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Summary
DescriptionCnidaria disturbing the pycnocline in Gullmarn fjord at Sämstad 3.jpg
English: Three lion's mane jellyfishes (Cyanea capillata) of different sizes and a moon jellyfish (Aurelia aurita) in Gullmarn fjord at Sämstad, Lysekil Municipality, Sweden. The jellies are disturbing the top water layer of the fjord. The photo was taken on a calm, sunny morning after a rain, so it's likely that the layer is warmer water with some freshwater added. In this case that would make a thermocline coincide with a halocline and resulting in a very thin but visible pycnocline. This difference in density and the altered refractive index is what makes the water look "oily". The jellies are quite small and young, about 5–6 cm (2.0–2.4 in) in diameter, and since they are just below the surface and stirring up the pycnocline beneath them, that would make the layer of warmer freshwater on the fjord about 6–8 cm (2.4–3.1 in) thick at the time. Some of the tentacles of the big jelly (especially top right of the bell) are dipping into the pycnocline layer, making them look fractured by the light. Most of the dots, bright and dark are daphnias and other small animals; the fjord is teeming with them.
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This is a retouched picture, which means that it has been digitally altered from its original version. Modifications: Some debris in the water, mostly flies, seeds and plant parts, have been removed.
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Three lion's mane jellyfishes (Cyanea capillata) and a moon jellyfish (Aurelia aurita) disturbing the visible pycnocline in Gullmarn fjord at Sämstad, Lysekil Municipality, Sweden.
Cnidaria disturbing the pycnocline in Gullmarn fjord at Sämstad
Image title
Lion's mane jellyfishes (Cyanea capillata) and a moon jellyfish (Aurelia aurita) in Gullmarn fjord at Sämstad, Lysekil Municipality, Sweden. The jelly medusas are still quite small, about 5–6 cm (2.0–2.4 in) in diameter.The jellies are disturbing the top water layer of the fjord. The photo was taken on a calm, sunny morning after a rain, so it's likely that the layer is warmer water with some freshwater added. In this case that would make a thermocline coincide with a halocline and resulting in a very thin but visible pycnocline. This difference in density and the altered refractive index is what makes the water look "oily".