Archives for June 2019

By Raquel Gilliland, SOC Education/Outreach Intern

This Creature Feature is all about the beloved manatee, a large aquatic mammal that is part of the taxonomic order Sirenia. The word Sirenia comes from Greek mythology wherein the sailors who first discovered manatees mistook them for sirens or mermaids because of their long bodies and large tails.

Within the order Sirenia there are two taxonomic families, the Dugongidae which is comprised of only one species, Dugong dugon, and the Trichechidae which consists of three species of manatees: the Amazonian Manatee (Trichechus inunguis), the African Manatee (Trichechus senegalensis), and the West Indian Manatee (Trichechus manatus) which consists of two subspecies, the Antillean manatee and the Florida manatee.

Manatees can grow up to 4m (13 ft) long and weigh as much as 590kg (1,300lb). They are sometimes referred to as “sea cows” because of their docile behavior and slow grazing on aquatic plants. Manatees are mainly herbivorous (plant-eating) creatures and their mouths are specially shaped with a split upper lip that allows them to move the left and right side independently for more efficient grazing. Manatees eat around 10-15% of their body mass daily in plants. They use their front flippers to help dig up plants and roots and to move the plants to their mouths. They also use their front flippers and large tails for swimming slowly at an average speed of 3-5mph but can reach speeds of 20mph in short bursts, usually as flight response from danger or during a mating herd formation. They are usually observed grazing, resting on the bottom, or nursing their young. As mammals, they must surface to breathe about every five minutes but can hold their breath up to 20 minutes especially while resting. Additionally, manatees have live birth after a gestation period of about one year, after which a calf is dependent on their mother for 1-2years. Manatees reach sexual maturity at about five years of age making their reproductive rate relatively slow.

Manatees face many threats such as cold stress, boat strikes, poaching, and diseases, with the greatest threats being human-caused. The most frequent threat to the West Indian manatee is boat collisions and disease from toxic algae blooms, followed by ingestion and entanglement with fishing hooks, monofilament, ghost nets, and crab trap lines. Globally, habitat degradation due to diminishing seagrass beds and coastal development is also an ever-present threat to manatees. The African manatee’s largest threat stems from accidental capture as bycatch in fishing nets and poaching. All three species of manatees are listed as vulnerable on the IUNC Red List of Threatened and Endangered Species.

The Sea of Change Foundation supports manatee research and conservation in partnership with the African Marine Mammal Conservation Organization (AMMCO) in Cameroon, central Africa. With the Sea of Change Foundation’s support, AMMCO is improving local knowledge and awareness about the African manatee and other aquatic megafauna in Cameroon. The project trains fisherman and law enforcement in the area of Lake Ossa and the Northern Coast of Cameroon to document any sightings of manatees and take special note of manatee mortality. A public outreach campaign to educate the local community about plastic waste and the importance of protecting manatees is also part of AMMCO’s conservation project. You can learn more about and help support the Sea of Change Foundation’s work in conservation around the world, here.

By Raquel Gilliland, SOC Education/Outreach Intern

Welcome to another Creature Feature, where we introduce you to a new and fascinating animal. Today we’re learning about red lionfish (Pterois volitans). These fish can be identified from their red, white, and black stripes that serve as a warning coloration to other animals about their venomous spines. A puncture from the spines along their dorsal and pectoral fins that can cause extreme pain to humans and even death in marine animals. Lionfish belong to the family Scorpianidae which includes hundreds of species of fish that all have sharp spines that secrete venomous mucus.

Lionfish are native to the indo-pacific region but have found their way into the Caribbean and along the east coast of the United States, becoming a problematic invasive species. An invasive species is one that is not native to a specific ecosystem and has a tendency to spread to a degree believed to cause damage to the environment or our human economy and health. How can one fish cause so many problems? First, lionfish have an extremely high fecundity rate, meaning they reproduce often and in large quantities. Lionfish reach sexual maturity after just one year, and one female lionfish can produce two egg sacks every four days with each egg sack containing up to 15,000 eggs. The result can be two million eggs per female per year. These egg sacks can also float along the surface of the water for hundreds of miles, dependent on currents, increasing the geographic reach and range of the lionfish invasion in the Atlantic. Not all eggs survive, and not all juveniles mature to adulthood. But the ones that do can grow up to 47 cm (18.5 in) in length! As adults, these fish eat any other fish that they can fit in their mouths and can eat up to 90% of their body weight every day. Lionfish have also been found in mangrove systems, which act as a nursery for the young of many coral reef fishes, including economically important species such as groupers and snappers.

Secondly, lionfish have no natural predators in the Atlantic Ocean, making them virtually indestructible. However, there is hope with humans as the predators. As lionfish took over dive sites and became more noticeable, divers discovered they could spear a lionfish quite easily, as they do not swim away from divers. Today, a small sling spear is the most popular form of harvesting lionfish at collecting derbies across the Caribbean, Bahamas, and Florida. Soon, the culinary world took note of the new opportunity and found that lionfish is a white, flaky, delicate fish excellent for gourmet dishes. Because it is invasive in the Atlantic, it is one of the most sustainable seafood choices for consumers.

Our coral reefs are complex systems, where each species has a specific role to play. Just as lionfish are important to a stable reef system in their native Indo-Pacific oceans, newly introduced species have the potential to wreak havoc when introduced to a new ecosystem. One of our priorities here at Sea of Change Foundation is to work on the conservation and resilience of reef ecosystems, and we encourage divers in the Atlantic to participate in their local lionfish derby and stay up-to-date with regulations and policies on how to prevent the spread of invasive species.