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NEWS TIPS FROM THE June 2003 ISSUE OF CONSERVATION BIOLOGY the journal of the Society for Conservation Biology
FOR IMMEDIATE RELEASEPlease mention Conservation Biology as the source of these items:
PDFs of these papers are available to the media; contact Robin Meadows robin@nasw.org Images are provided by the researchers; please contact them directly for more information. To register for media access to the TOC and our expert directory: http://www.conbio.org/scb/information/media/ For more information about the Society for Conservation Biology: http://conservationbiology.org
EATING BATS LINKED TO NEUROLOGICAL DISEASE
Maybe you really are what you eat. This would solve the long-time mystery of why so many of Guam's Chamorro people - up to a third per village -- suffered a devastating neurological disease. A new study suggests that they gorged on flying fox bats that in turn had feasted on neurotoxin-laden cycad seeds. "Through the consumption of cycad-fed flying foxes, the Chamorro people may have unwittingly ingested large quantities of cycad neurotoxins," say Clark Monson of the University of Hawaii, Honolulu, Sandra Banack of California State University, Fullerton, and Paul Cox of the National Tropical Botanical Garden in Kalaheo, Hawaii, in the June issue of Conservation Biology. Guam's indigenous Chamorro people historically had a high incidence of a neurological disease with similarities to Lou Gehrig's, Parkinson's and Alzheimer's diseases. Called ALS-PDC (amyotrophic lateral sclerosis-Parkinsonian dementia complex), the disease's symptoms range from muscle weakness and paralysis to dementia. The rate of ALS-PDC has been as much as 100 times higher in Guam's Chamorro people than in the continental U.S. Monson and his colleagues hypothesized that the answer might be another thing unique to Guam's Chamorro people: they love to eat the local flying foxes. These bats, which have a three-foot wing span, are served at Chamorro weddings, village fiestas and religious events. The preparation is simple: wash and boil whole, and then eat the entire bat -- wings, brains, fur and all.
Eating too many of these flying foxes could be dangerous because they like to eat cycad seeds, which contain a neurotoxin called BMAA (beta-methylamino L-alanine). The bats are probably neurotoxin-rich because studies have shown that when rats ingest BMAA, most (90%) of it stays in their bodies rather than being excreted. Several lines of evidence support the link between eating these bats and contracting the neurological disease. Previous studies have shown that Chamorro populations outside of Guam do not have higher incidences of the disease, suggesting that it is caused by an environmental factor. In addition, the disease is three times more common in men than in women, and men like to eat the entire bat while women tend to eat only the breast meat. Finally, the incidence of the disease rose after people began hunting flying foxes for commercial trade and then dropped as the bat population fell. Eating wildlife has threatened people's health in other cases. Thousands of people in Kyushu, Japan, who ate mercury-contaminated fish suffered neurological problems, birth defects or even death. And people living in the Faroe Islands eat whale meat and have high levels of mercury and PCBs. Eating wild animals that have not been commercially traded for a long time may be particularly risky because they could have unknown health risks. "We urge caution in the consumption of recently commercialized wildlife species," say Monson and his colleagues. CONTACT: Clark Monson (csm7@email.byu.edu)
MONOGAMOUS ANIMALS MAY BE MORE LIKELY TO DIE OUTNew research reveals a surprising risk factor for extinction: monogamy. Large mammals that live in pairs or have small harems are far more likely to die out than those with big harems in reserves in Ghana. "In avoiding extinction, it pays to be promiscuous," says Justin Brashares of the University of British Columbia in Vancouver, who presents this work in the June issue of Conservation Biology. "This study is the first to show a strong link between social behavior and risk of extinction in mammals." Most studies of risk factors for extinction are based on natural extinctions through the ages - but other risk factors may be at play in today's world, where the extinction rate is unnaturally high due to overhunting, habitat fragmentation and other disturbances caused by people. Knowing which species are particularly sensitive to these disturbances would help conservationists figure out how to save them. Since 1970, more than half of the mammal populations in Ghanian reserves have become locally extinct. "This shocking loss of abundance and local diversity is occurring throughout Africa," says Brashares. To help identify the risk factors for modern extinctions, he analyzed the extinctions and persistences of large mammals in six reserves in the savannas of Ghana, where the mammals have been censused monthly for more than 30 years and 78 local extinctions have been documented. Brashares assessed the extinction risk of nine traits (including population isolation, harem size, abundance and how much people like to eat them) in 41 mammal species (9 primates, 24 ungulates and 8 carnivores). After accounting for the effect of reserve size, Brashares found that two of the factors studied correlated with local extinctions in the Ghanian reserves. The first is population isolation, which is not surprising because this was previously known to be a risk factor for natural extinctions. The second is harem size: mammals that are monogamous or have small harems were more prone to extinction. For instance, several duiker species, which are monogamous, died out an average of 10 years after the reserves were established, while the African buffalo, which has harems with about 15 females, is still living in all the reserves. Similarly, several colobus monkey species, which have few mates, died out an average of 18 years after the reserves were established, while green monkeys and baboons, which have many mates, are still living in all the reserves. How could being monogamous make animals more vulnerable to extinction? No one knows for sure but there is some evidence that hunters take more males than females from populations, which could lead to a dearth of males available for pairing in monogamous species. In contrast, species with large harems are more likely to have plenty of "spare" males. Another possibility is that when animals live in pairs or small groups, they are less likely to detect approaching hunters. "It may just be that it's a lot easier to sneak up on one or two animals than it is 20," says Brashares. This work suggests that managers should target conservation efforts and monitoring on species that are monogamous or live in small groups. "This could mean using them as indicator or umbrella species, or just giving these species special attention," says Brashares. CONTACT: Justin Brashares (604-822-0862, justinb@zoology.ubc.ca)
EVEN "NON-DESTRUCTIVE" FISHING CAN THREATEN CORAL REEF FISH
Catching coral reef fish for the aquarium trade used to mean using cyanide or even dynamite, which destroyed much of the reef ecosystem. Today the trend is to use non-destructive methods such as hand-net fishing, and fish importers argue that this means coral reef fish can be harvested continuously - but new research suggests otherwise. "The phrase 'non-destructive fishing methods' often used by those in the aquarium trade may actually be highly misleading with respect to the conservation status of reef fish," say Niclas Kolm and Anders Berglund of Uppsala University in Sweden in the June issue of Conservation Biology. Coral reefs have the greatest diversity of fish worldwide and many species are unique to particular reefs. Prized for their bright colors, coral reef fish are harvested by the hundreds of thousands each year. While non-destructive fishing methods are clearly an improvement over cyanide and dynamite, they are not necessarily benign and little is known about their effects on fish populations. Kolm and Berglund studied the effects of a non-destructive fishing method on the Banggai cardinalfish, which is about two inches long and is silver with black stripes. Popular in North America, Japan and Europe, the fish has been found only in the Banggai archipelago off the east coast of Sulawesi, Indonesia, and is fished throughout its range. Banggai cardinalfish live in groups near long-spined sea urchins and seek shelter in the urchins when threatened. Fishermen take advantage of this behavior by pushing urchins into a cage with a stick, which tricks the fish into swimming right in after them. The researchers monitored the Banggai cardinalfish at eight sites in the archipelago and interviewed local fishermen to assess the fishing intensity, which ranged from low (never or rarely fished) to high (frequently fished).
Kolm and Berglund found that fishing cut the size of Banggai cardinalfish groups by half. Specifically, while the average number of fish per group was 11.5 at low-intensity fishing sites, it was only 5.7 at high-intensity fishing sites. This is troubling because at the time of the study, the species had been commercially fished for only six years and the industry is still expanding. "Our data suggest that the popular Banggai cardinalfish is under threat from the aquarium trade industry," say the researchers. The fishery could threaten the Banggai cardinalfish in two ways. First, fishermen move to new sites after depleting the old ones, and depleted populations are unlikely to be replenished because young Banggai cardinalfish apparently do not disperse far. Second, pushing the sea urchins with a stick often damages them, and the researchers found that the size of a given Banggai cardinalfish population depends on the size of the associated urchin population. There is, however, an easy way to turn this into a win-win situation for both the fish and the fishermen. Banggai cardinalfish can be raised reliably and cheaply in aquariums, and the researchers are currently encouraging local people to do so. "A fruitful industry could be developed with little or no negative impact on the Banggai cardinalfish," say Kolm and Berglund. CONTACT: Niclas Kolm (+46-18-471-6495, niclas.kolm@ebc.uu.se)
HOW MANY SPECIES ARE THERE, ANYWAY?
One barrier to protecting biodiversity is that there are no good ways of figuring out how many species there are in large areas. Now we may finally be able to find out: a new method accurately predicts the total number of North American butterfly species even when only a tenth of the ecoregions are sampled. This could "at last enable ecology to estimate worldwide species diversity," say Michael Rosenzweig, Will Turner and Jonathan Cox of the University of Arizona, Tucson, and Taylor Ricketts of Stanford University in Stanford, California, in the June issue of Conservation Biology. While conservationists can predict how many species there are within a single habitat, the usefulness of this approach is limited because it's impossible to sample all the habitats in large areas. Knowing the number of species is critical to tracking - and addressing -- declines in biodiversity. "Right now we can only guess that the correct answer for the total number of species worldwide lies between 2 and 100 million," says Rosenzweig.
To help find a way to assess biodiversity in large regions, Rosenzweig and his colleagues tested six methods for assessing biodiversity in a single habitat on a remarkably well-known group of species: butterflies in the U.S. and Canada. Because butterflies are so popular, we have an unusually complete set of data for which species live where. There are 561 known butterfly species and 110 ecoregions in the U.S. and Canada, and the researchers determined which of the six methods predicted the total number of species most accurately based on data from the smallest number of ecoregions.
The researchers have even more encouraging news. Rosenzweig and his colleagues have recently found that their approach also works for assessing the large-scale biodiversity of many other groups of species, from marine invertebrates to birds. "It points the way for getting the answer to how many species there are worldwide," says Rosenzweig. CONTACT: Michael Rosenzweig (520-621-7296, scarab@u.arizona.edu)
WEBSITE: Tucson Bird Count
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