Salt Marsh Hydrogeology: A Review

Groundwater–surface water exchange in salt marsh ecosystems mediates nearshore salt, nutrient, and carbon budgets with implications for biological productivity and global climate. Despite their importance, a synthesis of salt marsh groundwater studies is lacking. In this review, we summarize drivers mediating salt marsh hydrogeology, review field and modeling techniques, and discuss patterns of exchange. New data from a Delaware seepage meter study are reported which highlight small-scale spatial variability in exchange rates. A synthesis of the salt marsh hydrogeology literature reveals a positive relationship between tidal range and submarine groundwater discharge but not porewater exchange, highlighting the multidimensional drivers of marsh hydrogeology. Field studies are heavily biased towards microtidal systems of the US East Coast, with little global information available. A preliminary estimate of marsh porewater exchange along the Mid-Atlantic and South Atlantic Bights is 8–30 × 1013 L y−1, equivalent to recirculating the entire volume of seawater overlying the shelf through tidal marsh sediments in ~30–90 years. This review concludes with a discussion of critical questions to address that will decrease uncertainty in global budget estimates and enhance our capacity to predict future responses to global climate change

Is More, Better? Relationships of Multiple Psychological Well-Being Facets with Cardiometabolic Disease

Objective: Cardiometabolic disease (CMD) is a leading cause of death and disability worldwide. Assessments of psychological well-being taken at one time point are linked to reduced cardiometabolic risk, but psychological well-being may change over time and how longitudinal trajectories of psychological well-being may be related to CMD risk remains unclear. Furthermore, psychological well-being is a multidimensional construct comprised of distinct facets, but no work has examined whether sustaining high levels of multiple facets may confer additive protection. This study tested if trajectories of four psychological well-being facets would be associated with lower risk of self-reported nonfatal CMD. Method: Participants were 4,006 adults aged ≥50 years in the English Longitudinal study of Ageing followed for 18 years at biyearly intervals. Psychological well-being facets were measured in Waves 1–5 using subscales of the Control, Autonomy, Satisfaction, and Pleasure scale. Latent class growth modeling defined trajectories of each facet. Incident CMD cases were self-reported at Waves 6–9. Cox regression models estimated likelihood of incident CMD associated with trajectories of each facet individually and additively (i.e., having persistently high levels on multiple facets over time). Results: After adjusting for relevant covariates, CMD risk was lower for adults with persistently high versus persistently low levels of control and autonomy. When considering potential additive effects, lower CMD risk was also related to experiencing persistently high levels of ≥2 versus 0 psychological well-being facets. Conclusions: Findings suggest having and sustaining multiple facets of psychological well-being is beneficial for cardiometabolic health, and that effects may be additive

Adolescent Psychological Assets and Cardiometabolic Health Maintenance in Adulthood: Implications for Health Equity

Background Positive cardiometabolic health (CMH) is defined as meeting recommended levels of multiple cardiometabolic risk factors in the absence of manifest disease. Prior work finds that few individuals—particularly members of minoritized racial and ethnic groups—meet these criteria. This study investigated whether psychological assets help adolescents sustain CMH in adulthood and explored interactions by race and ethnicity. Methods and Results Participants were 3478 individuals in the National Longitudinal Study of Adolescent Health (49% female; 67% White, 15% Black, 11% Latinx, 6% other [Native American, Asian, or not specified]). In Wave 1 (1994–1995; mean age=16 years), data on 5 psychological assets (optimism, happiness, self‐esteem, belongingness, and feeling loved) were used to create a composite asset index (range=0–5). In Waves 4 (2008; mean age=28 years) and 5 (2016–2018; mean age=38 years), CMH was defined using 7 clinically assessed biomarkers. Participants with healthy levels of ≥6 biomarkers at Waves 4 and 5 were classified as maintaining CMH over time. The prevalence of CMH maintenance was 12%. Having more psychological assets was associated with better health in adulthood (odds ratio [OR]linear trend, 1.12 [95% CI, 1.01–1.25]). Subgroup analyses found substantive associations only among Black participants (OR, 1.35 [95% CI, 1.00–1.82]). Additionally, there was some evidence that racial and ethnic disparities in CMH maintenance may be less pronounced among participants with more assets. Conclusions Youth with more psychological assets were more likely to experience favorable CMH patterns 2 decades later. The strongest associations were observed among Black individuals. Fostering psychological assets in adolescence may help prevent cardiovascular disease and play an underappreciated role in shaping health inequities

The Social Determinants of Ideal Cardiovascular Health: A Global Systematic Review

This systematic review synthesizes research published from January 2010-July 2022 on the social determinants of ideal cardiovascular health (CVH) carried out around the world and compares trends in high-income countries (HICs) to those in low- and middle-income countries (LMICs). 41 studies met inclusion criteria (n = 28 HICs, n = 13 LMICs). Most were from the United States (n = 22) and cross-sectional (n = 33), and nearly all evaluated associations among adults. Among studies conducted in LMICs, nearly all were from middle-income countries and only one was carried out in low-income country. Education (n = 24) and income/wealth (n = 17) were the most frequently examined social determinants in both HICs and LMICs. Although most studies assessed ideal CVH using reliable and valid methods (n = 24), only 7 used criteria pre-defined by the American Heart Association to characterize ideal levels of each CVH metric. Despite heterogeneity in how outcome measures were derived and analyzed, consistent associations were evident between multiple markers of higher social status (i.e. greater education, income/wealth, socioeconomic status, racial/ethnic majority status) and greater levels of ideal CVH across both country contexts. Gaps in the literature include evidence from LMICs and HICs other than the United States, longitudinal research, and investigations of a wider array of social determinants beyond education and income/wealth

The renaissance of Odum\u27s outwelling hypothesis in \u27blue carbon\u27 science

The term ‘Blue Carbon’ was coined about a decade ago to highlight the important carbon sequestration capacity of coastal vegetated ecosystems. The term has paved the way for the development of programs and policies that preserve and restore these threatened coastal ecosystems for climate change mitigation. Blue carbon research has focused on quantifying carbon stocks and burial rates in sediments or accumulating as biomass. This focus on habitat-bound carbon led us to losing sight of the mobile blue carbon fraction. Oceans, the largest active reservoir of carbon, have become somewhat of a blind spot. Multiple recent investigations have revealed high outwelling (i.e., lateral fluxes or horizontal exports) of dissolved inorganic (DIC) and organic (DOC) carbon, as well as particulate organic carbon (POC) from blue carbon habitats. In this paper, we conceptualize outwelling in mangrove, saltmarsh, seagrass and macroalgae ecosystems, diagnose key challenges preventing robust quantification, and pave the way for future work integrating mobile carbon in the blue carbon framework. Outwelling in mangroves and saltmarshes is usually dominated by DIC (mostly as bicarbonate), while POC seems to be the major carbon species exported from seagrass meadows and macroalgae forests. Carbon outwelling science is still in its infancy, and estimates remain limited spatially and temporally. Nevertheless, the existing datasets imply that carbon outwelling followed by ocean storage is relevant and may exceed local sediment burial as a long-term ( \u3e centuries) blue carbon sequestration mechanism. If this proves correct as more data emerge, ignoring carbon outwelling may underestimate the perceived sequestration capacity of blue carbon ecosystems

The renaissance of Odum's outwelling hypothesis in 'Blue Carbon' science

The term ‘Blue Carbon’ was coined about a decade ago to highlight the important carbon sequestration capacity of coastal vegetated ecosystems. The term has paved the way for the development of programs and policies that preserve and restore these threatened coastal ecosystems for climate change mitigation. Blue carbon research has focused on quantifying carbon stocks and burial rates in sediments or accumulating as biomass. This focus on habitat-bound carbon led us to losing sight of the mobile blue carbon fraction. Oceans, the largest active reservoir of carbon, have become somewhat of a blind spot. Multiple recent investigations have revealed high outwelling (i.e., lateral fluxes or horizontal exports) of dissolved inorganic (DIC) and organic (DOC) carbon, as well as particulate organic carbon (POC) from blue carbon habitats. In this paper, we conceptualize outwelling in mangrove, saltmarsh, seagrass and macroalgae ecosystems, diagnose key challenges preventing robust quantification, and pave the way for future work integrating mobile carbon in the blue carbon framework. Outwelling in mangroves and saltmarshes is usually dominated by DIC (mostly as bicarbonate), while POC seems to be the major carbon species exported from seagrass meadows and macroalgae forests. Carbon outwelling science is still in its infancy, and estimates remain limited spatially and temporally. Nevertheless, the existing datasets imply that carbon outwelling followed by ocean storage is relevant and may exceed local sediment burial as a long-term (>centuries) blue carbon sequestration mechanism. If this proves correct as more data emerge, ignoring carbon outwelling may underestimate the perceived sequestration capacity of blue carbon ecosystems.publishedVersio

A large scale hearing loss screen reveals an extensive unexplored genetic landscape for auditory dysfunction

The developmental and physiological complexity of the auditory system is likely reflected in the underlying set of genes involved in auditory function. In humans, over 150 non-syndromic loci have been identified, and there are more than 400 human genetic syndromes with a hearing loss component. Over 100 non-syndromic hearing loss genes have been identified in mouse and human, but we remain ignorant of the full extent of the genetic landscape involved in auditory dysfunction. As part of the International Mouse Phenotyping Consortium, we undertook a hearing loss screen in a cohort of 3006 mouse knockout strains. In total, we identify 67 candidate hearing loss genes. We detect known hearing loss genes, but the vast majority, 52, of the candidate genes were novel. Our analysis reveals a large and unexplored genetic landscape involved with auditory function

Salt Marsh Hydrogeology: A Review

Groundwater–surface water exchange in salt marsh ecosystems mediates nearshore salt, nutrient, and carbon budgets with implications for biological productivity and global climate. Despite their importance, a synthesis of salt marsh groundwater studies is lacking. In this review, we summarize drivers mediating salt marsh hydrogeology, review field and modeling techniques, and discuss patterns of exchange. New data from a Delaware seepage meter study are reported which highlight small-scale spatial variability in exchange rates. A synthesis of the salt marsh hydrogeology literature reveals a positive relationship between tidal range and submarine groundwater discharge but not porewater exchange, highlighting the multidimensional drivers of marsh hydrogeology. Field studies are heavily biased towards microtidal systems of the US East Coast, with little global information available. A preliminary estimate of marsh porewater exchange along the Mid-Atlantic and South Atlantic Bights is 8–30 × 1013 L y−1, equivalent to recirculating the entire volume of seawater overlying the shelf through tidal marsh sediments in ~30–90 years. This review concludes with a discussion of critical questions to address that will decrease uncertainty in global budget estimates and enhance our capacity to predict future responses to global climate change

Distinct Chemical Microenvironments Drive Two Different Macrofaunal Habitat Types in the East Pacific Rise, 9°50 N Hydrothermal Ecosystems

Volcanic eruptions around biomass-rich hydrothermal habitats can lead to the rapid burial of organic carbon, which can later fuel subseafloor life. Yet, still little is known on the habitat evolution within a vent volcanic cycle. The vents at East Pacific Rise (EPR), 9°50 N hosted a full cycle of macrofaunal succession between two eruptions that occurred in 1991 and 2005. In April 2017, 12 years from the latest eruption, and as a follow-up of our work in the last decade, we conducted research at the site with the submersibleAlvin. Coupling video-based observations to an in-situ voltammetric sensor probing and ex-situ analyses of habitat fluids, we demonstrate two major habitat types: The first are the relatively mild-temperature habitats where oxygen and sulfide coexist and fuel invertebrate chemosymbiosis. ParticularlyRiftiatubeworms have been extensively observed around Tica and Biovent sites, however the temperatures and sulfide concentrations around these invertebrates were lower than the earlier phase of the volcanic cycle. Mussels started to invade tubeworm habitats, confirming the cooling pattern. In contrast, away from the classic tubeworm habitats the second habitat type emerges. These are mostly in the form of diffuse flow sources, excluding tubeworms and mussel assemblages, only inhabited by high-T tolerant species such as sulfur- oxidizing microbial mats andAlvinella pompejana. These types of habitats cluster around the Q and M vent area, where metal-rich suboxic processes dominate. At the same temperature, this second habitat type contains more electron donors such as dissolved metals that consume any oxygen, leading to suboxic conditions and lower temperature-sulfide slopes. Twelve years after the 2005/2006 eruptions, mussels are taking over as predicted only in the areas where chemical dynamics allows coexistence of oxygen and sulfide. The mats in the Q/M area do not conform to such a succession scheme, indicating that those assemblages remain more 'resilient' towards replacement by competitors due primarily to their distinct fluid chemistry

Sea-level rise and warming mediate coastal groundwater discharge in the Arctic

Groundwater discharge is an important mechanism through which fresh water and associated solutes are delivered to the ocean. Permafrost environments have traditionally been considered hydrogeologically inactive, yet with accelerated climate change and permafrost thaw, groundwater flow paths are activating and opening subsurface connections to the coastal zone. While warming has the potential to increase land-sea connectivity, sea-level change has the potential to alter land-sea hydraulic gradients and enhance coastal permafrost thaw, resulting in a complex interplay that will govern future groundwater discharge dynamics along Arctic coastlines. Here, we use a recently developed permafrost hydrological model that simulates variable-density groundwater flow and salinity-dependent freeze-thaw to investigate the impacts of sea-level change and land and ocean warming on the magnitude, spatial distribution, and salinity of coastal groundwater discharge. Results project both an increase and decrease in discharge with climate change depending on the rate of warming and sea-level change. Under high warming and low sea-level rise scenarios, results show up to a 58% increase in coastal groundwater discharge by 2100 due to the formation of a supra-permafrost aquifer that enhances freshwater delivery to the coastal zone. With higher rates of sea-level rise, the increase in discharge due to warming is reduced to 21% as sea-level rise decreased land-sea hydraulic gradients. Under lower warming scenarios for which supra-permafrost groundwater flow was not established, discharge decreased by up to 26% between 1980 and 2100 for high sea-level rise scenarios and increased only 8% under low sea-level rise scenarios. Thus, regions with higher warming rates and lower rates of sea-level change (e.g. northern Nunavut, Canada) will experience a greater increase in discharge than regions with lower warming rates and higher rates of sea-level change. The magnitude, location and salinity of discharge have important implications for ecosystem function, water quality, and carbon dynamics in coastal zones