Carlos Fernandez-Delgado

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• Catedrático de Universidad
• Catedrático de Universidad at University of Córdoba

The Iberian Peninsula, in southwestern Europe, is home to a distinctive freshwater fish fauna, predominantly composed of endemic species. This is a consequence of the prolonged isolation from western Europe caused by the Pyrenees, the diverse geological and climatic gradients, and the isolation of river basins. Freshwater and diadromous fishes have...

Simple Summary: Introduced into the Ebro Basin in Spain in 1974, the invasive European catfish is now present in almost all Spanish river basins. This includes the Guadalquivir River, where it threatens native species and the ecological biodiversity of the Doñana National Park. This study provides valuable information on its current distribution us...

Most European rewilding initiatives are based on the recovery of large herbivores, particularly European bison Bison bonasus, aiming at restoring ecosystem processes and increase trophic complexity. The growing support for the release of bison as a wild species, and change its legal status, in Spain, as an ecological analogue of the extinct steppe...

Most European rewilding initiatives are based on the recovery of large herbivores, particularly European bison Bison bonasus, aiming at restoring ecosystem processes and increase trophic complexity. The growing support for the release of bison as a wild species, and change its legal status, in Spain, as an ecological analogue of the extinct steppe...

The ready availability of abundant food sources can be a key factor in the success of biological invasions. This study provides information about feeding habits, dietary niche, and seasonal and ontogenetic diet changes of the American invasive weakfish Cynoscion regalis in the Gulf of Cádiz, where its population is increasing exponentially since 20...

Aquatic ecosystems are particularly vulnerable to the introduction of non-indigenous species (NIS), leading to multi-faceted ecological, economic and health impacts worldwide. The Iberian Peninsula comprises an exceptionally biodiverse Mediterranean region with a high number of threatened and endemic aquatic species, most of them strongly impacted...

The authors regret that the printed version of the above article contained an incomplete version of Table 1, in which only 20 invasive alien species were published out of the top-ranked 24 that should have been. The correct Table 1 is shown below. The authors apologise for any inconvenience caused.

As the number of introduced species keeps increasing unabatedly, identifying and prioritising current and potential Invasive Alien Species (IAS) has become essential to manage them. Horizon Scanning (HS), defined as an exploration of potential threats, is considered a fundamental component of IAS management. By combining scientific knowledge on tax...

The bleak Alburnus alburnus is a medium body-size leuciscid fish that is naturally distributed across central European and western Asian fresh waters. However, during the last two decades A. alburnus has been widely introduced elsewhere in Europe and in northern Africa, mostly as a forage species for game fishes. Given its relatively recent history...

An important goal of LIFE INVASAQUA is to develop tools that will improve management and increase the efficiency of the Early Warning and Rapid Response (EWRR) framework for Invasive Alien Species (IAS) in the Iberian Peninsula. Horizon scanning for high risk IAS is basic when implementing measures to reduce new invasions and to focus efforts on th...

Weakfish (Cynoscion regalis) has been present in Iberian waters since at least 2011, when it was first recorded in the Guadalquivir estuary. Little is known about the preferences and feeding strategies of weakfish outside of its native range; therefore, in this work, we carried out a comprehensive study between March 2021 and September 2021 to eluc...

The Joint EIFAAC/ICES/GFCM Working group on eels (WGEEL) met by correspondence and video conference from September 7 – 10 September and 27 September – 4 October in 2021 to assess the state of the European eel and its fisheries, investigate the effects of contaminants on the reproductive capacity of the eel stock, discuss the findings of WKFEA, furt...

Since its first record in Europe as an exotic species back in 2009 at the Schelde estuary (Belgium), the weakfish Cynoscion regalis -native from North America East coast- has increased its presence in the Iberian Peninsula waters. Identified for the first time in the Guadalquivir River estuary (2011) and later in the Sado estuary (2014), C. regalis...

Se presenta una lista actualizada de las especies exóticas que se encuentran en etapa de establecimiento o de propagación de la invasión en aguas continentales de la península ibérica. La lista está basada en la evaluación sistemática de los datos en colaboración con un amplio equipo de expertos de España y Portugal. Esta lista de actualización es...

An updated list is presented of the alien species in the establishment or spread invasion stage in in-land waters at the Iberian Peninsula. The list is based on a systematic assessment of information in collaboration with a wide expert team from Spain and Portugal. This updated list is an important tool supporting the implementation of the IAS Regu...

An updated list is presented of the alien species in the transport or introduction invasion stage in inland waters of the Iberian Peninsula. The list is based on a systematic assessment of information in collaboration with a wide expert team from Spain and Portugal. This list is an important tool to support the implementation of the IAS Regulation,...

The SUDOANG project aims at providing common tools to managers to support eel conservation in the SUDOE area (Spain, France and Portugal). VISUANG is the SUDOANG Interactive Web Application that will host all these tools. The application consists of an eel distribution atlas (GT1), assessments of mortalities caused by turbines and an atlas showing...

Mistrust between scientists and non-scientist stakeholders is a key challenge in fishery management. The support of management with complex models is difficult, as these models cannot easily communicate their results to end users, resulting in a lack of confidence. As an example, the complex life cycle of the European eel raises problems of coordin...

Mistrust between scientists and non-scientist stakeholders is a key challenge in fishery management. This problem is exacerbated with the use of complex models to support management: these models suffer from difficulties in communicating their results and a lack of confidence from end users. The European eel is an illustrative example; its complex...

This guide is available at: http://www.lifeinvasaqua.com/main-files/uploads/2020/11/LIBRO-ESPECIES-INVASORAS-INGLES-FINAL.pdf

The bleak Alburnus alburnus is native to most of Europe. This cyprinid fish is a successful invader in the Iberian Peninsula. No studies exist on its foraging strategies on a large scale for this ecoregion. The aim of the present study was to compare dietary traits of invasive bleak among the main Iberian rivers and a ‘reference’ native bleak popul...

This field guide is available on: http://www.lifeinvasaqua.com/main-files/uploads/2020/07/LIBRO-ESPECIES-INVASORAS-ESPA%C3%91OL-WEB-1.pdf

This field guide is available on: http://www.lifeinvasaqua.com/main-files/uploads/2020/07/LIBRO-ESPECIES-INVASORAS-ESPA%C3%91OL-WEB-1.pdf

Freshwater ecosystems constitute only a small fraction of the planet's water resources, yet support much of its diversity, with freshwater fish accounting for more species than birds, mammals, amphibians or reptiles. Fresh waters are, however, particularly vulnerable to anthropogenic impacts, including habitat loss, climate and land use change, pol...

Freshwater ecosystems constitute only a small fraction of the planet's water resources, yet support much of its diversity, with freshwater fish accounting for more species than birds, mammals, amphibians, or reptiles. Freshwaters are, however, particularly vulnerable to anthropogenic impacts, including habitat loss, climate and land use change, nut...

Recruitment of many marine organisms depends on transport and survival of eggs and larvae from spawning grounds to nursery areas. Estuaries and neighbouring coastal waters play an important role in the recruitment of some small pelagic fish (SPF) as nursery areas. Damming of estuaries results in major alterations of their natural hydrological regim...

The native European freshwater cyprinid fish, common bleak Alburnus alburnus (Linnaeus, 1758), is an invasive non-native fish in the Iberian Peninsula, where it threatens the valuable endemic fish fauna. Despite the bleak’s invasive status, there is a dearth of studies on the biological traits of non-native populations in Europe’s Mediterranean reg...

The Doñana Natural Space (National and Natural Park) has three dominant ecosystems: dunes, beaches, and marshes. Its geographical position gives rise to a rich biota at a major stopover point in birds’ migration routes and at a very important site for wintering waterfowl. Because of this, Doñana has acquired the highest protected area categories th...

Invasive alien species (IAS) has a very significant impact on aquatic environments. In Spain these ecosystems are home to a large number of IAS and to a high diversity and endemism of fauna, especially inland fish. The threat posed by IAS and the difficulty of working in rivers and streams requires the use of different tools for their control and p...

Estuarine coastal areas play an important role in the recruitment of some small pelagic fish populations mainly when stable salinity-gradients are present. Damming of these ecosystems results in major alterations in this natural hydrological regime. Therefore, changes in the marine/freshwater balance can result in services loss, like the nursery ha...

Erosion and sediment yield are a significant problem in the Guadalquivir River basin. Such phenomena are largely driven by a land use devoted to intensive cultivation of olive trees, with a large socioeconomic influence in Andalusia. This sediment overload in rivers causes serious impacts on all fluvial ecosystem components. In this study we assess...

Over a thirty year period from 1977 to 2007, 16 Odonata species were recorded in the Nature Reserve "Laguna de Zonar", Cordova, Andalusia, Spain. Thermophilic dragonflies with wide distribution in the African continent were dominant in recent years. In 1985, Common carp Cyprinus carpio L., 1758 were introduced in an uncontrolled and illegal action,...

Anthropogenic pressures on coastal and estuarine wetlands are causing a decline in their ecological value and resources. The construction of hydraulic infrastructures stopping tidal influxes is among the most important historical and current threats to coastal wetlands. Yet, the potential effects of tidal restriction have been poorly studied in Eur...

The influence of environmental variables on native and exotic fish species richness and diversity was analysed 8 years after one of the most environmentally harmful toxic spills worldwide. Environment-diversity relationships were addressed on different scales, and values were also compared with those of six similar basins not affected by the spill,...

The European eel (Anguilla anguilla) stock has decreased by 1% from the overall population size in 1980. Consequently, Eel Managements Plans (EMPs) have been carried out across Europe in order to increase the population to a 40% minimum of the considered original. In Spain, each autonomous region has set different measures. This study shows the fir...

Following the recommendations of the Water Framework Directive (WFD) in the European Union, research on the current fish community status from the Guadalquivir River basin was addressed. Among the large quantity of information registered, this study was focused on the environmental variables that mainly influenced the presence of native or exotic s...

Doñana National Park is considered as paradigm of the conservation of the biodiversity in Spain. However, some vertebrate groups remain poorly studied, and concretely the knowledge on the fish assemblage is scarce. In this study, the composition and structure of fish assemblage in the typical temporal pond ecosystems from the marshland were studied...

In the context of the European Eel Recovery Plan, managers need confident biological information based on its own geographical areas. In the specific case of Andalusia (Southern Spain), we are developing a capture-recapture experiment based in the use of PIT-tags in order to obtain information that we lack for the species in the study area. In this...

Body size is considered to be a key functional trait determining species relationships. We analyse mean size, size diversity, and species diversity of the nektonic fish assemblage of estuarine and marine dominant species in the Guadalquivir estuary (SW Spain) on monthly samples between 1997 and 2013, identifying environmental forcing. Size diversit...

The Guadiamar River (SW Iberian Peninsula) received a major toxic spill (6 hm3) from a tailing pond in 1998 that defaunated 67 km of the main stem. Following early mud removal works, the fish assemblage was annually monitored at four affected sampling sites and one located in the upstream non-affected reach of the Guadiamar River as reference. Fish...

A long term ecological research program is developed monthly at the Guadalquivir since 1997 to date in order to assess the nekton (fish, decapod crustaceans) response to freshwater inputs (dam discharges) in a temperate estuary with regulated riverine inflow. River discharges are regulated mainly for economic purposes. Such water management usually...

On 25 April 1998, the tailing pond of the Los Frailes mine in Aznalcollar (Seville, Spain) ruptured, causing one of the most harmful environmental disasters in Europe in recent decades. Through the crack, 6 hm(3) of acidic water and metallic mud were spilt, defaunating a large area of the Guadiamar River. After the spill cleanup and habitat restora...

Erosion and sediment yield are a significant problem in the Guadalquivir River basin. It is largely driven by a land use devoted to intensive cultivation of olive trees, with a large socioeconomic influence in Andalucía. This sediment overload in rivers causes serious impacts on all fluvial ecosystem components. Fish communities are especially affe...

A long term ecological research program (LTER) is developed monthly at the Guadalquivir estuary since 1997. Inter- and intra-specific euryhalinity differences both in prey and predators seem to determine spatial species distribution at this important nursery area: the less euryhaline species (marine recruits) tends to occur at physiologically more...

The analysis of species-environment relationship has always been a central issue in ecology. Presence and absence data allow us to estimate the probability of occurrence of the species and the optimum and tolerance range (the realized niche) for the environmental variable of interest. Under a scenario of water scarcity, freshwater discharges (FSW)...

In the Mediterranean-climate zone, the recurrent drought events and the increasing water demand are usually leading to a decreased freshwater input to estuaries that threat their proper function as nursery areas. In this study, all the published results of the Guadalquivir estuary related to this topic were analysed to provide integrated and valuab...

The first record of the European catfish Silurus glanis Linnaeus, 1758 in the Guadalquivir River basin This paper describes the first record of the European catfish Silurus glanis Linnaeus, 1758, introduced into the Guadalquivir River basin. One individual of the species was captured in the Iznájar Reservoir (Córdoba, Spain) in July 2011. Most like...

Length–weight relationships were determined for 13 species captured in the marshlands of the Doñana National Park (SW Iberian Peninsula). This is the first record of length–weight relationships for two of these species.

The aim of this 12-year study was to assess the nekton (fish, decapod crustaceans) response to freshwater inputs (rainfall, dam discharges) in a temperate estuary with regulated riverine inflow. Although interannual variability in river discharges to the Guadalquivir estuary has been extremely high since the construction of a dam in 1930, a signifi...

The main oceanic and local environmental traits forcing the glass eel Anguilla anguilla (L., 1758) recruitment to the southernmost European estuary, the Guadalquivir (SW Spain), were studied during nine successive migration seasons (June 1997–December 2006) using a fishery-independent experimental survey at three sampling sites in the estuary. A cl...

This study analyzes the somatic condition of southern Iberian barbel Luciobarbus sclateri (Günther, 1868) in the Guadiamar River (SW Iberian Peninsula). This river was seriously affected by a toxic spill of about 4 million cubic meters of acidic water and 2 million cubic meters of mud rich in heavy metals. Once the spill removal works concluded, si...

The present study features the first findings on the biological traits of Atherina boyeri Risso, 1810 in the Mar Menor coastal lagoon (37º 38' N, 0º 42' W). A total of 4241 specimens were studied using samples taken from commercial catches obtained between November 1997 and September 1998. The maximum lengths were 94 mm fork length (LF) in females...

Estuaries are used as nursery grounds by numerous marine species despite being usually subject to strong anthropogenic disturbances. Abundances of marine recruits (fish and crustacean decapods) and their main prey (mysids) were monitored by monthly sampling, from June 1997 to February 2009, in the lower reaches of the Guadalquivir estuary (SW Spain...

The jarabugo Anaecypris hispanica, considered endemic to the Guadiana River basin, has been found in the Guadalquivir River. First genetic data showed a high degree of similarity to those of the Guadiana River populations. The genetic study recovered five different groups of haplotypes, the Guadalquivir River specimens belong to the largest and mos...

For the last few decades, Aphanius iberus, an endemic cyprinodontid from the Iberian Peninsula and included in international red lists, has been declining despite several management efforts. In this study we present the biology of the species in an isolated wetland managed for salt exploitation (its most common habitat type in the southeastern Iber...

Within the Guadalquivir estuary, young recruits of marine species seem to respond to changes in freshwater flow by moving with the mass of estuarine water that is most "suitable" for them. The control of the river flow, from a dam 110 km upstream from the river mouth, has an immediate effect on the estuarine salinity gradient, displacing it either...

Since its first record in a tributary of the Ebro basin in 1992, the bleak Alburnus alburnus has spread to almost the whole Iberian Peninsula. In this paper (based on electrofishing surveys in 598 localities), we provide information on the expansion of the bleak. We detail current distribution in the Ebro basin and the rivers of the Eastern Pyrenee...

The spatio-temporal distribution of the anchovy Engraulis encrasicolus in its early life stages was related to environmental conditions within the Guadalquivir River estuary (south-west, Spain) by monthly field surveys during nine periods of recruitment (May 1997 to December 2005). Anchovy post-larvae showed a consistent seasonal pattern of abundan...

The age structure, growth and reproduction of Barbus sclateri in a non-regulated section of the Segura River were similar to previously studied populations of undisturbed areas. Differences in the duration of the growth period or the reproductive cycle are considered evidence of the plasticity of the species as it adapts to different latitudes and...

Since its first record in a tributary of the Ebro basin in 1992, the bleak Alburnus alburnus has spread to almost the whole Iberian Peninsula. In this paper (based on elec-trofishing surveys in 598 localities), we provide information on the expansion of the bleak. We detail current distribution in the Ebro basin and the rivers of the Eastern Pyrene...

Catastrophic collapse of a mine tailings dam released several million cubic meters of toxic mud and acidic water into the Guadiamar River valley, southern Spain, in 1998. Remediation efforts removed most of the sludge from the floodplain, but contamination persists. Clean-up activities also produced clouds of aerosolized materials that further cont...

The age, growth and reproduction of Leuciscus pyrenaicus (Günther, 1868), an endemic cyprinid from the Iberian Peninsula, was studied from November 1987 to September 1989 in a small seasonal tributary of the Guadalquivir river basin. Maximum fork lengths observed were a 160 mm male with six scale annuli and a 171 mm female aged 7 +. Maximum ages ob...

Various studies on the ichthyofauna of many estuaries and coastal lagoons in Europe and the Mediterranean areas emphasize that these systems act as important nursery areas for marine fish, thereby supporting important fisheries (Elliott and Hemingway, 2002). The high productivity of these areas enable young-of-the-year fish (Y-O-Y; fish produced fr...

1. The age, growth and reproduction of the small, introduced fish Gambusia affinis (Baird & Girard, 1853) were studied in the estuary of the Guadalquivir river. 2. The life‐span was very short, the stock contained only two age groups: with annulus (1+ group; 10–12 months old) and without annulus (0+ group). 3. In both sexes growth restarted in Apri...

1. Age, growth and reproduction in an Atlantic population of the small fish, Aphanius iberus (Cuv. & Val., 1846), from the estuary of the Guadalquivir river were studied. 2. The growth period was from April to September and the annulus on the scales was formed in April. 3. The life-span was short with a winter age-structure of 95.9% 0+ fish, 3.9% 1...

This study was based on examination of 1476 barbels from a first-order stream located in the Guadalquivir River basin (38°N, 4°43′W). This stock comprised nine age groups of male and 11 of females. No growth was recorded between October and March, most occurring in April–June and, to a lesser extent, in July–September. A classification analysis rev...

Various studies on the ichthyofauna of many estuaries and coastal lagoons in Europe and the Mediterranean areas emphasize that these systems act as important nursery areas for marine fish, thereby supporting important fisheries (Elliott and Hemingway, 2002). The high productivity of these areas enable young-of-the-year fish (Y-O-Y; fish produced fr...

We assess how estuarine (glass eel and white shrimp) fishing activities may be affecting the recruitment of young stages of marine fish species to the Guadalquivir Estuary. We estimated the spatio-temporal abundance of fish species throughout the last 50km of the estuary during two annual cycles (May 1997–April 1999), by catching monthly samples us...

From June 1998 to May 1999, the water temperature, salinity and turbidity, together with the macrofaunal (nekton and hyperbenthos) abundance, biomass and number of species, were estimated in the Guadalquivir Estuary at five sampling stations (at 50, 40, 30, 20 and 8 km from the river mouth). Samples were taken from an anchored boat by using nets pr...

La temperatura, salinidad y turbidez del agua en el estuario del Guadalquivir, así como la abundancia, biomasa y número de especies de su macrofauna acuática (necton e hiperbentos), se estimaron mensualmente, entre junio de 1997 y mayo de 1999, en cinco estaciones de muestreo a 8, 20, 30, 40 y 50 km de la desembocadura utilizando para la toma de mu...

The age, growth and reproduction of Chondrostoma polylepis willkommi, an endemic cyprinid from the Iberian Peninsula, was studied for 2 years in a seasonal stream in the Guadalquivir River basin. Annual growth was low. Maximum ages observed were 5+ in males and 7+ in females. There was no significant difference in growth between sexes. Seasonal gro...

Possible effects of the Aznalcóllar mine accident on the fish community of the Guadalquivir Estuary were examined comparing data from one year before the accident with data from the three following years. After inter-monthly differences in water temperature and salinity had been accounted for, results did not show significant (one-way ANCOVA test,...

The age and growth of sand smelt, Atherina boyeri (Risso 1810), in the Mar Menor (SE Iberian Peninsula) were studied in samples taken from catches of local fishermen obtained between November 1997 and September 1998. The maximum lengths were 94 mm (FL, fork length) in females and 87 mm (FL) in males. Age determination based on scale readings and va...

Possible effects of the toxic waste spill, from the Aznalcóllar mine, on the fish community of the Guadalquivir Estuary were analysed by comparing its structure during the year befare the accident and duríng the three following years. Results of unívariate techníques índícated that, after effects of water temperature and salinity had been accounted...

To assess how estuarine (glass-eel and white shrimp) fishing activities may be affecting the recruitrnent of youug stagesof marine fish species to the Guadalquivir Estuary, during two annual cycles (May 1997 to April 1999), the spatio-temporal abuudance of these species throughout the last 50 km of the estuary was estirnated (monthly samples with 1...

The aquatic macrofauna of the Guadalquivir estuary were sampled (1 mm mesh persiana net) at 5 sampling sites located along the entire (except the tidal freshwater region) estuarine gradient of salinity (outer 50 km). A total of 134 fish and macroinvertebrate species was collected but only 62 were considered common or regularly present in the estuar...

In the Iberian endemic loach Cobitis paludica, in a small seasonal tributary of the Guadalquivir River, 65–70% of the total growth in length occurred in the first year of life. The maximum ages observed were 3+ years in males and 4+ years in females. Both sexes matured at the beginning of their second year of life. There was a significant differenc...