Macroalgal Monitoring in the Great Bay Estuary: 2018 Annual Report

Since 2013, the abundance and taxa of intertidal macroalgae have been assessed at fixed locations throughout the Great Bay Estuary in New Hampshire. Algal abundance may be influenced by environmental conditions such as nutrient levels, water temperature, light and invasive species. Therefore, abundance of different algal groups can provide insights into the overall health of the estuary and signal ecological change. In 2018, intertidal abundance data for percentage cover and biomass were collected, as planned, from five of the eight sites. For the first time, subtidal sampling arrays were also incorporated at all four sites in Great Bay proper to monitor macroalgae at lower elevations and to collect data on eelgrass communities coexisting with the algae

Short-Term Effects of Thin-Layer Sand Placement on Salt Marsh Grasses: A Marsh Organ Field Experiment

Salt marshes can build in elevation with sea-level rise through accumulation of inorganic sediment and organic matter, but marshes worldwide are under threat of drowning due to rapid rates of sea-level rise that outpace natural marsh building rates. The application of a thin layer of sediment to the marsh surface (thin-layer placement [TLP]) is a tool to build elevation and decrease flooding stress, but its effects on marsh plants are understudied, especially in New England. In a novel application of a marsh organ experiment (i.e. rows of pots at different elevations), the addition of 10 cm of sand to pots planted with Spartina alterniflora and Spartina patens resulted in fewer stems than controls for S. patens but not S. alterniflora after 2 months. However, total biomass and root mass were not significantly impacted for either species, suggesting plants will fully recover from TLP over longer timescales. Effects of TLP on biomass and stem density did not vary significantly by elevation. Although long-term research is still needed, short-term equivalency in biomass between TLP treatments and controls suggests TLP of 10 cm is a promising strategy to enhance the ability of marshes to build vertically as sea level rises in New England

Regulation of plasmid-encoded isoprene metabolism in Rhodococcus, a representative of an important link in the global isoprene cycle

Emissions of biogenic volatile organic compounds (VOCs) form an important part of the global carbon cycle, comprising a significant proportion of net ecosystem productivity. They impact atmospheric chemistry and contribute directly and indirectly to greenhouse gases. Isoprene, emitted largely from plants, comprises one third of total VOCs, yet in contrast to methane, which is released in similar quantities, we know little of its biodegradation. Here, we report the genome of an isoprene degrading isolate, Rhodococcus sp. AD45, and, using mutagenesis shows that a plasmid-encoded soluble di-iron centre isoprene monooxygenase (IsoMO) is essential for isoprene metabolism. Using RNA sequencing (RNAseq) to analyse cells exposed to isoprene or epoxyisoprene in a substrate-switch time-course experiment, we show that transcripts from 22 contiguous genes, including those encoding IsoMO, were highly upregulated, becoming among the most abundant in the cell and comprising over 25% of the entire transcriptome. Analysis of gene transcription in the wild type and an IsoMO-disrupted mutant strain showed that epoxyisoprene, or a subsequent product of isoprene metabolism, rather than isoprene itself, was the inducing molecule. We provide a foundation of molecular data for future research on the environmental biological consumption of this important, climate-active compound

Seaweed Monitoring in the Great Bay Estuary, NH: 2020 Annual Report

As water temperatures rise due to global warming and nitrogen inputs change, it is important to understand how these changes are impacting vegetative communities that form the basic habitat structure in the Great Bay Estuary, NH. The abundance and taxa of intertidal seaweeds have been monitored at fixed locations throughout the Estuary since 2013. In 2020, percent cover and biomass were collected from five intertidal and four subtidal sampling locations. Data from 2013-2020 show appreciable amounts of nuisance seaweeds (primarily reds), including several introduced species. Cover of green seaweeds decreased significantly over time at the two intertidal sites (Depot Road and Adams Point), and red seaweed decreased at one site (Depot Road). However, results from 2020 still show high levels of nuisance red seaweed, particularly at the lowest intertidal elevations. At subtidal locations, cover of both eelgrass and algae was higher in 2020 than in 2019

Seaweed Monitoring in the Great Bay Estuary: 2019 Annual Report

As global warming increases temperature and nitrogen inputs change—either due to greater inputs associated with growing populations in the Great Bay or with nitrogen reductions at wastewater treatment plants—it is important to understand how these changes are impacting the estuary. To that end, the abundance and taxa of intertidal seaweeds have been assessed at fixed locations throughout the estuary since 2013. Seaweed abundance may be influenced by environmental conditions such as nutrient levels, water temperature, light availability, and invasive species. Therefore, seaweed communities can provide insights into the overall health of the estuary and signal ecological change. In 2019, abundance data (percent cover and biomass) were collected from five of the eight intertidal sampling locations and four subtidal locations. Two more sampling arrays were established at each subtidal site, making three replicates per site. Data from 2013-2019 show appreciable cover and biomass of nuisance seaweeds (reds and greens), including several introduced species. Green seaweeds decreased in cover at the two intertidal sites that are sampled annually (Depot Road and Adams Point), and cover of red seaweed decreased at one site (Depot Road). However, there were no decreases at the other six sites, and results from 2019 still show high levels of nuisance seaweed at the lowest intertidal elevations. In subtidal areas, percent cover assessments by snorkel appeared successful based on strong correlations between cover and biomass. Percent cover of seagrass measured by snorkel was very similar to independent measurements from underwater photos. The abundance of seaweed in association with eelgrass beds was ecologically significant and may have impacted eelgrass density and productivity. Further monitoring of seaweed and eelgrass is required to determine potential impacts to the estuary from emerging threats of increased nutrients from impervious surfaces and rising water temperatures due to global warming, as well as reduced nutrient threats from improvements to wastewater treatment plants and stormwater management. For example, the 2019 eelgrass survey showed an increase in area of eelgrass beds within Great and Little Bays which co-occurred with declines in nuisance seaweed at two of our stations in Great Bay

Closing the Nuclear Fuel Cycle with a Simplified Minor Actinide Lanthanide Separation Process (ALSEP) and Additive Manufacturing

Expanded low-carbon baseload power production through the use of nuclear fission can be enabled by recycling long-lived actinide isotopes within the nuclear fuel cycle. This approach provides the benefits of (a) more completely utilizing the energy potential of mined uranium, (b) reducing the footprint of nuclear geological repositories, and (c) reducing the time required for the radiotoxicity of the disposed waste to decrease to the level of uranium ore from one hundred thousand years to a few hundred years. A key step in achieving this goal is the separation of long-lived isotopes of americium (Am) and curium (Cm) for recycle into fast reactors. To achieve this goal, a novel process was successfully demonstrated on a laboratory scale using a bank of 1.25-cm centrifugal contactors, fabricated by additive manufacturing, and a simulant containing the major fission product elements. Americium and Cm were separated from the lanthanides with over 99.9% completion. The sum of the impurities of the Am/Cm product stream using the simulated raffinate was found to be 3.2 × 10−3 g/L. The process performance was validated using a genuine high burnup used nuclear fuel raffinate in a batch regime. Separation factors of nearly 100 for 154Eu over 241Am were achieved. All these results indicate the process scalability to an engineering scale

Effects of a large-scale, natural sediment deposition event on plant cover in a Massachusetts salt marsh

In mid-winter 2018, an unprecedented sediment deposition event occurred throughout portions of the Great Marsh in Massachusetts. Evaluation of this event in distinct marsh areas spanning three towns (Essex, Ipswich, and Newbury) revealed deposition covering 29.2 hectares with an average thickness of 30.1±2.1 mm measured shortly after deposition. While sediment deposition helps marshes survive sea level rise by building elevation, effects of such a large-scale deposition on New England marshes are unknown. This natural event provided an opportunity to study effects of large-scale sediment addition on plant cover and soil chemistry, with implications for marsh resilience. Sediment thickness did not differ significantly between winter and summer, indicating sediment is not eroding or compacting. The deposited sediment at each site had similar characteristics to that of the adjacent mudflat (e.g., texture, bivalve shells), suggesting that deposited materials resulted from ice rafting from adjacent flats, a natural phenomenon noted by other authors. Vegetative cover was significantly lower in plots with rafted sediment (75.6±2.3%) than sediment-free controls (93.1±1.6%) after one growing season. When sorted by sediment thickness categories, the low thickness level (1–19 mm) had significantly greater percent cover than medium (20–39 mm) and high (40–90 mm) categories. Given that sediment accretion in the Great Marsh was found to average 2.7 mm per year, the sediment thickness documented herein represents ~11 years of sediment accretion with only a 25% reduction in plant cover, suggesting this natural sediment event will likely increase long-term marsh resilience to sea level rise

Contact with Caregivers is Associated with Composition of the Infant Gastrointestinal Microbiome in the First 6 Months of Life

Objectives Little is known about how physical contact at birth and early caregiving environments influence the colonization of the infant gastrointestinal microbiome. We investigated how infant contact with caregivers at birth and within the first 2 weeks of life relates to the composition of the gastrointestinal microbiome in a sample of U.S. infants (n = 60). Methods Skin-to-skin and physical contact with caregivers at birth and early caregiving environments were surveyed at 2 weeks postpartum. Stool samples were collected from infants at 2 weeks, 2, 6, and 12 months of age and underwent 16S rRNA sequencing as a proxy for the gastrointestinal microbiome. Associations between early caregiving environments and alpha and beta diversity, and differential abundance of bacteria at the genus level were assessed using PERMANOVA, and negative binomial mixed models in DEseq2. Results Time in physical contact with caregivers explained 10% of variation in beta diversity at 2 weeks\u27 age. The number of caregivers in the first few weeks of life explained 9% of variation in beta diversity at 2 weeks and the number of individuals in physical contact at birth explained 11% of variation in beta diversity at 6 months. Skin-to-skin contact on the day of birth was positively associated with the abundance of eight genera. Infants held for by more individuals had greater abundance of eight genera. Discussion Results reveal a potential mechanism (skin-to-skin and physical contact) by which caregivers influence the infant gastrointestinal microbiome. Our findings contribute to work exploring the social transmission of microbes

Surface temperature and spectral measurements at Santiaguito lava dome, Guatemala

An infrared thermometer, spectroradiometer and digital video camera were used to observe and document short-term evolution of surface brightness temperature and morphology at Santiaguito lava dome, Guatemala. The thermometer dataset shows 40–70 minute-long cooling cycles, each defined by a cooling curve that is both initiated and terminated by rapid increases in temperature due to regular ash venting. The average cooling rate calculated for each cycle range from 0.9 to 1.6°C/min. We applied a two-component thermal mixture model to the spectroradiometer (0.4–2.5 μm) dataset. The results suggest that the observed surface morphology changed from a cool (120–250°C) crust-dominated surface with high temperature fractures (\u3e900°C) in the first segment of the measurement period to an isothermal surface at moderately high temperature (350–500°C) during the second segment. We attribute the change in the thermal state of the surface to the physical rearrangement of the dome\u27s surface during the most energetic of the ash eruptions