Focus 1: Export Marine Export Production and Atmospheric Dust
Export production, or the flux of particulate organic carbon produced by plankton in the upper ocean that escapes to deeper waters, is an important component of the global carbon cycle and a primary source of nutrients for biological communities in the deep ocean. Knowledge of real time dynamics between dust input, primary production, and export production in deep nutrient poor waters is poor, and suffers from limited real-time observational support. The Gulf of Eilat (Gulf of Aqaba), in the northern Red Sea, is an oligotrophic, marginal sea characterized by high deposition rates of atmospheric dust, whose partial dissolution is thought to supply nutrients, including iron, to surface waters. Together with my colleague Adi Torfstein at the Interuniversity Institute for Marine Sciences in Eilat (http://iui-eilat.ac.il/People/AcademicStaffProfile.aspx?sid=184), my group is testing the connection between atmospheric dust input and export production fluxes by coupling real-time, high temporal resolution sampling of atmospheric dust and settling particulates in the Gulf. Between 2015-2017, we quantify seasonal fluxes and abrupt events such as dust storms and flash floods. The composition of settling particles will be compared to that of recently deposited sediments to investigate the water–sediment signal transfer. These results in turn will be used to inform a reconstruction of past dust and export production fluxes in the GOE over the last millennia based on sediment cores.
Focus 2: Sea surface temperatures and storminess in the western N-Atlantic over the last 2000 years
The coast of Atlantic Canada is subject to two types of storms, extratropical, north-eastwards travelling cyclones and tropical cyclones, or their remnants. Based on a range of model simulations, storm events are predicted to have an ever-increasing impact on people, property, infrastructure, wildlife and eco-systems along the Atlantic provinces of Canada. However, climate projections, especially those of extreme events, are inherently uncertain. One reasons for this uncertainty is the short length of the instrumental record available to validate hind-casts. In the Halifax region, for example, daily record keeping of temperature and precipitation has started in 1871, and information on winds has only been systematically collected since 1955. Yet marine sediments accumulating in selected locations on the shelf offer high temporal resolution and likely hold valuable paleo climate information. My students Erin Wilson and Alexandra McKenchie are investigating organic biomarkers and inorganic grain size patterns to generate a temporal of sea surface temperature and bottom water movement (related to high wave activity and storminess) over the last 2000 years in this area.
Focus3: Resolving the controversy revolving around particle flux reconstructions and sediment focusing
In some parts of the oceans, sediment particles are redistributed laterally on the sea floor by bottom currents. This makes extracting paleo information from marine sediment cores more challenging. My student Diksha Bista has investigated the inorganic grain size composition of sediment cores in the eastern tropical Pacific and is testing whether sedimentological indicators of sediment movement support geochemical indicators of lateral transport on the sea floor in this region.