Tag Archives: Coral

Glowing Coral!

Did you know that some corals GLOW under ultra-violet light? Well they do! And last night some of us at A Rocha Kenya set out to see the amazing phenomenon for ourselves.


Conditions were perfect for some late-night rock pooling, so we headed out to the pools we knew had a lot of coral, and armed with torches and a small UV light. We were not disappointed! The corals glowed spectacularly, and we even saw some moray eels and a Spanish Dancer nudibranch as well!

glowing coral 1   glowing coral 2   glowing coral 3


To be truly accurate, it’s not actually the coral itself that is fluorescing (giving off light), it is the zooxanthellae living IN the coral! Tiny little algae live with coral and give it its color during the day, and some re-emit light to get spectacular displays like this. The coral and the zooxanthellae rely on each other to live: essentially, the zooxanthellae provides food and the coral provides shelter. Without that relationship, we wouldn’t have beautiful coral reefs, or nighttime displays like this!


People don’t know exactly why this “glowing coral” phenomenon happens, but there are a lot of interesting theories. One theory is that the fluorescent molecules work sort of like sunscreen!


Whatever the reason, we certainly are lucky at Mwamba that all of this is right in our own back yard.


Marine Photo of the Week

This week I stumbled across a little toby (relative of the pufferfish) which I had never seen before. It was very camouflaged against the rocks and seaweed, and even after much examination of the photos I got of it I was unable to identify which species it is (if you know please tell me!). Besides the excitement of (potentially) a new species for Watamu Marine Park, I was struck by one photo of a close up of its face how beautifully colourful and detailed it was. Pinks, blues and greens close-up, but browns and greys of seaweed from afar. A remarkable little thing.

Photo of the week

This week Bob Sluka (marine project director) was down on the coast with me (Benjo) to have various meetings and look at new directions for this field season. One area we wanted to investigate was night surveys, as this would potentially reveal a whole host of new species found on the reef, but hidden through the day. I was also keen to try my new UV torch, which we bought because of a peculiar feature of corals; under ultraviolet light proteins in their tissues glow bright colours. Apart from being stunning kaleidoscope of weird phosphorescent colours, it is also useful to look at corals under UV because it easily picks up juveniles from the dull background, an important tool for the recruitment studies I am interested in. Some theories suggest that the florescent proteins are for  protecting coral from the sun, but this has not been proven and to date we are not entirely sure why they fluoresce (see Charles Manzel for leading research in this field). During daylight my camera has been producing some really satisfying photos, but it wasn’t quite up to this challenge. Sadly the auto-focus would not latch on well and seems to have filtered out some of colours that I could see while down there. Nevertheless I managed to get a few photos which give an idea of the magical quality of corals under UV, but to see better images click here or even better come with us on a night dive!

Marine Photo(s) of the Week

Hi to all! I’m back in Kenya and feel I need to make up for my lack of communication by showing you not just one, but three photos of the week. Already I have been back out to sea, specifically taking photos of every different kind of coral I can in order to build a species list of corals for Watamu Marine Park. To identify corals reliably to species it’s necessary to look at the tiny detail and structures of the colonies, often looking at the individual coral animals (coralites) themselves. Below are three corals I have found with  close ups of the incredible patterns and structure they exhibit, at a scale most of us would never notice.




The coralites of this Goniastrea extends their fleshy body parts during the day (most corals only do this at night) creating an impression of a miniature flower garden swaying in the waves.

The coralites on the branches of this Acropora are enclosed in small cups facing upwards to the light, their food source and growing out towards it.

Gardineroseris is covered in small grooves and valleys in a complex, but ordered pattern.

Marine Photo of the Week

Incredible diversity on one small patch of reef in Watamu Marine Park. In this photo there at least 8 genra of coral all crowded and competing for sunlight. In the centre and bottom left there is Pocillopora, the bottom right is some encrusting Montipora, above this a small green patch of Galaxea. Along the top there is the winding lines of Platygyra on the left, next to a yellow branching Acropora, nestled next to a smooth brown Porites in the top right. In the middle there are two domed corals with circular coralites (pits) which are most probably Favites and Favia, although a closer look would be needed for these two. How and why all these corals are crowded together is difficult to know and as complex as any rainforest structure, with canopy Pocilloporas and Acroporas, which an understorey of creeping Monitpora and emergent Porites bursting through the structure to form smooth domes.

Marine Photo of the Week

The Convict Surgeonfish (Acanthurus triostegus) is a convict in both form and behaviour. It was presumably given the name because of its distinctive pale yellow and black stripy colouration similar to that of uniforms that criminals wore in times gone by. However, these fish are also convicts because they are the raiders of the reef. Like most Surgeonfish they are herbivores, feeding on turf algae found on the reef, but unlike many reef fish they don’t maintain territories. Instead they move in large shoals, descending and overwhelming a resident fish, rapidly eating all the algae in its territory and then moving on. They may appear to the untrained eye to be an innocent shimmering of stripes zipping around the coral heads, but for reef inhabitants they are no good hooligans!

Marine Photo of the Week

This week’s photo is the open mouth of a stunning blue Giant Clam (Tridanca maxima). These giant molluscs, related to snails, octopus and mussels, have given up traditional bivalve filter feeding on microorganisms living in the water column, but instead have developed a close relationship with their former prey. Single celled phytoplankton, a major food source for most bivalves, are resident in the clam’s flesh giving a range of striking patterns and colours, but more importantly fixing sunlight into sugar molecules through photosynthesis which the clam then feeds on. In return phytoplankton receive waste products and Carbon Dioxide from the clam which helps them grow. In addition to the corals themselves, the clam is one of many many examples of Symbiosis, or living together, seen on coral reefs where cooperation between unrelated organisms pays off and over many years ends up being a permanent new hybrid organism. It just goes to show how a little cooperation can be very useful!

Marine Photo of the Week

Allard's Anemone Fish

The photo of this week is of a beautiful Allard’s Anemone fish nestled in its anemone home. Made famous by the film Nemo, clownfish or anemone fish are a well known coral reef inhabitant, of which we have two species in Kenya along with the Skunk Anemone fish. Their ecology of living in symbiosis with an anemone is a great example of the incredible complexity and inter-reliance of coral reef ecology, where no single species can live without the others. It is this complexity which makes reefs so vulnerable to human destruction where one influence has many ripples through the entire reef community and is the challenge of marine ecologists to understand these complex interactions.

Marine Photo of the week

Flourishing Acropora near Uyombo

 As mentioned in a previous blog, the marine fieldwork has paused for a little while, but I will continue updating the blog with a marine photo of the week and little bit of information. This week the photo is of a large Acropora or table coral growing near Uyombo. Acropora is usually the most common type of coral found in all shallow, well-lit reefs around the world with its rapid growth and efficient branching pattern rapidly out-competing other benthic flora and fauna. However, the beautiful beds of shallow water Acropora are no longer as common as they should be, being highly threatened by global warming and other disturbances. Watamu nearly lost all its Acropora after the 1998 El Nino event, as did much of the Indian Ocean. It is great to see beds of coral like this one growing back to their former glory around Watamu National Park, and let’s pray that the human influences which destroyed the coral in the first place can be mitigated. 

Finishing up Marine Work

Time has really raced the last few months for the marine team. Starting in January, Joy Smith an Oceanographer from Virginia, USA, joined me (Benjo) and together we really pushed forward with data collection on the reef. However all too quickly we’ve come to the end of this year’s field season, with weather set to get windier and the sea to get rougher from April through to September during ‘kusi’ monsoon. I’m now sitting in a coffee house in Nairobi thinking about all those wonders way down on the coast and realising that none of the magic of the reef has been lost. Below are a couple of photos from the last snorkel I did around a site we call ‘the larder’. A huge shoal of trevally completely surrounded us and beautiful sweetlips swam lazily over to figure out what these strange new creatures in their home were.

A final piece of news is that nearly all the plates we put down in December are now out of the water. I say nearly, because sadly we couldn’t find one of the plates placed in Kanani, but nevertheless recovering 35 small pieces of equipment that have been sitting on a large underwater landscape for 3 months is quite successful I feel. We did the work in collaboration with Kenya Marine and Fisheries Research Institute (KEMFRI), which not only being another great contact for future work, but was a lot of fun for the three days we were zooming around the park and pulling the plates up. Juliet from KEMFRI started helping us analyse the plates looking at the major types of organisms settling. While I could see some little corals on the plates, we need to use a microscope and Juliet’s expertise for a longer period of time to get the final results of this interesting study. The plates are stored and can be analysed at any time in the future, so all the more to look forward to for the next field season!