Vernet Lab

The project seeks to evaluate pelagic-benthic communities in the area of the recently retreated Larsen C ice shelf in order to characterize the initial conditions of the coastal ecosystem exposed after millennia of being covered by ice. The team worked with the Korean Polar Research Institute, KOPRI, scientists in an international effort to sample in the lead developed between the Larsen C ice shelf and the A-68 iceberg to characterize water column, benthic and surface sediments of an under-ice ecosystem, and will sample seaward of the iceberg, to provide open-ocean ecosystem comparisons.

The cruise did not reach Larsen C due to very unfavorable ice conditions. However, we did take the opportunity and utilized our remaining ship time to study another massive iceberg (A-57 A) which also originated from the Larsen area.  Currently, the long-term impact of accelerated warming on sea level rise has been extensively studied, however the more immediate influence of glacial input on phytoplankton ecology and food web is still not well understood. By studying these icebergs in the aftermath of ice shelf collapse, we can achieve a better understanding of the direct impact of climate warming on polar ecosystems and biogeochemistry.

In collaboration with Dr. M.R. Cape, University of Washington, Seattle 

Funded by the National Science Foundation, Office of Polar Programs

Marine communities along the Western Antarctic Peninsula (WAP) are highly productive ecosystems which support a diverse assemblage of charismatic animals such as penguins, seals, and whales as well as commercial fisheries including for Antarctic krill. The WAP also contains many fjords (deep estuaries carved by glacial ice) with active glaciers entering the ocean; these fjords appear to be intense, potentially climate sensitive, hotspots of biological production and biodiversity. Because of intense biological activity and abundant charismatic fauna, these fjords are also major destinations for a large Antarctic tourism industry. Nonetheless, the structure and dynamics of these fjord ecosystems are very poorly understood.

The FjordEco project is an integrated field and modeling program designed to evaluate physical oceanographic processes, glacial inputs, water column community dynamics, and seafloor bottom community structure and function in these important yet little understood fjord systems. These Antarctic fjords have characteristics that are substantially different from well-studied Arctic fjords, likely yielding much different responses to climate warming. FjordEco is designed to provide major new insights into the dynamics and climate sensitivity of Antarctic fjord ecosystems, highlighting contrasts with Arctic sub-polar fjords, and potentially transforming our understanding of the ecological role of fjords in the rapidly warming west Antarctic coastal marine landscape. Our project will also further the NSF goal of training new generations of scientists, providing scientific training for undergraduate, graduate and postdoctoral students. This includes the unique educational opportunity for undergraduates to participate in research cruises in Antarctica and the development of a novel summer graduate course on fjord ecosystems. Internet-based outreach activities will be enhanced and extended by the participation of a professional photographer who will produce magazine articles, websites, radio broadcasts, and other forms of public outreach on the fascinating Antarctic ecosystem.

 FjordEco involves a 15-month field program to test mechanistic hypotheses concerning oceanographic and glaciological forcing, and phytoplankton and benthic community response in the Antarctic fjords. Those efforts will be followed by a coupled physical/biological modeling effort study to evaluate the drivers of biogeochemical cycles in the fjords and to explore their potential sensitivity to enhanced meltwater and sediment inputs. Fieldwork over two oceanographic cruises aboard the NSF ships the Laurence M. Gould and the Nathaniel B. Palmer in late 2015 and the spring of 2016 will utilize moorings, weather stations, and glacial, sea-ice and seafloor time-lapse cameras to obtain an integrated view of fjord ecosystem processes. The field team will also make multiple shipboard measurements and will use towed and autonomous underwater vehicles to intensively evaluate fjord ecosystem structure and function during spring/summer and autumn seasons. These integrated field and modeling studies are expected to elucidate fundamental properties of water column and sea bottom ecosystem structure and function in the fjords, and to identify key physical-chemical-glaciological forcing in these rapidly warming ecosystems.

Funded by the National Science Foundation, Office of Polar Programs

Carbon Bridge addresses how the main driver of climate change, the Atlantic inflow, impact productivity and carbon cycling in an area where future projections identify potential substantial changes in productivity due to ice retreat. The project positions itself in the inflow of Atlantic water (AW) along the shelf break region and Arctic Ocean (AO) north of Svalbard. New knowledge on Arctic marine ecosystems will be obtained through a multidisciplinary Earth System Science (ESS) approach including the hydrosphere, cryosphere, biosphere, atmosphere, geosphere and anthroposphere. More specifically, we investigate how the hydrosphere (AW inflow, water column stability and vertical structure) and the cryosphere (influencing stratification, light) act as drivers for the biosphere through changes in productivity and flow of energy through the so-called classical and microbial foodwebs and consequences for vertical carbon export. The fate of primary production is a key to understand the role of the warming AO as CO2 sink or link through carbon export, alkalinity and ocean-atmosphere exchange. Integrated data obtained in Carbon Bridge is being used for improved future projections of productivity to identify high- or low productive regions, and evaluate the ecosystem services and the value of the region for the anthroposphere. This new knowledge will be highly relevant for management and risk assessment necessary for future activities. In this way, Carbon Bridge contributes to increased understanding of physical-biological coupled processes, built around long term observational data and physical-biological coupled modelling, to better evaluate the present state, and future perspectives of ecosystem functioning and carbon cycling.

Results are being published in Frontiers in Marine Science - Research Topic, Carbon Bridge to the Arctic: https://www.frontiersin.org/research-topics/7672/carbon-bridge-to-the-arctic

Project funded by the Norwegian Research Council to Dr. Marit Reigstad, University of the Arctic in Norway.

Arctic and sub-Arctic glacial fjords are hotspots of secondary productivity, rich in seabirds, marine mammals, and fishes, potentially supported by local primary productivity. In this way, phytoplankton productivity is the link between hunting by Greenland’s Inuits and the ice sheet dynamics, in particular meltwater released to the surface ocean.  Recent studies indicate that Greenland Ice Sheet surface melt has the potential to increase subglacial meltwater delivery, promoting upwelling at the glacial-ocean front that results in nutrient fertilization at the fjord’s surface waters, potentially increasing productivity. The question is then, how does the meltwater delivery and existing nutrients drive the primary production within the fjord? Rates of productivity as well as its spatial distribution, in conjunction with physical and chemical properties, are needed to provide a first-order understanding of plankton processes within the fjord. I will participate in a 10-day cruise to Greenland’s fjord Sermilik to add plankton studies to an existing project on ocean-glacial dynamics and its impacts on local ocean circulation, a project that Dr. Fiamma Straneo has developed in the last 10 years. This project will develop a collaborative multi-disciplinary research within the umbrella of the new SIO Polar Center. The collected data will provide preliminary data to generate much-needed hypotheses on biological-physical interactions in the fjord in order to establish the relationship between ice sheet-ocean-ecosystem dynamics and expected changes that impact local Greenlander community subsistence, fishing and hunting.

Funded by the Academic Senate, University of California San Diego

The Weddell Gyre is one of the main oceanographic features in the ocean surrounding Antarctica, the Southern Ocean. Although located far from other continents, this polar region affects the planet through the exchange of gases between frigid ocean waters and the atmosphere, regulating oxygen and carbon dioxide farther north. Studying the Weddell Gyre is challenging, as sea ice covers the ocean surface year around, restricting access by research ships and sensing of ocean surface from satellites. New technology is now available to avoid past limitations, autonomous underwater vehicles, instruments flown by planes, and floats instrumented with sea‐ice detection. Only through international collaboration can we obtain adequate data to populate environmental models and study key areas in the gyre or hot spots. In this review we identify the missing links in our knowledge of the gyre, proposing research to address those questions. Three aspects are critical to understanding the processes that drive the gyre's oceanography, ice, geology, chemistry, and biology: winter and under‐ice conditions that set the stage for the evolution of physics, ice, and biogeochemistry; exchange of water, material, and energy (or heat) with lower latitudes; and intensification of the clockwise circulation of the gyre with changes in winds.

From Vernet et al., Review of Geophysics, DOI:10.1029/2018RG000604

The 2008 mean vertically integrated transport streamfunction in Sv from a 1/3° run with 52 vertical levels and from a 1/12° run with 104 vertical levels. The contour interval is 20 Sv. The Weddell Gyre circulation is much stronger in the 1/12° simulation, with a 2008 mean transport of about 45 Sv in the 1/3° and about 75 Sv in the 1/12°. Moreover, even in the annual mean it is clear that eddy fluxes between the WG and the ACC are extremely different. Model output available at sose.ucsd.edu (Courtesy of Matt Mazloff, SIO)

The ongoing changes in the circulation of the Subarctic Atlantic are, without question, impacting its marine ecosystems, yet our quantitative understanding of such ecological change(s) remains meager. A fundamental challenge is to predict whether net primary production (NetPP) in this region will increase or decrease under changing northerly and southerly advective flows. Here, we suggest that the balance will depend on regional bottom-up drivers (e.g., stratification, nutrient and light availability, community composition) and top-down drivers (e.g., grazing).

A growing understanding of the surface and deep overflows, counterflows, and recirculation patterns within the Subarctic Atlantic is emerging that indicates stronger influences of the Atlantic surface Water (AW) and Arctic-origin Water (ArW) on each other and on the average circulation patterns within the Subarctic Atlantic than previously thought. We define the Subarctic Atlantic as the region encompassed by the Greenland-Iceland-Norwegian (GIN), Irminger and Labrador Seas, where warmer and saltier AW—laden with nutrients, plankton and detritus—moves north in multiple branches into the Labrador Sea, into the GIN Seas and, eventually, into the Arctic Ocean. Fresher and colder ArW—with sea ice, low nutrients, low plankton and high colored dissolved organic matter—moves southwards along the edge of the eastern Greenland and western Labrador Seas and into the N. Atlantic. 

We focus on the balance of NetPP in the Subarctic Atlantic as affected by (i) advective losses and gains within this region at large-scales interaction with respect to boundary conditions in the temperate N. Atlantic and Arctic Oceans; (ii) lateral and vertical “export” production within sub-regions of the Subarctic Atlantic at intermediate scales; and (iii) advective and local processes controlling NetPP in the Subarctic Atlantic region. Our questions include the following:

(Q1) What bottom-up (physical and chemical) factors control the NetPP levels in the Subarctic Atlantic, where and when?

(Q2) What is the balance between local and advected NetPP in the Subarctic Atlantic during the growth season?

We use a hierarchy of models including a full 3D, coupled, biogeochemical-physical model at regional scale (SINMOD, SINTEF, Norway) and a specialized 1D satellite ocean color model for phytoplankton NetPP (UQAR-Takuvik, Canada), both of which are exceptionally well tuned to high latitudes. Model simulations are done in concert with mining historical field and satellite data to better understand the temporal evolution of NetPP and its physical and ecological controls over an average annual cycle in the Subarctic Atlantic 

Project funded by NASA ROSES 2015 A.3 OBB (amended) activity 2.3 “Research In Support of the Galway Statement: North Atlantic-Arctic Oceanographic Processes” to P.A. Matrai, Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine; M. Vernet, co-PI.

Seasonal Phytoplankton Gross Primary Production (GPP) estimated g C m-2d-1 from April to September 2012. Low production (in blue) and high production (in red), from 20 to 200 g C m-2d-1) for the study area.