Maria João Feio

The Iberian Rivers

This chapter highlights that Iberian rivers are naturally rich in terms of their biota. The biological richness in Iberian inland waters is under threat because of the high number of biological invasions. For example, the river Ebro has been invaded by the molluscs D. polymorpha and C. fluminea , but also by the fishes S. glanis and Ictalurus melas in its lower course. These invasions have resulted in a decrease in habitat diversity and in the number of native species. Water transfer between basins is a constant issue in the different hydrological plans that the governments develop to satisfy the high water demands and which would increase the possibility for species invasion. The management of rivers and their associated disturbance regimes has a cultural or societal component. The human presence and management of watercourses may have very different affects depending on the cultural perception of rivers. People in arid and semi-arid regions have the least respect toward rivers since the rivers are often dry or have catastrophic floods and are, therefore, viewed more as a danger than as a natural resource to be preserved. Moreover, there is a well-rooted perception that any water that reaches the sea is wasted. The chapter suggests that this perception being difficult to change, the progressive implementation of the Water Framework Directive (WFD) in the different basins will hopefully force a change in attitude toward the rivers as well as the required administrative steps to secure their conservation and sound management.

Diatoms and macroinvertebrates provide consistent and complementary information on environmental quality

Predictive models based on invertebrate assemblages are a powerful tool for assessing water quality. Yet, few attempts have been made to build predictive models with diatoms although they are widely used in freshwater assessment and are among the mandatory biological monitoring elements indicated in the European Water Framework Directive. We built two predictive models for central Portugal, one for macroinvertebrates and the other for diatoms, using data sampled simultaneously from 43 sites in the Spring of 2004 and 2005. Our objective was to test the performance of models based on the diatom community and compare the assessments made by the two indicator communities for the same sites. Each model was tested with 17 sites. Both models showed good performance in predicting reference sites to the correct group: 76 % for the macroinvertebrate model using the discriminant variables longitude, distance to source, alkalinity, depth, number of riffles and channel substrate diversity; 85 % for the diatoms model using latitude, runoff, mineralization, distance to source, slope, discharge and hardness. The water quality assessments of test sites produced by the two models were similar in 76 % of the cases. According to the predictive models, invertebrates were more sensitive to morphological alterations of the channel and habitat conditions (presence of dams and artificial walls, destruction of riparian corridor) while diatoms were more sensitive to changes in water chemistry. Moreover, in lowland streams, where the habitat and substrate heterogeneity are naturally low, assessment by diatoms was more useful than evaluations using invertebrates. We concluded that invertebrates and algae provide consistent and in some cases complementary information on environmental quality and recommend their simultaneous use for bioassessment.

The influence of extreme climatic events and human disturbance on macroinvertebrate community patterns of a Mediterranean stream over 15 y

Abstract We analyzed long-term changes in macroinvertebrate communities in a Mediterranean temporary stream in southern Portugal over 15 y (1993–2008) at 10 locations with 3 degrees of physicochemical disturbance (reference, high disturbance, and mild disturbance). We related year-to-year variation of macroinvertebrate communities to long-term (59 y) information on precipitation and temperature. Our goals were to: 1) determine the stability of macroinvertebrate communities in the stream, 2) establish the influence of physicochemical disturbance on community stability, 3) assess the influence of climate change on the macroinvertebrate communities, and 4) assess the interactive effects of climate change and disturbance level on macroinvertebrate communities. Community structure varied naturally from year to year, but changes in taxon richness and evenness were much stronger and more unpredictable in disturbed than in other sites. In the long term, the more diverse (reference) and the poorest (disturbed) communities were stable, whereas communities affected by mild disturbance slowly decreased in taxon richness (slope  =  −0.07, r2  =  0.38). This decrease could be a response to the continuous stress or to climate change. The multivariate patterns over time of invertebrate communities at mildly disturbed sites were the only patterns significantly correlated with climatic patterns. In the past 59 y in this Mediterranean area (southeastern Europe), winter temperature has increased 1°C and precipitation has decreased 1.5 mm/d. Marked changes in community composition (70–80% Bray–Curtis dissimilarity) occurred only in years of extremely low precipitation or temperature. In years of climatic extremes and at chemically disturbed sites, Orthocladiinae and Simuliidae became dominant. In this stream, a shift in community equity occurs before species elimination. This shift might be useful as an early warning for biodiversity loss because of disturbance or climate change. We recommend continued sampling of reference sites for monitoring purposes so that effects of climate change can be established and so that contemporary human disturbance can be assessed relative to an adjusted reference condition.

Food consumption by the larvae of Sericostoma vittatum (Trichoptera), an endemic species from the Iberian Peninsula

The caddisfly Sericostoma vittatum Rambur (Trichoptera: Sericostomatidae) is an endemic species of the Iberian Peninsula. Under laboratory conditions, larvae of S. vittatum had a higher activity and metabolism during the night. Besides consuming particulate allochthonous organic matter, young stages are also able to feed and grow on faecal pellets from adults. Daily growth rates varied from 0.02 mg (0.8–3.7 mg size class animals) to 0.31 mg dry mass (10.6–22.8 mg size class animals). Due to the high densities of this species (annual mean of 25 individuals m−2; maximum of 96 individuals m−2) and high consumption rates (0.47 mg leaf dry mass mg animal−1 d−1for small larvae), this species has a potential key role on the fragmentation of allochthonous organic matter of streams in central Portugal.

A predictive model for freshwater bioassessment (Mondego River, Portugal)

We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model. At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207 taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality, substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model, the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and increasing the number of ellipses that define quality bands.

Comparability of ecological quality boundaries in the Mediterranean basin using freshwater benthic invertebrates. Statistical options and implications

Within the Mediterranean region each country has its own assessment method based on aquatic macroinvertebrates. However, independently of the classification system, quality assessments should be comparable across members of the European Commission, which means, among others, that the boundaries between classes should not deviate significantly. Here we check for comparability between High-Good and Good-Moderate classifications, through the use of a common metric. Additionally, we discuss the influence of the conceptual and statistical approaches used to calculate a common boundary within the Mediterranean countries participating in the Intercalibration Exercise (e.g., using individual national type-boundaries, one value for each common type or an average boundary by country; weighted average, median) in the overall outcome. All methods, except for the IBMWP (the Iberian BMWP) when applied to temporary rivers, were highly correlated (0.82<R<0.98) with the common metric STAR-ICMi. This index was shown to respond well to a variety of pressures (especially local habitat alterations, riparian vegetation degradation, nutrient enrichment and chemical contamination, land use and global degradation; p<0.00001) affecting Mediterranean streams. However, depending on the statistical approach used, a different number of class boundaries failed the acceptable deviation from the common boundary (a quarter of class width). That leads to a different percentage of national sites failing to achieve good status and ultimately to a different technical and economic effort in the recovery of streams to that condition. We argue that low/high boundaries might have different meanings not restricted to the quality (good/bad) of reference conditions but also to the natural spatial and temporal variability contained in national and intercalibration types. The highly variable hydrological regimes of Mediterranean streams may influence the reference condition and require further investigation.

The Skin Secretion of the Amphibian Phyllomedusa nordestina: A Source of Antimicrobial and Antiprotozoal Peptides

Antimicrobial peptides (AMPs) from the dermaseptin and phylloseptin families were isolated from the skin secretion of Phyllomedusa nordestina, a recently described amphibian species from Northeastern Brazil. One dermaseptin and three phylloseptins were chosen for solid phase peptide synthesis. The antiprotozoal and antimicrobial activities of the synthetic peptides were determined, as well as their cytotoxicity in mouse peritoneal cells. AMPs are being considered as frameworks for the development of novel drugs inspired by their mechanism of action.

Macroinvertebrate short-term responses to flow variation and oxygen depletion: A mesocosm approach

In Mediterranean rivers, water scarcity is a key stressor with direct and indirect effects on other stressors, such as water quality decline and inherent oxygen depletion associated with pollutants inputs. Yet, predicting the responses of macroinvertebrates to these stressors combination is quite challenging due to the reduced available information, especially if biotic and abiotic seasonal variations are taken under consideration. This study focused on the response of macroinvertebrates by drift to single and combined effects of water scarcity and dissolved oxygen (DO) depletion over two seasons (winter and spring). A factorial design of two flow velocity levels - regular and low (vL) - with three levels of oxygen depletion - normoxia, medium depletion (dM) and higher depletion (dH) - was carried out in a 5-artificial channels system, in short-term experiments. Results showed that both stressors individually and together had a significant effect on macroinvertebrate drift ratio for both seasons. Single stressor effects showed that macroinvertebrate drift decreased with flow velocity reduction and increased with DO depletion, in both winter and spring experiments. Despite single stressors opposing effects in drift ratio, combined stressors interaction (vL×dM and vL×dH) induced a positive synergistic drift effect for both seasons, but only in winter the drift ratio was different between the levels of DO depletion. Stressors interaction in winter seemed to intensify drift response when reached lower oxygen saturation. Also, drift patterns were different between seasons for all treatments, which may depend on individuals life stage and seasonal behaviour. Water scarcity seems to exacerbate the oxygen depletion conditions resulting into a greater drifting of invertebrates. The potential effects of oxygen depletion should be evaluated when addressing the impacts of water scarcity on river ecosystems, since flow reductions will likely contribute to a higher oxygen deficit, particularly in Mediterranean rivers.

From perennial to temporary streams: an extreme drought as a driving force of freshwater communities

Alterations in trait proportions of diatom and aquatic macroinvertebrate communities were used to evaluate the consequences of the drying of temperate perennial streams due to an uncommon drought event. Four Atlantic-temperate Portuguese streams were sampled on three occasions; spring before the drought, 2 weeks after the return of water to the streambed, and spring after the drought. The traits from diatom and macroinvertebrate communities from temperate streams were also compared with those from Mediterranean systems to assess possible shifts in traits. The effects from stream drying were long-lasting for macroinvertebrates; however, only the diatom trait proportions shifted towards proportions similar to those occurring in Mediterranean streams. There was a significant reduction of macroinvertebrates with the ability to produce cocoons, to disperse actively by flight and passively disperse in the water and of swimmers following the return of water. A decrease in stalked species immediately after drought was evident in diatom communities. In contrast to temperate communities, Mediterranean ones were characterised by larger and less mobile diatoms, and smaller-bodied macroinvertebrates with shorter life cycles. Additional studies are required to determine the long-term effect of uncharacteristic drought events on biological traits and their ecosystem functions in typically perennial streams.

Can season interfere with diatom ecological quality assessment

To understand whether seasons influence the ecological quality assessment of streams on the basis of diatoms, a study was undertaken in two lowland water courses located in northwest Portugal, between autumn 2008 and summer 2009. Temporal variation in the chemical pollution of these streams was small as revealed by a number of physical and chemical parameters analyzed. PERMANOVA global test revealed significant variation in water temperature among seasons. The diatom communities also showed a temporal variation although not all the seasons were statistically different. The multidimensional scaling analysis showed that the main differences in the diatom communities were between two groups of seasons: autumn/winter and spring/summer. Species such as Cocconeis pseudolineata, Gomphonema parvulum var. exilissimum, Fragilaria vaucheriae, Encyonema minutum, and Nitzschia recta were more abundant in spring/summer, while species such as Mayamaea atomus and Nitzschia pusilla were more abundant in autumn/winter. The BIOENV routine confirmed that the biological and temperature patterns are highly correlated. Despite the effects observed on diatom communities, these differences were buffered by the EQR (IPS) values which do not reflect seasonal differences. Therefore, the use of the index IPS seems to allow the monitoring of the streams’ ecological quality throughout the year without the interference of the natural temporal variability of diatom communities.