Cooperative Institute for Great Lakes Research

Abstract. Results of a lake model intercomparison study conducted within the framework of Lake Model Intercomparison Project are presented. The investigated lake was Großer Kossenblatter See (Germany) as a representative of shallow, (2 m mean depth) turbid midlatitude lakes. Meteorological measurements, including turbulent fluxes and water temperature, were carried out by the Lindenberg Meteorological Observatory of the German Meteorological Service (Deutscher Wetterdienst, DWD). Eight lake models of different complexity were run, forced by identical meteorological variables and model parameters unified as far as possible given different formulations of processes. All models generally captured diurnal and seasonal variability of lake surface temperature reasonably well. However, some models were incapable of realistically reproducing temperature stratification in summer. Total heat turbulent fluxes, computed by the surface flux schemes of the compared lake models, deviated on average from those measured by eddy covariance by 17–28 W m−2. There are a number of possible reasons for these deviations, and the conclusion is drawn that underestimation of real fluxes by the eddy covariance technique is the most probable reason. It is supported by the fact that the eddy covariance fluxes do not allow to close the heat balance of the water column, the residual for the whole period considered being ≈–28 W m−2. The effect of heat flux to bottom sediments can become significant for bottom temperatures. It also has profound influence on the surface temperatures in autumn due to convective mixing but not in summer when the lake stratification is stable. Thus, neglecting sediments shifts the summer–autumn temperature difference in models lacking explicit treatment of sediments considerably. As a practical recommendation based on results of the present study, we also infer that in order to realistically represent lakes in numerical weather prediction and climate models, it is advisable to use depth-resolving turbulence models (or equivalent) in favor of models with a completely mixed temperature profile.

A major episodic sediment resuspension event (25‐yr high), which was triggered by atmospheric and water column instability in an El Niň;o year, temporarily altered the dynamics of autotrophy and heterotrophy in Lake Michigan. Resuspended sediments, rich in organic and inorganic nutrients, especially phosphorus, stimulated heterotrophic production despite low water temperatures (2ºC or less). During the resuspension event, southern basin winter heterotrophic bacterial productivity was high (64% of summertime productivity), especially along the margins of the lake. The mean bacterial cell size increased in regions where productivity was highest during the resuspension event. Although resuspended sediments stimulated bacterial secondary productivity, they simultaneously decreased water‐column light availability and autotroph biomass. Consequently, heterotrophic bacteria were temporally decoupled from the commonly recognized source of organic matter for bacterial production—photoautotrophy. Variation in the magnitude and frequency of these resuspension events likely influences variation in interannual productivity in this system. Such previously underappreciated, intermittent, and ephemeral benthic‐pelagic exchange events may significantly influence plankton dynamics and biogeochemical cycling in coastal marine and freshwater ecosystems.

Hydrogen peroxide (H2O2) has been suggested to influence cyanobacterial community structure and toxicity. However, no study has investigated H2O2 concentrations in freshwaters relative to cyanobacterial blooms when sources and sinks of H2O2 may be highly variable. For example, photochemical production of H2O2 from chromophoric dissolved organic matter (CDOM) may vary over the course of the bloom with changing CDOM and UV light in the water column, while microbial sources and sinks of H2O2 may change with community biomass and composition. To assess relationships between H2O2 and harmful algal blooms dominated by toxic cyanobacteria in the western basin of Lake Erie, we measured H2O2 weekly at six stations from June – November, 2014 and 2015, with supporting physical, chemical, and biological water quality data. Nine additional stations across the western, eastern, and central basins of Lake Erie were sampled during August and October, 2015. CDOM sources were quantified from the fluorescence fraction of CDOM using parallel factor analysis (PARAFAC). CDOM concentration and source were significantly correlated with specific conductivity, demonstrating that discharge of terrestrially-derived CDOM from rivers can be tracked in the lake. Autochthonous sources of CDOM in the lake increased over the course of the blooms. Concentrations of H2O2 in Lake Erie ranged from 47 ± 16 nM to 1570 ± 16 nM (average of 371 ± 17 nM; n = 225), and were not correlated to CDOM concentration or source, UV light, or estimates of photochemical production of H2O2 by CDOM. Temporal patterns in H2O2 were more closely aligned with bloom dynamics in the lake. In 2014 and 2015, maximum concentrations of H2O2 were observed prior to peak water column respiration and chlorophyll a, coinciding with the onset of the widespread Microcystis blooms in late July. The spatial and temporal patterns in H2O2 concentrations suggested that production and decay of H2O2 from aquatic microorganisms can be greater than photochemical production of H2O2 from CDOM and abiotic decay pathways. Our study measured H2O2 concentrations in the range where physiological impacts on cyanobacteria have been reported, suggesting that H2O2 could influence the structure and function of cyanobacterial communities in Lake Erie.

Abstract We applied a three‐dimensional biophysical model to Lake Michigan for the years 2000, 2005, and 2010 to consider the mechanisms controlling spatial and temporal patterns of phytoplankton abundance (chlorophyll a ) and lake‐wide productivity. Model skill was assessed by comparison to satellite‐derived Chl a and field‐measured water quality variables. We evaluated model sensitivity to scenarios of varying mussel filter feeding intensity, tributary phosphorus loads, and warm vs. cool winter‐spring climate scenarios. During the winter‐spring phytoplankton bloom, spatial patterns of Chl a were controlled by variables that influenced surface mixed layer depth: deep mixing reduced net phytoplankton growth through light limitation and by exposing the full water column to mussel filter feeding. Onset of summer and winter stratification promoted higher surface Chl a initially by increasing mean light exposure and by separating the euphotic zone from mussels. During the summer stratified period, areas of relatively high Chl a were associated with coastal plumes influenced by tributary‐derived nutrients and coastal upwelling‐downwelling. While mussels influenced spatial and temporal distribution of Chl a , lake‐wide, annual mean primary production was more sensitive to phosphorus and warm/cool meteorology scenarios than to mussel filter feeding scenarios. Although Chl a and primary production declined over the quagga mussel invasion, our results suggest that increased nutrient loads would increase lake‐wide productivity even in the presence of mussels; however, altered spatial and temporal patterns of productivity caused by mussel filter feeding would likely persist.

Abstract Hypoxia, defined as dissolved oxygen (DO) < 2 mg/L, in the central basin of Lake Erie has been studied since the mid‐1900s. Even so, spatial patterns of hypoxia, and episodic hypoxia in nearshore areas where drinking water plant intakes are located, are not well characterized owing to limited observations and short‐term dynamics. We evaluated a physically based, DO model with respect to patterns of hypoxia observed in Lake Erie. The DO model used assigned rates of sediment and water column oxygen demand that were temperature dependent but otherwise spatially and temporally uniform. The DO model was linked to National Oceanic and Atmospheric Administration's (NOAA) Lake Erie Operational Forecasting System hydrodynamic model, an application of the Finite Volume Community Ocean Model (FVCOM). Model temperature and DO were compared with observations from ship‐based studies, real‐time sensor networks and an array of moored sensors that we deployed in 2017. In years with dominant southwesterly winds, persistent downwelling occurred along the south shore, which resulted in a thinner thermocline and earlier initiation of hypoxia along the south shore than the north. Occasional northeast winds temporarily reversed this pattern, causing upwelling along the south shore that brought hypoxic water to nearshore locations and water intakes. The DO model reproduced observed spatial and temporal patterns of hypoxia and revealed locations subject to episodes of hypoxia, including nearshore Ohio, north of Pelee Island, and near the Bass Islands. Model skill was limited in some respects, highlighting the importance of accurate simulation of the thermal structure and spatial patterns of oxygen demand rates.

The plume structure of Perdido Bay Estuary (PBE), a typical bay on the Florida-Alabama coast along the Gulf of Mexico, was simulated using an existing calibrated model. To better understand plume dynamics in the PBE and similar bay systems, idealized sensitivity experiments were conducted to examine the influence of wind stress on the 3-D plume signature: the results indicate that wind speed and direction significantly influence plume orientation, area, width, length, and depth. The plume size was reduced under the effect of wind and increased wind forcing. Among wind-forced cases, the plume is largest for northerly (offshore) winds and smallest for southerly (onshore) winds. Bay-shelf salt flux and water flux were also investigated, since they are important for the formation of a 3-D plume structure. Model simulations show that water outflow to the coastal ocean is strongest under northerly winds and can be stopped by southerly winds. For moderately strong winds, the outflow and plume size are larger for easterly downwelling-favorable winds than for westerly upwelling-favorable winds; the opposite is true for outflow and plume size for these two wind directions under stronger winds. For all wind directions, the ratio of salt flux and water flux at the bay mouth increases with wind speed. This ratio trend is consistent with higher outflow salinities, and this decreased buoyancy signature, along with more energetic vertical mixing, reduces plume size. A detailed understanding of this water and salt flux is essential to the plume dynamics studied here and for other plumes. Additional particle transport analysis using variable wind forcing was conducted to determine the influence of the plume on particle movement. The results showed a consistency between the surface plume, salt flux, and particle transport and illustrate the strong effects that winds have on particle fate and dispersion.

NOAA GLERL has routinely flown a hyperspectral imager to detect cyanobacteria harmful algal blooms (cyanoHABs) over the Great Lakes since 2015. Three consecutive years of hyperspectral imagery over the Great Lakes warn drinking water intake managers of the presence of cyanoHABs. Western basin imagery of Lake Erie contributes to a weekly report to the Ohio Environmental Protection Agency using the cyanobacteria index (CI) as an indicator of the presence of cyanoHABs. The CI is also used for the weekly NOAA NCCOS cyanoHAB Lake Erie bulletin applied to satellite data. To date, there has not been a sensor comparison to look at the variability between the satellite and hyperspectral imagery on a pixel-by-pixel basis, as well as a time scale comparison between measurements from buoys and shipboard surveys. The spatial scale is a measure of size of a cyanobacteria bloom on a scale of meters to kilometers. The change in the spatial scale or spatial variability has been quantified from satellite and airborne imagery using a decorrelation scale analysis to find the point at which the values are not changing or are not correlated with each other. The decorrelation scales were also applied to the buoy and shipboard survey data to look at temporal scales or changes in time on hourly to daytime scales for blue-green algae, chlorophyll and temperature. These scales are valuable for ecosystem modelers and for those initiating sampling efforts to optimize sampling plans and to infer a potential mechanism in an observational study from a synoptic viewpoint.

Concentrations of dissolved and particulate nutrients, chlorophyll, and microorganisms (0.01 to 200 pm) were simultaneously measured during a 1 d survey of 12 stations in Florida Bay, USA, to characterize the microbial plankton community with respect to resource limitation. Three distinct types of trophic conditions, reflected in seston elemental stoichiometry and community structure, were identified within the bay. The first type, characteristic of the isolated eastern region, had low nutrient concentrations, imbalanced stoichiometry, and small microbial biomass with a large proportion of bacteria. The microbial community in this region was characterized by weak relationships between microzooplankton and phytoplankton and the predominance of mixotrophic taxa and the autotrophic ciliate Mesodinjum rubrum. The second type, found in the north-central region influenced by Taylor Slough ~nflow, had elevated nutrient concentrations, elemental stoichiometry skewed toward N , and high turbidity. Under these conditions, the p~cocyanobactenum Synechococcus formed a dense bloom and coincided with an abundant, multi-step microbial food web. Finally, at the boundary with the Gulf of Mexico, low concentrations of nutrients were balanced at approximately the Redfield ratio and supported nanophytoplankton that were tightly correlated with microzooplankton. These data are consistent with the notion of P Imitation in Florida Bay but also demonstrate that Si, light, and N may be colimiting to phytoplankton In the eastern, north-central, and western boundary regions, respectively. Our findings suggest that multiple resource gradients, in conjunction with microbial food web processes, are important factors determining the plankton community structure in Florida Bay and should be considered in studies on ecological disturbances.

The benthic macroinvertebrate community of Lake Ontario was assessed through a lakewide survey in 2008. Diporeia was very rare throughout the lake at all depths in 2008, and only four of 52 locations had densities >100 m−2, all of them at depths >90 m. The maximum density of Diporeia found at any location was at 257 m−2 in 2008, which can be compared to maximum densities of 13,280 m−2 observed in 1994. Lakewide Diporeia abundance declined with an additional order of magnitude from an average of 342 m−2 in 2003 to 21 m−2 in 2008. The Quagga Mussel (D. rostriformis bugensis) dominated the benthic macroinvertebrate community in 2008, comprising over 70% of the density and 98% of the biomass. No Zebra Mussels were identified in the 2008 samples. Quagga Mussels, Oligochaetes and Chironomids were most abundant between 31 and 90 m. Sphaeriids were rare at all depths, but were more abundant at sites deeper than 90 m. Between 2003 and 2008, lakewide Dreissena abundance declined by 43% primarily due to significant declines in the 10–30 m depth region (from 6500 m−2 to 900 m−2). Dreissena did not decline significantly in the 30–90 m or over 90 m depth regions. The 2008 survey revealed a continued decline in Diporeia and Sphaeriid Clams, a replacement of Zebra Mussels by Quagga Mussels, and a decline in Quagga Mussels at depths shallower than 30 m. Oligochaetes and chironomids showed no significant changes since the 1990s.

Environmental fluid dynamic code (EFDC), a numerical estuarine and coastal ocean circulation hydrodynamic model, was used to simulate the distribution of the salinity, temperature, nutrients, and dissolved oxygen (DO) in Perdido Bay and adjacent Gulf of Mexico. External forcing factors included the coupled effects of the astronomical tides, river discharge, and atmospheric winds on the spatial and temporal distributions of salinity and DO. Modeled time series were in good agreement with field observations of water level, nutrients, temperature, salinity, and DO. Perdido Bay and adjacent northern Gulf of Mexico coasts can be divided into two areas according to salinity, water level, and DO concentrations. The first area was lower Perdido Bay and the associated Gulf of Mexico coasts, acting primarily under the influence of tidal forcing, which increases the vertical stratification. The second division was upper Perdido Bay, which was influenced by both tidal forcing and freshwater inflow. Simulations also indicated winds influenced the salinity and DO distributions, with an enhanced surface pressure gradient. Tidal effects were also important for conducting salinity and water quality simulations in Perdido Bay. Low amplitude tides induced relatively weak vertical mixing and favored the establishment of stratification at the bay, especially along deeper bathymetry. Flood tides influenced the distribution of salinity and DO more than ebb tides, specifically along shallow bathymetry.

This study assessed the distribution, abundance, and viability of pre- and post-overwintering Microcystis sediment seed stocks in Western Lake Erie and how these variables are potentially related to past and subsequent bloom formation. We conducted a two-year spatiotemporal survey of vegetative seed stocks in Western Lake Erie, the region where annual algal blooms generally develop. Sediment was collected from 16 sites covering an area of 375 km2 and water column depths ranging from 3-9 meters. Sample collection occurred in November 2014, April 2015, November 2015, and April 2016. The abundance of total and potentially-toxic Microcystis cell equivalents were determined using quantitative polymerase chain reaction. A series of laboratory experiments using lake sediment were conducted to assess the viability of Microcystis vegetative seed stocks. Across all sampling periods, the abundance of total Microcystis in the sediment ranged from 6.6 x 10(4) to 1.7 x 10(9) cell equivalents g-1, and potentially-toxic Microcystis ranged from 1.4 x 10(3) to 4.7 x 10(6) cell equivalents g-1. The percent potentially-toxic Microcystis in the sediment ranged from <1% to 68% across all samples. Total Microcystis abundance diminished significantly over winter with densities in spring nearly 10 times less than the previous fall. However, despite cell loss from fall to spring, lab experiments demonstrated that remaining non-toxic and potentially-toxic cells were viable after the overwintering period. Further, lab grow-out experiments indicate that potentially-toxic strains recruited at a slightly higher rate than non-toxic strains, and may in part, contribute to the pattern of higher relative toxicity during early stages of the blooms. The abundance and distribution of overwintering cells did not correlate strongly to areas in the lake where subsequent summer blooms were most persistent. However, numerical analysis suggests that recruitment of benthic overwintering populations could help explain a portion of the initial rapid increase in bloom biomass and the spatial extent of this bloom initiation, particularly when recruitment is paired with subsequent growth in appropriate water column conditions.

Instrumented moorings were deployed during the winter of 1994–95 at three depths (28, 58 and 101 m) in southern Lake Michigan. Storms during the observation period were not unusually severe, so the processes observed are typical of those that occur during an average winter. Time series observations of water temperature, beam attenuation coefficient (a measure of water transparency) and current velocity show that local resuspension of bottom sediment occurred frequently after the breakdown of the thermocline. Resuspension was most frequent close to the shore but was also observed at the 58 m station. Local resuspension did not occur at the 101 m station, but advection to the site of material resuspended at shallower sites was observed. These observations do not support the hypothesis proposed by previous investigators that local resuspension at depths of 100 m or greater occurs during the unstratified period. It is more likely that fine‐grained material resuspended by storm action in intermediate water depths (≈ 30–60 m) is transported into the deeper parts of the lake by the general lake circulation.

Abstract Climate change due to anthropogenic greenhouse gases (GHG) is expected to have important impacts on water resources, with a variety of societal impacts. Recent research has shown that applying different methodologies to assess hydrologic impacts can lead to widely diverging projections of water resources. The authors classify methods of projecting hydrologic impacts of climate change into those that estimate potential evapotranspiration (PET) based on air temperature and those that estimate PET based on components of the surface energy budget. In general, air temperature–based methods more frequently show reductions in measures of water resources (e.g., water yield or soil moisture) and greater sensitivity than those using energy budget–based methods. There are significant trade-offs between these two methods in terms of ease of use, input data required, applicability to specific locales, and adherence to fundamental physical constraints: namely, conservation of energy at the surface. Issues of uncertainty in climate projections, stemming from imperfectly known future atmospheric GHG concentrations and disagreement in projections of the resultant climate, are compounded by questions of methodology and input data availability for models that connect climate change to accompanying changes in hydrology. In the joint atmospheric–hydrologic research community investigating climate change, methods need to be developed in which the energy and moisture budgets remain consistent when considering their interaction with both the atmosphere and water resources. This approach should yield better results for both atmospheric and hydrologic processes.

As part of the Episodic Events Great Lakes Experiment, we sampled total suspended matter (TSM), light climate, nutrients, and plankton along cross‐margin transects in southern Lake Michigan during February, March, and April 1998–2000 to capture conditions before, during, and after the occurrence of storm‐driven recurrent coastal sediment plumes to define the anatomy of the resuspension events and get insights into their interactions with nutrients and plankton. Variability in timing and strength of winter storms among years led to different timing, intensity, and extent of plumes among years. TSM concentrations in the core of plumes varied between 15 and 30 mg L −1 , and photic depth was reduced to ∼1 to 2 m, thus potentially seriously limiting phytoplankton growth in plume areas. Total P concentration was highly correlated with TSM and river influence. Chlorophyll concentrations were lower in plume regions than in adjacent areas, in contrast to the relatively constant chlorophyll concentration across the plume predicted by a coupled hydrodynamic and nutrient‐phytoplankton‐zooplankton model. Contrary to expectation, protozoan microzooplankton (MZ) biomass was not more abundant in the plume than adjacent waters, but was highest in nearshore areas receiving river inflow. Storms affected horizontal distribution of zooplankton. Because of the lower concentrations of phytoplankton in the plume, the plume over the short term had a negative impact on zooplankton during this food‐limiting season. Our results combined with those of other EEGLE studies lead us to conclude that storms and storm‐driven plumes had a negative effect on the planktonic food web.

Abstract Lake stratification produces sharp gradients in temperature and pelagic resources which have cascading effects on the traits of aquatic populations, including invasive species and their ecosystem impacts. We study the consequences of such common environmental gradients on the demography of quagga mussels, one of the world's most aggressive invasive species. Coupling a series of in situ experiments with a biophysical model of the pelagic community, we quantify mussel growth and recruitment in littoral vs. profundal benthic habitats of eastern Lake Erie. We found that both severe food depletion and cold temperatures in the hypolimnion during summer stratification cause mussels to grow twice as slowly and currently inhibit recruitment in profundal compared to littoral habitats. Together with the high biomass and large mean mussel size found in long‐term monitoring surveys in the profundal habitats, our results imply that mussels successfully colonizing profundal habitats have relatively long lifespans with low growth rates, and therefore lower productivity, compared to mussels in shallow areas. Consequently, the bulk of dreissenid biomass in Lake Erie and other Great Lakes found in the vast but resource‐poor profundal habitats may have very limited impacts on epilimnetic communities compared to mussels in littoral areas. By contrast, mussels in profundal habitats strongly reduce food availability to hypolimnetic communities throughout the year. Thus, our results explain how the ecosystem impacts of sessile freshwater invaders are likely to vary among habitats and lakes depending on the relative size of profundal populations and the extent of stratification.

Abstract. Turbulent fluxes of latent and sensible heat are important physical processes that influence the energy and water budgets of the North American Great Lakes. These fluxes can be measured in situ using eddy covariance techniques and are regularly included as a component of lake–atmosphere models. To help ensure accurate projections of lake temperature, circulation, and regional meteorology, we validated the output of five algorithms used in three popular models to calculate surface heat fluxes: the Finite Volume Community Ocean Model (FVCOM, with three different options for heat flux algorithm), the Weather Research and Forecasting (WRF) model, and the Large Lake Thermodynamic Model. These models are used in research and operational environments and concentrate on different aspects of the Great Lakes' physical system. We isolated only the code for the heat flux algorithms from each model and drove them using meteorological data from four over-lake stations within the Great Lakes Evaporation Network (GLEN), where eddy covariance measurements were also made, enabling co-located comparison. All algorithms reasonably reproduced the seasonal cycle of the turbulent heat fluxes, but all of the algorithms except for the Coupled Ocean–Atmosphere Response Experiment (COARE) algorithm showed notable overestimation of the fluxes in fall and winter. Overall, COARE had the best agreement with eddy covariance measurements. The four algorithms other than COARE were altered by updating the parameterization of roughness length scales for air temperature and humidity to match those used in COARE, yielding improved agreement between modeled and observed sensible and latent heat fluxes.

Isotope ratios for ammonium were determined directly on seawater filtrates by high performance liquid chromatography (HPLC) for isotope dilution and enrichment experiments in the Mississippi River plume region of the Gulf of Mexico. The 2 isotopic forms could be differentiated by cation exchange chromatography because the ratio of "NH,': "NH, is slightly greater than the ratio of 14NH,+: I4NH3 in aqueous solutions at pH's near the pK for ammonium (ca pH 9). Relatively small (e.g. 60 ml) water samples were fortified in the field with lSN-ammonium or "N-amino acids and incubated at simulated in situ temperature and light conditions. At 2 to 13 h intervals, subsamples were filtered (0.2 pm pore size) and frozen for later HPLC analysis in the laboratory. Isotope-dilution experiments conducted on water samples collected from different depths in the plume indicated that maximum ammonium regeneration rates occurred in near-surface waters where phytoplankton and bacterial production rates are relatively high. Amino acid and ammonium concentration changes and ISN-NH, compositional changes were measured at 4 intervals over 21 h after the addition of a n I5N-labeled amino acid mixture (4 FM). Comparison of the amount of 15N recovered as I5NH, to that removed from solution as 15N-labeled amino acids indicated that the potential conversion of 'assimilated' "N-labeled amino acids to dissolved ammonium ranged from about 50 % in surface water to about 90 % in nearbottom (30 m depth) water. These results demonstrate the usefulness of the HPLC approach for measuring nitrogen regeneration rates or conversion efficiencies in small volumes of marine coastal waters.

Summary Diatoms are among the few eukaryotes known to store nitrate (NO 3 − ) and to use it as an electron acceptor for respiration in the absence of light and O 2 . Using microscopy and 15 N stable isotope incubations, we studied the relationship between dissimilatory nitrate/nitrite reduction to ammonium (DNRA) and diel vertical migration of diatoms in phototrophic microbial mats and the underlying sediment of a sinkhole in Lake Huron (USA). We found that the diatoms rapidly accumulated NO 3 − at the mat‐water interface in the afternoon and 40% of the population migrated deep into the sediment, where they were exposed to dark and anoxic conditions for ~75% of the day. The vertical distribution of DNRA rates and diatom abundance maxima coincided, suggesting that DNRA was the main energy generating metabolism of the diatom population. We conclude that the illuminated redox‐dynamic ecosystem selects for migratory diatoms that can store nitrate for respiration in the absence of light. A major implication of this study is that the dominance of DNRA over denitrification is not explained by kinetics or thermodynamics. Rather, the dynamic conditions select for migratory diatoms that perform DNRA and can outcompete sessile denitrifiers.

ReCON, a coastal observation network with nodes on Lakes Michigan, Huron, and Erie, has been designed to allow flexible deployment of coastal access points and simplified integration of sensor packages. The system provides continuous observations of chemical, biological, and physical parameters, facilitates modification of sampling parameters in anticipation of episodic events, facilitates collection of field samples in response to episodic events, supports long term research and contributes to sensor and system development. The system currently supports projects addressing harmful algal bloom (HAB) detection, human health observations related to beach closures and drinking water processing concerns, rip current warnings, integrated ecosystem assessment, and public access to historic shipwrecks at the Thunder Bay National Marine Sanctuary. ReCON system development relies on wireless broadband technology and a network-based underwater hub designed to allow expansion via satellite nodes. The system architecture allows simplified integration of sensors from various institutions through guest ports. Access to and control of instrumentation is made available to the scientific community and educational institutions through the internet. A real-time database management system provides data and information for forecast model initial conditions, forecast verification, public information, and educational outreach. The technology demonstrated on the ReCON project represents an important contribution to the success of regional coastal ocean observing systems. The pervasiveness of wireless internet technology in coastal regions represents an opportunity to significantly expand high bandwidth coastal observation capabilities. Implementing ReCON on a regional coastal level in the Great Lakes has contributed to better tools and understanding for managers and educators, more on-water observations for marine forecasters, and improved scientific measurements.

Algal biofuel has yet to realize its potential as a commercial and sustainable bioenergy source, largely due to the challenge of maximizing and sustaining biomass production with respect to energetic and material inputs in large-scale cultivation. Experimental studies have shown that multispecies algal polycultures can be designed to enhance biomass production, stability, and nutrient recycling compared to monocultures. Yet, it remains unclear whether these impacts of biodiversity make polycultures more sustainable than monocultures. Here, we present results of a comparative life cycle assessment (LCA) for algal biorefineries to compare the sustainability metrics of monocultures and polycultures of six fresh-water algal species. Our results showed that when algae were grown in outdoor experimental ponds, certain bicultures improved the energy return on investment (EROI) and greenhouse gas emissions (GHGs) by 20% and 16%, respectively, compared to the best monoculture. Bicultures outperformed monocultures by performing multiple functions simultaneously (e.g., improved stability, nutrient efficiency, biocrude characteristics), which outweighed the higher productivity attainable by a monoculture. Our results demonstrate that algal polycultures with optimized multifunctionality lead to enhanced life cycle metrics, highlighting the significant potential of ecological engineering for enabling future environmentally sustainable algal biorefineries.