Abstract:

The European eel is an iconic, migratory species that grows in the inland and coastal waters of Europe and North Africa, but reproduces in the Sargasso Sea, a large region in the western North Atlantic. Its complex life cycle makes the species vulnerable to various aspects of global change, which, together with overexploitation, have led to a drastic decline of the eel population in recent decades. At the same time, eel stock assessment is complicated by the scattered distribution into countless local stocks during the continental life phase, and the absence of a stock-recruitment relationship on the site-level. Leander will introduce us to the approaches and challenges in eel stock assessment and how management of this species is organized in Europe. He will present his recent work on a large-scale Bayesian stock assessment model and a management strategy evaluation to inform a long-term management plan for eel in the Mediterranean area.

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https://umassd.zoom.us/j/93758230260

Meeting ID: 937 5823 0260

Passcode:426839

Abstract:

In modern Southern Ocean surface waters, inefficient nutrient consumption by phytoplankton leads to high residual nitrate and silicate concentrations, with the implication that a stronger biological pump would sequester more atmospheric CO2. As the dominant phytoplankton type in the Southern Ocean, diatoms are major contributors to the biological pump. However, silicification and growth rates may vary significantly among diatom species, which affects each species’ carbon sequestration potential. We collected water column samples from the 2024 spring bloom at eleven stations along a south-north transect at 170°W in the Southern Ocean, spaced roughly every degree of latitude and spanning three frontal zones: the Antarctic Zone, the Polar Frontal Zone, and the Subantarctic Zone. We also conducted shipboard diatom culturing experiments under elevated nutrient treatments from each zone. The fluorescent dye PDMPO was used to quantify diatom silicification rates in field samples and in shipboard culture experiments. Diatom silicification rates were observed to be highest between 60-62°S, slightly north of the heart of the bloom. Results from shipboard culture experiments indicate that diatom silicification rates increased with access to excess ammonium and, to a lesser degree, silicic acid. These data will be used to explore the relationships amongst diatom species, nutrient supply, and silicification across the 2024 spring bloom.

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https://umassd.zoom.us/j/97440069270

Meeting ID: 974 4006 9270

Passcode: 428029

Abstract:

The Arctic Ocean is accumulating heat at an unprecedented rate, yet most of that heat does not immediately escape to the atmosphere. What determines when and how the ocean finally releases this energy? Using five years of Saildrone uncrewed surface vehicle observations across the Bering, Chukchi, and Beaufort Seas, this seminar shows that the decisive control is atmospheric near-surface stability.

During summer, the Arctic atmospheric marine boundary layer is predominantly near-neutral, a regime in which traditional bulk flux algorithms—developed largely in tropical and mid-latitude conditions—show their largest uncertainties. Cold-air advection events generate unstable boundary layers, deep turbulence, and efficient upward heat fluxes. In contrast, warm-air advection suppresses mixing, creating a stable “lid” that traps heat within the upper ocean for weeks to months.

This stability shift also produces a reversal in the sign of SST–turbulent heat flux coupling: the ocean controls the atmosphere under unstable conditions, but the atmosphere dominates under stable conditions. Additionally, stability shapes the ocean skin temperature structure, with warm-skin periods reducing flux estimates by roughly 9%.

Together, these results highlight stability—not wind speed or mean temperature—as the primary regulator of summer air–sea heat exchange in the Pacific Arctic, with implications for flux algorithms, satellite retrievals, and predictions of upper-ocean heat storage in a rapidly changing climate.

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Meeting ID: 974 4006 9270

Passcode: 428029

Abstract:

The Delaware Bayshore supports a broad diversity of marine life and migratory birds in addition to providing ecosystem services to its coastal communities. As the lowest mean-lying state in the US, Delaware’s coastline is also projected to experience profound change due to increasing sea level rise and extreme weather events. As practitioners in coastal resilience, we at The Nature Conservancy will share how we, along with our partners, approach ensuring these critical habitats remain productive through future climate change scenarios, as well as the challenges we face.

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https://umassd.zoom.us/j/93758230260

Meeting ID: 937 5823 0260

Passcode:426839

Abstract:

Observing the ocean’s kilometer-scale (i.e.,submesoscale) surface currents has been a long-standing challenge, with direct application to improving weather and climate models, marine navigation and a better understanding of ocean ecosystems. In this talk we review lessons learned measuring these currents during the NASA S-MODE campaign from both in situ assets such as wave gliders and doppler-based remote sensing techniques. The campaign highlighted that these spatially heterogeneous rapidly evolving submesoscale currents are particularly difficult to measure. To overcome this, we introduce Geostationary Ocean Flow (GOFLOW), a deep learning framework that produces hourly, high-resolution velocity fields from sequences of thermal imagery from geostationary satellites. Our approach directly measures the flow without assuming geostrophic balance and inherently filters internal wave noise that contaminates state-of-the-art satellite altimetry (e.g. the recently launched SWOT satellite). Applying GOFLOW to the Gulf Stream, we provide the first satellite-based measurements of submesoscale current statistics, revealing characteristic asymmetries in vorticity and divergence previously documented only in high-resolution circulation models. This ability to routinely map the ocean’s energetic submesoscale currents provides a new data source for advancing Earth system forecasting. 

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https://umassd.zoom.us/j/97440069270

Meeting ID: 974 4006 9270

Passcode: 428029

Abstract:

Highly dynamic spatial and temporal processes challenge our ability to study and manage ocean systems. My lab uses a multi-disciplinary, ocean ecology toolkit applied to top predators across a range of oceanographic regimes to understand how physical-biological interactions drive the structure and function of marine ecosystems. I will present our recent work linking predator movements to mesoscale eddies and highlight how a range of ocean dynamics modulate the connectivity between surface-oriented predators and the most abundant fish community on the planet in the twilight zone. Quantifying the interactions between predators, enigmatic deep ocean prey communities, and (sub)mesoscale ocean dynamics are requiring us to develop new tools to explore the ocean in unprecedented detail. Such advances are critically important for supporting sustainable resource management and marine spatial planning in a changing ocean.

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https://umassd.zoom.us/j/93758230260

Meeting ID: 937 5823 0260

Passcode:426839