Monday, December 17, 2018

Researcher: Oyster aquaculture limits disease in wild oyster populations

                A fisheries researcher at the University of Rhode Island has found that oyster aquaculture operations can limit the spread of disease among wild populations of oysters. The findings are contrary to long-held beliefs that diseases are often spread from farmed populations to wild populations.
                “The very act of aquaculture has positive effects on wild populations of oysters,” said Tal Ben-Horin, a postdoctoral fellow at the URI Department of Fisheries, Animal and Veterinary Sciences in the College of the Environment and Life Sciences. “The established way of thinking is that disease spreads from aquaculture, but in fact aquaculture may limit disease in nearby wild populations.”
                Working with colleagues at the University of Maryland Baltimore County, Rutgers
Oyster farm in Delaware Bay (Tal Ben-Horin)
University, the U.S. Department of Agriculture, and the Virginia Institute of Marine Science, Ben-Horin integrated data from previous studies into mathematical models to examine the interactions between farmed oysters, wild oysters and the common oyster disease Dermo.
Their research, part of a synthesis project at the National Center for Ecological Analysis and Synthesis, was published this week in the journal Aquaculture Environment Interactions.
                According to Ben-Horin, diseases are among the primary limiting factors in wild oyster populations. There are few wild populations of oysters in New England because of Dermo and other diseases, and in the Chesapeake Bay and Delaware Bay, wild oysters are managed with the understanding that most will die from disease.
                Dermo is caused by a single-celled parasite that occurs naturally in the environment and proliferates in the tissue of host oysters, which spread the parasite to other oysters when they die and their parasite-infected tissues decay in the water column. But it takes two to three years for the parasite to kill the oysters. As long as the oysters are held on farms long enough to filter disease-causing parasites from the water, but not so long that parasites develop and proliferate and spread to wild oysters nearby, aquaculture operations can reduce disease in wild populaitons.
                The disease does not cause illness in humans.
                “As long as aquaculture farmers harvest their product before the disease peaks, then they have a positive effect on wild populations,” Ben-Horin said. “But if they’re left in the water too long, the positive effect turns negative.”
                He said that several factors can confound the positive effect of oyster aquaculture. Oyster farms that grow their product on the bottom instead of in raised cages or bags, for instance, are unlikely to recover all of their oysters, resulting in some oysters remaining on the bottom longer. This would increase rather than reduce the spread of the disease.
                “But when it’s done right, aquaculture can be a good thing for wild oyster populations,” Ben-Horin said. “Intensive oyster aquaculture – where oysters are grown in cages and growers can account for their product and remove it on schedule – is not a bad thing for wild populations.”
                The study’s findings have several implications for the management of wild and farmed oysters. Ben-Horin recommends establishing best management practices for the amount of time oysters remain on farms before harvest. He also suggests that aquaculture managers consider the type of gear – whether farmers hold oysters in cages and bags or directly on the seabed – when siting new oyster aquaculture operations near wild oyster populations.     
The next step in Ben-Horin’s research is to gain a better understanding of how far the Dermo parasite can spread by linking disease models with ocean circulation models.
                “Everything that happens in the water is connected. There’s a close relationship between the wild and farmed oyster populations and their shared parasites,” he said. “Sometimes ecosystem level effects are overlooked, but in this case they’re front and center.”

Sunday, December 9, 2018

Outlook dismal for rebuilding region's winter flounder stocks

            Winter flounder is one of the most popular fish among recreational anglers and commercial fishermen, due in part to their thick fillets and great taste. Once abundant in Rhode Island waters, their numbers have declined significantly in recent decades, and new research suggests that the warming climate will likely make it impossible to rebuild their stocks to targeted levels.
            The study, led by a former research associate at the NOAA Northeast Fisheries Science Center in Narragansett, concluded that even if fishing were to be curtailed entirely, winter flounder populations are unlikely to rebound.
            According to Rich Bell, who now works as a fisheries scientist for The Nature Conservancy, winter flounder is a cold-water, coastal species that spawns in estuaries like
Winter flounder (Jerry Prezioso/NOAA)
Narragansett Bay and Buzzards Bay during the fall and winter when most other flounders migrate south or offshore. Their eggs and larvae develop in the estuaries during the coldest months of the year.
            “During the 1980s and 90s they were overfished, and it seems that they never really recovered,” said Bell. “We believe that they come into the bays to spawn in winter where they have a thermal refuge from predation. When it’s cold, there are no predators around, giving them time to grow big enough before it warms up and the predators arrive.”
            The concern is that as the climate has warmed and spring arrives earlier and earlier, the predators are now arriving before the larvae have a chance to grow big enough to escape. Common predators on larval winter flounder include sea robins, summer flounder, sculpins and crangon shrimp.
            By combining winter flounder population models with climate models, Bell and his NOAA colleagues projected future population numbers as the climate continues to heat up. They factored in three fishing scenarios into their models: no fishing, moderate fishing representing a small fishery or incidental catch, and fishing at the expected long-term sustainable level assuming the stock was rebuilt to historic levels.
            “We found that as temperature increases, it’s going to be more challenging for the population to recover. And more importantly, even if there is no fishing and the temperature goes up as expected, they may be unable to reach the targeted recovery level,” said Bell.
            A large part of the problem is that winter flounder produce fewer young in warm waters. The species is now rarely caught in southern estuaries like Chesapeake Bay, and numbers are way down in Delaware Bay and Long Island Sound.
            “There might be so few in Long Island that there are subtle signs of inbreeding occurring,” he said.
            Bell notes that winter flounder are not headed toward extinction. Populations are healthy in colder water regions like the Gulf of Maine, Georges Bank and the Canadian Maritimes. But the continuing declines in southern New England raise challenging questions for their management.
            “It becomes a larger issue of what do we as a society want to do,” Bell said. “Do we want to stop fishing them entirely? Do we want to fish them all now before they’re gone?”
            While Bell wasn’t willing to weigh in on those questions, he said the phenomenon of cold-water fish species experiencing a decrease in productivity and an increase in mortality is not exclusive to winter flounder. Other researchers are documenting similar results in other species as ocean temperatures rise.
            Whether the target levels for rebuilding winter flounder stocks are even plausible is another question. Bell said that those targets are based in part on data collected in the 1960s and 70s before significant warming had occurred and when the species was reproducing at high levels.
            “Rebuilding plans developed assuming constant rates for demographic variables such as growth, reproduction and mortality may not be realistic for stocks like winter flounder,” he said.
The research was published in September in the Canadian Journal of Fisheries and Aquatic Sciences. 

This article first appeared on EcoRI.org on December 7, 2018.

Friday, November 23, 2018

New testing system provides early warning of toxic algae blooms

            When a large bloom of harmful algae appeared in lower Narragansett Bay in October 2016 – and again in early 2017 -- the state’s testing methods were not refined enough to detect it before the toxins produced by the algae had contaminated local shellfish. That scenario is not likely to happen in the future, now that the Rhode Island Department of Health’s laboratories have acquired new instrumentation and analytical tests to detect the toxins early and to determine when they have dissipated enough so shellfish harvesting may resume.
            “It’s an improved early warning system so we don’t have to worry about future problems with harmful algae blooms,” said Henry Leibovitz, the chief environmental laboratory scientist at the Department of Health. “We’re trying to safeguard public health, safeguard our shellfish economy, and safeguard the state’s shellfish reputation.”
            The new testing system was approved in September by the Food and Drug Administration’s National Shellfish Sanitation Program, which regulates the interstate sale of shellfish.
            The 2016 and 2017 blooms, which Leibovitz said were the first harmful algae blooms to occur in Narragansett Bay, forced the closure of parts of the bay to shellfishing and required that some previously-harvested shellfish be removed from the market. It was caused by the
Pseudo-nitzschia (Rozalind Jester)
phytoplankton Pseudo-nitzschia, which, when concentrated in large numbers, can produce enough of the biotoxin domoic acid to contaminate shellfish and cause those who eat the shellfish to contract amnesic shellfish poisoning.
            Another kind of plankton, Alexandrium, produces a biotoxin that can cause paralytic shellfish poisoning. Both Pseudo-nitzschia and Alexandrium occur in Rhode Island waters year-round, but they are only harmful when concentrations are high and the toxins they produce reach 20 parts per million.
            According to Leibovitz, the state’s previous testing system was “a primitive screening test” somewhat like a pregnancy test – it could determine whether the toxins had reached the limit, but not how far over or below that threshold they were. And it was not sensitive enough to detect the lower concentrations of the toxins that would signal that the bloom had dissipated and shellfish harvesting could begin again. To reopen shellfish beds to harvest, the state had to send water and shellfish samples to a private laboratory in Maine, the only lab in the country capable of conducting the test at the time.
            Now that Rhode Island has an FDA-approved lab, it is offering its services to nearby states.
            The state's Harmful Algae Bloom and Shellfish Biotoxin Monitoring and Contingency Plan directs the Rhode Island Department of Environmental Management to collect weekly water samples from areas of the bay where shellfish are harvested. The samples are tested in the Department of Health lab. If large numbers of harmful algae species are found, the plankton are tested to determine the concentration of toxins they are producing. If toxin concentrations are high, shellfish are then tested and a decision is made whether to close particular areas to harvesting.
            The problem of harmful algae blooms has been an annual concern along the coast of Maine for many years, and scientists speculate that it could be a more frequent problem in southern New England in coming years, too.
            “We think the problem is knocking on our door,” said Leibovitz, “and we need to be prepared for it, not only for public health but to protect our strong shellfish economy. Imagine the damage that would occur to our reputation if contaminated shellfish was identified as coming from Rhode Island. People have a long memory for something like that.”
            Public awareness of the risk from harmful algae blooms was raised this year as a result of the months-long red tide in Florida, which killed fish and marine mammals and sickened many people. It was the result of a bloom of a plankton species that produces a toxin called brevetoxin, causing neurotoxic shellfish poisoning in people who eat infected shellfish.
            What triggers the algae to bloom is what Leibovitz calls “the $60,000 question. A lot of people are studying it, including some at the University of Rhode Island, and there are a lot of theories behind it, but there’s nothing conclusive. There’s speculation that the cleaner bay means that the harmful species don’t have the competition that they used to have, but that hasn’t been proven,” he said.
            The bloom of harmful algae in Narragansett Bay in 2016 and 2017 led Rhode Island Sea Grant to fund research to try to answer some of the questions raised by the bloom. Researchers from URI and elsewhere are investigating whether bacteria that accompany the plankton may influence the amount of domoic acid produced; whether nitrogen from the sediments may fuel the blooms; and whether nutrients from outside the bay played a role.
            “The fact that we had our first harmful algae bloom doesn’t mean we’ve had our last,” concluded Leibovitz, “not with it happening every year in Maine. But now we’ll be way ahead of the curve in recognizing when there’s a problem developing.”

This article first appeared on EcoRI.org at November 23, 2018.

Monday, November 19, 2018

Bird feeders attract bird eaters

            As much as I love wildlife documentaries on television, I always get queasy when they focus on predators like lions and hyenas.  I love learning about the life cycle and behavior of these amazing creatures, but I have a difficult time watching as one beautiful animal catches and tears apart another beautiful animal.
            Yet it’s not just on TV that I watch this happen. It happens all the time around my bird feeders in my backyard, too.
            We often think of bird feeding as a hobby that benefits the birds. And it is.  But some of the birds that it benefits are hawks that feed on other birds. That’s because some hawks have discovered that active bird feeders – with their unnatural abundance of wildlife – are an easy place to find a snack. 
            Occasionally when I glance out the window at my feeders to see who is about, there is an
Cooper's hawk at a bird feeder (H. Gilbert Miller)
unusual scarcity of birds. And the birds that are visible often look like miniature statues, frozen in place for long minutes at a time.  It’s during these tense moments that I know a hawk is nearby.
            It’s usually a Cooper’s hawk, whose narrow wings and long tail enable it to maneuver quickly through the forest and capture fast-moving prey like songbirds. And their affinity for small birds is why they appear at bird feeders so often.
            Glancing out my back window last week, I saw a burst of motion out of the corner of my eye. Appearing as if out of nowhere, a Cooper’s hawk swooped over the roof and dove at my feeders like a stealth bomber.  In that brief moment, the congregating songbirds were forced to make a life or death decision – should I fly away and hope to outrun the intruder, or should I freeze in place and hope it doesn’t see me.
            Those that froze made the better decision.  A male nuthatch stopped in its tracks on the trunk of a maple tree, head pointed downward like he was about to tumble to the ground. A like-minded downy woodpecker was perfectly positioned on the underside of a branch and out of view of the marauding hawk.  And a tufted titmouse appeared to me to be in full view but was ignored or unnoticed by the hawk.
            The rest of the birds that had been at the feeders took off in a storm of feathers and alarm calls, probably hoping that the hawk was homing in on one of the others.  A flock of goldfinches at the thistle feeder flew away en masse to confuse the hawk in a tornado of yellow and black bodies. But one goldfinch reacted just a little slower than the others. That’s the bird the hawk targeted, and that’s the bird the hawk ate for breakfast.
            I know that many people are uneasy when a hawk is seen around their feeders, and they want to discourage the predators from visiting. But hawks have to eat too, and they play an important role in the food chain by consuming the ill and injured. So it’s better if we simply appreciate the opportunity to get a close-up look at wildlife doing what wildlife does. Like when we watch those public television documentaries.
            It was about ten minutes before the nuthatch and the woodpecker and the titmouse felt safe enough to move again.  And soon after, the goldfinch flock returned to the thistle feeder. To them, it was just another day.

This article first appeared in the Independent on November 15, 2018.

Saturday, November 3, 2018

Upper bay fish survey yields surprising results

            Due to the historically degraded water quality in upper Narragansett Bay, the fish that spend all or part of their lives there have seldom been studied. But as improvements have been made to the wastewater treatment plants in the area and the water quality has improved in recent years, more and more recreational fishermen have been observed reeling in a variety of fish species.
So The Nature Conservancy teamed with the Rhode Island Department of Environmental Management to conduct a baseline study of fish found from Conimicut Point in Warwick to the Pawtucket boat ramp on the Seekonk River. And the results have been somewhat surprising.
William Helt, a coastal restoration scientist at the Rhode Island office of The Nature
Conservancy who is leading the project, said the survey is an effort “to learn what fish are using that area and what the residence times are for those species. We want to get a gauge for how these sites compare to other areas in Narragansett Bay that are considered the healthy parts of the bay.”
Once a month from May to October, Helt and a team of scientists and volunteers visit 12 coastal sites, including Gaspee Point in Warwick, Sabin Point in East Providence, and Stillhouse Cove in Cranston, to survey for fish.
Using a beach seine net – a 130-foot long net with weights at the bottom and floats on top – one member of the research team holds an end of the net on shore while a boat deploys the rest of the net and drags it in a semi-circle back to shore. Any fish collected are counted, identified and released.
“We’re looking at the estuary as a nursery habitat for juvenile fish, so most of the fish we’re catching are about the length of your finger,” Helt said.
The researchers also used fish pots – similar in size and design to a lobster trap – to target larger fish like black sea bass.
While the data has yet to be analyzed or compared with the results from similar surveys in the lower bay and South County’s salt ponds, Helt said they have captured large numbers of bait fish like silversides, mummichogs and killifish. One day at Sabin Point they captured about 140,000 menhaden at one time.
“That means there’s a lot more fish utilizing the upper bay than we thought,” he said.
The net catches juvenile fish popular among local anglers as well, like tautog, winter flounder and scup. And at the mouth of the Seekonk River it collected freshwater species, including white perch and bluegill. It even caught some unexpected southern species like pufferfish and pipefish.
“We haven’t caught as many scup as we thought we would,” Helt said. “They might tend not to favor the close-to-shore habitat that we’re sampling. But we see so many people fishing for scup that we thought we’d catch more.”
Helt would have preferred that the study had started several years earlier to detect how fish populations changed as water quality improved, though he anticipates continuing the project for many years in order to assess changes to fish populations due to warming waters and further improvements to water quality.
The project may also get extended beyond the May-to-October time frame of the first two years.
“That’s when juvenile fish activity is highest; most migrate out of the estuary by October or November,” Helt said. “But we’re seeing plenty of fish in May and October, so we’ve thought about extending it for a couple extra months.”
The data the scientists have collected so far has already got them thinking about habitat improvements that could be made in the upper bay to accommodate even larger numbers of young fish.
Assuming that permits can be secured from the Rhode Island Coastal Resources Management Council and other agencies, Helt said that The Nature Conservancy and DEM anticipate deploying 80 to 100 “reef balls” – four-foot diameter concrete structures with holes in them – just beyond the Sabin Point fishing pier.
“The reef balls tend to aggregate fish,” he explained. “They eventually get fouled with colonizing organisms that provide a food base for juvenile fish, and they provide structure for small fish to hide in. We hope they’ll improve that critical life stage of juvenile fish and attract sport fish that people like to catch.”
The reef balls will likely be deployed in 8 to 10 feet of water just beyond the casting range of recreational fishermen.
The fish survey results may also lead to efforts to improve salt marsh habitat, which also plays an important role in nurturing juvenile fish.
“And in the salt ponds we’ve been studying the use of oyster shell reefs to improve fish habitat. We might do a similar project in the upper bay,” Helt said. “But we’ve got a lot of hurdles to overcome between now and then. That’s a long-term goal.”
The fish survey and subsequent habitat restoration projects are being funded by the U.S. Fish and Wildlife Service’s Sport Fish Restoration Program.

This article first appeared on EcoRI.org on November 2, 2018.

Tuesday, October 30, 2018

Cutting bacteria's cell service

            Scott Ulrich is working to create a drug that disrupts the communication system that bacteria use to coordinate disease-causing behaviors, and he was just awarded a major grant from the National Institutes of Health to help him do it.
            The Ithaca College associate professor of chemistry will use the three-year $360,000 grant to design complex molecules that will block the communication system known as quorum sensing.
            “Bacteria communicate with each other using chemical signals,” explained Ulrich. “When their signaling is engaged, the population undertakes a new behavior. Sometimes that behavior causes diseases in people. If we can block that signaling, then the behaviors the signaling controls would also be suppressed. I want to accomplish that by creating a drug-like inhibitor.”
            Ulrich has been studying quorum sensing for more than a decade. In his previous work, he and two students – in collaboration with scientists from Princeton University – created a drug that blocked the bacterial signal detector, essentially making the bacteria deaf so they did not know that other bacteria were trying to communicate. Now he is attempting to render the bacteria mute by preventing their ability to generate a communication signal in the first place.
            “This is a very hard thing to do. Few other chemists have found such drugs,” he said. “Several IC students and I have worked without much success since 2010 to set up the biochemical system needed to find such compounds. I was ready to give up.”
            Then came Erin Higgins, a biochemistry student who insisted on working on the project last year despite Ulrich’s repeated advice not to.
            “She re-created the signal generation system in a test tube using purified bacterial proteins, and it actually makes the signaling molecule,” he said. “Now we can add candidate drugs to the system to see if they block the process of making the signal. It’s the most impressive work I’ve ever seen an undergraduate do. Her results led directly to the grant and serve as the foundation for the work my students and I will do for many years.”
            There is still plenty of difficult work ahead. Ulrich said that the enzyme that produces the communication signal provides clues to the kind of organic structures that might block the system from working. And he already has some designs in mind. So his students will spend the next three years building as many different kinds of molecules as they can and testing to see which ones are most successful at disrupting the bacteria from communicating.
            “The ideal outcome would be to find a molecule that blocks the quorum sensing signal production without requiring a large dosage,” Ulrich said. “Generally, more potent compounds work better against the intended target and are safer.”
            Assuming he succeeds at building an effective molecule, his next step would be to work with his Princeton collaborators to test the molecule to see if it inhibits the disease-causing behavior.
            “That’s the outcome we’re looking for,” he said.

This article first appeared on the Ithaca College News website on October 30, 2018.

Tuesday, October 23, 2018

Award-winning carver brings wooden birds to life

            When Ray Tameo was a young boy and his friends invited him to play baseball, he usually turned them down in favor of going birdwatching. The retired highway bridge designer from Attleboro later combined his passion for birds with his interest in duck hunting and began experimenting with carving duck decoys.
            Today, Tameo is an award-winning bird carver whose carvings are in numerous private collections and exhibited around the region. He will be one of a dozen carvers who will display their work at the Audubon Society of Rhode Island’s annual Bird and Wildlife Carving Exposition in Bristol on November 3 and 4 from 10 a.m. to 4 p.m.
            “I’m entirely self-taught, and the longer you’re at it, the better you get,” said Tameo. “The more you put into it, the more you get out of it.”
            Tameo’s carving evolved from duck decoys to small songbirds, which typically take him about 125- to 150-hours to complete. Working in his basement workshop or garage, depending
on the weather, he carves highly detailed birds perched in lifelike settings. His carvings are made almost exclusively from tupelo wood from Louisiana because of its light weight, absence of grain, whitish color and ease of carving.
            “It also takes paint beautifully,” he said.
            The first step, he said, is to draw the bird’s profile on the wood, then cut it out using a small band saw.
“From that, I put a centerline down the middle and start shaping the bird and cutting off excess wood. Then I use Dremel tools – a rotary tool – to start shaping it finer and finer. Once that’s done, I do relief carving.”
            For the final details, he uses an Exacto knife to give texture to the feathers and finishes with a burning tool. Painting the birds involves two coats of acrylic sealer and seven or eight layers of paint.
            “I’m very meticulous; I’m a perfectionist,” he said. “Down the road, I’m going to be long
gone, and my carvings are going to be in somebody’s house, so I don’t want to produce a mediocre bird. I want a bird that will last. It will speak for me when I’m gone.”
            Most of Tameo’s carvings are commissioned by clients and collectors he meets at exhibits like the Audubon show. One man in Bristol has purchased 17 of his shorebird carvings over the last five years.
            While he occasionally enters carving competitions or gives lessons to beginning carvers, Tameo said he’s too busy to focus on anything but the work his clients commission him to produce. He just finished painting carvings of an eastern bluebird perched next to an abandoned woodpecker hole and a Baltimore oriole on a maple tree branch. He even carved each maple leaf on the branch. Now he is in the early stages of work on a three-quarter size common loon and a life-sized black-capped chickadee and northern cardinal.
His most visible work, however, was done for Greg Esmay, the owner of the popular Old Grist Mill Tavern in Seekonk, which burned down in 2012 after a tractor trailer rolled over, slid into the building, and ruptured a gas line. Prior to the fire, the restaurant displayed Esmay’s extensive collection of antique duck decoys, most of which were damaged in the fire and subsequent demolition of the structure. Tameo restored 35 of them.
            “I put new heads on some, made other repairs on others, and I made them all look antique-ish again,” he said proudly. “Then he asked me to carve three Canada geese flying that I mounted on a piece of wood from the original restaurant.”
            The geese are now hanging over the rebuilt restaurant’s fireplace. Esmay purchased several original Tameo carvings as well, including a puffin and kingfisher.
            Out of all of his carvings, Tameo is most proud of his rendering of an eastern meadowlark perched on a barbed wire-wrapped fencepost, the bird’s head tilted back and its beak open wide as if in full song.
            “That’s my favorite,” he said. “I won’t part with that one.”
            The Bird and Wildlife Carving Exposition takes place at the Audubon Nature Center and Aquarium, 1401 Hope St., Bristol. In addition to the exhibition of finished carvings, some of the participants will demonstrate their carving techniques. For more information, visit www.asri.org or call 401-949-5454. Admission is $5.

This article first appeared in EcoRI.org on Oct. 18, 2018.