More Jellyfish, Phytoplankton, Warmer Water This Season

     Monday and Tuesday are standard entries in a day planner, but unless you are Megan Zottoli of Woods Hole, Jellyfish Day is not.
     As a swimming instructor at Stony Beach, Ms. Zottoli can count on two Jellyfish Days a summer over a six-week period, but this year has been different. “I would say we have had at least one a week,” she said. “We have had about seven days where we have had bad jellyfish.”
     Her term for that is Jellyfish Day—when instruction is impacted by a large influx of the free-floating creatures, at least every six feet, into Stony Beach waters. One day this summer, she encountered more than 300 of them.
     “There were more this summer than in the past,” she said. “They come in with the wind and also with the warmer water.”
     Conditions have also been ripe this summer for another creature of the sea, albeit less harmless than the stinging jellyfish, that has caused alarm in Cape waters: phytoplankton.
     At the Division of Marine Fisheries office, senior biologist David Whittaker said he has received numerous calls from concerned residents noticing the red discoloration of the water caused by the blooms—some as large as a half-mile—of these species.
     In addition to Falmouth, he said, the blooms have been reported in Wareham, Bourne, Onset, and in bays near Barnstable.
     Unlike red tide, which is toxic, Mr. Whittaker said phytoplankton blooms do not pose a threat to humans or fish. “With this organism you will see the water turning red, almost like a ketchup color in the water. It gives more of a red color in the water than toxic red tide,” he said. “It is not toxic to people or animals, except it is a little disconcerting to see the water turning red.”
     A 29-year veteran of the state agency, he said there was a time when the blooms sporadically appeared every few years. That changed over the past five years, he said, when they have been as common as the rising and setting sun.
     Although hesitant to correlate them to global warming, he said his department has noticed a slight increase in water temperatures during the same time. “I can’t say it is a remarkable increase, but there has been a general increase,” he said. “It is probably one of the factors that helps them survive and thrive from one year to the next.”
     Conditions over the past week in Falmouth, he said, during which there was a period of heavy rains followed by sunshine, allow phytoplankton to thrive. “It is photosynthesizing phytoplankton,” he said. “Fresh water and sunlight are what it needs to reproduce and grow. If those conditions are maintained, they will continue to grow.”
     Unlike past years, he said, the blooms are showing up three weeks early.
     Their arrival has coincided with the warmest water and air temperatures seen in Falmouth over the past five years.
     Meteorologist Richard S. (Doc) Taylor of Menauhant said that July was the warmest on record since 2003, with an average temperature of 75.5 degrees. The next warmest during that time period, he said, was 2006 in which temperatures averaged 74.7 degrees.
     “We didn’t have many 90 degree days in July, but we had a lot of high minimum temperatures which helps,” he said. “And we had a lot of days in the 80s.”
     Similarly, he said, the average temperature in June, 68.6 degrees, was the highest it has been over the past five years.
     To correlate temperatures with an explosion of jellyfish is difficult, said Kelli C. Rakow, a graduate student at the Woods Hole Oceanographic Institution.
     Simply through observation, she said, “it does seem like there are more jellyfish than usual this summer.”
     From year to year, she said, there is a natural variability in the numbers of jelllyfish found in local waters. This is related to not only water temperatures, but also currents, winds, food source, as well as number of predators.
     While her interest is in salps, oceanic jellies found far from shore, she said those found in Falmouth’s waters this summer tend to be smaller and fall into three categories.
     They include lion’s mane jellyfish, the only one that stings, and two species of comb jellies: mnemiopsis, or sea walnut; and beroe, a specialist that feeds on mnemiopsis. The comb jellies, she said, are harmless from a human standpoint. “They just get in our way when we are trying to swim,” she said. “They mostly eat small phytoplankton in the water column.”
     Lion’s mane is also carnivorous, eating tiny animals, including comb jellies.
     In years past, she said, the Cape has also been a habitat for moon jellies, another stinger, but she has not seen as many of these this summer.
     Where jellyfish go, Ms. Rakow said, leatherback turtles are sure to follow. She is currently assisting a local scientist who is studying leatherback turtles and their feeding behavior on jellyfish. “A lot of leatherbacks will come close to shore because there are so many jellies,” she said. “The unfortunate thing is there are a lot more ship strikes because they are coming to shore to feed.”
     The most direct threat the jellyfish pose to humans is, of course, their sting. Sheila T. Regan, a staff guard with Falmouth Beach Department, said there are a number of remedies her colleagues take when it comes to treating a sting.
     “The best thing to do is take wet sand and use it as an exfoliator on the skin. It gets off the stinging and basically kills the pain,” she said. If that does not work, she said, lifeguards also will employ vinegar, which also helps alleviate pain.
     In her seven years with the beach department, Ms. Regan said, this summer has not been noticeably worse. Compared to the Portuguese man-of-war, which wreaked havoc in Falmouth two years ago, she said, jellyfish have not had nearly the same impact on swimmers this year. “Jellyfish hurt, but it is nothing like the man-of-war,” she said.
     The currents and the wind, she said, often determine where jellyfish will show up. In recent weeks, she said, both Menauhant and Bristol Beach have been their primary destination.
     While the numbers of jellyfish are increasing worldwide, Ms. Rakow said, it is difficult to correlate that to one specific factor. It can range from everything to water temperatures increasing, she said, to a decline in water quality, as jellyfish do well in high-nutrient, low-oxygen waters, unlike many other fish.
     “There are general trends that hold,” she said. “Jelly blooms in different parts of the world are specific to the environmental conditions in those areas.”