Sunday, April 21, 2019

Giant bony fish being found stranded on New England beaches

            The ocean sunfish earned its moment in the spotlight in 2015 when a viral video surfaced of a foul-mouthed recreational fisherman who observed a specimen along the Massachusetts coastline and excitedly tried to guess what it was as the fish calmly rested at the surface. The largest bony fish in the sea, the pie-shaped creature is certainly an oddity to those who are unfamiliar with it – they bask on their side on the water’s surface and can grow to nearly 11 feet and up to 5,000 pounds by eating almost exclusively jellyfish.
            Like whales, however, they also sometimes become stranded on beaches or in shallow
tidal areas, where they are unable to extricate themselves and die. Almost 350 of them have stranded along the New England coast since 2008, according to Michael Rizzo of the New England Coastal Wildlife Alliance, who studies the species.
            Rizzo presented the results of his analysis of ocean sunfish strandings at the Northeast Natural History Conference in Springfield, Mass., on April 13.
            Also called mola mola – a name derived from the Latin for millstone, a reference to the massive animal’s circular shape – ocean sunfish are found in New England waters each summer and are observed wintering off the coast of the southern U.S.
            “A lot of them wind up stranding in New England every year, starting in August and continuing through early January, but the busiest months are October to December,” Rizzo said. “When they get into shallow areas, they get stuck and can’t get out. Once the tide goes out and they’re in the mud, you can’t move them.”
            A record 81 ocean sunfish were reported stranded in New England in 2017, with an additional 60 stranding in 2018. Staff and volunteers from the alliance attempt to rescue those that are still alive, though few survive. In one case, an ocean sunfish that stranded in a shallow tidal area was towed into open water, only to have it strand again and die a short time later less than a mile away.
            The alliance also collects sighting data of live ocean sunfish to better understand their abundance and activities while in New England.
            Many ocean sunfish are killed or become stranded as a result of fishing gear entanglements and injuries from boat propellers, but the most common cause is cold stunning.
            “That’s a physiological condition an animal can experience due to prolonged exposure to cold water,” Rizzo said. “They become hypothermic and can’t move any more. It’s very similar to what happens to sea turtles.”
            The overwhelming majority of ocean sunfish strandings occur along the coast of Cape Cod Bay, though some have stranded as far north as Portsmouth, N.H. Others have stranded on Nantucket, but none were reported to have stranded along the Rhode Island or Connecticut coast in the last decade.
            “It seems that most of them are going south and get caught up in the fishhook of Cape Cod and they wander around and can’t get out,” Rizzo said. “Once they get around Cape Cod, it seems as if they take a straight shot south and avoid the southern New England coast.”
            Little is known about the population or distribution of ocean sunfish in the area.
            “From what we can tell and from what we have read, the mola population is robust but decreasing, which is why they are listed as vulnerable,” said Carol “Krill” Carson, a marine biologist and president of the alliance. “With many threats to the marine environment, including climate change and marine debris, we are afraid that this species will see continued loss in population numbers.”
Because so little is known about them, the alliance conducts a necropsy (animal autopsy) on as many of the dead ocean sunfish as they can, and samples of numerous tissues are collected for scientists to study. Research is being conducted on their diet and toxicity, as well as on the more than 40 species of parasites that have been found infesting various parts of their body. Efforts are also underway to learn how to determine their age and how best to rescue them from beaches.
            Scientists hope that additional data on ocean sunfish strandings will help to identify why so many are stranding in certain years. Since cold stunning is the primary cause of most strandings, Rizzo and Carson speculate that warming waters due to climate change may be having an effect on the fish by delaying their southbound migration until it’s too late. 
            If that were true, Rizzo said, then the number of sea turtles found stranded should correlate with ocean sunfish strandings, and that isn’t always the case.
            “It was a big year for sea turtle strandings in 2014, for example, but that was a low year for ocean sunfish,” he said. “We’re going to try to do a water temperature analysis to see if that tells us anything.”

This article first appeared on on April 21, 2019.

Friday, April 19, 2019

Spring's arrival brings eggs of all shapes and sizes

             Not long ago I rediscovered in my basement a century-old collection of bird eggs that were passed along to me by a friend who discovered them when cleaning out his own basement about a decade ago. They were apparently collected by a friend of his grandmother.
Contained in a beautiful wooden case and protected by a thick layer of sawdust, the 32 tiny songbird eggs appear to represent many of the species that will be arriving here in Rhode Island on migration in the next few weeks – thrushes, warblers, sparrows, wrens and more – though I’ve been unable to identify most of them. They range from the classic robin’s-egg blue
to pure white, and many have speckles and smears of brown on a white, tan or gray background. They’re almost too delicate to handle.
            Because it’s the season of the Easter bunny and his delivery of eggs to good boys and girls – or maybe that’s Santa Claus – it got me thinking about the wide variety of wildlife eggs that are certain to be laid and hatched during this season of renewal.
            Birds lay round, oblong or oval eggs of varying sizes and colors, depending on the species. Many bluebirds and phoebes are already sitting on their eggs by now.  Tiny chicks of great horned owls and barred owls have already hatched and are growing in their nests under parental care. But most of the birds that breed in our area have yet to get started.
            That’s not true of most of the egg-laying amphibians in southern New England. Several weeks ago, most wood frogs, spring peepers and spotted salamanders laid their eggs wrapped in a bad-tasting jelly-like coating that protects them from be being eaten by predators before they hatch in local ponds. Green frogs and American toads are due to do the same thing any time now. When the eggs hatch a couple weeks later, the emerging tadpoles spend several months growing into adults before climbing out of the water and spending most of the rest of their lives on land.
            Snakes are an unusual case. About two-thirds of the world’s snakes lay eggs, but the rest give birth to live young. Among the egg-layers in our area are ring-necked snakes, milk snakes and black racers, while two of our most common snakes, the garter snake and northern water snake, bear live young. For most species, egg-laying takes place in June or July, and they hatch a month or two later. But don’t expect to stumble across snake eggs like you might find bird eggs or frog eggs. They’re typically laid in a burrow or under soft soil in inconspicuous places.
            That’s not necessarily true of turtle eggs, however. Most dig nests in the sandy soil adjacent to the ponds where they spend most of their lives, and the disturbed soil is often a give-away to the location of the nest. Raccoons know that, so they dig amid the disturbed soil to find and eat whatever eggs they can unearth. The large size of snapping turtle nests make them especially vulnerable to raccoons, and I know several places where snappers nest every year and where I usually find the remains of their shells after having been predated.
            But somehow, despite all the threats that nature – and humans – put in their way, enough of those eggs tend to survive to hatching, and enough of the hatchlings make it to adulthood to keep the species going. Even those that aren’t known to breed like Easter rabbits.

This article first appeared in The Independent on April 18, 2019.

Friday, April 5, 2019

Sea potato invasion hits Rhode Island shore

            During a class field trip to Mackerel Cove in Jamestown in 2017, University of Rhode Island student Jacob Reilly picked up an unusual brown seaweed that looked like a hollow ball and asked his professor what it was. The answer was a surprise.
Reilly had stumbled upon the first appearance in Rhode Island of what has come to be called sea potatoes (Colpomenia peregrina), an invasive seaweed native to the coast of Korea and Japan that grows on top of other seaweeds.
“It’s not a parasite; it just settles and grows on top of other algae,” said Lindsay Green-Gavrielidis, a marine ecologist and URI postdoctoral researcher who teaches the class. “We don’t know what impact it’s having on native seaweeds, though we hypothesize that it may be in
direct competition for nutrients and light. But nobody has done any research to quantify its impact.”
Green-Gavrielidis has a history with the invader. Sea potatoes had been unintentionally introduced to Europe sometime in the early 1900s, probably in ship ballast, and from there it made its way to Nova Scotia in the 1960s. It took until 2010 for it to be discovered in the Gulf of Maine, when Green-Gavrielidis found it while conducting research for her doctorate at the University of New Hampshire.
In addition to the ball-shaped form it typically takes, the seaweed also forms a crust that grows on rocks that easily goes unnoticed, so Green-Gavrielidis speculated that it may have been “hiding out for a long time like that, and then when the conditions were right the ball form started appearing.”
The appearance of sea potatoes along the Rhode Island coast is significant because it has crossed what Green-Gavrielidis calls a major biogeography boundary – Cape Cod. The waters to the north of Cape Cod are dominated by the Labrador Current from Greenland, which makes for colder, more nutrient-rich waters. South of the Cape is dominated by the warm Gulf Stream.
“What it says about sea potatoes is that it has a really broad tolerance for a variety of conditions, and not many species can do that,” she said. “Most species don’t have the ability to move to such very different places. Species that are successful invaders do. We were hoping it wouldn’t be able to cross into this geographic region because of the different conditions.”
            To determine how common sea potatoes are in Rhode Island waters, Green-Gavrielidis conducted a methodical search for it at 13 sites along the state’s coastline last year and conducted several quantitative surveys to compare its abundance to a similar native species called sea cauliflower.
In addition to Mackerel Cove, sea potatoes were also found at East Beach and Ninigret Pond in Charlestown and South Ferry Beach in Narragansett. It was not found any further north in Narragansett Bay than South Ferry Beach, perhaps because the native seaweed it is most commonly associated with, rockweed, is not found in abundance in the upper bay. No sea potatoes were found in Westerly or eastern Connecticut, either, so it has not likely found its way into Long Island Sound yet.
            “The biomass we found in Rhode Island is much lower than what we found in the Gulf of Maine, so maybe it hasn’t been here as long,” said Green-Gavrielidis. “That might also be because the environmental conditions are such that it’s not doing so well here.  We do have some preliminary data that shows that there are herbivores – snails primarily – that eat it, so that’s good.
            “Often you think that when a new species comes on the block, there isn’t something that consumes it,” she added. “But we’ve done studies that show that the common periwinkle will readily and happily pursue it.”
            That’s a good sign, since there is little that can be done to stop it.
            “We need to continue monitoring it to see if its going to increase in abundance,” she said. “We expect it to continue spreading. Whether it moves up into the bay or west to Long Island Sound is unknown. And whether it’s a good thing, a bad thing or neither, only continued research can tell us.”
            Green-Gavrielidis and URI colleague Niels-Viggo Hobbs will be conducting a new research project this summer and fall that involves sampling rockweed habitats – the native seaweed most closely associated with the sea potato invasion – so they will be keeping an eye out for the newly arrived seaweed. Their students are also conducting laboratory studies to determine whether native seaweed-eating marine life will eat it and if it is preferred over native seaweeds.

This article first appeared on on April 4, 2019.