Mike Dickman

Evidence of Teratogens in Sediments of the Niagara River Watershed as Reflected by Chironomid (Diptera: Chironomidae) Deformities

Chironomids from two locations in an IJC “Area of Concern” in the Niagara River watershed and from one site in Lake Huron were sampled and classified as either normal or abnormal based on their menta (“teeth”) deformities. The two Niagara River sites were the Kings Bridge reference site and the Kane Dock coal tar contaminated area. The latter site was immediately downstream of an abrasives company located about 800 m downstream of the Kings Bridge reference site. Among the 739 chironomids sampled from the Kings Bridge reference site, 3.1% (23) possessed menta with deformities. This deformity frequency was similar to the 2.8% deformity frequency observed in a clean water site in Lake Huron. Chironomids removed from the coal tar contaminated site displayed a deformity frequency of 14%. The dominant invertebrate in the coal tar (PAH) contaminated sediments was the midge (Chironomus anthracinus), a non-biting fly larva referred to as a blood worm. Thus there was a significantly higher frequency of menta deformities downstream of the abrasives manufacturers discharge than at the Kings Bridge reference site (Students “t” test, P < 0.05). The chironomids at the contaminated site were themselves contaminated with elevated levels of fifteen different PAHs. The PAH levels in the bodies of the deformed chironomids were higher than the levels in the undeformed chironomids collected at the same site. When over 200 chironomids with an average deformity frequency of 7.7% were taken from the PAH contaminated site and placed in clean (PAH uncontaminated) sediments taken from the Kings Bridge Park reference site, the resulting F1 generation displayed a mentum deformity frequency of 4%. These rearing experiments indicated that few, if any, of the observed C. anthracinus menta deformities were passed on to the next generation.

Physico-chemical characteristics and origin of hypersaline meromictic Lake Garrow in the Canadian High Arctic

Garrow Lake (75° 23′ N; 96° 50′ W), located 3 km from the southern tip of Little Cornwallis Island and 6.7 m above mean sea level, is a meromictic ecto-creno-cryogenic lake with an area of 418 ha and a maximum water depth of 49 m. The thermal stratifieation of this lake is mesothermic (heliothermic). Some of the solar energy that penetrates through the 2 mice cover is stored for a long period of time in the upper level of the monimolimnion, under a greenhouse effect due the water density gradient. The energy transfer (0.06° Cm−1) by conduction toward the bottom sediments is very constant from one year to the next and is likely to prevent the presence of permafrost under this water body.

Paleoecological reconstruction of changes in the productivity of a small, meromictic lake in Southern Ontario, Canada

Some aspects of the paleoproductivity of meromictic Crawford Lake, near Toronto, are inferred from a study of its sedimentary pigments, and diatoms. Several stages of lake development are observed over the 35 cm-deep sediment core removed from the center of Crawford Lake. Evidence of changes in lake productivity during the last 300 years was reflected by significant stratigraphic sediment pigment changes which were associated with European settlement in the Crawford Lake watershed and recent alterations associated with the areas operation by the Conservation Authority (1969 — present). One of the most important factors correlated with paleoproductivity was land clearance (mainly logging of white oak and pine). Deforestation during the last century is correlated with an increase in the amount of algal pigments deposited in the lakes sediments during the 1800s. During the last 10 years a striking increase in the accumulation of chlorophyll derivatives was observed. This is correlated with a dramatic increase in the number of visitors to the lake.Stratigraphic changes in the ratio of cyanobacterial to phototrophic bacterial pigment accumulation are used to infer changes which occurred during the shift from mesotrophy to eutrophy in Crawford Lake.

Correlation of surface sediment diatoms with the present lake water pH in 28 Algoma lakes, Ontario, Canada

The surface sediment diatom analysis of 28 Algoma lakes (pH 4.40–8.13) indicates that even though each lake has a widely different aquatic environment and characteristic diatom assemblage, a definite relationship exists between the lake water pH and their diatom assemblages. In the acidic lakes acidobiontic and acidophilous diatom species predominate whereas in circumneutral and alkaline lakes circumneutral and alkaliphilous diatoms were most common. Cluster analysis of the pH indicator diatom assemblages grouped the study lakes into three distinct cluster groups. These groups also closely corresponded to lake water pH. On the basis of published ecological information as well as their presence in our study lakes, the pH indicator status of a number of diatom taxa have been discussed. A detailed listing of the diatom taxa identified and their pH indicator status is provided in order to facilitate their use in future diatom-inferred pH studies.

Physicochemical Limnology of Meromictic Saline Lake Sophia, Canadian Arctic Archipelago

The basic physicochemical characteristics of a Canadian High Arctic deep meromictic and mesothermic lake with an open drainage system are presented. The monimolimnetic salinity of Lake Sophia reaches 58 ± and its mid-water temperature is perennially at 12°C. This type lake is most commonly found in Antarctica, while so far only two have been reported from the Canadian Arctic.The salts of the monimolimnion seem to have originated during the postglacial marine submergence mainly from marine waters trapped within the ancient lake basin and beneath the surface of the area. It is most likely that the concentration of salts by freezing-out of ions from the underground relict pore seawater was progressively brought about by the encroachment of permafrost on the newly uplifted lake surrounding. The water insulating layer could have caused the formation of a talik beneath the lake basin, which subsequently favored the displacement of the underground saline water toward the bottom of the lake. With time, some of th...

Gonadal neoplasms in wild carp-goldfish hybrids from the Welland River near Niagara Falls, Canada

The frequency of gonadal neoplasms in carp-goldfish hybrids was associated with the number of industrial outfalls to the Welland River. In a rural agricultural area without industrial discharges, upstream of the City of Welland, there were no observations of tumors in 1066 fish collected during the year-long study. In areas with moderate industrial loading, over ten percent of the carp-goldfish hybrids displayed gonadal neoplasms. In the section of the Welland River which received the largest quantities of municipal and industrial wastes neoplasm frequency in hybrids was 48%. Among sexually mature carp-goldfish hybrids, 80% displayed gonadal neoplasms in the most highly polluted portion of the Welland River.All neoplasms were confined to the gonadal tissues of adult hybrids, none were found in juvenile fish. The Fisher Exact Probability comparison of the frequency of neoplasms in adult carp-goldfish hybrids captured above and below the industrialized portion of the Welland River indicated that a significantly higher number of these fish with neoplasms occurred below the industrialized area (N = 13, p = 0.035).

Impact of Tilapia Grazing on Plankton Composition in Artificial Ponds in Guanacaste, Province, Costa Rica

ABSTRACT Twenty-seven shallow tilapia culture ponds, having fish densities of 0.1 to 12 individuals · m−2 were studied in Guanacaste Province, Costa Rica. Temporal changes in plankton community structure following the emptying and subsequent filling of each pond were noted. In general, newly filled ponds were initially colonized by microflagellates, which in turn were replaced by green and finally blue green algae. Microcystis aeruginosa frequently became the dominant phytoplankter. Its density was correlated with both high tilapia densities and low zooplankton concentrations. When tilapia densities were maintained below 0.5 fish · m−2, the copepod Mesocyclops leukartii dominated the zooplankton community, and algal biomass was moderate. At higher tilapia densities, rotifers replaced copepods as the dominant zooplankters. When tilapia densities exceeded two adult fish m−2, negligible zooplankton levels were attained, and phytoplankton densities reached their highest levels (>2 × 10 cells · ml−1). At these...

Changes in 13C content of the organic component of lake sediments during the last 500 years in Crawford Lake, South Ontario, Canada

The major cyanobacteria in Crawford Lake are benthic mat forming Lyngbya and Oscillatoria and not phytoplankton. The eutrophication of the lake has resulted in a decline in the mat forming cyanobacteria as inferred from palaeopigment analyses of the core from this lake. In previous palaeolimnological studies the concentrations of oxillaxanthin and myxoxanthophyll have been used as correlates with lake trophic levels. High concentration of oscillaxanthin and myxoxanthophyll were interpreted as indicating eutrophic conditions prevailed. Our results indicated that when Crawford Lake was most eutrophic little oscillaxanthin and myxoxanthophyll was produced. High values of δ13C at the depth of 34–48 cm (1500–1760 A. D.) were related to a dense population of benthic Oscillatoria and Lyngbya living on the bottom of the lake during that period. The Oscillatoria and Lyngbya utilize bicarbonate as a source of inorganic carbon. Carbonate has a high δ13C value. Very low δ13C values were found at 0–7 cm (1955–1992 A. D.) in the Crawford sediment core at the time when phyto- plankton dominated the core. Phytoplankton are enriched in 12C by photosynthetic assimilation of CO2.

The impact of the Cyanamid Canada Co. discharges to benthic invertebrates in the Welland River in Niagara falls, Canada

In 1986, the International Joint Commission (IJC) recommended that the Niagara River watershed should be declared an Area of Concern (AOC). This IJC recommendation was ratified by the 4 signatories of the Great Lakes Water Quality Agreement. In order to delist an AOC, it is necessary to locate any areas of impairment within the watershed and carry out remediation projects that permit uses that were previously impaired. To this end we attempted to determine whether or not the sediments at 7 study sites near the Cyanamid Canada (Chemical) Co. were contaminated at levels that would result in the impairment of the natural biota which inhabit the watershed.The Cyanamid Canada (Chemical) Co. discharges ammonia wastes, cyanide, arsenic and a variety of heavy metals into treatment systems which ultimately discharge to the Welland River, the major Canadian tributary to the Niagara River. This portion of the Welland River near the factory was designated a Provincially significant (Class one) wetlands by the Ontario Ministry of Natural Resources. In 1986, the mean discharge to a creek from Cyanamid Canada Co. was 27,342 m3 per day (MOE, 1987). Similar discharge volumes occurred in 1989. In 1991, the total discharge was 25,000 m3 per day (MOE, 1991).The majority of the benthic invertebrates collected from the study area were pollution tolerant taxa (e.g., sludge worms constituted 68% of all the organisms collected). The lowest chironomid densities were observed at stations 1, 2, and 4, which were the only stations situated close to Cyanamids discharge pipes. The absence, of clams and mayflies which burrow to greater depths than do chironomids and sludge worms, probably reflects the inability of the deeper dwelling burrowers to tolerate the contaminants which we recorded at these 3 stations. The absence of all crustaceans from these same 3 stations (stations 1, 2 and 4) when coupled with their low biotic diversity and the elevated heavy metal concentrations in the sediments were cause for concern. In addition, stations 2 and 4 displayed the highest frequency of chironomid mentum deformities.Stations 1 and 2 were located near a pipe which was one of Cyanamid Canada Companys major discharge point sources to the Welland River until a court order in 1980 stopped the company from discharging toxic material to the Welland River via that pipe. Elevated levels of cobalt (10 times above background), molybdenum (6 times above background), nickel (8 times above back-ground), tungsten (284 times above background) and zinc (20 times above background) near the abandoned discharge pipe were correlated with the presence of pollution tolerant chironomid taxa such as Polypedilum and Procladius. The highest sludge worm densities were also observed at the abandoned pipe site which was the only site where oily wastes were found in the sediments.Among the 1,275 chironomids taken from the seven Cyanamid Canada stations, the great majority were pollution tolerant taxa. The low biotic diversity and the presence of considerable numbers of pollution tolerant benthic macroinvertebrates in combination with the chemical evidence of pollutants in the sediments near many of these Cyanamid discharge sites were reasons for classifying these sites as ‘impaired’ as defined by the International Joint Commission.