ABSTRACT Changes in rainfall patterns caused by anthropogenic global climate change or planetary-... more ABSTRACT Changes in rainfall patterns caused by anthropogenic global climate change or planetary-scale events, such as the El Nino Southern Oscillation, can significantly affect the abundance and distribution of organisms. Despite the evidence of such effects on marine and terrestrial systems, ecological consequences of rainfall fluctuations in coastal marine ecosystems remain poorly understood. Here we evaluate the effects of rainfall intensity on the interaction between the cordgrass Spartina densiflora and Azara's grass mouse Akodon azarae in a southwestern Atlantic salt marsh (Mar Chiquita coastal lagoon, Argentina). Field surveys showed that the abundance of A. azarae increased during rainy summers (i.e. El Nino 2005 and 2007) and had lowest values during dry summers (i.e. La Nina 2008). Salt content in sediment and plant tissue were negatively related with rainfall. In addition, field experiments showed that increased sediment salinity resulted in increased salt content in plant tissues. Elevated soil salinity also increased the proportion of senescent S. densiflora tissues and reduced plant growth. The consumption of S. densiflora leaves by A. azarae also decreased with increased soil salinity. The proportion of S. densiflora in feces collected during the driest summer was very small. Therefore, changes in the abundance of A. azarae could be mediated by plant-rodent trophic interaction or by plant cover changes. In conclusion, rainfall fluctuations changed the abiotic environment (i.e. salinity), decreasing primary production and indirectly modifying habitat use by the omnivore A. azarae and its trophic interaction with S. densiflora. The present study provides evidence that rainfall can modify ecological processes that affect the structure and dynamics of coastal marine ecosystems.
Page 1. Joint control by rodent herbivory and nutrient availability of plant diversity in a salt ... more Page 1. Joint control by rodent herbivory and nutrient availability of plant diversity in a salt marshsalty steppe transition zone Juan Alberti, Alejandro Canepuccia, Jesu´ s Pascual, Claudio P ´erez & Oscar Iribarne Keywords ...
... Despite the high degree of foraging specialization, supported by low values of Levin&#x27... more ... Despite the high degree of foraging specialization, supported by low values of Levin's trophic ... Murdoch 1969) and opportunistically prey upon locally abundant resources to supplement its typical diet. ... were the main food item of O. geoffroyi, followed by small rodents (Johnson ...
Journal of Experimental Marine Biology and Ecology, 2011
After intense debate it is now accepted that nutrients (a bottom-up process) and herbivores (a to... more After intense debate it is now accepted that nutrients (a bottom-up process) and herbivores (a top-down process) are both important controls of plant productivity in many systems. Besides their direct effects, herbivores may also have profound positive or negative indirect effects that can be modulated by nutrients and time. The interactive relationships between time, nutrient availability and herbivore impacts (direct
ABSTRACT Changes in rainfall patterns caused by anthropogenic global climate change or planetary-... more ABSTRACT Changes in rainfall patterns caused by anthropogenic global climate change or planetary-scale events, such as the El Nino Southern Oscillation, can significantly affect the abundance and distribution of organisms. Despite the evidence of such effects on marine and terrestrial systems, ecological consequences of rainfall fluctuations in coastal marine ecosystems remain poorly understood. Here we evaluate the effects of rainfall intensity on the interaction between the cordgrass Spartina densiflora and Azara's grass mouse Akodon azarae in a southwestern Atlantic salt marsh (Mar Chiquita coastal lagoon, Argentina). Field surveys showed that the abundance of A. azarae increased during rainy summers (i.e. El Nino 2005 and 2007) and had lowest values during dry summers (i.e. La Nina 2008). Salt content in sediment and plant tissue were negatively related with rainfall. In addition, field experiments showed that increased sediment salinity resulted in increased salt content in plant tissues. Elevated soil salinity also increased the proportion of senescent S. densiflora tissues and reduced plant growth. The consumption of S. densiflora leaves by A. azarae also decreased with increased soil salinity. The proportion of S. densiflora in feces collected during the driest summer was very small. Therefore, changes in the abundance of A. azarae could be mediated by plant-rodent trophic interaction or by plant cover changes. In conclusion, rainfall fluctuations changed the abiotic environment (i.e. salinity), decreasing primary production and indirectly modifying habitat use by the omnivore A. azarae and its trophic interaction with S. densiflora. The present study provides evidence that rainfall can modify ecological processes that affect the structure and dynamics of coastal marine ecosystems.
Page 1. Joint control by rodent herbivory and nutrient availability of plant diversity in a salt ... more Page 1. Joint control by rodent herbivory and nutrient availability of plant diversity in a salt marshsalty steppe transition zone Juan Alberti, Alejandro Canepuccia, Jesu´ s Pascual, Claudio P ´erez & Oscar Iribarne Keywords ...
... Despite the high degree of foraging specialization, supported by low values of Levin&#x27... more ... Despite the high degree of foraging specialization, supported by low values of Levin's trophic ... Murdoch 1969) and opportunistically prey upon locally abundant resources to supplement its typical diet. ... were the main food item of O. geoffroyi, followed by small rodents (Johnson ...
Journal of Experimental Marine Biology and Ecology, 2011
After intense debate it is now accepted that nutrients (a bottom-up process) and herbivores (a to... more After intense debate it is now accepted that nutrients (a bottom-up process) and herbivores (a top-down process) are both important controls of plant productivity in many systems. Besides their direct effects, herbivores may also have profound positive or negative indirect effects that can be modulated by nutrients and time. The interactive relationships between time, nutrient availability and herbivore impacts (direct
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