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To determine the effects of anthropogenic pressures on the ecology of rivers in the Segura Watershed, we examined stream physicochemistry and the macroinvertebrate community in relation to land use, flow regulation by reservoirs, and the Tajo‐Segura Inter‐basin Transfer. The inter‐basin transfer is thought to be the most important stressor because it affects the flow regime as well as water quality and quantity in an arid, typically water‐stressed environment. The concentrations of major ions were strongly impacted by agricultural and urban land uses and the inter‐basin transfer. There was a significant increase in conductivity and the concentrations of SO42− and other major ions downstream of the Tajo‐Segura Transfer. The macroinvertebrate community was less diverse and composed of more pollution‐tolerant taxa in areas affected by flow regulation and the inter‐basin transfer. The rivers of study are at risk for salinization because of inputs from land use and the Tajo‐Segura Transfer. Therefore, major ion and nutrient concentrations should be monitored. Currently, there is no limit specified for SO42− concentration in relation to aquatic ecosystem health in Spain. Measures are needed to reduce the effects of contamination and flow regulation to protect the aquatic ecosystem within the Segura Watershed. Copyright © 2012 John Wiley & Sons, Ltd.

1 Globalization leads to the introduction of invasive species that are often accompanied by associated microorganisms, and this can lead to homogenization of both introduced hosts and microbes with the native biota. One such example is the invasive Eurasian woodwasp Sirex noctilio, which inoculates pines with an obligate nutritional mutualist, the white rot fungus Amylostereum areolatum. 2 Although S. noctilio has been previously introduced outside of its native range, its arrival in North America was the first time that it was introduced to communities hosting native Sirex species and Amylostereum strains. 3 We conducted experiments aiming to investigate acceptance versus avoidance of native and non-native Amylostereum strains and species during ovipositor drilling by females of S. noctilio and a native congener, Sirex nigricornis. 4 Sirex noctilio preferred wood without prior fungal emplacement, whereas S. nigricornis preferred wood inoculated with one of the strains of Amylostereum that putatively invaded with S. noctilio. 5 Drilling and presumed oviposition by both woodwasp species were highly aggregated. 6 Based on the responses of these two Sirex species to the fungal strains and species included in the present study, the invasive S. noctilio would continue its present symbiont associations, whereas the native S. nigricornis would partly use the strain of fungal symbiont putatively introduced with S. noctilio.

As temperatures rise and precipitation patterns change, approaches are needed for early detection of the effects on ecosystems. Macroinvertebrate data collected from 81 sites with multiple habitat kick sampling were compiled for this study. We used a binary logistic regression model to predict the probability of local extinction or range expansion of aquatic macroinvertebrates with changes in temperature and precipitation in watersheds of Castilla-La Mancha, Spain. Aquatic insect families from the following orders were found to be sensitive to an increase in average spring temperatures: Ephemeroptera, Plecoptera, Megaloptera, Trichoptera, Coleoptera and Diptera. Taxa in Ephemeroptera, Trichoptera, Hemiptera and Coleoptera showed negative relationships with minimum (winter) temperature, maximum spring temperature and/ or precipitation. One mayfly, Caenis, exhibited a positive relationship with minimum temperature. These results indicate that these aquatic communities are expected to change significantly in the short-term, with the potential to alter stream ecosystem functioning. Mediterranean ecosystems are considered biodiversity hotspots, and biotic communities in freshwater habitats in these areas may be particularly vulnerable to projected increases in temperature and decreases in precipitation. The ability of taxa to withstand these changes will depend on resistance, resilience and dispersal capabilities of the aquatic macroinvertebrates as well as available habitat.