Distribution of Benthic Flora in the Lower Course of the Valdivia River, Chile

Ramírez, Carlos; Figueroa, Heriberto; Hauenstein, Enrique; Contreras, Domingo

doi:10.2307/1351502

“…In contrast, enriched δ 13 C DIC in the Rapel and Valdivia basins suggest that marine photosynthetically fixed carbon may significantly influence the δ 13 C DIC [ Dubois et al , ; Schulte et al , ]. The sampling station at the Valdivia River mouth corresponds to an estuarine system, which is typically characterized by a high phytoplanktonic biomass [ Aguilera et al , ; Ramírez et al , ]. Although photosynthesis:respiration (P:R) ratio was not measured in the present study, a low P:R ratio is characteristic of most estuarine systems [e.g., Battin et al , ; Bauer and Bianchi , ; Borges , ; Brunet et al , ; Cole and Caraco , ], which indeed the enrich δ 13 C DIC values by introducing additional CO 2 that results from respiration of riverine and marine photosynthetically fixed carbon and allochthonous DOC‐POC.…”

Section: Discussionmentioning

confidence: 74%

Influence of climate and land use in carbon biogeochemistry in lower reaches of rivers in central southern Chile: Implications for the carbonate system in river‐influenced rocky shore environments

Pérez

¹

,

DeGrandpre

²

,

Lagos

³

et al. 2015

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Freshwater discharge affects the biogeochemistry of river-influenced nearshore environments by contributing with carbon and nutrients. An increase in human activities in river basins may alter the natural riverine nutrients and carbon export to coastal ecosystems. Along a wide latitudinal range (32°55′S-40°10′S), this study explores the role of climate and land use in determining the nutrient and carbon concentrations in the river mouth and fluxes to adjacent coastal areas. Between winter 2011 and fall 2012, we collected monthly samples in five river mouths in central southern Chile and at rocky shore sites affected by river plumes. Basins were characterized by different land uses and meteorological conditions along this latitudinal range. Water samples were collected for pH measurements, nutrients, dissolved organic and inorganic carbon, particulate organic carbon, and isotopic signatures (δ 13 C). Our results show a north-south gradient in concentrations of nutrients and carbon. The highest concentrations were observed in the Maipo basin, which presents the highest percentage of urban-industrial activities. Nutrients and carbon contributions, in most cases, were lowest in the southern Valdivia basin, which has the least human intervention and a greater percentage of vegetation. The Biobío River had the highest nutrient and carbon fluxes, in most cases, due to its high river discharge. Our results show the influence of river plume effects on carbon and nitrogen concentrations in river-influenced rocky shore sites. Moreover, our study suggests that land use might influence some parameters of carbonate system in rivers and river-influenced rocky shore environments. River-influenced rocky shore environments may exhibit suppression in aragonite saturation state with implications for calcifiers inhabiting these marine environments.

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“…The aquatic plant E. densa is an invasive waterweed originally from Brazil and thought to have been introduced in the area of Valdivia around 1908 [13]. It corresponds to a fast‐growing plant that propagates both sexually and through vegetative fractionation, and it also is capable of undergoing important seasonal changes in morphology and relative size [14].…”

Section: Methodsmentioning

confidence: 99%

Effect of prolonged exposition to pulp mill effluents on the invasive aquatic plant Egeria densa and other primary producers: A mesocosm approach

Palma

¹

,

Silva

²

,

Muñoz

³

et al. 2008

Enviro Toxic and Chemistry

7

0

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The recent disappearance of the aquatic plant Egeria densa, a Brazilian native invasive species, from a wetland in southern Chile prompted several efforts to unveil the origin of this phenomenon. Because these changes occurred by the time a newly built pulp mill started its operations in the area, a reasonable doubt for a cause-effect relationship is plausible. We implemented a mesocosm approach to directly evaluate the effect of treated pulp mill effluents (PMEs) on several growth-related parameters of E. densa as well as other primary producers. We hypothesize that effluent, at a dilution similar to that detected in the zone of the wetland where the negative environmental impacts were evident, has a significant negative effect on this aquatic plant as well as on other primary producers inside a mesocosm system. After a prolonged (months) exposure to both 0% PME with pure river water and a 4 to 5% (v/v) dilution of treated PME, no effect on E. densa was measured. Furthermore, plants exposed to effluent exhibited a significantly greater general growth rate. Coincidently, chlorophyll a concentration in the water column and periphyton biomass also changed over time, but without any pattern attributable to the effluent. Values of the autotrophic index obtained from the periphyton growth pattern did not suggest enrichment of the system with organic matter. Our results only refer to the direct effect of mill effluents on several biotic responses, but they represent an important advance toward generation of the scientific knowledge necessary to understand how the ecosystem functions while receiving this and other unquantified sources of water.

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“…The aquatic plant E. densa is an invasive waterweed originally from Brazil and thought to have been introduced in the area of Valdivia around 1908 [13]. It corresponds to a fastgrowing plant that propagates both sexually and through vegetative fractionation, and it also is capable of undergoing important seasonal changes in morphology and relative size [14].…”

Section: Study Organisms and Biological Quantifications: Primary Prodmentioning

confidence: 99%

Effect of Prolonged Exposition to Pulp Mill Effluents on the Invasive Aquatic Plant Egeria Densa and Other Primary Producers: A Mesocosm Approach

Palma¹,

Silva²,

Muñoz³

et al. 2007

Environ Toxicol Chem

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The recent disappearance of the aquatic plant Egeria densa, a Brazilian native invasive species, from a wetland in southern Chile prompted several efforts to unveil the origin of this phenomenon. Because these changes occurred by the time a newly built pulp mill started its operations in the area, a reasonable doubt for a cause-effect relationship is plausible. We implemented a mesocosm approach to directly evaluate the effect of treated pulp mill effluents (PMEs) on several growth-related parameters of E. densa as well as other primary producers. We hypothesize that effluent, at a dilution similar to that detected in the zone of the wetland where the negative environmental impacts were evident, has a significant negative effect on this aquatic plant as well as on other primary producers inside a mesocosm system. After a prolonged (months) exposure to both 0% PME with pure river water and a 4 to 5% (v/v) dilution of treated PME, no effect on E. densa was measured. Furthermore, plants exposed to effluent exhibited a significantly greater general growth rate. Coincidently, chlorophyll a concentration in the water column and periphyton biomass also changed over time, but without any pattern attributable to the effluent. Values of the autotrophic index obtained from the periphyton growth pattern did not suggest enrichment of the system with organic matter. Our results only refer to the direct effect of mill effluents on several biotic responses, but they represent an important advance toward generation of the scientific knowledge necessary to understand how the ecosystem functions while receiving this and other unquantified sources of water.

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Distribution of Benthic Flora in the Lower Course of the Valdivia River, Chile

Cited by 6 publications

References 11 publications

Influence of climate and land use in carbon biogeochemistry in lower reaches of rivers in central southern Chile: Implications for the carbonate system in river‐influenced rocky shore environments

Influence of climate and land use in carbon biogeochemistry in lower reaches of rivers in central southern Chile: Implications for the carbonate system in river‐influenced rocky shore environments

Effect of prolonged exposition to pulp mill effluents on the invasive aquatic plant Egeria densa and other primary producers: A mesocosm approach

Effect of Prolonged Exposition to Pulp Mill Effluents on the Invasive Aquatic Plant Egeria Densa and Other Primary Producers: A Mesocosm Approach

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