Fishway design for large vs small dams in the Sierra Norte of Sevilla Natural Park

En este trabajo se realiza un análisis pormenorizado de la adecuación de una escala para peces que les permita salvar el obstáculo de la presa de Los Melonares (río Viar, Sevilla). Se realiza un análisis desde una doble vertiente: la capacidad fisiológica de los peces de la cuenca del Viar y de las propiedades hidráulicas de un diseño que en su día fue desestimado. Finalmente se comenta la situación de la escala del azud de Gargantafría que si se considera viable para el paso de ciprínidos ibéricos.________________________In this work a detailed analysis of the utility of a fishway for the stream fish to pass the large damm of Los Melonares is made. This analysis is done from the physiological capacity of the fi shes point of view and from the hydraulic properties of a fi shway design, fi nally rejected. The situation of an alternative project, the Gargantafria fi shway, is fi nally commented

Freshwater Fish Biodiversity in a Large Mediterranean Basin (Guadalquivir River, S Spain): Patterns, Threats, Status and Conservation

The Guadalquivir River Basin is one of the largest in the Iberian Peninsula and has a remarkable freshwater biodiversity. Although many studies on hydrological regimes or water quality have been conducted in this basin the biodiversity of freshwater fish, as well as their distribution and conservation status, has never been globally addressed as in other Iberian basins. In this context, we synthesized information on freshwater fish using field procedures and a bibliographic search. Fish distribution patterns at different spatial scales and general environmental conditions were analyzed as well as the conservation status of the fish community. We documented the presence of 40 species (20 native and 20 exotic) in the basin during the 20th century until today. However, we only captured 18 species during the field sampling, with a prevalence for any native species of less than 23% (except Luciobarbus sclateri). The highest species richness was found in mid reaches, while the lower reaches had very low diversity values. Around 50% of species are threatened; according to the IUCN, several species are declining at an alarming rate and others are probably extinct and/or their current status is unknown. Human disturbances during the last few decades have caused serious changes in fish distribution and consequently to their conservation status. Hydrological alterations, intensive agriculture and introduced species are probably the principal reasons for Guadalquivir’s ichthyofauna imperilment. Our study indicates an urgent and real need to identify important areas for fish conservation to guarantee a minimum fish biodiversity conservation over the long term, as well as effective strategies for fish recovery where it still is possibleThis research was funded by the Junta de Andalucía, Convocatoria de Proyectos de Excelencia (P07-RNM-03309), and was carried out at the Centro Internacional de Estudios y Convenciones Ecológicas y Medioambientales (CIECEM) of the University of Huelva. We wish to thank everyone from the CIECEM for their invaluable help and logistic suppor

Spatial distribution of exotic fish species in the Guadiana river basin, with two new records

This work updates the spatial distribution of the exotic fish species in the Guadiana river basin. To this effect, 241 river stretches and 37 reservoirs and lakes were sampled, corresponding to 261 UTM 10 × 10 Km squares. A total of 12 exotic species were found, including two new species that had not been previously cited in the area, the channel cat-fish (Ictalurus punctatus) and the roach (Rutilus rutilus). These two species, related to lentic systems, had a very restricted distribution in the basin, probably as a consequence of its recent introduction. The expansion of the remaining exotic species was also confirmed. Some species as the pumpkinseed sunfish (Lepomis gibbosus), the mosquitofish (Gambusia holbrooki) or the largemouth bass (Micropterus salmoides) have become common components of the fish community, not only in reservoirs but also in lotic systems.Este trabajo actualiza la distribución espacial de las especies de peces exóticas presentes en la cuenca del río Guadiana. Para ello se han muestreado 241 tramos fluviales y 37 embalses y lagos que se corresponden con 261 cuadrículas UTM 10 × 10 Km. Se encontró un total de 12 especies de peces exóticos, incluyendo dos nuevas especies no citadas hasta el momento en la cuenca: el pez gato punteado (Ictalurus punctatus) y el rutilo (Rutilus rutilus). Estas dos especies, relacionadas con medios leníticos, tuvieron un área de distribución muy restringida en la cuenca, consecuencia probable de su reciente introducción. Además se confirmó la expansión del resto de especies exóticas. Algunas de ellas como el pez sol (Lepomis gibbosus), la gambusia (Gambusia holbrooki) o el black-bass (Micropterus salmoides) se han convertido en componentes habituales de las comunidades de peces, no s'olo en embalses, sino también en medios lóticos

Los peces continentales de la provincia de Cádiz

La ictiofauna continental de la provincia de Cádiz está constituida por 18 especies, de las que 12 son autóctonas y cinco autóctonas estrictamente de agua dulce. Esto significa que más del 50% de las especies de peces estrictamente dulceacuícolas que habitan la provincia son introducidas. Ello contrasta con que de las cinco autóctonas tres son prácticamente endémicas de las cuencas gaditanas (cachuelo, colmilleja y fartet serán descritas en un futuro próximo como nuevas especies para la ciencia). Es decir, la ictiofauna gaditana posee un elevado grado de endemicidad y por tanto un valor de conservación igualmente alto. Esto contrasta con la delicada situación que atraviesan estas mismas especies. Considerados en conjunto, los cursos de agua que surcan la provincia de Cádiz poseen el mayor valor de conservación, basado en los peces, de todos los de la mitad meridional de España. De entre todos ellos destaca el Hozgarganta, que está considerado como el río mejor conservado de toda España, en cuanto al valor de su ictiofauna se refiere. La ictiofauna típica de un río gaditano estaría formada por tres especies: barbo, boga y cachuelo. Estas especies se distribuyen de manera muy desigual a lo largo del curso de los ríos y dentro de tramos específicos tienden a agruparse configurando distribuciones también heterogéneas. Las razones de esta desigual distribución no son bien conocidas, si bien al menos parcialmente, pudieran estar relacionadas con la degradación de los ríos por las actividades humanas. Entre los peces gaditanos más amenazados se encuentra el fartet. Esta especie posee unos requerimientos ecológicos muy estrictos que le obligan a ocupar ambientes muy precisos y escasos. En apariencia esta especie, que necesita de medios acuáticos permanentes, no tolera bien la presencia de otros peces por lo que está obligada a ocupar ambientes extremos donde no puede sobrevivir ninguna otra especie. La conservación de los fartets ha de hacerse a la luz de esta circunstancia. La ictiofauna que habitó en la antigua laguna de La Janda es hoy casi un enigma. Sin embargo, estudios recientes han puesto de manifiesto que en el bajo Barbate aún existe una comunidad diversa y muy productiva que apunta a que en La Janda podría haber existido una comunidad más rica aún y al menos igualmente productiva. También los pequeños cursos de agua del entorno de Tarifa poseen una ictiofauna peculiar, si bien muy amenazada por la fragilidad de estos pequeños ecosistemas

A timeline for the urbanization of wild birds: The case of the lesser kestrel

The Lesser kestrel (Falco naumanni) evolved as a separate species in the Old-World kestrel radiation starting in the late Miocene. Given that the first cities were erected in the Holocene, this urban colonial raptor has only become a major town dweller recently in its evolutionary history. Today, more than 95% of lesser kestrel colonies in Spain and other Mediterranean countries are on buildings, and the remaining few are on rocky outcrops, that may have been the original nesting substrate for this cavity-nesting bird. Lesser kestrel fossils are well represented in cave sites, and their paleontological distribution, spanning from the Early Paleolithic to the Epipaleolithic, agrees well with its current breeding distribution. According to classical sources, such as the works of Columella and Pliny the Elder, and the presence of a skeletal remain in a Roman villa near Madrid, lesser kestrels may have nested in buildings and in urban settings for at least 2000–2500 years. However, there are no surviving colonies in structures older than 1400 years in Andalusia, nor in Spain. For a sample of 349 colonies on ancient buildings, a majority of the structures had been erected between the 15th and 17th centuries, this putting a time limit of about 300-600 years to the existence of those seemingly immemorial colonies. For specific towns and buildings, written references for the presence of lesser kestrel colonies do not go back more than two centuries. In fact, the Cathedral of Sevilla may be the structure with the longest continuous occupation by lesser kestrels recorded up to present time, from 1834 to 2020. Lesser kestrels were possibly too common in human settlements in the past as to be noted as special. This may explain the scarcity of references to the species until the 19th century. In any case, the same lack of information affects the other major Eurasian urban birds, as no timeline exist for the urbanization process of any other bird species. We propose that lesser kestrels became urban breeders when both adequate cavities in buildings and cereal fields, where they capture their invertebrate prey, became available in their breeding range, several millennia ago. However, urban colonies, in contrast with the ones on stable geological substrates, have been forced to move from building to building when older ones became ruinous or were rebuilt, but new structures with suitable cavities became available throughout History