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BIO Coffee Talks: November 2019
Who: Vincent Sieban
Dalhousie University
What: Moving Lab on Chip Systems to the Field
At present, only a single nutrient, nitrate, can be measured from Argo floats. Unfortunately, these nitrate analyzers are too expensive, slowing expansion of the international biogeochemical (BGC) Argo program. The lack of low-cost and small nutrient sensors suitable for payload constrained platforms has resulted in severe under-sampling of the world's oceans, both spatially and temporally. In this talk, we highlight our research advances and recent progress toward creating lab-on-chip nanomolar capable sensors applied to marine environments. We will present our reagent-based in situ microfluidic nitrate and phosphate sensors, which make use of embedded micro-prisms that direct light into a custom inlaid optical absorbance cell. This approach permits the optical elements and supporting electronics to be decoupled from the microfluidic chip itself, speeding up development of the novel chip technologies. The core-optical cell has been combined with integrated microvalves, an external pumping system and embedded electronics to yield fully automated nitrate and phosphate sensors. The sensors have been characterized on-bench with limits of detection (LOD) that are 40 nM (nitrate) and 100 nM (phosphate) using 25mm optical path lengths. We have also deployed the sensors in the Bedford Basin in Halifax, Canada capturing a notable nutrient increase after Hurricane Dorian passed Nova Scotia. Beyond the nutrient sensors, the talk will also cover our group's work in applying lab-on-chip technologies toward environmental DNA monitoring and to crude oil characterization. Inexpensive and versatile lab-on-chip sensors will allow us to quickly, effectively, and accurately monitor ocean biogeochemistry over a wide range of deployment scenarios and across an array of locations.
When: Friday, November 29, 2019
Where: 10am, Needler Boardroom, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: David Greenberg 1 and Florent Lyard 2
1Bedford Institute of Oceanography, Canada
2LEGOS, Université de Toulouse, France
What: A Laptop Tide-Surge Model for the Northwest Atlantic
We use T-UGOm, (Toulouse Unstructured Grid Ocean model) in non-linear, 2D time stepping mode to look at the combined surge and tide driving sea level of the Northwest Atlantic Coast. The January - March, calendar year 2014 is examined. The tides are driven by specified open boundary constituents, gravitational forcing, loading and self - attraction. Wind stress and sea surface pressure are obtained from archived ECMWF ERA5 hourly data filtered to reduce sub 6 - hourly information that can cause spurious responses. The inverted barometer effect is added to open boundary tides. We calibrate using constituents at crossover points from satellite altimetry and compare model results to coastal tidal records and constituents from tide gauges. The influence of the meteorological forcing on tidal constituents is investigated as well as the tidal and meteorological forcing of the barotropic mean circulation.
When: Friday, November 22, 2019
Where: 10am, Needler Boardroom, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Dong Wang
Bedford Institute of Oceanography
What: Langmuir Turbulence in Hurricane Conditions
The interaction of surface gravity waves with ocean currents generates an oceanic process called Langmuir turbulence (LT). LT is widely distributed in the open ocean, coastal regions, and even big lakes, and is often easily identified by parallel bands of sea surface debris along the wind directions or wave directions with spacing that varies from several meters to dozens of meters, as shown in the figures below. LT features coherent vortex structures, which significantly enhance the upper ocean mixing and critically influence the vertical distributions of nutrients and pollutants.
In this talk, I will assess Langmuir turbulence and its impact on upper ocean processes in hurricane conditions, aiming to better understand the air-sea interactions with waves, and thus contribute to better skill in hurricane prediction. Our study uses numerical models to simulate the wind, waves, and ocean current fields under hurricanes, which are developed, based on first principles of momentum and mass conservation and tuned to the observations. Our results show that LT generally enhances sea-surface cooling through greater cold-water entrainment from the deep ocean layer. However, such enhanced sea-surface cooling does not always occur, and the necessary conditions for the enhancement are discussed. I will also briefly describe my ongoing research over the next year at BIO.
When: Friday, November 15, 2019
Where: 10am, Needler Boardroom, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Dong Wang
Bedford Institute of Oceanography
What: Langmuir Turbulence in Hurricane Conditions
The interaction of surface gravity waves with ocean currents generates an oceanic process called Langmuir turbulence (LT). LT is widely distributed in the open ocean, coastal regions, and even big lakes, and is often easily identified by parallel bands of sea surface debris along the wind directions or wave directions with spacing that varies from several meters to dozens of meters, as shown in the figures below. LT features coherent vortex structures, which significantly enhance the upper ocean mixing and critically influence the vertical distributions of nutrients and pollutants.
In this talk, I will assess Langmuir turbulence and its impact on upper ocean processes in hurricane conditions, aiming to better understand the air-sea interactions with waves, and thus contribute to better skill in hurricane prediction. Our study uses numerical models to simulate the wind, waves, and ocean current fields under hurricanes, which are developed, based on first principles of momentum and mass conservation and tuned to the observations. Our results show that LT generally enhances sea-surface cooling through greater cold-water entrainment from the deep ocean layer. However, such enhanced sea-surface cooling does not always occur, and the necessary conditions for the enhancement are discussed. I will also briefly describe my ongoing research over the next year at BIO.
When: Friday, November 15, 2019
Where: 10am, Needler Boardroom, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Adina Paytan
University of California Santa Cruz and 2019 Huntsman Award Recipient
What: Aerosol Impacts on Marine Ecosystems
Atmospheric deposition of trace elements and nutrients to the ocean can significantly modify seawater chemistry and influence oceanic productivity. However, mounting evidence suggests that the response of phytoplankton to atmospheric deposition depends on the chemical composition of the aerosols and varies across different phytoplankton species. Responses are also different depending on oceanographic setting and season. To determine if and how nutrients and metals from atmospheric deposition influence phytoplankton community structure in the Ocean we analyzed nutrient (nitrogen and phosphorous) and metal (Fe, Cu, Zn, Ni) concentrations in marine aerosols and tested how these constituents impact phytoplankton. This is done using incubation experiments with natural phytoplankton assemblages with different sources and amounts of aerosol or pure nutrients and metal additions. Laboratory-based culture experiments with phytoplankton from different taxonomic groups helped identify species that were most sensitive to aerosol additions. Variance in utilization of nutrients and susceptibility to metal toxicity was identified among different taxa, suggesting that aerosol deposition could potentially alter patterns of marine primary production and phytoplankton community structure. In addition, input of bio-aerosols can also affect phytoplankton communities and should be considered. Changes in atmospheric deposition and aerosol composition that are impacted from natural and anthropogenic change could therefore have effects on ocean chemistry and productivity with potential feedbacks to the carbon cycle.
When: Friday, November 8, 2019
Where: 10am, King Boardroom, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Dr. Paul Regular
DFO Science, Newfoundland and Labrador Region
What: Interactive Tools for Science Advice
Scientists across many fields are faced with the challenge of synthesizing and communicating information from large and complex data sets. This growth in data, alongside the computational methods used to integrate it, can make the process of communicating the results to stakeholders and managers in a meaningful way more daunting. The traditional approach of presenting information across a series of static slides and plots often fails to convey the richness of information available and, as such, important patterns and details are easily overlooked. This problem can be mediated through the effective use of new open source tools for building interactive visualizations. These tools allow a broader audience to conduct detailed explorations of the results, leading to a deeper and collective understanding of both the data and models used to inform Science advice. As a consequence, the peer review process is more open and accessible and the resulting science advice is improved and widely supported.
When: Wednesday, November 6, 2019
Where: 10am, Hayes Boardroom, Fish Lab FL-117, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Mette Dalgaard Agersted
Institute of Marine Research, Bergen, Norway
What: Using acoustic methods to study ecology in the mesopelagic zone
The mesopelagic community has the potential to meet the future food demand by the world's population. Yet, the biomass and ecological role of the mesopelagic ecosystem are largely unknown. Acoustic techniques are non-invasive and thus ideal to study organisms in situ. By lowering acoustic instruments into layers of interest, we can obtain unique data on behavior and distribution patterns of the organisms. Broadband acoustic systems measure acoustic backscatter from organisms over a wide range of frequencies and increase the range resolution compared to narrowband systems. This increases the ability to separate targets in dense layers and to obtain accurate target strength measurements, which are essential for deriving acoustic abundance estimates.
A submersed towed platform (MESSOR) equipped with both narrowband (38kHz) and broadband echo sounders (50 to 260 kHz), CTD, an optical plankton counter (OPC) and a video plankton recorder (VPR) was used in combination with trawls to collect data from 0-1000 meters depth in the NE Atlantic. In this talk, I will present some acoustic characteristics of mesopelagic organisms and demonstrate that broadband acoustics can be used in combination with theoretical scattering models, trawl catches and images to identify and verify different organisms. Furthermore, the acoustic measurements are used to estimate the vertical abundance of organisms in the mesopelagic zone, which can further be coupled to biological and physical components for a better understanding of the ecosystem structure.
I will furthermore present some data where acoustic methods were used to study vertical and spatial distribution of zooplankton in East- and West Greenland, respectively. This data will be used to investigate distribution patterns in relation to the presence of their predators: little auks and bowhead whales.
When: Friday, November 1, 2019
Where: 10am, King Boardroom, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
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