Under the sea by Florian Huber

Deep in the Red Sea off the Saudi Arabian coast, Nauras Daraghmeh (left) and Yusuf El-Khaled install an incubation chamber over part of one of the region’s precious underwater ecosystems — a coral-reef community. Nearby, freelance marine biologist Uli Kunz captures the delicate scene on film.

Nicknamed the 'coral probiotics village', the project, based at King Abdullah University of Science and Technology in Thuwal, Saudi Arabia, aims to investigate how different corals — such as Acropora species pictured here — are adapting to the rising water temperatures caused by climate change.

The chambers allow the researchers to study how the ecosystem functions by measuring the amount of oxygen consumed and produced by the corals and their symbiotic zooxanthellae — microscopic algae that live in their tissue and that of other marine species.

'In this photo, I wanted not only to capture the research divers in the midst of their often hectic work, but also to show a moment of quiet contemplation,' says Kunz.

Protecting gentle giants by Rob Harcourt

Diving down on a single breath, marine biologist Michael Doane carefully skims the skin of a whale shark (Rhincodon typus) with a syringe, collecting a sample of the microorganisms that dwell there. Behind him, a curious silvertip shark (Carcharhinus albimarginatus) swims into view.

This image was taken in April at Ningaloo Reef off the coast of Western Australia by Robert Harcourt, a marine ecologist at Australia’s Macquarie University in Sydney, who was on hand to document the event.

'Swimming next to a 12-metre whale shark as it cruises through the blue, gulping away and seemingly non-plussed by our presence is both humbling and exhilarating,' says Harcourt. 'The silvertip shark sneaking up on Mike got all our hearts racing — except Mike, who was focused on microbes,' he says, adding it was a reminder that the moment was 'unfolding within a broader, interconnected marine community'.

Standing against the bloom by Haolun (Allen) Tian

From the sky, the algal blooms on Dog Lake in Ontario, Canada, look like abstract art, swirling as creatures and objects pass by. But from a boat, it’s a different reality.

Microcystis aeruginosa and Dolichospermum flos-aquae — two algal species common to Canada — create a 'toxic, vile smelling layer of rot' on the lake each summer, according to Haolun ‘Allen’ Tian, a PhD student at Queen’s University in Kingston, Canada. The thick green bloom kills fish and clogs water supplies.

'During the fall, they actually rot and die,' Tian adds. 'Basically, there’s very few species that can eat them, so they don’t enter the food web.'

In the morning light of September 2021, the silhouette of Queen’s University master’s student Kelly Estrada Piedrahita stands out against the green as she collects water samples from the front of the boat. Behind her sits volunteer Shirley French, while Tian — the project’s lead — takes photos from the shore.

After collecting water samples from the lake, the team filters them and extracts and analyses the environmental DNA (eDNA). 'eDNA techniques are extremely sensitive and allow us to detect even just a few copies of DNA from species of interest,' says Tian. Using this information, they can then investigate how the algae interact with other lake species.

Captured in the glow by Shayanta Chowdhury

Under ultraviolet light, the yellow fever mosquito (Aedes aegypti) in Lee Haines’s microscope glows bright: a sign that it has fed on a sugar concoction spiked with a fluorescent dye and a mosquito-killing agent. Haines, an entomologist at the University of Notre Dame in Indiana, is part of a team studying how the drug nitisinone can be used to kill blood-feeding insects.

'The UV illumination created striking colours from both the tiny mosquito and the condensation that formed beneath the cold Petri dish,' says photographer Shayanta Chowdhury.

As a chemistry PhD student at Notre Dame, Chowdhury uses lasers and spectrometers to study molecules attached to nanoparticles. Although 'I don’t work with biological samples,' he says, 'I am always fascinated by their beauty under the microscope.'