Demonstration of toxicity to fish and to mammalian cells by Pfiesteria species: Comparison of assay methods and strains

Abstract

Toxicity and its detection in the dinoflagellate fish predatorsPfiesteria piscicida and Pfiesteria shumwayae depend on the strain and the use of reliable assays. Two assays, standardized fish bioassays (SFBs) with juvenile fish and fish microassays (FMAs) with larval fish, were compared for their utility to detect toxic Pfiesteria. The comparison included strains with confirmed toxicity, negative controls (noninducible Pfiesteria strains and a related nontoxic cryptoperidiniopsoid dinoflagellate), and P. shumwayae strain CCMP2089, which previously had been reported as nontoxic. SFBs, standardized by using toxic Pfiesteria (coupled with tests confirming Pfiesteria toxin) and conditions conducive to toxicity expression, reliably detected actively toxic Pfiesteria, but FMAs did not. Pfiesteria toxin was found in fish-and algae-fed clonal Pfiesteria cultures, including CCMP2089, but not in controls. In contrast, noninducible Pfiesteria and cryptoperidiniopsoids caused no juvenile fish mortality in SFBs even at high densities, and low larval fish mortality by physical attack in FMAs. Filtrate from toxic strains of Pfiesteria spp. in bacteria-free media was cytotoxic. Toxicity was enhanced by bacteria and other prey, especially live fish. Purified Pfiesteria toxin extract adversely affected mammalian cells as well as fish, and it caused fish death at environmentally relevant cell densities. These data show the importance of testing multiple strains when assessing the potential for toxicity at the genus or species level, using appropriate culturing techniques and assays.toxigenic dinoflagellates ͉ Pfiesteria piscicida ͉ Pfiesteria shumwayae

Comprehensive trend analysis of nutrients and related variables in a large eutrophic estuary: A decadal study of anthropogenic and climatic influences

“…Thus, CAFOs represent a relatively new nonpoint source of mammal wastes (Table 1). Most CAFOs in North Carolina, including the Neuse watershed, are in the eastern Coastal Plain near the estuaries on former wetlands (Burkholder et al 1997). The water table lies about 1 m, on average, from the surface soils; moreover, much of the land Note that prevailing winds tend to mix the waters especially toward the north shore, with the south shore relatively more protected .…”

“…The watershed also contains ϳ1.75 ϫ 10 6 swine (ϳ3.5ϫ10 6 swine produced per year, or 18% of the state's annual total, mostly in concentrated animal feed operations or CAFOs), contributing an equivalent in sewage of about 7 million people (American Society of Agricultural Engineers 1998), and ϳ4.8 ϫ 10 7 poultry produced per year (USDA 2001; Table 1). CAFOs are a recent feature on the landscape, mostly added since the late 1980s (reviewed in Burkholder et al 1997), with ϳ1.9ϫ10 7 swine produced in North Carolina per year (NC DENR 2002). Thus, CAFOs represent a relatively new nonpoint source of mammal wastes (Table 1).…”

“…previously had been ditched or tile-drained to channel runoff to receiving rivers and estuaries (Steel 1991). CAFOs release high quantities of NH 3 and other nutrient forms into the atmosphere and adjacent surface and subsurface waters (e.g., Burkholder et al 1997;Mallin 2000;Walker et al 2000).…”

“…Weather . These major storms have caused flooding of concentrated (confined) swine feed operations (CAFOs), which have occurred in high density since the late 1980s in the watershed near the upper estuary (Burkholder et al 1997). Moderate to high precipitation has also led to bypassing of raw sewage from municipal wastewater treatment plants (WWTPs); flooding of WWTPs in the aftermath of Hurricanes Fran (1996) and Floyd (1999) led to sustained treatment bypasses and the release of large amounts of raw sewage for weeks following the storms (Bales 2003).…”

Intra- and interspecies differences in growth and toxicity of Pseudo-nitzschia while using different nitrogen sources

“…Most Pseudo-nitzschia culture studies focus on P. multiseries with the results extrapolated to other species and strains (Bates 1998). However, broad species and strain differences have been well documented (Gallagher 1980, Elrifi & Turpin 1985, Goldman & Dennett 1985, Holmes et al 1991, Wood & Leatham 1992, Larsen & Bryant 1998, Burkholder et al 2005 and draw into question the validity of making conclusions about microalgal species physiology based on one or a few strains.…”