October 2017 - Present
Ball, E.E., D.E. Smith, E.J. ANDERSON, and e. al. Water velocity modeling can delineate nearshore and main channel plankton environments in a large river. Hydrobiologia (DOI:10.1007/s10750-018-3556-5) (2018).
Methods to distinguish nearshore and main channel ecosystems within large rivers are essential for observing physical, chemical, and biological features that influence overall river ecosystem function. Water velocity fields based on hydrodynamic modeling of water flow trajectory were used to evaluate water history (i.e., water moving slowly as in a slack water region, or more rapidly, as characteristic of the main channel) prior to passing a given point in the Upper St. Lawrence River. Using this method to differentiate zones in the river, observations of biotic and abiotic variables in nearshore and main channel zones during late spring and summer (June–August) were compared to assess the difference in these water column river ecosystems. Differences in plankton community composition between nearshore and main channel waters along the Upper St. Lawrence River were investigated to test the hypothesis that nearshore and main channel environments in large river systems have different biotic (e.g., phytoplankton, crustacean zooplankton, and rotifer concentrations) and abiotic [e.g., water temperature, specific conductivity, silicate, colored dissolved organic matter (CDOM), and total phosphorus] characteristics. Nearshore water had significantly higher concentrations of CDOM and chlorophyll-a than main channel waters. With distance downstream, crustacean zooplankton and rotifers decreased in abundance in both nearshore and main channel regions. This study describes an effective method for stratified sampling design that differentiates nearshore and main channel ecosystems in the water column of large rivers.
Biddanda, B.A., i. et al., M.E. OGDAHL, Q. LIU, T.H. JOHENGEN, E.J. ANDERSON, and S.A. RUBERG. Chronicles of hypoxia: Time-series buoy observations reveal annually recurring seasonal basin-wide hypoxia in Muskegon Lake – A Great Lakes estuary. Journal of Great Lakes Research (DOI:10.1016/j.jglr.2017.12.008) (2018). (IN PRESS)
We chronicled the seasonally recurring hypolimnetic hypoxia in Muskegon Lake – a Great Lakes estuary over 3 years, and examined its causes and consequences. Muskegon Lake is a mesotrophic drowned river mouth that drains Michigan's 2nd largest watershed into Lake Michigan. A buoy observatory tracked ecosystem changes in the Muskegon Lake Area of Concern (AOC), gathering vital time-series data on the lake's water quality from early summer through late fall from 2011 to 2013 (www.gvsu.edu/buoy). Observatory-based measurements of dissolved oxygen (DO) tracked the gradual development, intensification and breakdown of hypoxia (mild hypoxia <4 mg DO/L, and severe hypoxia <2 mg DO/L) below the ~6 m thermocline in the lake, occurring in synchrony with changes in temperature and phytoplankton biomass in the water column during July–October. Time-series data suggest that proximal causes of the observed seasonal hypolimnetic DO dynamics are stratified summer water-column, reduced wind-driven mixing, longer summer residence time, episodic intrusions of cold DO-rich nearshore Lake Michigan water, nutrient run off from watershed, and phytoplankton blooms. Additional basin-wide water-column profiling (2011–2012) and ship-based seasonal surveys (2003–2013) confirmed that bottom water hypoxia is an annually recurring lake-wide condition. Volumetric hypolimnetic oxygen demand was high (0.07–0.15 mg DO/Liter/day) and comparable to other temperate eutrophic lakes. Over 3 years of intense monitoring, ~9–24% of Muskegon Lake's volume experienced hypoxia for ~29–85 days/year – with the potential for hypolimnetic habitat degradation and sediment phosphorus release leading to further eutrophication. Thus, time-series observatories can provide penetrating insights into the inner workings of ecosystems and their external drivers.
Carrick, H.J., E. Cafferty, A. Ilacqua, S.A. POTHOVEN, and G.L. Fahnenstiel. Seasonal Abundance, Biomass and Morphological Diversity of Picoplankton in Lake Superior: Importance of Water Column Mixing. International Journal of Hydrology 1(6)(DOI:10.15406/ijh.2017.01.00034) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170037.pdf
Picoplankton often regulate the trophic dynamics and key biogeochemical cycles in pelagic environments. That said, comparatively little is known about their seasonal contribution to carbon cycling in Lake Superior, one of the largest lakes world-wide, where attempts to reconcile the carbon and N budgets have not been straightforward. Here, we presented some of few seasonal estimates for both heterotrophic (Hpico) and phototrophic (Ppico) picoplankton abundance, biomass, and morphological diversity in Lake Superior (n=36). Seasonal samples were collected at two offshore stations in the central basin of Lake Superior on six cruises conducted at monthly intervals (MayOctober 2013). Fractionated chlorophyll analysis revealed that algae in the 2-20 µm size category (nanoplankton) constituted > 50% of the assemblage while the Ppico size fraction constituted ~25% (total chlorophyll < 1 µg • L-1). The Hpico assemblage was dominated by simply cocci-forms (i.e., eubacteria). Hpico abundance ranged from 140 to 871 x 103 cells • mL-1, and on average, supported ~8-fold greater numbers compared with the abundance of Ppico (19 to 146 x 103 cells • mL-1). Ppico was dominated by phycoerythrin-rich, single-celled taxa, whose abundance was relatively constant from May-September. The concentration of chlorophyll, Hpico (bacteria), and pico- eukaryotes increased with mixing depth; however, chlorophyll and Ppico numbers exhibited a 2-fold increase in October when bacterial numbers were at their lowest level. Despite these differences in seasonal dynamics, overall carbon estimates for both Hpico and Ppico were comparable, and collectively constituted a substantial faction of plankton carbon in the lake (mean 11.27 and 11.00 µgC • L-1, respectively), indicating their importance in reconciling the carbon budget for Lake Superior.
Filstrup, C.T., T. Wagner, S.K. Oliver, C.A. STOW, K.E. Webster, E.H. Stanley, and J.A. Downing. Evidence for regional nitrogen stress on chlorophyll a in lakes across large landscape and climate gradients. Limnology and Oceanography 63(S1):S324-S339 (DOI:doi.org/10.1002/lno.10742) (2018). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170036.pdf
Nitrogen (N) and phosphorus (P) commonly stimulate phytoplankton production in lakes, but recent observations from lakes from an agricultural region suggest that nitrate may have a subsidy-stress effect on chlorophyll a (Chl a). It is unclear, however, how generalizable this effect might be. Here, we analyzed a large water quality dataset of 2385 lakes spanning 60 regions across 17 states in the Northeastern and Midwestern U.S. to determine if N subsidy-stress effects on phytoplankton are common and to identify regional landscape characteristics promoting N stress effects in lakes. We used a Bayesian hierarchical modeling framework to test our hypothesis that Chl a–total N (TN) threshold relationships would be common across the central agricultural region of the U.S. (“the Corn Belt”), where lake N and P concentrations are high. Data aggregated across all regions indicated that high TN concentrations had a negative effect on Chl a in lakes with concurrent high total P. This large-scale pattern was driven by relationships within only a subset of regions, however. Eight regions were identified as having Chl a–TN threshold relationships, but only two of these regions located within the Corn Belt clearly demonstrated this subsidy-stress relationship. N stress effects were not consistent across other intense agricultural regions, as we hypothesized. These findings suggest that interactions among regional land use and land cover, climate, and hydrogeology may be important in determining the synergistic conditions leading to N subsidy-stress effects on lake phytoplankton
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.
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 drivers. Ecosphere 8(12)(2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170035.pdf
Ecology has a rich history of studying ecosystem dynamics across time and space that has been motivated by both practical management needs and the need to develop basic ideas about pattern and process in nature. In situations in which both spatial and temporal observations are available, similarities in temporal behavior among sites (i.e., synchrony) provide a means of understanding underlying processes that create patterns over space and time. We used pattern analysis algorithms and data spanning 22–25 yr from 601 lakes to ask three questions: What are the temporal patterns of lake water clarity at sub-continental scales? What are the spatial patterns (i.e., geography) of synchrony for lake water clarity? And, what are the drivers of spatial and temporal patterns in lake water clarity? We found that the synchrony of water clarity among lakes is not spatially structured at sub-continental scales. Our results also provide strong evidence that the drivers related to spatial patterns in water clarity are not related to the temporal patterns of water clarity. This analysis of long-term patterns of water clarity and possible drivers contributes to understanding of broad-scale spatial patterns in the geography of synchrony and complex relationships between spatial and temporal patterns across ecosystems.
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
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.
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.
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 23(12):5455-5467 (DOI:10.1111/gcb.13810) (2017). https://www.glerl.noaa.gov/pubs/fulltext/2017/20170028.pdf
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., C.P. Madenjian, and T.O. Hook. Feeding ecology of the walleye (Percidae, Sander vitreus), a resurgent piscivore in Lake Huron (Laurentian Great Lakes) after shifts in the prey community. Ecology of Freshwater Fish (DOI:10.1111/eff.12315) (2016). https://www.glerl.noaa.gov/pubs/fulltext/2016/20160045.pdf
Recovering populations of piscivores can challenge understanding of ecosystem function due to impacts on prey and to potentially altered food webs supporting their production. Stocks of walleye (Percidae, Sander vitreus), an apex predator in the Laurentian Great Lakes, crashed in the mid-1900s. Management efforts led to recovery by 2009, but recovery coincided with environmental and fish community changes that also had implications for the feeding ecology of walleye. To evaluate potential changes in feeding ecology for this apex predator, we assessed diets in the main basin of Lake Huron and in Saginaw Bay, a large embayment of Lake Huron, during 2009–2011. Walleye switched their diets differently in the main basin and Saginaw Bay, with non-native round goby (Gobiidae, Neogobius melanostomus) and rainbow smelt (Osmeridae, Osmerus mordax) more prevalent in diets in the main basin, and invertebrates, yellow perch (Percidae, Perca flavescens) and gizzard shad (Clupeidae, Dorosoma cepedianum) more prevalent in diets in the bay. Feeding strategy plots indicated that there was a high degree of individual specialisation by walleye in the bay and the main basin. Bioenergetic simulations indicated that walleye in Saginaw Bay need to consume 10%–18% more food than a walleye that spends part or all of the year in the main basin, respectively, in order to achieve the same growth rate. The differences in diets between the bay and main basin highlight the flexibility of this apex predator in the face of environmental changes, but changes in diet can alter energy pathways supporting piscivore production.
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.
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 62(6):2626-2649 (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.
SMITH, J.P., R. MILLER, R.W. MUZZI, S.A. CONSTANT, K.S. BEADLE, D. PALLADINO, T.H. JOHENGEN, and S.A. RUBERG. An Implementation of a Database Management System for Real-Time Large-Lake Observations. Marine Technology Society Journal 51(6):5-9 (DOI:10.4031/MTSJ.51.6.2) (2017).
Real-time environmental observations have typically been stored in relatively inaccessible flat text files. In this publication, we present an instance of a PostgreSQL database management system to ingest real-time observations from four buoys in North America's western Lake Erie. Data are transmitted via a cellular data modem, initially archived as text data, and then ingested into the database for further analysis and retrieval. The database utilizes two tables with parallel structure to archive data in a consistent manner. We assign unique keys to instrumentation configurations as they change within and between monitoring seasons. Daily sets of data are linked to their configurations by key and thus are documented, allowing for efficient browsing of user desired data. In addition, we quality check data and archive the findings in a corresponding matrix. With assistance from server-side processing, we produce a web interface for the database. We hope the design of this database allows for relatively simple deployment in domains other than western Lake Erie.
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)
STOW, C.A., K.E. Webster, T. Wagner, N.R. Lottig, P.A. Soranno, and Y.K. Cha. Small values in big data: The continuing need for appropriate metadata. Ecological Informatics 45:26-30 (DOI:10.1016/j.ecoinf.2018.03.002) (2018).
Compiling data from disparate sources to address pressing ecological issues is increasingly common. Many ecological datasets contain left-censored data – observations below an analytical detection limit. Studies from single and typically small datasets show that common approaches for handling censored data — e.g., deletion or substituting fixed values — result in systematic biases. However, no studies have explored the degree to which the documentation and presence of censored data influence outcomes from large, multi-sourced datasets. We describe left-censored data in a lake water quality database assembled from 74 sources and illustrate the challenges of dealing with small values in big data, including detection limits that are absent, range widely, and show trends over time. We show that substitutions of censored data can also bias analyses using ‘big data’ datasets, that censored data can be effectively handled with modern quantitative approaches, but that such approaches rely on accurate metadata that describe treatment of censored data from each source.
WANG, J., J. Kessler, F. Hang, H. HU, A.H. CLITES, and P. CHU. Analysis of Great Lakes Ice Cover Climatology: Winters 2012-2017. NOAA Technical Memorandum GLERL-171. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 25 pp. (2017). https://www.glerl.noaa.gov/pubs/tech_reports/glerl-171/tm-171.pdf
This report analyzes the 2012-2017 ice cycles in the Great Lakes region through dates of first (last) ice, ice duration, ice cover distribution, ice cover anomalies, and ice cover seasonal progression. Line plots and ice charts aid the discussion of seasonal and spatial patterns of ice cover over the Great Lakes during each winter season. The data, which is in the form of digitized ice charts, was produced by the National Ice Center and are available to download from their website as ASCII files, http://www.natice.noaa.gov/products/great_lakes.html.
WANG, J., J. Kessler, F. Hang, H. HU, A.H. CLITES, and P. CHU. Great Lakes Ice Climatology Update of Winters 2012-2017: Seasonal Cycle, Interannual Variability, Decadal Variability, and Trend for the period 1973-2017. NOAA Technical Memorandum GLERL-170. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (2017). https://www.glerl.noaa.gov/pubs/tech_reports/glerl-170/tm-170.pdf
The 6-winter (2012-2017) digital ice cover data set includes 996 ice charts of total ice concentration, which were added to GLERL’s ice dataset. This report updates GLERL’s 45-winter ice climatology dataset, 1973-2017. The temporal distribution of the ice charts is also summarized. The original ice charts were produced by the U.S. National Ice Center (NIC) and downloaded from their website as ASCII files, http://www.natice.noaa.gov/products/great_lakes.html. The data format, quality control, processing using ArcGIS, and availability are the same as sections 2-6 of Wang et al. (2012a)
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