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Microbes
may have
killed fish
Karlodiniumis detectedby lab tests
By MIKE VOSS
Contributing Editor
Toxin released by a dinoflagellate called karlodinium may have been a contributing factor in an Aug. 6 fish kill that left more than 3.9 million fish dead in a section of the Pamlico River.
Preliminary laboratory results from the N.C. Division of Water Quality indicated that an unusually high number of karlodinium was present in the water where the fish kill occurred. Karlodinium, a plant-like dinoflagellate, releases a toxin — karlotoxin — that damages the gills of fish and can basically cause them to suffocate, according to a news release from the Pamlico-Tar River Foundation.
Karlodinium is found more often in the Chesapeake Bay than in North Carolina waters, said Heather Jacobs, the riverkeeper for the Pamlico-Tar River, on Tuesday. In North Carolina waters, the last known fish kill caused by karlodinium occurred in the Neuse River in 2006, according to PTRF.
“It’s not unusual to see it here,” Jill Paxson, supervisor of the Pamlico River Rapid Response Team, said Tuesday. “We’ve seen it a few times this summer.”
The team has investigated several fish kills this summer, including three in less than a week.
Most dinoflagellates are marine plankton, but they can be found in fresh-water habitats, too.
Also present in the water at the time of the fish kill was a bloom of blue-green algae also known to be toxic at times, according to the preliminary lab results.
“Since the kill consisted of mainly juvenile menhaden, which are filter feeders, the death is more likely associated with the toxin. Low oxygen levels would have produced a kill with multiple species of fish, not just menhaden,” according to the PTRF release. “Conditions appeared to have been ideal for the karlodinium organisms to bloom and out compete other species of algae. Karlodinium was also associated with a subsequent fish kill of close to 1,000 menhaden on August 15 along the Washington Park waterfront.”
Karlodinium and similar organisms thrive in nutrient over-enriched waters.
“They bloom because there’s high nutrient availability,” Paxson said.
Nitrogen and phosphorus are among nutrients that karlodinium and similar microbes feed on, according to Paxson and PTRF.
PTRF’s news release indicates it believes that nutrient overloading in the state’s waters is just part of a larger problem in regard to water quality.
“Over enrichment of a waterbody by nutrients, also called eutrophication, leads to hypoxic conditions (i.e. little to no oxygen). The latest fish kills are a symptom of a much larger problem,” reads the release.
Karlodinium is more plant-like than pfiesteria piscicida, which is more animal-like, Jacobs said.
In some previous years, fish kills, which included fish with lesions, in the Pamlico and Neuse rivers, were caused by pfiesteria piscicida, a small organism, according to JoAnn Burkholder and other researchers at N.C. State University. They said pfiesteria piscicida could cause lesions on fish. Other factors such as parasites, bacteria and viruses can cause lesions or sores on fish, according to scientists.
In 2004, the National Oceanic and Atmospheric Administration awarded $53,905 to the N.C. State University Center for Applied Aquatic Ecology to examine the reproductive cycles of a toxic dinoflagellate, specifically karlodinium. Researchers plan to use the research to reduce economically disastrous fish kills.
“Specifically, North Carolina researchers will examine patterns of asexual and sexual reproduction in the organism that has been associated with economically damaging fish kills in estuaries along the entire U.S. Atlantic coast,” reads a news release from NOAA.
“Fish kills and harmful algal blooms cause serious economic and public health problems everywhere. The better we understand how blooms form, the better we can predict, prevent and minimize the effects,” said Conrad C. Lautenbacher, undersecretary of commerce for oceans and atmosphere and NOAA administrator, about the award.
Paxson said her team, when possible, will collect water samples containing karlodinium so researchers can continue to study the microbe. The more research conducted on karlodinium, the better the chance to understand how it affects the environment, she said.
killed fish
Karlodiniumis detectedby lab tests
By MIKE VOSS
Contributing Editor
Toxin released by a dinoflagellate called karlodinium may have been a contributing factor in an Aug. 6 fish kill that left more than 3.9 million fish dead in a section of the Pamlico River.
Preliminary laboratory results from the N.C. Division of Water Quality indicated that an unusually high number of karlodinium was present in the water where the fish kill occurred. Karlodinium, a plant-like dinoflagellate, releases a toxin — karlotoxin — that damages the gills of fish and can basically cause them to suffocate, according to a news release from the Pamlico-Tar River Foundation.
Karlodinium is found more often in the Chesapeake Bay than in North Carolina waters, said Heather Jacobs, the riverkeeper for the Pamlico-Tar River, on Tuesday. In North Carolina waters, the last known fish kill caused by karlodinium occurred in the Neuse River in 2006, according to PTRF.
“It’s not unusual to see it here,” Jill Paxson, supervisor of the Pamlico River Rapid Response Team, said Tuesday. “We’ve seen it a few times this summer.”
The team has investigated several fish kills this summer, including three in less than a week.
Most dinoflagellates are marine plankton, but they can be found in fresh-water habitats, too.
Also present in the water at the time of the fish kill was a bloom of blue-green algae also known to be toxic at times, according to the preliminary lab results.
“Since the kill consisted of mainly juvenile menhaden, which are filter feeders, the death is more likely associated with the toxin. Low oxygen levels would have produced a kill with multiple species of fish, not just menhaden,” according to the PTRF release. “Conditions appeared to have been ideal for the karlodinium organisms to bloom and out compete other species of algae. Karlodinium was also associated with a subsequent fish kill of close to 1,000 menhaden on August 15 along the Washington Park waterfront.”
Karlodinium and similar organisms thrive in nutrient over-enriched waters.
“They bloom because there’s high nutrient availability,” Paxson said.
Nitrogen and phosphorus are among nutrients that karlodinium and similar microbes feed on, according to Paxson and PTRF.
PTRF’s news release indicates it believes that nutrient overloading in the state’s waters is just part of a larger problem in regard to water quality.
“Over enrichment of a waterbody by nutrients, also called eutrophication, leads to hypoxic conditions (i.e. little to no oxygen). The latest fish kills are a symptom of a much larger problem,” reads the release.
Karlodinium is more plant-like than pfiesteria piscicida, which is more animal-like, Jacobs said.
In some previous years, fish kills, which included fish with lesions, in the Pamlico and Neuse rivers, were caused by pfiesteria piscicida, a small organism, according to JoAnn Burkholder and other researchers at N.C. State University. They said pfiesteria piscicida could cause lesions on fish. Other factors such as parasites, bacteria and viruses can cause lesions or sores on fish, according to scientists.
In 2004, the National Oceanic and Atmospheric Administration awarded $53,905 to the N.C. State University Center for Applied Aquatic Ecology to examine the reproductive cycles of a toxic dinoflagellate, specifically karlodinium. Researchers plan to use the research to reduce economically disastrous fish kills.
“Specifically, North Carolina researchers will examine patterns of asexual and sexual reproduction in the organism that has been associated with economically damaging fish kills in estuaries along the entire U.S. Atlantic coast,” reads a news release from NOAA.
“Fish kills and harmful algal blooms cause serious economic and public health problems everywhere. The better we understand how blooms form, the better we can predict, prevent and minimize the effects,” said Conrad C. Lautenbacher, undersecretary of commerce for oceans and atmosphere and NOAA administrator, about the award.
Paxson said her team, when possible, will collect water samples containing karlodinium so researchers can continue to study the microbe. The more research conducted on karlodinium, the better the chance to understand how it affects the environment, she said.
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