Population Biology of Steelhead Spawning Runs in Three Pennsylvania Tributaries to Lake Erie

Little is currently known about the population biology of steelhead (Oncorhynchus mykiss) that spawn in Pennsylvania's Lake Erie tributaries or the role of natural reproduction in supporting this fishery despite its popularity and importance. The goal of this study was to describe the population characteristics of steelhead spawning runs in Crooked Creek, Godfrey Run, and Trout Run, three Pennsylvania Lake Erie tributaries that are annually stocked with 80,000 to 200,000 yearling steelhead. From fall 1997 to spring 1999, returning adult steelhead were sampled during both fall and spring spawning runs using seines and backpack electrofishing gear. Sex was determined using external characteristics, total length was measured, and a scale sample was collected from each fish. Scales were analyzed to determine age, life history patterns, and relative contributions of wild and hatchery-reared fish to seasonal spawning runs. Male steelhead dominated sex ratios in both Godfrey Run and Trout Run during both seasons, while female steelhead were more prevalent in Crooked Creek. Stream-age 1 steelhead were predominant in both fall and spring runs in all three streams. During both seasons in all streams, the majority of males returned after spending only one summer in Lake Erie while most female steelhead returned at lake-age-2. The relative contribution of wild steelhead to Pennsylvania spawning runs was minimal in all three streams for both seasons. As a result, future success of Pennsylvania's steelhead fishery will likely require the continuation of annual tributary stocking of steelhead smolts.     

Biogeochemical Investigation of Big Creek Marsh,Lake Erie,Ontario

Geochemical composition of sediment, uptake of nutrients and metals by macrophytes, and nutrient and metal concentration in the water was investigated at six selected stations in Big Creek Marsh, Ontario. The maximum concentrations of Pb, Ni, Cu, Cr, and Zn in marsh sediment (86, 48, 38,119, and 383 μg/g dry weight, respectively), were lower than the concentration of these metals found in fine-grained surficial sediments of Lake Erie, and maximum concentration of As and Hg in marsh sediment (112 and 0.930 μg/g dry weight, respectively) were higher than As and Hg concentration in most of Lake Erie surficial sediments. Occurrence of DDT metabolites in marsh sediment reflects extensive use of DDT in the Big Creek drainage basin prior to 1970. Increase of total Kjeldahl Nitrogen and NH₄-N in marshwater was observed at a few sampling stations in November. Submerged macrophytes Myriophyllum, Chara, and Elodea sps. accumulated larger quantities of Pb, Cu, Ni, Cd, and Cr than emergent macrophytes at the stage of maximum development. Correlation between Ca and Pb, Cu, Ni, and Cr concentration in sampled macrophytes was observed; however, there was no correlation between Ca and Zn in these plants.     

Production and Respiration in Lake Erie Plankton Communities

Planktonic community metabolism (photosynthesis and respiration) was assessed in the oligotrophic east basin of Lake Erie, from November 2001 to October 2002 using O₂ and ¹⁴C methods. Areal gross production (AGP; mmol O₂ m⁻² d⁻¹) exceeded areal respiration (AR; mmol O₂ m⁻² d⁻¹) in the surface mixed layer for 69% of the observations during the study period. The median AGP:AR for the entire study period was 1.32. A significant positive relationship between AGP and AR existed, but AGP explained only 25% of the variation in AR. AGP:AR varied seasonally, being below 1.0 in the fall/winter of 2001 and in early spring 2002. High (>> 1.0) AGP:AR was observed in late spring (May) and AGP:AR remained > 1.0 for most of the summer stratified period (July–September). AGP:AR was > 1.0 in the fall of 2002, but the magnitude was less than observed during spring. The results supported traditional concepts of the seasonal production and consumption cycles in planktonic communities of large oligotrophic lakes. Parallel incubations of ¹⁴C uptake and gross O₂ production determined with the light and dark bottle method revealed a mean experimental gross photosynthetic quotient (PQ_G) of 1.29 ± 0.48, indicating that the ¹⁴C method used here had a variable but, on average, close relationship to gross production as it is commonly measured.     

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.     

Characterization of Surface-Associated Protozoan Communities in a Lake Erie Coastal Wetland (Old Woman Creek,Ohio)

Examination of surface-associated protozoa in Great Lakes coastal marshes has been minimal, although they play crucial roles in nutrient and energy transfer in similar systems. Spatio-temporal patterns of artificial substrate-associated protist and bacterial abundances are related to physico-chemical conditions at this “freshwater estuary.” Assemblages were sampled monthly (May-October) at upstream, downstream, and at two mid-estuarine sites. A total of 278 protistan taxa were observed, and greatest richness occurred in late June. Richness at the estuary mouth was consistently higher than upstream, possibly due to the influence of Lake Erie assemblages and variability in hydrology-driven habitat characteristics. PCA yielded two components accounting for 90% of total variance in species by sites data. Species abundances at the two mid-estuarine sites were most highly correlated, and taxa seasonally abundant at any one site tended to be abundant at others. Presence/absence data were used to calculate community similarity indices, and a permutation-computed test statistic compared the mean similarity of triplicate substrates in one month (at a given site) to the between-month similarity. Significant differences (α = 0.05) between some months (site by site) were observed, with a unique assemblage noted in October. Following classification into six functional feeding groups, bactivores (mainly heterotrophic microflagellates) and primary producers (mainly cryptomonads and chlamydomonads) dominated assemblages. Organisms in other functional groups comprised only 10–15% of observed taxa. A preponderance of bactivorous taxa is consistent with observations of a dense and metabolically active bacterial community associated with abundant paniculate organic matter in easily -resuspended surficial sediments.     

A Comparison of Spawning,Harvested, and Die-Off Rainbow Smelt, Osmerus Mordax, in Eastern Lake Erie

Rainbow smelt were collected in the area of Long Point, Lake Erie from 1) a commercial trawler, 2) spawning runs in streams, and 3) die-offs along beaches. The parasite Glugea hertwigi was found to have no effects on the fecundity or condition of smelt. However, infested smelt grew more slowly than uninfested ones. The percentage of infested smelt in die-offs was not significantly higher than in the spawning stock, suggesting that the parasite was not the primary cause of the mortality. Growth, maximum age, and fecundity of smelt in the samples were lower than in most other smelt populations for which data are available. Since there are no data available for Lake Erie smelt prior to or during the development of the fishery, it is not possible to assess if the observed population structure is the result of exploitation. Sex ratio changes suggest that spawning smelt may remix with the harvested stock gradually throughout the summer.     

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.     

Microplastic pollutants in the coastal dunes of Lake Erie and Lake Ontario

Microplastic particles, often studied as aquatic pollutants, have been recovered from coastal dunes along the shores of Lake Ontario and Lake Erie in New York and Pennsylvania. Surface and shallow sub-surface sand samples were collected from coastal dunes in 1 m² areas from 5 locations along Lake Erie: Sunset Bay, Dunkirk Harbor, Point Gratiot, and Canadaway Creek in New York and Presque Isle State Park Beach #11 in Pennsylvania. Samples were also collected from coastal dunes on Lake Ontario at Sandy Island Beach State Park, NY. Abundances, shapes, sizes, textures, and degradation of microplastics were characterized. Twenty-one of 26 samples yielded a variety of microplastics: pellets, fragments, and fibers. Larger microplastics (5.0–1.0 mm) were dominated by spheroidal and disk-shaped pellets with fewer fragments. Smaller microplastics (≤1.0 mm) were predominantly fibers and small fragments. Some microplastic particles exhibited evidence of degradation and weathering as a consequence of transport and exposure to the elements. The presence of microplastics in coastal dunes is attributable to aeolian transport from the adjacent beach.     

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.     

Food of Freshwater Drum in Western Lake Erie

The abundance of freshwater drum (Aplodinotus grunniens) suggests they play an important role in the Lake Erie ecosystem. Our analysis of freshwater drum digestive tracts and macrobenthic samples collected from western Lake Erie indicates that drum were selective feeders. Planktonic cladocerans and larval midges (Chironomidae) were the primary prey organisms eaten by drum. Young-of-the-year fed mostly on cladocerans, while yearling and older drum ate both cladocerans and midge larvae. Decapods, pelecypods, and fish were found only in the digestive tracts of drum longer than 250 mm. While the most abundant organisms in benthic samples were cladocerans (ephippial) and oligochaetes (89.5% by number), they constituted less than 1% of the diet. An evaluation of food selectivity, using Ivlev's index of electivity for benthic organisms, indicated that adult drum preferred midges to any other benthic food.     

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.     

The Entrainment and Deposition of Fine-Grained Sediments in Lake Erie

A series of entrainment and deposition experiments was performed with the general purpose of increasing our understanding of the parameters on which entrainment and deposition depend and the specific purpose of obtaining entrainment rates for a variety of sediments from the western basin of Lake Erie. The experiments were performed in an annular flume. A rotating top produced a turbulent flow which in turn exerted a turbulent shear stress on the sediments deposited on the bottom of the flume. Four different sediments from the western basin of Lake Erie were analyzed. Large variations in entrainment and deposition rates occurred and are shown to be dependent on the shear stress, water content (time after deposition), the type of sediment (grain size and mineralogy), and the manner of deposition. In the interpretation of the experiments, it is necessary to consider the frequency distribution of sediment properties as well as the average properties.     

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.     

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.     

Energy Relations in Cladophora Glomerata from Lake Erie

Photosynthesis and respiration measurements were made at lake temperatures with Cladophora glomerata collected from the eastern basin of Lake Erie. Although water temperatures varied from 10°C in May to almost 25°C in July, neither photosynthesis nor respiration showed any general increase in rates, even though there were wide daily fluctuations. Starch levels were low during the period of rapid growth but then increased until the time of sloughing. These data suggest that photosynthesis and respiration in Cladophora temperature-adapt and that a negative energy balance is not the cause of the mid-summer die-off.     

Modeling three-dimensional transport of microplastics and impacts of biofouling in Lake Erie and Lake Ontario

Studies in the oceans and The Great Lakes have found several orders of magnitude less plastic in surface samples than predicted by input estimates. Some plastic likely sinks after entering the water because it is naturally more dense than freshwater. For less dense particles, it has been proposed that biofouling, or the buildup of organic materials on the plastic, can cause them to become more dense and ultimately induce sinking. In this work we compare two different functional biofouling models: one basic algal growth population model and one model that assumes photosensitive defouling. We investigate the effects within the scope of a large-scale hydrodynamic model that includes advection, vertical diffusion, and sediment deposition applied to both Lake Erie and Lake Ontario. We find that deposition rates are dependent on the fouling method and lake depth. Lastly, we use the model to develop a first pass mass estimate for the sediment deposition rate in Lake Ontario.