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GLERL ECOHAB
Collaborators
Juli Dyble, George Leshkevich, Mike McCormick, Henry Vanderploeg
Great Lakes Environmental Research Laboratory (Glerl home)
Bopi Biddunda, Rick Rediske Grand Valley State University
(GVSU web site)
Dave Millie University of Southern Florida (USF web site)
Pat Tester NOAA National Ocean Service (NOS web site)
Don Scavia University of Michigan Sea Grant (Michigan Sea Grant web site)
Executive Summary
In the Great Lakes a resurgence of harmful algal blooms has been noted in the last decade. These events were surprising given the success of eutrophication controls enacted during the 1970s and 1980s. These new HABs appeared to be related to the filtering activities of recently established non-indigenous mussels, genus Dreissena. The most common HAB in the Great Lakes is the cyanobacteria, Microcystis, which produces the hepatotoxin, microcystin. During the past year, we initiated a monitoring and event response program to Microcystis blooms in several areas of the Great Lakes (Saginaw Bay, western Lake Erie, Muskegon Lake, and Bear Lake). Results from this monitoring were posted on a web site at GLERL, and made available to the public ( http://www.glerl.noaa.gov/res/Centers/HABS/habs.html). This web site was the first HAB event response site in the Great Lakes, and should serve as a model for the development of public response activities. This year we plan to continue development of this monitoring and event program
Project Rationale
Bloom-forming, toxic cyanobacteria occur worldwide in nutrient-enriched freshwaters. Such blooms can have disastrous short- and long- term consequences for water quality and resource utilization. Consequently, cyanobacteria have been the focus of considerable research and information exists concerning the factors allowing a species to exploit environmental conditions and initiate blooms. In particular, cyanobacterial toxins are noted causative agents for human and animal illness/mortality as well as a litany of environmental-, legal-, and recreational-related problems.
Microcystis aeruginosa is the dominant bloom-forming, toxic cyanobacterium occurring in the Great Lakes. Microcystis has (again) become a dominant component of the summer phytoplankton in both Saginaw Bay and western Lake Erie after being a relatively minor component during the late 1980s and early 1990s. Moreover, preliminary studies have verified the presence of the cyanotoxin, microcystin, in both systems. As such, the recent blooms of Microcystis have caused considerable concern due to dependence on these waters as a resource and the health risks attributable to microcystins. In particular, microcystin concentrations for Saginaw Bay (2.4 g/L, Vanderploeg et al. 2001) have exceeded the recommended limit of 1 µg/L of microcystin for drinking water (World Health Organization 1998). However, limited information concerning rates of and factors controlling microcystin production exists for the Great Lakes. In the past two years, we have regularly found concentrations of microcystin > 1ug/l in Saginaw Bay and western Lake Erie during the summer when surface scums of Microcystis were absent. Additionally, we have documented concentrations of microcystin in two coastal lakes on the eastern shore of Lake Michigan exceeding 200 ug/l when blooms of Microcystis were present.
2006 Plans
The plan of work consists of coordinating remote sensing imagery with field sampling in order to document the extent and significance of harmful algal blooms in the Great Lakes. The GLERL Coastwatch and NOS satellite teams will provide MODIS and SEAWIFTS imagery to two summer interns, who will be responsible for field sampling. If satellite imagery indicates the presence of a cyanobacteria bloom, the interns will initiate sampling to characterize the bloom, and if a Microcystis bloom, determine the microcystin concentrations. One summer intern wil be responsible for coordinating, monitoring and analysis for Saginaw Bay and western Lake Erie, while the other intern will be responsible for working on a series of lakes in West Michigan (Bear Lake, Muskegon Lake, Spring Lake, etc.) where large blooms and high concentrations of microcystin have been noted. Additional routine sampling will be conducted in areas where regular blooms have been reported, e.g., western Saginaw Bay, Maumee Bay, Sandusky Bay, etc.
Project Accomplishments
2005
Time was spent coordinating activities and development of the web site. Remote sensing imagery was provided by GLERL/Coastwatch (George Leshkevich) and NOAA (Rick Stumpf). Both of these groups provided separate imaging products for chlorophyll (phytoplankton abundance) based on their specific algorithms. The GLERL/Coastwatch imagery was based on NASA products, whereas the NOAA imagery was based on ECOHAB Gulf of Mexico products. In retrospect both of these products provided similar coverage and distribution for chlorophyll in the Great Lakes. However, chlorophyll concentrations appear to be a poor indicator of cyanobacteria blooms in the Great Lakes, particularly during summer stratification.
The field sampling part was the most intensive part of this project as several new methods were used. Sampling was conducted in Saginaw Bay, western Lake Erie, Muskegon Lake and Bear Lake on a regular basis from late May through October; approximately 30 samplings were conducted during this period. For each sampling measurements of temperature, chlorophyll, water transparency, algal abundance and composition, total phosphorus, soluble reactive phosphorus, particulate phosphorus, particulate nitrogen, particulate carbon, dissolved nitrogen, DNA, intracellular and extracellular microcystin, algal pigments, and algal photosynthetic capacity were made. Since the sampling has just been completed and most of the laboratory analysis still awaits completion, only preliminary results can be presented.
Microcystin concentrations in Saginaw Bay and western Lake Erie were low (<1 ug/L) in May and June. In July and August concentrations increased in both regions and were as high as 9 ug/l in Saginaw Bay and 4 ug/l in Lake Erie. Lower concentrations were noted in September and October.
Finally, a web page ( http://www.glerl.noaa.gov/res/Centers/HABS/habs.html) was developed that allowed the public to access the latest information on algal blooms in the Great Lakes. This web site provided basic information on algal blooms, and potential health effects, as well as the latest results of toxin concentrations associated with specific blooms. These results were generally posted within a few days of sample collection.
2004
2004 was the first year of monitoring Microcystis blooms and microcystin concentrations in Saginaw Bay and western Lake Erie. A synoptic cruise of Saginaw Bay and western Lake Erie was conducted in August 2004. Relatively high concentrations of microcystin (Figure 1) were found throughout Saginaw Bay even though little evidence of Microcystis blooms was found. Most chlorophyll concentrations in the Bay were <10 ug/l, and Secchi disk transparency averaged between 1-2 m. In western Lake Erie, where even lower chlorophyll concentrations were found, microcystin concentrations were also lower than Saginaw Bay (Figure 2, most < 1ug/l). However, one extremely high concentration of microcystin (58 ug/l) was found in the inner harbor of Put-In-Bay where surface scum of a microcystis bloom was sampled.
Figure 1. Microcystin concentrations (ug/l) in Saginaw Bay, August 2004.
Figure 2. Microcystin concentrations in western Lake Erie, August 20, 2004. Indicates station where high (58 ug/l) concentrations were found.
We examined homeostatic filtering and nutrient excretion by dreissenids using a variety of state of the art tools—including direct observation techniques developed at GLERL—at different sites in Saginaw Bay and Lake Erie. Particular emphasis was placed on the Maumee region of Lake Erie. We expected this particle rich area would represent a challenge to any methods. We measured filtering, ingestion, of C, N, and P by the mussels as well as their excretion of ammonia and phosphate, and we took sample for C:N:P ratios of the seston and algal composition.
We performed experiments at the indicated dates and sites:
Date |
Mussel species |
Site |
| 21 June 04 | Zebra mussels | Erie 6L* |
| 13 June 04 | Zebra & quagga mussels | Erie 3M ** |
| 28 July 04 | Zebra & quagga mussels | Erie 3M |
| 8 August 04 | Zebra & quagga mussels | Erie 3M |
| 23 August 04 | Zebra & quagga mussels | Saginaw Bay 5 |
| 20 September 04 | Zebra & quagga mussels | Erie 3M |
* offshore, middle of western basin
** near Maumee Bay
We captured interesting conditions with these experiments. First, we examined filtering and nutrient excretion at times when seston quality was high and very abundant at station 3M, conditions we have never sampled in our previous work. We coordinated our work with the Fahnenstiel team for Saginaw Bay Station 5 on August 23, when there was a Microcystis bloom. This was an interesting bloom in that there was much Microcystis (the “canopy species”) plus and “understory” of edible algae that appeared to be readily ingested by the mussels. We were able to simultaneously measure response of both zebra and quagga mussels in all but one experiment to see if there are cross species differences.
Products
Hong, Y., B. Biddanda, R. Rediske, A. Steinman, and G. Fahnenstiel. Occurrence of the toxin-producing cyanobacteria Cylindrospermopsis raciborskii in Mona Lake, a drowned river mouth tributary of Lake Michigan. Submitted to J. Great Lakes Res.
Last updated: 2006-08-04 mbl