No abstract

Environmental factors associated with the occurrence of toxic cyanobacterial blooms and toxin production were investigated during the summers of 1994 and 1995 in Steilacoom Lake, Washington. A pronounced and prolonged toxic bloom of Microcystis aeruginosa occurred during summer 1994 but not during 1995. Lake characteristics that were associated with the toxic bloom in 1994 were higher total phosphorus, decreased water transparency, high water column stability, high surface water temperature and pH, and decreased lake flushing. Decreased water transparency during 1994 may have been due to significantly lower zooplankton abundance. We hypothesize that this decreased transparency was caused by increased planktivory by higher numbers of coho salmon (Oncorhynchus kisutch) fingerlings during 1994 and (or) inhibition of zooplankton grazing by Microcystis. The success of Microcystis over other cyanobacteria was associated with low nitrogen to phosphorus ratios and low nitrate-nitrogen with sufficient ammonium-nitrogen concentrations. Toxin production (i.e., micrograms of microcystin per gram of plankton biomass) was not constant over the duration of detectable toxicity; hence, no relationship was found between Microcystis abundance and microcystin concentration. However, microcystin concentration was positively correlated with increasing soluble reactive phosphorus concentrations between 1 and 10 µg·L-1, indicating that toxin production may have been limited by phosphorus.

No abstract

The more frequent occurrence of both marine and freshwater toxic algal blooms and recent problems with new toxic events have increased the risk for illness and negatively impacted sustainable public access to safe shellfish and recreational waters in Washington State. Marine toxins that affect safe shellfish harvest in the state are the saxitoxins that cause paralytic shellfish poisoning (PSP), domoic acid that causes amnesic shellfish poisoning (ASP) and the first ever US closure in 2011 due to diarrhetic shellfish toxins that cause diarrhetic shellfish poisoning (DSP). Likewise, the freshwater toxins microcystins, anatoxin-a, cylindrospermopsins, and saxitoxins have been measured in state lakes, although cylindrospermopsins have not yet been measured above state regulatory guidance levels. This increased incidence of harmful algal blooms (HABs) has necessitated the partnering of state regulatory programs with citizen and user-fee sponsored monitoring efforts such as SoundToxins, the Olympic Region Harmful Algal Bloom (ORHAB) partnership and the state’s freshwater harmful algal bloom passive (opportunistic) surveillance program that allow citizens to share their observations with scientists. Through such integrated programs that provide an effective interface between formalized state and federal programs and observations by the general public, county staff and trained citizen volunteers, the best possible early warning systems can be instituted for surveillance of known HABs, as well as for the reporting and diagnosis of unusual events that may impact the future health of oceans, lakes, wildlife, and humans.

No abstract

Ingestion of water contaminated with the cyanotoxin, microcystin (MC), can pose serious health risks to humans. MC is also known to accumulate in seafood; however, this exposure pathway is much less understood. A fundamental element of this uncertainty is related to analytical difficulties. Commercially available enzyme-linked immunosorbent assays (ELISAs) offer one of the best options for routine MC detection, but methods of detecting MC in tissue are far from standardized. We spiked freshwater finfish and marine mussel tissues with MC, then compared recovery rates using four different preparation protocols and two ELISA types (polyclonal anti-MC-ADDA/direct monoclonal (DM)). Preparation protocol, type of ELISA, and seafood tissue variety significantly affected MC detection. This is the first known study to use DM ELISA for tissue analyses, and our findings demonstrate that DM ELISA combined with a short solvent extraction results in fewer false positives than other commonly used methods. This method can be used for rapid and reliable MC detection in seafood.

Inorganic nitrogen and phosphorus were applied weekly during the growing season from 1980 to 1982 and twice weekly in 1983 to Hobiton Lake, a warm monomictic coastal lake in British Columbia. The lake was not fertilized in 1984. Average numbers of bacteria during the growing season decreased from a high of 1.53 × 106∙mL−1 in the fertilized condition to 0.84 × 106∙mL−1 in the unfertilized condition. Chlorophyll a concentrations decreased from a maximum seasonal average of 2.69 μg∙L−1 (1981) to 1.30 μg∙L−1 (1984), and algal numbers decreased from 5.83 × 104∙mL−1 (1983) to 2.29 × 104∙mL−1 (1984). Although the numbers of phytoplankton in each size fraction (picoplankton, nanoplankton, or microplankton) decreased in the unfertilized condition, the greatest change was an almost fourfold decrease in picoplankton, which consisted of 90% cyanobacteria (primarily Synechococcus spp.). Abundance of the large diatoms Rhizosolenia spp. and Melosira spp. increased in 1984, resulting in an increase in average seasonal algal volume. Average densities of medium (0.15–0.84 mm) and large (0.85–1.5 mm) zooplankton were greatest in 1982, while rotifers and small zooplankton (0.10–0.14 mm) were most dense in 1984 following nutrient reduction. The lake had relatively high concentrations of planktivorous juvenile sockeye salmon (Oncorhynchus nerka) that appeared to minimize any direct effect of nutrient additions on zooplankton densities.

Until recently, exposure pathways of concern for cyanotoxins have focused on recreational exposure, drinking water, and dermal contact. Exposure to cyanotoxins through fish consumption is a relatively new area of investigation. To address this concern, microcystins and other cyanotoxins were analyzed in fish collected from nine Washington lakes with recurrent toxic blooms using two types of enzyme-linked immunosorbent assays (ELISAs) and liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS). Microcystins or microcystin-like compounds were elevated in fish liver relative to muscle and other tissues (liver>gut>muscle). Microcystin concentrations in fish fillet samples using anti-Adda ELISA (range 6.3-11 μg/kg wet weight) were consistently higher in all fish species than concentrations using anti-microcystin (MC)-leucine-arginine (LR) ELISA (range 0.25-2.4 μg/kg wet weight). MC-leucine-alanine (LA) was the only variant detected in fish (2.5-12 μg/kg in four livers) among the nine variants analyzed by LC-MS/MS. Fish fillets showed no accumulation of the MCs targeted by LC-MS/MS. Other cyanotoxins analyzed (anatoxin-a, saxitoxin, domoic acid, and okadaic acid) were not detected in fish. Based on this and evidence from other studies, we believe that people can safely consume two 8-oz fish fillet meals per week from lakes with blooms producing MCs (clean the fish and discard viscera).