Effects of small hydropower plants on fish assemblages in medium‐sized streams in central and northern Portugal

• 1. Over the last decade the development of small hydropower projects has been one of the most active areas of the energy sector. One of the main environmental challenges faced by such projects is related to fish passage.
• 2. The impact of 18 small hydropower plants (SHPs) with distinct levels of fish‐pass effectiveness was investigated in the summers of 1998 and 1999 by comparing fish assemblage composition and structure at 36 sites, above and below SHPs.
• 3. With regard to effectiveness, it was estimated that eight (44.4%) of the surveyed passage facilities were suitable for target species, whereas the remaining 10 (55.6%) were considered unsuitable. In neither case did the composition of fish assemblages upstream and downstream from SHPs differ significantly, while assemblage similarity was relatively high.
• 4. Multivariate techniques identified cover, depth and coarse substrate as the main parameters structuring fish assemblages. It is suggested that these variables have created a rich, patchy, heterogeneous habitat, thereby providing satisfactory resources and favourable conditions required by fish and contributing to the maintenance of assemblages.
• 5. Although populations of some species that occurred both upstream and downstream from SHPs have developed differences in their size structures, SHP‐induced fragmentation of fish populations may not necessarily result in genetic divergence among semi‐isolated populations.

Copyright © 2006 John Wiley & Sons, Ltd.     

Detection of Ehrlichia canis by polymerase chain reaction in dogs from Portugal

Antibodies against Ehrlichia canis, the cause of canine monocytic ehrlichiosis, have been reported previously in clinically ill and stray dogs from Portugal. In this study, the 16S rRNA gene of E. canis was detected by the polymerase chain reaction (PCR) in 12/55 (22%) of dogs with suspected tick-borne disease in the Algarve region in Portugal.     

Indicator taxa of spider (Araneae) diversity and their efficiency in conservation

A considerable number of alternative approaches have been suggested during the last years to predict species richness of a given taxon, while retaining information on the identities of the observed individuals. Such information can be extremely useful for choosing conservation priority areas, either by using raw richness values or, preferentially, by considering the complementarity between potential sites. Among the most popular approaches is the use of indicator taxa. Both one single family and a group of several families are here tested in their ability to predict the number of spider (Araneae) species independently of sampling effort, geographical location and type of habitat. We use data from three Portuguese protected areas as a test case. A two-family indicator group – Gnaphosidae and Theridiidae – is found to be a good surrogate of species richness, even if caution is needed regarding the comparison of sites with considerably different sampling effort or vegetation cover. No single family can be seen as a good surrogate of the totality of spiders. In addition, only a group of the two mentioned families is found to be efficient and reliable either when used to rank sites according to taxa richness or for determining near-minimum sets of sites for conservation. We therefore recommend surrogacy with this indicator group as a promising approach for the prediction of spider species richness or evaluation and ranking of areas according to their conservation importance. The reached conclusions should uphold for Portugal and the entire Mediterranean region.     

Analysis of 2735 canine uroliths in Spain and Portugal. A retrospective study: 2004-2006

The objective of the study was to evaluate epidemiological data derived from 2735 canine uroliths received by Hill’s Pet Nutrition from Spain and Portugal between January 2004 and December 2006. The results of quantitative analysis from Minnesota Urolith Center (MUC) were compared with that from other countries and interrelations of mineral composition, age, breed, and gender were determined. The most frequent calculus was calcium oxalate (38.1%) followed by struvite (32.9%). Eighty-three breeds plus crossbreeds (25%) were identified. In all of them, but Dalmatians, calcium oxalate and struvite accounted for 71–78%. The mean age of urolith appearance was 7.6 years. There was a significant difference in the frequency of different uroliths composition among the six most common breeds presenting urolithiasis in Spain and Portugal (Yorkshire terrier, Miniature Schnauzer, Cocker Spaniel, Poodle, Shih Tzu and Dalmatian). This is the first report on xanthine urolithiasis found in Spain. Prevalence of cystine calculi was significantly lower (3.2%) than that reported previously in parts of Spain (26%).     

Tree type and forest management effects on the structure of stream wood following wildfires

Wildfires are an increasingly common disturbance influencing wood recruitment to streams, and thereby affecting their physical and biological condition. Mediterranean countries such as Portugal, where more than 25% of the land area has burned since 1990, are ideal areas to study impacts of wildfire effects on streams. We evaluated the physical structure of 2206 downed wood pieces (DWP) across 27 first- to third-order streams in central Portugal, all of which had experienced recent wildfires. The streams flowed through monospecific upland forests of Eucalyptus, Maritime pines, or Cork oaks and were fringed by a mixture of riparian tree species. DWP structure differed between tree types and between burned and unburned pieces. Post-fire timber-production forests (Maritime pines and Eucalyptus) contributed a higher quantity of thinner, longer and straighter DWP to streams than Cork oak stands. Pieces from Maritime pines had more rootwads and branches than DWP from the other tree types. Pieces from Cork oak and riparian species generally had a bent form, were shorter and had no rootwads. Burned DWP in streams were often from riparian trees. Relative to unburned DWP, the burned DWP occurred more frequently, were larger and straighter, had branches less often, and were more decayed. With more complex branches, rootwads, and a larger diameter, inputs from burned Maritime pine forests are more likely to change stream hydraulics and habitat complexity, relative to inputs from Eucalyptus forests with their simpler structure. This study shows that, less than a decade after wildfires, structure of downed wood in and near streams is strongly influenced by wildfire, but also still reflects intrinsic species characteristics and respective silviculture practices, even after the effects of fire have been accounted for. Under an anticipated shift in landscape cover with higher shrubland proportions and more mixing of Maritime pine and Eucalyptus forests, our results suggest that instream large wood will become scarcer and more structurally homogeneous.     

Importance of recreational fisheries in the Guadiana River Basin in Portugal

The rapid expansion of recreational fishing in Portugal over the last 20 years, along with the multiplicity of pressures affecting inland fisheries, demands the urgent recognition of the social and economic values. Sport-angling information is still inadequate to formulate management actions. To address this issue, a regional survey on freshwater recreational fishing in all the municipalities of the Guadiana River Basin was carried out in 1999. The survey, based on 1998 data, provided information on the profile of anglers, preferences as regards reservoirs and sections of rivers fished, frequency of fishing trips, motivation, expenditure, fish species caught, an estimation of total catch and its destination, interest in competitions, enforcement and personal opinions. The results recommended improved communication and feedback between users, and mechanisms for future regional development and management of recreational fisheries.     

Diet composition of largemouth black bass, Micropterus salmoides (Lacepède), in southern Portuguese reservoirs: its relation to habitat characteristics

Abstract  During the summer of 1990 the diet of Micropterus salmoides (Lacepède) was studied in four southern Portuguese reservoirs. The dominant food items were insects (especially Odonata and Ephemeroptera naiads, and Odonata and Hemiptera adults), the crayfish, Procambarus clarkii (Girard), and pumpkinseed sunfish, Lepomis gibbosus (L.). There was an increase in the consumption of L. gibbosus as bass changed from 100–200 mm total length to over 200 mm, and a corresponding decline in the insect and crayfish components. Carp, Cyprinus carpio L., and other benthic cyprinids were absent from the stomach contents. The association between the different prey consumed and the habitat characteristics are discussed in relation to the feeding ecology of largemouth bass, an exotic species in Portugal.     

Microhabitat use by Iberian nase Chondrostoma polylepis and Iberian chub Squalius carolitertii in three small streams, north-west Portugal

Abstract –  Microhabitat use of Iberian nase Chondrostoma polylepis (Steindachner 1865) and Iberian chub Squalius carolitertii (Doadrio 1988) was studied in three small streams of the Lima basin, north-west Portugal. Measurements were made for 210 and 248 individuals, respectively, distributed in two size classes, based on fish ages, during winter, spring, summer and autumn 1998. Both species moved to shallow and slow-flowing microhabitats in summer and autumn, but this mainly reflected seasonal variation in microhabitat availability. Larger individuals of both species used deeper and lower percentage cover areas than smaller conspecifics, however significant ontogenetic differences were only found for water velocity. Different patterns of nonrandom microhabitat use were displayed by both cyprinids. Larger I. nase were in deeper and more discovered waters than those available in the habitat, whereas I. chub was over-represented in slow-flowing areas. There was no evidence of interspecific competition for microhabitat, therefore it is unlikely that spatial resource was limited during the present study.     

A simple method for assessing minimum flows in regulated rivers: the case of sea lamprey reproduction

• 1. The sea lamprey (Petromyzon marinus) is an anadromous species that occurs in some large Iberian rivers, such as the Tagus, and their tributaries. The sea lamprey populations of the River Tagus are threatened by habitat loss and overexploitation, which means that conservation measures, including maintenance of the spawning grounds, are urgent. Habitat loss is mainly due to hydroelectric and flood‐control dams that have affected the migration and spawning habitats of anadromous species. The main objective of this study was to use a simple, cost‐effective method to assess a minimum instream flow for the regulated River Tagus. The method used was based on the wetted perimeter–discharge relationship, but accounted for the habitat requirements of spawning sea lampreys.
• 2. In 1998, a habitat survey was conducted along a 30 km segment of the River Tagus downstream from Belver Dam (the first impassable obstacle for fish movements), a stretch that includes potential habitats for spawning sea lampreys. Four spawning areas were identified, and in each one a representative reach was selected along which to collect elevation and geo‐positional data. For a range of flows from 0 to 50 m³ s^?1, hydraulic modelling and studies of spawning habitat availability were conducted, both for each reach and for the total wetted area of the four reaches.
• 3. The availability of spawning habitat was limited by flow. Results showed that the present minimum flow downstream from Belver Dam (8 m³ s^?1) is insufficient to ensure suitable habitat conditions in a significant part of the segment studied; gains in wetted usable area were more substantial with discharges of up to 20 m³ s^?1, and thus a minimum flow of 10–20 m³ s^?1 was recommended. Potential spawning habitat could be improved by increasing instream flow to at least 50 m³ s^?1. The impacts of the Belver release regime on anadromous species are discussed and a more ‘ecologically oriented’ form of water management is suggested

. Copyright © 2004 John Wiley & Sons, Ltd.