Fish die-off in Delaware – 09/14/2005

  • November 12, 2013 at 12:17 am #990

    Millions of fish found dead in Sussex
    Three menhaden kills in a day a first in state; algae examined

    BY MOLLY MURRAY / The News Journal
    09/10/2005Barbara Minuti heard the plop, plop, plop of menhaden
    breaching the surface of Torquay Canal as they gasped for air in the

    “It sounds like Alka-Seltzer,” said Joseph F. Minuti, her
    husband. “That’s usually a telltale sign.”

    By Thursday morning, a million juvenile menhaden were floating belly-
    up in the canal, like silver leaves on the tea-brown water.

    A few miles away, at Arnell Creek, the same thing was happening.
    About 100,000 1- or 2-inch-long menhaden were found dead there.

    Farther south in Rehoboth Bay, near Masseys Landing, another fish
    kill was under way, with 1 million more fish dead there.

    All told, an estimated 2.1 million menhaden died over the course of a
    few hours Thursday in tributaries of Rehoboth Bay.

    State environmental officials believe low oxygen in the water was the
    cause, said Craig Shirey, state fish kill coordinator. Water samples
    are being tested, and it is possible that a toxic algae could have
    contributed to the kills.

    A major fish kill was not unexpected this summer because fisheries
    scientists found record numbers of young menhaden in the Inland Bays
    in samples collected earlier this year. But there had been no major
    kill until Thursday.

    When it did come, it broke many of the rules scientists thought they
    had pulled together to explain what has been killing the fish in the
    Inland Bays for more than a decade.

    The three kills were extraordinary because never in the 25 years that
    state environmental officials have monitored fish kills have there
    been three on one day — two of them massive, said Robin Tyler, a
    senior scientist with the state Department of Natural Resources and
    Environmental Control.

    Tyler said officials thought they had a pretty good understanding of
    what was causing fish kills in the bays. But Thursday’s kill will
    force some rethinking.

    Normally, fish kills occur when the water is warm, the days and
    evening are hot and humid, and the air is still — the type of
    weather Delaware had for most of summer

    Normally, the large fish kills occur in July and August. Only eight
    of the 51 fish kills DNREC has recorded in 25 years have come in
    September, Tyler said.

    But the typical scenario “may be not the only one,” because
    conditions were not typical this week.

    “We have had beautiful weather for a week now,” Tyler said.

    This series of kills “broke a lot of the rules,” said Ed Whereat, who
    runs the University of Delaware’s Citizen Monitoring Program and does
    water-quality sampling for the state.

    Things started happening early Thursday morning, when residents at
    Mariners Cove, off Long Neck Road, reported fish were dying in a
    lagoon there.

    Whereat found thousands of dead fish in the dead-end lagoon off Lee
    Joseph Creek, he said.

    By the time water samples were taken, oxygen levels in the water had
    begun to rise because the sun had been up for a while and warmed the
    water, he said.

    Levels of dissolved oxygen in the canal, which fish such as menhaden
    depend on to survive, were low, but probably not low enough to have
    caused the fish kill.

    “It was not lethally low at that point,” he said.

    Whereat’s water samples also showed high densities of a sometimes
    toxic algae: Chattonella cf. verruculosa. Whereat said he sent the
    samples to another test lab to see if the levels were toxic.

    The algae density in the canal was within the range that can produce
    toxins, Whereat said, but samples with higher concentrations of the
    algae previously found in the Inland Bays have not produced toxins.

    “It seems like it’s pretty infrequently toxic,” Whereat said.

    Test results should be available in about a week, he said.

    Tyler was out doing his regular weekly sampling when he stumbled upon
    the kill at Torquay Canal, another man-made lagoon prone to stagnant

    A woman who lives in the neighborhood reported that at about 6:30
    a.m., the fish were clustered around a device that is designed to
    increase oxygen in the water column, he said.

    “That must have been where the last little bit of oxygen was,” Tyler

    Tyler said he has a theory about what may have caused the late-season

    Some algae thrive in the warmer waters of summer, and others come
    into their own as the water cools and summer ebbs to fall.

    It could have been “the crash of one bloom and the development of
    another,” Tyler said.

    Algae play a significant role in water quality in the Inland Bays
    because too much of it can quickly deplete oxygen in the water.
    Algae, like other plants, produce oxygen through photosynthesis. But
    when it is dark, or on cloudy days, their oxygen production drops.

    Like other plants, algae grow faster when fertilized.

    The Inland Bays contain an excess of nitrogen and phosphorus from
    sewer plants, septic systems, runoff from farms and developments.
    Nitrogen also reaches the bays from the atmosphere.

    Joseph Minuti said the kill really didn’t come as a surprise.

    “You know this is going to happen once a year,” he said.

    Contact Molly Murray at 856-7372

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