Response of Aquatic Communities From a Vermont Stream to Environmentally Realistic Atrazine Exposure in Laboratory Microcosms

Gruessner, Barry; Watzin, Mary C.

doi:10.1897/1551-5028(1996)015<0410:roacfa>2.3.co;2

Cited by 11 publications

(12 citation statements)

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“…However, chronic exposures are generally lower in lotic systems, especially in higher-order streams, where peak concentrations of contaminants are diluted by increased flows but are present for longer durations. Research utilizing environmentally realistic exposures appears to show that these lower concentrations do not impair periphyton growth but can affect higher trophic levels; Gruessner and Watzin [32] found earlier emergence of benthic invertebrates in laboratory microcosms exposed to realistic atrazine concentrations.…”

Section: Chronic Exposurementioning

confidence: 99%

Chronic Effects of Atrazine on Tolerance of a Benthic Diatom

Nelson¹,

Hoagland²,

Siegfried³

1999

Environ Toxicol Chem

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The effects of prior chronic exposure to atrazine on responses to subsequent acute exposures were investigated using a common benthic diatom. Clonal, axenic cultures of Craticula cuspidata were established from the Platte River (Nebraska) and obtained from a culture collection (unlikely prior exposure to atrazine). All cultures received a chronic 67-d treatment of 1 g/L atrazine, and growth was monitored using fluorometric detection of chlorophyll a. Chronic atrazine exposure significantly reduced growth rate only during the first day of treatment (p ϭ 0.0001); no significant effect was detected throughout the remainder of the 67-d period. Following the chronic treatment, clones were exposed to six atrazine concentrations (83, 188, 402, 860, 1,782, and 3,250 g/L) to ascertain whether prior exposure influenced the tolerance of this diatom. Prior chronic exposure had a negative effect on growth following subsequent exposures to higher concentrations. A significant decline in growth was detected on days 7, 9, and 12 between previously exposed and control clones at 83 g/L of atrazine. The lack of increased tolerance in C. cuspidata after a realistic chronic exposure indicates that the levels of atrazine presently found in many lotic systems may inhibit the growth of periphyton during periods of higher pulses of atrazine characteristic of spring runoff events.

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Section: Chronic Exposurementioning

confidence: 99%

Chronic Effects of Atrazine on Tolerance of a Benthic Diatom

Nelson¹,

Hoagland²,

Siegfried³

1999

Environ Toxicol Chem

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“…However tempting, it is inappropriate to take several samples from the same microcosm sample and label these samples replicates. This is especially prevalent in artificial streams where individual sampling trays within a stream are considered replicates (Gruessner and Watzin 1996). These samples are not true replicates since each tray is connected by the water to the tray downstream.…”

Section: Data Analysis and Interpretation Of Multispecies Toxicity Testsmentioning

confidence: 99%

Design and Analysis of Multispecies Toxicity Tests for Pesticide Registration

Landis

Matthews

1997

Ecological Applications

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The community conditioning hypothesis describes ecological structures as historical, nonequilibrial, and by definition complex. Indeed, the historical nature of ecological structures is seen as the primary difference between single-species toxicity tests and multispecies test systems. Given the complex properties of ecological structures, multispecies toxicity tests need to be designed accordingly with appropriate data analysis tools. Care must be taken to ensure that each replicate shares an identical history, or divergence will rapidly occur. Attempting to realize homogeneity by linear cross inoculation or waiting for an equilibrium state to occur assumes properties that ecological structures do not have. Data analysis must also incorporate the dynamic and hyperdimensional nature of ecological structures. Univariate analysis of individual variables denies the fundamental character of ecological structures as complex systems. A variety of methods, such as correspondence analysis, nonmetric multidimensional scaling, and nonmetric clustering and association analysis, are available to search for patterns and to test their relationships to experimental treatments. Visualization techniques including Space-Time Worms and redundancy analysis are also critical in attempting to understand the dynamic nature of these structures. Reliance upon the traditional analysis methods, such as ANOVA and the estimation of LOECs (lowest observable effects concentrations) or NOECs (no observable effects concentrations), comparable to those of single-species toxicity tests, is to be blind to the unique and complex nature of multispecies toxicity tests. Fundamental design criteria for multispecies toxicity tests, data analysis, and interpretation are presented.

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“…Low atrazine concentrations (<15 μg L −1 ), for example, can have no effect [31,52] or may increase chlorophyll a (Chl a) [46] in mixed phytoplankton assemblages. Additionally, exposure of benthic algal assemblages to atrazine concentrations <77 μg L −1 [21,30,35] has been shown to have no adverse effect. Functionally, although atrazine can reduce carbon incorporation and growth rates without altering cell viability [18], it has the potential to alter the biovolume/productivity relationship.…”

Section: Introductionmentioning

confidence: 99%

Macromolecular Response of Individual Algal Cells to Nutrient and Atrazine Mixtures within Biofilms

Murdock

Wetzel

2011

Microb Ecol

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Pollutant effects on biofilm physiology are difficult to assess due to differential susceptibility of species and difficulty separating individual species for analysis. Also, measuring whole assemblage responses such as metabolism can mask species-specific responses, as some species may decrease and others increase metabolic activity. Physiological responses can add information to compositional data, and may be a more sensitive indicator of effect. It is difficult, however, to separate individual species for biochemical analyses. Agricultural runoff often contains multiple pollutants that may alter algal assemblages in receiving waters. It is unclear how mixtures containing potential algal growth stimulators and inhibitors (e.g., nutrients and herbicides) alter algal assemblage structure and function. In research presented here, algal biofilms were exposed to nutrients, atrazine, and their mixtures, and assemblage-level structural and functional changes were measured. Synchrotron infrared microspectroscopy (IMS) was used to isolate the biochemical changes within individual cells from a dominant species of a green alga (Mougeotia sp.), a diatom (Navicula sp.), and a cyanobacterium (Hapalosiphon sp.). At the assemblage level, mixtures generally increased algal biovolume, decreased chlorophyll a, and had no effect on metabolism or ammonium uptake. Navicula had a strong negative response to atrazine initially, but later was more affected by nutrients. Hapalosiphon responded positively to both atrazine and nutrients, and Mougeotia did not exhibit any biochemical trends. Generally, biochemical changes in each species were similar to cells experiencing low stress conditions, with increased relative protein and decreased relative lipid. IMS provided direct evidence that individual species in a natural biofilm can have unique responses to atrazine, nutrients, and mixtures. Results suggest that the initial benthic community composition should have a strong influence on the overall impact of agricultural pollutants.

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Response of Aquatic Communities From a Vermont Stream to Environmentally Realistic Atrazine Exposure in Laboratory Microcosms

Cited by 11 publications

References 0 publications

Chronic Effects of Atrazine on Tolerance of a Benthic Diatom

Chronic Effects of Atrazine on Tolerance of a Benthic Diatom

Design and Analysis of Multispecies Toxicity Tests for Pesticide Registration

Macromolecular Response of Individual Algal Cells to Nutrient and Atrazine Mixtures within Biofilms

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