Ecotoxic effects of atrazine on aquatic macroinvertebrates and its impact on ecosystem structure
Huggins, DG
| HERO ID | 11145476 |
|---|---|
| Year | 1990 |
| Title | Ecotoxic effects of atrazine on aquatic macroinvertebrates and its impact on ecosystem structure |
| Authors | Huggins, DG |
| City | Lawrence, KS |
| Abstract | The ecotoxic effects of atrazine on macroinvertebrates and ecosystem structure were evaluate in eight experimental pond mesocosms (0.045 ha) after 805 days of continuous exposure at four nominal concentrations (zero, 20, 100 and 500 µg/L). Organismal, population, community and ecosystem variables, some of which represented antecedent conditions (e.g. submergent macrophyte abundances) were analyzed to determine occurrence of positive and/or negative ecotoxic effects. In most instances the direct and indirect effects of atrazine exposure on various ecosystem variables were verified with a linear structural modelling technique, path analysis. The growth and survivorship of various instar classes for two midge species (Chironomidae: Diptera), Endochironomus nigricans and Dicrotendipes cf. simponi, were shown to respond differently (positive vs. negative effects) to atrazine exposure when compared to reference ponds. Eleven of 15 taxa displayed abundance responses due to atrazine concentrations. The scud Hyallela azteca and the midge Dicrotendipes cf. simsoni populations in atrazine dosed ponds were noted to increase. Other taxa abundances showed negative ecotoxic effects or varied responses depending on temporal or spatial conditions. Macro invertebrate community attributes were observed to be variously affected by exposure which were related to both concentration level and/or date. Macroinvertebrate richness and abundance were suppressed at all atrazine treatment concentrations during the spring but later recovered with abundance values being significantly higher in 20 µg/L ponds. Macroinvertebrate diversity responded variously to atrazine treatments but typically displayed negative ecotoxic effects. The abundance of macroinvertebrate herbivores and epiphytes was often negatively affected by atrazine concentration as low as 20 µg/L while omnivore populations increased in atrazine treated ponds. Other habitat and trophic guild categories showed occasional effects due to atrazine exposure. The abundance of macroinvertebrate "generalists" and "specialists" were observed to respond differently to atrazine treatments. Specialist populations ere generally highest in 20 µg/L ponds while generalists were most abundant in 500 µg/L ponds. Multiple regression models for macroinvertebrate, phytoplankton, zooplankton, fish, water chemistry and other ecosystem variables seldom identified atrazine as an independent variable. When included in a model, atrazine concentrations explained only limited amounts of the variance in the dependent variable. Important independent variable common to most regression models were: macrophyte abundance: pH, total alkalinity, turbidity and oxygen saturation: chlorophyll a: pond depth: and presence or absence of Grass Carp (Cienopharyngodon idella). The ecosystem structure of ponds was defined by path diagrams that identified the occurrence of both direct and indirect effects on nearly all endogenous model factors as a result of three exogenous variables. These exogenous variables were pond depth, presence or absence of Grass Carp and atrazine concentration in water. |
| Url | https://biosurvey.ku.edu/pub/ecotoxic-effects-atrazine-aquatic-macroinvertebrates-and-its-impact-ecosystem-structure |
| Is Certified Translation | No |
| Dupe Override | No |
| University Name | University of Kansas |
| Paper Level | Doctoral Dissertation |
| Is Public | Yes |
| Language Text | English |