ABSTRACT
Two anthelmintic macrocyclic lactones-ivermectin and moxidectin-have revolutionized parasite control in cattle. These drugs are only partly metabolized by livestock, and the main route of excretion is via feces. In seasonally inundated floodplains, cattle feces come into direct contact with surface water. Important differences in pharmacokinetics and pharmacodynamics between these drugs may bear on their ecotoxicology in aquatic ecosystems. Moxidectin strongly binds to organic matter and thereby may be consumed in aquatic food webs, but there is a scarcity of data on toxicity to freshwater invertebrates. The objectives of this work were to determine the effect of moxidectin spiked in cattle dung on survival and growth of three representative aquatic invertebrates: the zooplankton Ceriodaphnia dubia, the amphipod Hyalella curvispina, and the snail Pomacea canaliculata. Moxidectin-laced dung was added in microcosms and concentrations were measured in water, sediment + dung, roots of the aquatic plant Salvinia biloba, and the aforementioned invertebrates. The influence of moxidectin on nutrient concentrations was also evaluated. Dung was spiked with moxidectin to attain concentrations of 750, 375 and 250 µg kg-1 dung fresh weight, approximating those found in cattle dung at days 2, 3, and 5 following subcutaneous injection. Concentrations of moxidectin in dung during the first week of excretion were lethally toxic for the tested invertebrate taxa. The persistence of moxidectin in the sediment + dung and the uptake of the drug in roots of S. biloba increase its potential exposure to aquatic food webs. Moxidectin also reduced the rate of release of soluble reactive phosphorus to the water.
Subject(s)
Antiparasitic Agents/toxicity , Invertebrates/drug effects , Macrolides/toxicity , Veterinary Drugs/toxicity , Zooplankton/drug effects , Amphipoda/drug effects , Animals , Antiparasitic Agents/analysis , Cattle , Daphnia/drug effects , Ecotoxicology/methods , Feces/chemistry , Fresh Water , Geologic Sediments , Macrolides/analysis , Snails/drug effects , Veterinary Drugs/analysis , Water Pollutants, Chemical/toxicityABSTRACT
Ivermectin (IVM) is a parasiticide widely used for livestock. It is a semisynthetic derivative of avermectin, a macrocyclic lactone produced by Streptomyces avermitilis. This drug is only partly metabolized by livestock; considerable amounts of parent drug are excreted mostly via feces. To simulate exposure of aquatic invertebrates and macrophytes to direct excretion of cattle dung into surface waters, a microcosm experiment with IVM spiked in cattle dung was conducted. The objectives of this study were to characterize accumulation of IVM in water, sediment+dung, roots of the floating fern Salvinia and the zooplankton Ceriodaphnia dubia, the amphipod Hyalella and the apple snail Pomacea; to determine the effect of this drug spiked in cattle dung on life-history traits of these invertebrates; and to evaluate the influence of IVM on aquatic nutrient cycling. Dung was spiked with IVM to attain concentrations of 1150, 458, 50 and 22µgkg-1dung fresh weight, approximating those found in cattle dung at days 3, 7, 16 and 29 following subcutaneous injection. Concentrations found in dung during the first week of excretion were lethally toxic to Ceriodaphnia dubia and Hyalella, whereas no mortality was observed in Pomacea. Concentrations of IVM in roots, sediment + dung and Pomacea increased significantly from the lowest to the highest treatment level. The effect of this drug on decomposition and release of nutrients from dung would have negative consequences for nutrient cycling in water. Increasing concentrations in sediment + dung with days of the experiment suggested that toxic concentrations would persist for an extended period in the water-sediment system. IVM represents an ecological risk for aquatic ecosystems, underscoring the need for livestock management strategies to limit its entry into water bodies.
Subject(s)
Antiparasitic Agents/toxicity , Aquatic Organisms/drug effects , Feces/chemistry , Ivermectin/toxicity , Water Pollutants, Chemical/toxicity , Animals , Antiparasitic Agents/analysis , Cattle , Fresh Water/chemistry , Geologic Sediments/chemistry , Ivermectin/analysis , Livestock , Models, Theoretical , Water Pollutants, Chemical/analysisABSTRACT
We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem.
Subject(s)
Ecosystem , Trees/classification , Argentina , RiversABSTRACT
Floristic composition and distribution of the Andean subtropical riparian forests of Lules River, Tucuman, Argentina. We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem. Rev. Biol. Trop. 58 (1): 499-510. Epub 2010 March 01.
Se estudió la composición florística y distribución de los bosques ribereños de dos sistemas hidrográficos en una región subtropical andina. Utilizando técnicas uni y multivariadas, se probó la hipótesis que existe un bosque ribereño diferenciable, compuesto por vegetación nativa típica de la provincia fitogeográfica de Yungas, y que la distribución de la vegetación varió significativamente con las características geomorfológicas. Transectos paralelos a lo largo de los cursos de agua se utilizaron para recolectar los datos de presencia-ausencia de vegetación en once sitios. El Análisis de Correspondencia definió un grupo de especies ribereñas común para el área estudiada (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium y Eugenia uniflora) e identificó dos sitios de referencia. La distribución de la vegetación ribereña varió significativamente con las características geomorfológicas a lo largo de los sitios estudiados. Los hábitats ribereños estuvieron compuestos por especies nativas y exóticas. Una flora ribereña distintiva, diferente en estructura y función a la vegetación terrestre adyacente, no pudo ser identificada. Especies ribereñas fueron similares a los estratos terrestres adyacentes. Estas especies no estarían limitadas por la proximidad al río. Impactos antropogénicos fueron factores importantes que regulan la introducción y el incremento de la vegetación exótica. La falta de regulación de algunas actividades en la zona podría causar problemas graves en la integridad de este ecosistema.
