Lawrence River System Research Articles

Seasonal patterns of atrazine loading for the St Lawrence River (Canada) and its tributaries

The annual variability in atrazine concentrations and loadings have been studied for the St Lawrence River (Canada) and four of its tributaries. Hydrological parameters appear to be the principal controls on the loadings of atrazine in the St Lawrence River system throughout the year, except during the post-application period. In terms of the annual variability of loadings, prior to the application period, the spring freshet coincided with a major pulse of atrazine. A post-application peak load of atrazine was detected in the main river as well as in its tributaries. During the fall, atrazine loadings increased again. The results show that atrazine inputs to the system can be detected long after application. Average loadings in 1990 and 1991 were 7.7 and 4.4 kg/d in the St Lawrences River, and 0.4 and 0.2 kg/d in the tributaries studied. The seasonal variation of atrazine concentrations in surface waters of the tributaries was consistent with the temporal distribution reported in the literature, viz. peak concentrations during the post-application period. There was also an increase in concentrations in the main river channel during the fall, reflecting the fact that the main river also receives inputs from the Great Lakes and not only from proximate agricultural sources. The annual variability in atrazine concentration and loading in the tributaries was directly related to the proximity of agricultural sources. Average concentrations in 1990 and 1991 were 10.4 and 3.4 ng/l in the St Lawrence River, and 31.1 and 27.9 ng/l in the tributaries. The persistence of atrazine is believed to be a key element controlling its dynamics in these aquatic systems. The results demonstrate the widespread dispersion of atrazine in this river basin, with similar responses and seasonal trends being exhibited throughout.

Comparative study of contaminants in the mudpuppy (amphibia) and the common snapping turtle (reptilia), St. Lawrence River, Canada

Levels of organochlorine pesticides, polychlorinated biphenyl (PCB) congeners and mercury were measured in mudpuppy bodies, livers and gonads and in snapping turtle eggs to determine how the composition and concentration of these bioaccumulated contaminants differ between the two species. Furthermore, the geographic variation in contamination patterns were examined between the highly polluted St. Lawrence River and the much less polluted Ottawa River, Canada. Principal component analysis performed with 69 tissue samples (30 samples of mudpuppy tissues and 39 turtle egg clutches) indicated distinct contamination patterns in the two species for PCB congeners; PCB congener composition in mudpuppies resembled the pattern reported for fish while the turtle pattern was more akin to the bird pattern. This could be related to the metabolic capacity of each species. The organochlorine pesticide contamination profile was also species-specific although highly variable among locations. Contamination profiles were similar for mudpuppy gonads and carcasses but lipidweight basis concentrations were often a little higher in gonads. In both species, geographic variations in contamination patterns were noticeable and significant differences in contamination levels were detected between Ottawa River and St. Lawrence River samples. However, in both species, concentrations varied considerably within a single location. Sources of variability are discussed although the basic life history of these species in the St. Lawrence River system is relatively unknown.

Evaluation of the role of submerged plant beds in the metal budget of a fluvial lake

In a study of a large fluvial lake (Lake St. Pierre, St. Lawrence River system, Quebec), we have determined the biomass of the submerged vegetation (dominated by Vallisneria americana and Potamogeton spp) during the peak seasonal biomass (August) and senescence (October), and have estimated the content of Cd, Cr, Cu, Ni, Pb and Zn in the above-ground portions of these plants. Multispectral remote sensing data (MEIS-II) were used to extrapolate from point measures of biomass (g m−2) to the entire area of the lake (Lavoie et al., 1991). By combining field information (biomass values and metal concentrations) with the more extensive remote sensing data base of biomass values, and by using geostatistical estimation techniques (kriging), we have estimated the seasonal storage of metals in Lake St. Pierre plants to be: 30 kg Cd, 89 kg Cr, 450 kg Cu, 280 kg Ni, 71 kg Pb and 2200 kg Zn. During the seasonal biomass peak, the quantities of Cd, Pb and Zn stored in the plants were higher than those dissolved in the water column, but much lower than those present in the surficial, recent sediments. Mass balance calculations for the summer months indicated that the ‘macrophyte’ compartment represented only a small proportion of the metals entering the lake: Cu and Ni, <1%; Cd and Zn, 2%; Pb, 4%. Senescence and the downstream drifting of plant material noted in October suggested that most of the metals associated with the above-ground parts of the submerged vegetation were not recycled within the lake, but instead were exported at the end of the summer.

Temporal variation of PCB concentrations in the St. Lawrence river (Canada) and four of its tributaries

Samples of water and suspended particulate matter were collected at two cross-sections of the St. Lawrence River and at the mouth of four of its tributaries regularly between March and November 1991, and analyzed for thirteen PCB congeners. Mean total PCB concentrations were similar in the St. Lawrence River and its tributaries at 1.33 ng/L. The highest concentrations were observed in the spring with an important fraction of the contamination in the dissolved phase during the spring snowmelt must likely due to the accumulation of contaminated snow and atmospheric dry deposition during winter. For the rest of the year, the concentrations are lower and the PCBs are essentially transported by the suspended particulate matter. The PCB concentrations measured in the St. Lawrence River system seem to be more a residual signal than due to point sources.

Structure and Dynamics of Photosynthetic Picoplankton across the Saltwater Transition Zone of the St. Lawrence River

Changes in the biomass, community structure, and activity of photosynthetic picoplankton (PP) were measured across the turbid, freshwater–saltwater transition zone (TZ) of the St. Lawrence River. The &lt;2 μm fraction of total Chl a dropped from 20–30% in mid-May to 15% in late June. Photosynthesis by the &lt;2.0 μm fraction in May surface waters contributed 6–38% of the total primary production. Picoplankton dropped from 8.4 × 106 (freshwater zone, FZ) to 3.7 × 106 cells∙L−1 (TZ) in mid-May and from 17 × 106 (FZ) to 5.8 × 106 cells∙L−1 (TZ) in late June. Results implied that the picoplankton were subject to increased losses (e.g., by protozoan grazing) in the TZ. Phycoerythrin-rich cyanobacteria (PEC) dominated the PP counts in mid-May, with phycocyanin-rich forms (PCC) contributing 4–13% of the cell concentrations. Six weeks later the PP community had shifted completely to PCC dominance (60–69% of total counts). In late summer, PP contributed 6–56% of the planktonic Chl a in the St. Lawrence River system. There were large variations in the PEC/PCC ratio and the proportion of eukaryotic PP along certain reaches of the river. These observations underscore the spatially and temporally dynamic character of PP communities in the river–estuary environment.

Under‐ice observations of behavior of selected native and exotic fishes of the St. Lawrence river system

AbstractWinter behavior of two native fishes (yellow perch, Perca flavescens, and killifish, Fundulus heteroclitus) and an exotic (goldfish, Carassius auratus) were studied in an outdoor experimental pond to quantify and link behavior to environmental conditions, and to identify interactions among the species that now co‐occur in the wild. Killifish had high mortality and were not observed. However, contrary to our predictions, perch and goldfish had good overwinter survival and remained active in winter, and neither species spent most of their time in the warmest layer of the water column. Only two instances of aggression were seen: in both, goldfish charged perch. Both species were found principally in groups (schools); goldfish spent 18% of their time in multispecies groups. © 1994 Wiley‐Liss, Inc.

Endocrine Responses as Indicators of Sublethal Toxic Stress in Fish from Polluted Environments

Abstract Development of new methods for detection of sublethal toxic effects of pollutants in aquatic organisms has become a focus of interest in ecotoxicology. The endocrine response to pollutants is an integral part of the homeostatic physiological processes activated in response to environmental stressors including pollutants. Changes in concentrations of hormones, particularly those regulating vital functions such as osmoregulation, energy metabolism, reproduction, or growth, may have potential as early warning indicators of toxic stress in fish. We review the recent literature in fish endocrine toxicology and illustrate the use of hormonal indicators in detection of acid stress in the brook trout. Salvelinus fontinalis, from lakes in the Canadian Shield, and of general toxic stress in the pike, Esox lucius, and the perch, Perca flavescens, from the St. Lawrence River system polluted by a mixture of chemicals.

Microscopic observations of the iron plaque of a submerged aquatic plant ( Vallisneria americana Michx)

The immediate interface between the root cell wall and the iron plaque of Vallisneria americana Michx (wild celery), a submerged freshwater plant collected in lakes of the St. Lawrence River system, Québec, Canada, was examined. Based on transmission electron microscope observations and X-ray diffraction data, the iron plaque of V. americana is composed mainly of amorphous Fe material (occurring as filaments and dispersed material) and some crystalline particles (needles and nodules) composed of goethite and/or lepidocrocite. Energy dispersive spectroscopy also revealed the presence of Mn-rich particles in the plaque. Impurities, such as quartz and clays, were present inside the root iron coating, as were micro-organisms (bacteria) which are postulated to play an indirect role in the deposition of iron oxyhydroxides on the root.

Movements and biological statistics of lake sturgeon (Acipenser fulvescens) populations from the St. Lawrence and Ottawa River system, Quebec

Our objective was to compare movements and biological statistics of lake sturgeon (Acipenser fulvescens) populations from two fluvial lakes on the St. Lawrence River, Lac Saint-Louis and Lac Saint-Pierre, which are main commercial fishing sectors, and from Lac des Deux Montagnes on the Ottawa River. Sturgeon can move freely among these three lakes. Lac des Deux Montagnes sturgeon differ from the other groups by their higher degree of sedentariness, slower growth, and lower condition factor. Lac Saint-Louis and Lac Saint-Pierre sturgeon are also sedentary, but some movement between the two lakes was observed. Sturgeon tagged on the Rivière des Prairies and Rivière L'Assomption spawning grounds, located in the central part of the study area, and also on pre- and post-spawning concentration sites, were recaptured throughout the St. Lawrence River, from Lac Saint-Louis to Lac Saint-Pierre. Length, weight, and age composition of the commercial catch, growth, and total mortality varied between Lac Saint-Louis and Lac Saint-Pierre. Higher commercial exploitation rates in the latter could be responsible for some differences. The management implications of these results are discussed.

Impaired cortisol stress response in fish from environments polluted by PAHs, PCBs, and mercury.

The cortisol stress response to capture was investigated in two species of fish (Perca flavescens and Esox lucius) from sites polluted by high levels of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and mercury, and from reference sites in the St. Lawrence river system. Fish from the reference sites exhibited the normal elevation of serum cortisol in response to the acute stress of capture and had large pituitary corticotropes. In contrast, fish from the most polluted sites were unable to increase their serum cortisol in response to the acute stress of capture and their pituitary corticotropes were atrophied. These results suggest that a life-long exposure to chemical pollutants may lead to an exhaustion of the cortisol-producing endocrine system, possibly as a result of prolonged hyperactivity of the system.

Genotoxicity in water and sediment extracts from the St Lawrence river system, using the SOS chromotest

Surface water and sediments from the St Lawrence River system (Québec region) were analysed for genotoxicity using the SOS Chromotest, as well as for their chemical concentrations of polycyclic aromatic hydrocarbons and heavy metals. Additionally, chlorobenzenes, polychlorinated biphenyls, organochlorinated pesticides, ammonia and nitrite concentrations in sediments were determined. Water and sediments sampled from twenty-five sites were initially partitioned into their aqueous and particulate phases by tangential flow filtration and centrifugation, respectively. Organic contaminants were extracted from the fractions with dichloromethane. For surface water, fifteen extracts of filtered water and seven of particulates, and for sediments one extract of pore water and three of particulates proved to be weakly genotoxic. All but one of the genotoxic responses observed in the surface water were obtained from samples taken from the highly industrial portion of the St Lawrence River system, with the strongest responses observed in Lake St Louis. Surface water genotoxicants partitioning favours the particulate fraction. Bottom particulates genotoxicity was 1000-fold weaker than suspended particulates, on a per unit weight basis. Additionally, whole sediments were extracted with a 10% dimethylsulfoxide-saline solution. The observed distributions of genotoxicity values did not correlate with observed concentrations of demonstrated SOS inducers, mutagens and/or carcinogens, nor with the presence of other toxic chemicals.

Geology of the Lake Ontario Basin: A Review and Outlook

Lake Ontario, located at the northern margin of the Appalachian Basin, occupies a deep trough cut by rivers and glaciers into early to mid-Paleozoic limestones and shales. It is still being affected by movements along faults which have probably been active since late Precambrian (more than 600 million yr ago), as evidenced by small faults, "pop-ups" (small domes and anticlines) involving bedrock, Pleistocene drift (glacial and nonglacial deposits) and recent lacustrine sediments, and many small earthquakes (up to intensity V in the Mercalli scale). Infrequent large earthquakes may damage buildings and trigger slumps along coastal bluffs and subaqueous lacustrine slopes. Fractures generated by such crustal movements may become pathways for groundwater and leakage of stored dangerous substances. The lake receives sands from shore erosion of Pleistocene drift and silts and clays from rivers crossing vast Pleistocene lacustrine plains subjected to agricultural practices. Some of the nearshore, subaqueous sand deposits cannot be readily exploited for aggregates because shore erosion may be triggered and valuable ecosystems can be destroyed. Clays mop up pollutants, in part storing them in depocenters such as lagoons, marshes, and the deep lacustrine basins, and in part exporting them to the St. Lawrence River system.

The Niagara River: A water quality management overview

The Niagara River constitutes part of the Laurentian Great Lakes and St. Lawrence River system which represents approximately 80% of North America's supply of surface fresh water. The river is a major source of water for industry, municipalities, recreation and power generation and is the link between Lakes Erie and Ontario. The river forms part of the Canada-U.S. border and falls under the jurisdiction of both countries.The massive industrialization of the region surrounding the river has led to a typical resource use conflict situation in which pollution of the river continues to be a major public concern.A number of constitutional, institutional and jurisdictional factors make the management of the Niagara River an involved and complicated matter. The interests, intent, philosophies, laws and regulations are not necessarily the same among the numerous jurisdiction involved. Despite these differences, however, Canada and the United States have succeeded in developing and implementing a model cooperative international management plan for the river. An overview of the main international aspects relating to the development and implementation of this plan, the Niagara River Toxics Management Plan, is presented.

Flow Distribution in the St. Lawrence River System at Wolfe Island, Kingston Basin, Lake Ontario

Determination of the mass output through the St. Lawrence River outflow system is an important component in computing a mass balance of chemical loadings in Lake Ontario. Toward this goal, during 1986 and 1987, a network of self recording current meter moorings were deployed in the main channels of the St. Lawrence River system in Lake Ontario. On two occasions in 1987, detailed Lagrangian experiments were carried out using a cluster of satellite drifters. The time series data from the current meter network and Lagrangian drifter experiments provided the horizontal and vertical distribution of currents that are adequate to compute the distribution of water transport through the St. Lawrence outflow. The flow distribution in the St. Lawrence River at Wolfe Island is approximately 55 percent in the south channel and 45 percent in the north channel. The total flow rate through the St. Lawrence River system from the present study is in good agreement with the direct measurements at the power plant control facilities at Cornwall.

Loadings of Selected Chemicals into the St. Lawrence River System from Lake Ontario, 1986/87

Abstract Determination of the mass output through the St. Lawrence River outflow system is an important component in computing mass balance of chemical loadings to Lake Ontario. The total flow rate in the St. Lawrence River System at the Wolfe Island area was calculated from detailed time series current meter measurements from a network of current meters and Lagrangian drifter experiments. This flow is roughly distributed in the ratio of 55% to 45% in the South and North channel, respectively. Loading estimates of selected chemicals have been made by combining the above transport calculations with the ongoing chemical monitoring data at the St. Lawrence outflow. A vertical gradient in the concentration of some organic and inorganic chemicals was observed. The measured concentration for some of the chemicals was higher during the summer months and also is higher in the South Channel than in the North Channel of the St. Lawrence River. These loading estimates are useful not only for modelling the mass balance of chemicals in Lake Ontario but also for serving as input loadings to the St. Lawrence River system from Lake Ontario.

Sea Lamprey (Petromyzon marinus) in the Lower Great Lakes

Sea lamprey (Petromyzon marinus) are established in each of the several discrete areas in the St. Lawrence River system between Lake Huron and the Moses–Saunders Power Dam (160 km below Lake Ontario) except for the Niagara River between Niagara Falls and Lake Ontario. However, chemical lampricide treatments are being used to control these populations only in Lake Ontario. Experimental introductions of trout and salmon in Lake Ontario between 1968 and 1971 were not successful. Survival was limited and the number of sea lamprey attack marks on the fish that did mature was very high. After the first round of lampricide treatments of most sea lamprey producing tributaries in 1972, survival of fish improved and lamprey attacks declined. Studies are being completed to determine the desirability of including Oneida Lake in the treatment schedule to prevent recruitment of sea lampreys from this area to Lake Ontario and to improve the fish populations of Oneida Lake. Treatment of Lake Champlain also is being studied by management agencies concerned with its fisheries. Lake St. Clair and Lake Erie and connecting waters, the Finger Lakes, and the St. Lawrence River below Lake Ontario do not appear to have sea lampreys in the numbers necessary to cause unacceptable levels of predation on fish populations and are not being considered for inclusion in the Great Lakes Fishery Commission control program at this time.Key words: sea lamprey, predation, abundance, history, Erie, Ontario, Oneida, Finger Lakes, Champlain