Parrot Grazing Effects on Coral Health
Parrotfish, as well as many other marine species, plays a significant role in the growth and development of coral reefs. There are fourteen various species of reef parrotfish, known in the Caribbean
Parrot Grazing Effects on Coral Health
Parrotfish, as well as many other marine species, plays a significant role in the growth and development of coral reefs. There are fourteen various species of reef parrotfish, known in the Caribbean Sea (Rotjan & Lewis, 2005). These fish are considered as the most abundant and the most dominate biomass of herbivorous fishes on Caribbean reefs. They consume macro algae that would otherwise outcompete hermatypic corals for space. Nevertheless, they have a negative effect on coral reefs’ health by regularly consuming live corals. This work discusses and evaluates the positive and negative effects of parrotfish on coral health.
Unfortunately, nowadays the coral cover is in decline on many Caribbean reefs. Thus, any process that can damage or destroy corals is a potential concern. Many factors, such as pollution, temperature change, and coral diseases cause an irreversible damage to the coral colonies. The results of various researches show that frequent and intense disturbance has increased in several past decades. Such disturbance has a negative effect on the main demographic processes of coral communities, such as population size and composition. Consequently, the repetitive decline in the great amount of long-lived structure building corals has resulted in a prevalence of short-lived “weedy” coral species (Roff, Ledlie, Ortiz, & Mumby, 2011). These drastic changes in ecosystem structure and function of corals have aroused interest in processes that have an impact on demographic rates in corals. Different scientists have investigated the impact of parrotfish on the coral colonies in the Caribbean Sea.
According to Mumby (2009), parrotfish grazing benefits coral recruitment in three different ways. First of all, it promotes encrusting coralline algae and reducing macro algae, which contributes to increase of the settlement space for corals. It also helps to prevent the growing thick algal turfs that might trap sediment and produce post-settlemen destruction in coral recruits (Mumby, 2009). In a similar manner, reducing macroalgae may decrease the repetitiveness and endurance of competitive interactions between coral recruits and macro algae (Mumby, 2009). According to the researcher, such interactions may drastically decrease recruit growth rates, and their survivorship. Despite the fact that parrotfish benefits corals by consuming macro algae, the number of recent researches made in the different areas of the Caribbean Sea demonstrate the damage caused by these species.
In their research, McCauley et al. (2014) used the bumphead parrotfish (Bolbometopon muricatum) to evaluate the supposed connections between the functional importance of the species and effects on ecosystem structure and dynamics. The research was performed by scientists in two biogeographically similar central Pacific atolls in the Northern Line Islands Archipelago. The researchers spent 1745 min of focal follow data from five bump head parrotfish individuals (McCauley et al., 2014). The results of their research demonstrate that the bite approximate frequency is 3.3 bites/min (McCauley et al., 2014). Scientists note, that about 59.3% of bites were taken from the dead coral substrate, and 40.1% were taken from 