ABSTRACT Sedimentary photosynthetic pigments as indicators of climate and watershed perturbations in an alpine lake in southern Spain A short core was collected in Río Seco Lake, an alpine and oligotrophic lake located in the Sierra Nevada Mountains (in the southeast region of Spain) to determine the algal group changes over the past 200 years. In particular, it was analysed for fossil pigments and their derivatives and the geochemical (C/N ratio, grain-size analyses and isotopic dating) and climatic (temperature and rainfall values obtained from a long instrumental series) variables. The main pigments were carotenoids that indicate cyanobacteria (zeaxanthin, echinenone and myxoxanthophyll), diatoms and chrysophytes (fucoxanthin and diadinoxanthin) and green algae (lutein). The changes in pigment abundance over time were mainly explained by the temperature. Zeaxanthin showed a marked decrease from the 19 th century to the present and is attributed to picoplanktonic cyanobacteria in Río Seco Lake. This decrease may result from climate-driven factors affecting herbivorous grazing pressure and water residence time. The increasing human activity around the lake likely generated a high input of carotenoid-poor pigmented organic matter and led to the dilution of chlorophylls and labile carotenoids observed over recent decades. Key words: Paleolimnology, sedimentary pigments, HPLC, alpine lake, Sierra Nevada. RESUMEN Pigmentos fotosintéticos sedimentarios como indicadores de perturbaciones climáticas y de la cuenca en un lago alpino del sudeste de España Se tomó un testigo corto de sedimento de la laguna de Río Seco, un lago alpino y oligotrófico localizado en Sierra Nevada (sudeste de España) para determinar los cambios en la comunidad algal de los últimos 200 años. Se analizaron pigmentos fósiles y sus derivados, variables geoquímicas (índice C/N, análisis granulométrico e isótopos de datación) y variables climáticas (valores de temperatura y precipitación procedentes de series instrumentales extensas). Los principales pigmentos analizados fueron carotenoides indicadores de cianobacterias (zeaxantina, equinona y mixoxantofila), diatomeas y crisofíceas (fucoxantina y diadinoxantina) y algas verdes (luteína

Abstract – Complete inventories of the fauna at a given place, for a specific community or geographical area are often exceedingly hard to get. In recent years a number of estimation techniques have emerged that can be used to extrapolate from these samples to the true number of species in an area. These estimation models are based on different mathematical approaches and can be classified as either species accumulation curves or nonparametric estimators (Brose et al., 2003, Ecology, 84, 2364–2377). In this paper, we have tested the performance of some of the richness estimators on nineteen mountain ponds in Castilla y León (Spain) in order to provide guidance on their potential use in future researches. We collected benthic macroinvertebrate of these ponds from the littoral zone with a pond net by kicking and sweeping. Ten-second samples were collected in each pond up to a total time of 3 to 5 minutes per pond, depending on the pond size. In addition, two of the ponds, were sampled in 2004, 2006 and 2007 providing a three-year time series. The results of this study showed that Jackknife 2 was the best of the evaluated methods based on all chosen criteria and also performed well across all studied ponds. Jackknife 1, Chao 1 and Chao 2 also presented good results and they were inferior to Jackknife 2 mainly because of the requirement for larger sub-sample sizes.