2017 GLERL Publications with Abstracts

January 2017 - Present

ANDERSON, E.J., and D.J. Schwab. Meteorological influence on summertime baroclinic exchange in the Straits of Mackinac. Journal of Geophysical Research: Oceans 122(3):2171-2182 (DOI:10.1002/2016JC012255) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170011.pdf

Straits flows can impose a complex hydrodynamic environment with high seasonal variability and significant impacts to nearby water bodies. In the Straits of Mackinac, exchange flow between Lake Michigan and Lake Huron influences water quality and ecological processes, as well as the transport of any contaminants released in or near the straits. Although previous work has shown that a Helmholtz mode is responsible for the barotropic flow oscillations in the straits, baroclinic effects impose opposite surface and subsurface flows during the summer months. In this study, we use observations of currents and water temperatures from instruments deployed in the straits to validate a hydrodynamic model of the combined Lake Michigan-Huron system and then use the model results to investigate the baroclinic flow and determine the forcing mechanisms that drive exchange flow in the Straits of Mackinac. Analysis shows that although the Helmholtz mode drives a 3 day oscillation throughout the year, thermal stratification in the summer establishes a bidirectional flow that is governed by a shift from regional-scale to local-scale meteorological conditions. These results detail the seasonal variability in the straits, including the barotropic and baroclinic contributions to exchange flow and the influence of local atmospheric forcing on transport through the Straits of Mackinac.

BELETSKY, D., R. BELETSKY, E.S. RUTHERFORD, J.L. Sieracki, J.M. Bossenbroek, W.L. Chadderton, M.E. Wittmann, and D.M. Lodge. Predicting spread of aquatic invasive species by lake currents. Journal of Great Lakes Research 43(3):14-32 (DOI:10.1016/j.jglr.2017.02.001) (2017).

Knowledge of aquatic invasive species (AIS) dispersal is important to inform surveillance and management efforts to slow the spread of established invaders. We studied potential dispersal of invasive Eurasian ruffe Gymnocephalus cernua and golden mussel Limnoperna fortunei larvae in Lakes Michigan and Erie using a three-dimensional particle transport model. Ruffe is currently in Lake Superior and northern Lake Michigan, while Limnoperna has not yet invaded the Great Lakes. We predicted larval transport during several spawning seasons (individual years) from several major tributaries and ports that are most prone to invasion because of their significant recreational and commercial usage. Depending on release location, larvae traveled distances ranging from < 1 km to tens of kilometers (in some cases over 100–200 km, depending on species) during 2–3 weeks of drift time. Dispersal distances from nearshore locations (i.e. rivers and ports) were smaller than from offshore deballasting locations near ports. Limnoperna dispersal distances were larger than ruffe due to stronger seasonal currents and longer drift period. Settlement areas resulting from offshore releases were larger than for nearshore releases, and larger for Limnoperna than for ruffe. Model results compared favorably to observed spread of ruffe and Dreissena spp. mussels in Lake Michigan. Our modeling effort suggests that larval advection by lake currents is an important AIS dispersal mechanism in the Great Lakes. It also emphasizes the importance of effective surveillance programs that maximize early detection of new introductions before lake current dispersal obviates containment and prevention of spread and impacts.

Berry, M.A., T.W. DAVIS, R.M. Cory, M.B. Duhaime, T.H. JOHENGEN, C.L. Kling, J.A. Marino, P.A. Den Uyl, D.C. GOSSIAUX, G.J. Dick, and V.J. Denef. Cyanobacterial harmful algal blooms are a biological disturbance to western Lake Erie bacterial communities. Environmental Microbiology 19(Thematic Issue on Environmental Glycerol Metabolism ):1149-1162 (DOI:10.1111/1462-2920.13640) (2017).

Human activities are causing a global proliferation of cyanobacterial harmful algal blooms (CHABs), yet we have limited understanding of how these events affect freshwater bacterial communities. Using weekly data from western Lake Erie in 2014, we investigated how the cyanobacterial community varied over space and time, and whether the bloom affected non-cyanobacterial (nc-bacterial) diversity and composition. Cyanobacterial community composition fluctuated dynamically during the bloom, but was dominated by Microcystis and Synechococcus OTUs. The bloom's progression revealed potential impacts to nc-bacterial diversity. Nc-bacterial evenness displayed linear, unimodal, or no response to algal pigment levels, depending on the taxonomic group. In addition, the bloom coincided with a large shift in nc-bacterial community composition. These shifts could be partitioned into components predicted by pH, chlorophyll a, temperature, and water mass movements. Actinobacteria OTUs showed particularly strong correlations to bloom dynamics. AcI-C OTUs became more abundant, while acI-A and acI-B OTUs declined during the bloom, providing evidence of niche partitioning at the sub-clade level. Thus, our observations in western Lake Erie support a link between CHABs and disturbances to bacterial community diversity and composition. Additionally, the short recovery of many taxa after the bloom indicates that bacterial communities may exhibit resilience to CHABs.

Berry, M.A., J.D. White, T.W. DAVIS, S. Jain, T.H. JOHENGEN, G.J. Dick, O. Sarnelle, and V.J. Denef. Are oligotypes meaningful ecological and phylogenetic units? A case study of Microcystis in freshwater lakes. Frontiers in Microbiology 8:Article 365 (DOI:10.3389/fmicb.2017.00365 ) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170006.pdf

Oligotyping is a computational method used to increase the resolution of marker gene microbiome studies. Although oligotyping can distinguish highly similar sequence variants, the resulting units are not necessarily phylogenetically and ecologically informative due to limitations of the selected marker gene. In this perspective, we examine how oligotyping data is interpreted in recent literature, and we illustrate some of the method’s constraints with a case study of the harmful bloom-forming cyanobacterium Microcystis. We identified three Microcystis oligotypes from a western Lake Erie bacterial community 16S rRNA gene (V4 region) survey that had previously clustered into one OTU. We found the same three oligotypes and two additional sequence variants in 46 Microcystis cultures isolated from Michigan inland lakes spanning a trophic gradient. In Lake Erie, shifts in Microcystis oligotypes corresponded to spatial nutrient gradients and temporal transitions in bloom toxicity. In the cultures, Microcystis oligotypes showed preferential distributions for different trophic states, but genomic data revealed that the oligotypes identified in Lake Erie did not correspond to toxin gene presence. Thus, oligotypes could not be used for inferring toxic ecotypes. Most strikingly, Microcystis oligotypes were not monophyletic. Our study supports the utility of oligotyping for distinguishing sequence types along certain ecological features, while it stresses that 16S rRNA gene sequence types may not reflect ecologically or phylogenetically cohesive populations. Therefore, we recommend that studies employing oligotyping or related tools consider these caveats during data interpretation.

BOLINGER, R.A., A.D. GRONEWOLD, K.A. Kompoltowicz, and L.M. Fry. Application of the NMME in the Development of a New Regional Seasonal Climate Forecast Tool. Bulletin of the American Meteorological Society (DOI:10.1175/BAMS-D-15-00107.1) (2017).

The National Oceanic and Atmospheric Administration’s Climate Prediction Center (CPC) provides access to a suite of real-time monthly climate forecasts that compose the North American Multi-Model Ensemble (NMME) in an attempt to meet the increasing demands for monthly to seasonal climate prediction. While the North American and global map-based forecasts provided by CPC are informative on a broad or continental scale, operational and decision-making institutions need products with a much more specific regional focus. To address this need, we developed a Region-Specific Seasonal Climate Forecast (RSCF–NMME) tool by combining NMME forecasts with regional climatological data. The RSCF–NMME automatically downloads and archives data and is displayed via a dynamic web-based graphical user interface. The tool has been applied to the Great Lakes region and utilized as part of operational water-level forecasting procedures by the U.S. Army Corps of Engineers, Detroit District (USACE-Detroit). Evaluation of the tool, compared with seasonal climate forecasts released by CPC, shows that the tool can provide additional useful information to users and overcome some of the limitations of the CPC forecasts. The RSCF–NMME delivers details about a specific region’s climate, verification observations, and the ability to view different model forecasts. With its successful implementation within an operational environment, the tool has proven beneficial and thus set a precedent for expansion to other regions where there is a demand for region-specific seasonal climate forecasts.

Cable, R.N., D. BELETSKY, R. BELETSKY, B.W. Locke, K. Wigginton, and M.B. Duhaime. Distribution and modeled transport of plastic pollution in the Great Lakes, the world’s largest freshwater resource. Frontiers in Environmental Science (DOI:10.3389/fenvs.2017.00045) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170020.pdf

Most plastic pollution originates on land. As such, freshwater bodies serve as conduits for the transport of plastic litter to the ocean. Understanding the concentrations and fluxes of plastic litter in freshwater ecosystems is critical to our understanding of the global plastic litter budget and underpins the success of future management strategies. We conducted a replicated field survey of surface plastic concentrations in four lakes in the North American Great Lakes system, the largest contiguous freshwater system on the planet. We then modeled plastic transport to resolve spatial and temporal variability of plastic distribution in one of the Great Lakes, Lake Erie. Triplicate surface samples were collected at 38 stations in mid-summer of 2014. Plastic particles >106 µm in size were quantified. Concentrations were highest near populated urban areas and their water infrastructure. In the highest concentration trawl, nearly 2 million fragments km-2 were found in the Detroit River—dwarfing previous reports of Great Lakes plastic abundances by over 4-fold. Yet, the accuracy of single trawl counts was challenged: within-station plastic abundances varied 0- to 3-fold between replicate trawls. In the smallest size class (106-1000 µm), false positive rates of 12-24% were determined analytically for plastic versus non-plastic, while false negative rates averaged ~18%. Though predicted to form in summer by the existing Lake Erie circulation model, our transport model did not predict a permanent surface “Lake Erie Garbage Patch” in its central basin—a trend supported by field survey data. Rather, general eastward transport with recirculation in the major basins was predicted. Further, modeled plastic residence times were drastically influenced by plastic buoyancy. Neutrally buoyant plastics—those with the same density as the ambient water—were flushed several times slower than plastics floating at the water’s surface and exceeded the hydraulic residence time of the lake. It is likely that the ecosystem impacts of plastic litter persist in the Great Lakes longer than assumed based on lake flushing rates. This study furthers our understanding of plastic pollution in the Great Lakes, a model freshwater system to study the movement of plastic from anthropogenic sources to environmental sinks.

Collingsworth, P.D., D.B. Bunnell, M.W. Murray, Y.C. Kao, Z.S. Feiner, R.M. Claramunt, B.M. LOFGREN, T.O. Hook, and S.A. Ludsin. Climate change as a long-term stressor for the fisheries of the Laurentian Great Lakes of North America. Reviews in Fish Biology and Fisheries:1-29 (DOI:10.1007/s11160-017-9480-3) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170016.pdf

The Laurentian Great Lakes of North America provide valuable ecosystem services, including fisheries, to the surrounding population. Given the prevalence of other anthropogenic stressors that have historically affected the fisheries of the Great Lakes (e.g., eutrophication, invasive species, overfishing), climate change is often viewed as a long-term stressor and, subsequently, may not always be prioritized by managers and researchers. However, climate change has the potential to negatively affect fish and fisheries in the Great Lakes through its influence on habitat. In this paper, we (1) summarize projected changes in climate and fish habitat in the Great Lakes; (2) summarize fish responses to climate change in the Great Lakes; (3) describe key interactions between climate change and other stressors relevant to Great Lakes fish, and (4) summarize how climate change can be incorporated into fisheries management. In general, fish habitat is projected to be characterized by warmer temperatures throughout the water column, less ice cover, longer periods of stratification, and more frequent and widespread periods of bottom hypoxia in productive areas of the Great Lakes. Based solely on thermal habitat, fish populations theoretically could experience prolonged optimal growth environment within a changing climate, however, models that assess physical habitat influences at specific life stages convey a more complex picture. Looking at specific interactions with other stressors, climate change may exacerbate the negative impacts of both eutrophication and invasive species for fish habitat in the Great Lakes. Although expanding monitoring and research to consider climate change interactions with currently studied stressors, may offer managers the best opportunity to keep the valuable Great Lakes fisheries sustainable, this expansion is globally applicable for large lake ecosystem dealing with multiple stressors in the face of continued human-driven changes.

Denef, V.J., H.J. Carrick, J.F. CAVALETTO, E. Chiang, T.H. JOHENGEN, and H.A. VANDERPLOEG. Lake Bacterial Assemblage Composition Is Sensitive to Biological Disturbance Caused by an Invasive Filter Feeder. mSphere 2(3)(DOI:10.1128/mSphere.00189-17) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170015.pdf

One approach to improve forecasts of how global change will affect ecosystem processes is to better understand how anthropogenic disturbances alter bacterial assemblages that drive biogeochemical cycles. Species invasions are important contributors to global change, but their impacts on bacterial community ecology are rarely investigated. Here, we studied direct impacts of invasive dreissenid mussels (IDMs), one of many invasive filter feeders, on freshwater lake bacterioplankton. We demonstrated that direct effects of IDMs reduced bacterial abundance and altered assemblage composition by preferentially removing larger and particle-associated bacteria. While this increased the relative abundances of many free-living bacterial taxa, some were susceptible to filter feeding, in line with efficient removal of phytoplankton cells of <2 μm. This selective removal of particle-associated and larger bacteria by IDMs altered inferred bacterial functional group representation, defined by carbon and energy source utilization. Specifically, we inferred an increased relative abundance of chemoorganoheterotrophs predicted to be capable of rhodopsin-dependent energy generation. In contrast to the few previous studies that have focused on the longer-term combined direct and indirect effects of IDMs on bacterioplankton, our study showed that IDMs act directly as a biological disturbance to which freshwater bacterial assemblages are sensitive. The negative impacts on particle-associated bacteria, which have been shown to be more active than free-living bacteria, and the inferred shifts in functional group representation raise the possibility that IDMs may directly alter bacterially mediated ecosystem functions.

Dias, J.P., (and 44 others), and S.A. POTHOVEN. Establishment of a taxonomic and molecular reference collection to support the identification of species regulated by the Western Australian Prevention List for Introduced Marine Pests. Management of Biological Invasions 8(2):215-225 (DOI:10.3391/mbi.2017.8.2.09) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170030.pdf

Introduced Marine Pests (IMP, = non-indigenous marine species) prevention, early detection and risk-based management strategies have become the priority for biosecurity operations worldwide, in recognition of the fact that, once established, the effective management of marine pests can rapidly become cost prohibitive or impractical. In Western Australia (WA), biosecurity management is guided by the " Western Australian Prevention List for Introduced Marine Pests " which is a policy tool that details species or genera as being of high risk to the region. This list forms the basis of management efforts to prevent introduction of these species, monitoring efforts to detect them at an early stage, and rapid response should they be detected. It is therefore essential that the species listed can be rapid and confidently identified and discriminated from native species by a range of government and industry stakeholders. Recognising that identification of these species requires very specialist expertise which may be in short supply and not readily accessible in a regulatory environment, and the fact that much publicly available data is not verifiable or suitable for regulatory enforcement, the WA government commissioned the current project to collate a reference collection of these marine pest specimens. In this work, we thus established collaboration with researchers worldwide in order to source representative specimens of the species listed. Our main objective was to build a reference collection of taxonomically vouchered specimens and subsequently to generate species-specific DNA barcodes suited to supporting their future identification. To date, we were able to obtain specimens of 75 species (representative of all but four of the pests listed) which have been identified by experts and placed with the WA Government Department of Fisheries and, where possible, in accessible museums and institutions in Australasia. The reference collection supports the fast and reliable taxonomic and molecular identification of marine pests in WA and constitutes a valuable resource for training of stakeholders with interest in IMP recognition in Australia. The reference collection is also useful in supporting the development of a variety of DNA-based detection strategies such as real-time PCR and metabarcoding of complex environmental samples (e.g. biofouling communities). The Prevention List is under regular review to ensure its continued relevance and that it remains evidence and risk-based. Similarly, its associated reference collection also remains to some extent a work in progress. In recognition of this fact, this report seeks to provide details of this continually evolving information repository publicly available to the biosecurity management community worldwide.

Foley, C.J., S.R. Andree, S.A. POTHOVEN, T.F. NALEPA, and T.O. Hook. Quantifying the predatory effect of round goby on Saginaw Bay dreissenids. Journal of Great Lakes Research 43(1):121-131 (DOI:10.1016/j.jglr.2016.10.018) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170002.pdf

Invasive dreissenid mussels (D. polymorpha and D. r. bugensis) have fundamentally altered Laurentian Great Lake ecosystems, however in many areas their abundances have declined since the mid-1990s. Another invader, the benthic fish round goby (Neogobius melanostomus), is morphologically adapted to feed on dreissenids and likely affects dreissenid populations; however, the degree of this predatory effect is variable. In 2009 and 2010, we examined round goby abundances, size distributions, diet contents, and diet selectivity in Saginaw Bay, Lake Huron; a shallow bay that has been subjected to numerous anthropogenic stressors. We further used a consumption model to estimate dreissenid consumption by three different size classes of round goby. Round gobies were found throughout the bay and most were smaller than 80 mm total length. Round gobies of all sizes consumed dreissenids (including fish as small as 30 mm total length), though dreissenids were rarely preferred. The relative proportion of dreissenids (by biomass) present in diets of round gobies increased with fish size, but also throughout the year for all size classes. Despite this, overall consumptive effects of round gobies on dreissenids in Saginaw Bay were low. Many dreissenids present in the bay were larger than those consumed by round gobies. Bioenergetics-based model estimates suggest that the smallest round gobies are responsible for the majority of dreissenid consumption. While our findings are limited to soft substrates and influenced by sampling restrictions, our study design allowed us to put bounds on our estimates based upon these multiple sources of uncertainty.

Gaborit, E., V. Fortin, B. Tolson, L.M. FRY, T.S. HUNTER, and A.D. GRONEWOLD. Great Lakes Runoff Inter-comparison Project, phase 2: Lake Ontario (GRIP-O). Journal of Great Lakes Research 43(2):217-227 (DOI:10.1016/j.jglr.2016.10.004) (2017).

The Great Lakes Runoff Inter-comparison Project for Lake Ontario (GRIP-O) aims to compare different hydrologic models, using the same settings, in their ability to estimate runoff for the Lake Ontario watershed. The watershed is challenging because many of its tributaries have a regulated flow regime and a significant part remains ungauged. GRIP-O follows the GRIP-M project which focused on Lake Michigan. It involves a comparison between two different sources of precipitation data (CaPA - Canadian Precipitation Analysis and the GHCND - Global Historical Climatology Network - Daily), and focuses here on two lumped models, GR4J (modèle du Génie Rural à 4 paramètres Journalier) and LBRM (Large Basin Runoff Model).

Results indicate that both models perform very well, with GR4J performing slightly better than LBRM and the GHCND precipitation dataset resulting in better simulations than CaPA, for this area. Performances are, however, always very satisfactory whatever the combination of model/precipitation data used, even for regulated catchments, and do not show any clear correlation to any of the catchments' properties studied here. Results also tend to confirm that the Area-Ratio Method is appropriate for extrapolating flows from the gauged part of a catchment to the whole catchment including its ungauged parts, as demonstrated in GRIP-M.

Gaborit, E., V. Fortin, A. Xu, F. Seglenieks, B. Tolson, L.M. Fry, T.S. HUNTER, F. Anctil, and A.D. GRONEWOLD. A Hydrological Prediction System Based on the SVS Land–Surface Scheme: Implementation and Evaluation of the GEM-Hydro platform on the watershed of Lake Ontario. Hydrology and Earth System Sciences (DOI:10.5194/hess-2016-508) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170027.pdf

This work describes the implementation of the distributed GEM-Hydro runoff modeling platform, developed at Environment and Climate Change Canada (ECCC) over the last decade. The latest version of GEM-Hydro combines the SVS (Soil, Vegetation and Snow) land-surface scheme and the WATROUTE routing scheme in order to provide streamflow predictions on a gridded river network. SVS is designed to be two-way coupled to the GEM (Global Environmental Multi-scale) atmospheric model exploited by ECCC for operational weather and environmental forecasting. Although SVS has been shown to accurately track soil moisture during the warm season, it has never been evaluated before for hydrological prediction. This paper presents a first evaluation of its ability to simulate streamflow for all major rivers flowing into Lake Ontario. The skill level of GEM-Hydro is assessed by comparing the quality of simulated flows to that of two established hydrological models, MESH and WATFLOOD, which share the same routing scheme (WATROUTE) but rely on different land–surface schemes. All models are calibrated using the same meteorological forcings, objective function, calibration algorithm, and watershed delineation. Results show that GEM-Hydro performs well and is competitive with MESH and WATFLOOD. A computationally efficient strategy is proposed to calibrate the land-surface model of GEM-Hydro: a simple unit hydrograph is used for routing instead of its standard distributed routing component. The distributed routing part of the model can then be run in a second step to estimate streamflow everywhere inside the domain. Global and local calibration strategies are compared in order to estimate runoff for ungauged portions of the Lake Ontario watershed. Overall, streamflow predictions obtained using a global calibration strategy, in which a single parameter set is identified for the whole watershed of Lake Ontario, show skills comparable to the predictions based on local calibration. Hence, global calibration provides spatially consistent parameter values, robust performance at gauged locations, and reduces the complexity and computational burden of the calibration procedure. This work contributes to the Great Lakes Runoff Inter-comparison Project for Lake Ontario (GRIP-O) which aims at improving Lake Ontario basin runoff simulations by comparing different models using the same input forcings.

Goto, D., J.J. Roberts, S.A. POTHOVEN, S.A. Ludsin, H.A. VANDERPLOEG, S.B. Brandt, and T.O. Höök. Size-mediated control of perch–midge coupling in Lake Erie transient dead zones. Environmental Biology of Fishes (DOI:10.1007/s10641-017-0667-1) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170025.pdf

Transient ecosystem-level disturbances such as oxygen depletion (hypoxia) in aquatic systems modulate species distributions and interactions. In highly eutrophic systems, hypoxic areas (“dead zones”) have expanded around the world, temporarily preventing many demersal predators from accessing their food resources. Here, we investigate how yellow perch (Perca flavescens), an exploited, cool-water mesopredator, interact with their dominant invertebrate prey in benthic habitat–non-biting midge (chironomid) larvae–as bottom-water hypoxia develops in central Lake Erie (United States–Canada) during summer. We apply linear mixed-effects models to individual-level data from basin-wide field surveys on size-based interactions between perch and midge larvae under varying habitat conditions and resource attributes. We test if 1) midge populations (larval body size and density) differ among habitat states (unstratified normoxia, stratified normoxia, and stratified hypoxia); and 2) size-based perch–midge interactions (predator–prey mass ratio or PPMR) differ among habitat states with varying temperature and midge density. Midge populations remained highly abundant after bottom-water oxygen depletion. Despite their high densities, midge larvae also maintained their body size in hypoxic water. In contrast, perch on average consumed relatively smaller (by up to ~64%) midges (higher PPMR) in warmer and hypoxic water, while prey size ingested by perch shrunk less in areas with higher midge density. Our analysis shows that hypoxia-tolerant midges largely allow perch to maintain their consumer–resource relationships in contracted habitats through modified size-mediated interactions in dead zones during summer, revealing plasticity of their trophic coupling in the chronically perturbed ecosystem.

GRONEWOLD, A.D., M.D. Sobsey, and K. McMahan. The compartment bag test (CBT) for enumerating fecal indicator bacteria: Basis for design and interpretation of results. Science of the Total Environment 587-588(1):102-107 (DOI:10.1016/j.scitotenv.2017.02.055) (2017).

For the past several years, the compartment bag test (CBT) has been employed in water quality monitoring and public health protection around the world. To date, however, the statistical basis for the design and recommended procedures for enumerating fecal indicator bacteria (FIB) concentrations from CBT results have not been formally documented. Here, we provide that documentation following protocols for communicating the evolution of similar water quality testing procedures. We begin with an overview of the statistical theory behind the CBT, followed by a description of how that theory was applied to determine an optimal CBT design. We then provide recommendations for interpreting CBT results, including procedures for estimating quantiles of the FIB concentration probability distribution, and the confidence of compliance with recognized water quality guidelines. We synthesize these values in custom user-oriented ‘look-up’ tables similar to those developed for other FIB water quality testing methods. Modified versions of our tables are currently distributed commercially as part of the CBT testing kit.

Kramer, A.M., G. Annis, M.E. Wittmann, W.L. Chadderton, E.S. RUTHERFORD, D.M. Lodge, L.A. Mason, D. BELETSKY, C. Riseng, and J.M. Drake. Suitability of Great Lakes for aquatic invasive species basedon global species distribution models and local aquatic habitat. Ecosphere (DOI:10.1002/ecs2.1883) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170021.pdf

Efficient management and prevention of species invasions requires accurate prediction of where species of concern can arrive and persist. Species distribution models provide one way to identify potentially suitable habitat by developing the relationship between climate variables and species occurrence data. However, these models when applied to freshwater invasions are complicated by two factors. The first is that the range expansions that typically occur as part of the invasion process violate standard species distribution model assumptions of data stationarity. Second, predicting potential range of freshwater aquatic species is complicated by the reliance on terrestrial climate measurements to develop occurrence relationships for species that occur in aquatic environments. To overcome these obstacles, we combined a recently developed algorithm for species distribution modeling—range bagging—with newly available aquatic habitat-specific information from the North American Great Lakes region to predict suitable habitat for three potential invasive species: golden mussel, killer shrimp, and northern snakehead. Range bagging may more accurately predict relative suitability than other methods because it focuses on the limits of the species environmental tolerances rather than central tendency or “typical” cases. Overlaying the species distribution model output with aquatic habitat-specific data then allowed for more specific predictions of areas with high suitability. Our results indicate there is suitable habitat for northern snakehead in the Great Lakes, particularly shallow coastal habitats in the lower four Great Lakes where literature suggests they will favor areas of wetland and submerged aquatic vegetation. These coastal areas also offer the highest suitability for golden mussel, but our models suggest they are marginal habitats. Globally, the Great Lakes provide the closest match to the currently invaded range of killer shrimp, but they appear to pose an intermediate risk to the region. Range bagging provided reliable predictions when assessed either by a standard test set or by tests for spatial transferability, with golden mussel being the most difficult to accurately predict. Our approach illustrates the strength of combining multiple sources of data, while reiterating the need for increased measurement of freshwater habitat at high spatial resolutions to improve the ability to predict potential invasive species.

Lei, R., X. Tian-Kunze, B. Li, P. Heil, J. WANG, J. Zeng, and Z. Tian. Characterization of summer Arctic sea ice morphology in the 135°–175°W sector using multi-scale methods. Cold Regions Science and Technology 133:108-120 (DOI:10.1016/j.coldregions.2016.10.009) (2017).

In summer 2014, sea ice morphological characteristics were investigated in the 135°–175°W sector of the Arctic Ocean using in situ, shipborne, and remote sensing measurements. Sea ice in this sector was deformed and compact compared to previous observations. The average ice area in the region (70°–82.5°N, 135°–175°W) was 7.6 × 105 km2 for 29 July through 6 September 2014, the fourth largest record between 2003 and 2014. This can be attributed to the enhanced multiyear sea ice inflow from north of the Canadian Arctic Archipelago from September 2013 to August 2014. Multiyear ice coverage in the study region on 30 April 2014 was 55%, which was larger than the values in 2005–2013. During the melt season of 2014, the Arctic Dipole had a positive anomaly, associated with enhanced southerly wind. In summer 2014 the marginal ice zone exhibited a distinct ice retreat, whereas the pack ice zone (PIZ) showed strong persistence due to the large coverage of multiyear ice. The northward retreat of the PIZ boundary was < 100 km from late July through early September 2014. In the PIZ of 76–80.5°N, average ice thickness weighted by ice concentration, obtained by shipborne measurements in August 2014 was 0.54 m thicker than that obtained in August 2010 due to enhanced ice deformation and less open waters in 2014. At 81°N, sea ice with modal thickness of 1.48 m reached thermodynamic balance by late August 2014, which was much earlier than that in 2010.

Lekki, J., G. LESHKEVICH, S.A. RUBERG, D. STUART, and A. VANDER WOUDE. et al. Airborne Hyperspectral Sensing of Harmful Algal Blooms in the Great Lakes Region: System Calibration and Validation, From Photons to Algae Information: The Processes In-Between. NASA -Technical Memorandum NASA/TM—2017-219071. NASA, (2017). https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170002298.pdf

LOFGREN, B.M. Comment on Hicham Bahi, et al. Effects of Urbanization and Seasonal Cycle on the Surface Urban Heat Island Patterns in the Coastal Growing Cities: A Case Study of Casablanca, Morocco. Remote Sens. 2016, 8, 829. Remote Sensing 9(1):91 (DOI:10.3390/rs9010091) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170005.pdf

A statement in this recently published paper makes a point that is largely at odds with the main point of the paper that is cited. Stating that higher air temperatures lead to greater evapotranspiration is an oversimplification; the true story is more complex. Although this is by no means central to the conclusions of the paper being commented on, we have demonstrated the danger in taking too literally the idea that air temperature determines potential evapotranspiration.

Lottig, N.R., P.-N. Tan, T. Wagner, K.S. Cheruvelil, P.A. Soranno, E.H. Stanley, C.E. Scott, C.A. STOW, and S. Yuan. Macroscale patterns of synchrony identify complex relationships among spatial and temporal ecosystem. Ecology (2017). (In Press)

Luo, L., J. WANG, T.S. HUNTER, D. Wang, and H.A. VANDERPLOEG. Modeling spring-summer phytoplankton bloom in Lake Michigan with and without riverine nutrient loading. Ocean Dynamics:1-14 (DOI:10.1007/s1023) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170023.pdf

There were two phytoplankton blooms captured by remote sensing in Lake Michigan in 1998, one from March to May, and one during June. In this paper, those phytoplankton blooms were simulated by a coupled physical–biological model, driven by observed meteorological forcing in 1998. The model reasonably reproduced the lake currents. The biological model results, with and without riverine nutrient loading, were compared with the remote sensing data. A 3-month-long donut-like phytoplankton bloom that appeared in southern Lake Michigan was reasonably well simulated only when riverine input was included, indicating the importance of riverine nutrient input for supporting the growth of phytoplankton in Lake Michigan. The model with riverine input also captured a second event-driven phytoplankton bloom during June with weaker magnitude that occurred in mid-south Lake Michigan, which lasted for about 20 days. The major reason for the weaker bloom in June was that vertical mixing in the hydrodynamic model was too weak (leading to a mixed-layer depth of 20 m) to bring the bottom nutrient-rich water up to the epilimnion. High chlorophyll concentration that persisted in Green Bay for almost a year was simulated with less intensity.

MANOME, A.F., L.E. FITZPATRICK, A.D. GRONEWOLD, E.J. ANDERSON, B.M. LOFGREN, C. Spence, J. Chen, C. Shao, D.M. Wright, and C. XIAO. Turbulent Heat Fluxes during an Extreme Lake Effect Snow Event. Journal of Hydrometeorology (DOI:10.1175/JHM-D-17-0062.1) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170031.pdf (IN PRESS)

Proper modeling of the turbulent heat fluxes over lakes is critical for accurate predictions of lake-effect snowfall (LES). However, model evaluation of such a process has not been possible due to the lack of direct flux measurements over lakes. We conducted the first-ever comparison of the turbulent latent and sensible heat fluxes between state-of-the-art numerical models and direct flux measurements over Lake Erie, with a focus on a record LES event in southwest New York in November 2014. The model suite consisted of numerical models that were operationally and experimentally used to provide nowcasts and forecasts of weather and lake conditions. The models captured the rise of the observed turbulent heat fluxes, while the peak values varied significantly. This variation resulted in increased spread of simulated lake temperature and cumulative evaporation as the representation of the model uncertainty. The water budget analysis of atmospheric model results showed that a majority of the moisture during this event came from lake evaporation rather than a larger synoptic system. The unstructured-grid Finite Volume Community Ocean Model (FVCOM) simulations, especially those using the Coupled Ocean-Atmosphere Response Experiment (COARE)-Met Flux algorithm, presented better agreement with the observed fluxes, likely due to the model’s capability in representing the detailed spatial patterns of the turbulent heat fluxes and the COARE algorithm’s more realistic treatment of the surface boundary layer than those in the other models.

Marcus, D.N., A. Pinto, K. Anantharaman, S.A. RUBERG, E.L. Kramer, L. Raskin, and G.L. Dick. Diverse manganese(II)-oxidizing bacteria are prevalent in drinking water systems. Environmental Microbiology Reports 9(2)(DOI:10.1111/1758-2229.12508) (2017).

Manganese (Mn) oxides are highly reactive minerals that influence the speciation, mobility, bioavailability and toxicity of a wide variety of organic and inorganic compounds. Although Mn(II)-oxidizing bacteria are known to catalyze the formation of Mn oxides, little is known about the organisms responsible for Mn oxidation in situ, especially in engineered environments. Mn(II)-oxidizing bacteria are important in drinking water systems, including in biofiltration and water distribution systems. Here, we used cultivation dependent and independent approaches to investigate Mn(II)-oxidizing bacteria in drinking water sources, a treatment plant and associated distribution system. We isolated 29 strains of Mn(II)-oxidizing bacteria and found that highly similar 16S rRNA gene sequences were present in all culture-independent datasets and dominant in the studied drinking water treatment plant. These results highlight a potentially important role for Mn(II)-oxidizing bacteria in drinking water systems, where biogenic Mn oxides may affect water quality in terms of aesthetic appearance, speciation of metals and oxidation of organic and inorganic compounds. Deciphering the ecology of these organisms and the factors that regulate their Mn(II)-oxidizing activity could yield important insights into how microbial communities influence the quality of drinking water.

McArthur, S., K.E. Bailey, T. Murphy, J. Newton, C. Janzen, R. Morrison, S.A. RUBERG, U. Send, and H. Worthington. A National Strategy for a Sustained Network of Coastal Moorings. NOAA IOOS, (2017). https://ioos.noaa.gov/wp-content/uploads/2017/01/NationalStrategyforSustainedNetworkofCoastalMoorings_FINAL.pdf

Meyer, K.A., T.W. DAVIS, S.B. Watson, V.J. Denef, M.A. Berry, and G.J. Dick. Genome sequences of lower Great Lakes Microcystis sp. reveal strain-specific genes that are present and expressed in western Lake Erie blooms. PLoS One (DOI:10.1371/journal.pone.0183859) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170032.pdf

Blooms of the potentially toxic cyanobacterium Microcystis are increasing worldwide. In the Laurentian Great Lakes they pose major socioeconomic, ecological, and human health threats, particularly in western Lake Erie. However, the interpretation of “omics” data is constrained by the highly variable genome of Microcystis and the small number of reference genome sequences from strains isolated from the Great Lakes. To address this, we sequenced two Microcystis isolates from Lake Erie (Microcystis aeruginosa LE3 and M. wesenbergii LE013-01) and one from upstream Lake St. Clair (M. cf aeruginosa LSC13-02), and compared these data to the genomes of seventeen Microcystis spp. from across the globe as well as one metagenome and seven metatranscriptomes from a 2014 Lake Erie Microcystis bloom. For the publically available strains analyzed, the core genome is ~1900 genes, representing ~11% of total genes in the pan-genome and ~45% of each strain’s genome. The flexible genome content was related to Microcystis subclades defined by phylogenetic analysis of both housekeeping genes and total core genes. To our knowledge this is the first evidence that the flexible genome is linked to the core genome of the Microcystis species complex. The majority of strain-specific genes were present and expressed in bloom communities in Lake Erie. Roughly 8% of these genes from the lower Great Lakes are involved in genome plasticity (rapid gain, loss, or rearrangement of genes) and resistance to foreign genetic elements (such as CRISPR-Cas systems). Intriguingly, strain-specific genes from Microcystis cultured from around the world were also present and expressed in the Lake Erie blooms, suggesting that the Microcystis pangenome is truly global. The presence and expression of flexible genes, including strain-specific genes, suggests that strain-level genomic diversity may be important in maintaining Microcystis abundance during bloom events.

Moore, T.S., C.B. Mouw, J.M. Sullivan, M.S. Twardowski, A. BURTNER, A.B. Ciochetto, M.N. McFarland, A.R. Nayak, D. PALADINO, N. Stockley, T.H. JOHENGEN, A.W. Yu, S.A. RUBERG, and A. Weidemann. Bio-optical Properties of Cyanobacteria Blooms in Western Lake Erie. Frontiers in Marine Science (DOI:10.3389/fmars.2017.00300) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170024.pdf

There is a growing use of bio-optical products for quantifying freshwater cyanobacteria blooms, yet their measurements of their inherent optical properties in natural settings are sparse and not well known. Towards improving this knowledge gap in the context of bio-optical algorithms for remote sensing applications, we measured a compliment of inherent optical properties in western Lake Erie during cyanobacteria blooms in the summers of 2013 and 2014. Western Lake Erie is an interesting test bed for optical data collections and bio-optical algorithms, as there are different hydrographic regimes present across a small area that is amenable to remote sensing across a variety of platforms. It is also a region that experiences regular cyanobacteria blooms comprising a variety of toxic and non-toxic species. Sampling included measurements for a suite of environmental and optical parameters, including the volume scattering function, covering a variety of water types inside and outside of cyanobacteria blooms. Large variability of optical properties was observed across the area, with over a two-orders of magnitude range in chlorophyll a concentration. Based on the regional hydrography and the distributions our measurements of biological and optical properties, we partitioned the data into three different sub-regions. The Maumee Bay region, bounded by the southwest corner to Peelee and Kelleys islands 18 towards the east, is shallow and impacted by the Maumee River and contained the highest amount of cyanobacteria dominated by gas-vacuolate Microcystis. This region was characterized by high scattering and absorption coefficients, and a high mean backscatter ratio at 443nm, greater than 0.03. The Detroit River plume region, in the northwest corner, was characterized by low scattering and absorption with particles dominated by inorganic minerals and backscatter ratios closer to 0.023. The third region, east of the islands in the central basin, had moderate absorption and scattering properties and was dominated by Planktothrix, also a gas-vacuolate cyanobacteria with mean backscatter ratios of 0.026. These particle fields in cases were of mixed assemblages of inorganic and organic particles. From a remote sensing perspective, this present a challenge for algorithms because of the optical complexity and diversity of conditions present at the same time over a small region. The measurements focus attention on the optical uniqueness of cyanobacteria blooms, which are extreme compared to non-bloom conditions. These results contribute to establishing baseline values for optical properties specific to freshwater cyanobacteria blooms and applicable to other systems.

Nojavan, F.A., S.S. Qian, and C.A. STOW. Comparative analysis of discretization methods in Bayesian networks. Environmental Modeling & Software 87:64-71 (DOI:10.1016/j.envsoft.2016.10.007) (2017).

A key step in implementing Bayesian networks (BNs) is the discretization of continuous variables. There are several mathematical methods for constructing discrete distributions, the implications of which on the resulting model has not been discussed in literature. Discretization invariably results in loss of information, and both the discretization method and the number of intervals determines the level of such loss. We designed an experiment to evaluate the impact of commonly used discretization methods and number of intervals on the developed BNs. The conditional probability tables, model predictions, and management recommendations were compared and shown to be different among models. However, none of the models did uniformly well in all comparison criteria. As we cannot justify using one discretization method against others, we recommend caution when discretization is used, and a verification process that includes evaluating alternative methods to ensure that the conclusions are not an artifact of the discretization approach.

Nowicki, C.J., D.B. Bunnell, P.M. Armenia, D.M. Warner, H.A. VANDERPLOEG, J.F. CAVALETTO, C.M. Mayer, and J.V. Adams. Biotic and abiotic factors influencing zooplankton vertical distribution in Lake Huron. Journal of Great Lakes Research (DOI:10.1016/j.jglr.2017.08.004) (2017). (IN PRESS)

The vertical distribution of zooplankton can have substantial influence on trophic structure in freshwater systems, particularly by determining spatial overlap for predator/prey dynamics and influencing energy transfer. The zooplankton community in some of the Laurentian Great Lakes has undergone changes in composition and declines in total biomass, especially after 2003. Mechanisms underlying these zooplankton changes remain poorly understood, in part, because few studies have described their vertical distributions during daytime and nighttime conditions or evaluated the extent to which predation, resources, or environmental conditions could explain their distribution patterns. Within multiple 24-h periods during July through October 2012 in Lake Huron, we conducted daytime and nighttime sampling of zooplankton, and measured food (chlorophyll-a), temperature, light (Secchi disk depth), and planktivory (biomass of Bythotrephes longimanus and Mysis diluviana). We used linear mixed models to determine whether the densities for 22 zooplankton taxa varied between day and night in the epi-, meta-, and hypolimnion. For eight taxa, higher epilimnetic densities were observed at night than during the day; general linear models revealed these patterns were best explained by Mysis diluviana (four taxa), Secchi disk depth (three taxa), epilimnetic water temperature (three taxa), chlorophyll (one taxon), and biomass of Bythotrephes longimanus (one taxon). By investigating the potential effects of both biotic and abiotic variables on the vertical distribution of crustacean zooplankton and rotifers, we provide descriptions of the Lake Huron zooplankton community and discuss how future changes in food web dynamics or climate change may alter zooplankton distribution in freshwater environments.

Oliver, S.K., S.M. Collins, P.A. Soranno, T. Wagner, E.H. Stanley, J.R. Jones, C.A. STOW, and N.R. Lottig. Unexpected stasis in a changing world: Lake nutrient and chlorophyll trends since 1990. Global Change Biology (DOI:10.1111/gcb.13810) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170028.pdf (In Press)

The United States (U.S.) has faced major environmental changes in recent decades, including agricultural intensification and urban expansion, as well as changes in atmospheric deposition and climate-all of which may influence eutrophication of freshwaters. However, it is unclear whether or how water quality in lakes across diverse ecological settings has responded to environmental change. We quantified water quality trends in 2913 lakes using nutrient and chlorophyll (Chl) observations from the Lake Multi-Scaled Geospatial and Temporal Database of the Northeast U.S. (LAGOS-NE), a collection of preexisting lake data mostly from state agencies. LAGOS-NE was used to quantify whether lake water quality has changed from 1990 to 2013, and whether lake-specific or regional geophysical factors were related to the observed changes. We modeled change through time using hierarchical linear models for total nitrogen (TN), total phosphorus (TP), stoichiometry (TN:TP), and Chl. Both the slopes (percent change per year) and intercepts (value in 1990) were allowed to vary by lake and region. Across all lakes, TN declined at a rate of 1.1% year-1 , while TP, TN:TP, and Chl did not change. A minority (7%-16%) of individual lakes had changing nutrients, stoichiometry, or Chl. Of those lakes that changed, we found differences in the geospatial variables that were most related to the observed change in the response variables. For example, TN and TN:TP trends were related to region-level drivers associated with atmospheric deposition of N; TP trends were related to both lake and region-level drivers associated with climate and land use; and Chl trends were found in regions with high air temperature at the beginning of the study period. We conclude that despite large environmental change and management efforts over recent decades, water quality of lakes in the Midwest and Northeast U.S. has not overwhelmingly degraded or improved.

POTHOVEN, S.A., and H.A. VANDERPLOEG. Changes in Mysis diluviana abundance and life history patterns following a shift toward oligotrophy in Lake Michigan. Fundamental and Applied Limnology (DOI:10.1127/fal/2017/1039) (2017).

The abundance, biomass, and life history characteristics of Mysis diluviana were evaluated at a 110-m (offshore) and 45-m (nearshore) deep station in southeast Lake Michigan during two time periods, 1995 – 2002 and 2007– 2015. Rapid changes in the lake’s productivity were noted between the two time periods, including declines in chlorophyll, the spring phytoplankton bloom, the size of the deep chlorophyll layer, spring/summer zooplankton biomass, and the benthic amphipod, Diporeia spp., which historically served as a major source of food for fish along with Mysis. Mysis were more abundant during 1995 – 2002 than 2007– 2015, with average declines of 82 % at the nearshore station and 54 % at the offshore station. One factor that may have led to declines in M. diluviana between the two time periods was altered reproductive characteristics due to decreases in food availability. Changes in reproductive characteristics included a shorter period of brood release during the spring and early summer and declines in brood sizes. Other characteristics such as growth rate and generation time did not appear to change between periods, however. Predation from fish appears to be focused on newly emerged juveniles and small adults based on the size of mysids found in stomachs of the predominant planktivorous fish in the lake. Despite declining planktivorous fish abundance during the 2007– 2015 time period, M. diluviana populations have not rebounded as in the past, indicating that there has been a decoupling between predator-prey in the lake following declines in system productivity and the loss of the alternative prey for fish, Diporeia spp.

Props, R., M.L. Schmidt, J. Heyse, H.A. VANDERPLOEG, N. Boon, and V.J. Denef. Flow cytometric monitoring of bacterioplankton phenotypic diversity predicts high population-specific feeding rates by invasive dreissenid mussels. Environmental Microbiology (DOI:10.1111/1462-2920.13953) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170034.pdf (IN PRESS)

Species invasion is an important disturbance to ecosystems worldwide, yet knowledge about the impacts of invasive species on bacterial communities remains sparse. Using a novel approach, we simultaneously detected phenotypic and derived taxonomic change in a natural bacterioplankton community when subjected to feeding pressure by quagga mussels, a widespread aquatic invasive species. We detected a significant decrease in diversity within 1 h of feeding and a total diversity loss of 11.6 ± 4.1% after 3 h. This loss of microbial diversity was caused by the selective removal of high nucleic acid populations (29 ± 5% after 3 h). We were able to track the community diversity at high temporal resolution by calculating phenotypic diversity estimates from flow cytometry (FCM) data of minute amounts of sample. Through parallel FCM and 16S rRNA gene amplicon sequencing analysis of environments spanning a broad diversity range, we showed that the two approaches resulted in highly correlated diversity measures and captured the same seasonal and lake-specific patterns in community composition. Based on our results, we predict that selective feeding by invasive dreissenid mussels directly impacts the microbial component of the carbon cycle, as it may drive bacterioplankton communities toward less diverse and potentially less productive states.

Reavie, E.D., G.V. Sgro, L.R. Estepp, A.J. Bramburger, V.L. Shaw Chraibi, R.W. Pillsbury, M. Cai, C.A. STOW, and A. Dove. Climate warming and changes in Cyclotella sensu lato in the Laurentian Great Lakes. Limnology and Oceanography 62(2):768-783 (DOI:10.1002/lno.10459) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170008.pdf

We present the first evidence of biological change in all of the pelagic Laurentian Great Lakes associated with recent climatic warming. We hypothesized that measured changes in lake temperature, and the resulting physical changes to water columns, were affecting diatom communities in the Great Lakes. A paleolimnological analysis of 10 sediment cores collected from deep locations throughout the Great Lakes basin indicates a recent (30–50 yr) reorganization of the diatom community to one characterized by elevated abundances of several species from the group Cyclotella sensu lato, coinciding with rising atmospheric and water temperatures. These Cyclotella increases are a probable mechanistic result of new physical regimes such as changing stratification depths and longer ice-free periods, and possibly water quality shifts. Efforts to understand the mechanisms of these changes are ongoing, but this compositional reorganization in primary producers could have important implications to Great Lakes food webs.

Reisinger, L.S., A.K. ELGIN, K.M. Towle, D.J. Chan, and D.M. Lodge. The influence of evolution and plasticity on the behavior of an invasive crayfish. Biological Invasions 19(3):815-830 (DOI:10.1007/s10530-016-1346-4) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170009.pdf

Invasion success can be enhanced by evolution and behavioral plasticity, but the importance of these processes for most invasions is not well understood. Previous research suggests there is a genetic basis for differences in growth rate between native and invaded range rusty crayfish (Orconectes rusticus). We hypothesized that invaded range O. rusticus achieve faster growth by allocating more time to foraging and less to defense. We conducted a laboratory experiment to test the effects of range (native or invaded) and plasticity (as induced by exposure to predators) on crayfish behavior. We collected O. rusticus adults and eggs from both ranges, hatched eggs in the lab, and reared juveniles in common conditions either with or without predatory fish. We then quantified adult and juvenile crayfish activity in an experiment with and without predatory fish. In support of our hypothesis, invaded range adults displayed reduced antipredator behavior compared to native range adults. Further, invaded range juveniles were more active than native range juveniles without predators, but all juveniles were inactive with predators. In addition, invaded range juveniles had greater plasticity in behavior than native range juveniles. These results suggest that activity level in the absence of predators has diverged in the invaded range. Because active crayfish consume more prey, this change in behavior may be responsible for rapid growth in the invaded range of O. rusticus, a trait that contributes to the strong ecological impacts of this invasive crayfish.

ROWE, M.D., E.J. ANDERSON, H.A. VANDERPLOEG, S.A. POTHOVEN, A.K. ELGIN, J. WANG, and F. Yousef. Influence of invasive quagga mussels, phosphorus loads, and climate on spatial and temporal patterns of productivity in Lake Michigan: A biophysical modeling study. Limnology and Oceanography (DOI:10.1002/lno.10595) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170018.pdf

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.

Sharrar, A.M., B.E. Flood, J.V. Bailey, D.S. Jones, B.A. Biddanda, S.A. RUBERG, D.N. Marcus, and G.J. Dick. Novel Large Sulfur Bacteria in the Metagenomes of Groundwater-Fed Chemosynthetic Microbial Mats in the Lake Huron Basin. Frontiers in Microbiology (DOI:https://doi.org/10.3389/fmicb.2017.00791) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170029.pdf

Little is known about large sulfur bacteria (LSB) that inhabit sulfidic groundwater seeps in large lakes. To examine how geochemically relevant microbial metabolisms are partitioned among community members, we conducted metagenomic analysis of a chemosynthetic microbial mat in the Isolated Sinkhole, which is in a deep, aphotic environment of Lake Huron. For comparison, we also analyzed a white mat in an artesian fountain that is fed by groundwater similar to Isolated Sinkhole, but that sits in shallow water and is exposed to sunlight. De novo assembly and binning of metagenomic data from these two communities yielded near complete genomes and revealed representatives of two families of LSB. The Isolated Sinkhole community was dominated by novel members of the Beggiatoaceae that are phylogenetically intermediate between known freshwater and marine groups. Several of these Beggiatoaceae had 16S rRNA genes that contained introns previously observed only in marine taxa. The Alpena fountain was dominated by populations closely related to Thiothrix lacustris and an SM1 euryarchaeon known to live symbiotically with Thiothrix spp. The SM1 genomic bin contained evidence of h1-based lithoautotrophy. Genomic bins of both the Thiothrix and Beggiatoaceae contained genes for sulfur oxidation via the rDsr pathway, h1 oxidation via Ni-Fe hydrogenases, and the use of O2 and nitrate as electron acceptors. Mats at both sites also contained Deltaproteobacteria with genes for dissimilatory sulfate reduction (sat, apr, and dsr) and hydrogen oxidation (Ni-Fe hydrogenases). Overall, the microbial mats at the two sites held low-diversity microbial communities, displayed evidence of coupled sulfur cycling, and did not differ largely in their metabolic potentials, despite the environmental differences. These results show that groundwater-fed communities in an artesian fountain and in submerged sinkholes of Lake Huron are a rich source of novel LSB, associated heterotrophic and sulfate-reducing bacteria, and archaea.

Soranno, P.A., (among 23 others), and C.A. STOW. A multi-scaled geospatial and temporal database of lake ecological context and water quality for thousands of U.S. lakes. GigaScience (DOI:10.1093/gigascience/gix101) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170033.pdf (In Press)

Steffen, M.M., T.W. DAVIS, R.M. McKay, G.S. Bullerjahn, L.E. Krausfeldt, J.M.A. Stough, M.L. Neitzey, N.E. Gilbert, G.L. Boyer, T.H. JOHENGEN, D.C. GOSSIAUX, A.M. BURTNER, D. PALLADINO, M.D. ROWE, G.J. Dick, K.A. Meyer, S. Levy, B.E. Boone, R.P. Stumpf, T.T. Wynne, P.V. Zimba, D. Gutierrez, and S.W. Wilhelm. Ecophysiological Examination of the Lake Erie Microcystis Bloom in 2014: Linkages between Biology and the Water Supply Shutdown of Toledo, OH. Environmental Science & Technology (DOI:0.1021/acs.est.7b00856) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170017.pdf

Annual cyanobacterial blooms dominated by Microcystis have occurred in western Lake Erie (U.S./Canada) during summer months since 1995. The production of toxins by bloom-forming cyanobacteria can lead to drinking water crises, such as the one experienced by the city of Toledo in August of 2014, when the city was rendered without drinking water for >2 days. It is important to understand the conditions and environmental cues that were driving this specific bloom to provide a scientific framework for management of future bloom events. To this end, samples were collected and metatranscriptomes generated coincident with the collection of environmental metrics for eight sites located in the western basin of Lake Erie, including a station proximal to the water intake for the city of Toledo. These data were used to generate a basin-wide ecophysiological fingerprint of Lake Erie Microcystis populations in August 2014 for comparison to previous bloom communities. Our observations and analyses indicate that, at the time of sample collection, Microcystis populations were under dual nitrogen (N) and phosphorus (P) stress, as genes involved in scavenging of these nutrients were being actively transcribed. Targeted analysis of urea transport and hydrolysis suggests a potentially important role for exogenous urea as a nitrogen source during the 2014 event. Finally, simulation data suggest a wind event caused microcystin-rich water from Maumee Bay to be transported east along the southern shoreline past the Toledo water intake. Coupled with a significant cyanophage infection, these results reveal that a combination of biological and environmental factors led to the disruption of the Toledo water supply. This scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future.

Stein, S.R., C.R. Roswell, S.A. POTHOVEN, and T.O. Hook. Diets and growth of age-0 walleye in a recently recovered population. Journal of Great Lakes Research 43(2):100-107 (DOI:10.1016/j.jglr.2017.03.019) (2017).

Most fishes undergo ontogenetic diet shifts, progressing from small to larger prey as they grow. The availability of suitable prey throughout early ontogeny can influence growth, survival and ultimately, year-class strength. Simultaneously, due to their numeric abundance and high mass-specific consumption rates, young fish can serve as influential consumers and thereby affect abundance of various prey. The walleye Sander vitreus population in Saginaw Bay, Lake Huron, recently recovered and is now entirely supported by natural reproduction. Recovery coincided with a dramatic decline of alewife Alosa pseudoharengus, a preferred prey of walleye. Thus, we are uncertain what primary prey now support production of young life stages of this recovered walleye population. To this end, we collected young (larval and later-stage young of year) walleye in Saginaw Bay and characterized their growth, diets and cumulative consumption using bioenergetics models. Young walleye progressed from feeding entirely on zooplankton as larvae in April to feeding almost entirely on fish by September. Based on bioenergetics analyses, fish were the most important prey for young walleye cohorts. Shiners Notropis spp., along with invasive rainbow smelt Osmerus mordax and round goby Neogobius melanostomus, were the primary fish prey. In contrast, yellow perch Perca flavescens, an important prey for adult walleye in Saginaw Bay, were largely absent in young walleye diets. Young walleye growth rates were similar to rates observed in other systems, but lower than growth rates previously observed in Saginaw Bay when alewife were abundant and the density of walleye was low.

Sundstrom, S.M., T. Eason, R.J. Nelson, D.G. Angeler, C. Barichievy, A.S. Garmestani, N.A.J. Graham, D. Granholm, L. Gunderson, M. Knutson, K.L. Nash, T. Spanbauer, C.A. STOW, and C.R. Allen. Detecting spatial regimes in ecosystems. Ecology Letters 20(1):19-32 (DOI:10.1111/ele.12709) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170010.pdf

Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological potential (i.e. potential vegetation), and often fail to account for ongoing changes due to stressors such as land use change and climate change and their effects on plant and animal communities. We use Fisher information, an information theory-based method, on both terrestrial and aquatic animal data (U.S. Breeding Bird Survey and marine zooplankton) to identify ecological boundaries, and compare our results to traditional early warning indicators, conventional ecoregion maps and multivariate analyses such as nMDS and cluster analysis. We successfully detected spatial regimes and transitions in both terrestrial and aquatic systems using Fisher information. Furthermore, Fisher information provided explicit spatial information about community change that is absent from other multivariate approaches. Our results suggest that defining spatial regimes based on animal communities may better reflect ecological reality than do traditional ecoregion maps, especially in our current era of rapid and unpredictable ecological change.

VANDERPLOEG, H.A., O. Sarnelle, J.R. LIEBIG, N.R. MOREHEAD, S.D. Robinson, T.H. JOHENGEN, and G.P. Horst. Seston quality drives feeding, stoichiometry and excretion of zebra mussels. Freshwater Biology 62:664-680 (DOI:10.1111/fwb.12892) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170003.pdf


1. Seston availability and quality can affect the condition, nutrient stoichiometry and nutrient excretion of dreissenid mussels and other aquatic consumers. Nutrient excretion by dreissenid mussels may affect phytoplankton community composition by altering nitrogen:phosphorus (N:P) ratios of the water and may be an important accessory factor leading to increased Cladophora and toxic Microcystis blooms in mussel-invaded lakes.

2. We manipulated phosphorus enrichment levels [no (L), moderate (M) and high (H)] and zebra mussel concentrations (1, 2 and 4 g dry mass m−2) to produce a total of nine treatment combinations, each one held in a 31 m3 enclosure in an oligotrophic lake. We measured zebra mussel condition, carbon:nitrogen:phosphorus (C:N:P) tissue stoichiometry, feeding rate and nutrient excretion and egestion as related to varying conditions of chlorophyll a (Chl), particulate phosphorus (PP), particulate organic nitrogen (PON) and seston C:N:P ratios at three time periods: 5–7, 18–20 and 32–34 days subsequent of adding mussels to the enclosures.

3. Consistent with approximate homeostatic control of N and P, there were only modest differences in C:N:P ratios in mussel soft tissue despite greatly different seston C:N:P ratios among enrichment treatments. Mussel condition (mass per unit length) decreased with increased seston N:P, C:P and C:N ratios and percent composition of Cyanobacteria, and increased with percentage composition of cryptophytes and other flagellates.

4. Assimilation rates of Chl and calculated potential assimilation rates of N and P linearly increased (P < 0.05) with increasing seston Chl, PON and PP concentrations.

5. P excretion measured as soluble reactive phosphorus (SRP) significantly decreased in exponential fashion by two orders of magnitude as C:P (R2 = 0.71) and N:P ratios (R2 = 0.66) increased by a factor of 4. P excretion was significantly correlated with seston PP concentration, which varied over a 19-fold range; however, there was much scatter in the relationship (R2 = 0.29). In contrast, NH4-N excretion significantly decreased (R2 = 0.31) with N:P ratio by a factor of 2 over this same N:P range, and was not significantly correlated with PON concentration. Soluble P excretion was significantly correlated with potential P assimilation, whereas NH4 excretion was not significantly correlated with potential N assimilation. The ratio of N:P excreted showed a significant exponential increase with seston N:P ratio.

6. P and N egestion rates were higher than corresponding P and N excretion rates from the same trials; however, the fate of this egested material – whether recycled by resuspension or remaining in the benthos – is not known.

7. Mussel excretion and its impacts are highly context dependent, varying with algal composition, seston stoichiometry, and mussel abundance and feeding rate. The low P excretion but high N excretion observed when mussel feeding stops implies that under poor feeding conditions typical of summer seston, mussels excrete little P but continue excreting N, which would slow production rate of producers such as Cladophora and Microcystis in low-P systems. In contrast, NH4 excretion by mussels may prolong Microcystis blooms as nitrate is used up by the bloom in moderate-P systems.

Wittman, M.T., G. Annis, A.M. Kramer, L.A. Mason, C.M. Riseng, E.S. RUTHERFORD, W.L. Chadderton, D. BELETSKY, J.M. Drake, and D.M. Lodge. Refining species distribution model outputs using landscape-scale habitat data: Forecasting grass carp and Hydrilla establishment in the Great Lakes region. Journal of Great Lakes Research 4(2):298-301 (DOI:10.1016/j.jglr.2016.09.008) (2017).

Forecasts of the locations of species invasions can improve by integrating species-specific climate and habitat variables and the effects of other invaders into predictive models of species distribution. We developed two species distribution models (SDMs) using a new algorithm to predict the global distributions of two nonindigenous species, grass carp (Ctenopharyngodon idella) and Hydrilla (Hydrilla verticillata), with special attention to the North American Great Lakes. We restricted the projected suitable habitat for these species using relevant habitat data layers including accumulated Growing Degree Days (GDD), submersed aquatic vegetation (SAV), wetlands, and photic zone. In addition, we restricted the grass carp niche by the projected Hydrilla niche to explore the potential spatial extent for grass carp given a joint invasion scenario. SDMs showed that climate conditions in the Great Lakes basin were often suitable for both species, with a high overlap between the areas predicted to be climatologically suitable to both species. Restricting Hydrilla regions by GDD and photic zone depth showed that the nearshore zones are primary regions for its establishment. The area of predicted habitat for grass carp increased greatly when including Hydrilla niche as a potential habitat for this species. Integrated risk maps can provide a means for the scientifically informed prioritization of management resources toward particular species and geographic regions.

Xue, P., J.S. Pal, X. Ye, J.D. Lenters, C. Huang, and P.Y. CHU. Improving the Simulation of Large Lakes in Regional Climate Modeling: Two-way Lake-atmosphere Coupling with a 3-D Hydrodynamic Model of the Great Lakes. Journal of Climate 30:1605-1627 (DOI:10.1175/JCLI-D-16-0225.1) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2016/20160052.pdf

Accurate representations of lake-ice-atmosphere interactions in regional climate modeling remain one of the most critical and unresolved issues for understanding large-lake ecosystems and their watersheds. To date, the representation of the Great Lakes two-way interactions in regional climate models is achieved with 1-D lake models applied at the atmospheric model lake grid points distributed spatially across a 2-D domain. While some progress has been made in refining 1-D lake model processes, such models are fundamentally incapable of realistically resolving a number of physical processes in the Great Lakes. In this study we develop a two-way coupled 3-D climate-lake-ice modeling system (named TC-3D-GLARM) aimed at improving the simulation of large lakes in regional climate models and accurately resolving the hydroclimatic interactions. Model results are compared to a wide variety of observational data and demonstrate the unique skill of the coupled 3-D modeling system in reproducing trends and variability in the Great Lakes regional climate, as well as in capturing the physical characteristics of the Great Lakes by fully resolving the lake hydrodynamics. Simulations of the climatology and spatiotemporal variability of lake thermal structure and ice are significantly improved over previous coupled, 1-D simulations. At seasonal and annual time scales, differences in model results are primarily observed for variables that are directly affected by lake surface temperature (e.g., evaporation, precipitation, and sensible heat flux) while no significant differences are found in other atmospheric variables (e.g., solar radiation, cloud cover). Underlying physical mechanisms for the simulation improvements using TC-3D-GLARM are also discussed.


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