Foraminifera as anthropogenic proxy in the Arctic

Micropaleontology/Laboratory/Benthic Foraminifera/Climate Change

Welcome to tiny world!

Hey! It's me Solenne. You can see me here happy opening moldy eggs from a green turtle nest. I put this old picture to show you how I am more a Field/Megafauna person than a Lab/Microfauna one. So why choose a Practice about zooplankton ? Because my mindset was to challenge myself acquiring and practicing new skills outside my comfort zone, with as a common thread my interest in Polar ecosystems in which I want to specialize! So I did a practice involving a lot of laboratory work, using countless hours of microscope daily to study zooplankton and get immersed in a tiny fossil world.

My goal ?

Investigating benthic foraminifera will help to improve understanding how climate change induced by human activity is affecting ocean and marine species. The Arctic appears to be a harbinger of environmental change particularly changes in climate. My work will help to assess the potentially biodiversity lost due to anthropogenic climate change by comparing living and dead benthic foraminifera communities.

What is a foram ?

These microscopic and single-celled organisms are commonly widespread in all oceans. They get their name from latin word Foramen (means ‘opening’) referring to their shell apertures also called 'tests'. Because of their abundant fossil record (up to 500 million years ago), they are broadly used in paleoclimatology as a proxy to reconstruct past climate. Planktonic forams tell us about temperature change, benthic forams bottom environment change.

Source : Caridi et al. (2019)

Kveitola Through

From their 2016 Arctic expedition in Barents Sea, my research group collected ocean cores sediments in 8 locations at the Kveitola Trough. Numbers represents the locations where sampling was carried out. I studied 4 site locations : number 02, 05, 06 and 07. From their samples, a living benthic foram population study was done, and my complementary goal is to do a quantitative analysis on dead benthic assemblages.

My daily view and routine

Regarding the depth I was focusing on and the paleoclimatology scale, I was studying Anthropocene period. I was focusing on 3 morphogroups that I needed to identify : Calcareous (transparent shell), Porcelaneous (opaque shell) and Agglutinated (particles cemented shell).

Using a microscope, I needed to pick and count around 300 unbroken benthic foraminifera specimens in every samples from others organisms and rocks. Once I identify an individual, I pick it with a wet paint brush and put it in another box with smaller squares and number, so I can group them by morphogroup and fill my database with species abundance.

We know climate change accelerated the past 30 years and its greatest changes have been recorded in Arctic ocean, reducing extremely sea ice. The Arctic sea ice declines will lead to an increase of organic matters available and therefore enhance its productivity. So it is expected to find more opportunistic and organic matters dependent species in my samples.

How finding a needle in a haystack ?

Foraminifera are animals which build a shell called 'test', and for paleontologists the characteristics of the test are the primary features which can be used to distinguish one species from another. Porcelaneous (1) are characterized by their opaque high magnesium test. Calcareous (2) was the most abundant in my sample and is composed of either calcite or aragonite . Agglutinated (3), the geologically oldest method of test construction, is the agglutination of particles together to form an external covering.

1. Porcelaneous

3. Agglutinated

2. Calcareous

Let's make a QUIZ :

https://docs.google.com/presentation/d/1dMS6_rfaS9QZu7w5GTrNgprnT7IBdAT74xe7rNK4pCs/edit?usp=sharing