Coral Reefs
I slowly made my way down the Yasawas, stopping at a couple resorts along the way back to the main island. It is impossible to capture how stunning it is to swim out from shore and be surrounded by yards of coral reefs in crystal clear waters.
Although corals can grow in a variety of environments, most coral reefs are found between 30°N and 30°S latitudes. Corals are small animals that capture and eat plankton using stinging cells, similar to jellyfish. However, they also host a type of symbiotic plankton called dinoflagellates. These dinoflagellates perform photosynthesis and produce sugars that corals use for energy to grow, build, and survive. In return, corals provide the dinoflagellates with a safe place to live.
A single coral structure contains hundreds of genetically identical individuals living together as a colony. This cooperative structure allows them to sustain themselves and build the protective coral skeleton that shelters the entire colony. Corals require abundant sunlight and nutrient-poor water to thrive. When nutrient levels rise (particularly nitrogen, phosphorus, potassium, and iron), algae can flourish, overgrow the coral, and block the sunlight they depend on for survival.

coral reefs stretching forever
The beautiful colors of coral reefs come from the dinoflagellates living within them. When ocean temperatures rise too high, the chloroplasts in these organisms become stressed and release oxygen. This oxygen damages the coral’s cells, and the coral expels the dinoflagellates for behaving badly. This process is known as coral bleaching, and such events are becoming more common as ocean temperatures continue to rise in these regions.

Blackback Butterflyfish with corals, Cauliflower Coral, Black-axil Chromises
If the water cools down in time, corals may allow the dinoflagellates to return. However, if the water remains too warm for too long, the corals can become permanently bleached. This is because corals obtain up to 90% of their energy from their symbiotic plankton and often die when that energy source is lost.

Bicolor Blenny, Fiji Tomato Clownfish, Moorish Idol
Coral reefs cover less than 1% of the ocean floor, yet they are among the most important ecosystems in the ocean because they serve as nurseries for many species. They provide shelter and protection where young organisms can hide and grow until they are large enough to fend for themselves.

Orangestripe Triggerfish, Bridled Monocle Bream
Corals are considered to be foundation species, because the entire coral reef ecosystem wouldn’t exist without their skeletons. These animals create an area that allows all these other organisms to thrive.

Blackspotted Puffer, Specklefin Grouper, Longnose Filefish
The corals in these photos are part of a Marine Protected Area. In this case, this means that people cannot fish or remove species from the area. As fish and other organisms mature within the MPA, they gradually move into surrounding waters, where they can help repopulate other regions or become part of the food web for humans and other animals. Marine Protected Areas allow organisms, especially fish, to grow large enough to reproduce and sustain future generations.

Titan Triggerfish, Bushy Feather Star, Oriental Sweetlips
Invertebrates
As always, I went out looking for nudibranchs, and although there weren’t very many, I did manage to find a couple hiding between the corals.

Pustulose Wart Slug, Blue Linckia, Krempf’s Phyllidiopsis
Giants clams of all kinds continue to be my other favorite invertebrate find. The patterns on their mantles are intricately colored and vary dramatically between individuals.

Gigas Giant Clam, Fluted Giant Clam, Gigas Giant Clam
Muck Dive
I had heard rumors of some tiny nudibranchs down in the sandy bottoms, so I signed myself up for a muck dive. This is basically looking through sediment for weird, camouflaged organisms. I didn’t find any nudibranchs unfortunately, but I did see transparent shrimp and this tiny, patterned anemone attached to a blade of seaweed.

Sarasvati Anemone Shrimp, Swimming Anemone, Banana Coral
The most ridiculous muck dive find was a giant yellow sea cucumber that was over two feet long. Sea cucumbers feed on detritus (poop and decaying organic matter) from the ocean floor. They ingest sand, digest the organic material within it, and then get rid of the remaining sand out of their back end. Nearby was evidence of its recent activity, a large mound of sandy poop that was at least a foot across.

Herrmann’s Sea Cucumber (over 2 ft long), giant pile of sea cucumber poop (1 ft across)






























































































