Dr. Rehemat Bhatia, Foraminifera Geochemist

Rehemat looking at foraminifera under the microscope

What is your favorite part about being a scientist, and how did you become interested in science?

Throughout my time in middle school, my favourite lessons at school were always biology, chemistry and physics. I also really enjoyed physical geography, and  my teachers at school were always enthusiastic, engaging and were more than happy to support my interest in geology. They pointed me in the right direction with careers when I was in high school, and without their guidance I probably wouldn’t have studied geology at university. I also volunteered at the Natural History Museum in London from the beginning of my third year of undergrad with an EU funded research project called Throughflow (as part of the V Factor Volunteer Scheme). The researchers who I volunteered with were also incredibly encouraging and supportive, and great mentors too.

I enjoy being a scientist because:

  • I get to look at microfossil specimens that no one has looked at before. Foraminifera are so pretty, and I still can’t believe that these single celled organisms manage to create these ornate skeletons which record climate during their lifetime! Understanding the stories they have locked up inside is sometimes a little difficult, but I enjoy the challenge that this presents.
  • Lab work is fun. I love learning different chemical techniques.
  • I get to meet lots of awesome people from a variety of backgrounds and geological disciplines and talk science with them.
  • I get to communicate my science to public audiences and inspire new generations of scientists.

What do you do?

I use the chemistry of fossil plankton called foraminifera to understand more about their ecologies and what the climate was like millions of years ago.

How does your research contribute to the understanding of climate change, evolution, or to the betterment of society in general?

We use chemical data from foraminifera shells to reconstruct past climate. However, we don’t fully understand all aspects of foraminiferal ecology i.e. exactly what their lifestyles were like- did they all live with algae? Did they migrate or change in size because oceans became harder for them to live in? Ecology affects shell chemistry. Thus, before we put together long term climate records to understand how the earth’s climate has changed through time using chemical signals from foram skeletons, it is important to understand the controls on the signals that we use. This is particularly pertinent to geological periods that we use as future climate analogues such as the Eocene (~47-33 million years ago).

A picture of a foraminifera (taken with a microscope) that has been blasted with Rehemat’s laser! Where the holes are is where the laser was used to measure the different amounts of elements in the shell.

What are your data and how do you obtain them?

Planktonic foraminifera are single celled plankton which have a skeleton made from calcium carbonate. Some species choose to live in the surface waters of the ocean, whilst others choose to live in the thermocline. Some even live together with algae! All forams are beautiful, and they come in all sorts of shapes and sizes. Foraminifera are really awesome too, because in the same way human hair records our diet, their skeletons record the environmental conditions around them in the ocean. By the analysis of one shell, we can understand the climate in the location and the time that the foram lived, including how hot the oceans were and even how much ice there was on land!

When foraminifera die, their skeletons sink to the sea floor and build up in layers, creating an extensive fossil record more importantly an extensive climate record too! The same signals we use to infer climate in the past can tell us how they used to live too i.e. their ecology.

To understand foraminiferal ecology, I use several geochemical proxies. Proxies are chemical signatures which are an indirect way of understanding an environmental parameter. I primarily use  oxygen isotopes, carbon isotopes and the amounts of magnesium (Mg), strontium (Sr) and boron (B) (ratioed to calcium, Ca) in foraminiferal shells. If these elements are unfamiliar to you, you might not have realized you’ve seen them before. White fireworks have Mg, green fireworks have B and red fireworks have Sr! I gather these data using different machines called mass spectrometers and electron microprobes. One of the mass spectrometers I use is hooked up to a laser, which is super cool. I use the laser to drill through foram shells to understand how Mg, B and Sr vary through the shell wall. Mg/Ca, Sr/Ca, B/Ca, δ18O and δ13C signatures are specific to certain species. For example, a surface dwelling species will have greater Mg/Ca and a more negative δ18O signature. Therefore if I collected these type of data from a species with an unknown ecology, I would infer that it was a surface dweller.

What advice do you have for aspiring scientists?

  • Always be curious.
  • Ask as many questions as you can – no question is stupid. If someone tells you your question is stupid – they’re wrong.
  • Talk with lots of people who might be able to help you gain more of an insight into the world of science. You never know who might be able to give you work experience/research internships/jobs (both academic and non academic).
  • If things go wrong academically early in your career, don’t let that stop you from progressing later on. Work hard, learn from your mistakes, and you can do anything you’d like to (I speak from experience with this one…)
  • Have mentors and a support network. I wouldn’t have survived the final stages of my PhD without mine.
  • Look after yourself – no science is worth you burning out over. As a friend once told me – the forams will still be there and waiting for you to look at them in the morning… (they’re not wrong).
  • For those studying for exams (including PhDs): Don’t lose your enthusiasm and don’t give up if things get tough. You set out to learn/research something cool, and if you’ve made it this far, you can totally do it!

Learn more about Rehemat’s research and follow her on Twitter @rehemat_

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