ballast represents just one part of the invasive species equation); and
• global climate change, including increased ultraviolet radiation and potentially rising sea surface temperatures, resulting in possible changes to ocean circulation (and thus nutrient supply and distribution).

The NRC report elaborated on potential impacts of continued loss of marine biodiversity:

• dramatic reductions in most of the preferred edible fish and shellfish species in the world's oceans;
• reduction or loss of species with important potential for biomedical products;
• altered aesthetic and recreational value of many coastal habitats, such as coral reefs, bays, marshes, rocky shores, and beaches;
• vast changes in the species composition and abundance of the ecologically important animals and plants within and between impacted ecosystems; and
• changes in the basic functioning of ecosystems, including the rates and sources of primary production, the stability of populations, the amount of energy flow, and biogeochemical cycling.

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Sources & Contacts

All Species Foundation. A non-profit organization dedicated to the complete inventory of all species of life on Earth within the next 25 years -- one human generation. http://www.all-species.org.

Census of Marine Life. A decade-long international research program assessing and explaining the diversity, distribution and abundance of marine organisms throughout the oceans. http://www.coml.org.

Center for Marine Biodiversity. Part of the Bedford Institute of Oceanography in Dartmouth, Nova Scotia. http://www.marinebiodiversity.ca/home.html.

Convention on Biological Diversity. This is the site for the international agreement. http://www.biodiv.org/.

Greek Fisheries Research Institute, part of the National Agricultural Research Foundation, located in Crete, Greece. Prof. Anastasios Eleftheriou at fri@otenet.gr or http://www.fishri.gr (site in Greek or English).

http://www.coreocean.org/Dev2Go.web?id=205640&rnd=15669. This is the site for the History of Marine Animal Populations, coordinated by the Southern Denmark University, the University of Hull (UK), and the University of New Hampshire (USA).

Institute of Marine and Coastal Sciences, Rutgers University, N.J. J. Frederick Grassle at grassle@imcs.rutgers.edu or website at http://marine.rutgers.edu.

Marine Conservation Biology Institute, Redmond, Wa. A seven-year-old nonprofit, tax-exempt scientific and conservation advocacy organization Elliott Norse at Elliott@mcbi.org or website at http://www.mcbi.org.

National Resource Center for Cephalopods, University of Texas Medical Branch, Galveston, TX 77555-1163. All you want to know about cephalopods (marine mollusks of the class Cephalopoda, such as the octopus, squid, cuttlefish, or nautilus) James B. Wood at ceph@is.dal.ca or website at http://www.nhm.ac.uk/hosted_sites/tcp/index.html.

National Oceanic and Atmospheric Administration, U.S. Department of Commerce. The leading U.S. federal government department dealing with oceans and atmospheric issues. http://www.nmfs.noaa.gov/prot_res/overview/biodiversity.html and http://www.nccos.noaa.gov/publications/notables.html#corals.

The National Research Council's Ocean Studies Board and Board on Biology, which founded the Committee on Biological Diversity in Marine Systems in 1993. The Committee's report, "Understanding Marine Biodiversity," published by the National Academy Press in 1995, urged a national research program and research agenda. http://www.nap.edu/catalog/4923.html.

http://www.shiftingbaselines.org/ A partnership involving The Ocean Conservancy, a membership advocacy organization, marine biologists, ocean conservationists, underwater cinematographers, and Hollywood filmmakers "to provide a single, clear description of the state of ocean decline that is not limited by concerns about market share or membership." For Ocean Conservancy, "the largest and oldest organization dedicated solely to protecting the oceans," http://www.oceanconservancy.org/dynamic/home/home.htm.

United Nations Environment Programme. World Conservation Monitoring Centre (UNEP-WCMC) publication: World Atlas of Biodiversity: Earth's Living Resources in the 21st Century. This first comprehensive map-based view of global biodiversity includes information on wetlands, marine and coastal environments. http://www.unep-wcmc.org/information_services/publications/biodiversityatlas/presspack/press/briefing.htm.

World Conservation Union. Founded in 1948, this international group of states, government agencies, and select nonprofits has nearly 1,000 members in some 140 countries. http://www.iucn.org.

World Resources Institute. A respected, influential and generally progressive Washington, D.C.-based environmental "think tank." http://www.wri.org/wri/biodiv/b04-gbs.html.

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This press backgrounder is one of a series on marine biodiversity published as a supplement to Environment Writer newsletter, published by the Metcalf Institute for Marine & Environmental Reporting, located at the University of Rhode Island's Graduate School of Oceanography, in Narragansett, R.I., and as part of the overall Census on Marine Life program. Future installments in this series will be published over the next several months. Funding for this series was provided to CoML by the Alfred P. Sloan Foundation.

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