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1.
Environ Monit Assess ; 196(6): 578, 2024 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-38795160

RESUMO

Monitoring water quality and quantity is crucial to be sure that water resources are sustainably used. However, there is no monitoring system of water quantity and quality in southwestern Ethiopia, despite expansion of agricultural activities demanding water resources. The objective of this study was to investigate the effect of agriculture on water quantity and quality with special emphasis on irrigation in southwestern Ethiopia. Data of water quantity was collected from four rivers and four irrigation canals during dry season of 2023. Physico-chemical water quality data was collected from 35 sites. Water quantity was calculated by estimating the water discharge of the rivers and irrigation canals. Weighted arithmetic water quality index was calculated to assess the status of the studied rivers. Principal component analysis was used to identify the relation of the sites with water quality parameters. This study revealed that the average amount of abstracted water for irrigation from the four studied rivers was 22,399 m3/day during the studied period, and the average percentage of abstracted water was 17%. Sites downstream of the irrigation site were characterized by poor water quality compared with the upstream sites. Sites surrounded by agricultural land use were correlated with chemical oxygen demand, electric conductivity, nitrate, orthophosphate, water temperature, and pH, whereas all sites surrounded by forest were positively correlated with dissolved oxygen. This study indicates that agricultural activities have a negative impact on surface water quality and quantity if not managed properly. Hence, we recommend sustainable use of water resources for the planned irrigation expansion.


Assuntos
Agricultura , Monitoramento Ambiental , Rios , Qualidade da Água , Etiópia , Rios/química , Irrigação Agrícola , Poluentes Químicos da Água/análise , Abastecimento de Água/estatística & dados numéricos , Nitratos/análise
2.
Echocardiography ; 41(5): e15825, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38690622

RESUMO

Adaptation of the heart is often a blessing for the patient, but sometimes a diagnostic challenge for the responsible physician. The clinical difficulty may be enhanced when employing diagnostic tools that are hard to interpret. Ratio-based metrics are notorious in this respect, and particularly risky in the follow-up evaluation of heart transplant patients. However, measures expressed as physical units contribute to a comprehensive clinical evaluation and guide proper patient management.


Assuntos
Transplante de Coração , Humanos , Ecocardiografia/métodos , Seleção de Pacientes
3.
Plants (Basel) ; 13(7)2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38611543

RESUMO

Streams are biodiversity hotspots that provide numerous ecosystem services. Safeguarding this biodiversity is crucial to uphold sustainable ecosystem functioning and to ensure the continuation of these ecosystem services in the future. However, in recent decades, streams have witnessed a disproportionate decline in biodiversity compared to other ecosystems, and are currently considered among the most threatened ecosystems worldwide. This is the result of the combined effect of a multitude of stressors. For freshwater systems in general, these have been classified into five main pressures: water pollution, overexploitation, habitat degradation and destruction, alien invasive species, and hydromorphological pressures. On top of these direct stressors, the effects of global processes like environmental and climate change must be considered. The intricate and interconnected nature of various stressors affecting streams has made it challenging to formulate effective policies and management strategies. As a result, restoration efforts have not always been successful in creating a large-scale shift towards a better ecological status. In order to achieve an improved status in these systems, situation-specific management strategies tailored to specific stressor combinations may be needed. In this paper, we examine the potential of introducing native submerged macrophyte species to advance the restoration of stream ecosystems. Through successful introductions, we anticipate positive ecological outcomes, including enhanced water quality and increased biodiversity. This research is significant, as the potential success in restoring stream biodiversity not only represents progress in ecological understanding but also offers valuable insights for future restoration and management strategies for these vital ecosystems.

4.
Echocardiography ; 41(4): e15797, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38549393

RESUMO

Survey of four ratio-based metrics, commonly used to evaluate left ventricular performance. The numerator of each ratio is plotted against the corresponding denominator, implying that the slope of the colored line reflects the value of the ratio.9,11 Similar graphs can be constructed for the other cardiac compartments. Data sets obtained at various altitudes and defined with reference to sea level, based on Rao et al.6 Acronyms: E/A unitless ratio of the early (E) and late (A) diastolic wave peak velocities (cm/s); EDD, end-diastolic diameter (mm); EDV, end-diastolic volume (mL); EF, ejection fraction (%); ESD, end-systolic diameter (mm); ESV, end-systolic volume (mL); FS, fractional shortening (%).


Assuntos
Altitude , Ventrículos do Coração , Humanos , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/anatomia & histologia , Diástole , Volume Sistólico , Função Ventricular Esquerda
6.
Nat Ecol Evol ; 8(3): 430-441, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38278985

RESUMO

Humans impact terrestrial, marine and freshwater ecosystems, yet many broad-scale studies have found no systematic, negative biodiversity changes (for example, decreasing abundance or taxon richness). Here we show that mixed biodiversity responses may arise because community metrics show variable responses to anthropogenic impacts across broad spatial scales. We first quantified temporal trends in anthropogenic impacts for 1,365 riverine invertebrate communities from 23 European countries, based on similarity to least-impacted reference communities. Reference comparisons provide necessary, but often missing, baselines for evaluating whether communities are negatively impacted or have improved (less or more similar, respectively). We then determined whether changing impacts were consistently reflected in metrics of community abundance, taxon richness, evenness and composition. Invertebrate communities improved, that is, became more similar to reference conditions, from 1992 until the 2010s, after which improvements plateaued. Improvements were generally reflected by higher taxon richness, providing evidence that certain community metrics can broadly indicate anthropogenic impacts. However, richness responses were highly variable among sites, and we found no consistent responses in community abundance, evenness or composition. These findings suggest that, without sufficient data and careful metric selection, many common community metrics cannot reliably reflect anthropogenic impacts, helping explain the prevalence of mixed biodiversity trends.


Assuntos
Biodiversidade , Ecossistema , Animais , Humanos , Invertebrados , Rios , Europa (Continente)
7.
Biol Rev Camb Philos Soc ; 99(1): 313-327, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37813384

RESUMO

Many fish species depend on migration for various parts of their life cycle. Well-known examples include diadromous fish such as salmon and eels that need both fresh water and salt water to complete their life cycle. Migration also occurs within species that depend only on fresh water. In recent decades, anthropogenic pressures on freshwater systems have increased greatly, and have resulted, among other effects, in drastic habitat fragmentation. Fishways have been developed to mitigate the resulting habitat fragmentation, but these are not always effective. To improve fishway efficiency, the variety of navigation cues used by fish must be better understood: fish use a multitude of sensory inputs ranging from flow variables to olfactory cues. The reaction of a fish is highly dependent on the intensity of the cue, the fish species involved, and individual traits. Recently developed monitoring technologies allow us to gain insights into different combinations of environmental and physiological conditions. By combining fish behavioural models with environmental models, interactions among these components can be investigated. Several methods can be used to analyse fish migration, with state-space models, hidden Markov models, and individual-based models potentially being the most relevant since they can use individual data and can tie them to explicit spatial locations within the considered system. The aim of this review is to analyse the navigational cues used by fish and the models that can be applied to gather knowledge on these processes. Such knowledge could greatly improve the design and operation of fishways for a wider range of fish species and conditions.


Assuntos
Sinais (Psicologia) , Peixes , Animais , Peixes/fisiologia , Água Doce , Ecossistema , Fenótipo
8.
Artigo em Inglês | MEDLINE | ID: mdl-38083068

RESUMO

Noninvasive blood pressure recordings typically focus on systolic blood pressure (SBP) and diastolic pressure (DBP). Derived metrics are often analyzed, e.g. pulse pressure (PP), defined as SBP minus DBP. As the metric PP is not unique, we introduced the PP companion (PPC), calculated using the Pythagorean theorem. PPC is associated with mean arterial pressure (MAP). Another mathematical construct frequently used in hemodynamic studies refers to the ratio of DBP and SBP, denoted as Prat. PP and Prat share the same companion (C). The association between PratC and MAP, as well as the connection between PP and Prat has not been studied in healthy children. We analyzed a large set of daytime (DT) and nighttime (NT) data (N=949, age 5 to 16 years, including 485 girls), published in the literature. Average PP increases with age (in 0.5 year increments), while Prat decreases. Prat vs PP yields R2>0.985 for both DT and NT data, when stratified for boys and girls. PPC is significantly lower (P<0.0001) during the night for both sexes. We conclude that Prat carries no substantial incremental value beyond PP, in contrast to PPC which points to DT/NT, age-dependent and sex-specific differences in these children.Clinical Relevance- Various derived metrics based on blood pressure have been introduced in hemodynamic studies, but not all of them are fully independent. The diastolic to systolic pressure ratio in healthy children is inversely associated with pulse pressure, showing partial sex-specific overlap, but substantial daytime versus night differences.


Assuntos
Pressão Arterial , Caracteres Sexuais , Masculino , Feminino , Criança , Humanos , Pré-Escolar , Adolescente , Pressão Sanguínea/fisiologia , Sinais Vitais , Diástole/fisiologia
9.
Artigo em Inglês | MEDLINE | ID: mdl-38083207

RESUMO

Cardiac resynchronization therapy (CRT) can decrease the risk of heart failure (HF) events in relatively asymptomatic patients with a reduced ejection fraction (EF) and wide QRS complex. However, individual response to this type of therapy varies widely. Often based on either EF increase or end-systolic volume (ESV) decrease as criterion, a subgroup of super-responders has been described. Therefore, it is important to determine factors that can predict a favorable response and identify those patients who may benefit from CRT. With this goal in mind we explored the possible role of ESV.To improve insight in ventricular pump function we previously introduced the volume regulation graph (VRG), relating ESV to end-diastolic volume (EDV). An individual patient is uniquely defined by the prevailing working point in the volume domain. The traditional metric EF can be graphically derived for each working point. The nonlinear association between EF and ESV is given by EF = 1 + γ {ESV / (δ - ESV)}, with empirical constants γ and δ. The impact of CRT super-responders on EF can be evaluated, taking into account sex-specific ESV values. Based on available regression equations we modeled the impact on EF (as percent points) resulting from CRT-induced fractional ESV changes expressed as % of baseline ESV. Our analysis confirms clinical findings, indicating that CRT super-responders are likely to be women, and clarify why a specific reduction of ESV cannot be directly translated into EF improvement. We propose that the EF as CRT criterion should be abandoned and replaced by sex-specific ESV evaluations.Clinical Relevance- Response to CRT should be evaluated in a sex-specific manner. The smaller heart size in women has implications for the interpretation of percentwise reductions of ESV and their translation into an associated increase of EF.


Assuntos
Terapia de Ressincronização Cardíaca , Insuficiência Cardíaca , Disfunção Ventricular Esquerda , Masculino , Humanos , Feminino , Volume Sistólico/fisiologia , Terapia de Ressincronização Cardíaca/métodos , Disfunção Ventricular Esquerda/terapia , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/terapia , Arritmias Cardíacas
10.
Artigo em Inglês | MEDLINE | ID: mdl-38083425

RESUMO

Ejection fraction (EF) is traditionally considered useful to infer ventricular function. Newer metrics such as global function index (GFI) and various strains add supplemental diagnostic or prognostic value. All these candidates refer to dimensionless ratios, rather than to the characteristics of the underlying components. Therefore, we introduced the volume regulation graph (VRG), relating end-systolic volume (ESV) to end-diastolic volume (EDV). An individual patient is then uniquely defined by the prevailing working point in the volume domain. Alternatively, the combination of EF=(1-ESV/EDV) and any suitable companion (denoted as C) metric (e.g. the Pythagorean mean) specifies this working point.An expression relates EF to global longitudinal (GLS) and circumferential strain (GCS): ESV/EDV = (GLS+1) (GCS+1)2, resembling the empirical regression equation for the VRG. However, the latter has a non-zero intercept (mL). The discrepancy can be solved by the introduction of one or more pertinent companion metrics.We studied 96 patients by cardiac magnetic resonance imaging and calculated EF, EFC, GFI, GLS and GCS. The GFI is inversely related to GLS (R2=0.26). For regression we found: ESV=0.74 EDV-27.0 with R2=0.81 for N=96. Similar results were obtained for echocardiography data (N=25). Graphs relating EF to GLS and GCS indicate that EFC can distinguish patients with nearly identical values for these 3 metrics.Thus, the VRG offers a unifying framework that visualizes the association between ESV and EDV, while documenting iso-EF and iso-EFC trajectories. Newer metrics including GFI, GLS and GCS require consideration of a companion variable such as EFC to permit a comprehensive analysis.Clinical Relevance- The VRG allows insight into ventricular functioning and illustrates the working point concept. Companion metrics (having a physical dimension) should be considered in conjunction with any traditional ratio-based index.


Assuntos
Ecocardiografia , Função Ventricular Esquerda , Humanos , Volume Sistólico/fisiologia , Função Ventricular Esquerda/fisiologia , Ventrículos do Coração/diagnóstico por imagem , Função Ventricular
11.
Front Vet Sci ; 10: 1272402, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37929287

RESUMO

Oropharyngeal (OP) and cloacal (CL) swabs from 2049 adult backyard chickens collected at 12 live bird markets, two each in Arusha, Dar es Salaam, Iringa, Mbeya, Morogoro and Tanga regions of Tanzania were screened for Newcastle disease virus (NDV) using reverse transcription real-time PCR (rRT-PCR). The virus was confirmed in 25.23% of the birds (n = 517; rRT-PCR CT ≤ 30), with the highest positivity rates observed in birds from Dar es Salaam region with higher prevalence during the dry season (September-November 2018) compared to the rainy season (January and April-May 2019). Next-generation sequencing of OP/CL samples of 20 out of 32 birds that had high amounts of viral RNAs (CT ≤ 25) resulted in the assembly of 18 complete and two partial genome sequences (15,192 bp and 15,045-15,190 bp in length, respectively) of NDV sub-genotypes V.3, VII.2 and XIII.1.1 (n = 1, 13 and 4 strains, respectively). Two birds had mixed NDV infections (V.3/VII.2 and VII.2/XIII.1.1), and nine were coinfected with viruses of families Astroviridae, Coronaviridae, Orthomyxoviridae, Picornaviridae, Pneumoviridae, and Reoviridae. Of the coinfecting viruses, complete genome sequences of two avastroviruses (a recombinant chicken astrovirus antigenic group-Aii and avian nephritis virus genogroup-5) and two infectious bronchitis viruses (a turkey coronavirus-like recombinant and a GI-19 virus) were determined. The fusion (F) protein F1/F2 cleavage sites of the Tanzanian NDVs have the consensus motifs 112 RRRKR↓F 117 (VII.2 strains) and 112 RRQKR↓F 117 (V.3 and XIII.1.1 strains) consistent with virulent virus; virulence was confirmed by intracerebral pathogenicity index scores of 1.66-1.88 in 1-day-old chicks using nine of the 20 isolates. Phylogenetically, the complete F-gene and full genome sequences regionally cluster the Tanzanian NDVs with, but distinctly from, other strains previously reported in eastern and southern African countries. These data contribute to the understanding of NDV epidemiology in Tanzania and the region.

12.
Braz J Microbiol ; 54(4): 3265-3273, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37907827

RESUMO

Newcastle disease (ND) is among the most important poultry diseases worldwide. It is the major threat to poultry production in Africa and causes major economic losses for both local and commercial chickens. To date, half of ND class II genotypes have been reported in Africa (I, IV, V, VI, VII, XI, XIII, XIV, XVII, XVIII, and XXI). The information on the circulating NDV genotypes is still scarce despite the endemic nature of ND in most countries on the African continent.A total of 659 oro-cloacal swabs were collected from local chickens in Mawenzi live bird market located in Morogoro, Tanzania, between June 2020 and May 2021. Newcastle disease virus was detected by using reverse transcription real-time polymerase chain reaction (RT-qPCR) and conventional PCR followed by sequencing of PCR products. The prevalence of NDV in the surveilled live bird markets was 23.5%. Sequencing and phylogenetic analysis revealed the presence of sub-genotype VII.2. The detected sub-genotype VII.2 has phylogenetic links to Zambian NDV strains implying a Southeast dissemination of the virus, considering that it was first detected in Mozambique. This study underscores the need of active NDV surveillance to determine the distribution of this NDV genotype in the country and monitor its spread and contribution to the emergence of new ND viruses.


Assuntos
Doença de Newcastle , Doenças das Aves Domésticas , Animais , Vírus da Doença de Newcastle/genética , Tanzânia , Filogenia , Galinhas , Doença de Newcastle/epidemiologia , Reação em Cadeia da Polimerase em Tempo Real , Genótipo
13.
Biology (Basel) ; 12(11)2023 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-37997985

RESUMO

High-elevation tropical streams are under increasing threat from human activities and climate change. Specifically, Ecuadorian Andean streams require priority actions such as bioassessment (e.g., biodiversity and functional ecology of macroinvertebrates) in order to generate adequate environmental management policies. Therefore, we investigated the distribution and composition of the macroinvertebrate taxa and their functional feeding groups in relation to the environmental variables in the Antisana river basin (Andean-Ecuadorian Region). We sampled macroinvertebrates from 15 locations to assess ecological conditions (ECs), expressed as the Biological Monitoring Working Party Colombia (BMWP-Col) classes, the Andean Biotic Index (ABI) and the Andean-Amazon Biotic Index (AAMBI). Results indicate that dissolved oxygen saturation, elevation, nutrient concentration and conductivity contributed significantly to the composition of the taxa and functional feeding groups (FFGs). Taxa diversity and FFGs were more abundant in the best EC sites. Shredders (SH) were, overall, dominant and abundant at sites with medium-high ECs. Scrapers constituted the second most prevalent assemblage, exerting dominance at moderate ecological conditions (high altitude and high oxygen saturation). Collector-gathers (CGs) are less sensitive to contamination than the previous two groups but were equally abundant at medium-high EC sites. Collector-filterers (CFs) and parasites (PAs) were less abundant, although the presence of the former was slightly related to better environmental conditions. Predators (PRs) were almost absent throughout the study, but they were collected from poor EC sites. CGs, PAs and PRs showed more tolerance to the presence of human disturbances (e.g., hydraulic constructions or slope erosion). The BMWP-Col index seems to be the best fit for this ecosystem, showing a significant difference in FFG between the index classes, compared to the other indices evaluated. The results of this investigation may be regarded as a fundamental starting point and used in future bioassessment work in other similar ecosystems, particularly high-altitude tropical Ecuadorian streams.

14.
Genes (Basel) ; 14(10)2023 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-37895200

RESUMO

A complete genome sequence of an avian coronavirus (AvCoV; 27,663 bp excluding 3' poly(A) tail) was determined using nontargeted next-generation sequencing (NGS) of an oropharyngeal swab from a backyard chicken in a live bird market in Arusha, Tanzania. The open reading frames (ORFs) of the Tanzanian strain TZ/CA127/19 are organized as typical of gammaCoVs (Coronaviridae family): 5'UTR-[ORFs 1a/1b encoding replicase complex (Rep1ab) non-structural peptides nsp2-16]-[spike (S) protein]-[ORFs 3a/3b]-[small envelop (E) protein]-[membrane (M) protein]-[ORFs 4a/4c]-[ORFs 5a/5b]-[nucleocapsid (N) protein]-[ORF6b]-3'UTR. The structural (S, E, M and N) and Rep1ab proteins of TZ/CA127/19 contain features typically conserved in AvCoVs, including the cleavage sites and functional motifs in Rep1ab and S. Its genome backbone (non-spike region) is closest to Asian GI-7 and GI-19 infectious bronchitis viruses (IBVs) with 87.2-89.7% nucleotide (nt) identities, but it has a S gene closest (98.9% nt identity) to the recombinant strain ck/CN/ahysx-1/16. Its 3a, 3b E and 4c sequences are closest to the duck CoV strain DK/GD/27/14 at 99.43%, 100%, 99.65% and 99.38% nt identities, respectively. Whereas its S gene phylogenetically cluster with North American TCoVs and French guineafowl COVs, all other viral genes group monophyletically with Eurasian GI-7/GI-19 IBVs and Chinese recombinant AvCoVs. Detection of a 4445 nt-long recombinant fragment with breakpoints at positions 19,961 and 24,405 (C- and N-terminus of nsp16 and E, respectively) strongly suggested that TZ/CA127/19 acquired its genome backbone from an LX4-type (GI-19) field strain via recombination with an unknown AvCoV. This is the first report of AvCoV in Tanzania and leaves unanswered the questions of its emergence and the biological significance.


Assuntos
Infecções por Coronavirus , Gammacoronavirus , Vírus da Bronquite Infecciosa , Animais , Galinhas/genética , Gammacoronavirus/genética , Tanzânia/epidemiologia , Genoma Viral , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/veterinária , Infecções por Coronavirus/genética , Vírus da Bronquite Infecciosa/genética
15.
Atherosclerosis ; 384: 117275, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37783644

RESUMO

Asymptomatic atherosclerosis begins early in life and may progress in a sex-specific manner to become the major cause of cardiovascular morbidity and death. As diagnostic tools to evaluate atherosclerosis in the macrocirculation, we discuss imaging methods (in terms of computed tomography, positron emission tomography, intravascular ultrasound, magnetic resonance imaging, and optical coherence tomography), along with derived scores (Agatston, Gensini, Leaman, Syntax), and also hemodynamic indices of vascular stiffness (including flow-mediated dilation, shear stress, pulse pressure, augmentation index, arterial distensibility), assessment of plaque properties (composition, erosion, rupture), stenosis measures such as fractional flow reserve. Moreover, biomarkers including matrix metalloproteinases, vascular endothelial growth factors and miRNAs, as well as the impact of machine learning support, are described. Special attention is given to age-related aspects and sex-specific characteristics, along with clinical implications. Knowledge gaps are identified and directions for future research formulated.


Assuntos
Aterosclerose , Reserva Fracionada de Fluxo Miocárdico , Placa Aterosclerótica , Feminino , Humanos , Masculino , Caracteres Sexuais , Aterosclerose/diagnóstico , Placa Aterosclerótica/patologia , Tomografia por Emissão de Pósitrons/métodos
17.
Microbiol Resour Announc ; 12(10): e0040523, 2023 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-37750692

RESUMO

We report the complete genome sequences of seven virulent Newcastle disease viruses (NDVs) that were isolated from chickens from live bird markets in the Arusha, Iringa, Mbeya, and Tanga regions of Tanzania in 2012. Phylogenetic analysis revealed that all isolates belong to sub-genotype XIII.1.1.

19.
Atherosclerosis ; 384: 117276, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37775426

RESUMO

Although atherosclerosis is usually considered a disease of the large arteries, risk factors for atherosclerosis also trigger structural and functional abnormalities at a microvascular level. In cardiac disease, microvascular dysfunction is especially relevant in women, among whom the manifestation of ischemic disease due to impaired coronary microcirculation is more common than in men. This sex-specific clinical phenotype has important clinical implications and, given the higher pre-test probability of coronary microvascular dysfunction in females, different diagnostic modalities should be used in women compared to men. In this review, we summarize invasive and non-invasive diagnostic modalities to assess coronary microvascular function, ranging from catheter-based evaluation of endothelial function to Doppler echocardiography and positron emission tomography. Moreover, we discuss different clinical settings in which microvascular disease plays an important role, underlining the importance of choosing the right diagnostic modality depending on the sex of the patients.


Assuntos
Aterosclerose , Doença da Artéria Coronariana , Feminino , Humanos , Masculino , Doença da Artéria Coronariana/diagnóstico por imagem , Microcirculação , Caracteres Sexuais , Circulação Coronária , Vasos Coronários/diagnóstico por imagem
20.
Mov Ecol ; 11(1): 49, 2023 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-37550782

RESUMO

BACKGROUND: Migration is a vital element of the life cycle of many freshwater fish species but is increasingly hampered globally by riverine barriers. Fish passes are a common approach to enable migration past barriers but are often ineffective. More knowledge is required on fish behaviour as they approach barriers such as habitat preferences. METHODS: We evaluate the habitat selection of two upstream migrating fish species, barbel Barbus barbus and grayling Thymallus thymallus, at a hydropower plant in southern Germany, considering individual variation and population trends. Fish were tracked via fine-scale 2D acoustic telemetry in 2018 during their spawning migration. Step selection functions were used to evaluate selection of hydraulic parameters by the fish for a time step of 20 s. Exploratory models were built via model selection for each individual fish, to evaluate the extent of individual variation in model structure. A population model was developed for each species by averaging coefficients from individual models to describe general trends. The extent of individual variation was determined and confidence intervals for the population model coefficients were calculated. RESULTS: Fish varied greatly in individual model structure though common terms were apparent in both species, such as depth, flow velocity, the angular difference between fish and velocity, and the logarithm of the step length. Final population models for barbel included several parameters describing habitat selection and displacement. Barbel selected for faster flows, deeper water, and higher spatial velocity gradients. In addition, they selected to move more with the flow than against. Interactions were also present between habitat parameters, suggesting selection is context dependent. Barbel movement speed also changed with depth, flow velocity and spatial velocity gradient. With grayling, terms often had contrasting effects among individuals and thus general trends could not be distinguished for most terms. CONCLUSION: Our findings demonstrate habitat selection by upstream migrating fish approaching a fish pass and differences in individual selection which may have an impact on barrier management. Step selection functions are a promising approach and can provide useful insight into habitat selection and movement by migrating freshwater fish in an altered river system.

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