Ecological impact of recreational bathing at Las Presillas (Lozoya River, Sierra de Guadarrama National Park, central Spain)

The ecological impacts of recreational uses on the rivers of Sierra de Guadarrama National Park (SGNP) have been scarcely studied. To assess the impacts of these uses at Las Presillas (an area with small dam along a section of the Lozoya River), and in the Lozoya River (upstream and downstream of the dams), the dynamics of the organic seston (FPOM), physicochemical vari-ables (electric conductivity, dissolved oxygen, Temperature, and pH) and biological variables (fecal coliforms, fecal streptococci, and aquatic macroinvertebrates) during the recreational (July to September) and nonrecreational (October) periods were assessed. The variations observed in the physicochemical parameters were associated with autumnal influence. However, at Las Presillas, different values were found than at the rest of the surveyed sites, characterized by an increase in the concentration of FPOM and, human fecal contamination (although they did not reach dangerous levels) and the response of the macroinvertebrate communities, which resulted in a clear decrease in the IBMWP index and other quality metrics, during the recreational period. These findings suggest that the combined effects of the dams and recreational activities at Las Presillas generate functional dynamics in that alter the habitat in summer. The identification and study of these impacts through the application of innovative indices and quality classes that integrate and contextualize Las Presillas in the SGNP monitoring network, have been identified as key management and conservation tool

Seeking for the best conditions for fish fossil preservation in Las Hoyas Konservat-Lagerstätte using microbial mats

Actuotaphonomic experiments demonstrate how microbial mats prevent or delay destructive processes. The rate at which carcasses are covered is a key to their preservation. Because of the growth rate of microbial mats depends on environmental conditions, a set of experiments have been carried out emulating the Barremian environmental conditions, analysed for temperatures at 14°C and 26°C (cooler and warmer seasons respectively) and atmospheric pCO2 (1000 ppm). For this purpose, the microbial mats were grown in mesocosms within an environmental chamber. Variations in primary production were quantified by measuring changes in dissolved O2 concentration in the water. Zebrafish carcasses were laid on the mats, and their coverage rates were calculated from the daily surface area covered by the mat. The results showed that the fish was covered twice as fast at 26°C, in coincidence with the highest values for the gross primary production and community respiration of the microbial mats. Therefore, for these Barremian conditions, the early stages of carcasses preservation would take place most effectively during the warmer seasons as decomposing activity would release nutrients that would enhance, together with temperature, the growth of matsThis study was funded by the Spanish Ministry of Science, Innovation and Universities [project PID2019-105546GB-I00

Temporal variation of phytoplankton in two neighbouring Mediterranean shallow lakes in Doñana National Park (Spain)

This study was aimed at describing the phytoplankton dynamics and structure of two eutrophic to hypereutrophic Mediterranean shallow lakes (Santa Olalla and Dulce). The two systems are close together and can function as one water body at times of heavy rainfall, but once separated, they evolve differently. The Shannon diversity index was low for both shallow lakes (average values of 1.11 in Santa Olalla and 1.79 in Dulce). The average phytoplankton Chl a concentrations and primary production rates were very high, although slightly higher in Santa Olalla (365.2 mg m-3 and 1.29 g C m-3 h-1, respectively) than in Dulce (230 mg m-3 and 0.88 g C m-3 h-1). Phytoplankton variation in the lakes was related to shifts in the physical and chemical features of lake water as well as hydrological conditions, a finding that is corroborated by the canonical correspondence analysis results, which showed a different pattern of evolution in each system. Eight functional groups were found in Santa Olalla (D, H1, J, K, M, S1, W2 and Y), although the D, W2 and Y groups were only predominant during the first four months of the study. For the rest of the period, the system was particularly dominated by the H1, K and S1 groups. Dulce exhibited a more complex distribution of phytoplankton functional groups over time. Ten functional groups were observed in this system (D, H1, J, K, M, P, S1, S2, W2 and Y). Some characteristics of these systems, such as rapid water volume fluctuations, low light penetration and low concentration of inorganic nutrients, are stressful conditions for phytoplankton, which may account for the low phytoplankton diversity and the equilibrium phases recorded for many months in both wetlands.El presente estudio tiene como objetivo describir la dinámica y estructura del fitoplancton en dos lagunas eutróficas a hipereutróficasMediterráneas (Santa Olalla y Dulce, España). Ambos sistemas están muy próximos y se unen superficialmente en periodos de fuertes lluvias, sin embargo, cuando el nivel desciende, evolucionan de forma separada. El índice de diversidad de Shannon fue bajo para ambos sistemas (valores promedio de 1.11 en Santa Olalla y 1.79 en Dulce). La concentración media de Chl a y las tasas de producción primaria del fitoplancton fueron muy altas, aunque ligeramente superior en Santa Olalla (365.2 mg m-3 y 1.29 g C m-3 h-1, respectivamente) con respecto a Dulce (230 mg m-3 y 0.88 g C m-3 h-1). Las variaciones del fitoplancton están relacionadas con cambios en las características físicas y químicas del agua, así como con las condiciones hidrológicas, lo que es corroborado por el Análisis de Correspondencia Canónica (CCA), que muestra un patrón de evolución diferente en ambos sistemas. En Santa Olalla fueron observados ocho grupos funcionales (D, H1, J, K, M, S1, W2 y Y), si bien los grupos D, W2 y Y sólo predominaron en los primeros cuatro meses de estudio. El resto del tiempo, el sistema estuvo dominado sobre todo por los grupos H1, K y S1. Dulce mostró una distribución más compleja de grupos funcionales a lo largo del tiempo, observándose diez grupos (D, H1, J, K, M, P, S1, S2, W2 y Y). Algunas de las características de ambos sistemas, como la rápida fluctuación en el volumen de agua, la baja penetración de la luz o la escasa concentración de nutrientes inorgánicos, son condiciones de estrés para el fitoplancton, lo que puede explicar su baja diversidad y las fases de equilibrio registradas durante muchos meses en ambos humedales

A theropod trackway providing evidence of a pathological foot from the exceptional locality of Las Hoyas (upper Barremian, Serrania de Cuenca, Spain)

We describe a trackway (LH-Mg-10-16) occurring in laminated carbonated limestones of the Las Hoyas locality, Serranı´a de Cuenca, Spain. It is unmistakably a large theropod dinosaur trackway encompassing two unusual aspects, namely, wide-steps, and a set of equally deformed left footprints (with a dislocated digit). The layer also preserves other vertebrate trails (fish Undichna) and different impressions in the sediment. To address these complex settings, we devised a multidisciplinary approach, including the ichnological and taphonomical descriptions, characterisation of the rock lithofacies using thin-sections, 3D structuredlight digitalisation with a high precision of 200–400 μm, and a geometric morphometric comparison with a large sample of bipedal dinosaur trackways. Sedimentary analyses showed that the trackway was produced in a humid, benthonic microbial mat, the consistency and plasticity of which enabled the preservation of the details of the movement of the animal. The results of the geometric analysis indicate that the “wide-steps” of the trackway is not unusual compared to other trackways, providing evidence that it was made by a single individual with an estimated hip height approximately 2 m. Analogous pathologies in extant archosaurs that yield the combination of wide steps and deformed digits in the same trackway were considered. All results mutually support the hypothesis that a large theropod dinosaur, with a pathological foot, generated the trackway as it crossed an area of shallow water while slowly walking towards the main water source, thus stepping steadily over the benthonic mat over which multiple fish were swimmin

Riotinto: un universo de mundos microbianos

El río Tinto es un ambiente extremo caracterizado por un pH muy bajo y altas concentraciones de metales en disolución. Las extremas condiciones del río son en gran medida producidas y mantenidas por el componente biológico del ecosistema, principalmente por organismos procarióticos quimiolitótrofos. Las algas eucarióticas son los otros productores primarios del sistema mientras que hongos y bacterias heterotróficas juegan el papel de consumidores y descomponedores. Otros consumidores son protistas heterotróficos y, en ocasiones, rotíferos. El río en sí tiene una amplia variedad de ambientes en donde se desarrollan distintas comunidades (bentónicas en zonas aerobias, neustónicas en la superficie de aguas semiquietas, planctónicas en la columna de agua óxica y anóxica), además, las zonas adyacentes al río como los montones de mineral, las galerías mineras o el acuífero son ambientes distintos y aún inexplorados. A pesar de las condiciones extremas de este ecosistema, el río Tinto posee una gran diversidad de comunidades microbianas, cuyas interacciones son de gran interés para la ecología microbiana.The Tinto River is an extreme environment characterized by a very low pH and high concentration of heavy metals in solution. The extreme features of the river are produced and sustained by the biological components of the ecosystem, mainly by chemolithoautotrophic prokaryotic organisms. Eukaryotic algae are another primary producers in the system, while fungi and heterotrophic bacteria play the role of consumers and decomposers. Other consumers are heterotrophic protists and sometime rotifers. The river has a wide variety of environments where different communities develop (benthonic in aerobic zones and neustonic in the surface of calm waters, planktonic in the anoxic and oxic water column). In addition, adjacent zones of the river, like the piles of mineral, the mining galleries or the aquifer, are interesting and unexplored. In spite of the extreme conditions of this ecosystem, the Tinto River has a great diversity of microbial communities, whose interaction are of great interest for microbial ecology

Estudio de la comunidad microbiana de un ecosistema extremo : el Río Tinto

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 18-11-199

Archaeal amd bacterial community composition of a pristine coastal aquifer in Doñana National Park, Spain

This is an electronic version of an article published in Aquatic Microbial Ecology. López Archilla, A.I. et al. Archaeal amd bacterial community composition of a pristine coastal aquifer in Doñana National Park, Spain. Aquatic Microbial Ecology 47 (2007): 123-13

Plant Tissue Decay in Long-Term Experiments with Microbial Mats

The sequence of decay in fern pinnules was tracked using the species Davallia canariensis. Taphonomic alterations in the sediment⁻water interface (control tanks) and in subaqueous conditions with microbial mats were compared. The decay sequences were similar in control and mat tanks; in both cases, pinnules preserved the shape throughout the four-month experience. However, the quality and integrity of tissues were greater in mats. In control tanks, in which we detected anoxic and neutral acid conditions, the appearance of a fungal⁻bacterial biofilm promoted mechanical (cell breakage and tissue distortions) and geochemical changes (infrequent mineralizations) on the external and internal pinnule tissues. In mats, characterized by stable dissolved oxygen and basic pH, pinnules became progressively entombed. These settings, together with the products derived from mat metabolisms (exopolymeric substances, proteins, and rich-Ca nucleation), promoted the integrity of external and internal tissues, and favored massive and diverse mineralization processes. The experience validates that the patterns of taphonomic alterations may be applied in fossil plants