Gulf of Guinea

Let’s travel to the eastern side of the Atlantic Ocean, right off the coast of Africa. Between Cape López, near the Equator, and Cape Palmas lies a body of water known as the Gulf of Guinea.

The Volta River and the third largest river in Africa, the Niger River, are the major rivers that feed into the Gulf of Guinea. Because of the runoff from these two rivers, and the high amounts of rain along West Africa, the gulf’s water is lower in salinity than other parts of the ocean. This warm water is separated from deeper, colder, saltier water by a shallow thermocline.

A thermocline is a thin, distinct layer in a body of water that marks when the temperature of the water rapidly changes with depth. In the ocean, it separates the upper mixed layer near the surface and the deep, calm water below. Thermoclines exist in the atmosphere as well.

Off the coast of Guinea and Côte d’Ivoire, a seasonal coastal upwelling forms in the gulf. An upwelling occurs when cold, nutrient-rich water from the deep is brought up to the surface water. This nutrient-rich water creates a boom of activity that attracts organisms from every level of the food chain, including fish, birds, and mammals. When the nutrients are depleted, the organisms move on.

The Gulf of Guinea has been nominated as a Hope Spot. The beaches around the gulf contain prime nesting sites for leatherback sea turtles, which are a threatened species. Sea turtles grow for many years before they reach sexual maturity, and the process of reproduction can be fatal to females. Newly hatched sea turtles have a high mortality rate because of predation before they reach the ocean and from human activity. It’s extremely important to protect these nesting sites.

Within the Gulf of Guinea lies the island nation of São Tomé and Príncipe, which contains vital habitat for humpback whales, African manatees, dolphins, and soft corals. Humpback whales are considered endangered by the IUCN Red List their populations are threatened by whalers and by getting struck by cruise liners and cargo ships. African manatees are classified as vulnerable.

The Niger River is being explored for oil and gas mining, which could have a serious impact on the Gulf of Guinea. Luckily, non-government organizations (NGOs) have been working hard with both government and international partners to develop green practices to extract those natural resources. The NGOs have also been developing full-scale wildlife law enforcement programs to protect the gulf and its wildlife.

This is definitely a cool Hope Spot and I wish them the best of luck. If you travel to any of the beaches containing turtle nesting sites, see if there are any volunteer programs you can join. I know in the US there are volunteer programs that help get the baby sea turtles into the water. May not be the ideal vacation plan, but it’ll be something memorable to share with your friends and family!

Sources:
https://mission-blue.org/hope-spots/
https://www.britannica.com/place/Gulf-of-Guinea

Doctorfish

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Osteichthyes
Order: Perciformes
Family: Acanthuridae
Genus: Acanthurus
Species: Acanthurus chirurgus

Last time on Doctor Who, the Doctor was mortally wounded and forced to regenerate…again. This time, though, to everyone’s surprise and horror, the Doctor turned into a fish. And not just any fish, but the tropical surgeonfish known as the Doctorfish—bum bum buuuuuuuuuuuum!

For those of you who don’t know, I’m a giant nerd, and I laughed way too hard when I realized that I could combine Acanthurus chirurgus with Doctor Who. I have no shame—most of the time.

Anyways, the Doctorfish is a type of surgeon fish that inhabits coral reef areas and can be commonly found in Florida, Bahamas, and the Caribbean. They can also be found in the waters of the Gulf of Mexico, north to Massachusetts, south to Brazil, your neighbors’ exotic aquarium, and the tropical waters of West Africa.

Color is not always an easy way to identify these Doctorfish because they can range from bluish gray to dark brown, and they can pale or darken dramatically between individuals. The major way to identify them while diving is by looking at the body; all doctorfish have 10‒12 vertical bars between their head and their tail. They also have distinct markings around their eyes, almost like flashy eye make-up.

Acanthurus chirurgus are herbivores that feed on algae, and they even have special teeth that allow them to pick off the algae growing in the sand, in rocky areas, and even on coral. In fact, these guys are really important to reef health because they can consume the algae that grow on coral, which would otherwise smoother the coral and their best friends, the zooxanthellae.

The origin of their common name is pretty cool. A. chirurgus have spines on either side of their caudal peduncle, or the base of their tail, that were discovered to be really sharp like a scalpel that doctors use. When feeling defensive, surgeonfish will use those spines as weapons by slashing their tails side to side at their aggressors.

Typically, Doctorfish will keep their distance from divers and will try to stay away if approached. However, people handling these fish can get serious injuries which are often quite painful and can lead to serious infection, especially since there is a crazy amount of bacteria and viruses in a single drop of water! So please be careful when diving with or handling doctorfish!

They are a common fish species found in private aquariums, and while they are not considered to be at risk of becoming endangered, you should still be aware of how they are caught and sold before purchasing individuals for your aquarium.

The doctorfish was one of the fish species I had to learn to identify for my Coral Reef Ecology class in college. I’ve seen them a handful of times when diving around reefs, and I’ve even watched them eating the algae from the coral, which was pretty cool to witness. I’ve read that you can eat Doctorfish, but I won’t try that because of the slight chance of getting ciguatera poisoning—which I’ll save for another ramble!

Sources and cool links:
Reef Fish Identification: Florida Caribbean Bahamas 4th ed. By Paul Humann and Ned DeLoach
http://species-identification.org/species.php?species_group=caribbean_diving_guide&menuentry=soorten&id=209&tab=beschrijving
https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/acanthurus-chirurgus/
https://www.iucnredlist.org/species/177982/1510626
https://www.fishbase.de/summary/943