Arthur S. Brooks

Selenium uptake and transfer in an aquatic food chain and its effects on fathead minnow larvae

The transfer of Se (Na2SeO4) was followed through a laboratory food chain (wateralgae-rotifer-larval fish) and its effect on larval fathead minnows (Pimephales promelas). Selenium transfer between algae (Chlorella pyrenoidosa) and rotifers (Brachionus calyciflorus) was a function of time and food availability. Selenium concentrations in the rotifers ranged from 46 to 91Μg Se · g−1 dry weight after 5 hr of feeding. Selenium concentrations (±SD) in larval fish reached 61.1±1.1 Μg Se · g−1 dry weight for 9 day-old larvae and 51.7+1.6 Μg Se · g−1 for 17 day-old larvae after 7 and 9 days of feeding with Se-contaminated rotifers, respectively. Final dry weights of larvae fed Se-contaminated rotifers were significantly lower than those of controls, although acute toxicity (mortality) was not demonstrated. The biological halflife of food-derived Se in the larvae was 28 days.

Kinetics of accumulation of selenium from food and water by fathead minnows

Abstract Relationships between Se concentration in water and/or food and the kinetics of uptake, accumulation and depuration of Se in fathead minnows ( Pimephales promelas Rafinesque) were determined by use of repeated measurements of Se radiotracer activity in live fish. Groups of 10 fish each were maintained in separate aquaria and were continuously exposed to 10, 20 or 40 ng Se ml −1 as Na 2 SeO 4 (selenate) and/or daily offered 157, 314 or 628 ng Se via Daphnia which had ingested Se-laden Chlamydomonas . Within 4 weeks the fish exposed to Se in the water reached an equilibrium body burden of Se at a concentration 25.3 times that in the water. Fish exposed to Se in the food had not reached an equilibrium after 11 weeks, but equilibrium concentrations were calculated to be 0.3 times that in the food according to a kinetic model. The accumulation in fish of Se from both water and food was additive. The rates of depuration suggested the existence of two functional compartments of Se in the fish that could represent different Se compounds.

Selenium compounds in the fathead minnow (Pimephales promelas)—I. Uptake, distribution, and elimination of orally administered selenate, selenite and l-selenomethionine ☆ ☆☆

Treatment of fathead minnows (Pimephales promelas) with either [75Se]selenate, -selenite or -l-selenomethionine by gavage at 20 ng Se/g resulted in organ uptake and early distribution patterns which differed significantly between compounds. The greatest differences in uptake between compounds was observed in liver tissue which accumulated much less [75Se]selenate than either selenite or l-selenomethionine. The 75Se burdens and relative distribution among the various organs were nearly identical during the elimination phase for [75Se]selenate and -selenite. This suggests that selenium derived from these compounds converge to a common metabolic pool. The whole body T1/2, rate of 75Se uptake and magnitude of 75Se accumulation were generally greater for [75Se]selenomethionine than the inorganic forms. Selenium-75 was present in the bile following the oral administration of each compound. The partitioning of selenate and selenite into the plasma and cellular fraction of blood differs with both the compound and time following exposure.

Analysis of Thermal Features of Lake Michigan from AVHRR Satellite Images

The seasonal dynamics of thermal features in Lake Michigan were studied using numerous sea surface temperature images acquired from the NOAA Advanced Very High Resolution Radiometer from May–December, 1990. In southern Lake Michigan, the vernal thermal front moved offshore and to the north between 7 May 1990 and 11 June 1990. Inshore of the front, surface temperatures were > 10.0°C while offshore surface temperatures remained < 4.5°C. In northern Lake Michigan, thermal fronts were not prevalent until late June. Southern Green Bay consistently contained the warmest water in Lake Michigan and exceeded 15.0°C in May. Warm bay-water frequently mixed with cooler lake-water through the channels at the north end of the bay. Warm water plumes remained intact for several days with S/SW winds but were quickly obliterated by a N/NE wind. Upwelling was most conspicuous along the eastern shore of the lake. Depending on wind direction, upwelled water formed broad continuous nearshore bands or isolated patches of relatively cold water. Evidence of upwelling 1–3 days after the instigating wind event suggested oscillations of internal waves. Our study shows that the frequent acquisition of satellite images is useful to describe significant thermal features in a large lake.

Effects of Free and Combined Chlorine and Exposure Duration on Rainbow Trout, Channel Catfish, and Emerald Shiners

Abstract Laboratory bioassays to determine the acute toxicity of monochloramine, dichloramine, hypochlorous acid, and hypochlorite ion to emerald shiners Notropis atherinoides, channel catfish lctalurus punctatus, and rainbow trout Salmo gairdneri were conducted. Four exposure regimes typical of chlorination schedules at operating steam electric power plants were used. Fish were exposed for single 15-minute, 30-minute, 120-minute, and 4 × 30-minute periods. Based on median lethal concentrations (LC50s), the nominal solution of hypochlorous acid was the most toxic, followed closely by the solution dominated by dichloramine; nominal monochloramine and hypochlorite ion solutions had a third to a quarter the toxicity of the other two. On the average, emerald shiners were 1.8 times more sensitive than channel catfish and 3.3 times more sensitive than rainbow trout to the four forms of chlorine. The fish were most tolerant of chlorine during short-duration exposures and least tolerant during the continuous 120-...

The Potential Influence of Climate Change on Offshore Primary Production in Lake Michigan

This paper examines the potential influence of climate change on the primary productivity of Lake Michigan. Two general circulation models (GCMs) provided physical information on projected regional climate for the years 2030, 2050, and 2090. A 30-year record of meteorological data and limnological observations, from 1961 to through1990, was used to define present, baseline conditions for the lake. GCM output was used to develop scenarios of future thermal characteristics, mixing patterns, and surface irradiance, which were then used to drive primary production calculations. Mean annual primary production for the base period was 116 g C/m2. Under base conditions thermal stratification of the lake occurred on 13 June and extended 135 days until 26 October. Conditions projected for 2090 showed the mean date of stratification beginning as early as 5 April and remaining for 225 days until 20 November. Estimated mean annual primary production under these conditions totaled 113 g C/m2, a decrease of 3% from the mean base value. Under the most extreme conditions of maximum projected cloud cover for 2090, primary production in that year could fall to 101 g C/m2, a decrease of 13% from the base mean, or down 22% from maximum base production calculated under minimum base cloud cover conditions. The projected decrease may be attributed to physical/chemical constraints imposed on spring primary production by altered climate conditions. Early stratification would shorten the period of winter-spring mixing, during which time nutrients from the sediment are transported to the productive euphotic zone. The spring bloom was projected to diminish if early stratification capped the nutrient supply, and increased cloud cover reduced light input for photosynthesis. To a lesser extent fall production could also be reduced by the extension of the stratified period. Altered physical/chemical conditions influenced by a changing climate will be an important factor to consider in assessing future water quality conditions, primary production and the food web dynamics of the Great Lakes.

The Effects of Intermittent Chlorination on Rainbow Trout and Yellow Perch

Abstract Rainbow trout, Salmo gairdneri, and yellow perch, Perca flavescens, were exposed to residual chlorine for single 30-minute and triple 5-minute doses. Tests were conducted at 10, 15, and 20 C with both species plus 25 and 30 C for the perch. Single exposure 30-minute LC50 values for the perch ranged from 0.70 mg/liter at 30 C to 8.0 mg/liter at 10 C. Triple 5-minute exposure LC50 values for the perch were 22.6 and 9.0 mg/liter at 10 and 20 C, respectively. Rainbow trout 30-minute LC50 values were 0.99 and 0.94 mg/liter at 10 and 15 C, respectively. Two groups of trout tested at 20 C yielded 30-minute LC50 values of 0.60 and 0.43 mg/liter. Triple exposure 5-minute LC50 values for the trout were 2.87 mg/liter at 10 C and 1.65 mg/liter at 20 C. Mortality occurred immediately after exposure to chlorine in the 30-minute perch tests at 10 and 15 C, but was delayed 2–12 hours at the higher temperatures. This pattern was reversed in the 5-minute triple exposure tests. Rainbow trout exhibited rapid mortali...

Excretion of total phosphorus, dissolved reactive phosphorus, ammonia, and urea by Lake MichiganMysis relicta

Rates of nutrient release byMysis relicta in Lake Michigan were measured on five nights at a 45-m station near Milwaukee, Wisconsin, U.S.A., in the summer of 1977. Nocturnal vertical migrations of the mysids were monitored with both echosounder tracings and vertical net tows. Estimates of the total areal dry mass of the mysids ranged from 600 to 1 820 mg m−2. Rates of release of dissolved reactive phosphorus, total phosphorus, ammonia, and urea were measured in dark incubations on shipboard. Excretion experiments were initiated immediately after mysids were collected from each of several vertical net hauls. The depths of maximum mysid densities corresponded approximately with a deep phytoplankton peak located in the vicinity of the thermocline. Semiquantitative ‘demands’ for N and P by phytoplankton within this peak were obtained from14C estimates of primary production from a previous study, assuming a constant C:N:P ratio for the algae. These algal nutrient ‘demands’ were compared to potential N and P release by the mysids to obtain a first approximation of the relative rates of nutrient supply and demand for the field phytoplankton populations. Our analysis indicates that mysids may directly supply about 1–10% of the daily N and P ‘demands’ of the phytoplankton in the deep peak. However, indirect interactions betweenMysis relicta and other organisms, such as small zooplankton and fishes, could be major factors in nutrient recycling within the metalimnion and subthermocline region of Lake Michigan.

The effect of selenium in water and food on Daphnia populations.

Populations ofDaphnia magna exposed to selenium as Na2SeO4 in water over a range of 0–1.0 mg Se/L and fed control algae showed decreased survival, reduced numbers of offspring, and a lower intrinsic growth rate (“r”) in a concentration-response manner.Daphnia fed algae grown in medium containing selenium when exposed to selenium in the water exhibited a reduced response with respect to these variables over the same concentration range. The uptake of75selenium from water was significantly reduced when theDaphnia were fed selenium-laden algae or when DL-selenomethionine was present in the water. The presence of organically bound selenium in the food or water appears to alter the rate of incorporation of inorganic selenium and reduces the toxic effects onDaphnia populations.

The Effects of Monochloramine on Selected Riverine Fishes

Abstract Ten riverine fish species were tested at 10, 20, and 30 C to determine their resistance to monochloramine. The exposure regime consisted of four 40-minute exposures administered at 5-hour intervals over 24 hours. All species exhibited an inverse relationship between temperature and median lethal (LC50) concentrations. LC50 values generally decreased by a factor of two as the exposure temperature increased from 10 to 30 C. LC50 values ranged from 0.35 mg/liter at 30 C for the emerald shiner to 3.00 mg/liter at 10 C for the bluegill. Based on their resistance to monchloramine at 30 C the fish were separated into sensitive and resistant groups. The sensitive group, which included (in decreasing order of sensitivity) the emerald shiner (Notropis atherinoides), spotfin shiner (Notropis spilopterus), common shiner (Notropis cornutus), channel catfish (Ictalurus punctatus), white sucker (Catastomus commersoni), and sauger (Stizostedion canadense), had LC50 values ranging from 0.35 to 0.71 mg/liter. The ...