Extraordinary Aggressive Behavior from the Giant Coral Reef Fish, Bolbometopon muricatum, in a Remote Marine Reserve

Abstract

Human impacts to terrestrial and marine communities are widespread and typically begin with the local extirpation of large-bodied animals. In the marine environment, few pristine areas relatively free of human impact remain to provide baselines of ecosystem function and goals for restoration efforts. Recent comparisons of remote and/or protected coral reefs versus impacted sites suggest remote systems are dominated by apex predators, yet in these systems the ecological role of non-predatory, large-bodied, highly vulnerable species such as the giant bumphead parrotfish (Bolbometopon muricatum) has received less attention. Overfishing of Bolbometopon has lead to precipitous declines in population density and avoidance of humans throughout its range, contributing to its status as a candidate species under the U. S. Endangered Species Act and limiting opportunities to study unexploited populations. Here we show that extraordinary ecological processes, such as violent headbutting contests by the world’s largest parrotfish, can be revealed by studying unexploited ecosystems, such as the coral reefs of Wake Atoll where we studied an abundant population of Bolbometopon. Bolbometopon is among the largest of coral reef fishes and is a well known, charismatic species, yet to our knowledge, no scientific documentation of ritualized headbutting exists for marine fishes. Our observations of aggressive headbutting by Bolbometopon underscore that remote locations and marine reserves, by inhibiting negative responses to human observers and by allowing the persistence of historical conditions, can provide valuable opportunities to study ecosystems in their natural state, thereby facilitating the discovery, conservation, and interpretation of a range of sometimes remarkable behavioral and ecological processes.

Possible sexual dimorphism in Pankowskichthys libanicus (Neopterygii, Pycnodontiformes) from the Cenomanian of Lebanon

“…This case of sexual dimorphism in cranial osteology is also similar to the rare cases found in extant teleosts today such as Kurtus gulliveri (Berra and Humphrey, 2002), Danionella dracula (Britz et al 2009), Bolbometopon muricatum (Muñoz et al, 2012) and Coryphaena hippurus (Schuck, 1951). This finding indicates that sexual dimorphism may be especially pronounced in pycnodonts and may reveal that similar taxa currently classified as distinct species may be sexual dimorphs of one another.…”

Peer Review #2 of "Spawning aggregation behavior and reproductive ecology of the giant bumphead parrotfish, Bolbometopon muricatum, in a remote marine reserve (v0.1)"

“…In those cases, some morphological female fish may be males that have not yet developed the male forehead morphology. In our study, all observations of courtship and spawning that we observed were between dimorphic fish, presumably female and male Suzuki et al, 2008;Muñoz et al, 2012).…”

“…The pair then slowly ascended to one meter below the water's surface, releasing a clearly visible gamete cloud, followed by a slow descent back to the school. Muñoz et al (2012) first documented ritualized head-butting behavior of Bolbometopon associated with earlymorning spawning events of an unexploited and intact population at Wake Atoll, and suggested PeerJ reviewing PDF | (v2014:09:2680:1:0:NEW 4 Nov 2014)…”

“…Domeier 2012 where aggregations (of unknown function at the time) of Bolbometopon were observed during biennial surveys by the NOAA CRED (see Fig. 3 in Muñoz et al, 2012). Additionally, the elevated densities (6.2 -420 times greater than other locations or non-aggregation days, respectively) of fish and spawning that we observed at the aggregation site bolster Gladstone's (1986) Our study supports the idea that Bolbometopon forms resident spawning aggregations (RAs), with possibly some features (lunar periodicity, migrations) characteristic of transient spawning aggregations (TAs) (Colin, 2012b;Domeier, 2012;.…”

Mass spawning aggregation of the giant bumphead parrotfish Bolbometopon muricatum

“…Given the extent of the aggregation and the apparent ephemeral nature of temporary dichromatism, it was difficult to ascertain numbers of males and females. No clear evidence of territoriality or aggressive interactions such as male–male chases (Muñoz et al, ) or head butting (Muñoz et al, ) were observed during the main aggregation or on review of video footage.…”