Activity, distribution and microhabitat use by the imperilled mira chub Squalius Torgalensis

Tese de doutoramento, Biologia (Ecologia), Universidade de Lisboa, Faculdade de Ciências, 2014Understanding habitat selection and use by stream fishes increasingly requires the analysis of the relationships between fish and their environments in terms of individual fitness. However, such mechanistic approaches are still uncommon for cyprinids, and remain to be evaluated and tested for Mediterranean species. This thesis addressed activity, distribution and microhabitat use by Mira chub Squalius torgalensis, an imperilled cyprinid native to Mediterranean streams in SW Portugal. This was analysed using a mechanistic approach, including direct observations of fish and habitat in two reaches of the Torgal stream, in spring 2009 and 2010, and laboratory experiments on foraging success under variable velocities. Daily activity patterns were variable at the individual level and shaped by extrinsic and intrinsic factors. Foraging changed from drift to benthic on an annual-basis and with shoal size, and time spent cruising vs. searching was influenced by temperature and body size. Chub displayed an aggregated distribution apparently in association with patchily distributed and autocorrelated physical resources, such as debris, roots and aquatic vegetation. Microhabitat use was influenced by substrata, cover and depth, but random at the focal level, and little variable throughout ontogeny. Contrary to expectations, microhabitat use was generally unrelated to velocity, probably because prey capture success was high at the low velocities prevailing in study reaches. Nevertheless, the proportion of fish capturing prey and capture success decreased at high velocities. Results indicate that chub may display high flexibility in activity and habitat use, which may be important to cope with the high variability of physical conditions in Mediterranean streams, with maintenance of patches with variable substrata, cover and depth likely favouring local persistence. Moreover, this thesis shows that mechanistic fitness-based criteria may be crucial for understanding habitat selection by Mediterranean cyprinids.Fundação para a Ciência e a Tecnologia (FCT

Determinação das Propriedades Magnéticas de Aços Elétricos em Serviço e Utilizando o Método de Epstein

Os aços elétricos são uns dos materiais mais utilizados, nos mais diversos ramos da indústria. A necessidade deste tipo de material torna incontornável a obrigatoriedade de conhecer/definir as suas propriedades magnéticas. Tais características são contrabalançadas com o objetivo fundamental de obter para os dispositivos que se usam um rendimento cada vez mais elevado, devido às suas utilizações em dispositivos de potência tais como transformadores e máquinas elétricas. Neste trabalho determinam-se as principais propriedades magnéticas de alguns aços elétricos, tais como as perdas magnéticas específicas, as quais são muito importantes para a determinação do rendimento dos dispositivos de potência. Existem diversos tipos de ensaios que podem ser realizados para medição das perdas magnéticas e curvas de magnetização em aços elétricos porém, nesta dissertação apenas se optou por abordar dois desses processos, o método de Epstein – sendo este o método mais aceite pelos diversos comités internacionais de eletrotecnia, apresentando elevada reprodutibilidade nas medições magnéticas – e, o processo no qual se medem as propriedades magnéticas do material usando um núcleo de transformador. Comparam-se assim as características magnéticas de vários aços elétricos obtidas com o aparelho de Epstein com aquelas que se obtém para os mesmos materiais mas ao funcionarem como núcleos de transformadores

Historical food-web changes in invaded fish communities in the lower Guadiana basin

Freshwater ecosystems are increasingly being reshaped by biological invasions, leading to biotic homogenization and biodiversity loss. However, the extent to which novel species may drive changes in food-web structure over time remains poorly understood. Clarifying changes in historical ecological processes is critical to inform conservation and restoration efforts in recipient ecosystems. Here, we address food-web changes associated with fish invasions in the Lower Guadiana Basin (LGB) over the past 40 years, by contrasting feeding relationships between museum-archived and contemporary specimens, using stable carbon (δ13C) and nitrogen (δ15N) ratios. Specifically, trophic niches of museum-archived fishes sampled throughout 1978–1987 and 1999–2004 corresponding to the initial establishment and spread of non-native fishes, respectively, were compared with those of fishes sampled in 2019, characterizing the integration of non-native species in the recipient ecosystem. We focused on five native species (Anaecypris hispanica, Cobitis paludica, Iberochondrostoma lemmingii, Squalius pyrenaicus and Squalius alburnoides) and four non-native species (Lepomis gibbosus, Australo heros facetus, Micropterus salmoides and Gambusia holbrooki) with potential to cover multiple trophic positions in the food-webs. We approached historical baseline resources using prey items in gut con tents of the museum-archived fishes and characterized primary producers and macroinvertebrates in 2019. Prior to analysis, samples were normalized for high lipid content and corrected for preservation. We found considerable asymmetries in niche partitioning among species as invasion progressed. Over time, native species tended to be displaced to lower trophic levels, while non-native species showed significantly higher trophic niches, driven mainly by increases in trophic (δ15N) range. Our study highlights that stable isotopes may provide important insights on historical food-web structure and particularly on processes underpinning ecological changes associated with anthropogenetic pressures on freshwater ecosystems.info:eu-repo/semantics/publishedVersio

Fish communities in the lower Tagus inland wetlands: from anthropogenic pressures to conservation management

Inland wetlands are important biodiversity hotspots and amongst the most impacted ecosystems worldwide. Conservation management and restauration actions in wetlands are thus urgently needed to reverse trends in species loss and habitat degradation, particularly in regions harbouring already endangered endemic species. Inland wetlands may play an important role in supporting endemic endangered fishes in the Lower Tagus basin, where anthropogenic pressures have been increasing, but there is a lack of studies on fish communities, and few areas are identified as inland wetlands. Here, we aim to identify small inland wetlands in the Lower Tagus River and their potential role in supporting fish species, constituting the first study to identify and evaluate the most important fish communities. Inland wetlands were identified through the usage of remote sensing techniques and the calculation of a Normalized Difference Water Index (NDWI) with Sentinel-2 imagery for the Lower Tagus region. From a total of 486 locations identified, 31 were recognized as wetlands as having potential to host fish communities, with 11 being selected for sampling after in loco assessment. Fish sampling was conducted between 6 May and 11 June 2021. Furthermore, for each wetland, we evaluated anthropogenic stressors and land use changes between 2007 and 2018, using national land use data (i.e., Carta de Uso e Ocupação do Solo). A total of 7727 fishes from eight non-native and five native species were captured. Overall, fish communities were dominated by non-native species (97% catches), but both European eel (Anguilla anguilla) and Lisbon arched-mouth nase (Iberochondrostoma olisiponense), which are globally classified as critically endangered (CR), were found in at least two wetlands. Our results suggest that, over the last 10 years, intensive agriculture decreased (on average ≈ 3%) in the areas surrounding these wetlands, being replaced by extensive agriculture or natural uses. Despite non-native fish prevalence, some wetlands may act as refuge habitats for CR fish species. These results are important for guiding the restoration of inland wetlands and promoting conservation management actions to help reverse fish diversity loss.info:eu-repo/semantics/publishedVersio

Corrigendum to ‘a horizon scan exercise for aquatic invasive alien species in Iberian inland waters’

info:eu-repo/semantics/publishedVersio

Habitat selection and foraging success by an endangered Mediterranean cyprinid: implications for habitat restoration

Habitat loss and degradation are causing collapses in freshwater fish in the Mediterranean region, where habitat restoration actions are still hampered by poor understanding of fish habitat selection and fitness. Here, we combined field surveys and laboratorial experiments to investigate how water velocity, body size and intra-specific interactions influence habitat selection and foraging success by the highly endangered Mira chub Squalius torgalensis. Velocity negatively affected habitat selection and fitness of chub via its negative effects on prey capture rate. Small chub occupied lower velocity ranges than large chub, and both captured the most prey at the range of velocities selected in the stream. Size-based intra-specific interactions also affected capture success, with small chub capturing proportionally less prey in the presence of large chub. Our results suggest that, during base-flow conditions, restoring low and moderate velocities up to 26 cm/s will help ensure suitable habitat and improve the fitness of small and large chub occurring in interacting groups. Integrated approaches uncovering factors directly related to habitat selection and individual fitness should guide habitat restoration for fish in Mediterranean streams and may help identify critical habitat features for other endangered species.info:eu-repo/semantics/publishedVersio

The ecological role of permanent ponds in Europe: a review of dietary linkages to terrestrial ecosystems via emerging insects

Permanent ponds are valuable freshwater systems and biodiversity hotspots. They provide diverse ecosystem services (ES), including water quality improvement and supply, food provisioning and biodiversity support. This is despite being under significant pressure from multiple anthropogenic stressors and the impacts of ongoing global change. However, ponds are largely overlooked in management plans and legislation, and ecological research has focused on large freshwater ecosystems, such as rivers or lakes. Protection of ponds is often insufficient or indirectly provided via associated habitats such as wetlands. This phenomenon is likely exacerbated due to lacking a full-scale understanding of the importance of ponds. In this review, we provided a detailed overview of permanent ponds across Europe, including their usages and the biodiversity they support. By discussing the concepts of pondscape and metacommunity theory, we highlighted the importance of connectivity among and between ponds and identified fluxes of emerging insects as another ES of ponds. Those insects are rich in essential nutrients such as polyunsaturated fatty acids (PUFA), which are delivered through them to the terrestrial environment, however the extent and impact of this ES remains largely unexplored. Several potential stressors, especially related to ongoing global change, which influence pond diversity and integrity were discussed. To conclude this review, we provided our insights on future pond management. Adaptive measures, taking into account the pond system per se within the pondscape, were found to be the most promising to mitigate the loss of natural ponds and restore and conserve natural small water bodies as refuges and diversity hotspots in increasingly urbanized landscapes

The ecological role of permanent ponds in Europe ::a review of dietary linkages to terrestrial ecosystems via emerging insects

Permanent ponds are valuable freshwater systems and biodiversity hotspots. They provide diverse ecosystem services (ES), including water quality improvement and supply, food provisioning and biodiversity support. This is despite being under significant pressure from multiple anthropogenic stressors and the impacts of ongoing global change. However, ponds are largely overlooked in management plans and legislation, and ecological research has focused on large freshwater ecosystems, such as rivers or lakes. Protection of ponds is often insufficient or indirectly provided via associated habitats such as wetlands. This phenomenon is likely exacerbated due to lacking a full-scale understanding of the importance of ponds. In this review, we provided a detailed overview of permanent ponds across Europe, including their usages and the biodiversity they support. By discussing the concepts of pondscape and metacommunity theory, we highlighted the importance of connectivity among and between ponds and identified fluxes of emerging insects as another ES of ponds. Those insects are rich in essential nutrients such as polyunsaturated fatty acids (PUFA), which are delivered through them to the terrestrial environment, however the extent and impact of this ES remains largely unexplored. Several potential stressors, especially related to ongoing global change, which influence pond diversity and integrity were discussed. To conclude this review, we provided our insights on future pond management. Adaptive measures, taking into account the pond system per se within the pondscape, were found to be the most promising to mitigate the loss of natural ponds and restore and conserve natural small water bodies as refuges and diversity hotspots in increasingly urbanized landscapes

A multi-taxa assessment of aquatic non-indigenous species introduced into Iberian freshwater and transitional waters

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 by biological invasions. Following a structured approach that combines a systematic review of available information and expert opinion, we provide a comprehensive and updated multi-taxa inventory of aquatic NIS (fungi, macroalgae, vascular plants, invertebrates and vertebrates) in Iberian inland waters. Moreover, we assess overall patterns in the establishment status, introduction pathways, native range and temporal introduction trends of listed NIS. In addition, we discuss the legal coverage provided by both national (Spanish and Portuguese) and European NIS regulations. We inventoried 326 aquatic NIS in Iberian inland waters, including 215 established, 96 with uncertain establishment status and 15 cryptogenic taxa. Invertebrates (54.6%) and vertebrates (24.5%) were the groups with the highest number of NIS, with Arthropoda, Mollusca, and Chordata being the most represented phyla. Recorded NIS originated from diverse geographic regions, with North and South America being the most frequent. Vertebrates and vascular plants were mostly introduced through intentional pathways (i.e. release and escape), whereas invertebrates and macroalgae arrived mostly through unintentional ways (i.e. contaminant or stowaway). Most of the recorded NIS were introduced in Iberian inland waters over the second half of the 20th century, with a high number of NIS introductions being reported in the 2000s. While only 8% of the recorded NIS appear in the European Union list of Invasive Alien Species of Union concern, around 25% are listed in the Spanish and Portuguese NIS regulations. This study provides the most updated checklist of Iberian aquatic NIS, meeting the requirements set by the EU regulation and providing a baseline for the evaluation of its application. We point out the need for coordinated transnational strategies to properly tackle aquatic invasions across borders of the EU members