Thank you for signing up to keep in touch with the Coral Conservation Project. Pictured above, you will find your coral frame as it was few days after construction. Your personal page will allow you to see more regular updates and amazing facts about the corals and animals living on your frame. By now having all the updates on one page, seeing the progress of your frame will be much easier and convenient. If you want to satisfy your curiosity even more, you can take a look at our Marine Blog Life and videos from the Marine Lab Diary or connect with us for more information.
Here is the start of a healthy coral reef relationship!
Coral reefs are built and made up of thousands of tiny animals called coral “polyps” that can live individually (like many mushroom corals do) or in large colonies that comprise an entire reef structure. A polyp has a sac-like body and an opening, or mouth, encircled by stinging tentacles called nematocysts or cnidae (imagine an upside down jellyfish). The polyp extracts calcium and carbonate ions from seawater to build itself a hard, cup-shaped skeleton made of calcium carbonate (limestone). This limestone skeleton protects the soft, delicate body of the polyp. Coral polyps are usually nocturnal, meaning that they stay inside their skeletons during the day. At night, polyps extend their tentacles to feed. Most coral polyps have clear bodies whereas their skeletons are completely white, like human bones. Generally, their brilliant color comes from the zooxanthellae (tiny algae) living inside their tissues. Several million zooxanthellae live and produce pigments in just one square inch of coral. These pigments are visible through the clear body of the polyp and are what gives coral its beautiful color.
Looking at your frame, you will see that it is doing amazing and the corals are really growing well since the last update even after the heated months and some stormy weather. We have done some recent maintenance on all the frames which include cleaning them, removing the invasive algae and coral predators to maximize growth. In the upcoming post we will show you close-ups of your frame and the coral fragments, with some interesting facts and findings about those that are on your frame. After 6 months you will see a similar post showing once again the progress of your frame.
As you can see from the picture, your coral frame are colonized by some little, brown and green organisms called Ascidia. The species is called Didemnum molle (also known as the green barrel sea squirt or the green reef sea-squirt.) and is very common in the Indo-Pacific area. Ascidia is a filter-feeder, feeding on suspended plankton and detritus and its green color is given by the algae living in symbiosis with them, in this way the algae is protected by the predation and the Ascidia can receive energy from its little hosts. Luckily they don’t possess any threat to the corals when they are few in numbers, however they can colonize quite quickly on the frames through asexual budding, as such they are regularly removed to minimize competition with growing corals.
A fresh scar from a broken branch, the white indicate the calcium skeleton underneath that is produced by the tiny polys above year after year. Since collected fragments are picked up rather than broken down from existing colonies they often have dead sections covered with overgrowing algae and dead or damaged polyps, as such these sections are removed for faster recovery. You can already see the new polyps starting to grow along the bottom of the scar, soon the branch will regrow into its former state.
The Dascyllus aruanus, known commonly as humbug damselfish, has found in your coral frame its home. This particular fish is known by multiple common names, such as three stripe damselfish, humbug dascyllus, or black and white damselfish. They only reach an adult size of 3-4 inches (7.6-10 cm). Sporting three broad black stripes on a white body, the humbug damselfish has a zebra like appearance. The stripes run slightly off vertical through the eyes and mouth, midbody and bisecting the caudal peduncle, making it half black and half white. There are several contestants for the title of most important reef fish family, but the Damselfish are certainly one of the front-runners. Not only are there numerous species, but also many of these species are present on Maldivian reefs in prodigious numbers. The humbug damselfish that you can see in the picture is associated with isolated coral heads in sheltered inshore habitats. Like all damselfish, they can be territorial and aggressive, especially as they get older.
Tridacna crocea, commonly known as the boring clam is a species of bivalve/ mussel. This clam is native to the Indo-Pacific region and is the smallest of its family with a maximum size of 15cm/ 6 in. This clam can wildly vary in color from orange and pink to deep blue and purple. The soft animal inside is protected by its hard shell which can burrow into the sand or into the substrate of corals (like in your case). And interesting fact is that clams actually have algae living inside of them which through photosynthesis create their color as well as provide food to the clam. Besides living in a symbiosis with algae, clams are filter feeders and feed on small suspended particles like plankton.
Do you know that even under the water we can found cobwebs? The responsible invertebrate responsible for this mesh is not a spider, but rather a gastropod mollusk called Ceraesignum maximum. As all Vermeidae, this mollusk species is sessile and houses themselves within tubular shells. They are common dwellers of shallow water in coral reefs and rocky shores. These nets are called mucus nets that can be expand around the individual up to 10 cm in diameter. Under wave action and currents allow suspended particles to be trapped in these sticky nets that are withdrawn at regular intervals for consumption.
This is your 6 month frame progress update. Your frame is doing fantastic!
Looking at your frame, we can see lots of new growth, especially of the acropora corals (the branching & fast growing corals). We can see some of the corals are competing for space, which is a good problem to have, it means your frame is thriving. We can also see that your frame is contributing to the overall health of the coral ecosystem. We see lots of life such as little fish, crabs, worms and mollusks around your frame. Overall your frame has survived the warm months of March, April and May just fine, unfortunately some of the other frames in our colony weren’t so lucky.
Over the following months we will continue with maintenance to keep harmful algae and predators off your frame and to give your frame the best chance for successful growth.
Looking at this species of Acropora on your frame, you will notice the white tips on the branches. When corals are stressed by changes in water conditions such as temperature, light intensity, or nutrients, they expel the symbiotic algae called Zooxanthellae, living inside their tissues, causing them to turn completely white, this is also known as coral bleaching. When a coral bleaches, it is not dead yet, but may soon starve if conditions persist, since the animals inside rely on this algae for its energy. If their stress levels are not severe, corals may recover. If the algae loss is prolonged and the stress continues, coral eventually dies. Here in the Maldives, the peak temperature is around March – June, when we also see some of the corals turn white, usually their colors return soon after if conditions don’t persist.
We would like to give some information about this colony of Acropora digitifera that lives on your coral frame. This species forms digitate colonies; the branches may be 1 cm in diameter and up to 10 cm long. This species strongly prefers shallow water. It is usually cream or light brown in color with blue branch tips, but can also be brown with purple tips. It is common near reef crests’ as it prefers strong water movement and it is very common in the Maldives. The most important known threat is the reduction of coral reef habitat due to bleaching, disease and predation. However, it seems to be strong enough to resist to habitat loss more than other species of corals. However, since the current situation with multiple stresses (mainly rising temperature of the ocean) acting simultaneously the species is considered Near Threatened by the International Union for Conservation of Nature (IUCN).
Coral reefs for the most part appear to be static environments, despite the presence of ever busy fish, this is because most of the activities happening within corals are invisible to our eyes. In fact, coral reefs are a dynamic environment where every cm2 may hide beauty or a fight for survival! Among the invisible, corals are surely the most active, by building the amazing structure which allow us to see paradise tropical islands! However, they are continuously fighting for the survival, against predators, disease and environmental changes, and even between them. They are supplied with microscopic needles and venomous tentacles to kill any other corals which may try to steal space and light! Here you will see two different species of Acropora competing for the same space
We have noticed that some fragments such as this one pictured have some damage and as a result they die completely. This happens from time to time that fragments might receive very high stress levels due to increased water temperatures and they lose the symbiotic algae Zooxanthellae that they need to survive. Sometimes corals also need to compete with invasive algae that grow over the polyps and when this happens they will also die off. During the maintenance these pieces of dead coral is usually removed while the live part remains attached.
How do corals grow bigger? Coral reefs are mainly built by stony or hard corals, together with their endosymbiotic algae (algae living into the corals), zooxanthellae. To give you some information on how the calcification process works. The main elements needed to build the skeleton are Ca2+ (Calcium ions) and DIC (Dissolved Inorganic Carbon). Both these elements are transported into a specific area of the coral called the “calcifying region”, which is situated under each single polyp. Here, the calcium carbonate (CaCO3) is formed throughout a chemical reaction. Finally, the calcium carbonate (or technically crystals of aragonite) is deposited to form the skeleton. The process involves the polyp’s cells and the zooxanthellae and by the mutualistic work of these two counterparts the skeleton is formed. However, if for any reasons (i.e. high temperature) one of the two parts is not working properly the process stops and the coral may die.
We regularly clean the iron frame from algae and other organisms which may slow down the coral fragments growth by competition. Furthermore, we remove the dead fragments and we fix new one taken from the reef. As it is shown in the picture, we attached a couple of new branching Acropora fragments, which were found already broken on the shallow reef of Thudufushi. While the picture was taken, a couple of fish appear just in front of the camera, in the exact moment of shooting. Thanks to its curiosity, we can appreciate the amazing pattern of colors of this Thalassoma lunare or Moon Wrasse.
