Ocean acidification affects species populations and biodiversity through direct negative effects on physiology and behaviour. The indirect effects of elevated CO2 are less well known and can sometimes be counterintuitive. Reproduction lies at the crux of species population replenishment, but we do not know how ocean acidification affects reproduction in the wild. Here, we use natural CO2 vents at a temperate rocky reef and show that even though ocean acidification acts as a direct stressor, it can indirectly increase energy budgets of fish to stimulate reproduction at no cost to physiological homeostasis. Female fish maintained energy levels by compensation: They reduced activity (foraging and aggression) to increase reproduction. In male fish, increased reproductive investment was linked to increased energy intake as mediated by intensified foraging on more abundant prey. Greater biomass of prey at the vents was linked to greater biomass of algae, as mediated by a fertilisation effect of elevated CO2 on primary production. Additionally, the abundance and aggression of paternal carers were elevated at the CO2 vents, which may further boost reproductive success. These positive indirect effects of elevated CO2 were only observed for the species of fish that was generalistic and competitively dominant, but not for 3 species of subordinate and more specialised fishes. Hence, species that capitalise on future resource enrichment can accelerate their reproduction and increase their populations, thereby altering species communities in a future ocean.

Adult survival is arguably the most important demographic parameter for long-lived species as it has a large impact on population growth, and it can be estimated for cetacean populations using natural markings and mark-recapture (MR) modelling. Here we describe a 26-year study of a genetically discrete, resident population of bottlenose dolphins in the Shannon Estuary, Ireland, conducted by an NGO using multiple platforms. We estimated survival rates (SRs) using Cormack-Jolly-Seber models and explored the effects of variable survey effort, multiple researchers, and changes in camera equipment as well as capture heterogeneity induced by changes in marks and site fidelity variation, all common issues affecting longitudinal dolphin studies. The mean adult SR was 0.94 (±0.001 SD) and thus comparable to the estimates reported for other bottlenose dolphin populations. Capture heterogeneity through variation in mark severity was confirmed, with higher capture probabilities for well-marked individuals than for poorly marked individuals and a “transience” effect being detected for less well-marked individuals with 43% only recorded once. Likewise, both SR and capture probabilities were comparatively low for individuals with low site fidelity to the Shannon Estuary, and SR of these individuals additionally decreased even further toward the end of the study, reflecting a terminal bias. This bias was attributed to non-random temporal migration, and, together with high encounter rates in Brandon Bay, supported the hypothesis of range expansion. Our results highlight the importance of consistent and geographically homogenous survey effort and support the differentiation of individuals according to their distinctiveness to avoid biased survival estimates.

Previous studies have investigated the associations between the vaginal microbiome and preterm birth (PTB), with the aim of determining whether differences in community patterns meaningfully alter risk, and could therefore be the target of intervention. We report on vaginal microbial analysis on a subset of the Pregnancy, Infection, and Nutrition (PIN) Study, a prospectively enrolled cohort of women in central North Carolina between 1995-2001. We selected a nested case-control subset of this cohort, including 464 White women (375 term birth and 89 spontaneous PTB, sPTB) and 360 Black women (276 term birth and 84 sPTB). Microbial DNA was extracted from genital track swabs collected mid-pregnancy, and subjected to 16S rRNA taxonomic profiling. We found that microbial community structure is associated with race and sPTB, although the influence of race is stronger than the influence of sPTB. The microbiome of Black women has higher alpha-diversity, higher abundance of Lactobacillus iners and lower abundance of Lactobacillus crispatus. These differences were obscured once maternal douching behavior was considered—specifically, among women who douche, there were no significant differences in microbiome by race. The sPTB associated microbiome exhibited a lower abundance of L. crispatus, while alpha diversity and L. iners were not significantly different. Associations between the microbiome and sPTB were only significant in women who do not douche. While race was a strong predictor of microbial community structure, we also observed strong intercorrelations between a range of maternal factors, including poverty, education, marital status, age, douching and race, with microbiome effect sizes in the range of 1.8-5.2% in univariate models. Therefore, race may simply be a proxy for other socially driven factors that differentiate microbiome community structures. Future work will continue to refine reliable microbial biomarkers for preterm birth across diverse cohorts.