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W.E. Johnson

Publications and source records attributed to W.E. Johnson.

4 recordsLinked to original sources
USGS2004

Organochlorine pesticides and thiamine in eggs of largemouth bass and American alligators and their relationship with early life-stage mortality

Thiamine deficiency has been linked to early mortality syndrome in salmonids in the Great Lakes. This study was conducted to compare thiamine concentrations in American alligators ( Alligator mississippiensis ) and Florida largemouth bass ( Micropterus salmoides floridanus ) eggs from sites with high embryo mortality and high exposure to organochlorine pesticides (OCPs) (Lakes Apopka and Griffin, and Emeralda Marsh, Florida, USA) to those from sites that have historically exhibited low embryo mortality and low OCPs (Lakes Woodruff and Orange, Florida). During June-July 2000, 20 alligator clutches were collected from these sites, artificially incubated, and monitored for embryo mortality. Thiamine and OCPs were measured in one egg/clutch. During February 2002, 10 adult female bass were collected from Emeralda Marsh and Lake Woodruff and mature ovaries analyzed for thiamine and OCP concentrations. Although ovaries from the Emeralda Marsh bass contained almost 1,000-fold more OCPs compared with the reference site, Lake Woodruff, there were no differences in thiamine concentrations between sites (11,710 vs. 11,857 pmol/g). In contrast, alligator eggs from the reference site had five times the amount of thiamine compared with the contaminated sites (3,123 vs. 617 pmol/g). Similarly, clutches with > 55% hatch rates had significantly higher concentrations of thiamine compared with clutches with <54% hatch rates (1,119 vs. 201 pmol/g). These results suggest that thiamine deficiency might be playing an important role in alligator embryo survival but not in reproductive failure and recruitment of largemouth bass. The cause(s) of this thiamine deficiency are unknown but might be related to differences in the nutritional value of prey items across the sites studied and/or to the presence of high concentration of contaminants in eggs.

Florida↗
USGS2003

Aqueous-phase disappearance of atrazine, metolachlor, and chlorpyrifos in laboratory aquaria and outdoor macrocosms

Dissipation processes are described for a combination of commonly used pesticides—atrazine (6-chloro-4-ethylamino-6-isopropylamino- s -triazine), metolachlor (2-chloro- N -[2-ethyl-6-methyl-phenyl]- N -[2-methoxy-1-methylethyl] acetamide), and chlorpyrifos ( O-O diethyl O -[3,5,6-trichloro-2-pyridinyl] phosphorothioate)—in a laboratory and outdoor pond systems. Dosing rates and timing were designed to duplicate those common in the mid-Atlantic Coastal Plain, USA. Treatments ranged from 2 and 2.5 mg/L to 0.2 and 0.25 mg/L respectively for atrazine and metolachlor, and chlorpyrifos was added at 1.0 and 0.1 mg/L in the aquaria and at 0.1 mg/L in the outdoor macrocosms. Chlorpyrifos disappearance was rapid in all of the systems and followed a two-phase sequence. Initial half-lives varied from 0.16 day to 0.38 day and showed similar rates in the aquaria and the outdoor systems. The second phase of the chlorpyrifis loss pattern was slower (18–20 days) in all the treatments except for the low herbicide treatment in the outdoor test, where it was 3.4 days. Compared to the outdoor system, herbicide losses were much slower in the aquaria, e.g., 150 days for atrazine and 55 days for metolachlor, and no appreciable loss of herbicide was apparent in the high-treated aquaria. In the outdoor systems, the half-lives for the low herbicide treatment were 27 days and 12 days, respectively, for atrazine and metolachlor, and 48 and 20 days, respectively for the high herbicide-treated pond. Very low levels of CIAT (6-amino-2-chloro-4-iso-propylamino- s -triazine) and CEAT (2-chloro-4-ethylamino-6-ethylamino- s -triazine), degradation products of atrazine, were observed in the outdoor studies.

Archives of Environmental Contamination and Toxico↗
USGS2002

An evaluation of biomarkers of reproductive function and potential contaminant effects in Florida largemouth bass (Micropterus salmoides floridanus) sampled from the St. Johns River

The objective of this study was to describe and compare several reproductive parameters for Florida largemouth bass ( Micropterus salmoides floridanus ) inhabiting the St. Johns River and exposed to different types and/or degrees of contamination. Welaka was selected as the reference site in this study because of its low urban and agricultural development, Palatka is in close proximity to a paper mill plant, the Green Cove site is influenced by marine shipping activities and Julington Creek site receives discharges of domestic wastewater and storm water runoff from recreational boating marinas. For this study, bass were sampled both prior to (September 1996) and during the spawning season (February 1997). In order to characterize chemical exposure, bass livers were analyzed for up to 90 trace organics and 11 trace metal contaminants. Reproductive parameters measured included gonadosomatic index (GSI), histological evaluation of gonads and plasma concentrations of vitellogenin (VTG), 17β-estradiol (E 2 ) and 11-ketotestosterone (11-KT). In general, the sum of organic chemicals was highest in livers from Palatka bass and bass from Green Cove and Julington Creek had higher hepatic concentrations of low molecular polycyclic aromatic hydrocarbons and polychlorinated biphenyls when compared to fish from Welaka. Metals were more variable across sites, with highest mean concentrations found in bass from either Julington Creek (Ag, As, Cr, Cu, Zn) or Welaka (Cd, Hg, Pb, Se, Tn). Female bass from Palatka and Green Cove had lower concentrations of E 2 , VTG and lower GSI in relation to Welaka. Males from Palatka and Green Cove showed comparable declines in 11-KT in relation to males from Julington Creek and GSI were decreased only in Palatka males. These results indicate a geographical trend in reproductive effects, with changes being most pronounced at the site closest to the paper mill (Palatka) and decreasing as the St. Johns River flows downstream. Since reproductive alterations were most evident in bass sampled from the site closest to the paper mill discharge, it is possible that exposure to these effluents might explain at least some of the results reported here. However, the presence of reproductive alterations in fish sampled at a considerable distance from the mill discharge (Green Cove, 40 km) would suggest exposure to chemicals released from sources other than the paper mill plant. It is clear that additional studies are needed to evaluate the potential impact of these reproductive changes in populations of Florida largemouth bass inhabiting the St. Johns River.

Florida↗