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NEWS TIPS FROM THE February 2004 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; please register for the Society for Conservation Biology's media services at: http://conbio.org/SCB/Information/Media/ Images are provided by the researchers; please contact them directly for more information. For more information about the Society for Conservation Biology: http://conservationbiology.org
HAVING OUR WINE AND OUR WILDLIFE TOORiparian corridors could help animals survive Northern California's vineyard expansion
California wines are so popular that vineyards are rapidly replacing and fragmenting oak woodlands in the northern part of the state. Preserving plant strips along streams could help wildlife but the size of these corridors is hotly contested. New research suggests that wider is better: wider corridors had twice as many native predator species as narrower ones. "Wide corridors may be necessary to retain the full complement of native species," say Jodi Hilty, who did this work while at the University of California, Berkeley, and is now with the Wildlife Conservation Society in Bozeman, Montana; and Adina Merenlender of the University of California, Berkeley, in the February issue of Conservation Biology. Northern California's vineyards have many small streams that could provide good wildlife corridors. The size of riparian setbacks is currently being debated in Sonoma County, one of the best places to grow wine grapes in California. To see how setback size might affect predators' use of riparian corridors in
wine grape growing regions, Hilty and Merenlender set remotely-triggered cameras
in 21 corridors in six Sonoma County vineyards. Five of the corridors were wide
(more than 90 feet on each side of the creek), 7 were narrow (between 30-90
feet) and 9 were denuded (less than 30 feet). The native predators detected
included bobcats, coyotes, gray foxes, raccoons and striped skunks. The findings suggest that the wide corridors are better for native predators. Wide corridors had twice as many native predator species as narrow or denuded corridors - bobcats, gray foxes and striped skunks were detected more often in wide corridors, while raccoons were detected at about the same rate in all three types of corridors. In addition, native predators used wide corridors nearly twice as much as narrow ones and more than three times as much as denuded ones. The narrow corridors in this study are roughly the size of a recommended riparian setback being considered by the Sonoma County Board of Supervisors. Hilty and Merenlender's work suggests that this setback would not be enough to help many of the predators studied.
In addition, the researchers did not detect badgers, long-tailed weasels and several other predators native to Sonoma County. This suggests that even the wide corridors in this study may not be enough. "It is unlikely that corridors will fully mitigate the effects of fragmentation for all species," say Hilty and Merenlender. CONTACT: Jodi Hilty: 406-522-9333, jhilty@wcs.org
WEBSITES: University of California Integrated Hardwood Range Management Program
Vineyard Landscape: Wildlife activity along creek corridors
Oak Woodland Wildlife: Critters along the creekside
GOLD MINING SEDIMENT THREATENS FISH - AND PEOPLEFine particles clog spawning grounds, reduce food fish in SurinameMercury poisoning has not been enough to make Suriname regulate small-scale gold mining - but sediment may. While hardly as frightening as mercury, sediment can be just as deadly to stream ecosystems. And new research links sediment to a big reduction in food fish in Suriname, which could catch policymakers' attention because fish are the main protein source for people living in Suriname's forests. "The adverse effect of mining-related sediment on the abundance of highly valued food fishes may sooner convince policymakers in Suriname of the need to regulate the informal gold-mining sector...than the slow, secretive danger of mercury," say Jan Mol and Paul Ouboter, both of the University of Suriname in Paramaribo, in the February issue of Conservation Biology. Widespread in tropical South America since the 1980s, small-scale gold mining is one of the few livelihoods in the interior of Suriname. The country has about 15,000 small-scale gold miners who extract soil with high pressure hoses and recover the gold by amalgamation with mercury. However, these miners typically fail to build tailing ponds that would allow the sediment to settle before draining the extraction water into streams. This can harm the many South American fish that are adapted to clear water. Mol and Ouboter compared sedimentation and fish diversity over seven years in two small rainforest streams in the Suriname's Gros Rosebel area, which is near Paramibo. One (Maykabuka Creek) is undisturbed and the other (Mamanari Creek) is in catchment that has had small-scale gold miners since 1994. Both creeks were initially clear but the "mined" creek has been turbid since the first fish survey in 1994. The researchers found that the "mined" creek had nearly 24 times more sediment than the undisturbed creek (estimated at 3.1 vs. 0.13 tonnes/catchment hectare per year). This sediment reduced visibility by about four-fifths and covered the gravel beds, holes in stream banks and other nooks where many fish lay their eggs. By the end of the study, shallow runs had about 5 inches of sediment and deep pools had more than a foot. In contrast, the undisturbed creek's streambed had no measurable fine sediment. The "mined" creek also had a "highly aberrant" fish community, say the researchers. The "mined" creek was dominated by species such as knifefishes that are primarily nocturnal and so well-adapted to low light, while the undisturbed creek was dominated by species such as cichlids that rely on vision for finding prey and caring for their young. In addition, compared to the undisturbed creek, the "mined" creek had:
While mercury is a problem, it is clearly not the only threat from mining. "In their concern over environmental degradation resulting from small-scale gold mining, scientists and the media often have focused on mercury pollution but new technologies for reducing mercury pollution will not reduce the influx of sediment into streams," say Mol and Ouboter. Their recommendations include monitoring sediment levels, building tailing ponds and restoring riparian buffer zones. CONTACT: Jan Mol: 597-490128, fisheco@celos.sr.org
WEBSITE: Cambior http://www.cambior.com/
PERILOUS MIGRATION ROUTE REVEALED FOR CRANESWhite-naped cranes rest in Korean Demilitarized Zone, other unprotected areas
Protecting cranes is tricky because they migrate up to thousands of miles through countries that don't always get along. White-naped cranes migrate between Russia and China or Japan, and a new satellite-tracking study shows that most of their rest sites along the way are poorly protected. It's difficult to coordinate countries "whose politics are in flux and among whom relationships can be tense," say Hiroyoshi Higuchi of the University of Tokyo and nine co-authors in the February issue of Conservation Biology. Cranes are among the most endangered birds worldwide, with 10 of the 15 species threatened by extinction. White-naped cranes (which are gray-and-white with red eye patches) are down to about 5,000. Most cranes migrate, covering distances of 250-2,500 miles and often going across international borders and through politically sensitive areas. White-naped cranes migrate about 1,600 miles from their breeding grounds in eastern Russia to their wintering grounds in China and Japan. To see where the birds rest as they migrate, Higuchi and his colleagues satellite-tracked 11 white-naped cranes from three nature reserves in eastern Russia (Daursky Nature Reserve, Khingansky Nature Reserve and Muraviovka Wildlife Refuge) to Poyang Lake, China, and Izumi, Japan. The researchers found that the cranes migrated for about 156 days and rested at 4-12 sites en route. Eight of these are "common rest sites" that were used by a number of cranes, and two of them are in the Korean Demilitarized Zone (DMZ). The researchers also found that the cranes' rest sites are poorly protected - more than two-thirds of them are not in nature reserves. For example, while the cranes have been designated "natural monuments" in the Korean DMZ, their habitat is not protected there. Right now civilians are prohibited from the Civilian Control Zone along the DMZ but this could change as politics in the region change. "Any future development along the DMZ would pose a serious threat to important crane habitats," say Higuchi and his colleagues. Another problem is that the cranes may not really be protected even in officially designated reserves. In China, for example, nature reserves used by cranes are also used by people for activities including fishing, grazing and mining. Moreover, some reserves are so small that many cranes are outside the formally protected areas. For example, a third of the white-naped cranes resting within six miles of the Yellow River Delta/Bohai Bay Nature Reserve were outside the reserve boundaries. To help protect the white-naped crane, Higuchi and his colleagues recommend establishing or extending reserves at common rest sites. These reserves would also protect the many other species that rest in these areas, such as red-crowned and Siberian cranes, and the threatened great bustard. On a broader scale, the researchers join other conservationists in envisioning international networks of reserves along crane migration flyways. And despite the political tensions among various countries, Higuchi and his colleagues say there is hope for international cooperation, citing the wildlife refuge on the border between Russia and China at Lake Khanka-Xinghai. CO-AUTHORS: Johanna Pierre, who did this work at the University of Tokyo and is now at the New Zealand Department of Conservation in Wellington; Vladimir Krever of the Worldwide Fund for Nature Russia in Moscow; Vladimir Andronov of the Khingansky Nature Reserve in Oblast, Russia; Go Fujita of the University of Tokyo; Kiyoaki Ozaki of the Bird Migration Research Center in Chiba, Japan; Oleg Goroshko of the Daursky Nature Reserve in Chita, Russia; Mutsuyuki Ueta of the Wild Bird Society of Japan in Tokyo; Sergei Smirensky of Moscow State University; and Nagahisa Mita of NTT Wireless Systems Laboratories in Kanagawa, Japan.
CONTACT: Hiroyoshi Higuchi: +81-(0)3-5841-7541, higuchi@es.a.u-tokyo.ac.jp
BIOLOGICAL CONTROL OF INVASIVE SPECIESDoes it work or just make things worse?People have been introducing natural enemies to control invasive species for hundreds of years. But the practice has gotten a lot of unfavorable press lately. Has biocontrol been bashed unfairly or does it deserve a bad reputation? The latest on the debate is in the February issue of Conservation Biology. Invasive species are among the worst conservation problems worldwide. Non-native species can outcompete native ones, reducing biodiversity and even causing local extinctions. Once established, invasive species are extremely difficult to eradicate. When all else fails "biological control is perhaps the best - and in some cases may be the only - technology for the management and restoration of ecosystems degraded by invasive species," says Mark Hoddle of the University of California, Riverside. For example, the South American red fire ant that has swept through the southeastern U.S. may be controlled by introducing a decapitating fly (the maggots develop in the fire ants' heads, ultimately making them fall off). But biocontrol has something of a bad name because the natural enemies don't always do what people expect. Famously, cane toads were introduced from the Americas to control introduced crop pests in Australia in 1935 - but the toads also gobble up native insects and amphibians, and are toxic to native wildlife. However, "such reckless practices cannot be considered science-based biological control programs," says Hoddle. The keys to successful biocontrol are rigorous criteria and regulations for introducing natural enemies, he says. This means making sure that the natural enemies will target the invasive species rather than straying elsewhere in the ecosystem. New Zealand is a good model because it has among the most stringent data requirements as well as a designated agency that oversees the review process. "Biological control can greatly benefit conservation efforts and - given the devastating impacts of an ever-increasing multitude of invasive organisms - the risks of doing nothing are unacceptably high," says Hoddle. While agreeing that biocontrol can help, other conservationists say we need to be far more careful before introducing even more non-native species to invaded ecosystems. "We still do not know enough to predict the ecological outcomes of new biological interactions," say Svata Louda of the University of Nebraska, Lincoln, and Peter Stiling of the University of South Florida, Tampa. For one thing, biocontrol often fails to work. Only 20% of the weed-control and only 3% of the insect-control programs have been successful, say the researchers. And even when biocontrol fails, the introduced enemies can become established anyway. A third to half of the insects introduced for biocontrol become established without controlling their intended targets. For another thing, recent studies show that current biocontrol programs can still have unexpected - and undesirable - ecological effects. For example, standard laboratory and common garden tests indicated that a Eurasian weevil preferred Canada thistle to thistles native to Colorado. But when the weevils were released in Colorado, it turned out that they actually destroyed more native thistle seeds than Canada thistle seeds. Louda and Stiling fear that there may be many more such cases that we don't know about yet, in part because the non-target effects of biocontrol are rarely monitored. Right now there are two big problems with biocontrol, according to the researchers. First, biocontrol regulations are voluntary or incomplete in most of the world, including the U.S. Second, current tests are not enough for predicting the ecological risks of biocontrol. "The overarching guideline, as in medicine, should be 'first, do no harm'," say Louda and Stiling.
CONTACT: Mark Hoddle: 909-787-4714, mark.hoddle@ucr.edu
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