Carolina Solà

Effect of dumping and cleaning activities on the aquatic ecosystems of the Guadiamar River following a toxic flood

The main aim of the study was to document the recovery of the aquatic ecosystem after the release of toxic mining waste in the Guadiamar River Basin (Sevilla, SW Spain) in April 1998. Samples of water, plankton, periphyton and macroinvertebrates were taken once a month at nine sampling stations (six affected by the toxic release and three for control). Water hardness and pH recovered in a few weeks and did not change significantly thereafter in the river or in the marsh stations. Only the Agrio River (the tributary that received the initial waste dump) had a low pH (3-5) throughout the study period. High ammonia contents (up to 300 microM) were measured at two sampling stations due to sewage and oil mill pollution. Eutrophication was also common at most of the stations, including one reference site. The planktonic community did not differ substantially between reference and affected stations. On all occasions the small phytoplankton and zooplankton (rotifers) were dominant. Compared with the reference station, chlorophyll a in the riverine area increased, especially in the sewage-affected stations, while in the marsh area, no significant differences were found between affected and reference stations. After 6 months of cleaning operations, in November 1998 the macroinvertebrate community of the river was composed mainly of species of short life cycles typical of ponds (Heteroptera, Coleoptera and Odonata), while typical riverine species found at the upstream control station had not recolonized the river due to the transformation of the river into a series of artificial ponds constructed as sediment traps. An analysis of variance showed significantly higher values (P < 0.05) for all heavy metals analysed (Zn, Cu, Pb, As, Cd, Sb, Tl) in plankton and macroinvertebrate communities from impacted sites. Values found in invertebrates were highly variable, with a mean concentration of the most abundant metals, Zn and Cu, between two and three times those found in unpolluted areas. Values for As were up to five times higher while Pb, Sb and Tl showed up to 10-fold increases. At the affected stations, the metal concentrations found in biofilms, plankton and particulate material were more than five times greater than those in invertebrates. The slow recovery of the aquatic ecosystem clearly reflected the impact of the metal discharge and the subsequent cleaning activities following the mine spill, as well as the sewage inputs at two of the stations studied.

Human Pressure and Its Effects on Water Quality and Biota in the Llobregat River

The Llobregat River has severely been impacted by anthropogenic pressures since long time ago. The mid and lower Llobregat basin holds an important concentration of industries, agricultural activities, and urban areas, with high associated water demand and wastewater discharge. Salt mine activities, hydropower water diversion, and flow regime alteration by dams affect both the Llobregat headwaters and middle reaches. These impacts have historically caused the degradation of riparian biological communities and the loss of habitats along the river. The high amount of information available on water quality and biological community composition allows establishing a suitable monitoring program aimed to improve its ecological status. Some measures have been applied to mitigate the impacts, and Llobregat’s biological quality status has progressively improved. The biological communities, mainly diatoms and macroinvertebrates, have recovered even those inhabiting the river mouth, but mostly during wet periods. However, some anthropogenic pressures still remain and Llobregat’s biological status is not completely restored. The high amount of small weirs and hydropower water diversion along the Llobregat and Cardener Rivers, together with flow regime regulation by dams, riparian degradation, and point nutrient discharges (from water sewage plants) and salt debris due to mine activities, result in a poor biological quality status in the mid and lower Llobregat River. Fish fauna is the most altered community, with a high number of nonnative species present. The occurrence of some priority substances and emergent pollutants (e.g., endocrine disruptors, heavy metals, pesticides, flame retardants, drugs, and pharmaceuticals), even at low concentrations, further alter the biological quality. The changes in the biological community structure in the middle part of the river can be detected by using biomarkers, and these should additionally be considered as biological monitoring tools necessary for an integral ecological status diagnosis.

Comparing Chemical and Ecological Status in Catalan Rivers: Analysis of River Quality Status Following the Water Framework Directive

In Europe, diverse biological indices and metrics have been developed for ecological status assessment in rivers using macroinvertebrate, diatoms, macrophytes, and fish communities according to the Water Framework Directive (2000/60/EC). Additionally, priority and hazardous substances (pesticides, PAHs, heavy metals, chlorinated and non-chlorinated solvents, endocrine disruptors, etc.) must be analyzed using their environmental quality standards (EQS) according to the 2008/105/EC Directive. Chemical and biological elements have to be properly combined to set the final water quality status. We compare ecological and chemical status outputs in a Mediterranean watershed (the Catalan river basins, NE Spain), in order to provide useful information about the strengths and weaknesses of quality status classification in rivers.

TREHS: An open-access software tool for investigating and evaluating temporary river regimes as a first step for their ecological status assessment

When the regime of a river is not perennial, there are four main difficulties with the use of hydrographs for assessing hydrological alteration: i) the main hydrological features relevant for biological communities are not quantitative (discharges) but qualitative (phases such as flowing water, stagnant pools or lack of surface water), ii) stream flow records do not inform on the temporal occurrence of stagnant pools, iii) as most of the temporary streams are ungauged, their regime has to be evaluated by alternative methods such as remote sensing or citizen science, and iv) the biological quality assessment of the ecological status of a temporary stream must follow a sampling schedule and references adapted to the flow- pool-dry regime. To overcome these challenges within an operational approach, the freely available software tool TREHS has been developed within the EU LIFE TRIVERS project. This software permits the input of information from flow simulations obtained with any rainfall-runoff model (to set an unimpacted reference stream regime) and compares this with the information obtained from flow gauging records (if available) and interviews with local people, as well as instantaneous observations by individuals and interpretation of ground-level or aerial photographs. Up to six metrics defining the permanence of water flow, the presence of stagnant pools and their temporal patterns of occurrence are used to determine natural and observed river regimes and to assess the degree of hydrological alteration. A new regime classification specifically designed for temporary rivers was developed using the metrics that measure the relative permanence of the three main phases: flow, disconnected pools and dry stream bed. Finally, the software characterizes the differences between the natural and actual regimes, diagnoses the hydrological status (degree of hydrological alteration), assesses the significance and robustness of the diagnosis and recommends the best periods for biological quality samplings.

Fish as Ecological Indicators in Mediterranean Streams: The Catalan Experience

The Water Framework Directive includes fish fauna as one of the biological elements, jointly with aquatic flora and benthic invertebrates, to assess and monitor water and habitat quality. Successful implementation of the Directive depends in part on the development of reliable, science-based tools to directly assess biological conditions. Although fish have been used as ecological indicators for more than 30 years around the world, mainly in North America and more recently in Europe, few studies have been done in Mediterranean streams. Fish assemblages of the Mediterranean basin, similarly to other Mediterranean areas such as California, have particular characteristics that hamper IBI’s development: few native species, poor knowledge of their ecological requirements, high number of endemisms with a wide range of tolerance to environmental variations and many exotic species. This chapter summarizes our experience in developing fish-based tools in Catalonia. We discuss the challenges and difficulties to develop these approaches in Mediterranean streams. We show the IBICAT2010 as a fish-based assessment method suitable for the evaluation of the ecological status of Catalan rivers. Moreover, we assess size-related variables as a bioassessment tool because population size structure can provide insights into species-specific applications and management. Finally, we analyse the longitudinal connectivity throughout Catalan rivers and fish passes by using the index of river connectivity (ICF) specially designed to Catalan rivers.

Biological Indices Based on Macrophytes: An Overview of Methods Used in Catalonia and the USA to Determine the Status of Rivers and Wetlands

Aquatic macrophytes are commonly used as the basis for assessing the ecological condition of wetlands and rivers and are considered the basis for some of the best indicators of these ecosystems within their landscape. We review key approaches that utilize plant traits as the basis for water resource assessment, including the floristic quality assessment index (FQAI), the Qualitat del Bosc de Ribera (riparian forest quality index or QBR), indicator species analysis (IndVal), and multimetric indexes of ecological integrity (MMIs). The FQAI quantifies how “conservative” a plant species is by evaluating the degree to which it is adapted to a specific set of environmental conditions and then uses that information to assess plant community response by examining the aggregate degree of “conservatism” for all species in a community. The index codifies expert opinion a priori on the ecological nature and tolerance of macrophyte species and has been shown to be sensitive to human activities. Plant traits can also form the basis for assessment using indicator species analysis (IndVal), which allows the environmental preferences of target species to be identified and related to habitat type, site characteristics, environmental change, or gradients of human disturbance. We applied this technique to identify indicator species for river ecosystems in Catalonia. Finally, assessment approaches based on multiple plant-based metrics are illustrated. Species traits used in multimetric indexes (MMIs) are based on testable hypotheses about how plant communities change along human disturbance gradients. These approaches and their application to Catalan and US wetlands and rivers are explored.

A First Biopollution Index Approach and Its Relationship on Biological Quality in Catalan Rivers

The purpose of this chapter is to present results of the applicability of the most well-known biopollution (BP) and biocontamination (BC) indices available in the literature by using information from the standard monitoring programme for fish carried out in Catalonia. As a part of this exercise, the pertinence of the results is evaluated by answering two questions: (1) are the BP&BC indices actually indicators for quality status, i.e. do their results respond to indicators of pressures on water bodies? And if so, (2) are the indices redundant with the existing indices of quality status for a given biological element? This discussion will be done in relation to the use of information on alien species (AS) for the purpose of future management and the ensuing role of uncertainty in the ecological assessment on water bodies according to the Water Framework Directive (2000/60/EC).

Hydromorphological Methodologies to Assess Ecological Status in Mediterranean Rivers: Applied Approach to the Catalan River Basin District

Methodologies currently used to assess hydromorphological features in Mediterranean rivers are reviewed in this chapter. Most relevant methodologies developed across Europe in compliance with WFD (Water Framework Directive) are also analyzed, along with their adaptations to different spatial scales from European, national to regional scales. We also present those hydromorphological protocols that have been developed, used and tested in the Catalan River Basin District, within the framework of monitoring programmes under the requirements of the WFD. The Catalan Water Agency developed a comprehensive protocol to assess hydromorphological conditions in Catalan watersheds, named HIDRI, which assesses and combines hydrological alteration, river continuity and morphological conditions. HIDRI is a compiled protocol based on different metrics and includes large information at river catchment scale.