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Optimal egg size theory implies that female organisms balance between fecundity and individual offspring investment according to their environment. Past interspecific studies suggest that fishes in large marine systems generally produce smaller eggs than those in small freshwater systems. We tested whether intraspecific egg size variation reflected a similar pattern by comparing egg size among yellow perch ( Perca flavescens ) populations inhabiting a range of system sizes. In 2018, 2019, and 2023, we collected yellow perch egg samples from 12 locations in systems ranging in surface area from 37 to 5,390,492 ha. First, we found that egg diameter significantly increased with maternal total length in five of eight individually tested populations. After accounting for these maternal effects, we found a significant interaction, where females inhabiting larger lakes, such as the main basins of Lakes Erie and Michigan, produced smaller eggs than those in smaller inland lakes, and the greatest differences were demonstrated among females of greater total length. This egg size variation in the largest females is consistent with interspecific egg size comparisons between marine and freshwater fishes. However, by examining a single species across vastly different environments, we were able to support theoretical expectations that maternal investment in offspring should vary with environmental conditions controlling early-life resource acquisition and competition., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

Body size and growth rate can influence individual and population success by mediating fitness. Understanding the factors that influence growth can be difficult to disentangle, however, because growth can be shaped by environmental conditions recently experienced, as well as legacy effects from conditions experienced earlier in life and by parents (via parental effects). To improve understanding of growth among annual cohorts (1982-2015) of Lake Erie Walleye (Sander vitreus), a species with life-history and growth characteristics similar to many other long-lived, iteroparous fishes, we determined the role of the following hypothesised factors: (H1) recent environmental conditions; (H2) traits and experiences of the cohort, including growth, in the previous year; (H3) early-life cohort density; (H4) early-life body size; and (H5) parental composition and environment. We evaluated the relative importance of these hypothesised factors using piecewise structural equation modelling in an information-theoretic framework. Our results indicated that cohort-specific growth of Lake Erie Walleye was most strongly influenced by traits (growth) and experiences of the cohort during the previous year (H2) and parental composition and environment (H5). The observed negative relationship with growth during the previous year may indicate that Walleye exhibit compensatory growth. The relationships with parental sizes and environments may mean that parental contributions to offspring affects cohorts into adulthood, with serious implications for the effects of climate change. Warm winters appear to negatively influence offspring growth performance for many years. Legacy effects had a stronger influence on cohort growth than recent environmental conditions, providing new understanding of how somatic growth is regulated in Lake Erie's Walleye population. Specifically, the parental composition and environment appear important via epigenetic and/or egg-provisioning legacies, with carryover effects modifying growth among years. Ultimately, our findings demonstrate that understanding recent growth in animal populations similar to Lake Erie Walleye may require knowledge of past conditions, including those experienced by parents., (© 2024 The Author(s). Journal of Animal Ecology © 2024 British Ecological Society.)

Marine heatwaves (MHWs) are often associated with physiological changes throughout biological communities but can also result in biomass declines that correspond with shifts in phenology. We examined the response of larval Pacific cod (Gadus macrocephalus) to MHWs in the Gulf of Alaska across seven years to evaluate the effects of MHWs on hatch phenology, size-at-age, and daily growth and identify potential regulatory mechanisms. Hatch dates were, on average, 19 days earlier since the onset of MHWs, shifting a mean of 15 days earlier per 1 ℃ increase. Size-at-capture was larger during & between MHWs but, contrary to expectations, larvae grew slower and were smaller in size-at-age. The larger size during & between MHWs can be entirely explained by older ages due to earlier hatching. Daily growth variation was well-explained by an interaction among age, temperature, and hatch date. Under cool conditions, early growth was fastest for the latest hatchers. However, this variation converged at warmer temperatures, due to faster growth of earlier hatchers. Stage-specific growth did not vary with temperature, remaining relatively similar from 4 to 8 ℃. Temperature-related demographic changes were more predictable based on phenological shifts rather than changes in growth, which could affect population productivity after MHWs., (© 2024. The Author(s).)

Marine Heatwaves (MHWs) can directly influence survival of marine fishes, particularly for early life stages, including age-0 juveniles during their residence in coastal nursery habitats. However, the ability of nurseries to support high fish densities, optimize foraging and growth, and protect against predators may be altered during MHWs. Gulf of Alaska Pacific cod (Gadus macrocephalus) larval, juvenile, and adult abundances declined dramatically following MHW events in 2014-2016 and 2019. To evaluate coastal nursery function during MHWs, we compared diet composition, recent growth, size, condition, and abundance of age-0 juveniles throughout their first summer before, during, and between MHWs. Diet shifted to larger prey during MHWs, particularly mysids, but diet did not appear to influence growth. We observed faster growth rates during MHWs, yet even when accounting for growth, we could not explain the higher body sizes observed in August during MHWs. Together with lower abundance and the near absence of small fish in the nursery by August during MHWs, these patterns highlight potential for size-selection and a reduced ability of nursery habitats to buffer against environmental variability during MHWs, with only a small number of large "super survivors" persisting through the summer., (© 2024. The Author(s).)

While severe hypoxia can be lethal and is usually avoided by mobile aquatic organisms, moderate hypoxic conditions are likely more prevalent and may affect organisms, such as fishes, in a variety of systems. However, fishes have the potential to adjust physiologically and behaviorally and thus reduce the negative effects of hypoxia. Quantifying such physiological responses may shed light on the ability of fishes to tolerate reduced oxygen concentrations. This study assessed how two different hatchery populations of yellow perch Perca flavescens, a fish that is likely to encounter moderate hypoxic conditions in a variety of systems, responded to moderate hypoxic exposure through three experiments: 1) a behavioral foraging experiment, 2) an acute exposure experiment, and 3) a chronic exposure experiment. No marked behavioral or physiological adjustments were observed in response to hypoxia (e.g., hemoglobin, feeding rate, movement frequency, gene expression did not change to a significant degree), possibly indicating a high tolerance level in this species. This may allow yellow perch to utilize areas of moderate hypoxia to continue foraging while avoiding predators that may be more sensitive to moderately low oxygen., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Women infected with human papillomavirus (HPV) are at a higher risk of developing cervical lesions. In the current study, self and clinician-collected vaginal and cervical samples from women were processed to detect HPV DNA using polymerase chain reaction (PCR) with PGMY09/11 primers. HPV genotypes were determined using type-specific PCR. HPV DNA detection showed good concordance between self and clinician-collected samples (84.6%; kappa = 0.72). HPV infection was found in 30% women and genotyping was more concordant among high-risk HPV (HR-HPV) than low-risk HPV (HR-HPV). HPV16 was the most frequently detected among the HR-HPV types. LR-HPV was detected at a higher frequency in self-collected; however, HR-HPV types were more frequently identified in clinician-collected samples than in self-collected samples. HPV infections of multiple types were detected in 20.5% of clinician-collected samples and 15.5% of self-collected samples. In this study, we demonstrated that the HPV DNA detection rate in self-collected samples has good agreement with that of clinician-collected samples. Self-collected sampling, as a primary prevention strategy in countries with few resources, could be effective for identifying cases of HR-HPV, being more acceptable. The use of this method would enhance the coverage of screening programs for cervical cancer.