5/19/2015  |   10:30 - 10:45   |  103AB

FACTORS REGULATING INTERANNUAL VARIABILITY OF CLADOPHORA ABUNDANCE IN LAKE MICHIGAN Excess Cladophora growth is a significant management problem on several of the Laurentian Great Lakes. As such, there is a need to understand the mechanisms that regulate it growth. A time series of Cladophora biomass at a nearshore site in Lake Michigan reveals significant interannual variability, with mid-summer peak biomass ranging from 45 to 268 grams dry weight per square meter. We used this data set, along with other meteorological and in-lake variables, to explore the factors regulating Cladophora biomass. Application of a Cladophora growth model suggests that the proximal regulators of Cladophora production are dissolved P concentration and light, with the relative importance of each of these varying among years. An empirical multiple regression model was developed that predicts summer peak biomass based on surface irradiance and surface temperature in May. Potential mechanisms responsible for this relationship are discussed.

Harvey Bootsma (Primary Presenter/Author), University of Wisconsin-Milwaukee, hbootsma@uwm.edu;


Zac Driscoll (Co-Presenter/Co-Author), UW-Milwaukee School of Freshwater Sciences, zgd@uwm.edu;


Benjamin Turschak (Co-Presenter/Co-Author), University of Wisconsin-Milwaukee, turschak@uwm.edu;


Erin Wilcox (Co-Presenter/Co-Author), Green Bay Metropolitan Sewerage District, erinm.wilcox@gmail.com;

5/19/2015  |   10:45 - 11:00   |  103AB

A LOCAL-TO-GLOBAL-CHARACTERIZATION OF CYANOTOXINS IN FRESHWATER LAKES Mixtures of cyanobacterial secondary metabolites found in freshwater are important toxicologically for potential human exposures during recreational activities and in drinking water. Our laboratory received over 500 samples for cyanotoxin analysis from lakes in North America, Iceland, Europe and South America. Thirteen cyanopeptides were detected using HPLC-MS/MS. The resulting data characterizes cyanotoxin profiles of 36 lake sites between 2008 and 2013. The goal of these analyses was to compare and contrast the types and concentrations of toxic or bioactive cyanopeptides present in lakes from around the world, with identical laboratory methods. All toxins measured were detected in at least one sample. Anabaenopeptin B, anabaenopeptin F, microcystin-LR, and cyanopeptolin 1041 were most frequently detected with occurrences of 52.53, 29.63, 29.63, and 25.25%, respectively. Cyanopeptolin 1020 was least frequently detected in 4.38% of samples. The highest toxin concentration detected was MC-LR at 974 ?g/L. This study illustrates that cyanotoxin profiles differ despite similarities in lake geography or trophic status. Future work will examine cyanotoxin profiles of these lakes in relation to global land-use patterns and lake characteristics.

Chelsea A. Weirich (Primary Presenter/Author), Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, cweirich@uwm.edu;


Todd Miller (Co-Presenter/Co-Author), University of Wisconsin-Milwaukee, millertr@uwm.edu;

5/19/2015  |   11:00 - 11:15   |  103AB

CHANGES IN N2-FIXING ALGAL SPECIES ASSEMBLAGES ACROSS A STREAM TEMPERATURE GRADIENT: IMPLICATIONS OF WARMING FOR SPECIES COMPOSITION AND ECOSYSTEM FUNCTION In nitrogen-poor streams in Iceland algal abundance and biomass are dominated by N₂-fixing algae (cyanobacteria and diatoms in the Rhopalodiaceae which contain endosymbiotic cyanobacteria) that generally increase concomitantly with N₂-fixation rates and stream temperature. Factors that drive distribution patterns of specific species which exhibit both broad and narrow temperature tolerances are not well understood. To determine how temperature influences N₂-fixing algal species, we compared algal abundance and species assemblage structure across a gradient of geothermally-heated streams (7-28°C) to those from a streamside-channel experiment sourced by a cold stream and heated (indirectly via heat exchangers placed in geothermal pools) across a similar range of temperatures. Species distributions varied with temperature for both the landscape and artificial channels with several taxa showing similar temperature preferences and tolerance ranges. Warmer temperatures supported Cylindrospermum and Anabaena-like taxa while Nostoc dominated across all temperatures but showed species level variation. Rhopalodiaceae responded to shifts in architecture associated with other algal taxa. When combined with species-specific data on N₂-fixation rates, knowledge of species-specific ecology will strengthen predictive models developed for understanding stream function in a warming world.

Paula Furey (Primary Presenter/Author), St. Catherine University, pcfurey@stkate.edu;


Jill Welter (Co-Presenter/Co-Author), St. Catherine University, jill.welter@gmail.com;


Delorianne Sander (Co-Presenter/Co-Author), St.Catherine University, drsander12@gmail.com;


Ashley Mickens (Co-Presenter/Co-Author), Miami University, mickenam@miamioh.edu ;


Wyatt Cross (Co-Presenter/Co-Author), Montana State University, wyatt.cross@montana.edu ;

5/19/2015  |   11:15 - 11:30   |  103AB

ESTIMATING SALMON ENRICHMENT AND DISTURBANCE ON PERIPHYTON OVER THE COURSE OF A RUN USING COUPLED DIN, PERIPHYTON N, AND CHLOROPHYLL A Salmon spawners can influence periphyton biomass via nutrient subsidies and physical disturbance to benthos. The net effect of salmon, however, depends on the context, mainly defined by discharge, light regime, and preexisting nutrient availability. Here we present a model for the coupled dynamics of dissolved inorganic nitrogen (DIN), chlorophyll a (chla), and periphyton N content (Nb) in which salmon density influences inorganic DIN concentration positively and chla negatively. We used measurements of PAR, temperature, discharge, chla, DIN and NP (collected daily to weekly) from a stream in southeast Alaska to estimate model parameters. Our formulation and analysis enables us to estimate parameters governing both salmon enrichment and disturbance effects on DIN, chla, and Nb. We performed Monte Carlo simulations of DIN, chla, and NP dynamics in the absence of salmon to quantify the significance of the net salmon effect during the run. Our dynamic model allow us to quantify the effects of salmon over the course of a run, identifying periods when salmon enrichment or disturbance dominate.

Ford Ballantyne (Primary Presenter/Author), University of Georgia, fb4@uga.edu;


Janine Rüegg (Co-Presenter/Co-Author), University of Lausanne, janine.ruegg@unil.ch;


Chao Song (Co-Presenter/Co-Author), Taizhou University, songchaonk@163.com ;


Dominic Chaloner (Co-Presenter/Co-Author), University of Notre Dame, dchaloner@nd.edu;


Gary Lamberti (Co-Presenter/Co-Author), University of Notre Dame, lamberti.1@nd.edu;

5/19/2015  |   11:30 - 11:45   |  103AB

SPECIES RICHNESS OF DIATOMS AND SOFT-BODIED ALGAE IN STREAMS WITHIN A LAND-USE MOSAIC IN SOUTHERN NY STATE We characterized benthic algal biodiversity in sixty 1st-5th order streams in a mosaic of forest, rural, agricultural, and urban landscapes. Marked differences in diatom richness (urban minima 17-27; forested, rural streams maxima 70-120) and soft-bodied algae corresponded with significant differences in conductance, pH, nutrients, DOC, Ca, and Na among landuse categories. Achnanthidium minutissimum, A. rivulare, Enycyonema minutum, Coccoconeis placentula, Planothidium frequentissimum /lanceolata, and Remeria sinuata persisted year-round in >60% of all sites, while summer-dominant taxa (Gomphonmena parvulum, Navicula minima, Cymbella minuta) were uncommon in spring. Frequencies of common softbodied taxa (Audouinella hermanni, Phormidium autumnale, Chamaesiphon minutus, Stigeoclonium tenue, Homeothrix varians, Ph. retzii, Ulothrix zonata, Cladophora glomerata) exhibited differences among land-use and season. Macroalgal taxa richness ranged from 2 to 13 per site (mean 6.5), with greater richness in autumn-winter vs. spring-summer. Elevated conductance, N and P correlated strongly with landuse and species richness differences. Several cyanobacteria (Capsosira brebissonii, Coleodesmium wrangelii, Cyanodermatium fluminense) and green algae (Gongrosira fluminensis, G. debaryana), infrequently reported in North America, were common in upland NY streams, suggesting they are taxa overlooked in past surveys.

John Wehr (Primary Presenter/Author), Louis Calder Center - Fordham University, wehr@fordham.edu;
Professor of Biology at the Louis Calder Center, the biological field station of Fordham University. Directs freshwater ecology research lab. Supervised graduate, undergraduate and high school students in independent research. - Mentored 11 Masters and 7 PhD theses Editor, Freshwater Algae of North America (Academic Press) Specialties: - Phytoplankton and benthic algal identification - Phycology - Biostatistics - Stream ecology - Water chemistry

Kam Truhn (Co-Presenter/Co-Author), Louis Calder Center - Fordham University, truhn@fordham.edu;


Alissa Perrone (Co-Presenter/Co-Author), Louis Calder Center - Fordham University, aperrone@fordham.edu ;

5/19/2015  |   11:45 - 12:00   |  103AB

TEMPORAL DYNAMICS OF TOXIC CYANOBACTERIAL PEPTIDES IN A EUTROPHIC LAKE Large accumulations of cyanobacteria threaten the health and sustainability of freshwater ecosystems due to their harmful effects on aquatic biota. Here we provide time series concentrations of cyanobacterial toxins (including four microcystins) and secondary bioactive metabolites (CTSMs) at sub- daily scales in Lake Winnebago, a hypereutrophic environment in Wisconsin that serves as a drinking water resource to four major cities. Thirteen CTSMs were targeted in this study, detected from lyophilized water samples using liquid chromatography -electrospray ionization tandem mass spectrometry. Of the CTSMs targeted, all but two were detected in the lake on at least one date with max combined levels of 30.49 ng/ml. Temporal variability showed that CTSM levels varied by orders of magnitude over the course of hours. We observed that the maximum toxin concentration was most abundant prior to the onset of the bloom event, concomitant with diel cycling of the algal community. As such, toxin concentration was not correlative with either chlorophyll or phycocyanin, but rather with diel cycling. This is the first study to provide an analysis of CTSMs in lakes at sub- daily scales.

Sarah Bartlett (Primary Presenter/Author), University of Wisconsin-Milwaukee, bartle34@uwm.edu;


Chelsea Weirich (Co-Presenter/Co-Author), University of Wisconsin-Milwaukee, caweirich@uwm.edu;


Todd Miller (Co-Presenter/Co-Author), University of Wisconsin-Milwaukee, millertr@uwm.edu;