Kane’ohe Bay Marine Life
A Healthy and Unique Marine Ecosystem
Kane’ohe Bay is a perfect habitat for a wide variety of marine life. Its calm, protected waters provide just the right conditions for coral reefs to grow, which in turn provides the habitat for creatures great and small, from the tiniest reef fish to giant sea turtles and manta rays.
Because of how remote the Hawaiian Islands are, roughly 25% of all marine species that we have here are considered endemic to Hawai’i, meaning they do not exist anywhere else in the world. Everything that lives here must have been able to either swim, drift, or hitch a ride somehow for at least 3000 miles before finding the warm, tropical waters inside Hawai’i’s reefs.
But there is still a spectacular amount of marine life that has found its way here, some that are just passing through during their migrations, and others that live their whole lives here in the bay. Their home is supported by one of the tiniest animals in the ocean that many people don’t even realize is an animal: coral!
Coral Reef: The Foundation of the Tropical Marine Ecosystem
Many people don’t realize that coral is actually an animal! A coral reef is actually a vast community of millions of tiny animals called polyps. Coral polyps are very fragile, delicate animals. They require the right temperature and the right amount of sunlight in order to survive. Fortunately Kane’ohe Bay provides just the right conditions.
All life in this ecosystem relies on the coral reef in order to survive. Coral provides shelter and food for many of the animals that live here. Coral is at the bottom of the pyramid, the very foundation of the entire ecosystem. If the coral goes away, so will all the other animals.
There are many different species of coral which get classified into two basic categories: hard corals and soft corals. All of the coral species that live in Hawai’i are hard corals, and they grow an exoskeleton, which basically means their bones are on the outside.
This hard mineral exoskeleton protects the coral polyps within, but even so, corals are very fragile and easily broken, damaged, and destroyed by human impact. One footstep can kill hundreds of years of coral growth. And even the chemicals found in many common sunscreens have been found to be toxic to coral.
So when you kayak and snorkel here it is critically important to wear reef safe sun protection and avoid all contact with coral at all costs. Even if it looks like rock, it is a living animal that all life on the reef depends on!
Formation of a Coral Reef
Coral polyps need very specific conditions in order to grow. The right temperature and amount of sunlight are crucial. Once the polyp has drifted upon a place with the right depth, visibility, sunlight, and temperature, it can grow and reproduce.
Coral reefs grow over decades, generations, even millennia. A coral reef can be tens and even hundreds of thousands of years old. In Hawai’i there are possibly 70 or more species of coral, roughly 25% of which are endemic, found nowhere else in the world by Hawai’i!
Corals reproduce either by spawning, or by producing clones that produce clones and so on. They grow on top of each other and compete with each other for space. They grow upwards and outwards, trying to get closer to their source of sunlight. The spawning of coral polyps is also the food of many other animals on the reef, from the smallest reef fish to giant manta rays!
Many corals are accompanied by a special kind of algae called zooxanthellae, which grows within the coral itself. This algae is what gives the coral its color. The algae depends on photosynthesis for energy, which produces oxygen and carbohydrates. And while corals can also feed on zooplankton, the biproducts of this algae’s photosynthesis provide the majority of the food and energy source for many of our coral species.
The phenomenon known as “coral bleaching” occurs when even the slightest of changes in water temperature or lighting or chemical balance result in the expulsion of the zooxanthellae from the coral. Once that algae no longer lives in the coral, it loses its color and becomes bone white, hence the term “bleaching.” This also means the coral loses the vast majority of its energy source, which is why coral bleaching events are deadly to the coral.
Marine Life That Need the Coral Reef
Honu: The Hawaiian Green Sea Turtle
The Hawaiian Green Sea Turtle can be found all over the Hawaiian Islands. They especially like to take up residence in shallow, reef protected bays, and especially in areas with thriving coral reefs. Kane’ohe Bay is home to an astonishing sea turtle population.
Once endangered due to overfishing and loss of habitat and nesting grounds, the Honu has made a great comeback. It is no longer considered endangered, but it is still a state and federally protected species.
These sea turtles also very much depend on coral reefs as a source of food and shelter. By the time they are considered adults (roughly 20-30 years old!) Honu are almost entirely vegetarian, eating mostly algae and seaweed. But younger turtles also enjoy jellyfish, Portuguese Man-o-War, and larval crustaceans. Who doesn’t, am I right?!
These turtles will literally live and sleep within the coral reef formations. A resting Honu can stay under water without coming up for air for over 2 hours. The adult females will leave the safety of their reef home when it’s time to lay their eggs, at which time they will migrate back to the same beach they were hatched on, which in most cases is over 1000 miles away in the Northwest Hawaiian Island Chain! How these turtles navigate and find their way back to their nesting grounds is still somewhat of a mystery.
If you are lucky enough to see one, please observe from a respectful distance. Attempting to touch, feed, catch, harm, or otherwise interefere with sea turtles is illegal. We are guests in their home, and our goal is for our presence and behavior to not influence theirs.