GLERL Publications Abstracts: FY 1987

ASSEL, R.A. Great Lakes ice cover and ice cycles - a brief review. Annual meeting of the American Association for Advancement of Science, Chicago, IL, February 14-18, 1987. 5 (1987).

The Laurentian Great Lakes are one of the major natural resources of North America. One important physical feature of the lakes is the annual ice cover that forms on all or portions of each of the lakes during winter. The ice cover has a major impact on the economy by impeding and eventually stopping commercial navigation, interfering with hydropower production and damaging shore structures. Four aspects of ice on the Great Lakes are briefly discussed in this paper: (1) ice formation processes and ice cover, (2) ice cover thickness, (3) seasonal progression of ice cover extent, and (4) problems associated with ice cover on the Great Lakes.

ASSEL, R.A. Technical Note: Thermal changes in Lake Superior storage in 1976. Journal of Hydraulic Engineering 113(9):1175-1181 (1987).

Thermal change in lake storage between beginning-of-month (BOM) dates was calculated from joint volumetric and mass balances. Thermal change in storage was important in May and July because published data (5) indicate no change in lake storage during these months in 1976. For the remaining months, thermal change in storage peaked during the period of thermal stratification, when it accounted for over 10% of the change in storage. Thermal corrections to net basin supply (NBS) ranged from 30%, to more than 100% when the NBS was less than 400 m3/s; thermal corrections to NBS when greater than 4003/s were between 1% and 30%, and they averaged 8.5%. An error analysis indicated that a 0.4%o C error along the entire BOM temperature profile yielded an average error of 27% in the monthly thermal change in storage.

BENNETT, J.R. The physics of sediment transport and deposition. Hydrobiologia 149:5-12 (1987).

No abstract.

BENNETT, J.R., and A.H. CLITES. Accuracy of trajectory calculation in a finite-difference circulation model. Journal of Computational Physics 68(2):272-282 (1987).

The prediction of drifting object motion due to currents in an irregular body is a complex problem with a wide range of practical applications. Simple numerical methods for interpolating current velocity fields have spatial interpolation and time integration errors that result in misleading solutions. The method described in this paper minimizes these problems, yielding much more accurate predictions. This method can be easily implemented in other finite-difference models or finite-element models.

CAMPBELL, J.E., A.H. CLITES, and G.M. GREENE. Measurements of ice motion in Lake Erie using satellite-tracked drifter buoys. NOAA Data Report ERL GLERL-30, (PB87-186409/XAB) 28 pp. (1987).

No abstract.

Carney, H.J., and G.L. FAHNENSTIEL. Quantification of track and grain density autoradiography and evaluation of 14C loss on preservation. Journal of Plankton Research 9(1):41-50 (1987).

Sources of error in quantifying autoradiography were determined with unialgal cultures and natural assemblages. Carbon-14 activity of cells as recorded by track autoradiography was generally not significantly different from scintillation counts. Differences which did occur were apparently due largely to filter-retained extracellular 14C. An analysis of 37 preparations confirmed that tracks per cell for healthy log-phase populations followed a Poisson distribution. Quantification and analysis of intraspecific distributions for the grain density technique were relatively difficult. 14C loss on preservation was lower and more consistent (0-21%) than previously reported. Autoradiographs indicated that this loss consisted of unfixed filter-retained 14C or an extracellular release product rather than carbon within algal cells. Thus, track autoradiography was more reliable for quantifying species-specific net productivity than other studies have indicated.

CROLEY, T.E.II. Minimizing long-term wind set-up errors in estimated mean Erie and Superior Lake levels. NOAA Technical Memorandum ERL GLERL-64, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB87-217253/XAB) 40 pp. (1987).

Errors in computed mean lake levels, caused by wind set-up, are estimated from linearized hydrodynamic shallow-water equations applied to Lakes Erie and Superior for 'historical and current gage networks. Observations of maximum unit error (that results from a unit wind stress) with each of the historical networks and with the current network are consistent with lake orientation and network placement considerations. Optimum network gage selections are made from the 16 available Lake Erie gages to minimize mean square set-up error estimated over one season's wind data, mean square total error estimated from daily data for 12 years, and mean square total error with constraints on the network size. Optimum network gage selections for Lake Superior are made from the 10 available gages to minimize mean square total error estimated from 12 years of daily data with and without constraints on the network size. It is not possible to eliminate wind set-up errors in mean lake levels if Thiessen weights must be used (although errors can be kept quite small); without this constraint, wind set-up errors can be eliminated from mean lake level computations. This allows selection of the weights that minimize other types of errors. The differences in net basin supply and lake volume computations that result by using optimum weights instead of Thiessen weights appear significant on both Lakes Erie and Superior.

CROLEY, T.E.II. The Great Lakes large basin runoff model. Proceedings, Engineering Hydrology Symposium, Williamsburg, VA, August 3-7, 1987. Hydrology Division, American Society of Civil Engineers, New York, NY, 14-19 (1987).

No abstract.

CROLEY, T.E.II. Water level fluctuations on the Great Lakes. In The Great Lake Erie, A Reference Text for Educators and Communicators, R.W. Fortner and V.J. Mayer (eds.). The Ohio State University Research Foundation, Columbus, OH, 93-102 (1987).

No abstract.

CROLEY, T.E.II. Wind set-up error in mean lake levels. Journal of Hydrology 92:223-243 (1987).

Lake surfaces tilt under steady wind set-up; downwind water-level gage readings increase while upwind gage readings decrease. This gives an error in the mean (spatial average) gage readings with consequent error in lake volume estimates that are based on the mean lake level. This error may be minimized or even eliminated by judicious selection of gage locations and weights for averaging. The wind set-up errors in computed mean lake levels are estimated from linearized hydrodynamic shallow-water equations applied to Lake Erie for historical and current gage networks. Observations of maximum unit error (that results from a unit wind stress) with each of the historical networks and with the current network are consistent with lake orientation and network placement considerations. Optimum network gage selections are made from the sixteen available Lake Erie gages to minimize the mean square set-up error estimated over one season's wind data, the mean square total error estimated from daily data for twelve years, and the mean square total error with constraints on the network size. It is not possible to eliminate wind set-up errors in mean lake levels with the constraint that Thiessen weights be used (although errors can be kept quite small). Without this constraint, however, wind set-up errors can be eliminated from mean lake-level computations. This allows selection of weights that minimize other types of errors.

CROLEY, T.E., II, and H.C. HARTMANN. Near-real-time forecasting of large-lake water supplies: A user's manual. NOAA Technical Memorandum ERL GLERL-61, (PB87-178026/XAB) 82 pp. (1987).

The Great Lakes Environmental Research Laboratory developed a semiautomatic software package for making deterministic or probabilistic outlooks of basin moisture storage conditions, basin runoff, net lake supplies, and lake levels six full months into the future for large lakes. We designed the package especially for use on small computers with a standard FORTRAN-77 or TURBO-PASCAL compiler, 2-5 Megabytes of disk storage, and a minimum of CPU and memory resources. The package combines our Large Basin Runoff Model applications on each of the subbasins about a lake to represent the entire basin. Our near-real-time data reduction system uses new algorithms to efficiently determine daily areal averages of meteorologic variables over each of the subbasins. The model and data reduction system are combined into a useful, easy-to-use, semiautomatic package that consists of easily supported modules for making near real-time forecasts of basin runoff and lake levels. Although the package was developed for use on the Laurentian Great Lakes, we currently use it on Lakes Superior and Champlain and can apply it in little more than the time it takes to receive climatologic records for an area. The modules' construction is presented in some detail; the use of these modules and their component computer programs also are detailed herein with the Lake Superior Basin used as an example.

DERECKI, J.A., and F.H. QUINN. Record St. Clair River ice jam of 1984. Journal of Hydraulic Engineering 112(12):1182-1194 (1986).

The record St. Clair River ice jam of April 1984 produced major impacts on the levels and flows of the Great Lakes, and on navigation throughout the system. Following the onset of the jam, Lake St. Clair water levels dropped about 0.6 m as the inflow was decreased by the jam. At the peak of the jam the flows were reduced by approximately 65%. The jam had a duration of 24 days. Following the jam breaking on April 29, 1984, the waters of Lake St. Clair rose rapidly, recovering approximately 75% of the drop in levels in four days. Computer simulations indicate that it will take about a year for most and at least 3 years for all the excess water stored in Lakes Michigan and Huron during the jam to be dissipated and for levels in those lakes (and Lakes St. Clair and Eire, downstream) to return to prejam conditions.

DERECKI, J.A., and F.H. QUINN. Use of current meters for continuous measurement of flows in large rivers. Water Resources Research 23(9):1751-1756 (1987).

Flows in the unregulated Great Lakes connecting channels, the St. Clair and Detroit Rivers, are normally determined using mathematical flow models with calibration based on periodic discharge measurements taken during the open-water seasons. Consequently, the calculated flows normally exhibit good accuracy during ice-free periods, but may contain large errors during winter months with extensive ice cover. The St. Clair River is particularly prone to large ice jams because of practically unlimited ice flow supply provided by Lake Huron and an extensive river delta that retards the passage of these ice flows. This study describes the experimental results of continuous flow measurements using electromagnetic (EM) current meters and an acoustic Doppler current profiler (ADCP) meter during the 1983-1985 period. A record ice jam in the St. Clair River occurred in April 1984 and provided an excellent opportunity for testing the current meter program. Verification of current meter results was provided by flows transferred from the Detroit River, which was ice-free and permitted accurate flow simulation. The current meter flow measurement program illustrated high consistency of exponential (logarithmic) vertical distribution of velocities. Results indicate that accurate estimates of mean river flows can be obtained with a single well-placed current meter. However, the EM current meters are direct contact single-point sensors that are affected by frazil ice during winter and weed effects during most of the year. The ADCP meter is a remote sensor of velocities in the overhead water column and is not affected by the frazil ice and weed problems.

EADIE, B.J., and J.A. ROBBINS. The role of particulate matter in the movement of contaminants in the Great Lakes. Advances in Chemistry Series No. 216, Sources and Fates of Aquatic Pollutants :319-364 (1987).

Particle-contaminant interactions and subsequent behavior of the particulate matter control the long-term concentration of many compounds in aquatic systems. Even in deep systems such as the Great Lakes, particle settling times from the water column are less than 1 year. After reaching the bottom, contaminant-laden particles are redistributed by episodic cycles of resuspension and redeposition, resulting in focusing, which is the spatially in homogeneous distribution of contaminants in sediments. Bioturbation, coupled with focusing, provides source material to the resuspendible pool. The combination of these processes mediates both the composition and long-term behavior of contaminants in these lakes.

FAHNENSTIEL, G.L., and D. SCAVIA. Dynamics of Lake Michigan phytoplankton: Primary production and growth. Canadian Journal of Fisheries and Aquatic Sciences 44(3):499-508 (1987).

Primary production was measured with the 14C technique during May and July-August 1982-84. 14C experiments varied from short-term incubations (1-2 h) in a photosynthesis - irradiance (P-I) chamber to 24-h in situ incubations. The maximum assimilation number from six P-I experiments during thermal stratification averaged which agreed well with estimates from the 1970s. Chlorophyll-corrected P-I curves were combined with incident irradiation, chlorophyll concentrations, and extinction coefficients to estimate daily production (model estimate). Summer average integral production estimates in 1983 and 1984 were 615-630 . Approximately 50% of summer primary production occurred below the epilimnion. Daily model production estimates were higher than 24-h in situ estimates at light intensities above lk, the light saturation parameter, and similar at intensities below lk. Comparisons of production estimates converted to growth rates suggest that 24-h in situ estimates provide a measure close to net production whereas model estimates provide a measure greater than net production. Summer epilimnetic growth rate estimates were low (range ), reflecting the limited availability of phosphorus.

FAHNENSTIEL, G.L., and D. SCAVIA. Dynamics of Lake Michigan phytoplankton: Recent changes in surface and deep communities. Canadian Journal of Fisheries and Aquatic Sciences 44(3):509-514 (1987).

Lake Michigan phytoplankton dynamics were studied from the end of spring isothermal mixing (May) through midstratification (July-August) in 1982-84. Phytoplankton composition shifted from a diatom-dominated community (75% of phytoplankton carbon) during May to a phytoflagellate-dominated community (71% of phytoplankton carbon) during July-August. This summer phytoflagellate dominance in the 1980x is distinctly different from the summer blue-green and green algae dominance in the 1970s. Food web interactions caused by a changing zooplankton composition and nutrient supply changes were two possible causes. A deep chlorophyll layer (DCL) developed after the onset of thermal stratification. The DCL initially developed in the 15-30 m region and deepened to 25-50 m in July and the 40-70 m region in August. The DCL in 1982-84 was larger in size and located deeper in the water column than those reported from the 1970s. This difference was related to increases in light transparency found in the 1980s that were a result of increased zooplankton grazing pressure.

FONTAINE, T.D., III, and B.M. Lesht. Contaminant management strategies for the Great Lakes: Optimal solutions under uncertain conditions. Journal of Great Lakes Research 13(2):178-192 (1987).

Optimization, uncertainty analysis, and mass balance modeling techniques were combined into a framework that can help decision makers identify cost-effective load reduction methods for achieving acceptable contaminant concentrations in the Great Lakes. The utility of the framework is demonstrated by deriving an optimal phosphorus load reduction plan for the Great Lakes. An optimal plan is defined as the least-cost approach that can achieve desired phosphorus concentrations in all Great Lakes basins under realistic, stochastic phosphorus loading and settling rates. The analysis suggests that implementation of phosphorus load reduction measures recommended in the U. S. - Canadian 1978 Great Lakes Water Quality Agreement, its 1983 supplement, and other plans that do not account for environmental uncertainty may by sub-optimal. Compared with the load reduction strategies of the 1978 Water Quality Agreement and its supplement, implementation of the optimized load reduction strategy would lead to substantial annual cost savings and an increased probability of achieving desired phosphorus concentrations. Results emphasize the importance of quantitatively accounting for environmental uncertainty in management models.

FONTAINE, T.D., III, and B.M. Lesht. Improving the effectiveness of environmental management decisions with optimization and uncertainty analysis techniques. In Systems Analysis in Water Quality Management, M.B. Beck (ed.). Pergamon Press, New York, 31-39 (1987).

The stochastic nature of environmental processes and forcing functions diminishes the credibility of management decisions that are based on models that employ "average" conditions. Our thesis is that the environmental decision-making process must quantitatively account for environmental uncertainties. In doing so, management strategies can be formulated that are based on acceptable levels of risk to the environment. We have extended this uncertainty analysis approach to include a linear programming optimization algorithm in order to demonstrate that acceptable risk scenarios can be devised which are cost effective as well. We demonstrate this point for the Great Lakes by showing that present and proposed phosphorus management plans have neither the probability of success nor the cost effectiveness of a management plan that is based on a combined uncertainty-optimization analysis. Present and proposed phosphorus management plans are predicted to have at most a 55% overall probability of meeting Great Lakes phosphorus goals. The combined uncertainty-optimization approach points to management options whose overall probability of success in meeting Great Lakes phosphorus goals varies between 55% and 99%. The costs associated with these options also vary but savings as great as 400 million dollars per year could be realized with no diminution in goal achievement when compared to present and proposed management plans.

HARTMANN, H.C. An evaluation of Great Lakes hydraulic routing models. NOAA Technical Memorandum ERL GLERL-66, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB88-122700/XAB) 9 pp. (1987).

Water resource studies require hydraulic routing models for simulating water levels of the non-regulated Great Lakes. This report compares the U.S. Army Corps of Engineer's hydraulic routing model and the Great Lakes Environmental Research Laboratory's Hydrologic Response Model (HRM). Although the model solution techniques produce equivalent results, the HRM reduces cpu requirements by 94%. The HRM also uses discharge equations that better reflect present channel conditions and a more appropriate conversion of lake storage changes to lake level fluctuations.

HARTMANN, H.C., and T.E. CROLEY. Probabilistic forecasts of continued high Great Lakes water levels. Engineering Hydrology Symposium, Williamsburg, VA, August 3-7, 1987. Hydrology Division, American Society of Civil Engineers, 20-25 (1987).

Existing projections of Great Lakes water levels over the next several years do not consider how meteorologic variability affects the hydrologic processes (basin runoff, overlake precipitation, lake evaporation) that control lake levels. We can make such considerations with conceptual model-based techniques developed by the Great Lakes Environmental Research Laboratory (GLERL) for the system-wide simulation of Great Lakes water supplies, connecting channel flows, and lake levels. The package incorporates GLERL's large Basin Runoff Model (LBRM), which is an interdependent tank-cascade model that employs analytical solutions of climatic considerations relevant for large watersheds. We use meteorologic sequences of daily precipitation and maximum and minimum air temperatures with the runoff model to simulate basin moisture conditions and runoff, and then with empirical estimators of overlake precipitation and lake evaporation to simulate water supplies to each of the Great Lakes. Finally, we use the operational regulation plan for Lake Superior to simulate monthly lake levels and flows through the connecting channels; the regulation plan includes a hydraulic routing model that considers diversions and obstruction of connecting channel flows due to ice jams. The integrated models form a package which enables probabilistic assessments of diversions, regulation plans, or climatic change that reflect the natural long-term variability of the Great Lakes system. The models use meteorologic scenarios based on historical records to determine probabilities of future Great Lakes levels.

LANDRUM, P.F., J.P. Giesy, J.T. Oris, and P.M. Allred. Photoinduced toxicity of polycyclic aromatic hydrocarbons to aquatic organisms. In Oil in Freshwater: Chemistry, Biology, Countermeasure Technology, J.H. Vandermeulen and S.E. Hrudey (eds.). Pergamon Press, New York, 304-318 (1987).

Polycyclic aromatic hydrocarbons (PAH) such as anthracene are ubiquitous pollutants that are normally not considered acutely toxic to aquatic organisms because they are only sparingly soluble in water. Thus, bioassays conducted under the usual laboratory conditions have resulted in estimates of acute toxicity that exceed the aqueous solubilities of PAH. However, these studies are usually conducted under conditions that minimize photodegradation, and therefore the potential to observe ecologically relevant photoinduced toxicity is eliminated. Studies under more ecologically relevant conditions in an illuminated artificial stream microcosm have demonstrated that anthracene is acutely toxic (100% mortality) to juvenile bluegill sunfish at 12 mg x 1-1 in less than 9 h. This toxicity is more than 400 times greater than previously reported no-effect concentrations. Daphnia pulex are even more sensitive (LT50, time to 50% immobilization - 13 min at 1.2 mg x 1-1). These dramatic effects occur as a result of the interaction of bioaccumulated parent PAH and light, not the action of externally formed photodegradation products. Preliminary screening has indicated that benzo(a)pyrene is even more toxic than anthracene. We predict that 50% of the aquatic organisms in a lake will be immobilized at a depth of 7.25 m with a 1.2 mg x 1-1 anthracene concentration based on the use of the Bunsen-Roscoe Law of Reciprocity, the measured extinction coefficient for UV-B in Lake Michigan (0.575 m-1), an average summer day length of 14 h, and the LT50 for Daphnia pulex. These effects, the depths at which they may be occurring, and the concentrations of PAH in the Great Lakes indicate that acute effects could be occurring at present in the Lakes. With expected increases of PAH load due to increased coal usage and increased ambient levels of solar UV due to depletion of the ozone layer, the potential exists for large effects in the Great Lakes and other aquatic systems.

LANDRUM, P.F., S.R. Nihart, B.J. EADIE, and L.R. HERCHE. Reduction in bioavailability of organic contaminants to the amphipod Pontoporeia hoyi by dissolved organic matter of sediment interstital waters. Environmental Toxicology and Chemistry 6:11-20 (1987).

Dissolved organic matter (DOM) in aquatic systems is known to reduce the bioavailability of heavy metals. Recent studies have shown similar reductions in bioavailability of organic contaminants. The mechanism for reduction, with Aldrich humics, was to reduce the freely dissolved, bioavailable, xenobiotic concentration by partitioning to DOM. This mechanism was also found to apply to organic contaminants in the presence of DOM from interstitial waters. A reverse-phase separation technique was used to measure the sorbed xenobiotic, and by difference from the total, the freely dissolved concentration of a contaminant permitting the calculation of a partition coefficient (Krp). Equilibrium partitioning of selected polycyclic aromatic hydrocarbon and polychlorinated biphenyl congeners to the DOM, in interstitial waters from several geographical sources, ranged over several orders of magnitude for a single compound. The reduction in bioavailability was measured by reduction in the conditional uptake rate constant for organic xenobiotics in the presence of DOM, for the amphipod Pontoporeia hoyi (the major benthic invertebrate in the Great Lakes). Reduction in the conditional uptake rate constant versus controls was used to calculate a biologically determined partition coefficient (Kb). The log Krp was well correlated with log Kb, log Kb = 1.54(0.15) + 0.723(0.03) log Krp (r2 = 0.74, n = 195) over a range of three orders of magnitude in measured partition coefficient for individual compounds using DOM from different sources.

LANG, G.A., and M.A. QUIGLEY. A method for using a CalComp Digitizer coupled with menu-driven software to measure amphipod body length and gut fullness. NOAA Technical Memorandum ERL GLERL-62, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB87-186920/XAB) 18 pp. (1987).

A method for measuring amphipod body length and gut fullness, using a CalComp 9480 digitizer coupled with interactive, menu-driven software, is described. In addition to having a high degree of precision and accuracy, the digitizer method constitutes a rapid and efficient route for transferring raw length data from the microscope to an on-line data file. Procedure for use of the FORTRAN-77 software program CRITTER is fully detailed and a complete listing of the program is supplied.

LESHKEVICH, G.A. A field calibration technique for airborne ice reflectance measurment. Proceedings, U.S. Army Corps of Engineers Fifth Remote Sensing Symposium, Volume I, Remote Sensing Applications for Water Resources Management, Ann Arbor, MI, October 28-30, 1985. 70-77 (1986).

A technique is described for the calibration of, and correction for possible atmospheric effects on, airborne spectral reflectance measurements of now and freshwater ice surfaces from relatively low altitudes, using data collected in the field. Radiance measurements in the visible and near-infrared (400-1100 nm) range were made of old snow, open water, and four ice types using a programmable band radiometer from an altitude of 300 m under clear skies. Irradiance measurements were made at the surface before and between airborne radiance measurements using a barium sulfate reference panel. The spectral reflectance factors for snow and open water at the surface together with their airborne radiance (signal) values are used to derive values for attenuation and path radiance which are used to correct the airborne ice reflectance measurements. Reflectance factors corrected using the technique are compared to values uncorrected for atmospheric attenuation and path radiance. Results show a slight average increase in reflectance of the corrected data.

Lesht, B.M., and N. HAWLEY. Near-bottom currents and suspended sediment concentration in southeastern Lake Michigan. Journal of Great Lakes Research 13(3):375-386 (1987).

In a study of sediment transport at the edge of the coastal shelf (28 m depth) in southeastern Lake Michigan we used an instrumented tripod to make continuous observations of horizontal current velocity, temperature, and turbidity within 1 meter of the bottom for 4 weeks during October 1981. The concentration of total suspended material (TSM) 0.9 m above the bottom varied from 1 to 5 mg/L in response to coastal up welling, surface waves, and currents that exceeded 0.28 rn/s (0.7 m above the bottom) on occasion. Advection of the Grand River plume also contributed significantly to the variations in the observed TSM concentration. Currents near the bottom were well correlated with surface winds and, although upwelling currents transported sediment upsiope, the net horizontal sediment flux during the period of observation was west-south westward, almost directly offshore. The magnitude of the horizontal sediment flux was approximately 1,000 times the magnitude of the vertical flux estimated from sediment traps deployed as part of earlier studies. We infer that local resuspension occurred roughly 20 percent of the time and the critical mean flow speed (at 0.7 m) for resuspension of the local silty sands was estimated to be about 0.18 m/s.

LIU, P.C. Assessing wind wave spectrum representations in a shallow lake. Ocean Engineering 14(1):39-50 (1987).

This paper presents an objective assessment of three published wave spectrum formulas for the shallow sea. It compares wave spectra estimated by these formulas with those calculated from actual field measurements made in Lake Erie during 1981 in depths ranging from 1.4 to 14.0 m. The results show that the models each have various degrees of effectiveness and applicability. The choice of which model to use may depend upon the availability of input parameters, and is still basically subjective. The models specifically developed for the shallow depth are found to be less effective. The form of spectral representation may remain similar at all depths, with depth affecting only the wave parameters that characterize the spectrum form.

LIU, P.C. Estimating long-term wave statistics from long-term wind statistics. Proceedings, 20th Coastal Engineering Conference, Coastal Engineering Research Council, Taipei, Taiwan, November 9-14, 1986. American Society of Civil Engineers, New York, 512-521 (1986).

The wave climate synthesis method, which derives long-term wave statistics from long-term wind statistics directly, is tested with four years of wind and wave measurements recorded from eight NOMAD buoys in the Great Lakes during 1981-1984. The results show that it is an excellent method for estimating long-term wave statistics and design wave height. While the method is by no means intended to replace wave hindcasting procedures, it is shown to be a useful additional tool for the coastal engineer.

LIU, P.C., and D.J. SCHWAB. A comparison of methods for estimating u* from given uz and air-sea temperature differences. Journal of Geophysical Research 92(C6):6488-6494 (1987).

This paper presents an objective assessment of four methods for estimating sea surface friction velocity u* from wind speed at height z, uz, and air-sea temperature difference. The methods are compared by using the computed friction velocity as the normalization factor in parametric correlations of wind-wave parameters with the wind and wave measurements made by NOMAD buoys in the Great Lakes. The results show that (1) wind profile parameters obtained from the four methods are generally comparable, (2) parametric correlations with parameters normalized by u* lead to significantly decreased percentage deviations over correlations normalized by uz, and (3) correlations based on u* derived from the four methods show nearly identical percentage deviations. The conclusions are that (1) u* normalization acts to eliminate the effect of atmospheric stability and (2) any of the four methods can be used effectively in practical applications.

Manny, B.A., G.L. FAHNENSTIEL, and W.S. GARDNER. Acid rain stimulation of Lake Michigan phytoplankton growth. Journal of Great Lakes Research 13(2):218-223 (1987).

Three laboratory experiments demonstrated that additions of rainwater to epilimnetic lake water collected in southeastern Lake Michigan stimulated chlorophyll a production more than did additions of reagent-grade water during incubation of 12 to 20 d. Chlorophyll a production did not begin until 3-5 d after the rain and lake water were mixed. The stimulation caused by additions of rain acidified to pH 3.0 was greater than that caused by additions of untreated rain (pH 4.0-4.5). Our results support the following hypotheses: (1) Acid rain stimulates the growth of phytoplankton in lake water; (2) phosphorus in rain appears to be the factor causing this stimulation. We conclude that acid rain may accelerate the growth of epilimnetic phytoplankton in Lake Michigan (and other similar lakes) during stratification when other sources of bioavailable phosphorus to the epilimnion are limited.

Matisoff, G., and J.A. ROBBINS. A model for biological mixing of sediments. Journal of Geological Education 35(3):144-149 (1987).

The post-depositional biological mixing of sediments can alter sedimentary structures and degrade the time resolution of dating techniques. Some organisms mix sediments in a random or diffusive manner, while others recycle or advect sediments by feeding at depth and defecating at the sediment surface. In addition, some organisms feed selectively on the sediment so that some particles are preferentially retained with the feeding zone, while others lag to the base of the zone. The generalized model presented here can be used to simulate the transient nature of these processes so that the student can observe the relative importance of time, depth distribution of mixing, feeding rates, sedimentation rates, decay rates, and other processes.

NALEPA, T.F. Long-term changes in the macrobenthos of southern Lake Michigan. Canadian Journal of Fisheries and Aquatic Sciences 44(3):515-524 (1987).

A benthic survey of 40 stations in southern Lake Michigan in 1980-81 was compared with results of studies conducted in the mid-1960's to evaluate long-term trends in populations. The tree major benthic groups, Pontoporeia, oligochaetes, and sphaeriids, were significantly more abundant in 1980-81. Compared with the most comprehensive survey (conducted in 1964-67), Pontoporeia increased two- to fivefold at depths less than 50 m, but did not increase at depths greater than 50 m. Oligochaetes increased two- to threefold regardless of sampling depth, while sphaeriids increased twofold at depths less than 50 m but decreased somewhat at depths greater than 50 m. Although oligochaete abundances increased, overall shifts in species composition were not apparent. Changes in abundances of Pontoporeia nay have been related to shifts in predation pressure from forage fish populations, but increased oligochaete abundances can likely be related to increased enrichment between the two sampling periods. Although apparent improvements in the water quality of Lake Michigan since the mid-1970's were not net reflected by benthic populations in 1980-81, continued monitoring of the benthos should provide a useful indicator of future trends.

NALEPA, T.F., and M.A. QUIGLEY. Distribution of photosynthetic pigments in nearshore sediments of Lake Michigan. Journal of Great Lakes Research 13(1):37-42 (1987).

To characterize nearshore detrital deposits and to identify potential input sources, photosynthetic pigments were examined in sediment cores taken from three stations in nearshore Lake Michigan between May and October 1979. Two stations were located at 11 m and one was at 23-m depth. At the 11-m stations, total pigment concentrations in the upper 0-1 cm layer were greatest in May and then declined, while seasonal changes at the 23-m station were not apparent. A high proportion of the spring influx of pigment oat the 11-m depth was undegraded, indicating freshly settled material from the water column as a likely source. Sediment chlorophyll concentrations in the spring were as high as 212 mg/g, but typical summer values were 1-7 mg/g. Although these pelagic inputs are temporary, strong links exist between this material and benthic invertebrate distributions.

NALEPA, T.F., C.C. Remsen, and J. Val Klump. Note: Observations of hydra from a submersible at two deepwater sites in Lake Superior. Journal of Great Lakes Research 13(1):84-87 (1987).

During a series of submersible dives at depths of 300 m and 400 m in southeastern Lake Superior, Hydra were observed attached to a variety of hard substrates including individual rocks, the edges of large boulders, and the undersurfaces of sandstone ledges. Although widespread, populations were generally found in distinct clumps. Based strictly on morphological features, the species resembled H. littoralis or H. carnea. The finding of Hydra at depths of 400 m in Lake Superior, the deepest sounding in the Great Lakes, would indicate that Hydra are not limited by depth.

SCAVIA, D., and G.L. FAHNENSTIEL. Dynamics of Lake Michigan phytoplankton: Mechanisms controlling epilimnetic communities. Journal of Great Lakes Research 13(2):103-120 (1987).

Lake Michigan epilimnetic algal and particulate organic carbon sedimentation rates, determined from moored and floating sediment traps, and algal loss rates due to crustacean zooplankton grazing, determined from manipulation experiments with natural assemblages, were estimated during 1983 and 1984 field seasons. Sedimentation was the most important algal loss in spring when colonial diatoms and calanoid copepods dominated the plankton. Grazing was the most important loss during summer when phytoflagellates and Daphnia spp. dominated. Comparisons between algal community production and loss due to sedimentation and grazing suggest that natural mortality may be significant, but it does not dominate control. An hypothesis is offered for overall control of phytoplankton dynamics in Lake Michigan.

SCAVIA, D., and G.A. LAIRD. Bacterioplankton in Lake Michigan: Dynamics, controls, and significance to carbon flux. Limnology and Oceanography 32(5):1017-1033 (1987).

Lake Michigan bacterial production, based on [3H-methyl]thymidine (TdR) incorporation and empirically determined conversion factors (5-25 x 109 cells nmol-1), decreased with distance from shore (~2x over 30 km), was higher at night (1.4x -.2.x), and decreased with depth (~10x over 100 m). TdR-based growth rates were consistent with independent antibiotic- and dilution-based estimates. Population size varied little and appeared controlled by balanced growth (0.02-0.33 h-1) and grazing (0.039-0.12 h-1). Growth correlated with temperature only below 10oC. Cell size ranged from 0.015 to 0.072 mm3. Carbon content averaged 0.154 +/- 0.047 pg C mm-3. Net annual carbon production was 142 g C m-2 yr-1. Summer averages were 28.9 (epilimnion), 10.4 (10-35 m), 1.6 (hypolimnion) mg C liter-1 d-1, and 652 mg C m-2 d-1 for the water column. Flux to microconsumers averaged 8.4 mg C liter-1 d-1 in the summer epilimnion. Annual areal bacterial carbon demand is met by autotrophic production only if little of the latter is lost by other means. This suggests that external loads are needed, our conversion factors are high, or autotrophic production is underestimated. Although only small adjustments of those factors will satisfy the annual balance, the summer imbalance is still too large. We suggest that temporal and spatial disequilibrium of labile organic carbon supply and bacterial use is responsible for the apparent discrepancy during summer.

SCHWAB, D.J. Great Lakes storm surge and seiche. Great Lakes Forecaster's Handbook, Section 10, September 14-18, 1987, NOAA National Ocean Service, 10 pp. (1987).

No abstract.

SCHWAB, D.J. Great Lakes wave prediction model. Great Lakes Forecaster's Handbook, Section 8, September 14-18, 1987, NOAA National Ocean Service, 11 pp. (1987).

No abstract.

SCHWAB, D.J., and J.R. BENNETT. Lagrangian comparison of objectively analyzed and dynamically modeled circulation patterns in Lake Erie. Journal of Great Lakes Research 13(4):515-529 (1987).

Currents measured at 28 moorings in Lake Erie during May through October, 1979, were low-pass filtered to remove energy at diurnal, inertial, and higher frequencies. The current meter observations were interpolated to a regular grid over the lake by a new objective analysis technique, producing a stream function field which 1) conserves mass both locally and globally, 2) has values on the shores given by known river flows, 3) has the correct currents where they were measured, and 4) minimizes a function of squared vorticity in areas between the observations. In addition, a numerical, time-dependent, barotropic, rigid-lid circulation model was run using winds from six meteorological buoys on the lake as the forcing function. Twelve 5-day storm cases were selected for detailed Lagrangian analysis. At the beginning of each case, marker particles were released into the objectively analyzed and dynamically modeled flow fields at each of the 28 current meter mooring locations. Differences in the particle trajectories were analyzed by location and as a function of time. The results indicate that the circulation model shows some skill in generating positional differences as low as 8.5 km after 5 days compared to a mean path length of 14.9 km. They also show how numerical models and the objective analysis technique can be used to design more effective instrument deployment schemes for measuring lake and ocean circulation patterns.

SCHWAB, D.J., and E.W. LYNN. Great Lakes storm surge planning program (SSPP). NOAA Technical Memorandum ERL GLERL-65, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB88-119433/XAB) 9 pp. (1987).

This report describes a computer program for estimating maximum and minimum storm surge water levels for the Great Lakes. Storm surge water levels for a given wind speed and wind direction can be calculated for Lake Ontario, Central and Eastern Lake Erie, Western Lake Erie, Lake St. Clair, Lake Huron, Saginaw Bay, the eastern shore of Lake Michigan, the western shore of Lake Michigan, Green Bay, or Lake Superior. The program can be run on any PC-type computer.

SCHWAB, D.J., E.W. LYNN, and G.E. SPALDING. User's manual for GLERL Data Access System (GDAS). NOAA Technical Memorandum ERL GLERL-63, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB87-193926/XAB) 37 pp. (1987).

The GLERL Data Access System (GDAS) is a series of FORTRAN subroutines designed to aid in the storage and retrieval of data from time-series data bases (collections of time-series with a common start date, start time, duration, and recording interval). Each time-series within the data base is uniquely identified by a station identifier, a parameter descriptor code identifying the type of data, and a fixed height or depth relative to the water surface. Information about the time-series is contained in a GDAS header file; the data are stored in a GDAS data file. This report describes the format of GDAS files and the GDAS subroutines used to access GDAS files, and gives an example of how to use the GDAS subroutines.

TARAPCHAK, S.J., and C. Nalewajko. A review: Phosphorus-plankton dynamics and phosphorus cycling in aquatic systems. NOAA Technical Memorandum ERL GLERL-60, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB87-174009/XAB) 51 pp. (1987).

Phosphorus (P)-plankton dynamics is a scientifically challenging, continuously evolving discipline. Research historically has focused on the role of P as a limiting factor in primary and secondary production. Extensive efforts have been made to understand the eutrophication process, model P-limited phytoplankton growth, predict the outcome of the species competition, and understand the regenerative mechanisms that resupply orthophosphate (Pi) to algae. In the Great Lakes, research on P has focused primarily on water-quality monitoring programs and the use of P budget models to predict future changes in trophic state. However, to model production dynamics accurately in the Great Lakes system, additional studies on P cycling are required. This report briefly traces the development of scientific investigation into cultural eutrophication, identifies major research themes and problems in P--plankton dynamics and in aquatic P cycling, and summarizes basic and applied research on eutrophication and P cycling in the Great Lakes.

White, D.S., P.C. Klahr, and J.A. ROBBINS. Effects of temperature and density on sediment reworking by Stylodrilus heringianus (Oligochaeta: Lumbriculidae). Journal of Great Lakes Research 13(2):147-156 (1987).

A non-destructive, radio-maker system was used to follow sediment burial, or reworking rate, by the particle-feeding oligochaete Stylodrilus heringianus Claparede over a range of worm densities and water temperatures in laboratory microcosms. Marker layer burial rates were monitored for seven densities (30,000 to 134,000 worms m-2) while slowly altering the temperature from 10oC down to 4oC, up to 20oC, and then back to 10oC. From 10oC to 4oC, reworking rates decreased approximately 90%. When the temperature was increased above 4oC, reworking rates approached levels shown at the initial 10oC but remained relatively constant through the remainder of the experiment. It is assumed that reproductive activities, stimulated by the 4oC period, affected feeding activity. The reworking rate per worm was shown to be independent of the initial oligochaete density. Time dependent and depth dependent models were tested to examine the decline in observed reworking rates during the latter part of the experiment. There was a weak correlation between time and decreased reworking rates and a strong correlation between density and depth of feeding. Correlations suggested that reworking rates per worm remained similar over time, but the depth to which an organism fed increased with increasing worm density.

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