Along the ragged coastline of the island of Eleuthera in The Bahamas, a lemon shark pup (Negaprion brevirostris) swims through the gnarled branches of a mangrove. At just six months old, the pup is fully independent, and has been since birth. It will patrol the mangrove forest’s roots and submerged branches, shielded from predators and surrounded by prey, until it reaches full maturity. After spending nearly a decade in this unique ecosystem, the young adult, like other members of its species, will venture into the reefs and open waters farther out to sea. Eventually, female lemon sharks complete their life cycle by returning to the same patch of mangroves where they were born to give birth to their own litters.
Mangrove forests are a biologically rich tangle of salt-tolerant trees—some 80 species in all—that grow in shallow tropical and sub-tropical waters around the world. Although seen by many as useless, impenetrable, insect-ridden swamps, mangrove ecosystems provide habitat for untold numbers of marine organisms, and play a critical role in coastal protection. Their intertwining roots anchor firmly in the mud and create a safe haven and nursery for far more creatures than lemon sharks. Migratory birds, juvenile fish, and shellfish also spend critical periods of their lives here. The fringe of mangrove forests along coastlines also improves water quality by filtering pollutants, and serves as an important buffer against coastal erosion—a problem that grows as sea levels rise. Recent research even demonstrates that mangroves significantly increase the alkalinity of the sea water around them, providing hope that these forests could mitigate the effects of increasing ocean acidification for nearby reefs. Despite their value, mangroves are being cleared at a staggering rate—for aquaculture, tourism, and other forms of coastal development. Experts estimate that at least half of the world’s mangroves have already been destroyed, and that we’re currently losing these valuable habitats at a rate of 1% each year. Without more thoughtful coastal development, odds are good that this shark pup will one day return to find a hotel and an eroding beach in place of the mangrove forest where it was born.
Eleuthera, The Bahamas
Shane Gross is a freelance marine conservation photojournalist originally from the prairies of central Canada. He relocated to the Bahamas in 2012 with the goal of documenting the conservation successes and the threats facing the incredible marine ecosystems found throughout the islands. Gross is most at home among sharks and rays and hopes that his work can play even a small role in helping to protect marine fauna and their habitats.
Katie Jewett is a Bay Area science writer, previously at the California Academy of Sciences and now at the Stanford Center for Ocean Solutions, where she loves learning something new about our planet every day. Previously, she spent winters in the Colorado Rockies and summers living and working on the water.