This blog post was written by Anna Smith, an Ocean Conservancy intern working with the Ocean Acidification program for the month of May 2018. Anna is a senior in high school and is looking forward to studying Environmental Sciences in college.
Believe it or not, fifteen years ago today, everyone’s favorite clownfish had his big debut—our lovely friend Nemo! While the spotlight was on Nemo once again a couple years ago with his role in Disney-Pixar’s Finding Dory, we’re checking in with Nemo today to see how he’s doing, fifteen years after his first Hollywood appearance.
Sadly, Nemo and his friends are facing a reality not quite as uplifting as it may appear on-screen. Many of the difficulties that clownfish and anemonefish are experiencing have to do with the environmental threats affecting their homes, their host anemones. In recent years, large-scale coral bleaching events have resulted in detrimental impacts on coral reef communities and anemones around the world. Stressors including rising sea temperatures, ocean acidification and pollution have driven this coral bleaching, a process that involves anemones expelling the zooxanthellae that provide them with food and their beautiful coloration. And since clownfish depend on anemones for housing and protection, that’s a big problem for both corals and clownfish alike.
Research has shown that fish associated with bleached anemones suffer chronic stress, and high levels of cortisol—a stress hormone—have been detected in their blood. At the same time, this stress response has been linked to a drop in reproductive hormones in male and female clownfish; one study showed a 73% decrease in fertility among clownfish reacting to bleached anemones. In addition, clownfish reproduce in only a small temperature range and warming waters can have fatal effects on their eggs. Not only does coral bleaching stress our little friends out and deter reproduction, but the mere loss of habitat that follows makes it difficult for them to survive.