Sunday, July 23, 2017

Is it lights out for the firefly?

            Remember the summers when so many insects would splatter on your car’s windshield that you had to scrub them off to get a decent view through the glass? You probably haven’t had to do that nearly as often as you used to. And while you may be happy to avoid that chore, it is an unfortunate sign that insect numbers have declined dramatically in recent decades.
            Researchers have found that the total mass of insects in some areas has declined by as much as 80 percent since the 1980s, and that has dramatic implications for wildlife, especially for bats and insect-eating birds like flycatchers, swifts and swallows.
            One of those insects that is noticeably absent from many fields and forests these days is the popular firefly. I remember fondly the summer days of running through my neighborhood
Cartoon by David Chatowsky in Newport Daily News
fields and forests just after dusk trying to catch lightning bugs in a glass jar, then watching the captured insects blink on and off until bedtime. It’s an experience that few of today’s children have had, since fireflies are harder and harder to find in any numbers.
            An excellent new book called Silent Sparks by a Tufts University professor sheds light on the natural fireworks display put on by native fireflies. Sara Lewis calls the flickering lights a “spectacular bioluminescent courtship display” in which males emit a specific pattern of illuminated pulses. The males of the most common firefly species in New England, Photinus greeni, produce a distinctive pair of pulses separated by 1.2 seconds, followed by a four second pause before repeating the pulses. If he’s lucky, an interested female will reply with a single prolonged flash that rises in brightness before fading.
            “Each time he shines his light, the male pauses for an instant in hopes of spotting a female,” she wrote. “So tonight it’s wink, wink, hover and hope…wink, wink, hover and hope.”
            Sadly, that hope is more and more turning to hopelessness. Even in locations where firefly numbers are relatively high, males often struggle to find a mate, since females are often outnumbered by males 20 to 1. In many areas, males may flash for days without getting a response.
            Repeated flashing by fireflies can be costly, as the illumination not only signals their location to receptive female fireflies but also to predators seeking to eat them.
            The reasons for the disappearance of fireflies – and so many other once-common insects – is unclear. Habitat disturbance is an obvious one. Most firefly species are found around fields and forests and marshes, which in many areas have given way to pavement and houses and shopping centers. Pesticides and other pollutants are likely contributing factors as well.
            Surprisingly, light pollution has also been implicated in the decline of fireflies. Since the insects use their flashing lights to communicate, the abundance of man-made lighting from streetlights, stores and cars is believed to make it difficult for the insects to signal each other. And those species that synchronize their flashes during courtship get out of sync when a car’s headlights pass by.
            So the next time you see the flashing of a firefly in the evening, celebrate the memories these cherished insects provide, and mourn the fact that few in the younger generation will be able to share those memories.

This article first appeared in The Independent on July 20, 2017.

Tuesday, July 18, 2017

Eelgrass declining in Rhode Island waters

           Michael Bradley calls eelgrass “the canary in the coal mine for estuarine health.” The flowering plant that grows beneath the surface of coastal waters and salt ponds provides nursery habitat for shellfish and finfish while also dampening wave energy, stabilizing sediments and serving as an indicator of clean water.
            But according to a recently issued report by the University of Rhode Island’s Environmental Data Center, eelgrass in Rhode Island is declining in Narragansett Bay and in
Eelgrass photo  courtesy of NOAA
most of the state’s coastal salt ponds.
            The report found 1,144 acres of eelgrass and other submerged vegetation in state waters, an 18 percent decrease from 2012. The largest declines occurred in Quonochontaug Pond (52 percent), Point Judith Pond (48 percent) and Little Narragansett Bay (25 percent).
            More than half of the state’s eelgrass occurs around Jamestown, which experienced a 19 percent decrease in eelgrass acreage. Ninigret Pond was the only coastal pond not to have a decrease, and the Narrow River was the only site that experienced a significant increase (45 percent) since 2012. 
            “It’s difficult to know exactly what’s going on,” said Bradley, a URI research associate and lead author of the report. “The reasons can be varied. An increase in water temperature could have something to do with it. Pollution in the water or soil could have something to do with it. And severe storms like Hurricane Sandy could certainly affect it. We need more surveys, more data and more analyses to get a better handle on what is determining eelgrass changes.”
            Eelgrass beds can also be degraded by algal blooms or disease or be physically damaged by human activities like shallow-water boating, dredging, and construction of docks and other structures.
            Data for the report was collected by aerial surveys funded by the Rhode Island Coastal Resources Management Council.
            Bradley said that the decline in eelgrass is worrisome. “If you care about shellfish, if you like to have scallops, if you care about commercial or recreational fishing, then you should care about eelgrass,” he said. “The bottom line is that’s where the little critters go to hide to become big critters that can become commercially or recreationally available.”
            Anecdotal reports suggest that eelgrass was abundant throughout Narragansett Bay a century ago, but most of it was wiped out during the 1930s and 1940s due to a naturally-occurring disease. When the first aerial surveys of eelgrass were conducted in 1996 by Save the Bay and the Narragansett Bay Estuary Program, they found just 100 acres of eelgrass in the bay.
            “Those results spawned a big restoration effort,” Bradley said.
            When Bradley conducted his first aerial surveys of eelgrass in Narragansett Bay in 2006, he found that eelgrass acreage had tripled to about 300 acres.
            “What we learned, though, was that technology has come a long way,” he said. “The survey methods were very different from 1996, based on new technology, so we have to be very careful when we compare the results.”
            The results of a 2012 survey showed a further increase in eelgrass acreage before declining in 2016.
            This year, Bradley intends to conduct an accuracy assessment of the 2016 mapping using underwater video cameras and global positioning systems to determine how much error is associated with the aerial survey method. He will also test the use of drones for conducting future surveys.
            What can be done to ensure that eelgrass doesn’t continue to decline in the state? That’s another question without an easy answer.
            “Anything we can do to help clean the bay would be useful. But there are not enough pictures and not enough numbers to base confident policy and management decisions on yet,” Bradley said. 

Saturday, July 8, 2017

Recent right whale deaths have scientists worried

            The deaths of six North Atlantic right whales in the Gulf of St. Lawrence last month have raised alarms among whale biologists who fear for the future of one of the rarest whales on Earth.
            Robert Kenney, a marine mammal expert at the University of Rhode Island’s Graduate School of Oceanography, called the unexpected deaths “a major concern” because the population of right whales totals fewer than 500 animals and their numbers have been declining since 2011. The dead whales represent more than 1 percent of the population.
            While the deaths raise many questions, one of the first, according to Kenney, is what were they doing in the Gulf of St. Lawrence in the first place?
            “Right whales go to the same places to feed every year – the Great South Channel, the Bay of Fundy, the Nova Scotia shelf – feeding grounds they probably learned from their mothers in
North Atlantic right whale mother and calf (Center for Coastal Studies)
their first year of life,” said Kenney, who manages the sighting database for the North Atlantic Right Whale Consortium. “But recently they seem to be wandering farther afield. If there’s not enough food where they traditionally feed, they go to other places. That’s what we think is going on.”
            What caused the deaths of the six whales in the Gulf of St. Lawrence – the water body surrounded by Newfoundland, Quebec, Nova Scotia and New Brunswick – is uncertain. Preliminary results of necropsies on three of the animals showed evidence of blunt trauma from ship strikes on two of the whales and fishing gear entanglement on the third. But a news release from Canada’s Marine Animal Response Society said that other problems that "may have predisposed these animals to this trauma cannot be ruled out at this stage."
            Kenney is suspicious that a toxic algae bloom or some sort of disease may have been a factor. In 1987, a dozen humpback whales died from eating mackerel laced with a red tide toxin, he said.
            Right whales were nearly driven to extinction due to commercial whaling. They were slow to recover, though their population increased steadily at about 3 percent per year from the 1980s through 2010, with what Kenney called “a little blip” in the late 1990s.
            “That little blip is exactly the same thing that’s happening right now,” he said. “Survival rate didn’t change; that’s been relatively constant all the way through. What changes is the number of calves being born. At the end of the 90s the number of calves born dropped off for three years. Since 2010, the number of calves has been lower than the number needed to replace the average mortalities in six of eight years, and just barely positive in the other two.”
            Just five right whale calves were born this year, so the death of six whales last month ensures that the population will decline again, regardless of whether any other animals die during the rest of the year. Prior to the six deaths in the Gulf of St. Lawrence, one right whale died from a ship strike in April off Cape Cod, where the animals feed in late winter and early spring.
            “The decline in the birth rate is more concerning now because climate change might have a hand in the changes taking place in the food supply,” Kenney said.
            According to Kenney, the copepod the right whale’s eat, Calanus finmarchicus, may no longer be found in dense and long-lasting patches in the places the whales usually find them, due largely to warming ocean temperatures and the changing currents and circulation patterns.
            Kenney said that one reason he is worried about the health of the right whale population is that “too many are still being killed that don’t have to be.”
            In recent decades, most right whales have died from human causes -- ship strikes or fishing gear entanglement. The ship strike issue has improved, thanks to regulations requiring ships to slow to 10 knots when traveling through areas where whales are known to reside at certain times of year. But the fishing gear entanglement issue seems to be getting worse.
            “The National Marine Fisheries Service has been nibbling at the edges of this issue for a long time because they aren’t willing to impose severe measures on the fishery,” Kenney said. “The agency responsible for promoting the fishery is the same agency responsible for regulating marine protected species. That was a dumb idea when it happened during the Nixon administration and it’s still a dumb idea today.”
            The conservation community has proposed that fishermen be required to use ropes with a breaking strength of 1,700 pounds on their buoy lines in nearshore waters, and that the government support expanded testing of gear without any buoy lines. Research by NewEngland Aquarium and others on rope strength and the muscle power of whales has shown that most whales would be able to disentangle themselves by breaking 1,700-pound ropes. But the fishermen are using stronger and stronger ropes. Some ropes removed from entangled whales had breaking strengths up to 12,000 pounds.
            While Kenney is concerned about the right whale population, he is less concerned about the humpback whale population, despite the 47 humpbacks that have been found dead along the East Coast since 2016, including one that washed ashore on Jamestown and two on Cape Cod last month.
            North Atlantic humpbacks were removed from the federal endangered species list last fall, and Kenney said that as the population increases, higher levels of natural and human-caused mortality are expected.
            “Given the large number of live humpbacks along the mid-Atlantic this winter, I suspect that there are more than the usual number of juveniles chasing food relatively close to shore – like the one that was seen repeatedly just off the Narragansett Pier seawall – and putting themselves in harm’s way,” he said. “Ship strike and entanglement mortality for all species is highest in juveniles.”

This article first appeared on on July 7, 2017.