Imagine a world where the sun stops setting, the ice stretches endlessly, and beneath it, life thrives in unexpected ways. This was the backdrop for our 2024 Antarctic science field season - a journey into one of Earth's most extreme and awe-inspiring ecosystems.

What are we looking at?

This season our team focused on exploring the changing physical and biological properties of sub-ice platelet layer —a hidden, otherworldly environment beneath the Antarctic sea ice. This fragile layer is made up of loosely consolidated plate shape ice crystals, creating a unique habitat. The amazing upside-down reef-like structure can hold the highest concentrations of microalgae of any type of ice environment.

Left: a single platelet crystal. Mid: loosely consolidated platelet crystals on the bottom of sea ice [images - Jacqui Stuart] Right: The sub-ice platelet layer from below the ice, all the green/brown is microalgae! [Leigh Tate, NIWA]

Why are we doing this science?

Antarctica isn’t just the coldest place on Earth—it’s a barometer for our planet’s health. The changes happening here are a magnified reflection of global climate trends, making it a critical indicator of the broader state of our world. Platelet ice ecosystems are home to microalgae, which, along with microalgae in the water column and the sea ice, form the base of the food web in Antarctica. These tiny organisms support everything from krill to whales, connecting life under the ice to the entire marine ecosystem.

A composite photo of some microalgae species observed in the sub-ice platelet layer, showing just how diverse and beautify these important primary producers are. [Image – Jacqui Stuart].

What science did we do this season?

Because this sub-ice platelet environment is so delicate, to study this environment, a custom platelet sampler was designed by Dr. Craig Stewart as part of the Antarctic Science Platform. This is the second field season it has been successfully deployed and the system allows us to carefully extract full core samples from the platelet layer.

This season, we focused on the differences in platelet ice communities, both in general and over time, to better understand which bacteria, microalgae, zooplankton, and other larger organisms are spending time in or around the platelet layer. A key part of this work was an experiment to explore how varying amounts of snow on top of the sea ice influence the communities living within the platelet layer.

The platelet sampler in action [Images - Jacqui Stuart]

Why does snow matter?

Snow plays a critical role in shaping the environment beneath the ice. Acting like a blanket, it insulates the ice and alters both the light and temperature conditions below. These factors are essential for determining which organisms can thrive in the platelet layer. However, snow on sea ice typically accumulates through wind redistribution rather than direct snowfall, making its presence highly variable.

As climate change causes sea ice to form later in the season, the time available for snow to accumulate and for platelet layers to develop is reduced. This experiment aims to understand how changes in snow load might shift the composition and dynamics of the microbial and larger communities within the platelet layer. By simulating different snow loads, we hope to gain insights into how these ecosystems might respond to increasingly variable ice and snow conditions in the future, and what that means for the broader Antarctic food web.

The freshly set up snow load experiment, which involved a full nine-hour workday for four people to get the 10 cubic meters of snow moved where it needed to be! This was sampled over a three-week period to see how communities in the platelet ice were changing [Photo: Jacqui Stuart]

Stay Tuned

Antarctic science is a true collective effort, and we're excited to share our findings in the months ahead. A massive thank you to Antarctica New Zealand and all the Scott Base crew for their support this season.

If you want to learn more about platelet ice and this project, check out:

What is platelet ice? https://www.antarcticscienceplatform.org.nz/updates/platelet-ice-a-unique-and-fragile-antarctic-ecosystem

Platelet sampler in action video: https://www.youtube.com/watch?v=Q416Zl8WbpY