Thursday, September 17, 2020

Deadly rabbit disease threatens rare cottontail

        It hasn’t yet reached Rhode Island, but local scientists are on the lookout for a disease that rapidly kills wild and domestic rabbits before it wipes out the rarest rabbit in the Northeast, the New England cottontail.
        Rabbit hemorrhagic disease causes what Roger Williams Park Zoo veterinarian Kimberlee Wojick called “very sudden death” in rabbits by attacking internal tissues and causing acute bleeding. The animals seldom show symptoms of the virus and instead are simply found dead with blood coming from their noses.
        The disease can be traced to Europe and Asia, but outbreaks have been reported this year in nine states, resulting in the death of several species of wild cottontails, hares and jackrabbits, mostly in the Southwest.
        “We don’t know how it got to the U.S., but it’s having widespread effects on wildlife,” Wojick said. “The virus can survive for a long time in the environment outside of the rabbit — it’s shed through
New England cottontail (iStock)

their urine and blood, it’s in carcasses and can contaminate food sources — so even though an infected rabbit may have died and been removed from the land, the virus could still be there when a new rabbit moves through.”
        Both species of wild rabbit in Rhode Island, the eastern cottontail and New England cottontail, are highly susceptible to the disease.
        “The eastern cottontail population is large and thriving, so while they may take an overall hit, they won’t be decimated because their population is so high,” Wojick said. “What we are really worried about is the New England cottontail.”
        New England cottontails are the only rabbit native to New England, and they have declined precipitously in recent decades because of habitat loss and competition with eastern cottontails. Efforts are underway to breed the species in captivity at Roger Williams Park Zoo, maintain a breeding colony on Patience Island in Narragansett Bay, and release them into the wild at targeted locations throughout the region.
        “If the disease gets here fast and furious, we could lose the entire remaining New England cottontail population,” said Lou Perrotti, director of conservation at Roger Williams Park Zoo, who is responsible for the captive breeding effort. “It’s that contagious, that ruthless. We could stand to lose a few eastern cottontails, but we don’t have enough New Englands.”
        Conservationists in the region are making plans for how to respond if the disease approaches the area. Much of the planning involves the development of biosecurity protocols so the biologists working with New England cottontails don’t inadvertently move the disease around.
        “There’s a lot of on-the-ground conservation of the species going on, lots of field monitoring of existing populations, biologists trapping rabbits and collecting fecal samples,” Perrotti said. “We’re going to have to do things like disinfect the tires on our trucks, change our clothes, disinfect our traps and bags and anything that holds rabbits. Whenever moving from population to population, we have to be conscious of what we’re bringing and be diligent about proper disinfection methods.”
        The New England cottontail conservation team is in close contact with counterparts in California who are similarly trying to protect the endangered riparian brush rabbit.
        “They’re freaking out about the disease, and their first reaction was to contact us about how to hold a safe, captive population in a bio-secure location,” Perrotti said. “We’re also getting information from them about how they’re dealing with the disease, because that’s a state where it’s already reared its ugly head.”
        The potential saving grace is that a vaccine is available in Europe, though it’s not yet licensed for use in the United States. To get it, conservationists must apply through the U.S. Department of Agriculture (USDA), work through an import broker, and ensure it gets through U.S. Customs while remaining refrigerated. The USDA will not approve applications for the vaccine from states not already affected by the disease, however.
        “We need a positive case in the area before they’d even think about giving us the vaccine,” Perrotti said. “But in an area as small as Rhode Island, if we find a case it’s going to be too late.”
        Assuming the vaccine can be acquired, Perrotti and the cottontail conservation team are developing a plan for how best to administer it. Captive animals will likely be vaccinated first, followed by as many in the Patience Island breeding colony as can possibly be captured.
        “And then we’d opportunistically vaccinate any other rabbit we get our hands on,” he said. “Can we get them all? No. Can we target all populations? No. But we’d prioritize the vital populations that are especially important.”
        According to Wojick, the vaccine only provides immunity to the disease for about one year, and immunity is not transmitted to their offspring. But since the rabbits typically only live for one or two years, a one-year immunity may be sufficient.
        While the arrival of the disease in southern New England isn’t necessarily imminent, it could easily make the leap from the Southwest to Rhode Island by someone transporting an infected domestic rabbit to the area.
        “What we’re most afraid of is some dude that moves East with his domestic rabbits. If they’re infected and he puts them in a hutch outside, wild rabbits will be drawn to the smell of the hay and food and there will be an interaction,” Perrotti said. “That’s all it’s going to take.”
        He noted that Rhode Island doesn’t have large-scale breeding of domestic rabbits for game dinners or laboratory use, as some other states do. And domestic rabbit shows are also not big business in the state.
        “The pet industry is quite large, though, so the risk of getting the disease here is not low,” said Dylan Ferreira, a wildlife biologist at the Rhode Island Department of Environmental Management (DEM). “That being said, COVID has canceled a lot of rabbit shows, and that has helped us mitigate the potential spread.”
        DEM has a fact sheet with detailed recommendations for rabbit breeders and wildlife rehabilitators on biosecurity practices to prevent the spread of the disease. Those who observe unusual rabbit mortalities or other suspicious cases should report them to Ferreira at 401-789-0281 or Scott Marshall, the state veterinarian, at 401-222-2781.

        This article first appeared on EcoRI.org on September 16, 2020.

Wednesday, September 16, 2020

Scientists fight invasive beetle with beetle-killing wasp

        When the invasive emerald ash borer, a beetle native to the Far East, was found in Rhode Island in 2018, it was a sign that most of the state’s mature ash trees were likely to die soon. Now a team of entomologists from the University of Rhode Island is fighting the invader with a predatory wasp from its native land in hopes that the region’s next generation of ash trees will survive.
        Lisa Tewksbury, director of the URI Biocontrol Laboratory, and her students have been on the lookout for the emerald ash borer for more than a decade, soon after it was first discovered in the United States in Michigan. Now that they know it’s here, they are deploying three species of parasitic
Emerald ash borer (USDA)

wasp from Asia that lay their eggs in the beetle’s eggs or larvae. When the wasp eggs hatch, the wasp larvae consume the beetle eggs and larvae from the inside.
        “The beetle doesn’t have any natural enemies in the U.S., so we’re reuniting it with its natural enemies from back where it came from,” said Tewksbury. “We’re using one organism to control another.”
        The parasitic wasps have been extensively tested to ensure that they will only prey upon emerald ash borers. They are being raised at a federal laboratory in Michigan and shipped to Rhode Island as pupae that are about to become adult wasps inside blocks of ash wood, which the URI team delivers to areas where the beetle has previously been found. Once there, the wasps will emerge and lay eggs in beetle larvae the ash trees nearby.
        Tewksbury has a permit from the U.S. Department of Agriculture to release the wasps in targeted locations to attack the beetle.
        Ash trees make up just two percent of forests in Rhode Island, but they are found extensively in parks and along streets throughout the state.
        “The emerald ash borer isn’t a huge concern for our forests,” Tewksbury said. “But it will be a concern to people who have ash trees in their yards and on their streets. There are a lot of them in Newport and Providence.”
        Last year, Tewksbury released the three parasitic wasps in Hopkinton, near where the beetles were first discovered, and this year they are being released in five additional locations in Burrillville and Cumberland. The last round of releases for this year are taking place this month, and ongoing statewide surveillance for the beetle will indicate where additional wasp releases may take place next year.
        Next year will also be the beginning of an effort to determine if the wasps have become established and are doing their job. Tewksbury will peel back the bark of dead and dying ash trees to see if she can find evidence of dead beetle larvae.
        “We are resigned to that fact that we’re going to lose most of our larger ash trees, but by doing this biological control effort we’re hoping the wasps can protect the smaller trees so we’ll have some ash left in the future,” Tewksbury said.
        Targeted biocontrol efforts such as this are often the most cost-effective and least damaging way of fighting invasive insects. Tewksbury’s lab is involved in testing another predatory wasp for possible future deployment against what she expects will be the state’s next harmful pest, the spotted lanternfly, another tree-killing invasive species from Asia that is expected to arrive in Rhode Island in two or three years.

Monday, September 14, 2020

New disease is killing beech trees

        A University of Rhode Island scientist said that a disease that can kill beech trees was discovered in southwest Rhode Island in June, and both American and European beech trees throughout the region are at risk.
        According to Heather Faubert, who coordinates the URI Plant Protection Clinic, beech leaf disease was first identified in Ohio in 2012, and it spread to Pennsylvania, New York and Connecticut before arriving in Rhode Island. The disease damages a tree’s leaves, causing them to fall off. The energy
Beech tree leaves with beech leaf disease
required to regrow leaves stresses the trees, and if it happens several years in a row, the trees could die.
           “It’s really sad that it’s arrived here because beeches make such beautiful forest trees,” Faubert said. “Beech forests are stunning, their bark is gorgeous, and in fall their leaves turn a beautiful coppery color.”
        She said the disease is caused by a nematode, a microscopic worm that feeds inside the leaves.
        “It’s very easy to see if a tree is infected,” Faubert said. “If you hold a leaf up to the sun and you can see dark bands running parallel to the veins of the leaves, that’s the sign of an infected tree.”
        No treatment for the disease is available, as nematodes are difficult to control in the forest environment, but research is underway to identify treatments for individual landscape trees.
        “That’s the worst part; we don’t know what to do about it yet,” said Faubert, who observed diseased trees in an extensive area of beeches in Ashaway but did not find it in beech forests in Portsmouth or Middletown. “We also don’t know how it’s being transmitted from tree to tree, so if people walk around in the area of diseased trees, they should probably wash the bottom of their shoes before going into another forest.”
        She also advises that residents avoid digging up beech tree saplings from one forest and transplanting them elsewhere so as not to move potentially diseased trees to uninfected areas.
        Those who believe they have beech trees infected with beech leaf disease should take a photo and report it on the Rhode Island Department of Environmental Management’s invasive species pest report form.

Saturday, September 12, 2020

Identifying some wildlife is now a snap

        If you’re at all like me, whenever you see an animal or plant you’ve never seen before – be it a bug, bird, bat or begonia – you want to know what kind of living thing it is. You want to put a name to it. You want to know what to call it so you can tell your friends and family what you saw.
        That’s my immediate reaction every time, and it’s not unusual. Everybody does it, though not necessarily always with wildlife. For some people, they react the same way when seeing a car they’ve never seen. They need to know what make and model it is. While I can’t tell the difference between most cars these days, I’m always impressed by those who can distinguish them by tiny characteristics like taillights or bumpers.
        Where do you turn when you want to identify wildlife you’ve never seen before? Most of my friends turn to me. I get text messages and email messages almost daily from people who want me to help them identify something they got a brief glance at. If they send me a picture, I can usually help them. But often, the characteristics they claim to have seen don’t match up with anything that lives around here. Or they don’t notice the key distinguishing features of the specimen. With many species, you have to know what to look for to identify it correctly.
        But now that’s less of an issue, thanks to some extremely helpful free smartphone applications and websites that have turned identifying wildlife into a relatively simple experience. Most of the time.
        The Seek app is my favorite. Wave your phone over a plant or insect or turtle, for instance, and it quickly identifies it for you. That’s been a huge help whenever I see an interesting plant that I know I should know or a strange bug perched on my deck. It’s not so good for creatures that won’t sit still long enough for you to wave your phone in front of them, like birds and butterflies, or for animals you can’t get close to, like mammals. But for those that cooperate, it quickly solves the identification puzzle.
        When I wrote in July about identifying more than 250 species of wildlife in my backyard in 24 hours, it was mostly due to the Seek app that I was able to do so. I can confidently identify birds and mammals and amphibians, but insects and plants have always been a challenge for me, and close to 200 of the species I identified that day were plants and insects. It wouldn’t have been possible without Seek.
        For wildlife that you can photograph from a distance but can’t get close enough to use Seek, including birds, dragonflies, butterflies, bees and mammals, post your images to iNaturalist – either the website or app – and it will identify it for you. The Google photos app does something similar by comparing your photo to other online images (it will even identify cars).
        You can also get identification help for certain categories of wildlife at eBird, BugNET, eButterfly, Odonate Central (dragonflies) and similar online sources.
        Since I’ve started telling people about Seek and these other apps, I don’t get nearly as many texts and emails asking for my help identifying things as I used to. Now I seldom hear from anybody at all.
        As one so-called friend jokingly said, “Now that I’ve got Seek, what do I need you for?”

This article first appeared in the Independent on Sept. 3, 2020.

Friday, September 11, 2020

Dragonfly predation on eastern newts

Eastern newt (Elise Tillinghast)
        Common green darners are among the largest dragonflies in the Northeast, and they are voracious predators, capturing large flying insects – including other dragonflies – while in flight. During their long larval stage in freshwater ponds, they are equally predatory, feeding on aquatic insects, minnows, tadpoles, and even developing froglets.
        But whether they also feed on the larvae of eastern newts was unknown. Although newt larvae are similar in size to other green darner prey, newts also contain a neurotoxin that may make them unpalatable. So Brian Gall, a biology professor at Hanover College in Indiana, conducted a series of laboratory experiments to determine whether darner larvae will eat newt larvae and whether the newts employ any behavioral strategies to avoid being eaten.
         The palatability question is particularly complex, as it is unknown how much neurotoxin the newts contain in larval form. Adult newts have only low levels of the toxin, and Gall said they are known to deposit some of their toxin in their eggs, but is it enough to repel green darner larvae? Juvenile newts – called efts – contain high levels of the toxin, even though it is believed that they are unable to produce it themselves.
        In the first experiment, green darner larvae were provided newt larvae in all three developmental stages to determine which was preferred. “They ate them all,” Gall said. “Young ones were eaten, old ones were eaten, and metamorphs were eaten. That was a surprise.”
        Next he assessed the survival rate of newt larva when exposed to dragonfly larva in environmental chambers. In two experiments, the dragonfly larvae ate 19 of 20 newt larvae. Because newt larvae rely on their sense of smell to detect predators, Gall then placed newt larvae in water previously containing green darner larvae, and it became clear that the newts could smell the dragonflies. They immediately slowed down their movements.
        “Even though they don’t have enough toxin to protect themselves, the newt larvae have behavioral mechanisms to help keep them safe,” Gall explained. “When they smell a dragonfly, they reduce their activity and hide by sitting at the bottom of a pond until they don’t smell that dragonfly anymore.”
        Given how voraciously common green darner larvae prey on newt larvae in controlled experiments, one might think that the newts may struggle to survive in the wild. But Gall isn’t worried about them. “I’m sure the dragonflies are eating a lot of newt larvae, but every fall we find thousands of developing efts, so the dragonflies aren’t getting close to eating all of them. The newts have evolved mechanisms to survive.”
        Still, he’s curious how the relationship plays out in the wild. “Newts aren’t confined in a little dish with nothing to hide them,” he said. “I’d like to look at mortality rates in the field and understand how successful dragonfly larvae are in the wild when they have other things to eat. How likely are newt larvae to survive in those conditions?”

This article first appeared in the fall 2020 issue of Northern Woodlands magazine.

Tuesday, September 8, 2020

Bay warming causes seasonal shift in jellyfish-like creatures

        Nearly 50 years of weekly surveys in Narragansett Bay have revealed changes in the seasonal activities of ctenophores – small, non-stinging, jellyfish-like creatures – that have implications for the health of fish populations in the bay.
        Scientists at the University of Rhode Island and Rutgers University report in the Journal of Plankton Research this month that while numbers of the ctenophore Mnemiopsis leidyi have not increased, as had been speculated, higher temperatures in the bay have led them to be more prevalent earlier in the spring and later in the fall than previously observed.
        And because they feed voraciously on copepods – zooplankton near the bottom of the food chain, upon which many young fish feed – they are likely limiting the amount of food available to larval fish
Ctenophore by Michael Salerno

. Ctenophores also eat fish eggs and some larval fish, which also could affect fish populations.
        Barbara Sullivan-Watts, emerita marine research scientist at URI’s Graduate School of Oceanography and an adjunct professor of biology at Providence College, who manages the survey data, calls ctenophores “big bags of water that aren’t terribly nutritious, so very few predators will eat them.” Rather than using venom to capture prey, they use sticky cells like flypaper to subdue potential victims. They propel themselves by waving tiny comb-like cilia – hence their nickname, comb jellies – and they are bioluminescent, which makes them glow in warm temperatures.
        The animals have been collected from the same location in Narragansett Bay nearly every week since 1972 using a cone-shaped net that is pulled by hand from the bottom of the seafloor to the surface. The work was started by the late Ted Smayda, an international expert on plankton at the Graduate School of Oceanography, and continued by Sullivan-Watts. It is one of the longest-running quantitative plankton studies in coastal waters around the globe.
        Ctenophores do not feed or reproduce until water temperatures approach 50 degrees Fahrenheit, and their activity levels and reproduction rates increase as temperatures rise through mid-summer. In the first decades of the survey, that meant the peak of their reproduction – or what scientists call a bloom – was in July. But now, after years of increasing temperatures, their blooms occur many weeks earlier. In recent years, they have also had a second bloom in early fall.
        “They’re dormant and slow and lazy in winter, but once conditions get favorable and the ecosystem begins ramping up with phytoplankton blooms and copepods increasing, that’s when ctenophore abundance increases and they’re rapidly feeding. That’s when they start to reproduce,” said Emily Slesinger, a doctoral student at Rutgers who analyzed the data. She participated in the data collection in 2014 while, as an undergraduate at the University of California at Santa Cruz, spending the summer at URI.
        “In winter, they just hang around until they starve to death or disintegrate and disappear,” added Sullivan-Watts. “They stop reproducing in winter and spend that time in shallow embayments most years.”
        If ctenophores are active and reproducing for a longer period of time than they used to be, then why haven’t their numbers increased? The researchers aren’t certain.
        Sullivan-Watts said that it could be because of the 50 percent reduction in nutrients being discharged into the bay from wastewater treatment plants since 2005. That may have affected the abundance of phytoplankton, limiting food available to zooplankton like copepods, and ultimately decreasing the availability of food to ctenophores. The scientists have detected a slight decrease in the abundance of ctenophores in the bay in the last few years, which may be the result of this cascade of events.
        While that cascade has not yet been proven, what is known is that some species of copepods that used to be abundant in Narragansett Bay are now less common because so many are eaten by ctenophores.
        “It appeared that the copepods might suffer a permanent decline,” Sullivan-Watts said. “More data is needed to determine if the copepods are also changing their seasonality to escape predation by the ctenophores.”
        Yet despite the changes in the timing of ctenophore activity and their impact on copepods and fish, Sullivan-Watts said she isn’t sure there will be a long-term impact on the bay ecosystem.
        “It’s not a catastrophe; it’s just a change,” she said. “We don’t really know how this change perpetrates itself on other elements of the food web.”
        The introduction of the ctenophore to European waters has not been as benign, however. Beginning in the Baltic Sea in the 1980s and spreading elsewhere, they reproduced explosively and contributed to the collapse of fisheries throughout the region.
        To get a clearer picture of their impact in Narragansett Bay will require the continuation of the long-term data collection on which the new research is based.
        “Time-series studies like this are tremendously important to tracking our environment,” said Sullivan-Watts. “If you don’t have people continuously taking data the same way year after year, you don’t know what has changed.”

        This article first appeared on EcoRI.org on Septemnber 8, 2020.

Wednesday, September 2, 2020

Researchers track groundwater discharges into salt ponds

        The movement of groundwater in aquifers deep beneath the surface often carries with it a variety of contaminants that can be traced to leaking septic systems, damaged underground infrastructure, excessive fertilizer use and other land uses. But where that groundwater and those contaminants end up is often unknown.
        Using a drone with an infrared thermal imaging camera, a team of University of Rhode Island researchers led by doctoral student Kyle Young has tracked some of it to the Ocean State’s coastal ponds.
        “We’re looking to quantify the amount of nutrients being brought into our estuaries and what’s happening to those nutrients,” said Young, a Coast Guard helicopter pilot and physics teacher at the
Coast Guard Academy on leave to earn his doctorate. “The key nutrient is nitrate. In small amounts, nitrate is a good thing, but in larger amounts it can be degrading to the ecosystem.”
        Young and his advisor, URI Associate Professor Soni Pradhanang, seek to quantify the discharge of groundwater into the salt ponds as part of an analysis of what they call a “water budget” or an accounting of all of the water that flows into and out of the area.
        “We know the amount of precipitation that comes down, we can quantify how much runoff goes into stream water, but one thing that’s not easy to directly quantify is groundwater flow,” said Pradhanang. “We don’t know how much water is going from the aquifers into other water bodies.”
        Since the temperature of groundwater is cooler than the salt ponds in late summer, a drone equipped with an infrared thermal imaging camera can detect a plume of cool water in the ponds that is likely a discharge of groundwater. And that’s exactly what Young and Pradhanang Lab graduate student Jeeban Panthi and undergraduate Janelle Kmetz have found at Green Hill and Ninigret ponds.
        They flew their $10,000 drone at 400 feet over miles of salt pond coastline and captured several infrared images showing significant cool zones suggesting that groundwater is entering the pond from the bottom. Because groundwater is freshwater and less dense than the saltwater in the ponds, it rises to the surface, delivering a clear signal to the infrared camera.
        “Just because we don’t see plumes in some areas doesn’t mean there isn’t groundwater discharge there, too,” noted Young. “There could be too small of a freshwater component for it to show up in the thermal signature, or it might not be cool enough compared to the surrounding water. But one thing we can say about the plumes we found is that they have ample freshwater, signifying waters that came from the terrestrial zone.”
        What that means for the health of the coastal ponds is uncertain. Discharges such as those the researchers found have likely been going on for many years, and groundwater doesn’t always contain contaminants. But identifying their locations may be useful in tracking the movement of terrestrial pollutants into the ponds in the future.
        The discovery also has implications in the context of climate change. According to Pradhanang, the groundwater affects the salinity and pH of the pond water, which is critical to many water activities like aquaculture, as well as to the plants and animals that live in the ponds.
        If storm surges happen more frequently, as is predicted with climate change, they might affect the amount of groundwater entering the water bodies, changing the environmental conditions and negatively affecting the wildlife that lives there. “It could have implications at an ecosystem level,” Pradhanang said.
        Now that the plume locations have been identified, Young is continuing his drone flights to see how the weather and tides affect the plumes.
        “Flying highly sensitive equipment on an aircraft is high stakes research,” he said. “Quantifying how the discharge changes over time is the next step. But so far it’s nice that we’ve been able to identify the sites of possible pollution contribution to the ponds.”
        Once Young returns to the Coast Guard Academy next year, Pradhanang hopes future students will take up the project to identify groundwater discharge locations and quantities into other salt ponds, coastal and freshwater bodies, Narragansett Bay, and elsewhere around the region.