NEWS TIPS FROM THE February 2003 ISSUE OF CONSERVATION BIOLOGY the journal of the Society for Conservation Biology

FOR IMMEDIATE RELEASE

Please mention Conservation Biology as the source of these items:

• FOREST FRAGMENTATION MAY INCREASE LYME DISEASE RISK
• MARINE RESERVES CAN'T DO IT ALL: SEA OTTERS VS. RED ABALONE
• HIKERS MAY DISRUPT MEXICAN SPOTTED OWL BREEDING
• MIDWEST WETLANDS ALMOST GONE BUT MAY STILL HAVE MOST SPECIES
• SPECIAL SECTION: INVASIVE SPECIES

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FOREST FRAGMENTATION MAY INCREASE LYME DISEASE RISK

Having a patch of woods in your backyard may boost your spirits but could threaten your health. New research shows that small forest fragments in New York have more Lyme disease-carrying ticks, which could increase peoples' risk of the disease.

"These results suggest that...habitat fragmentation can influence human health," say Felicia Keesing of Bard College in Annandale, New York; Brian Allan of Rutgers University in New Jersey; and Richard Ostfeld of the Institute of Ecosystem Studies in Millbrook, New York, in the February issue of Conservation Biology.

While fragments generally have fewer species than continuous habitat, some species actually do better in small patches. Notably, white-foot mice are more abundant in forest fragments in parts of the U.S., presumably because there are fewer predators and competitors left. White-footed mice are particularly abundant in fragments smaller than about five acres, and this could mean trouble for people living nearby because the mice are the main carriers of Lyme bacteria. In eastern and central North America, people catch Lyme disease via blacklegged ticks: first, larval ticks feed on infected mice, and then the infected larvae molt into nymphs that bite people.

Lyme disease is concentrated in areas where lots of people live near forest with blacklegged ticks and their hosts. Lyme disease is rising in the U.S. and is far more common than West Nile virus and other mosquito-borne diseases.

To see if forest fragmentation could increase the risk of Lyme disease, Keesing and her colleagues studied blacklegged tick nymphs in 14 forest patches ranging from 1.7 to about 18 acres in Dutchess County, New York, which recently has had the most people with Lyme disease in the U.S. The researchers determined the densities of both tick nymphs and infected tick nymphs.

The researchers found that smaller forest fragments had both more tick nymphs and more infected tick nymphs, which could mean more Lyme disease. Fragments that were smaller than three acres had an average of three times as many total nymphs than the larger fragments did (0.1 vs. 0.03 nymphs per study plot) and seven times more infected nymphs (0.07 vs. 0.01 infected nymphs per study plot). As many as 80% of the nymphs were infected in the smallest patches, the highest rate the researchers have seen.

"Our results suggest that efforts to reduce the risk of Lyme disease should be directed toward decreasing fragmentation of the deciduous forests of the northeastern United States into small patches, particularly in areas with a high incidence of Lyme disease," say Keesing and her colleagues. "The creation of forest fragments of less than five acres should especially be avoided."

CONTACT:

Felicia Keesing (845-758-7837, keesing@bard.edu)
Richard Ostfeld (845-677-7600 X136, rostfeld@ecostudies.org)

MARINE RESERVES CAN'T DO IT ALL: SEA OTTERS VS. RED ABALONE

California's sea otters and red abalone fisheries both need help -- but what's the best way to protect predators as well as their prey? New research suggests that the answer is separate reserves.

"We conclude that coastal marine protected areas off California cannot enhance abalone fisheries if...they also contain sea otters, " say Samantha Fanshawe, who did this work while at the University of California at Santa Cruz, and is now at the U.K.'s Marine Conservation Society; Glenn VanBlaricom of the University of Washington in Seattle; and Alice Shelly of TerraStat Consulting Group in Seattle, Washington, in the February issue of Conservation Biology.

California's red abalone population is so low that all of the commercial fisheries and all but one of the recreational fisheries are closed. Similarly, California's sea otter population is at roughly 2,000 and is dropping by about 1-2% each year. While the state has two marine reserves that protect the otters from people, there are none that protect the abalone from otters.

To see if reserves can both protect the sea otters and rebuild the red abalone fisheries, Fanshawe and her colleagues studied red abalone at six sites, four with and two without sea otters. The sites with otters were off Monterey County and the sites without otters were off Sonoma County; abalone harvesting is prohibited at all six of the sites. The researchers determined the abundance and size of red abalone at two depth zones: "shallow" (about 10-15 feet) and "deep" (about 25-33 feet). Sea otters can dive as deep as 330 feet and so can easily reach abalone on both zones.

Fanshawe and her colleagues found that red abalone were far more abundant at the sites without sea otters: there were about seven times more of the abalone in the "deep" zones (15.6 vs. 2.2 per study plot), and nearly 20 times more in the "shallow" zones (17.5 vs. 0.9 per study plot). In addition, the abalone were an average of nearly two times bigger at the sites without sea otters (7.2 vs. 3.7 inches; the legal limit for harvest is 7 inches).

This work shows that "calls for management of marine protected areas for multiple human uses may be ecologically naive, creating unattainable expectations for performance," say Fanshawe and her colleagues. The researchers call instead for single-use marine reserves that focus either on ecosystem restoration or on fishery development. This approach has been adopted in the Florida Keys National Marine Sanctuary, where managers have split a former multiple-use protected area into smaller areas with goals that are less likely to conflict.

CONTACT:

Samantha Fanshawe (44-01989 566017, sam@mcsuk.org)
Glenn VanBlaricom (206-543-6475, glennvb@u.washington.edu)
Alice Shelly (206-362-3299, alice@blarg.net)

HIKERS MAY DISRUPT MEXICAN SPOTTED OWL BREEDING

Imagine if people kept hiking through your baby's room. That's essentially what happens in some of the canyons where Mexican spotted owls breed, and a new study shows that hikers can disrupt the owls' behavior in ways that might harm their young.

"We suggest that restrictions on hiking intensity should be considered for canyons with high levels of human activity," say Elliott Swarthout, who did this work while at the University of Arizona in Tucson and is now at the Cornell Laboratory of Ornithology in Ithaca, New York, and Robert Steidl of the University of Arizona in Tucson in the February issue of Conservation Biology.

The threatened Mexican spotted owl lives in coniferous forests in the Southwest and Mexico. In Utah, the birds nest, roost and hunt almost entirely in steep, narrow canyons. Hiking and other recreational activities along the canyon bottoms are highest from March-October, which overlaps with the owls' breeding season.

To see if hiking affects the owls, Swarthout and Steidl studied 10 nests during the breeding season in Utah's Canyonlands and Capitol Reef national parks, which had more than 400,000 and 650,000 visitors per year, respectively, during the two-year study period. The nests were 36-223 feet above the canyon bottoms, and the researchers observed the owls during a series of experimental "hiking treatments": a hiker passed under a given nest every 15 minutes for four hours during three time periods (early morning, mid-day and evening).

Swarthout and Steidl found that hiking primarily affected the female owls: notably, females spent nearly 60% less time on prey-handling activities such as feeding their young, and a third less time on daytime maintenance activities such as tending the nest, and preening themselves and their young. Preening is important to birds' health in part because it reduces parasites.

Because female Mexican Spotted Owls provide virtually all of the parental care, these behavioral changes could harm their young. Fewer than a third of the young survive anyway, and getting less food and other kinds of care could make them even more vulnerable.

The experimental hiking level in this study is higher than the actual hiking levels in most of southern Utah's canyons. However, several of the canyons where the owls live have more than 50 visitors per day, which is close to the experimental hiking level. In such areas, the researchers recommend protecting owl habitat during the late March–early June nesting season by limiting hiking or establishing buffers around nest sites. The researchers had previously found that 95% of owls were not flushed when hikers stayed about 80 feet away; however, many canyons are so narrow that buffers of this size would preclude hiking in them.

Swarthout and Steidl's work is being used to help establish recreational guidelines around Mexican spotted owl territories on federal lands in Arizona, New Mexico and Utah.

CONTACT:

Elliott Swarthout (607-254-2123, mes243@cornell.edu)
Robert Steidl (520-626-3164, steidl@ag.arizona.edu)

This former wetland is now an agricultural field, complete with drain pipes to eliminate water in a matter of days

MIDWEST WETLANDS ALMOST GONE BUT MAY STILL HAVE MOST SPECIES

Wetlands in the Midwest? It may be hard to believe but vast areas of today's Corn Belt used to get so wet that malaria was common. While the remaining wetlands are small and scattered, there's still hope -- new research shows that most of the original species may still survive.

"We often look to other regions of the world as biodiversity hotspots but it is worth noting that some of the most heavily impacted regions – such as the Corn Belt – should not be written off as biodiversity wastelands," says David Jenkins of the University of Illinois at Springfield, who presents this work with Scott Grissom of Grand Valley State University in Allendale, Michigan, and Keith Miller of the University of Illinois at Springfield in the February issue of Conservation Biology.

This agricultural field is also the site of a small wetland area

In the mid-1800s, much of the Corn Belt – Iowa, Illinois, Indiana and Ohio -- was tallgrass prairie that included extensive seasonal wetlands. For instance, ephemeral ponds used to cover about a fifth of Illinois (nearly five million acres) from roughly early spring to mid-summer. By the mid-1900s, about 85% of these wetlands had been drained and converted to agriculture, which is similar to the rate of deforestation in tropical forests today.

To assess the biodiversity of the Midwest's remaining wetlands, Jenkins and his colleagues studied crustaceans in 13 ephemeral ponds near Bluff Springs, Illinois; the ponds were wide and shallow, three feet deep at most. They chose crustaceans because they are usually diverse and are important to these ecosystems. The researchers sampled crustaceans from the ponds every week during the wet seasons of three years. Because there are no good records of the species that lived in Illinois' wetlands historically, the researchers used their findings to extrapolate backwards and estimate how many crustacean species were there originally and how many have gone locally extinct. These estimations were based on the fact that the number of species depends on how widely distributed they are.

Jenkins and his colleagues found 33 crustacean species in the ponds they studied. These included fairy shrimp, which are large (up to 1.5 inches), delicate and glide around on their backs; clam shrimp, which are dark brown, the size of a pencil eraser, and extremely active; and copepods, which are bright red and swarm in clouds below the surface of the water.

Extrapolating backwards, the researchers estimate that there were as many as 85 crustacean species in Illinois' seasonal wetlands before they were drained. Similarly, the researchers estimate that 8-9 of the original crustacean species may have gone locally extinct.

Taken together, these findings suggest that 90% of the original crustacean diversity may still survive in the few remaining seasonal wetlands in Illinois. This means that despite the huge habitat losses, there could still be time to conserve most of the original species. "Their existence will depend on our attention and action," says Jenkins.

CONTACT:

David Jenkins (217-206-7341, Jenkins.David@uis.edu)
Scott Grissom (616-331-2088, grissom@gvsu.edu)
Keith Miller (217-206-7327, miller.keith@uis.edu)

SPECIAL SECTION: INVASIVE SPECIES

Invasive non-native species are among the greatest threats to biodiversity worldwide. There are about 50,000 non-native species in the U.S. alone, costing about $125 billion each year in environmental damage and economic losses. While there are no easy answers, a new analysis shows that current approaches often just make the problem worse.

"Management and control of [non-native] species is perhaps the biggest challenge that conservation biologists will face in the next few decades," says Fred Allendorf of the University of Montana in Missoula, who edited a six-paper special section called "Population Biology of Invasive Species" in the February issue of Conservation Biology.

Key points in the special section include:

• Arguments that species invasions are natural and so acceptable are false. While it is true that invasions have occurred throughout evolutionary history, people have greatly accelerated the rate of introductions so that there are far more invasions today than there were only a few hundred years ago. Similarly, arguments that new species will evolve to replace those lost to invasions are also flawed. Even if this is true – and that's a big if -- it would take millions of years. This work is by David Lodge and Kristin Shrader-Frechette of the University of Notre Dame in Indiana.

• It's hard to get rid of invasive species that benefit some people economically. For instance, the non-native brown trout has had huge effects on the freshwater ecosystems of New Zealand's South Island. The widespread brown trout eat five times as many mayfly larvae and other stream invertebrates, increasing the algae level six times and decreasing the nutrient levels in the water. Moreover, streams with brown trout often do not have native fish. But there is little support for eradicating the brown trout because the sport fishery is so popular, generating more than $300 million per year. On the positive side, the story of the brown trout helped the New Zealand government decide that the risks of importing the channel catfish for aquaculture were too great. This work is by Colin Townsend of the University of Otago in New Zealand.

• Invasions often owe their success to fundamental biological differences between introduced populations and the original populations in their native range. A prime example is Argentine ants, which are now found on six continents. In their native range Argentine ant colonies attack outsiders, which are distinguished via chemical cues based on genetic differences. But the introduced colonies generally don't attack each other because they can't distinguish each other -- they are quite similar genetically because they descended from a small number of introduced ants. The result is that the introduced colonies cooperate with each other, forming "supercolonies" that outnumber and wipe out native ants. "A single supercolony occupies virtually all [of the Argentine ant's] California range," say Neil Tsutsui of the University of California at Davis and Andrew Suarez of the University of California at Berkeley.

• While only a small percentage of introduced species actually become invasive, it's hard to predict which ones will. One of the reasons is that some species rapidly adjust to or evolve in new environments. "With the introduction of non-native species, evolution is our largest source of uncertainty and therefore our largest source of anxiety," say Ingrid Parker, Joseph Rodriguez and Michael Loik of the University of California at Santa Cruz. "We lose the ability to predict where an introduced species will end up and what sort of impact it will have."

• Biocontrol should be a last resort because it can do more harm than good. The problem is that the natural enemies introduced to control invasive non-native species can also harm native species. And more often than not, biocontrol doesn't even work. One reason is that the tests to predict the effectiveness and specificity of proposed biocontrol agents are often inadequate, which can lead to surprises when they are released in the field. For instance, a European seed-eating weevil was predicted to prefer the invasive Canada thistle but ended up preferring the native Tracy's thistle in Colorado. There are few, if any, options for addressing biocontrol gone amok. "'Recall' of problematic species from ecosystems where they are damaging native species is either impossible or prohibitively expensive," say Svata Louda and three colleagues at the University of Nebraska in Lincoln.

• From a conservation standpoint, the best approach to invasive species is a combination of a no-tolerance policy for non-native species and immediate eradication of any that are found. "Shoot first, ask questions later," says Daniel Simberloff of the University of Tennessee at Knoxville. All too often, studies to determine the best way of controlling an invasive species take such a long time that the species spreads significantly, making it much harder and more expensive to control. Simberloff argues for using whatever methods are currently available, adopting any new methods as they are found. This "brute force" approach has controlled plenty of invasions effectively: for instance, rats, goats, and other introduced mammals were eradicated from Mexican islands with traps, hunting dogs and rifles; and witchweed, an African root parasite, is controlled in the Carolinas with herbicides and a rigorous quarantine on anything that could carry soil out of infested areas.

CONTACT:

Fred Allendorf (406-243-5503, fred.allendorf@mso.umt.edu)
David Lodge (lodge.1@nd.edu)
Colin Townsend (colin.townsend@stonebow.otago.ac.nz)
Neil Tsutsui (ndtsutsui@ucdavis.edu)
Ingrid Parker (parker@biology.ucsc.edu)
Svata Louda (slouda@unl.edu)
Daniel Simberloff (dsimberloff@utk.edu)