Arthur J. Niimi

Increased cellular apoptosis after chronic aqueous exposure to nonylphenol and quercetin in adult medaka (Oryzias latipes)

Increasing evidence suggests that sublethal effects of natural or xenobiotic chemicals in the environment may be mediated via the stimulation of apoptosis. To investigate whether apoptosis can be induced in fish by weakly estrogenic and androgenic chemicals, adult male Japanese medaka (Oryzias latipes) were exposed to 100 ppb of the estrogenic alkylphenol, 4-nonylphenol, and adult female medaka were exposed to 100 ppb of the aromatase-inhibiting bioflavonoid, quercetin, for 6 weeks. Exposure to nonylphenol and quercetin had no significant effect on the length, weight or condition factors compared to solvent (acetone) controls in male or female medaka. Apoptosis was evaluated in blinded histological sections of whole medaka using terminal dideoxynucleotidyl transferase dUTP nick end labeling (TUNEL) that labels nuclei of cells containing apoptotic (fragmented) DNA. There was a six-fold greater extent of apoptosis in spermatocytes, Sertoli cells and Leydig-homologue cells, but not in spermatids of testes from nonylphenol-exposed male medaka compared to testes of solvent controls. No significant differences in the extent of apoptosis were detected in intestine, liver or kidney from the same male fish. Quercetin-treated female medaka had a significantly increased number of atretic ovarian follicles, but no significant differences in the extent of apoptosis in intestine, liver or kidney. These results suggest that nonylphenol caused testicular degeneration via increased testicular cell apoptosis, while quercetin may be ovotoxic via increased follicular atresia.

Review of Biochemical Methods and Other Indicators to Assess Fish Health in Aquatic Ecosystems Containing Toxic Chemicals

Abstract Whole animal, cellular, biochemical, and genetic studies were reviewed to identify methods that could be used to assess the health of fish from a field perspective. The survey, which focused primarily on the effects of chemical exposure, indicated most techniques would not be suitable for field use because threshold response levels were substantially higher than most environmental chemical concentrations. These responses could also be influenced by biological and environmental factors which increase the difficulties in determining if a change in a biological measurement is actually detrimental to fish. Several indicators would be required to determine the well-being of a natural fish population because the causes are likely to be of multiple origin. Advancements in assessment techniques can likely be made at the cellular and genetic levels because laboratory and field studies indicate these indices are the most sensitive to chemical exposure. Chemical impacts on fish population health would likely occur during reproduction as this process appears vulnerable to chemical exposure.

Low salinity residual ballast discharge and exotic species introductions to the North American Great Lakes

Exotic species introductions to the North American Great Lakes have continued even though ballast water management strategies were implemented in the early 1990s. Overseas vessels that arrive with little or no exchangeable ballast on board have been suspected to be an important source for discharging low salinity ballast containing low salinity tolerant organisms in this region. Residual ballast averaged 18.1+/-13.4 per thousand salinity among 62 samples taken primarily from bottom tanks on 26 vessels that entered the Great Lakes in 1999 and 2000. Sampling of 2-4 tanks each on nine vessels indicated all carried at least one tank of residual ballast of </=5 per thousand salinity. Many of these transits originated from the northeast Atlantic, Mediterranean and Black Sea regions which have been the probable source for many of the more recent introductions to this region.

Induction of hepatic EROD in fish exposed to leachates from wood pulp

Aqueous leachates from softwood and hardwood pulp collected from two different pulping stages in a kraft mill (i.e. pre- and post-oxygen delignification) were assessed for their ability to induce hepatic ethoxyresorufin-O-deethylase (EROD) in rainbow trout (Oncorhynchus mykiss). Immature rainbow trout were exposed to aqueous leachates from wood pulp for 21 days in a flow-through system. The leachates from softwood pulp collected at both pulping stages and leachates from pre-oxidation hardwood pulp elevated EROD activities 2.5 to 6-fold above reference fish, beginning at 7 days from the start of exposure. The EROD activity remained elevated in these treatments throughout exposure, but declined rapidly during a 14 day post-exposure period. Leachate from the softwood pulp appeared to be a more potent EROD inducer than leachate from hardwood pulp. The results of this study indicate that relatively hydrophilic chemicals capable of inducing MFOs in fish are present in wood pulp even before extensive mill processing.

Influence of Vessel Transit Patterns on Developing a Ballast Water Treatment Strategy for Exotic Species

Abstract The accelerating rate of dispersion of exotic aquatic species on a global scale has prompted a need to develop methods to treat ballast water. Vessel transits patterns were assessed to determine the influence of this variable on the development of a ballast water management strategy. Analyses of data sets from four North American ports that included 464 to 2537 different vessels that made 2076 to 8056 visits from overseas to each port over a 3 to 9 years interval indicated two consistent trends. The most important was 45–71% of the vessels visited a port once over the period monitored. Also, less than 20% of the vessels visited a port regularly on an annual basis. The low frequency of visits by individual vessels could influence the design and application of ballast water treatment options.

Economic and Environmental Issues of the Proposed Extension of the Winter Navigation Season and Improvements on the Great Lakes-St. Lawrence Seaway System

The Governments of the United States and Canada must decide in the near future if vessel and cargo transit on the Great Lakes-St. Lawrence Seaway (GL-SLS) is to be operated at capacity or the system be improved to accommodate the projected increases. Portions of the GL-SLS could approach operating capacity in the mid-1980s and options to increase capacity include extending the present 81/2 month navigation season to 11–12 months, and/or upgrading existing facilities to accommodate larger vessels. The U.S. Army Corps of Engineers is one of the few groups which has examined this issue in depth, and has concluded that it is technically and economically feasible to increase the capacity. The economic and environmental issues of the Corps proposal are discussed as viewed from a Canadian perspective. Total cost of the proposed improvements is difficult to establish because some economic costs and benefits can be identified while others are less obvious, and environmental costs and benefits have not been adequately assessed to provide the basis for a rational judgment. The major economic and environmental concerns are discussed to demonstrate the need for more information that would be required by both countries to make an equitable decision. An evaluation of the proposed improvements to the GL-SLS on the environmental resources of Canada is presented. Environmentally sensitive areas such as shorelines, wetlands, and inshore and shallow areas along the interconnecting waterways have been characterised and it is evident that a large percentage of these areas occur within Canadian waters. Furthermore, most of the major capital improvements proposed for the system are in Canada. In view of this, it is suggested that the cost-sharing arrangement between the U.S. and Canada proposed by the Corps of Engineers for improvements on the GL-SLS would not be in the best interest of Canada.

Distribution and Bioaccumulation of Chlorinated Diphenyl Ethers in a Contaminated Embayment of Lake Ontario

Polychlorinated diphenyl ethers (PCDEs) are halogenated aromatic hydrocarbons that have structural similarities to polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans. PCDEs have been detected in piscivorus fish, fish eating birds and humans, but little is known about the transfer of these compounds through aquatic ecosystems. At sampling stations in the contaminated area of Whitby Harbour on the north shore of Lake Ontario, mean concentrations of total PCDE congeners in sediment were between 622 and 1,929 ng/g dry weight. Analysis of semipermeable membrane devices (SPMDs) deployed at several stations around the harbor indicated that PCDEs were distributed homogeneously in the water. Mean total PCDE concentrations in biota were as high as 672 ng/g wet weight (105 μg/g lipid) in white sucker (Catostomus commersoni) and 791 ng/g wet weight (55 μg/g lipid) in brown bullheads (Ameiurus nebulosus). The patterns of 45 PCDE congener analytes differed among the SPMDs, sediment, and biota, but between invertebrates and fish the congener patterns were relatively homogeneous. Bioamagnification factors (BMFs) calculated for total PCDEs in a simple benthic food chain (oligochaetes to white suckers) and a simple pelagic food chain (plankton to pumpkinseed) indicated that there was biomagnification, with BMFs < 50 on a lipid-normalized basis and BMFs < 5 on a wet weight basis. For individual PCDE congeners, there was a slight trend to increasing BMFs with increasing chlorine substitution.

Is Trypanoplasma Salmositica Present in Lake Ontario Salmonids

During the period June-October 1981, fish, including lake trout (Salvelinus namaycush), brown trout (Salmo trutta), rainbow trout (Salmo gairdneri) and coho salmon (Oncorhynchus kisutch), were collected from four locations on Lake Ontario. In addition, juvenile coho salmon reared from Lake Ontario fish eggs and maintained in a hatchery were collected. Subsequently, air-dried blood smears were stained with Leishman-Giesma and examined under oil emersion for Trypanoplasma salmositica. In this study of 131 fish, no T. salmositica were found. From these findings it may be assumed that T. salmositica are either rare or not present in Lake Ontario salmonids.