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Papers by Raymond Hesslein

Can J Fisheries Aquat Sci, 1980

Journal of Great Lakes Research, 2012

Nutrient enrichment leading to eutrophication of lakes is frequently attributed to increasing ant... more Nutrient enrichment leading to eutrophication of lakes is frequently attributed to increasing anthropogenic loading to the watershed. We use a phosphorus mass b.

Water Air Soil Pollut, 1990

ABSTRACT Six gamma-emitting isotopes, Se-75, Hg-203, Cs-134, Fe-59, Zn-65 and Co-60, were introdu... more ABSTRACT Six gamma-emitting isotopes, Se-75, Hg-203, Cs-134, Fe-59, Zn-65 and Co-60, were introduced simultaneously in a single epilimnetic addition to an oligotrophic lake on the Precambrian Shield of northwestern Ontario, Canada. Accumulation of each isotope was monitored in fathead minnow (Pimephales promelas) for 274 days. Isotope accumulation in blood, gill, gut, liver, kidney, spleen, gonad, brain, muscle and gut contents of lake trout (Salvelinus namaycush) was monitored for 352 days. Fish accumulated only traces of Fe-59. Isotopes which occured in water primarily in the charcoal-extracted fraction (Se-75 and Zn-65) were most readily accumulated by fish. Fathead minnow accumulated higher concentrations of all isotopes than lake trout. In lake trout, the highest concentrations of isotopes were found in the following tissues: Se-75, liver; Hg-203 and Co-60, kidney; Cs-134, muscle; Zn-65, gut. Food seemed to be the primary source of all isotopes to fish. Ratios of isotope concentrations in fish to those in water were higher for both fathead minnow and lake trout than ratios reported from laboratory studies using aqueous exposures. Concentration ratios for Cs-134 in both fathead minnow and lake trout from oligotrophic Lake 224 were over an order of magnitude greater than published data for fish from eutrophic lakes.

Can J Fisheries Aquat Sci, 1986

Page 1. Response of Radioactive Trace Metals to Acid - Base Titrations in Contro ed Experimental ... more Page 1. Response of Radioactive Trace Metals to Acid - Base Titrations in Contro ed Experimental Ecosystems: Evaluation of Transport Parameters for Application to Whole-Lake Radiotracer ~xperiments&#x27; Peter H. SantschiF2 ...

Canadian Journal of Fisheries and Aquatic Sciences, 2001

Can J Fisheries Aquat Sci, 1980

Journal of Hydrology, Sep 1, 2003

This brief paper indicates that forest fires may have short and longer term effects on runoff and... more This brief paper indicates that forest fires may have short and longer term effects on runoff and thus, can influence trend studies on the response of watersheds to climate change. Twenty-two watersheds at the Experimental Lakes Area in northwestern Ontario were studied to view the impacts of climatic variability and forest fires on runoff. A roughly 30 year database demonstrated few trends in climatological variables and even fewer trends in runoff data at the 5% significance level. Daily maximum temperature increased by 0.053 °C per year, while precipitation in the months of February and March showed significant decreases. Total snow showed a significant decrease over a 30 year period at the 8% significance level. The Mann Kendall test for trend was applied to the runoff indices of 19 watersheds and it was revealed that only six exhibited trends. Of these, five had been burned during the test period. Virtually all burned watersheds showed initial increases in runoff, however, long term runoff trended lower in the burned watersheds, while the one watershed that was not burned showed an increasing trend. Forest fires alter the age distribution of trees with subsequent impacts on water yields in the short and longer term.

Environmental Science, 2005

We used a dynamic model to estimate the net carbon dioxide production (NCP) of three experimental... more We used a dynamic model to estimate the net carbon dioxide production (NCP) of three experimentally flooded upland areas (FLUDEX) over a period of 4 years and NCP from a flooded wetland (ELARP) over 12 years (2 year pre-flooding, 10 years post-flooding). The 3 flooded upland areas had been chosen to have differing amounts of carbon stored in soils and

Radionuclides in the Study of Marine Processes, 1991

Environmental Science, 2005

Limnology and Oceanography, 1991

The algal taxonomy and community metabolism of epilithon and epiphyton in a lake experi- mentally... more The algal taxonomy and community metabolism of epilithon and epiphyton in a lake experi- mentally acidified to pH 5 were compared with those in a nearby neutral lake to interpret the effect of acidification on periphyton. Acidification altered the algal community structure. Acidified pe- riphyton had fewer filamentous cyanobacteria, whereas green algae (especially Mougeotia) were relatively more abundant. Periphytic metabolism

Water, Air, & Soil Pollution, 1995

The relationship between mercury (Hg) concentrations in freshwater biota and trophic position, as... more The relationship between mercury (Hg) concentrations in freshwater biota and trophic position, as defined by stable nitrogen isotope ratios (d15N), was examined in 6 lakes in northwestern Ontario. The heavier isotope of nitrogen (15N) increases an average of 3 parts per thousand (‰) from prey to predator and is used as a measure of an organism&amp;#39;s trophic position. Dorsal muscle