Assessing the Effects of Upwelling-Driven pH and Dissolved Oxygen Variability on Juvenile Rockfishes

Global climate change is expected to increase the frequency and severity of upwelling events in the California Current Ecosystem, yielding concurrent reductions in pH and dissolved oxygen (DO) in coastal marine environments. Juvenile copper (Sebastes caurinus) and gopher (Sebastes carnatus) rockfish may be particularly vulnerable to low pH and DO because they settle nearshore during the upwelling season. Previous studies often use static (i.e., fixed) pH and DO treatments in the laboratory, but ocean chemistry is dynamic and these conditions fluctuate naturally in upwelling zones. To determine how fluctuations in ocean chemistry will impact rockfish behavioral and physiological performance at this critical life history stage, I exposed juveniles of both species to one of the following pH/DO treatments: static control (8.0 pH, 8.3 mg/L DO), static moderate (7.5 pH, 4.0 mg/L DO), static extreme (7.3 pH, 2.0 mg/L DO), and two fluctuating treatments, upwelling and relaxation (recurring cycles of 8 days of 7.3 pH, 2.0 mg/L DO and 8 days of recovery at control conditions). Responses to sublethal stress were evaluated after 1-13 weeks of exposure (or up to six 16-day fluctuating cycles) through behavioral and physiological metrics including lateralization tests, escape time trials, startle response, critical swimming speed (Ucrit), metabolic performance (standard and maximum metabolic rates, capacity for aerobic activity), hypoxia tolerance (critical oxygen tension [Pcrit]), growth rates, body condition, and mortality. I did not observe any significant effects of upwelling conditions on the behavioral metrics of lateralization, escape time, or startle response. Rockfish exhibited impairment in aerobic scope (due to a reduced maximum metabolic rate), swimming speed, and increased ventilation rates and hypoxia tolerance, under simulated upwelling conditions, performing equally to fish in the extreme treatment. In the fluctuating upwelling treatment, both species appeared to recover fully for most physiological metrics when returned to control seawater for 6-7 days (i.e., a simulated oceanographic relaxation event). Both species exhibited the lowest growth rate in the extreme low pH/DO treatment and intermediate growth in the two fluctuating treatments, suggesting lasting cumulative negative impacts of exposure to future upwelling conditions. Mortality was highest in the extreme low treatment and body condition tended to decrease as treatments became more extreme. While juvenile rockfish are susceptible to physiological impairment under extreme climate change scenarios, the severity and duration of future hypoxic, acidic events will ultimately set the consequences for survivorship and physiological fitness, influencing the outcome of the population replenishment process and the long-term sustainability of economically and ecologically important nearshore rockfish species

Spatial and Temporal Variability in Macroalgal Blooms 1 in a Eutrophied Coastal Estuary

All three macroalgal clades (Chlorophyta, Rhodophyta, and Phaeophyceae) contain bloom-forming species. Macroalgal blooms occur worldwide and have negative consequences for coastal habitats and economies. Narragansett Bay (NB), Rhode Island, USA, is a medium sized estuary that is heavily influenced by anthropogenic activities and has been plagued by macroalgal blooms for over a century. Over the past decade, significant investment has upgraded wastewater treatment from secondary treatment to water-quality based limits (i.e. tertiary treatment) in an effort to control coastal eutrophication in this system. The goal of this study was to improve the understanding of multi-year macroalgal bloom dynamics through intensive aerial and ground surveys conducted monthly to bi-monthly during low tides in May-October 2006-2013 in NB. Aerial surveys provided a rapid characterization of macroalgal densities across a large area, while ground surveys provided high resolution measurements of macroalgal identity, percent cover, and biomass. Macroalgal blooms in NB are dominated by Ulva and Gracilaria spp. regardless of year or month, although all three clades of macroalgae were documented. Chlorophyta cover and nutrient concentrations were highest in the middle and upper bay. Rhodophyta cover was highest in the middle and lower bay, while drifting Phaeophyceae cover was patchy. Macroalgal blooms of \u3e1000g fresh mass (gfm)/m2 (max=3510gfm/m2) in the intertidal zone and \u3e3000gfm/m3 (max=8555gfm/m3) in the subtidal zone were observed within a heavily impacted embayment (Greenwich Bay). Macroalgal percent cover (intertidal), biomass (subtidal), and diversity varied significantly between year, month-group, site, and even within sites, with the highest species diversity at sites outside of Greenwich Bay. Total intertidal macroalgal percent cover, as well as subtidal Ulva biomass, were positively correlated with temperature. Dissolved inorganic nitrogen concentrations were correlated with the total biomass of macroalgae and the subtidal biomass of Gracilaria spp. but not the biomass of Ulva spp. Despite seasonal reductions in the nutrient output of wastewater treatment facilities emptying into upper Narragansett Bay in recent years, macroalgal blooms still persist. Continued long-term monitoring of water quality, macroalgal blooms, and ecological indicators is essential to understand the changes in macroalgal bloom dynamics that occur after nutrient reductions from management efforts

Genetic determinants of risk in pulmonary arterial hypertension: international genome-wide association studies and meta-analysis.

BACKGROUND: Rare genetic variants cause pulmonary arterial hypertension, but the contribution of common genetic variation to disease risk and natural history is poorly characterised. We tested for genome-wide association for pulmonary arterial hypertension in large international cohorts and assessed the contribution of associated regions to outcomes. METHODS: We did two separate genome-wide association studies (GWAS) and a meta-analysis of pulmonary arterial hypertension. These GWAS used data from four international case-control studies across 11 744 individuals with European ancestry (including 2085 patients). One GWAS used genotypes from 5895 whole-genome sequences and the other GWAS used genotyping array data from an additional 5849 individuals. Cross-validation of loci reaching genome-wide significance was sought by meta-analysis. Conditional analysis corrected for the most significant variants at each locus was used to resolve signals for multiple associations. We functionally annotated associated variants and tested associations with duration of survival. All-cause mortality was the primary endpoint in survival analyses. FINDINGS: A locus near SOX17 (rs10103692, odds ratio 1·80 [95% CI 1·55-2·08], p=5·13 × 10-15) and a second locus in HLA-DPA1 and HLA-DPB1 (collectively referred to as HLA-DPA1/DPB1 here; rs2856830, 1·56 [1·42-1·71], p=7·65 × 10-20) within the class II MHC region were associated with pulmonary arterial hypertension. The SOX17 locus had two independent signals associated with pulmonary arterial hypertension (rs13266183, 1·36 [1·25-1·48], p=1·69 × 10-12; and rs10103692). Functional and epigenomic data indicate that the risk variants near SOX17 alter gene regulation via an enhancer active in endothelial cells. Pulmonary arterial hypertension risk variants determined haplotype-specific enhancer activity, and CRISPR-mediated inhibition of the enhancer reduced SOX17 expression. The HLA-DPA1/DPB1 rs2856830 genotype was strongly associated with survival. Median survival from diagnosis in patients with pulmonary arterial hypertension with the C/C homozygous genotype was double (13·50 years [95% CI 12·07 to >13·50]) that of those with the T/T genotype (6·97 years [6·02-8·05]), despite similar baseline disease severity. INTERPRETATION: This is the first study to report that common genetic variation at loci in an enhancer near SOX17 and in HLA-DPA1/DPB1 is associated with pulmonary arterial hypertension. Impairment of SOX17 function might be more common in pulmonary arterial hypertension than suggested by rare mutations in SOX17. Further studies are needed to confirm the association between HLA typing or rs2856830 genotyping and survival, and to determine whether HLA typing or rs2856830 genotyping improves risk stratification in clinical practice or trials. FUNDING: UK NIHR, BHF, UK MRC, Dinosaur Trust, NIH/NHLBI, ERS, EMBO, Wellcome Trust, EU, AHA, ACClinPharm, Netherlands CVRI, Dutch Heart Foundation, Dutch Federation of UMC, Netherlands OHRD and RNAS, German DFG, German BMBF, APH Paris, INSERM, Université Paris-Sud, and French ANR