Recent anthropogenic climate change and the exponential increase over the past few decades of Saharan dust deposition, containing ecologically important inputs of phosphorus (P) and calcium (Ca), are potentially affecting remote aquatic ecosystems. In this study, we examine changes in cladoceran assemblage composition and chlorophyll-a concentrations over the past~150 years from high-resolution, welldated sediment cores retrieved from six remote high mountain lakes in the Sierra Nevada Mountains of Southern Spain, a region affected by Saharan dust deposition.In each lake, marked shifts in cladoceran assemblages and chlorophyll-a concentrations in recent decades indicate a regional-scale response to climate and Saharan dust deposition. Chlorophyll-a concentrations have increased since the 1970s, consistent with a response to rising air temperatures and the intensification of atmospheric deposition of Saharan P. Similar shifts in cladoceran taxa across lakes began over a century ago, but have intensified over the past~50 years, concurrent with trends in regional air temperature, precipitation, and increased Saharan dust deposition. An abrupt increase in the relative abundance of the benthic cladoceran Alona quadrangularis at the expense of Chydorus sphaericus, and a significant increase in Daphnia pulex gr. was a common trend in these softwater lakes. Differences in the magnitude and timing of these changes are likely due to catchment and lake-specific differences. In contrast with other alpine lakes that are often affected by acid deposition, atmospheric Ca deposition appears to be a significant explanatory factor, among others, for the changes in the lake biota of Sierra Nevada that has not been previously considered. The effects observed in Sierra Nevada are likely occurring in other Mediterranean lake districts, especially in softwater, oligotrophic lakes. The predicted increases in global temperature and Saharan dust deposition in the future will further impact the ecological condition of these ecosystems.

Ecosystem responses to climate-related changes in a Mediterranean alpine environment over the last ~180 years. Ecosystems, 22(3), pp. 563-577.

No abstract

Daphnia is a good model organism for studying factors affecting dispersal and patterns of genetic diversity. Within this genus, the Daphnia pulex species complex includes lineages from North America and Europe, with some considered invaders in various continents, although their colonization history is poorly known. We used mitochondrial DNA and microsatellite markers to identify the D. pulex complex lineages in Sierra Nevada, determine their reproductive mode and reconstruct their genetic history (over the past ~25 to 65 years). We present the first recording of North American (NA) D. cf. pulex in a European high-mountain lake, showing its arrival ~65 years ago in lake Borreguil without temporal changes in its genetic structure. European (Eu) D. cf. pulicaria is the only lineage present in other Sierra Nevada lakes and also showed no genetic change over time. The results for both species are congruent with obligate parthenogenetic reproduction mode. Moreover, water mineralization may influence the clonal distribution of the D. pulex complex in Sierra Nevada, without ruling out dispersal limitation and/or founder effects. Although NA D. cf. pulex had not spread to other Sierra Nevada lakes, it could threaten Eu D. cf. pulicaria in Sierra Nevada and other European alpine lakes.

Abstract. Alpine ecosystems of the southern Iberian Peninsula are among the most vulnerable and the first to respond to modern climate change in southwestern Europe. While major environmental shifts have occurred over the last ∼1500 years in these alpine ecosystems, only changes in the recent centuries have led to abrupt environmental responses, but factors imposing the strongest stress have been unclear until now. To understand these environmental responses, this study, for the first time, has calibrated an algal lipid-derived temperature proxy (based on long-chain alkyl diols) to instrumental historical data extending alpine temperature reconstructions to 1500 years before present. These novel results highlight the enhanced effect of greenhouse gases on alpine temperatures during the last ∼200 years and the long-term modulating role of solar forcing. This study also shows that the warming rate during the 20th century (∼0.18 ∘C per decade) was double that of the last stages of the Little Ice Age (∼0.09 ∘C per decade), even exceeding temperature trends of the high-altitude Alps during the 20th century. As a consequence, temperature exceeded the preindustrial record in the 1950s, and it has been one of the major forcing processes of the recent enhanced change in these alpine ecosystems from southern Iberia since then. Nevertheless, other factors reducing the snow and ice albedo (e.g., atmospheric deposition) may have influenced local glacier loss, since almost steady climate conditions predominated from the middle 19th century to the first decades of the 20th century.