Biology subjects

Martins, E.

Publications and source records attributed to Martins, E..

4 recordsLinked to original sources

bioRxiv2026

Passage through submersible and Archimedes pumps results in decreased migration survival in coho salmon yearlings

Flood-control pumpstations compromise connectivity and survival for migratory fish globally, yet field evaluations of modern "fish-friendly" designs remain scarce. We evaluated out-migration survival and behavior of yearling coho salmon (Oncorhynchus kisutch) entrained through an open-Archimedes screw station (Hammersley) and a conventional radial station (Barrowtown) in the lower Fraser River floodplain, British Columbia. Using acoustic telemetry over two migration seasons (2024-2025), we tracked smolts across an 84-km corridor to New Westminster and modeled apparent survival using a Cormack-Jolly-Seber framework. Baseline natural mortality in downstream controls averaged 60% across years (cumulative survival: ~40%). Entrainment through the conventional radial station caused 87.5% mortality. The open-Archimedes station conferred an improvement over the conventional facility but still induced 11.5% mortality. Notably, pump-induced losses at the Archimedes pump were predominantly latent: while acute survival through immediate tailrace receivers was high (95-98%), survival deficits diverged downstream in the mainstem Fraser River. Entrainment also prolonged out-migration, causing up to a 10-day delay in 2024 driven by forebay holding and depressed downstream transit speeds. Our findings demonstrate that while open-Archimedes screws improve survival relative to legacy radial impellers, they still impose substantial latent mortality. In heavily altered basins where baseline smolt mortality is already high, additive losses from drainage infrastructure may exacerbate survival bottlenecks.

ecology↗

bioRxiv2025

Linking acoustic telemetry data to spatial covariates in river networks with spatially explicit capture-recapture models

O_LISpatially explicit capture-recapture (SECR) models extend classical capture-recapture models to include spatially-explicit animal locations and environmental covariates. SECR models have been widely employed in terrestrial studies to predict the population size and densities of animals assuming a closed population over a defined area. In this work, we extend and apply SECR models to a novel use-case that both uses a relative density formulation and accounts for biased tagging distributions to estimate parameters of habitat use from acoustic telemetry data in a branching river network. C_LIO_LIUsing SECR models, we predict how temperature distributions during the summer feeding season influenced how tagged Arctic grayling (Thymallus arcticus) distributed themselves through the Parsnip watershed in northcentral British Columbia, Canada. We found that the relative density of tagged Arctic grayling peaked at water temperatures of 12.4 {degrees}C. In warm years, relative densities were constricted as parts of the watershed became unfavorably warm. In cool years, fish were distributed widely throughout the watershed. C_LIO_LIIn acoustic telemetry, only the tagged population is available for detection. We highlight several specific considerations and assumptions for using this approach: i.e. (a) activity centres are assumed to remain in the same location throughout the study period, thus the time window of the study should be selected accordingly (e.g., exclude migratory periods); (b) inferences from acoustic telemetry data depict relative (not absolute) densities; and (c) spatial tagging effort must be defined in the model to ensure that predictions are not merely an artefact of tagging effort across space and time. When applied following these assumptions, this method is broadly useful for ecologists as it presents a quantitative way to merge automated telemetry datasets with discrete habitat parameters that drive population distributions through time and are relevant to managers and conservation professionals. Further, this method can be applied to branching river networks in which topological challenges have hindered other statistical approaches. C_LI

ecology↗

bioRxiv2024

Release strategies affect the freshwater residence and survival of hatchery-reared juvenile Chinook Salmon

ObjectiveThis study investigated the effects of size, location and timing of release on the freshwater residence and survival hatchery-reared Chinook Salmon (Oncorhynchus tshawytscha) in the Toquaht River, BC. MethodsJuvenile salmon were PIT tagged and released on three separate dates (May 23, June 9 and 19, 2021) and three distinct locations within the river (lower river [below lake], lake, and upper river [above lake]). Fish were detected near the river mouth using a PIT array, and detection data were analyzed with an integrated model of freshwater residence and capture-recapture using Bayesian inference. ResultThe median duration of freshwater residence was 13.8 days and was longer for fish released in the lake and upper river earlier in the study. The median survival probability was 0.35 and it was higher for fish released in the lake and upper river later in the study. Both freshwater residence time and survival declined with fish size at release. ConclusionThese findings highlight that hatchery release strategies can significantly influence survival and freshwater residence times, underscoring the need for adaptable management practices. Impact statementJuvenile Chinook Salmon survival during freshwater residence and outmigration is strongly influenced by hatchery release strategies, thus optimizing these strategies is key for hatcheries to support the recovery of salmon populations.

ecology↗

bioRxiv2024

Th17 cells require the DNA repair sensor XPC to control oxidative DNA damage

Th17 cells are critical for mucosal immunity, producing IL-17A, IL-17F, and IL-22, but dysregulated Th17 responses are implicated in autoimmune diseases. Despite their susceptibility to oxidative stress in certain conditions, Th17 cells exhibit reduced oxidative DNA damage and cell death compared to other T helper subsets. However, the mechanisms that protect Th17 cells from oxidative stress are poorly understood. Here, we identify Xeroderma Pigmentosum Complementation Group C (XPC) as a key regulator of DNA repair and genomic stability in Th17 cells. In XPC-deficient mice, we demonstrate that the absence of XPC impairs Th17 differentiation, as evidenced by reduced expression of key differentiation markers, including Rorc and Il17a, along with decreased IL-17A production. This deficiency leads to increased oxidative stress, DNA damage, and a metabolic shift from glycolysis to oxidative phosphorylation. Moreover, the transcription factor BATF directly regulates XPC expression, linking the BATF-XPC axis to the maintenance of Th17 cell function. Importantly, we find that restoring antioxidant capacity with N-Acetylcysteine (NAC) rescues IL-17A production and reduces DNA damage in XPC-deficient Th17 cells. Mechanistically, we find that XPC interacts with OGG1, a DNA glycosylase involved in the repair of oxidative DNA damage, highlighting XPCs role in maintaining genomic integrity during Th17 cell differentiation. Our findings reveal a previously unrecognized role for XPC in protecting Th17 cells from oxidative stress, ensuring their proper differentiation and function, with potential implications for targeting DNA repair pathways in autoimmune and inflammatory diseases.

immunology↗