The Likelihood of Extinction of Iconic and Dominant Herbivores and Detritivores of Coral Reefs: The Parrotfishes and Surgeonfishes

Abstract

Parrotfishes and surgeonfishes perform important functional roles in the dynamics of coral reef systems. This is a consequence of their varied feeding behaviors ranging from targeted consumption of living plant material (primarily surgeonfishes) to feeding on detrital aggregates that are either scraped from the reef surface or excavated from the deeper reef substratum (primarily parrotfishes). Increased fishing pressure and widespread habitat destruction have led to population declines for several species of these two groups. Species-specific data on global distribution, population status, life history characteristics, and major threats were compiled for each of the 179 known species of parrotfishes and surgeonfishes to determine the likelihood of extinction of each species under the Categories and Criteria of the IUCN Red List of Threatened Species. Due in part to the extensive distributions of most species and the life history traits exhibited in these two families, only three (1.7%) of the species are listed at an elevated risk of global extinction. The majority of the parrotfishes and surgeonfishes (86%) are listed as Least Concern, 10% are listed as Data Deficient and 1% are listed as Near Threatened. The risk of localized extinction, however, is higher in some areas, particularly in the Coral Triangle region. The relatively low proportion of species globally listed in threatened Categories is highly encouraging, and some conservation successes are attributed to concentrated conservation efforts. However, with the growing realization of man's profound impact on the planet, conservation actions such as improved marine reserve networks, more stringent fishing regulations, and continued monitoring of the population status at the species and community levels are imperative for the prevention of species loss in these groups of important and iconic coral reef fishes.

Functional over-redundancy and high functional vulnerability in global fish faunas on tropical reefs

“…Thus, the exceptional biodiversity characterizing tropical biotas does not preclude functional vulnerability because even the loss of a few species may erode the breadth of functions performed in assemblages. For instance, the Indo-Australian Archipelago (Coral Triangle), which supports most tropical-reef fish species, may experience a loss of FEs following fisheries pressure and local species extirpation (26). When seeking particularly vulnerable functional trait categories across fish faunas, it appears that only few are over-or underrepresented into FEs (Fig.…”

Native species exploited by marine aquarium trade in Brazil

“…Similarly to other fish kept in aquaria, such as surgeonfish (mainly living plant consumers) and parrotfish (primarily detrital aggregates feeders), angelfish perform vital ecological roles in coral reef trophodynamics (e.g. controlling sponge and tunicate densities) (Hourigan et al 1989, Hill 1998, Sazima et al 1999, Andréa et al 2007, Konow & Bellwood 2011, Reis et al 2012 and, thus, their overexploitation and inter-specific relationships had also being object of concern (Hill 1998, Comeros-Raynal et al 2012). Nevertherless, the potential impact of fisheries targeting aquarium reef fish in Brazil is difficult to be evaluated, because little is known about the distribution of this type of fishing effort throughout the country and the actual level of threat to reef fish is hard to be assessed (Floeter et al 2006).…”

“…Such initiatives, instead of preserving a particular species, aim not only the protection of the whole ecosystem but also assure the continuity of inter and intra-specific associations, including the safety of important spawning aggregation sites that are crucial for the survival of some aquarium traded species (Friedlander 2001, Gerhardinger et al 2009, Comeros-Raynal et al 2012, Feitosa et al 2015.…”

Herbivory and the resilience of Caribbean coral reefs: knowledge gaps and implications for management

“…Given the high levels of current and historical fishing throughout much of the Caribbean and the observation that even low levels of fishing can limit the populations of larger, slower-growing species, fishing is almost certainly a major factor limiting the abundance of large parrotfishes in many locations. Indeed, the largest species in the Caribbean, Scarus guacamaia, S. coelestinus, and S. coeruleus, are rare or absent on most reefs (Hawkins & Roberts 2003, Kramer 2003 and are most abundant in places with little or no fishing pressure (Debrot et al 2008, Comeros-Raynal et al 2012). In addition, biomass of intermediate-sized parrotfishes, such as Sparosoma viride and Scarus vetula are negatively correlated with fishing pressure across much of the region (Hawkins & Roberts 2003).…”