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Image 1: A John Dory (Zeus faber) exhibiting biofluorescence from Atlantic waters beneath Derrynane, Co. Kerry, Ireland. Containing fluorescent proteins the John Dory absorbs, transforms and reemits light giving off this incredible display. Image 2: (slide to reveal) The same John Dory photographed in white light showing its natural colouration and Image 3: Another view of the fluorescing John Dory.
IMAGES: VINCENT HYLAND

Photographs reveal the hidden light of Ireland's underwater marine life
Very little is known about the hidden light that emits from a select few of Ireland's underwater marine inshore flora and fauna. The phenomenon occurs when certain marine plants and animals that contain fluorescent proteins absorb, transfer and reemit light in a colourful display known as marine fluorescence. Quite a lot of research has been carried out in this area particularly in the tropics amongst coral reefs and the communities of fish that live in and around these habitats. In 2015 I had already photographed bioluminescence (the biochemical emission of light by plankton) at Derrynane and my curiosity led me to believe that other underwater marine animals must emit light too. Then during one dark September night while carrying a 'blue' light on a night dive I noticed that as I directed the beam of my torch on cup corals that they glowed back. My curiosity was awakened. I carried out some research and found that the majority of the literature was from the aforementioned tropical seas. There was nothing relating to temperate marine oceans. Like an excited child I could not wait to investigate and before long I got my hands on a set of blue lights and yellow barrier filters so that I could study and photograph marine fluorescence in more detail. I did not know what to expect nor did I ever imagine that what I was about to witness was simply incredible.

Video 1:
Always on the move this Red Mullet took me on a journey of discovery as it made its way over the bottom sediment in its search for food. In part 2 a fluorescent anemone is seen feeding. 
IMAGE: VINCENT HYLAND

By the time I got into the water to try out the new setup the air and water temperatures had dropped significantly. I would not have much time to explore. Now into late October 2015, storms were imminent and with only a semi dry wetsuit to keep me warm I took the plunge. The eeriness of night time diving is a great leveller of the senses. Most of my initial forays were just off the beaches at Derrynane, Rath and Glanbeg. In order to successfully capture fluorescence you first have to scout the area using white light. Not knowing what did or did not fluoresce meant that I had to scan everything. The process was to shine the white light on the subject. If it was stationary then no issue, if the current meant that you also had to hold yourself in place then it became a little more difficult. If the subject swayed it brought additional challenges and if the subject moved then I found myself having to follow it until it lay down or stopped in mid water. Whatever situation arose the next step was to place a yellow barrier filter over the camera housing lens, pull down the corresponding yellow barrier filter over my dive mask, turn off the white light and then turn on the concentrated beam of the blue light. The transfer from white light to blue light for photographic purposes took about thirty seconds. Nine times out of ten the creature I was trying to aim at disappeared or got covered up by seaweed and made it difficult for me to find it again.  Some nights it was disappointing. Maybe I was looking in the wrong place, or maybe I was not doing the procedure right or perhaps not a lot fluoresces under the sea in Ireland. Undeterred I kept on going. I did notice however that a good portion of marine algae and to my surprise seagrass exhibited fluorescence. Most of the light was in the red spectrum. Sometimes I would just travel through kelp beds and observe the amazing colour display as I passed by. It really is addictive you know!

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Image 4:
Like a writhing snake goddess the tentacles of a Daisy anemone exhibit fluorescence.
IMAGES: VINCENT HYLAND

By the time November came I began to perfect the technique. The sea remained calm and allowed me most of the month exploring, photographing, searching and learning. By heck it sure was cold! By the time the first of the winter storms broke I had managed to capture fluorescence in anemones, prawns, fish and other temperate ocean marine life. In the years that followed I kept on making new discoveries and just last night (21st September, 2021) on the eve of the northern hemisphere Autumn Equinox I managed to photograph a John Dory fish displaying fluorescence. As before I did not know whether this particular fish was going to fluoresce so imagine my surprise at having made this discovery. I was elated (and still am). The first and last time I had encountered this incredibly weird looking fish was back in the year 2000. That was also on a night dive and such was that encounter that it compelled me to make a short film called 'Ghostfish' where I  wrote a poem, composed and performed a soundtrack and narrated to accompany the video.  Twenty one years later there it was; another John Dory, one of the most cooperative subjects I have ever come across. It literally glued itself to my camera, such was its attraction to my white light and blue lights. 

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Image 5:
Cup corals, anemones and a variety of marine life displaying fluorescence in the red, orange and green spectrum.
IMAGE: VINCENT HYLAND

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Image 6:
Common Squat Lobster, encrusting algae, star ascidians and anemones fluorescing in a wonderful array of colours.
IMAGE: VINCENT HYLAND

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Image 7:
A pair of fluorescing Velvet Swimming crabs in a pre-mating hug.
IMAGE: VINCENT HYLAND

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Image 7:
certainly was not expecting to see a northern prawn fluorescing.
IMAGE: VINCENT HYLAND

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Image 8:
A wonderful subject - a fluorescing snakelocks anemone seen feeding.
IMAGE: VINCENT HYLAND

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Image 9:
Red spectrum fluorescence seen in this anemone
IMAGE: VINCENT HYLAND

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Image 10:
Sea grass displaying fluorescence
IMAGE: VINCENT HYLAND

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Image 11:
fluorescent Strawberry anemone. I entered this image in the National Geographic underwater photographer of the year 2017. This was the first year that a fluorescence image took the top award. The winning image was taken by  Jim Obester. It was nice to get a mention in the Nightsea blog write-up written about the awards afterwards

Vincent Hyland lives in Caherdaniel, Co. Kerry. He is an avid environmentalist and underwater explorer and has filmed marine life from as far away as Antarctica, Galapagos to Africa and home. In the past decade he has devoted his time to documenting the biodiversity of Derrynane for his forthcoming book Wild Derrynane - a 400 page natural history detailing the coastal land and underwater marine biodiversity of the area. His outdoor classrooms are a big hit having been attended by thousands. He is a passionate techhead, artist and musician.