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Original article: https://theconversation.com/from-a-salty-breeze-to-the-stench-of-sewage-heres-how-smell-affects-our-ocean-experience-and-reflects-changing-seas-239022
Apart from the breathtaking sight of vast blue waters or the rhythmic sound of crashing waves, the vivid smell of the sea ties us to the rhythms of nature and the ebb and flow of the tides. The salty freshness of a coastal breeze or the distinctive scent of seaweed can transport us back to memories of seaside holidays, fishing trips, or childhood adventures.
A “smellscape” is the perceived smell environment which can be fleeting or may build over time, depending on our past experiences and backgrounds.
My research investigates how smells trigger feelings, imaginations and memories in places. As geographer Paul W. Rodaway noted 30 years ago, “olfaction gives us not just a sensuous geography of places and spatial relationships, but also an emotional one of love and hate, pain and joy, attachment and alienation”.
There’s no single ocean smell. Smellscapes of the sea are multi-layered; they are shaped by interactions between water, marine life and environmental conditions. Every time we breathe in sea air, we receive information from the marine environment – the chemicals generated from the ecological processes or contaminants produced by human activities.
Swimming, sailing, even just building a sandcastle – the ocean benefits our physical and mental wellbeing. Curious about how a strong coastal connection helps drive marine conservation, scientists are diving in to investigate the power of blue health.
This article is part of a series, Vitamin Sea, exploring how the ocean can be enhanced by our interaction with it.
The main chemical that contributes to that distinctive sea smell is dimethyl sulphide. This volatile organic compound containing sulphur that’s present in air and water in all marine areas.
Dimethyl sulphide, along with the evaporation of salty sea spray, creates that sharp, tangy smell that’s synonymous with the coastal experience. The concentration of dimethyl sulphide depends on many biological processes in the ocean. Marine algae produce a chemical called dimethylsulfoniopropionate (DMSP) which helps regulate their internal conditions during times of environmental stress. When algae die, that DMSP is released into the surrounding water where bacteria and enzymes convert it into dimethyl sulphide.
The Moon also affects the smell of the sea because the growth of algae changes with the tides. American marine biologist Rachel Carson described the impact of moon cycle on the ocean smell in her book The Sea Around Us (1951):
…for a time each spring, the waters may become blotched with brown, jellylike masses, and the fishermen’s nets come up dripping a brown slime and containing no fish, for the herring have turned away from these waters as though in loathing of the viscid, foul-smelling algae. But in less time than passes between the full moon and the new, the spring flowering of Phaeocystis is past and the waters have cleared again.
Changing smells reflect the changes in dynamics between marine life, water, the atmosphere and human activities. The foul smell from algae indicates decomposition and anaerobic activity in the water. The smell of decay often accompanies oxygen-deprived environments where organic matter breaks down. Monitoring the olfactory signals of ecosystems, such as the concentration of dimethyl sulphide or the smell of decaying algae, can provide insights into the health of marine environments and signal potential problems like low oxygen levels or contamination.
Scientists have started to explore the impact of climate change on the sea smells. Recent research by Matthew Salter, a marine biogeochemist at Stockholm University, investigates the volatile organic compounds (gaseous chemicals) emitted by cyanobacteria and other plankton that inhabit coastlines of the Baltic Sea. His team studies how these chemicals contribute to the formation of aerosols leading to climate change.
Saving healthy smellscapes
Preserving the natural scents of the sea requires concerted efforts to reduce sewage pollution and plastic waste reaching the sea. That involves promoting sustainable fishing practices and urban development, and mitigating climate change that causes extreme weather and rising sea levels that threaten marine habitats and coastal landscapes. Oceans are becoming more acidic as more carbon dioxide enters the atmosphere.
New findings suggest that ocean acidification may affect how sea creatures detect smells, which, in turn, affects their ability to detect predators, find food and track mates.
Read more:
Oceans may become too acidic for animals to smell their way around
Melting ice caps and thawing permafrost are also releasing bacteria and other microbes that have been dormant for thousands or even millions of years. So how the sea smellscapes might change over the coming decades and centuries is unpredictable.
Meanwhile, creatives are pioneering ways to document ocean smellscapes. In the tidalectics project, Norwegian chemist Sissel Tolaas collected oceanic smells from the Caribbean and the Pacific coasts of Costa Rica, analysed the key chemicals and reproduced them. At her exhibition, she presented smells from waves to pollution to alert people about ecological change through their noses.
Kate McLean
Researcher and artist Kate Mclean creates maps to illustrate smellscapes. In Newport, a seaside city on Rhode Island in the US, she documented the ocean-based smells to build a visual-olfactory catalogue. Different colour codes represent different collective responses to smells from people who joined Mclean on a smell walk. Blue lines show ocean smells spreading across the island as they are encountered frequently by residents and visitors.
As the environment changes, documenting smellscapes of the ocean could provide insight into the state of our seas and our relationship with coastal waters. So next time you take a breath of fresh air, by the sea or otherwise, take a moment to think about scent ecology. Our relationships with smells play a crucial role in connecting us to nature and telling us more about the health of our oceans.