Jaume Cambra

Structure and function of benthic algal communities in an extremely acid river

The composition of algal species and pigments and the structural and functional characteristics of the algal community were investigated in an acid stream of southwestern Spain, the Río Tinto. The algal community had low diversity and showed few seasonal differences. It was mainly made up of Klebsormidium flaccidum Kütz. (Silva, Mattox & Blackwell) that produced long greenish or purplish filaments, Pinnularia acoricola Hust. (producing brown patches) and Euglena mutabilis Schmitz. The algal filaments made up a consistent biofilm that also included fungal hyphae, iron bacterial sheaths, diatoms, and mineral particles. HPLC analyses on Río Tinto samples showed that undegraded chl accounted for 67% of the total chl in the filamentous patches but were a minority in the brown patch (2.6%). The brown patch had a concentration of carotenoids eight times lower than that observed in the green patch. When chl concentrations were weighted for the proportion of the different patches on the streambed, undegraded chl a accounted for 89.2 mg chl a·m−2 of stream surface area (5.4 g C·m−2). This high algal biomass was supported by relatively high nutrient concentrations and by a high phosphatase activity (Vmax = 137.7 nmol methylumbelliferyl substrate·cm−2·h− 1 , Km = 0.0045 μM). The remarkable algal biomass in Río Tinto potentially contributed to the bacterial–fungal community and to the macroinvertebrate community and emphasizes the role that the algae may have in the organic matter cycling and energy flow in extreme systems dominated by heterotrophic microorganisms.

Diatom communities and water quality assessment in Mountain Rivers of the upper Segre basin (La Cerdanya, Oriental Pyrenees)

Epilithic diatoms of mountain rivers from the upper Segre catchment (Oriental Pyrenees) were studied in 1998, during three different seasons: March, July and September. Four rivers, the river Segre and its three most important tributaries, Duran, Molina and Querol, were sampled in upstream and downstream stretches. The diatom communities were comparable in all upstream stretches of these mountain rivers draining siliceous substrates. Dominant taxa were Achnanthidium subatomus, Diatoma mesodon, Encyonema cf. minutum, E. silesiacum, Fragilaria arcus, F. capucina, Gomphonema calcifugum, G. pumilum, Meridion circulare and Nitzschia pura. Changes in water quality in the downstream stretches lead to the appearance of pollution tolerant taxa, such as Eolimna minima, Gomphoneis minuta, Navicula gregaria, and Nitzschia inconspicua. As a result, the values obtained with the diatom water quality indices (IPS Specific Polluosensitivity Index, CEE and IBD Biological Diatom Index) decreased. The diatom community composition and the derived water quality values did not change in the upstream stretches over the year. In contrast, significant changes were observed in the downstream stretches with best water␣quality in July, during high flows due to melting snow, and worst values in September, during low␣discharge. The diatom indices, especially the IPS, showed a good performance in these mountain rivers.

Benthic diatoms in Western European streams with altitudes above 800 m: characterisation of the main assemblages and correspondence with ecoregions

High altitude rivers in European mountains show a large diversity of benthic diatom assemblages. Diatoms were studied from rivers of the Alps, the Pyrenees, the Massif-Central and the Iberic system. The study area spread across four countries, Italy, France, Switzerland and Spain. Since 2000, the European Water Framework Directive (WFD) has required the assessment of stream quality using bioindicators and any deviation from reference conditions measured. References for each river type and for each bioindicator, such as diatoms, are in the process of being defined. System A is a typological system proposed by the WFD, in which ecoregions spread over several countries were defined. The first aim of this study was to assess the importance of these ecoregions for diatoms compared to other environmental factors. To reduce the heterogeneity of the diatom assemblages due to the river continuum and also pollution, only the rivers higher than 800 meters were selected. These rivers include a majority of sites that are only slightly polluted, or not at all. In total 261 sampling sites were considered from four ecoregions: the Iberic region, the Pyrenees, the Alps and the Western Highlands. The sampling sites were characterized by differences in geology, distance from the source and altitudes. Statistical analysis showed that geographic ecoregions of system A and geology were the most important environmental descriptors for diatoms. Distance from the source and altitude were less important and pollution was the least important parameter. The second aim was to describe and to typify the main diatom assemblages of these European mountains. Eight clusters gathered into four main groups were identified. Group I was mainly recorded in the Alps and the Pyrenees; group II had in common its close proximity to the source; group III was often found in the Western Highlands on crystalline geology, and group IV was present in all ecoregions and included weakly polluted streams. Some suggestions for the improvement of the ecoregions based on benthic diatoms were given in the conclusion.

Comparability of river quality assessment using macrophytes: A multi-step procedure to overcome biogeographical differences

This paper exposes a new methodological approach to solve the problem of intercalibrating river quality national methods when a common metric is lacking and most of the countries share the same Water Framework Directive (WFD) assessment method. We provide recommendations for similar works in future concerning the assessment of ecological accuracy and highlight the importance of a good common ground to make feasible the scientific work beyond the intercalibration. The approach herein presented was applied to highly seasonal rivers of the Mediterranean Geographical Intercalibration Group for the Biological Quality Element Macrophytes. The Mediterranean Group of river macrophytes involved seven countries and two assessment methods with similar acquisition data and assessment concept: the Macrophyte Biological Index for Rivers (IBMR) for Cyprus, France, Greece, Italy, Portugal and Spain, and the River Macrophyte Index (RMI) for Slovenia. Database included 318 sites of which 78 were considered as benchmarks. The boundary harmonization was performed for common WFD-assessment methods (all countries except Slovenia) using the median of the Good/Moderate and High/Good boundaries of all countries. Then, whenever possible, the Slovenian method, RMI was computed for the entire database. The IBMR was also computed for the Slovenian sites and was regressed against RMI in order to check the relatedness of methods (R(2)=0.45; p<0.00001) and to convert RMI boundaries into the IBMR scale. The boundary bias of RMI was computed using direct comparison of classification and the median boundary values following boundary harmonization. The average absolute class differences after harmonization is 26% and the percentage of classifications differing by half of a quality class is also small (16.4%). This multi-step approach to the intercalibration was endorsed by the WFD Regulatory Committee.

Ecological impact and recovery of a Mediterranean river after receiving the effluent from a textile dyeing industry

The textile industry is one of the largest sectors globally, representing up to 20% of industrial water pollution. However, there is limited insight into how fluvial ecosystems respond and recover from this impact. From summer 2012 to spring 2013, we examined water quality and ecological status upstream and 1.5km downstream the input of a textile industry wastewater treatment plant (WWTP) in Ripoll River, NE Spain. The ecological status was determined via diversity measures and 10 biotic indices based on diatoms, macrophytes, macroinvertebrates and fish. Our results showed that the WWTP severely deteriorated water quality and biological communities at the discharge site, but that they improved at 1.5km downstream. Severity also varied across taxa and seasons, being fish the most affected taxa and spring the season with the best ecological status. The strong correlation amongst water quality variables and many biotic indices across taxa indicated that this is a chronic pollution event affecting multiple trophic levels. Thus, this study suggests that there is an urgent need to invest in wastewater treatment in this industry to preserve the ecological integrity of Ripoll River and especially its fish fauna. Likewise, it illustrates the diagnostic power of biotic indices based on diatoms, macroinvertebrates and fish, as driven by the European Water Framework Directive.

Effects of light and temperature on Chara vulgaris (Charophyceae) gyrogonite productivity and polymorphism – palaeoenvironmental implications

Abstract: To test the influence of light and temperature on intraspecific gyrogonite variation, two common European charophyte species, Chara vulgaris and Chara globularis, were studied indoors under controlled environmental conditions. A total of 60 plants of each species were incubated under different combinations of four irradiances (L1 = 30 μmol PAR m−2 s−1; L2 = 150 μmol PAR m−2 s−1; L3 = 500 μmol PAR m−2 s−1 and L4 = 1000 μmol PAR m−2 s−1) and three water temperatures (T1 = 15°C; T2 = 25°C and T3 = 35°C). These parameters simulate temporary ponds from the Mediterranean region in the summer and help in understanding charophyte reproduction in shallow temporary ponds of past geological periods. After 102 days, gyrogonite productivity was evaluated, and a morphometric analysis of the gyrogonites produced was performed. Our results indicated that both irradiance and water temperature play a key role in C. vulgaris intraspecific gyrogonite variation. Gyrogonites tended to increase their size as irradiance and temperature increased. However, in extreme conditions (L4 and T3), an opposite trend was observed, with gyrogonites becoming significantly smaller. Our results agree with the distribution patterns of fossil gyrogonite assemblages. Using the present data, we hypothesise that charophytes in historic temporary floodplain water bodies produced smaller gyrogonites in response to the stressful environments induced by high irradiances and temperatures.

Bryophyte communities of Mediterranean Europe: a first approach to model their potential distribution in highly seasonal rivers

Abstract Mediterranean watercourses are among the most threatened ecosystems worldwide, being increasingly important to understand environmental drivers of biotic assemblages. Our aim was to provide a comprehensive picture of bryophyte communities in Mediterranean rivers and to determine the environmental factors that influence their distribution. We used floristic data collected for inter-calibration purposes under the European Water Framework Directive and River Habitat Survey, from 474 river reaches in six countries of the European Mediterranean basin. We analysed data through classification, ordination and environmental niche modelling techniques, and classified taxa according to biogeographic and aquatic habitat frameworks developed specifically for bryophytes. These analyses revealed four types of communities influenced by spatio-temporal precipitation patterns, altitude and water chemistry factors, most notably calcium and manganese. Community types are compositionally differentiated, although they share some core taxa and show an overall tendency to have several temperate and exclusively aquatic taxa despite the intermittent nature of water flow in highly seasonal Mediterranean rivers. The modelling approach can be improved at a more local scale when more bryological data and higher-resolution environmental information become available. Given future scenarios of climate change and human alteration of hydrological regimes, broader scales studies are needed to monitor shifts in bryophyte communities.

Chrysophytes from some lakes and peat-bogs in the eastern Pyrenees, Catalonia (Spain)

The results of a phycological study on the chrysophyte flora in the eastern Pyrenees (Catalonia, Spain) are presented. The studied area is located between 1600 and 2600 m above sea level, on primarily acid substrate. A total of 34 taxa have been identified, 25 of which are new or very rarely known in Spain. Information about the cell morphology and ecological data of the studied aquatic systems are presented.