Chasing Nutrients and Algal Blooms in Gulf and Caribbean Waters: A Personal Story

Over the past 5 decades, coastal waters have experienced unprecedented global change, including widespread eutrophication, harmful algal blooms (HAB), dead zones, and loss of biodiversity. During this period, I have studied the effects of nutrients (N, P) on HAB dynamics in tropical seagrass and coral reef ecosystems. Important findings that emerged from my research include: 1) a primary role of anthropogenic nitrogen (N) relative to phosphorus (P) as a driving factor in algal blooms and coastal eutrophication; 2) altered N:P stoichiometry that results in greater P—limitation and metabolic stress in reef corals; 3) recognition that macroalgal blooms be considered as a type of HAB because of their increasingly negative impacts on oceans and human health; and 4) mitigation of anthropogenic N inputs can increase resiliency of seagrass and coral reef ecosystems relative to population growth and climate change. Major developments during the research involved the use of computers and software; EAN NITROX, dive computers, and high resolution underwater video to make SCUBA surveys safer and more effective; analysis of stable nitrogen isotopes, sucralose, and other human tracers to discriminate between natural and anthropogenic N sources; and satellite remote sensing to better monitor the large—scale HAB phenomena. My research sparked considerable debate about the root cause(s) of algal blooms on Caribbean coral reefs, as several senior coral reef biologists had concluded this problem was caused solely by the reduction of reef grazers. Since 2011, the massive Sargassum influx to the Caribbean region appears to be a eutrophication response to increasing nutrients in the tropical Atlantic Ocean and is now considered the largest HAB on the planet. Going forward, early career scientists need to extend research on declining coastal ecosystem health to upland watersheds to better understand and mitigate nutrient pollution at its source(s) to enhance resilience of seagrass and coral reef ecosystems to climate change

Towards Designing an Integrated Architecture for NEO Characterization, Mitigation, Scientific Evaluation, and Resource Utilization

This poster reviews the planning and design for an integrated architecture for characterization, mitigation, scientific evaluation and resource utilization of near earth objects. This includes tracks to observe and characterize the nature of the threat posed by a NEO, and deflect if a significant threat is posed. The observation stack can also be used for a more complete scientific analysis of the NEO

Synthesis of Aryl Ketoamides via Aryne Insertion into Imides

An insertion of arenes into both imides and anhydrides via reactive aryne intermediates is presented. The reaction is performed under exceptionally mild conditions, and the corresponding ketoamide products are amenable to derivatization to deliver a variety of synthetically useful motifs such as quinolones, indoles, and ketoanilines

Nutrient content and stoichiometry of pelagic Sargassum reflects increasing nitrogen availability in the Atlantic Basin

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Lapointe, B. E., Brewton, R. A., Herren, L. W., Wang, M., Hu, C., McGillicuddy, D. J., Lindell, S., Hernandez, F. J., & Morton, P. L. Nutrient content and stoichiometry of pelagic Sargassum reflects increasing nitrogen availability in the Atlantic Basin. Nature Communications, 12(1), (2021): 3060, https://doi.org/10.1038/s41467-021-23135-7.The pelagic brown macroalgae Sargassum spp. have grown for centuries in oligotrophic waters of the North Atlantic Ocean supported by natural nutrient sources, such as excretions from associated fishes and invertebrates, upwelling, and N2 fixation. Using a unique historical baseline, we show that since the 1980s the tissue %N of Sargassum spp. has increased by 35%, while %P has decreased by 44%, resulting in a 111% increase in the N:P ratio (13:1 to 28:1) and increased P limitation. The highest %N and δ15N values occurred in coastal waters influenced by N-rich terrestrial runoff, while lower C:N and C:P ratios occurred in winter and spring during peak river discharges. These findings suggest that increased N availability is supporting blooms of Sargassum and turning a critical nursery habitat into harmful algal blooms with catastrophic impacts on coastal ecosystems, economies, and human health.This work was funded by the US NASA Ocean Biology and Biogeochemistry Program (80NSSC20M0264, NNX16AR74G) and Ecological Forecast Program (NNX17AF57G), NOAA RESTORE Science Program (NA17NOS4510099), National Science Foundation (NSF-OCE 85–15492 and OCE 88–12055), “Save Our Seas” Specialty License Plate funds, granted through the Harbor Branch Oceanographic Institute Foundation, Ft. Pierce, FL, and a Red Wright Fellowship from the Bermuda Biological Station. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR-1644779 and the State of Florida. D.J.M. gratefully acknowledges the Holger W. Jannasch and Columbus O’Donnell Iselin Shared Chairs for Excellence in Oceanography, as well as support from the Mill Reef Fund

Gene profiling of cell cycle progression through S-phase reveals sequential expression of genes required for DNA replication and nucleosome assembly

The ordered expression of genes after growth factor stimulation in G(1) supportsthe onset of DNA replication. To characterize regulatory events during S-phase when cell cycle progression has become growth factor independent, we have profiled the expression of over 7,000 human genes using GeneChip DNA microarray analysis. HeLa cells were synchronized at the beginning of S-phase by thymidine/aphidicolin block, and RNA populations were analyzed throughout the S and G(2) phases. Expression of genes involved in DNA replication is maximal during early S-phase, whereas histone mRNAs peak at mid S-phase. Genes related to cell proliferation, including those encoding cyclins, oncoproteins, growth factors, proteins involved in signal transduction, and DNA repair proteins, follow distinct temporal patterns of expression that are functionally linked to initiation of DNA replication and progression through S-phase. The timing of expression for many genes in tumor-derived HeLa cells is highly conserved when compared with normal cells. In contrast, a number of genes show growth phenotype-related expression patterns that may directly reflect loss of stringent growth control in tumor cells. Our data reveal there is a core subset of cell growth-related genes that is fundamental to cycling cells irrespective of cell growth phenotype

Managing understory light conditions in boreal mixedwoods through variation in the intensity and spatial pattern of harvest: A modelling approach

In the context of partial harvesting, adequately managing post-harvest light conditions are essential to obtain a desired composition of tree species regeneration. The objective of this study was to determine how varying the intensity and spatial pattern of harvest would affect understory light conditions in boreal mixedwood stands of northwestern Quebec using the spatially explicit SORTIE-ND light model. The model was evaluated based on comparisons of observed and predicted light levels in both mapped and un-mapped plots. In mapped plots, reasonably accurate predictions of the overall variation in light levels were obtained, but predictions tended to lack spatial precision. In un-mapped plots, SORTIE-ND accurately predicted stand-level mean GLI (Gap Light Index) under a range of harvest intensities. The model was then used to simulate nine silvicultural treatments based on combinations of three intensities of overstory removal (30%, 45% and 60% of basal area) and three harvest patterns (uniform, narrow strips, large gaps). Simulations showed that increasing overstory removal had less impact on light conditions with uniform harvests, and a more marked effect with more aggregated harvest patterns. Whatever the harvest intensity, uniform cuts almost never created high light conditions (GLI > 50%). Gap cuts, on the other hand, resulted in up to 40% of microsites receiving GLI > 50%. Our results suggest that either a 30% strip or gap cut or a 45–60% uniform partial harvest could be used to accelerate the transition from an aspen dominated composition to a mixedwood stand because both types of cut generate the greatest proportion of moderately low light levels (e.g., 15–40% GLI). These light levels tend to favour an accelerated growth response among shade-tolerant conifers, while preventing excessive recruitment of shade-intolerant species. A better understanding of how spatial patterns of harvest interact with tree removal intensity to affect understory light conditions can provide opportunities for designing silvicultural prescriptions that are tailored to species’ traits and better suited to meet a variety of management objectives

The State of Coral Reef Ecosystems of Southeast Florida

The northern extension of the Florida reef tract and a complex of limestone ridges run parallel to the subtropical Atlantic coastline of southeast Florida. Spanning 170 km from the northern border of Biscayne National Park (BNP) in Miami-Dade County to the St. Lucie Inlet in Martin County, the reefs and hardbottom areas in this region support a rich and diverse biological community (Figure 5.1). Nearshore reef habitats in southeast Florida include hardbottom areas, patch reefs and worm reefs (Phragmatopoma spp.) exhibiting abundant octocoral, macroalgae, stony coral and sponge assemblages. Offshore, coral reef associated biotic assemblages occur on linear Holocene Acropora palmata mid-shelf and shelf margin reefs that extend from Miami Dade County to Palm Beach County (Lighty, 1977; Figure 5.2). Anastasia Formation limestone ridges and terraces colonized by reef biota characterize the reefs from Palm Beach County to Martin County (Cooke and Mossom, 1929). The coastal region of southeast Florida is highly developed, containing one third of Florida’s population of 16 million people (U.S. Census Bureau, 2006). Many southeast Florida reefs are located just 1.5 km from this urbanized shoreline. Despite their unique position as the highest latitude reefs along the western Atlantic seaboard, the reefs of southeast Florida have only recently received limited scientific and resource management attention. Andrews et al. (2005) discussed the reefs of southeast Florida and the critical need to implement actions that fill resource knowledge gaps and address conservation and threats to reef health. This report further examines and updates the list of stressors imperiling the health of southeast Florida’s reefs, and presents information gained from new research, monitoring and management efforts to determine the extent and condition of reef resources in this distinctive region

Validation of Computationally Efficient Simulations of Douglas Fir Pyrolysis and Combustion Using Time-Resolved Frequency Comb Laser Measurements

Computational simulations have the potential to provide low-cost, low-risk insights into wildland fire structure and dynamics. Simulation accuracy is limited, however, by the difficulty of modeling physical processes that span a wide range of spatial scales. These processes include heat transfer via radiation and turbulent advection, as well as both solid- and gas-phase chemistry. In the present study, we perform large eddy simulation (LES) with adaptive mesh refinement to model the multi-phase pyrolysis and combustion of dry Douglas fir, where temperature-based lookup tables corresponding to a multi-step pyrolysis mechanism are used to represent the composition of gas-phase pyrolysis products. Gas-phase and surface temperatures, mass loss, and water vapor mole fraction from the LES are shown to compare favorably with experimental measurements of a radiatively heated Douglas fir fuel sample undergoing pyrolysis and combustion beneath a cone calorimeter. Using frequency comb laser diagnostics, optical and infrared cameras, and a load cell, the experiments provide simultaneous in situ, time-resolved measurements of chemical composition, temperature, and mass loss. The present study thus combines cutting edge computational and experimental techniques with multi-step chemical pyrolysis modeling to provide a validated computational tool for the prediction of solid fuel pyrolysis and combustion relevant to wildland fires. &nbsp;</p

Concise total syntheses of (–)-jorunnamycin A and (–)-jorumycin enabled by asymmetric catalysis

The bis-tetrahydroisoquinoline (bis-THIQ) natural products have been studied intensively over the past four decades for their exceptionally potent anticancer activity, in addition to strong gram-positive and -negative antibiotic character. Synthetic strategies toward these complex polycyclic compounds have relied heavily on electrophilic aromatic chemistry, such as the Pictet-Spengler reaction, that mimics their biosynthetic pathways. Herein we report an approach to two bis-THIQ natural products, jorunnamycin A and jorumycin, that instead harnesses the power of modern transition-metal catalysis for the three major bond-forming events and proceeds with high efficiency (15 and 16 steps, respectively). By breaking from biomimicry, this strategy allows for the preparation of a more diverse set of non-natural analogs

Concise total syntheses of (–)-jorunnamycin A and (–)-jorumycin enabled by asymmetric catalysis

The bis-tetrahydroisoquinoline (bis-THIQ) natural products have been studied intensively over the past four decades for their exceptionally potent anticancer activity, in addition to strong gram-positive and -negative antibiotic character. Synthetic strategies toward these complex polycyclic compounds have relied heavily on electrophilic aromatic chemistry, such as the Pictet-Spengler reaction, that mimics their biosynthetic pathways. Herein we report an approach to two bis-THIQ natural products, jorunnamycin A and jorumycin, that instead harnesses the power of modern transition-metal catalysis for the three major bond-forming events and proceeds with high efficiency (15 and 16 steps, respectively). By breaking from biomimicry, this strategy allows for the preparation of a more diverse set of non-natural analogs