Trace Metal Mineral Equilibria in Lake Erie Sediments

The thermodynamic tendency of metal phosphate and carbonate mineral phases to precipitate in Lake Erie sediments has been calculated by means of an ion-pair model of the interstitial water chemistry. The calculations suggest that detrital calcite, aragonite, and dolomite should be dissolving in the sediments, but that iron and manganese carbonates should be precipitating. Regenerated phosphate should be reacting with calcium, iron, manganese, and lead to form authigenic mineral phases and be removed from solution. Whitlockite, Ca₃(PO₄)₂, and not hydrozylapatite, Ca₅(PO₄)₃OH, is the predicted primary controlling phase for phosphate, although apatites are supersaturated and may be precipitating. Zinc and cadmium are apparently controlled by other mechanisms, perhaps as sulfide phases, mixed mineral phases, adsorption, and/or ion exchange equilibria.     

Mineralogy and Distribution of Fine-Grained Sediments in Little Traverse Bay,Lake Michigan

Little Traverse Bay, northeastern Lake Michigan, contains sediments ranging in mean grain size from about 1.5? around the bay margins to 7? in the central portion. Mineralogy of the fine-grained fraction of these sediments show the four main mineral groups, quartz, feldspars, clays, and carbonates to have decidedly different distributions within the bay. Quartz and feldspar reach maxima near the center of the bay, while carbonates are highest around the edge. Clay mineral abundance reaches three separate maxima in regions characterized by very poorly sorted sediment. There are two important sources of these sediments, extensive outcrops of Devonian limestones and dolomites along the south shore of the bay and bluffs of reddish glacial till along the northwestern shoreline. Materials from these areas are transported eastward to the bay head by longshore transport incurred by the prevailing westerly winds and then return westward along the deep central trough of the bay as the wind-induced setup is relieved. Essentially all of the calcite and much of the dolomite entering Little Traverse Bay undergoes dissolution during transport resulting in the carbonate-poor sediments of the bay floor.     

Preliminary Investigation of the Algal Flora in the Sediments of Lake Erie

The algae in a 45-cm-long sediment core taken in the eastern basin of Lake Erie were examined to determine the extent and applicability of that flora in reflecting the history of the lake. Asterionella formosa, Melosira islandica, M. italica, Stephanodiscus niagarae, and Tabellaria fenestrata were the most abundant diatoms encountered. Quantitative diatom profiles reported as cells/cm³ sediment and relative abundance profiles each provide a contrasting history of post-settlement Lake Erie. In light of the known history of the lake, the relative frequency profiles appear to be most applicable. The C/P index of trophic status and diatom diversity support those profiles. The occurrence of non-diatom algae in the sediments was inadequate for detailed analyses; however, occurrence did correspond to the trophic history determined by the diatoms. Botryococcus braunii, Cosmarium formosulum, Pediastrum boryanum, and Staurastrum gracile were most commonly encountered.     

Phosphate Characteristics and Bioavailability of Suspended Sediments from Streams Draining into Lake Erie

Suspended sediments from major U.S. tributaries draining into Lake Erie were analyzed for phosphorus. Analyses included: sediment concentration, reactive and total filtered P, and total P on water samples. Recovered sediment total P was determined by perchloric and persulfate extraction. Sediment was fractionated for NaOH-P citrate-dithionite-bicarbonate (CDB)-P, HCl-P, and organic P. New York streams had the highest suspended solids and the lowest content of most sediment fractions except HCl-P. NaOH-P and CDB-P were highest in sediments from Ohio tributaries; these fractions are considered to be bioavailable with NaOH-P more available than CDB-P. Digestion with perchloric acid consistently removed more P than the persulfate method. The difference in the two methods was negatively correlated with HCl-P.     

Lake Erie in Mid-Winter

The results of four surveys of Lake Erie during mid-winter are presented here. The most recent survey, from February 15 to 17, 1977, was conducted during an exceptionally cold winter to determine whether six weeks of complete ice-cover had led to low levels of oxygen concentration in the lake. The results showed that all parts of the lake, even the shallow, normally highly productive areas, contained acceptable levels of oxygen. Apparently, production of oxygen by a small phytoplankton population counterbalanced a fairly low uptake of oxygen and maintained the level of oxygen concentration in most of the water above 90% saturation. The 1976-77 winter phytoplankton biomass was low (0.1 to 1.0 gm biomass per m³) and consisted mostly of diatoms. It appears that some of the phytoplankton were photo-synthetically active under 70 cm of ice and 23 m of water. All surveys of the lake showed the water to be virtually isothermal at a temperature just above the freezing point of water. The maximum temperature differences observed were about 0.2° in magnitude and were found in the East Basin. Nevertheless, the slight temperature differences apparently caused density currents under the ice, which resulted in lowered oxygen concentrations in the deepest part of the East Basin.     

Geochemical Availability of Some Trace and Major Elements in Surficial Sediments of the Detroit River and Western Lake Erie

Surficial bottom sediment from twenty locations in the Detroit River and western Lake Erie has been analyzed for potentially available Ba, Be, Cd, Cr, Co, Cu, Pb, Mn, Mo, Ni, P, V, and Zn. The highest concentrations of all but one of these elements were found at a station at the river-lake interface very close to a dumping ground. The environmental mobility of Cd, Zn, Co, Pb, Cr, Ni, and P is controlled by hydrous iron oxides, whereas V and Mo is controlled by aluminosilicates. The iron oxide phase exhibits a very high sorption capacity for phosphorus (molar adsorption coefficient = .361) which is attributed to the high loadings of Fe and P at the confluence of the Rouge and Detroit rivers as well as continuous inputs along the length of the Detroit River. It is suggested that phosphorus controls instituted in the 1970s will probably result in the iron oxide phase having greater sorption capacity for toxic metals because of the decreasing competition from phosphorus for binding sites.     

Impact of Power Plant Entrainment of Ichthyoplankton on Juvenile Recruitment of Four Fishes in Western Lake Erie in 1975–77

The effect of power plant entrainment on juvenile recruitment of four species of ichthyoplankton in western Lake Erie was investigated. Of the four species studied—gizzard shad (Dorosoma cepedianum), white bass (Morone chrysops), walleye (Stizostedion vitreum) and freshwater drum (Aplodinotus grunniens)—it was found that the effect on walleye year class strength is minimal while the effect on gizzard shad recruitment may possibly be significant in terms of overall impact on the community ecology of the western basin. This aspect of the impact of power plant entrainment should be further investigated. It was estimated that total juvenile recruitment of these four species would increase by 742 individuals per acre if all power plant entrainment were eliminated.     

Relationships Among Zoobenthos,Sediments, and Organic Matter in Littoral Zones of Western Lake Erie and Saginaw Bay

Zoobenthos and sediments from the littoral zones in western Lake Erie and Saginaw Bay were sampled. Littoral zones were inhabited mostly by infaunal species of Tubificidae and Chironomidae. Particle size and organic content of sediments were highly and significantly correlated with abundance and mean size of zoobenthic groups; weight and mean size of zoobenthos were greatest in organically rich silts and clays, and least in organically poor sands. Relative abundance and mean size of zoobenthos in sands were greatly influenced by the proximity of fine-grained sediments. Sandy sediments next to muddy sediments had zoobenthic groups with weights and mean size similar to those in adjacent muddy sediments. Low to moderate densities of submerged macrophytes on muddy sediments had a small, non-significant (p>.05) impact on zoobenthic abundance and composition compared to similar sediments without macrophytes. In well-mixed littoral zones, with sediments of diameters less than 1.5 mm, particle size and organic matter in sediment may serve as a reliable index to standing stocks of zoobenthos.     

Distribution of Freshwater Ostracodes in Lake Erie

Samples collected from the Lake Erie sediment-water interface in 1975 indicate the presence of few live shelled crustaceans (ostracodes). Of the 26 species identified only one, Candona caudata, can be considered as successful today in Lake Erie. Cytherissa lacustris and Candona subtriangulata, primarily recovered as empty shells in this study, indicate that these species have become extinct because of chemical and/or physical change sometime during the last 100 years in Lake Erie.     

Multiple Estimates of Lake Erie Evaporation

Evaporation from large lakes cannot be measured directly, but several methods have been developed to compute lake evaporation. Because of the Great Lakes data limitations, evaporation determined by a single method is’ not sufficiently reliable and requires verification of accuracy by different methods. Monthly evaporation from Lake Erie was derived by the water budget, selected mass transfer, and the energy budget approaches. The period of record varies with the availability of data, 1937-68 for the water budget and mass transfer methods, and 1952-1968 for the energy budget method. Evaporation determined by the water budget method was used to provide control for the other methods. The evaporation rates varied from -9 to 25 cm/month with periods of low, median, and high annual evaporation averaging approximately 80, 90 and 100 cm. The analysis of results indicates that reasonably accurate evaporation estimates during the year can be obtained by the water budget and the modified Lake Hefner mass-transfer equations.     

Modelling Ice Dissipation in Eastern Lake Erie

A previously developed mathematical model, which considered both the heat exchange processes at the air-ice interface and the ice transport rate via the Niagara River Was used to simulate the ice dissipation process in eastern Lake Erie. The model, which assumed the ice thickness to be constant over the lake, has been further developed to take into account variable ice thickness. Buffalo meteorological data were used for the computation of the net heat exchange at the air-ice interface. Results of the model application illustrate the relative importance ofin-lake ice melt to ice transport via the Niagara River during the dissipation period. Model results were found to give reasonably good agreement with the limited ice information available for the 1976 dissipation period.     

Calcium Carbonate in Postglacial Lake Erie Sediment

Geotechnical, geochemical, electron-microscopic and biostratigraphic investigation of a 16.8–m long core of a postglacial lacustrine mud collected from the central Lake Erie basin revealed zones containing up to 30% calcite. These zones were associated with a very fine sediment, 80% of which was finer than 4 y.m. Shear strength values of the sediment ranged from 2 kN/m² near the lake bottom to about 9 kN/m² close to the Pleistocene boundary. The concentration of CaO was positively correlated with the concentration of inorganic C and Sr. The concentration of SiO₂, A1₂O₃, Fe₂O₃, K₂O, and Rb gradually decreased with depth. The major crystalline phases were illite (44 wt %), chlorite (10 -13 wt %), calcite (6 - 30 wt %), quartz (6 - 20 wt %), albite (6 - 9 wt %), K-feldspar (2 wt %), and dolomite (2 wt %). The shells of mollusc species present in the lower portion of the postglacial sedimentary column indicated that the carbonate-high sediments were deposited in warmer water than the carbonate-low sediments above and between them.     

Potential Strategies for Recovery of Lake Whitefish and Lake Herring Stocks in Eastern Lake Erie

Lake Erie sustained large populations of ciscoes (Salmonidae: Coregoninae) 120 years ago. By the end of the 19^th century, abundance of lake whitefish (Coregonus clupeaformis) had declined drastically. By 1925, the lake herring (a cisco) population (Coregonus artedii) had collapsed, although a limited lake herring fishery persisted in the eastern basin until the 1950s. In the latter part of the 20^th century, the composition of the fish community changed as oligotrophication proceeded. Since 1984, a limited recovery of lake whitefish has occurred, however no recovery was evident for lake herring. Current ecological conditions in Lake Erie probably will not inhibit recovery of the coregonine species. Recovery of walleye (Sander vitreus) and efforts to rehabilitate the native lake trout (Salvelinus namaycush) in Lake Erie will probably assist recovery because these piscivores reduce populations of alewife (Alosa psuedoharengus) and rainbow smelt (Osmerus mordax), which inhibit reproductive success of coregonines. Although there are considerable spawning substrates available to coregonine species in eastern Lake Erie, eggs and fry would probably be displaced by storm surge from most shoals. Site selection for stocking or seeding of eggs should consider the reproductive life cycle of the stocked fish and suitable protection from storm events. Two potential sites in the eastern basin have been identified. Recommended management rocedures, including commercial fisheries, are suggested to assist in recovery. Stocking in the eastern basin of Lake Erie is recommended for both species, as conditions are adequate and the native spawning population in the eastern basin is low. For lake herring, consideration should be given to match ecophenotypes as much as possible. Egg seeding is recommended. Egg seeding of lake whitefish should be considered initially, with fingerling or yearling stocking suggested if unsuccessful. Spawning stocks of whitefish in the western basin of Lake Erie could be utilized.     

Wave Action and Bottom Shear Stresses in Lake Erie

For Lake Erie, the amplitudes and periods of wind-driven, surface gravity waves were calculated by means of the SMB hindcasting method. Bottom orbital velocities and bottom shear stresses were then calculated using linear wave theory and Kajiura's (1968) turbulent oscillating boundary layer analysis. These calculations were made for south-west and north wind directions and a steady wind speed of 40 km hr^?1. Calculated bottom shear stresses are related to the textural properties of surficial Lake Erie sediments as determined by Thomas et al. (1976). The bottom shear stresses, especially under prevailing southwest wind conditions, control the textural characteristics of surface sediments in Lake Erie. In particular, wave-induced bottom shear stresses are probably the most important energy source for sediment entrainment.     

Lyngbya wollei in western Lake Erie

We report on the emergence of the potentially toxic filamentous cyanobacterium, Lyngbya wollei as a nuisance species in western Lake Erie. The first indication of heavy L. wollei growth along the lake bottom occurred in September 2006, when a storm deposited large mats of L. wollei in coves along the south shore of Maumee Bay. These mats remained intact over winter and new growth was observed along the margins in April 2007. Mats ranged in thickness from 0.2 to 1.2 m and we estimated that one 100-m stretch of shoreline along the southern shore of Maumee Bay was covered with approximately 200 metric tons of L. wollei. Nearshore surveys conducted in July 2008 revealed greatest benthic L. wollei biomass (591 g/m² ± 361 g/m² fresh weight) in Maumee Bay at depth contours between 1.5 and 3.5 m corresponding to benthic irradiance of approximately 4.0–0.05% of surface irradiance and sand/crushed dreissenid mussel shell-type substrate. A shoreline survey indicated a generally decreasing prevalence of shoreline L. wollei mats with distance from Maumee Bay. Surveys of nearshore benthic areas outside of Maumee Bay revealed substantial L. wollei beds north along the Michigan shoreline, but very little L wollei growth to the east along the Ohio shoreline.     

Seasonal Variation of Nutrient Limitation in Western Lake Erie

Monthly nutrient enrichment experiments were performed from April through October, 1983, to identify growth limiting nutrients of natural phytoplankton assemblages collected from a station in the Pigeon Bay waters off the north shore of Lake Erie's western basin. Data from these experiments suggest that silica was the major limiting nutrient in April, phosphorus was the major limiting nutrient in May-September, and trace metals were limiting in October. These results show that nutrient enrichment experiments should be performed often enough to account for seasonal changes in the physicochemical environment as well as seasonal succession in phytoplankton. The conclusion that phosphorus was the major limiting nutrient in summer is different from the conclusions of the late 1960s and early 1970s that nitrogen was the major limiting nutrient in the summer in the western basin and suggests a possible shift from nitrogen to phosphorus limitation. Pigeon Bay nutrient trend data show that summer nitrate:soluble reactive phosphorus ratios have increased from approximately 4 in the late 1960s to over 40 in the late 1970s and early 1980s, corroborating that a shift has probably occurred. This shift in nutrient limitation is probably due to reduced bioavailable phosphorus loadings and increased nitrate loadings to the western basin. The southern portion of the western basin is physicochemically different from the northern portion and may not have responded in the same manner.     

The effect of Lake Erie water level variations on sediment resuspension

Variability in Lake Erie water levels results in variations of the fluid forces applied to the lake bed by free-surface gravity wind-waves. An increase in the bed stress may re-suspend sediment deposited years earlier. This study identifies areas of possible non-cohesive sediment mobilization in response to the forcing conditions and water levels present in Lake Erie. Observations from NOAA buoy 45005 were used to identify wave events generated by a variety of atmospheric forcing conditions. For each event, numerical predictions of significant wave height, wave period, and water level from the Great Lakes Forecasting System (GLFS) were used to characterize the wave event variability over the lake. The Shields parameter was estimated at each 2 km × 2 km grid cell with the local wave forcing as predicted by GLFS assuming an estimate of the wave-induced friction factor. In the Cleveland harbor region of the central basin, the Shields parameter was also estimated by assuming uniform wave conditions as observed by NOAA buoy 45005. The “contour of incipient motion” for both variable and uniform wave events was defined as the offshore contour where the Shields parameter exceeds the critical limit for motion. Comparisons with a radiometrically corrected image from Landsat-7 showed that the spatially varying wave events from GLFS were in qualitative agreement with the satellite observations. A sensitivity analysis of wave height, wave period, and grain size showed the contour of incipient motion to be the most sensitive to wave period. Calculations performed for record high and low water levels showed that the incipient motion of non-cohesive sediments in the relatively flat central basin to be the most sensitive to the historic hydrologic variability present in Lake Erie.     

Diatoms abound in ice-covered Lake Erie: An investigation of offshore winter limnology in Lake Erie over the period 2007 to 2010

The limnology of offshore Lake Erie during periods of extensive (> 70%) ice cover was examined from ship borne sampling efforts in 2007 to 2010, inclusive. Dense and discrete accumulations of the centric filamentous diatom Aulacoseria islandica (> 10 μg Chl-a/L) were located in the isothermal (< 1 °C) water column directly below the ice and only detectable in the ship wake; viable phytoplankton were also observed within ice. Evidence from these surveys supports the notions that winter blooms of diatoms occur annually prior to the onset of ice cover and that the phytoplankton from these blooms are maintained in the surface waters of Lake Erie and reduce silicate concentrations in the lake prior to spring. The mechanisms by which high phytoplankton biomass rise at this time of year requires further investigation, but these winter blooms probably have consequences for summer hypoxia and how the lake responds to climate change.     

Unionid mussels from nearshore zones of Lake Erie

Concern exists that the introduction of dreissenid mussels following long-term effects of pollution may have completely eliminated native mussel species from Lake Erie. Natural seiche events were used to facilitate surveys for live unionids on five occasions in the western basin of Lake Erie and Sandusky Bay between 2007 and 2009, and beach and estuary surveys were conducted at numerous additional sites between 2004 and 2009. Sixteen unionid species were found living in or near Lake Erie, including six sites in the nearshore zone of the lake. Each community consisted of live individuals from two to eight species, and evidence included live and/or fresh dead material from several state listed species at multiple sites. Where estimated, the mean overall density was low at 0.09 unionids/m², although similar to other known unionid refuges in the lower Great Lakes. While the ephemeral nature of seiche events makes them a limited survey tool, their application combined with increasing numbers of fresh shells washing ashore over the past few years indicates that unionids are extant in the western basin of Lake Erie, and may further suggest that conditions may be improving for native mussel species.