A Tale of Two Blooms: Dynamics of Nitrogen Uptake by Harmful Algae in the Eastern Gulf of Mexico and York River, Virginia, USA

The goal of this study was to determine the significance of dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON) to harmful phytoplankton. Two regions that experience frequent and persistent harmful algal blooms (HABs) were examined, the Eastern Gulf of Mexico and York River, Virginia. Nitrogen uptake by harmful algae in these regions was examined using a combination of stable isotopic (15N) tracer techniques and nutrient bioassays. In the Eastern Gulf of Mexico, kinetic parameters for uptake of N substrates by K. brevis were determined and indicated the greatest preference for ammonium (NH4+), although all substrates tested were taken up. Investigation of N uptake by K. brevis in the light and dark revealed periodicity of diet uptake rates with the maximum and minimum rates measured early in the light and dark periods, respectively. The highest rates of uptake were observed for NH4+. Ratios of NH4+ regeneration:uptake were ∼1, indicating the importance of regeneration processes to blooms. Three strains of K. brevis exhibited significant differences in N uptake rates. The observed nutritional flexibility of K. brevis likely helps it flourish under a range of conditions spanning bloom initiation in oligotrophic offshore waters to bloom maintenance inshore. In the York River, N uptake was dominated by NH4+ with the highest uptake rates at all stations, for all size fractions and for all seasons, ranging from 34 to 80% of total absolute uptake. Rates of N uptake by A. monilatum are the first reported for this species in the York River, and demonstrate uptake of a diverse suite N substrates. During the A. monilatum bloom NH4+ regeneration rates equaled those of uptake, indicating the importance of regeneration to blooms. Additionally, three anthropogenic N sources were used to assess their role in exacerbation of a HAB during a 7 day bioassay. Urban parking lot run-off (+ Urban), soil from a construction site (+ Soil) and paper mill run-off (+ Industrial) were added to a natural bloom assemblage. Results indicated the anthropogenic sources had unique N compositions; DIN comprised ∼9%, 91% and 20% of + Urban, + Soil, and + Industrial, respectively. All N sources stimulated the growth of phytoplankton with the + Urban and + Soil treatments eliciting the greatest response, a doubling in Chl a and/or cell concentrations along with nutrient drawdown of both DIN and DON within two days. The results of this dissertation emphasize the importance of a flexible metabolism to the success of the HAB species investigated here. All harmful phytoplankton studied were able to utilize the variety of DIN and DON sources supplied. Additionally, a universal preference for NH4+ was observed in all studies despite the distinct regions examined and unique characteristics of each species

Three years of x+y scheduling: Longitudinal assessment of resident and faculty perceptions

PURPOSE: Five pediatric residency programs implemented true X+Y scheduling in 2018 where residents have continuity clinic in blocks rather than half-day per week experiences. We report the impact X+Y scheduling has on pediatric resident and faculty perceptions of patient care and other educational experiences over a three-year timeframe. METHODS: Electronic surveys were sent to residents and faculty of the participating programs prior to implementing X+Y scheduling and annually thereafter (2018 - 2021). Survey questions measured resident and faculty perception of continuity clinic schedule satisfaction and the impact of continuity clinic schedules on inpatient and subspecialty rotations. Data were analyzed using z-tests for proportion differences. RESULTS: 186 residents were sent the survey pre-implementation and 254-289 post-implementation with response rates ranging from 47%-69%. 378- 395 faculty members were sent the survey with response rates ranging from 26%-51%. Statistically significant (p\u3c0.05) sustained perceived improvements over three years with X+Y were seen in outpatient continuity, inpatient workflow, and time for teaching both inpatient and in continuity clinic. CONCLUSIONS: X+Y scheduling can lead to perceived improvements in various aspects of pediatric residency programs. Our study demonstrates these improvements have been sustained over three years in the participating programs. WHAT\u27S NEW: X+Y scheduling in pediatric residency programs is rather novel and there is a paucity of literature evaluating its use. We report three years of outcome data from the only ACGME-approved pilot of X+Y scheduling in pediatric residency

Impact of X+Y scheduling on pediatric resident and faculty perceptions of education and patient care

PURPOSE: Traditional half-day per week continuity clinic experiences can lead to fragmented education in both the inpatient and outpatient arenas. Five pediatric residency programs were granted the ability from the ACGME to create X+Y scheduling where residents have continuity clinic in blocks rather than half-day per week experiences. The aim of this study is to assess the impact X+Y scheduling has on pediatric resident and faculty perceptions of patient care and other educational experiences. METHODS: Electronic surveys were sent to residents and faculty of the participating programs both prior to and 12 months after implementing X+Y scheduling. Survey questions measured resident and faculty perception of continuity clinic schedule satisfaction and the impact of continuity clinic schedules on inpatient and subspecialty rotation experiences using a 5-point Likert Scale. Data were analyzed using z-tests for proportion differences for those answering Agree or Strongly Agree between baseline and post-implementation respondents. RESULTS:126 out of 186 residents (68%) responded pre-implementation and 120 out of 259 residents (47%) responded post-implementation. 384 faculty members were sent the survey with 51% response pre-implementation and 26% response at 12 months. Statistically significant (p CONCLUSIONS: From both resident and faculty perspectives, X+Y scheduling may improve several aspects of patient care and education. X+Y scheduling could be considered as a potential option by pediatric residency programs, especially if validated with more objective data

Blooms of \u3cem\u3eKarenia Brevis\u3c/em\u3e (Davis) G. Hansen & Ø. Moestrup on the West Florida Shelf: Nutrient Sources and Potential Management Strategies Based on a Multi-Year Regional Study

Identification and quantification of the nutrient sources supporting large, extended duration Karenia brevis blooms on the West Florida Shelf (WFS) in the eastern Gulf of Mexico are critical steps for effective bloom management and mitigation. Previous research had identified multiple (\u3e 12) potential nutrient sources available to K. brevis blooms on the WFS, which vary with bloom stage, location, biomass and bloom toxicity. This current study newly identified and quantified additional nitrogen (N) sources including water column nitrification, photochemical nutrient production, pelagic unicell N2 fixation by diazotrophs other than the colonial cyanobacterium Trichodesmium, and remineralization from seasonal Trichodesmium biomass decay and microzooplankton grazing (and estimated regeneration). Newly identified phosphorus (P) sources include remineralization from Trichodesmium biomass decay and microzooplankton grazing. In estuarine environments, benthic nutrient flux, mixotrophic consumption of picoplankton, nutrient release from zooplankton and microzooplankton grazing, photochemical nutrient production, and nitrification all can contribute up to 100% of the N and/or P requirements of small (\u3c 105 cells L−1) K. brevis blooms. During average estuarine flow years, combined estuarine sources contribute up to 17 and 69% of the N and P needs of these blooms, however local estuarine contribution can increase to 100% for exceptional, high flow years. In coastal and offshore environments, regenerated nutrient sources become increasingly important to blooms, with zooplankton excretion, nitrification, decay and regeneration of nutrients from dead fish and pelagic N2 fixation potentially providing 100% of bloom N and P needs. During the largest observed coastal blooms (14.0 × 106 cells L−1) N2 fixation and release and decay of seasonal Trichodesmium bloom biomass were the only sources of N and P that were completely sufficient to support blooms of that magnitude. Given the complexity of K. brevis bloom dynamics, the multiple available nutrient sources on the WFS and the importance of regenerated N forms in supporting blooms, efforts to reduce potentially controllable nearshore nutrient inputs should be undertaken with the understanding that while they may lead to enhanced coastal water quality, they may not have an immediate impact on the frequency or magnitude of nearshore K. brevis blooms. Additionally, time lags in ecosystem responses or differences in the time scales on which various process operate may require multi-year assessments to determine how effective management practices are in relation to K. brevis blooms. Timely red tide related monitoring products that allow for effective focusing of monitoring needs for short-term prediction of impacts and targeted communication of scientific results to the public and stakeholders, remains the most effective means of K. brevis management