Finding Nemo: The Problem Once You’ve Found Him
Due to the gigantic success of the Disney Pixar film Finding Nemo in 2003, the sales for Amphiprion ocellaris (A. ocellaris), the common clownfish, and Amphiprion percula (A. percula), the orange clownfish, skyrocketed. These two species saw a huge increase in popularity as they extremely similar, the only difference between them visually is the number of spines on the dorsal fin, with A. percula having ten and A. ocellaris having eleven. Furthermore, The other visual aid to tell the species apart is the thickness of the black lining the fins and white markings.
These animals live in small groups and within this group there is a size hierarchy. The group is made up of one breeding pair and up to 4 ‘non-breeders’. They are all born male. It is usually the larger individual that makes the irreversible change to female in order to become the most dominant in the group. The second largest becomes the dominant male. The other individuals move up the hierarchy if the female dies, with the dominant male changing into a female and the next largest taking the role of the dominant male. These beautiful animals are well known to have a symbiotic relationship with Anemones, in particular they have mutualism. Anemones are visually striking due to their colourful tentacles, however these are loaded with a neurotoxin in order to paralyse prey. Clownfish have developed a way in which to protect themselves from this, and that is due to mucus. There are many ways in which both these organisms help one another. For example, the clownfish use the anemone as protection from predictors, likewise for the anemone the clownfish ward away any polyp-eating fish. Also, it is understood that the clownfish attract the anemone’s prey and the clownfish are able to feed on any scraps. The final example is that the clownfish takes care of the anemone by cleaning any parasites that are found and by swimming in the anemone to increase circulation.
Effect of Climate Change
Just like many other species both the clownfish and the anemone are being drastically affected by climate change. This materialises in the shape of anemone bleaching which is very similar to coral bleaching. The anemone is exposed to too much light and this causes the algae that inhabitats it to be expelled. This is another symbiotic relationship that the anemone creates with the algae in the form of carbon dioxide being produced for the algae and oxygen being produced for the anemone. This lack of algae has a direct effect to the anemone because it loses vital nutrients and chemicals in order to stay healthy and in the extreme to stay alive.
This has a surprising effect on the clownfish, it is causing them not to lay eggs due to stress. Investigations have been done into this subject and it was seen through blood samples that when they inhabit a bleached anemone there was an increase in the level of a stress hormone and a sharp decrease in sex hormones. With the increase in the stress hormone, cortisol, this had a negative influence in the amount of eggs that were being laid.
Tropical Fish Trade
With the film Finding Nemo being such a great success it instantly put a huge demand in place for clownfish and this paved the way for companies and private sellers to meet that demand and this is having a devastating effect on their population due to the fact that 90% of the animals being sold are taken from the wild. This sudden increase also proved challenging as there were very few captive breeding programs in place in order to meet demand. Captive breeding programmes were introduced in order to protect numbers in the wild, however, it is still unclear of the actual amount still thought to be taken from the wild.
Looking to the Future
Conservation efforts, such as the Saving Nemo Conservation Fund, were put in place to restore the depleting populations. Due to the success of the captive breeding they were able to help replenish the wild populations but also able to start securing the demands of the use of this species as a pet through the captive programmes instead of using the wild populations. The same success can not be seen however in Nemo’s film companion Dory. Dory is a Paracanthurus hepatus more commonly known as a blue tang. Similar increased popularity has been seen in this species. However, this species is not able to be successfully bred in captivity along with many other tropical fish and this is a cause for concern.