The New Zealand mud snail (Potamopyrgus antipodarum) is an invasive species in Europe, Japan, Australia, and North America. In the western United States it is a species of special concern where population densities in some rivers and streams are very large (∼300,000 per m²) and considerable ecological effects of its presence have been reported. Much less about the effects of this species is known in the Great Lakes, where the snail was found in Lake Ontario and the St. Lawrence River in 1991. Here we report the occurrence of the snail in Lake Erie. Two P. antipodarum were collected in 18 m deep water (sampling range 5–18 m) in Lake Erie off shore of Presque Isle State Park near Erie, Pennsylvania in the summer of 2005 and others were collected off of Sturgeon Point in Lake Erie (sampling range 5–20 m) south of Buffalo, NY and in the central basin of Lake Erie (18 m) in 2006. This finding demonstrates that this species continues to expand its range in the Great Lakes. The range expansion increases the likelihood that it may become established in rivers and streams emptying into the Great Lakes where higher densities and greater ecological damage may result.

Using laboratory experiments, we assessed the effect of temperature and predator density on consumption of trout eggs by crayfish. We quantified the effect of four temperature ranges (2–3, 4–5, 7–8, and 10–12°C) on consumption of lake trout (Salvelinus namaycush) and rainbow trout (Oncorhynchus mykiss) eggs by a native (Orconectes propinquus) and an exotic (Orconectes rusticus) crayfish found in the Great Lakes. Mean individual consumption ranged from 0.1 to 1.5 lake trout eggs per day and from 1.0 to 5.5 rainbow trout eggs per day, respectively. Temperature influenced consumption for O. rusticus feeding on rainbow trout eggs but not O. propinquus. The effect of conspecific predator competition on rainbow trout egg consumption was evaluated using three densities of crayfish (1, 5, 10 per tank). For O. rusticus, mean individual consumption rate was higher at the lowest crayfish density (1 crayfish/tank) than at medium (5 crayfish/tank) or high (10 crayfish/tank) densities. A similar conspecific effect was not evident in O. propinquus and total consumption per unit area increased with crayfish density. The effect of competition among crayfish species on consumption of rainbow trout eggs was examined by comparing feeding rates at high crayfish abundance levels in single and mixed species treatments. Mixed species interactions did not significantly alter crayfish feeding rates. Results from these experiments provide empirical data to aid in modeling how temperature and predator density affect lake trout egg predation rates in the field.

Lake Erie and its tributaries have experienced extensive changes in environmental conditions and community structure during recent decades. To assess the relative importance of environmental conditions in determining fish community composition, fish communities and their associated environmental conditions were sampled from the lower reaches and mouths of the tributaries flowing into the northeastern basin of Lake Erie. These data were used to assess relationships between habitat and fish community composition on spatial and temporal scales using correspondence analysis and canonical correspondence analysis. Multivariate analyses revealed that the fish assemblage was size structured and related to water chemistry but also showed influences due to temperature, sampling date and aquatic macrophytes. The community composition showed the effects of biotic interactions, predominantly negative predator-prey associations, but there were also assemblage differences specific to particular tributaries and sampling methodologies.

This study presents the Lake Okeechobee Environment Model (LOEM), a three-dimensional (3D) hydrodynamic, sediment, water quality, and submerged aquatic vegetation (SAV) model of Lake Okeechobee, Florida. The LOEM is developed under the framework of the EFDC model (Hamrick 1992). Lake Okeechobee is the largest subtropical lake in North America (1,730 km²), it is very shallow (mean depth 2.7 m), and it includes a littoral habitat that makes up 20% of its area. The LOEM is calibrated, verified, and validated to 3 years of water quality and SAV data. The water quality results are consistent with observed data from 25 locations in the lake. The model is capable of reproducing key water quality characteristics of the lake without having to resort to extensive, site-specific parameter manipulations. The SAV model is calibrated using measured SAV data in the lake. The SAV model is capable of representing the spatial and temporal variations of SAV variations in the lake well. The LOEM is applied to study water quality and SAV processes in the lake. The model results are consistent with observed data indicating that algal growth in the lake is primarily nitrogen limited in the summer and nitrogen and light co-limited in the winter. Lower water elevation generally leads to larger SAV area. SAV can have positive impact on the lake water quality by reducing algae concentration. The calibrated, verified, and validated LOEM model serves as a useful tool to support lake management.

Lake Erie's food web has been dramatically modified by exotic species. Both exotic dreissenid mussels and the round goby Neogobius melanastomus have shifted the food web from a pelagic-based to a benthic-based one, potentially creating a new pathway for contaminant transfer to top predators. Before the invasion of round gobies, few predators of dreissenids occurred in Lake Erie, allowing contaminants to be confined to these benthic organisms. The invasion of the round goby has produced a new pathway through which these contaminants can enter the food web. To characterize heavy-metal transfer through this new food web and to assess risk to humans, water, surficial sediment, dreissenid, round goby, and smallmouth bass Micropterus dolomieui samples were collected at three sites during summers, 2002 and 2003, and analyzed for total lead (Pb), total mercury (Hg), and methyl mercury (MeHg). In addition, we compared smallmouth bass Pb and Hg concentrations to those measured in 1993/1994, before round gobies were prevalent. Pb biodiminished and MeHg biomagnified through the food web to smallmouth bass; patterns were similar among our three sites. Total Pb concentrations in smallmouth bass were higher before the incorporation of round gobies into their diet. We attributed this decline to changes in food web structure, changes in contaminant burdens in prey, or declines in sediment Pb concentrations in Lake Erie. By comparison, Hg concentrations in smallmouth bass changed little, before and after the round goby invasion, possibly due to a shift in diet that increased growth. Despite a decline in sediment Hg concentrations in Lake Erie, smallmouth bass continued to accumulate Hg at historical rates possibly because of their high consumption rates of benthivorous round gobies. As smallmouth bass continue to consume round gobies during their lives, their Hg concentrations may well continue to increase, potentially increasing the risk of Hg contamination to humans.

A two-dimensional numerical model was developed to study dissolved oxygen (DO) kinetics in a dredged Lake Erie tributary. The model design was aimed to specifically address the fact that many tributaries to the Great Lakes are dredged periodically for navigation, and that resultant changes in morphology and hydraulics can have significant impacts on DO. Due to the greater depths caused by dredging, river velocities slow considerably and vertical mixing is not as effective, leading to thermal stratification and potential short-circuiting of warmer upstream flow. The model solves the two-dimensional (laterally averaged) hydrodynamic and mass balance equations to simulate transport and transformation relevant to dissolved oxygen using an alternating direction, implicit finite difference method. Effects of oxygen-demanding pollutants from municipal and industrial discharges and also from nonpoint sources are included. A model application was developed for the Black River (Ohio), a tributary of Lake Erie. The river is dredged periodically, becomes stratified during the low flow summer months, and is affected by changing lake levels associated with seiching in Lake Erie. After calibration and confirmation, the model was used as a diagnostic tool to understand the impact of various loading sources on low DO levels observed along the bottom of the river. It is shown that sediment oxygen demand (SOD), combined with the river hydraulics, is the primary cause for low DO levels in the Black River.

Little is known about the ecology of round goby (Neogobius melanostomus), an invasive benthic fish, in the profundal zone of the Great Lakes. In April 2002–2005 we caught increasing numbers of round gobies with a bottom trawl in the 45–150 m depth range of southwestern Lake Ontario. In 2005, we examined gut contents of 30 round gobies from each of three depths, 55, 95, and 130 m, and qualitatively compared gut contents with density of benthic invertebrates determined by Ponar grabs. Round goby guts contained mostly Dreissena spp. and opposum shrimp, Mysis relicta (Mysis); the frequency of occurrence of dreissenids in guts decreased with depth, whereas the frequency of occurrence of Mysis in guts increased with depth. Abundance of these invertebrates in the environment followed the same pattern, although dreissenids of optimum edible size (3–12 mm) were still abundant (1,373/m²) at 130 m, where round gobies primarily consumed Mysis, suggesting that round gobies may switch from dreissenids to more profitable prey when it is available. Other food items were ostracods and fish, with ostracods generally eaten by smaller round gobies and fish eaten by larger round gobies. Occurrence and increasing abundance of round gobies in the profundal zone and predation on Mysis by round goby could have far-reaching consequences for the Lake Ontario fish community.

Alewives (Alosa pseudoharengus), the major prey fish for Lake Ontario, contain thiaminase. They are associated with development of a thiamine deficiency in salmonines which greatly increases the potential for developing an early mortality syndrome (EMS). To assess the possible effects of thiamine deficiency on salmonine reproduction we measured egg thiamine concentrations for five species of Lake Ontario salmonines. From this we estimated the proportion of families susceptible to EMS based on whether they were below the ED20, the egg thiamine concentration associated with 20% mortality due to EMS. The ED20s were 1.52, 2.63, and 2.99 nmol/g egg for Chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch), respectively. Based on the proportion of fish having egg thiamine concentrations falling below the ED20, the risk of developing EMS in Lake Ontario was highest for lake trout, followed by coho (O. kisutch), and Chinook salmon, with the least risk for rainbow trout (O. mykiss). For lake trout from western Lake Ontario, mean egg thiamine concentration showed significant annual variability during 1994 to 2003, when the proportion of lake trout at risk of developing EMS based on ED20 ranged between 77 and 100%. Variation in the annual mean egg thiamine concentration for western Lake Ontario lake trout was positively related (p < 0.001, r² = 0.94) with indices of annual adult alewife biomass. While suggesting the possible involvement of density-dependent changes in alewives, the changes are small relative to egg thiamine concentrations when alewife are not part of the diet and are of insufficient magnitude to allow for natural reproduction by lake trout.

We describe the diet and prey selectivity of lean (Salvelinus namaycush namaycush) and siscowet lake trout (S. n. siscowet) collected during spring (April–June) from Lake Superior during 1986–2001. We estimated prey selectivity by comparing prey numerical abundance estimates from spring bottom trawl surveys and lake trout diet information in similar areas from spring gill net surveys conducted annually in Lake Superior. Rainbow smelt (Osmerus mordax) was the most common prey and was positively selected by both lean and siscowet lake trout throughout the study. Selection by lean lake trout for coregonine (Coregonus spp.) prey increased after 1991 and corresponded with a slight decrease in selection for rainbow smelt. Siscowet positively selected for rainbow smelt after 1998, a change that was coincident with the decrease in selection for this prey item by lean lake trout. However, diet overlap between lean and siscowet lake trout was not strong and did not change significantly over the study period. Rainbow smelt remains an important prey species for lake trout in Lake Superior despite declines in abundance.

Early work indicated that wet deposition of radioactive fallout to the water surface of a lake greatly exceeded dry, when calculated as annual averages. To test whether this result also applies to the deposition rates of soluble trace gases from the lower atmosphere, data collected at land sites near Lake Champlain have been used to estimate deposition rates to the lake itself, using an analysis of the wind speed-up factor as an intermediate step. The contribution of dry deposition of the major nitrogen and sulfur chemical species is estimated to have been less than 20% of the total atmospheric deposition. However, this result must not be extrapolated to the watershed in which Lake Champlain resides, since evidence obtained elsewhere indicates that the dry deposition contribution over the entire watershed will likely be similar to the wet. The analysis indicates that for the period from 1992 to 1997 the annual total deposition rates of oxidized nitrogen and sulfur ranged from 300 to 500 tonnes per year and 600 to 1,100 tonnes per year, respectively.

Submerged aquatic vegetation (SAV) distribution and coverage were quantified in two bays of Lake Ontario in 1972, 1980 (1982), and 1999–2002, using a combination of aerial photograph interpretation (API), hydroacoustics, and rake sampling. The three methods gave similar estimates of SAV presence in 2002, supporting our use of API for quantifying SAV changes across decades in bays of a large lake. The SAV coverage in Sodus Bay increased by 5% between 1972 and 1980 and by 35% between 1980 and 1999–2002 whereas the maximum depth of SAV colonization extended from 5.5 to 6.4 m during this period. In Chaumont Bay, the SAV coverage tripled while its maximum depth of occurrence increased from 5.1 to 6.1 m from 1982 to 2002. Although the difference in SAV coverage between 1972 and 1980 was not larger than the difference between consecutive years in the 2000s, the large increase in SAV coverage between the 1980s and 2000s represents a major ecosystem change in these bays. This change was likely caused by increased water clarity in Lake Ontario, which could be associated with the implementation of the Great Lakes Water Quality Agreement (GLWQA) and the dreissenid mussel invasion. Although other factors such as water level, wave exposure, bottom slope, and sediment nutrients may be important, they have not changed in a fashion that would predict local increases of SAV coverage.

Establishment of nonindigenous species (NIS) has emerged as one of the leading environmental problems in the Great Lakes basin over the past quarter century. The purpose of this study was to assess responses by government agencies regarding allocation of funding to NIS projects between 2000 through 2005. NIS is considered a major and increasing problem by eight of ten major funding agencies in the basin. Despite this, total funding decreased from $5.1 to $3.2 million dollars per annum and the number of projects supported declined concomitantly from 145 to 98 during this period. Control or ecosystem effects received the greatest allotment of resources and represented the largest number of projects. Non-taxonomic specific topics, including risk assessment and ballast tank assessment and management, received more funding than any taxon-specific projects and comprised the majority of studies on prevention, spread, and socioeconomic impacts of NIS. Among the latter, fish and Dreissena mussels were the most popularly funded topics, and comprised the largest contribution to ecosystem effects and biology studies. Control studies principally addressed sea lamprey, round gobies and carp species. Prevention studies had the highest funding rate per capita ($ per study). Surprisingly, no clear shifts occurred with respect to the relative importance of projects pertaining to prevention over the period studied despite the recognized importance of this aspect of research.

Portage Lake is situated near the center of the Keweenaw Peninsula and is connected to Lake Superior via lengthy (> 7 km) navigation channels. Using moored thermistor records and meteorological data, we examine how changes in lake stratification are related to surface winds and heat flux. Frequent episodes of full water column mixing are observed throughout the summer. Convective mixing through surface cooling appears to be an important agent responsible for these events, as all occur during cold air outbreaks and when the net heat flux is directed out of the lake (negative). However, wind-induced mixing is also implicated in contributing to some vertical mixing events, as evidenced by two events initiated during a period of strong winds and declining, but not yet negative, heat fluxes. Our analysis indicates that each time the water column restratifies, it tends to become more susceptible to convectively-driven overturn during cold air outbreaks. This tendency is quantified by the estimated time over which surface cooling due to a specified set of conditions, characteristic of a cold air outbreak, would reduce the temperature contrast between the upper and lower layers by half. This time declines by more than an order of magnitude for successive restratification events observed in the summer of 1999. Our analysis also reveals successive formation and dissolution of a diurnal surface mixed layer in an otherwise homogeneous water column during a 10-day period of August 1999. This is attributed to the combination of relatively light winds and negative daily net heat fluxes.

Lake trout (Salvelinus namaycush) in Lake Mistassini, Quebec, were investigated to determine whether they resembled the lean and siscowet morphotypes of Lake Superior and Great Slave Lake. Lake trout caught in deep water were predicted to resemble the siscowet morphotype and to be better adapted for vertical migration (i.e., low percent buoyancy) than those caught in shallow water. The research objectives were to 1) identify groups based on shape, and 2) determine whether shape was associated with other morphological traits (fin length, buoyancy, color), ecology (habitat depth, diet), and life history (size at adulthood). Eighty-five lake trout were collected from three depth zones. At least two phenotypes exist in Lake Mistassini. A shallow-water form (< 50-m depth), identified by its streamlined shape, was dark in color and high in percent buoyancy. A deep-water form (> 50-m depth), identified by a deep anterior-body profile, was light in color and lower in percent buoyancy than the shallow-water form. Absolute buoyancies were relatively high in both forms; therefore, the deep-water form did not appear well-adapted for vertical migration. Opossum shrimp (Mysis relicta) were more frequent and abundant in stomachs of deep-bodied trout. All deep-bodied trout (minimum 32-cm SL) had reached adulthood, whereas immature streamlined individuals were as long as 49 cm in SL. The deep-bodied form resembled humper lake trout, a lesser-known third morphotype from Lake Superior. A humper-like morphotype in Lake Mistassini, and the apparent absence of a siscowet-like morphotype, challenges the previously-held hypothesis that humpers resulted from an introgression of leans and siscowets.

In southern Lake Malawi, seasonal pelagic chlorophyll means were 1.0 ± 0.3 μg L⁻¹ in the deep mixing season (DMS) (May–August), 0.8 ± 0.3 μg L⁻¹ in the dry stratified season (DSS) (September to November) and 0.7 ± 0.3 μg L⁻¹ in the wet stratified season (WSS) (December to April). Despite the low variability in chlorophyll, there was a wide range in chlorophyll specific photosynthetic activity. The photosynthetic parameters, P^b_m (the light saturated rate) and α^b (the light limited slope), varied significantly among seasons and were highly positively correlated, with lowest values in the DSS and highest values in WSS. During deep mixing, P^b_m did not covary with α^b; and the light saturation index, E_k (=Pb_m/α^b), varied in response to changes in α^b rather than in P^b_m. Phytoplankton appeared to be nutrient deficient at all times but less deficient during deep vertical mixing in the DMS. Average daily rates of integrated phytoplankton primary productivity were lowest in the DSS (337 mg C m⁻² d⁻¹) and highest in the WSS (629 mg C m⁻² d⁻¹) despite nearly identical mean chlorophyll concentrations. Along a near shore transect off the Linthipe River, chlorophyll concentrations were higher and more variable (1.4 ± 1.3 μg L⁻¹), phytoplankton were not strongly nutrient deficient and chlorophyll specific photosynthetic activity was as high or higher than at the offshore station. Estimates of phytoplankton productivity in this tropical great lake must account for spatial and temporal variability in photosynthetic parameters imposed by seasonal changes in mixing dynamics.

Lake trout management and restoration make use of age-structured population models that incorporate parameters to represent movement among management areas, and harvest quotas are based on proportions of stocked fish remaining in and moving out of areas of release. We investigated movements of lake trout in U.S. waters of Lake Huron based on spatial and temporal distributions of coded-wire-tag (CWT) recoveries by trip in recreational fisheries using Generalized Linear Models (GLMs). For the analysis, we incorporated as model predictors the area, month, year, and source of CWT recovery, which included reports by charterboat captains, creel-clerk interviews of non-charter anglers, and “headhunter” (CWT collection specialist) samples from charter and non-charter catch. Results indicated that CWT recoveries by trip were lowest from charterboat operators, followed by recoveries from creel clerks (2× captain reports), headhunter non-charter (3×), and headhunter charter (9×). Standardized recovery levels were highest in the management area of release and one area immediately adjacent, with remaining percentages decreasing with distance from release. CWT recovery levels decreased from May to September and suggest seasonal movement among areas that have implications for stock assessment. From standardized recoveries, we estimated that 40% of the CWT lake trout were recaptured in areas where released and others moved north, south, and southeast. Our results indicate that higher proportions of lake trout move out of release areas fish than previously shown and suggest that prior studies may be biased, in part due to lack of standardization among tag recovery sources and ignoring seasonal movements.

The Laurentian Great Lakes of North America have horizontal scales of hundreds of kilometers and depth scales of hundreds of meters. In terms of coastal dynamics, they behave much like inland seas and exhibit physical processes characteristic of the coastal oceans. The lakes are dynamically similar to the coastal ocean in that their horizontal dimensions are larger than the vertical dimensions, and the principal source of mechanical energy is the wind. The major difference in dynamical processes is that the lakes are enclosed basins and are not connected to the deep ocean. This paper presents an overview of some of the significant aspects of physical processes in the coastal zones of the Great Lakes. The review is based on examples ranging from lake-wide experiments like the International Field Year on the Great Lakes (IFYGL) to several process-oriented coastal boundary layer experiments. The basic circulations in the nearshore zone and coastal boundary layer are summarized. The review concludes with suggestions for future work on the understanding of the physical processes that would have a bearing on lake management in the coastal zones of the Great Lakes.

Sediment-water interface nitrogen (N) transformations and water column ammonium cycling rates were measured along a stream to lake gradient at three sites within Old Woman Creek (OWC) and one near-shore Lake Erie site during two hydrological regimes: one with open flow to the lake after a rain event (July 2003), and another with a sand barrier blocking flow (July 2004). Net N₂ effluxes in OWC at all times and at the near-shore Lake Erie site in July 2003 suggest that sediments are a N sink via denitrification. Observed dissimilatory nitrate reduction to ammonium (DNRA) may counteract some of this N removal, particularly when the creek mouth is closed. Upstream, a closed creek mouth led to higher sediment oxygen demand, net N₂ flux, potential DNRA, and potential denitrification rates. The lake site exhibited lower rates of these processes with the creek mouth closed except denitrification potential, which was unchanged. Denitrification in OWC appeared to drive N limitation in the lower wet-land when the sand barrier was blocking flow to the lake. Higher potential versus in situ denitrification estimates imply that water column NO₃⁻ limits and drives denitrification in OWC. Water column to sediment regeneration ratios suggest that sediment recycling may drive primary production in the OWC interior when the creek mouth is closed and new N inputs from runoff are absent, but more data are needed to confirm these apparent trends. Overall, hydrological regime in OWC appeared to have a greater impact on sediment N processes than on water column cycling.

A 3D transport model is used to perform a comparative analysis of several potential drinking water intakes located along the northwest shore of Lake Ontario between Toronto and Oshawa. The model is specifically used to assess each intake under both long- and short-term transport of a potential pollutant release from the Pickering Nuclear Generating Station and potential and actual pollutant releases from local land sources respectively. A model based on a 500 m grid resolution is calibrated using data collected in the aftermath of the 1992 tritium spill at the Pickering Nuclear Generation Station and subsequently used to simulate long-term transport. A model based on a 100 m grid resolution is verified using drogue studies and used to simulate short-term transport events. Both models are used to assess pollutant levels at each of nine potential intake locations under different wind scenarios and pollutant releases. Field data for the study included water quality and flow measurements from local sewers and rivers, and estimates of pollutant levels from the local waste water treatment plants. This paper describes the model setup for both the long-term and short-term transport models, calibration using field data, long-term transport modeling, short-term transport modeling, and the comprehensive analysis approach used to evaluate the nine potential intake locations proposed. Results indicated that four intakes in particular outperformed other intake locations by maintaining bottom pollutant levels within governmental standards and warning times that exceeded 20 hours.

Monitoring health indicators of fish populations can be an expensive and time consuming process. This study analyzed energy dynamics of Lake Michigan Chinook salmon using proximate composition analysis with the goal of determining an efficient method for monitoring the nutritional status of the population. Condition factor performed poorly as an indicator of whole-fish lipids (r² = 0.07). Water content in a dorsal muscle plug was found to be correlated with whole-fish lipids (r² = 0.50) for all samples. For the subset of samples that included small fish collected in the spring, the strength of the relationship between water content in a dorsal muscle plug and whole-fish lipids increased (r² = 0.70). The metric of water content in a dorsal muscle plug was determined to provide an adequate surrogate of whole-fish lipid content and, therefore, overall nutritional status. We propose a monitoring program that involves collecting small individuals in the spring and reporting the proportion of samples with over 78% water content in muscle tissue. Small individuals collected in the spring had the lowest whole-fish lipid levels of any segment of the population and would be the most prone to nutritional stress; therefore we recommend focusing on them for monitoring.

Shorelines of Lake Algonquin, the largest of the glacial lakes of the Great Lakes area, are well known in southern Ontario, but are sporadic and difficult to trace northward onto the Precambrian shield. Improved knowledge of the extent and uplift pattern for Algonquin shorelines is needed to support geophysical models of isostatic response, interpretation of glacial and glacial lake history, and the search by archeologists for evidence of Paleoindian activity, shown to be localized along its shoreline. The Sudbury basin is one of the few areas of mapping of Quaternary geology on the Canadian shield that provides a record of Algonquin lake phases. Meltwaters from the northward-receding ice front formed a series of deltas southward into the Sudbury basin in central Ontario around the time the Cartier I moraine was deposited. Instrumental surveys of deltas, bars, and shorebluffs carried out in the northern Sudbury basin delineate several discrete water planes. Correlation with previously surveyed and correlated shorelines on Manitoulin Island, southwest of Sudbury, indicates the presence of an upper Algonquin shoreline and features correlated to the Cedar Point, Payette, Sheguiandah, and Korah levels. Features southwest of the Sudbury basin at Nairn correlate with Korah and post-Korah water levels. Land between Nairn and Sudbury is too elevated to have been reached by the later Nipissing transgression. Similar shoreline sequences have been surveyed near North Bay, with results supporting the findings of this study.

The objective of this study was to measure the in situ spectral reflectance of lake water that contains a bloom of Microcystis, a species of cyanobacteria. Reflectance spectra (350–2,500 nm) of lake water near a boat dock in Upper Klamath Lake, Oregon, were collected with a portable spectrora-diometer on a cloud-free day with sunlight as a source of illumination between 0845 to 0915 hours, Pacific Daylight Time (PDT) on 17 August 2004, at a near-normal angle of observation. The averaged spectrum of the lake water containing the Microcystis bloom exhibits reflectance maxima from 550–590 nm and near 710 nm wavelengths and reflectance minima near 630 nm and 675 nm wavelengths. The reflectance gradually decreases from 810–1,000 nm and has very low reflectance in the 1,000–2,500 nm wavelength region. Our results show that the spectral reflectance of Microcystis at this stage of its bloom remains low for wavelengths longer than 1,000 nm in the near-infrared region of the spectrum. These spectral results have implications in selecting the spectral ratios and refining the algorithms that will be used to estimate phycocyanin content using satellite models. Microcystis is the predominant species of cyanobacteria blooms in Lake Erie, which makes these spectral data as important to the Great Lakes as it is to Upper Klamath Lake. Satellite algorithms have been published that have mapped phycocyanin, a pigment more uniquely associated with cyanobacteria than is chlorophyll a, in Lake Erie with data from LANDSAT TM bands 1, 3, 4, 5, and 7, and the reflectance spectra reported here are the first that cover the entire spectral range of all those LANDSAT TM spectral bands for a Microcystis bloom.

Hemimysis anomala G.O. Sars, 1907, a mysid species native to the Ponto-Caspian region, was discovered during fall 2006 in the Lake Michigan basin. Large numbers of individuals formed aggregations (averaging 1,540 ± 333 individuals/m²) in a shallow docking basin connected to the channel linking Lake Michigan and Muskegon Lake. The population included females (63%), males (35%), and juveniles (2%). The global invasion pattern in H. anomala is similar to that in another Ponto-Caspian peracarid crustacean, Echinogammarus ischnus. As with E. ischnus, the expansion of H. anomala in North America is anticipated.