Saturday, August 18, 2018

Seeking seabirds between the swells

            Traveling aboard the University of Rhode Island research ship Endeavor earlier this month, I spent way more time than I probably should have staring out at the gray seas, scanning between the swells in search of birds. It’s my natural inclination when I’m in an unusual place – to watch for whatever birds or other wildlife may be about -- and many miles from land is indeed an unusual place.
            I was traveling with a group of local teachers and oceanographers, learning about ocean science as part of the Rhode Island Teachers at Sea program, which provides educators with an opportunity to get hands-on research experience that they can use to illuminate their classroom
Wilson's storm petrels (Dan Izirarry)
lessons. And as energizing as it was to cruise the high seas, deploy oceanographic instruments, and gain a better understanding of how science works, I frequently found myself with one eye on the horizon wondering if a rare seabird might be darting by as we were collecting data.
            The birds I was looking for were species that most people have never heard of – shearwaters, storm-petrels and jaegers.  These seabirds are unknown to but the hardiest of birdwatchers because they are almost entirely pelagic, spending nearly their whole lives far out at sea and only returning to land – mostly on inaccessible, uninhabited islands in the Southern Hemisphere – for short periods to breed.
            To get a good look at these remarkable creatures usually requires a lengthy boat trip 15 or more miles offshore, out to where the swells churn your stomach and land is nowhere in sight. So the Endeavor was the perfect platform to find them. At a spot between Block Island and Martha’s Vineyard called the Mud Hole, where the ship stopped to deploy some equipment, seabirds were everywhere.
            Mixed in among some gulls were hundreds of shearwaters, which always send my heart racing.  To the untrained eye, shearwaters look like dirty gulls.  But their stiff-winged flight just above the cresting waves gives them away.  They fly so close to the waterline that it’s easy to lose them as the waves rise and fall. 
            The most unusual part of a shearwater’s anatomy is its beak.  It appears to have tubular nostrils on the upper mandible -- hence their colloquial name “tubenoses.”  This odd growth is actually an adaptation that allows them to drink seawater and to rid their system of excess salt, since they never have access to fresh water. 
            Like shearwaters, storm-petrels are tubenoses, but that’s where their resemblance ends.  These robin-sized brown birds flit and flutter butterfly-like among the waves, often playing patty-cake with their feet on the water as they search for tiny edible morsels.  As their name suggests, storm-petrels tend to be most active and abundant in stormy, white-capped seas with gray skies.
            Then there’s the jaegers, perhaps the most unpredictable of the seabirds.  Sometimes they soar high overhead like a hawk or low to the water like a shearwater, and at other times they may initially go unnoticed and arrive with a flock of gulls. But they quickly give themselves away.
            For those who find the behavior of gulls or crows unappealing due to their aggressiveness and scavenging habits, you’ll definitely dislike jaegers.  They seldom find their own food, instead spending their feeding time harassing smaller birds into relinquishing their meal. 
            Far out to sea, beyond the reach of most of mankind, this behavior has allowed them to find a niche in the brutal oceanic world, and to flourish.  But at my dinner table, that’ll earn you confinement to your room.

This article first appeared in the Independent on August 16, 2018.

Thursday, August 9, 2018

Seabird die-off remains a mystery

            Aboard the University of Rhode Island research ship Endeavor during the first days of August, seabirds were abundant in the waters between Block Island and Martha’s Vineyard. The birds weren’t the focus of the trip – it was really about providing local teachers with an opportunity to get hands-on science experience through the Rhode Island Teachers at Sea program – but the birds couldn’t be ignored. They were constantly in view.
            Most were shearwaters, long-winged birds that skim the surface of the waves as they search for marine organisms on which to feed. And last year at this time, many were unexpectedly dying and washing up on beaches throughout southern New England and Long Island.
            The population appears to be healthy this year, but scientists have not yet figured out the cause of last year’s die-off.
            “We’re still trying to piece it together,” said seabird researcher David Wiley, research
Great shearwaters (istock)
coordinator at the Stellwagen Bank National Marine Sanctuary in Massachusetts. “We’re studying their livers to look at their toxicology to see if something killed them. And a team at Woods Hole is looking at birds caught as bycatch in gillnets. But we haven’t come up with anything definitive yet.”
            Scientists speculate that the birds, which breed on islands in the South Atlantic and migrate to the East Coast in summer, arrived in local waters last year in such poor physical condition that they could not survive. Whether that is because of a lack of food or an accumulation of toxins or something else entirely is unknown.
            “It could be something here [in the North Atlantic] as well,” Wiley said. “It could be a toxic algal bloom that’s caused the problem here. That’s another thing to look into. But right now, it’s all speculative.”
            Although few birds have been found dead in the region this year, Wiley and a team of scientists hope to find some answers in a continuing study of great shearwaters, the most common of the shearwaters in the region, that began in 2013. Each year they capture 10 shearwaters and place satellite tracking tags on them to monitor their movements. The researchers hope to learn how and where the birds spend their time in the region.
            To capture the birds, they toss bait into the water from a small boat, and they use a hand-held net to catch any birds that get close enough to reach. They then weigh and measure the shearwaters, place a band around a leg, take blood and feather samples, and release them back into the wild.
            So far their research has confirmed that the most important feeding area for the birds is in the Great South Channel, a deep-water site east of Chatham, Mass. Unfortunately, the area is also an important commercial fishing destination, where hundreds of the birds are caught and drown in gillnets each year, mostly in August and September.
            “Everybody is eating sand lance – the birds, the whales, the fish – so that’s where the fishermen go, too,” Wiley said. “Sand lance is the key to the southern Gulf of Maine.”
            A tiny eel-like fish, sand lance are a favorite food of humpback whales, sharks, cod and other ocean predators. They spend their nights buried in the sand on the seafloor. Their cyclical population abundance drives changes in populations of the species that prey on them. And when sand lance numbers are high, conflicts arise between the whales, birds, fish and fishermen.
            The scientists are trying to figure out how to reduce the fishing by-catch of shearwaters, but they have had little success to date. The fishermen bait their nets to attract dogfish, and the baiting attracts the birds. If they don’t bait their nets, the nets must remain in the water longer as the fishermen wait for the fish to arrive, which increases the likelihood the nets will capture or entangle whales, porpoises and other marine mammals.
            Four years of data from 40 great shearwaters has confirmed that the birds move around a great deal, making it difficult to employ management strategies to protect them.
            “Some static management measures like marine protected areas may not be as effective as they used to because the ocean is changing,” Wiley said. “We may be able to use our satellite tagged birds to look at where the hot spots are occurring in almost-real time. Then management can be as dynamic as the oceans themselves. We’re trying to get ahead of the curve to see if there are other ways of managing the ocean.”
            URI doctoral student Anna Robuck is examining the birds from a different perspective. She is conducting toxicology tests of the birds to determine whether they are contaminated with any of a long list of chemical compounds, from long-banned pollutants like DDT and PCBs to such industrial compounds as flame retardants and perfluorinated compounds, which are used as water repellents and in non-stick cookware and many other consumer products.
            While she expected to find some of the contaminants in the birds’ tissues, including DDT, which is ubiquitous in the ocean, she was surprised to find some of the more than 4,000 perfluorinated compounds in the seabirds at similar concentrations to those found in gulls that live in Narragansett Bay.
            “That was totally unexpected,” Robuck said. “The shearwaters live in the remote South Atlantic, so we weren’t sure we were going to be able to detect measurable concentrations, because we were uncertain that the compounds would be found in the oceanic environment. They’re found in surface water in Narragansett Bay at much higher concentrations than offshore, so we’re not sure why they’re in the seabirds.”
            Birds in the bay are contaminated with a different set of perfluorinated compounds than those in offshore waters, which suggests to Robuck that the compounds are finding their way to the offshore environment via the atmosphere.
Nonetheless, she isn’t convinced that the contaminants have anything to do with the mass mortality of shearwaters last year.
            “The contaminants aren’t lethal in the way we saw happening to the birds last year,” she said. “No way was it related to their contaminant burden. There are so many variables at play. I thought we’d test for something and figure it out pretty quick, but it’s turned into something much more complex.
            “It’s probably an interplay of a lot of things – oceanographic conditions, food, stress from climate change,” Robuck concluded. “It’s a lot of stressers adding up. It’s really sad to see.”

This article first appeared on EcoRI.org on August 9, 2018.

Monday, August 6, 2018

Trawling for insights into a changing bay

            After dropping an oceanographic measuring device over the side of the Cap’n Bert, a University of Rhode Island research boat, Joe Zottoli records data about water temperature, salinity, and dissolved oxygen levels between Fox Island and the northwest shore of Jamestown. Then he and Captain Steve Barber deploy a small commercial fishing net behind the vessel and tow it along the floor of Narragansett Bay for 30 minutes. After covering approximately one mile, they haul the net back in, dump their catch on deck, and sort the animals by species into colorful baskets.
It’s a process they undertake twice every Monday throughout the year to sample the changing composition of marine life in the bay, a research project that began in 1959 and has revealed a great deal about how the bay has changed from season to season and year to year.
            An early spring storm brought poor visibility and rough conditions, but the first tow turned up some species finally on the move after a chilly winter. The season’s first spider crabs
 and horseshoe crabs were among the dozen species in the net, a sign that the crustaceans were returning to the bay after wintering in deeper waters offshore. On the other hand, a rare winter flounder was on its way out to sea after spawning in the bay.

            “The species in Narragansett Bay are a lot like people in Rhode Island,” said Zottoli, a URI graduate student. “Some species are resident, and other species are temperature dependent, so when the water is warm they’re here and they leave when it gets cold again.”
            As Zottoli entered data about the number and size of each species captured, Barber steered the boat toward the mouth of the bay, where they will start the process all over again.
            The original objective of the research project, one of the longest continuing studies of its kind in the world, was to assess the seasonal occurrence of marine life in the bay. No one imagined that the study would still be happening 59 years later. But because it is, the project is providing scientists with a unique window into how the changing climate and other factors have affected the composition of fish in the bay.
            According to URI oceanography professor Jeremy Collie, who has managed the project since 1988, the total biomass of fish and marine invertebrates in the bay hasn’t changed dramatically through the years, but the particular species present has. When the study began in 1959, the dominant species captured were those that preferred cold water, like winter flounder, cunner and hake, and the abundance of fish was evenly spread out throughout the year. But the bay has warmed by about 2 degrees Celsius since then, so warm water species like scup and butterfish have become more abundant, and fish numbers are high in summer and quite low in winter.
            Scup is now the most abundant species captured in the trawl net, with approximately 25,000 individuals caught last year, mostly in the summer and early fall.
            “In the 1990s we thought overfishing was the problem, but since 2000 it’s been clear that climate change has been the big driver of fish communities,” Collie said.
            Other changes have occurred, as well. The community of marine life in the bay has shifted from mostly fish to mostly invertebrates like crabs and squid, probably because invertebrates can consume a wider variety of prey than fish, which often specialize in a small number of prey species. The bay also has fewer species that live on or near the bottom than it used to, because most of the available food is now higher in the water column.
            Over the years, more than 130 different species have been captured in the trawl net and returned to the sea, with a peak of abundance in the 1990s.
            Is there likely to be another shift in fish species coming soon?
            “There is speculation about how the reduction of nutrient inputs from wastewater treatment plants is affecting the overall productivity of the bay.” Collie said. “But there isn’t a clear shift happening yet.”
            He also expects that the composition of marine life in Narragansett Bay will begin to more closely resemble estuaries to the south, like Delaware Bay or Chesapeake Bay. While he has joked that Rhode Islanders may soon have to switch from eating lobster rolls to crab cakes, Collie said “we’re not there yet. We had a couple of really warm years in 2010 and 2012 when we had a lot of blue crabs in the bay, but that peak hasn’t been sustained.”
            The data collected from the study is used by scientists around the world. In addition to URI researchers, it is used by the Rhode Island Department of Environmental Management in its assessments of fish stocks that are important to commercial and recreational fisheries. The data is also incorporated into analyses of fish population trends around the world.
            “It’s important to have a baseline of what things used to be like so you can look at trends over time, like the impact of climate, changes in water quality, and the impact of human activities like power plants,” said Collie.
            The second trawl of the day begins at a spot between Beavertail and Narragansett and covers another mile of seafloor. While sorting, weighing and measuring his catch, Zottoli said it was exciting to see three different kinds of flounder – including one he had difficulty identifying -- plus several skates, blue and rock crabs, and a variety of other species. He called it a hint that spring was finally around the corner.
            Unlike the catch of the first trawl, which is representative of the species found in the middle of Narragansett Bay, the second trawl typically catches species more typical of the open water south of the bay.
            “The water is generally warmer at the first station, so we get more warm-water tolerant fish and a lot more juveniles,” Zottoli said. “Closer to Rhode Island Sound, we get more cold-water species and deep-water species, which is why we got all those little skates.”
            Although the number of individual fish captured was relatively low, Collie said it isn’t surprising or worrisome.
            “I like to think of our fish trawl as monitoring the pulse of Narragansett Bay,” he said. “It’s one indicator of how well the ecosystem is working. We measure its pulse every week and see how the fish population is humming along, like the way you measure your own heart rate. As long as we’re going out there and filling our net over the course of the year and we’re getting healthy specimens, that tells us that we have a healthy bay,” he said.

This article first appeared in the August 2018 issue of Newport Life magazine.

Friday, August 3, 2018

Invasive Asian crab outcompeting young lobsters

            Speculation about the cause of the decline of lobster populations in Narragansett Bay has focused on an increasing number of predatory fish eating young lobsters, warming waters stressing juveniles, and a disease on their shells that is exacerbated by increasing temperatures.
            A new study by a scientist at the University of North Carolina points to another contributing factor – invasive Asian shore crabs.
            The crabs were first observed on the coast of New Jersey in 1988, where they probably arrived in the ballast of cargo ships. They quickly expanded up and down the East Coast – arriving in Rhode Island in 1996 – and they are now found at densities of up to 200 per square meter in the intertidal zones of southern New England.
            “If you flip over a rock, it’s like going into an old basement and turning on a light and
Asian shore crab (RIMEIS)
watching the cockroaches scatter,” said Christopher Baillie, who conducted the study as a doctoral student at Northeastern University. “They’re really abundant.”
            The dramatic increase in the density of Asian shore crabs in the region was followed by a massive decline in the density of green crabs. The green crabs are also not native to the region, having been introduced more than 100 years ago, “but it’s an indication of what the Asian shore crab could be doing to native species,” Baillie said.
            Adult lobsters live in much deeper water than the shallow intertidal zone inhabited by Asian shore crabs, so the two species seldom interact. But some larval lobsters settle in the intertidal and subtidal zones, which they use as nursery habitat. Prior to the arrival of the Asian shore crabs, it was an area that had fewer predators and an abundance of food. But now the young lobsters are finding themselves in competition with the crabs for food and shelter.
            When Baillie surveyed the shoreline in Nahant and Swampscott, Mass., over a five-year period, he found a dramatic increase in the density of Asian shore crabs concurrent with a decrease in the density of juvenile lobsters. He then conducted several laboratory experiments that found that smaller juvenile lobsters lost out to the crabs when competing for food and shelter, especially as the crab numbers increased.
            “We saw that the presence of Asian shore crabs significantly reduced the amount of time the lobsters were able to spend in the shelter,” Baillie said. “The more crabs we introduced, the more times the lobster was displaced. When the crabs were at higher densities, the lobsters spent the entire time fleeing from predation attempts by the crabs.”
            In similar tests, lobsters that were slightly larger than the crabs were able to obtain food and shelter, but the lobsters fed more frequently and ate faster in the presence of the crabs.
            “It appeared that they perceived the crabs as a competitor, and sometimes the lobsters even attacked the crab,” said Baillie. “So while that sized lobster was the dominant competitor, there is a potential energetic cost to battling the crab as well as a potential for injury in those battles.”
            According to Niels-Viggo Hobbs, a lecturer and researcher at the University of Rhode Island who studies Asian shore crabs, Baillie’s research confirms what many scientists have suspected – the crab has a substantial negative impact on young lobsters.
            “There are still a lot of unanswered questions,” he said. “There may also be a positive impact for lobsters. The crabs may provide a food source for adult lobsters. Lobsters love to eat smaller crustaceans, as well as bivalves and other things. The take home message for me is that even when we talk about invasive species, we can’t always say they’re 100 percent bad.”
            Although the crabs arrived in Rhode Island waters at about the same time that lobster numbers began declining in Narragansett Bay, Hobbs said it’s unclear if the crabs were a major factor in the lobster decline.
            “The problem is that on top of Asian shore crabs showing up, we also had lobster shell disease, increasing water temperatures and other factors working to make life for lobsters more difficult. The Asian shore crab certainly didn’t help. It’s difficult to say how bad an impact it had, but it was certainly poor timing if not worse.”
            The long-term implications of Baillie’s study are unclear, since most lobster nursery grounds are in deeper waters than where Asian shore crabs are found.
“But as the crabs continue to expand their range into the northern Gulf of Maine, there is potential for further interactions with juvenile lobsters,” Baillie said. “And while there’s a number of things going on with lobster populations, we’ve shown that the Asian shore crabs may be reducing the value of this nursery habitat for lobsters.”
            Unfortunately, there is little that can be done about the invasive crabs. They are occasionally used as bait by tautog fishermen, but not enough to affect population numbers. And they are too small to be a valuable commercial fishery. A parasite in the crab’s native range in East Asia is believed to castrate the crabs, rendering them unable to reproduce, but releasing the parasite in local waters would likely cause more harm than good.
            “It would be incredibly dangerous to go down that rabbit hole,” said Baillie.
            “The crabs are established and here to stay,” added Hobbs. “So the best we can do is keep an eye on how they impact our native species, and then hope that maybe there’s some good that comes out of it.”
Baillie hopes his study will at least draw attention to the effects the crabs have and prompt government leaders to prioritize what he calls “fairly simple changes in policies” – like requiring the discharge of ballast water in the open ocean – that could be implemented to prevent future introductions of invasive species to the marine environment.

This article first appeared on EcoRI.org on August 1, 2018.