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T.D. Bills

Publications and source records attributed to T.D. Bills.

At least 19 recordsLinked to original sources

Relation of concentration and exposure time to the efficacy of niclosamide against larval sea lampreys ( Petromyzon marinus )

The efficacy of 2’, 5-dichloro-4’-nitrosalicylanilide (niclosamide) at various concentrations and exposure times was tested against free-swimming larval sea lampreys ( Petromyzon marinus ) at 12°C and 17°C in Lake Huron water. Concentrations of niclosamide in test solutions ranged from 0.46 to 4.7 mg/L with pH 7.8 to 8.3, total alkalinity 78 to 88 mg/L as CaCO 3 , and total hardness 95 to 105 mg/L as CaCO 3 . In each test, six groups of larvae were exposed to a single concentration of niclosamide for times ranging from 30 s to 30 min. Exposure time was treated as the dose and, for each concentration tested, the exposure time necessary to kill 50 and 99.9% of larvae (ET50 and ET99.9) was determined. Linear regressions of the log 10 -transformed ET50 and ET99.9 on the log 10 -transformed niclosamide concentrations were significant at both temperatures with r 2 ranging from 0.94 to 0.98. The predicted ET50 ranged from 58 sec to 21.7 min and the ET99.9 ranged from 2.5 to 43.5 min across the concentrations and temperatures tested. Niclosamide required a significantly longer time to kill larvae at 12°C than at 17°C.

Journal of Great Lakes Research

Acute toxicity of TFM and a TFM/niclosamide mixture to selected species of fish, including lake sturgeon ( Acipenser fulvescens ) and mudpuppies ( Necturus maculosus ), in laboratory and field exposures

The toxicity of the lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2',5-dichloro-4'-nitrosalicylanilide (niclosamide) to non-target fishes has been a major point of concern since their use to control larval sea lamprey ( Petromyzon marinus ) populations began in the early 1960s. The toxicity of TFM to several non-target fish species has been demonstrated in previous studies. However, little information is available on the toxicity of the TFM/1% niclosamide mixture. One species of particular concern is the lake sturgeon ( Acipenser fulvescens ). Juvenile lake sturgeon of several size ranges were exposed to determine potential effects of the lampricides to individuals present in treatment streams. Sac fry were most resistant to the lampricides followed by fingerlings in the 200 to 225 mm size range. Swim-up fry and fingerlings less than 100 mm were the most sensitive. Concentrations that produced 50% mortality (LC50s) in juvenile lake sturgeon of these smaller size ranges were at or near the minimum lethal concentrations (MLCs) required for effective control of larval sea lampreys. The mudpuppy ( Necturus maculosus ), an amphibian native to several tributaries of the Great Lakes, have also become a species of interest in recent years. Laboratory tests conducted with TFM and a TFM/1% niclosamide mixture on adult mudpuppies indicate that although the amphibian is sensitive to the lampricides, an adequate margin of safety exists for adult mudpuppies to survive when exposed during stream treatments. Fifteen other fish species native to streams treated with lampricides were investigated in the laboratory to determine their sensitivity to the lampricides. Centrarchids, bluegill ( Lepomis macrochirus ) and green sunfish ( Lepomis cyanellus ) were the least sensitive to TFM, while ictalurids, black bullhead ( Ictalurus melas ), channel catfish ( Ictalurus punctatus ), and tadpole madtom ( Notorus gyrinus ) were the most sensitive. On-site bioassays conducted before lampricide treatments also revealed that lake sturgeon, channel catfish, and whitefish ( Coregonus clupeaformis ) were sensitive to the lampricides although considerably less sensitive compared to sea lamprey.

Journal of Great Lakes Research

Effects of lampricide exposure on the survival, growth, and behavior of the unionid mussels Elliptio complanata and Pyganadon cataracta

The effects of a 12-h exposure to the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) and a combination of TFM and 1% niclosamide (active ingredient in Bayluscide 70% wettable powder) on the short and long-term (10 mo post exposure) survival and behavior of two unionid freshwater mussel species Elliptio complanata and Pyganadon cataracta were measured. Growth of juvenile E. complanata mussels 10 months after exposure was also compared. Toxicity was determined after 12 h exposures at maximum concentrations from 2- to 2.5- fold higher than the LC99 for sea lamprey larvae. A logistic model was used to estimate the probability of survival among treatments, trials, species, and sizes. Mortality was minimal in all test concentrations of TFM alone and the TFM/1% niclosamide combination. Estimated survival decreased 6% for each unit increase in the relative toxicity of TFM. Survival was greater for E. complanata than for P. cataracta, and for adults relative to juveniles. Lampricide treatment caused narcotization of both mussels (defined as having gaped shells and an extended foot) in concentrations greater than or equal to LC99 for sea lamprey larvae and narcotization ranged from 0-50% among treatments. Recovery from narcosis was apparent by 12 h post-exposure and complete by 36 h post-exposure. The rate of growth of E. complanata over the 10-month post-exposure period did not vary among treatments.

Journal of Great Lakes Research

Effects of water temperature and pH on toxicity of terbufos, trichlorfon, 4-nitrophenol and 2,4-dinitrophenol to the amphipod Gammarus pseudolimnaeus and rainbow trout (Oncorhynchus mykiss)

Acute toxicity tests were conducted to determine (a) the individual and interactive effects of water temperature (7, 12, 17°C), pH (6 5, 7 5, 8 5, 9 5), and time on the toxicity of terbufos, trichlorfon, 4 nitrophenol, and 2,4-dinitrophenol to rainbow trout ( Oncorhynchus mykiss ) and the amphipod Gammarus pseudohmnaeus , and (b) the individual and interactive effects of water temperature and pH on chemical bioconcentration during acute tests with rainbow trout and Gammarus exposed to terbufos, 4 nitrophenol, and 2,4 dinitrophenol The toxicity of all four chemicals was significantly affected by pH in all tests, except for Gammarus exposed to terbufos The toxicity of terbufos to rainbow trout and Gammarus was less at pH 7 5 than at higher or lower pH The toxicity of both nitrophenols decreased as pH increased, whereas the toxicity of trichlorfon increased with pH The effect of pH on trichlorfon toxicity decreased with temperature Temperature significantly affected the toxicity of all four chemicals to both species Toxicity increased with temperature in all tests, except for rainbow trout exposed to nitrophenols, toxicity decreased as temperature increased for rainbow trout Chemical bioconcentration was also significantly af fected by temperature and pH and was directly related to toxicity in most tests Significant interactive effects between toxicity modifying factors were also frequently observed Temperature and pH effects on chemical toxicity need to be consid ered in chemical hazard assessment to ensure adequate protection of aquatic organisms

Environmental Toxicology and Chemistry

Effects of water temperature on the toxicity of 4-nitrophenol and 2,4-dinitrophenol to developing rainbow trout (Oncorhynchus mykiss)

Early-life-stage (ELS) toxicity tests were conducted to determine the effect of selected water temperatures on the toxicity of 4-nitrophenol and 2,4-dinitrophenol to rainbow trout ( Oncorhynchus mykiss ). NOECs were determined for growth and mortality at selected time intervals and water temperatures of 7, 12, and 17°C. As tests progressed, NOECs leveled to constant time-independent values that were similar for tests at each temperature. In 4-nitrophenol tests, the time-independent NOEC values at 7, 12, and 17°C, respectively, were 1.16, 1.20, and 1.16 mg/L for growth and 3.40, 3.38, and 2.20 mg/L for mortality. For 2,4-dinitrophenol, time-independent NOEC values at 7, 12, and 17°C, respectively, were 1.07, 0.50, and 0.80 mg/L for growth and 1.30, 1.89, and 1.60 mg/L for mortality. Temperature did, however, affect the rate at which time-independent NOECs were reached. More time was required to reach time-independent NOECs as temperature decreased. For example, the time-independent NOEC in 4-nitrophenol tests at 17°C was reached in 14 d, whereas it required 42 d at 7°C. The effect of temperature on toxicity must be considered in hazard assessment protocols to assess risk accurately and protect aquatic organisms adequately. Chronic toxicity tests are necessary to assess risk because acute toxicity tests cannot provide the information necessary to predict the long-term effects of factors such as temperature in natural environments.

Environmental Toxicology and Chemistry

Effect of the lampricide 3-trifluoromethyl-4-nitrophenol on the pink heelsplitter

The lampricide 3-trifluoromethyl-4-nitrophenol (TFM) is used to selectively kill sea lampreys (Petromyzon marinus ) in the tributaries of the Great Lakes. Over the years, TFM was tested most often on nontarget fishes and only occasionally on invertebrates, including freshwater mussels. We exposed pink heelsplitters (Potamilus alatus ) to TFM concentrations and exposure times similar to those in lampricide treatments. Tests were conducted in water similar in quality to the Poultney River, New York, a stream that contains pink heelsplitters and is scheduled for lampricide treatment in 1991. Mussels were exposed to TFM for either 12 or 24 h and observed daily in well water for 14 days. Ninety percent of the mussels exposed to 3.5 mg/L of TFM for 12 h survived, however, only 50% of the mussels exposed to that concentration for 24 h survived. TFM seems to narcotize or anesthetize mussels. Mortality of mussels exposed to 3.5 mg/L TFM for 12 h seemed to be 60% immediately after treatment, but the actual mortality was only 10% after a 14-day recovery period.

Resource Publication

Effect of pH on the toxicity of TFM to sea lamprey larvae and nontarget species during a stream treatment

Treatment of tributaries to the Great Lakes with the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) occasionally results in incomplete kills of sea lamprey larvae (Petromyzon marinus ) or excessive mortality of nontarget fish. In continuous-flow toxicity tests conducted on the Millecoquins River, Michigan, TFM remained selective for sea lamprey at the ambient stream pH and at an increased pH. At all but one concentration, TFM killed all sea lampreys and none of the target fish. Selectivity decreased when the pH was lowered by approximately 1 unit. TFM at the lowest tested concentration (2.3 mg/L) killed 100% of the sea lampreys, 50% of the rainbow trout (Oncorhynchus mykiss ), and 40% of the fathead minnows (Pimephales promelas ). When the Millecoquins River was treated at a concentration of 4.2 mg/L of TFM, all the caged sea lampreys were killed at the ambient stream pH (8.35). Treated stream water that was diverted through stainless steel tanks killed only 55% of the sea lampreys and none of the nontarget organisms when the pH was raised to 9.23. All of the sea lampreys and nontarget organisms were killed when the pH of the treated water was lowered to 7.25. These results indicate that diurnal changes in stream pH of approximately 1 pH unit can either cause TFM to become toxic to nontarget organisms or render the treatment ineffective for killing sea lampreys.

Technical Report

Removal of benzocaine from water by filtration with activated carbon

Benzocaine is a promising candidate for registration with the U.S. Food and Drug Administration for use as an anesthetic in fish culture, management, and research. A method for the removal of benzocaine from hatchery effluents could speed registration of this drug by eliminating requirements for data on its residues, tolerances, detoxification, and environmental hazards. Carbon filtration effectively removes many organic compounds from water. This study tested the effectiveness of three types of activated carbon for removing benzocaine from water by column filtration under controlled laboratory conditions. An adsorptive capacity was calculated for each type of activated carbon. Filtrasorb 400 (12 × 40 mesh; U.S. standard sieve series) showed the greatest capacity for benzocaine adsorption (76.12 mg benzocaine/g carbon); Filtrasorb 300 (8 × 30 mesh) ranked next (31.93 mg/g); and Filtrasorb 816 (8 × 16 mesh) adsorbed the least (1.0 mg/g). Increased adsorptive capacity was associated with smaller carbon particle size; however, smaller particle size also impeded column flow. Carbon filtration is a practical means for removing benzocaine from treated water.

Progressive Fish-Culturist

Control of nuisance populations of crayfish with traps and toxicants

Crayfish have long been a nuisance in fishrearing ponds at fish hatcheries. The rusty crayfish ( Orconectes rusticus ) has displaced endemic species and caused serious declines of aquatic plants in some ponds and lakes in the midwestern USA. We attempted to evaluate the effect of intensive trapping on a crayfish population and to identify a selective chemical control agent and evaluate its effectiveness under field conditions. A crayfish population in a small pond was suppressed but not eliminated by trapping; adults were effectively harvested but efficiency diminished sharply as the population declined. Of 19 chemicals tested as possible control agents for crayfish, a synthetic pyrethroid (Baythroid) was by far the most toxic; 25 μg/L produced a complete kill of crayfish in the pond and was also the most selective for crayfish in laboratory tests.

Progressive Fish-Culturist

Relation of pH to toxicity of lampricide TFM in the laboratory

In the control of larval sea lamprey (Petromyzon marinus ) with 3-trifluoromethyl-4-nitrophenol (TFM) in tributaries of the Great Lakes, occasional kills of other fishes have caused concern about the effects of the chemical on non-target organisms. Stream treatment rates have been based on previous application rates, alkalinity measurements, results of on-site toxicity tests, or combinations of these. Laboratory studies in 1987 showed that pH is the primary factor that affects the toxicity of TFM (the lower the pH, the greater the toxicity): even small changes in pH alter the toxicity, whereas substantial changes in alkalinity have little effect. In 12-h exposures, the 96-h LC50 for TFM to rainbow trout (Salmo gairdneri ) ranged from about 0.9 mg/L at pH 6.5 to > 100 mg/L at pH 9.5, but (at pH 7.5) the LC50's differed little at total alkalinities of about 18 mg/L and 207 mg/L. Decreases in pH as small as 0.5 pH unit caused nontoxic solutions to become toxic to rainbow trout. Some kills of non-target fish during stream treatments were reportedly caused by decreases in pH, and (conversely) that some stream treatments for sea lampreys were ineffective because pH increased.

Technical Report