Written by Manu madhavan
Edited by Sofia Perez
Countless flora and fauna call coral reefs home, making this ecosystem one of the most essential and diverse on the planet. However, coral reefs face almost as many threats as a result of pollution, overfishing, and climate change. The parrotfish is a key organism in maintaining the stability and health of coral reef ecosystems. Parrotfishes are brightly coloured tropical creatures that can live up to seven years and spend the majority of their time eating algae from coral reefs. This almost constant eating helps to clean the reef, allowing the corals to stay healthy and thrive.
Over 95 different fish species are collectively referred to as parrotfishes, which is a family (Scaridae) or subfamily (Scarinae) of the wrasses [1]. The Indo-Pacific region has the highest species richness for this group, with roughly 95 species. They can have a significant impact on bioerosion and can be found in seagrass beds, rocky beaches, and coral reefs [2]. The digestive system of parrotfishes, which includes more teeth inside their throats, breaks down coral bits into the white sands that make South Pacific beaches famous. This bioerosion process, helps control algae populations while also creating new surfaces for baby corals to attach to and grow on. But how much sand can a parrotfish generate? Surely it can’t be enough to create entire beaches? Consider again. According to scientists, a single Chlorurus gibbus parrotfish can poop out over 2,000 pounds of sand per year! (https://www.nature.org/en-us/get-involved/how-to-help/animals-we-protect/parrotfish/) [2].
By eating algae that can overgrow and smother coral and prevent it from growing and thriving, these vibrant and distinctive fish are essential in maintaining the equilibrium of coral reefs. The over-exploitation of parrotfish poses a significant threat to coral reef ecosystems and the species that depend on them. A keystone species in coral reef ecosystems, parrotfish help keep coral reefs healthy and diverse by eating algae that could otherwise overgrow and suffocate coral, allowing the coral to grow and thrive.
Fig 2. Parrotfish hunting
Fig 3. Several Reef Fish Species Collected by Fishers Including Parrotfish
Overfishing of parrotfish populations is one of the stressors that can upset the harmony of coral reef ecosystems, causing an increase in algae and a loss in coral health. Many reefs experienced a dramatic decline in coral cover, accompanied by an increase in fleshy macroalgae. Once spread, some species of macroalgae can inhibit coral growth, decrease herbivore grazing, and further diminish reef function. Parrotfishes, in general, control algal growth, but overfishing has drastically reduced populations of these consumers in many parts of the world. This has allowed macroalgae to experience release from control by their grazers and in some areas macroalgae take over the reef. The classic example of this paradigm comes from Jamaica, where disease caused reductions in herbivorous urchin populations in areas where parrotfish were being exploited leaving no herbivores to graze the reef and causing a benthic phase shift from coral to macroalgal dominance [3]. This could affect the survival of other species that rely on the reef and have an ecosystem-wide impact. The local fishing industry, which depends on parrotfish, may also be negatively impacted in the long-term if overfishing causes a permanent decline in the parrotfish populations. Some parrotfish species have the habit of congregating in predictable locations in shallow water, allowing fishermen to quickly locate and spear dozens of them at once. Many countries consider parrotfish to be a delicacy, and the meat can be sold abroad by falsely labeling it as grouper, which is in higher demand. Bumphead parrotfish (Bolbometopon muricatum) are now extinct in Guam and severely depleted in Fiji, Samoa, Papua New Guinea, and other parts of the Solomon Islands as a result of these fishing pressures.
Parrotfish are valuable fishing targets in many tropical areas, especially in underdeveloped countries [4]. The local fishing economy, which depends on parrotfishes, and tourism, which depends on their presence in coral reef ecosystems, may both suffer from overfishing of parrotfishes, which can also result in a fall in the population of the species.
In addition to maintaining the structure of coral reefs, Parrotfish also play an essential role in maintaining the diversity of coral reef ecosystems. They are known to feed on a wide variety of different types of algae, which helps to prevent any one kind of algae from becoming dominant and out-competing other species. This helps to maintain a diverse and healthy ecosystem, which is essential for the survival of the many different species that call the reef home.
Parrotfish populations must be managed and regulated to prevent overfishing. To help preserve their populations, this entails actions like introducing closed seasons, imposing catch restrictions, and establishing marine protected areas. Overfishing can also be avoided by encouraging sustainable fishing methods and educating the community about the value of parrotfish in coral reef ecosystems.
In conclusion, parrotfish play an increasingly important role in the health and function of coral reefs and their accompanying ecosystems. Protecting and conserving key organisms like the parrotfish is critical to the survival of the coral reef.
Reference
- Westneat, M. W., & Alfaro, M. E. (2005). Phylogenetic relationships and evolutionary history of the reef fish family Labridae. Molecular phylogenetics and evolution, 36(2), 370-390.
- Streelman, J. T., Alfaro, M., Westneat, M. W., Bellwood, D. R., & Karl, S. A. (2002). Evolutionary history of the parrotfishes: biogeography, ecomorphology, and comparative diversity. Evolution, 56(5), 961-971.
- Hughes TP (1994) Catastrophes, phase-shifts, and large-scale degradation of a Caribbean coral reef. Science 265:1547–1551
- Edwards CB, Friedlander AM, Green AG, Hardt MJ, Sala E, Sweatman HP, Williams ID, Zgliczynski B, Sandin SA, Smith JE (2013) Global assessment of the status of coral reef herbivorous fishes: evidence for fishing effects. Proc Roy Soc B 281:20131835.
- Cover Photo: The Nature Conservancy
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