PSA Presidential Plenary Symposium: Algae and the Great Lakes

PSA Presidential Plenary Symposium: Algae and the Great Lakes

July 26, 2016

8:30-12:00

John Carroll University (University Heights, OH), Dolan Hall

 

 

HYPOXIA IN LAKE ERIE IS MOSTLY DRIVEN BY DIATOMS

Reavie, E.D., Natural Resources Research Institute, University of Minnesota Duluth, Duluth, MN

Cai, M., Natural Resources Research Institute, University of Minnesota Duluth, Duluth, MN

Twiss, M. R., Department of Biology, Clarkson University, Potsdam, NY

Carrick, H. J., Dept. of Biology & Institute for Great Lakes Research, Central Michigan University,

Mount Pleasant, MI

Davis, T. W., National Oceanic and Atmospheric Administration, Great Lakes Environmental

Research Laboratory, Ann Arbor, MI

Johengen, T. H., Cooperative Institute for Limnology & Ecosystem Research, Ann Arbor, MI.

Gossiaux, D., National Oceanic and Atmospheric Administration, Great Lakes Environmental

Research Laboratory, Ann Arbor, MI

Smith, D. E., Dept. of Biostatistics and Informatics, Colorado School of Public Health, Aurora, CO

Palladino, D., Cooperative Institute for Limnology & Ecosystem Research, Ann Arbor, MI

Burtner, A., Cooperative Institute for Limnology & Ecosystem Research, Ann Arbor, MI

Sgro, G. V., Department of Biology, John Carroll University, OH

 

Re-eutrophication and harmful algal blooms in Lake Erie have resulted in a renewed call for remedial measures such as reductions of phosphorus loads. Nutrient reductions can have a remedial effect on hypolimnetic anoxia by reducing algal biomass. However, winter-spring blooms of diatoms have not been fully recognized as a source of algal biomass supporting summer hypoxia. We compared spring and summer phytoplankton abundance in central and western Lake Erie based on monitoring data to show that spring phytoplankton biovolume was 1.5- to 6-fold greater than summer biovolume and that most spring biovolume was composed of filamentous diatoms, primarily Aulacoseira islandica, that is likely supported by an increasing silica load from Lake Huron. The rise of silica export was attributed to the dreissenid mussel invasion and establishment that reduced diatom abundance in Lake Huron and thereby increased silica availability in the receiving water body of Lake Erie. Winter-spring diatoms, not summer cyanophytes, are likely contributing the majority of the carbon load to the hypolimnion of the central basin of Lake Erie, so remedial measures aimed at reducing hypoxia in Lake Erie must consider these early-year blooms as important contemporary features of the lake that deliver algal biomass to the profundal zone.

 

NEARSHORE VS. OFFSHORE CYANOBACTERIAL BLOOMS IN LAKE ERIE

Bullerjahn, G. S., Biological Sciences, Bowling Green State University, Bowling Green, OH

McKay, R. M., Biological Sciences, Bowling Green State University, Bowling Green, OH

Rozmarynowycz, M., Biological Sciences, Bowling Green State University, Bowling Green, OH

Davenport, E., Biological Sciences, Bowling Green State University, Bowling Green, OH

Tuttle, T., Biological Sciences, Bowling Green State University, Bowling Green, OH

Watson, S.B., Environment and Climate Change Canada, Canadian Centre for Inland Waters,

Burlington, Ontario, Canada

Davis, T., NOAA-GLERL, Ann Arbor, MI

 

Whereas much attention has been devoted to studying the Microcystis harmful algal bloom (HAB) events in western Lake Erie, tributary sites are often affected by persistent blooms of Planktothrix, a filamentous microcystin-producing cyanobacterium.  Our lab is examining the factors allow these organisms to occupy different ecological niches.  Regarding Planktothrix, HABs are typically of longer duration (May-October), routinely yielding microcystin levels in excess of 20 ppb.   In agreement with prior studies on the Planktothrix bloom in Grand Lake St. Marys (OH), Sandusky Bay midsummer dissolved inorganic N concentrations often fall below detection, and bottle assays indicate that enhancement of bloom conditions is dependent on N additions, rather than P.  Losses of N in Sandusky Bay are attributed in part to high rates of denitrification in the sediments.  We hypothesize that N availability is a major driver of Planktothrix dominance in the Bay, distinct from open water Microcystis HABs in which P is traditionally viewed as the key factor for biomass production.  Indeed, work in other labs has shown that Microcystis is an effective scavenger for P.  The success of Planktothrix in an N-limited system is notable given that this genus is not an N fixer, but metagenomic analyses reveal a diverse heterotrophic bacterial community of N fixers contributing new N into the system.  Analysis of Sandusky Bay qPCR, metagenomes and 16S iTags also reveals that the bloom is largely populated with nontoxic Planktothrix genotypes, and that Planktothrix presence and abundance is correlated with N speciation.  With respect to offshore Microcystis blooms, we are examining diel metatranscriptomes from the 2014 HAB that temporarily shut down the Toledo water supply. Currently, we are analyzing gene expression patterns for functions associated with photosynthetic electron transfer, P scavenging and microcystin synthesis.

 

LONG-TERM REMOTE SENSING ON LAKE ERIE USING LANDSAT

Ho, J. C., Dept. of Civil & Environmental Engineering, Stanford University, and Dept. of Global

Ecology, Carnegie Institution for Science, CA

Michalak, A. M., Dept. of Global Ecology, Carnegie Institution for Science, CA

Stumpf, R. P., National Centers for Coastal Ocean Science, National Oceanic and Atmospheric

Administration, MI

Bridgeman, T. B., Dept. of Environmental Sciences/Lake Erie Center, University of Toledo, OH

 

Information on historical phytoplankton blooms can yield insight that can be used to tackle present-day challenges in inland waters. Thus far, however, attempts to use historical information to understand long-term changes relevant for present-day management have been stymied by a limited historical record in many freshwater systems. For Lake Erie, we augment the existing record based on MERIS imagery that begins in 2002 by generating new information on the spatial extent and timing of blooms from Landsat 5 imagery for 1984-2001. Despite limitations stemming from Landsat’s long revisit period and regular cloudiness obscuring scenes, we demonstrate that Landsat is able to generate robust long-term data on Lake Erie and that remotely-sensed historical data add relevant context for addressing current blooms. This new historical record documenting the presence, magnitude, and timing of past blooms expands existing scientific capability to understand the dynamics of bloom occurrence and growth by adding nearly two decades of information to what is known about blooms in Lake Erie.

 

LAKE ERIE’S RE-EUTROPHICATION: DEGRADATION, ADAPTATION, AND RESTORATION

Kane, D. D., Natural Science, Applied Science, and Mathematics Division, Defiance College,

Defiance, OH.

Chaffin, J. D., F.T. Stone Laboratory, Ohio State University, Put-In-Bay, OH

Conroy, J. D., Inland Fisheries Research Unit, Ohio Department of Natural Resources, Division of

Wildlife, Hebron, OH

Culver, D. A., Limnology Laboratory, Department of Evolution, Ecology, and Organismal Biology,

The Ohio State University, Columbus, OH

 

Total phytoplankton and cyanobacterial biomasses in Lake Erie’s western and central basins have been increasing since the mid 1990’s, following several decades of declines directly tied to phosphorus abatement.  These increases, coupled with hypoxia at a variety of spatial and temporal scales, provide evidence that Lake Erie is currently undergoing re-eutrophication.  Both short-term and long-term management actions are necessary to minimize degradation of this resource.  Herein, we distinguish between short-term adaptation by the lake’s users and long-term restoration of the lake.  Short-term adaptation includes monitoring bloom formation and location, toxicity, and if blooms are impacting end users via contaminated water, closed beaches, or other Beneficial Use Impairments (BUIs).  Specifically, we provide data related to the efficacy of monitoring buoys as early-warning systems for drinking water treatment plants.  Short-term adaptations by Lake Erie’s users are necessary and relatively inexpensive compared to what must be done to decrease Cyanobacterial Harmful Algal Blooms (CHABs) and lessen the extent/duration of hypoxia to restore Lake Erie to a more desirable state.  Further, long-term restoration actions must be considered within the context of conditions predicted by climate change scenarios, not current conditions.