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Extraordinary aggressive behavior from the giant coral reef fish, Bolbometopon muricatum, in a remote marine reserve.

Muñoz RC, Zgliczynski BJ, Laughlin JL, Teer BZ - PLoS ONE (2012)

Bottom Line: Endangered Species Act and limiting opportunities to study unexploited populations.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.

View Article: PubMed Central - PubMed

Affiliation: National Marine Fisheries Service, Beaufort Laboratory, National Oceanic and Atmospheric Administration, Beaufort, North Carolina, United States of America. roldan.munoz@noaa.gov

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.

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Sexual dimorphism in Bolbometopon muricatum.(a) Female Bolbometopon (lower fish) and male (upper), illustrating dimorphic forehead profile which slopes caudal to beak in females but is nearly parallel with beak in males. Males are also typically larger than females [8]. All observations of courtship and spawning that we observed were between dimorphic fish, suggesting that sex can be determined in the field based on a combination of morphology and behavior [37], [38]. This assumes that most female fish interacting with morphological and behavioral males are indeed female (but see [8,37,39, Muñoz et al. in prep]). (b) Detail of male forehead showing ossified ridge characteristic of large males. The ossified ridge and cephalic hump are reduced in females.
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pone-0038120-g002: Sexual dimorphism in Bolbometopon muricatum.(a) Female Bolbometopon (lower fish) and male (upper), illustrating dimorphic forehead profile which slopes caudal to beak in females but is nearly parallel with beak in males. Males are also typically larger than females [8]. All observations of courtship and spawning that we observed were between dimorphic fish, suggesting that sex can be determined in the field based on a combination of morphology and behavior [37], [38]. This assumes that most female fish interacting with morphological and behavioral males are indeed female (but see [8,37,39, Muñoz et al. in prep]). (b) Detail of male forehead showing ossified ridge characteristic of large males. The ossified ridge and cephalic hump are reduced in females.

Mentions: Though rumored to use their forehead to ram corals prior to ingestion [15], the enlarged cephalic hump of Bolbometopon may be a classic example of a secondary sexual characteristic resulting from sexual selection (Fig. 2a), such as the massive horns in male bighorn sheep (Ovis canadensis). In addition, Bolbometopon males exhibit what appears to be an “ossified ridge” on the forehead (Fig. 2b) that may serve a similar function as the cranial appendages of artiodactyls. Any correlations between male hump, body size, and mating success remain to be determined. Freshwater cyprinid (minnows) and mormyrid (elephantfishes) species are reported to headbutt, but males do not display morphological characters (cranial appendages) associated with headbutting (but see breeding tubercles) [24], [25], [26]. In addition, physical contact in these fishes is not confined to the forehead but may also be directed at the body or tail.


Extraordinary aggressive behavior from the giant coral reef fish, Bolbometopon muricatum, in a remote marine reserve.

Muñoz RC, Zgliczynski BJ, Laughlin JL, Teer BZ - PLoS ONE (2012)

Sexual dimorphism in Bolbometopon muricatum.(a) Female Bolbometopon (lower fish) and male (upper), illustrating dimorphic forehead profile which slopes caudal to beak in females but is nearly parallel with beak in males. Males are also typically larger than females [8]. All observations of courtship and spawning that we observed were between dimorphic fish, suggesting that sex can be determined in the field based on a combination of morphology and behavior [37], [38]. This assumes that most female fish interacting with morphological and behavioral males are indeed female (but see [8,37,39, Muñoz et al. in prep]). (b) Detail of male forehead showing ossified ridge characteristic of large males. The ossified ridge and cephalic hump are reduced in females.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368943&req=5

pone-0038120-g002: Sexual dimorphism in Bolbometopon muricatum.(a) Female Bolbometopon (lower fish) and male (upper), illustrating dimorphic forehead profile which slopes caudal to beak in females but is nearly parallel with beak in males. Males are also typically larger than females [8]. All observations of courtship and spawning that we observed were between dimorphic fish, suggesting that sex can be determined in the field based on a combination of morphology and behavior [37], [38]. This assumes that most female fish interacting with morphological and behavioral males are indeed female (but see [8,37,39, Muñoz et al. in prep]). (b) Detail of male forehead showing ossified ridge characteristic of large males. The ossified ridge and cephalic hump are reduced in females.
Mentions: Though rumored to use their forehead to ram corals prior to ingestion [15], the enlarged cephalic hump of Bolbometopon may be a classic example of a secondary sexual characteristic resulting from sexual selection (Fig. 2a), such as the massive horns in male bighorn sheep (Ovis canadensis). In addition, Bolbometopon males exhibit what appears to be an “ossified ridge” on the forehead (Fig. 2b) that may serve a similar function as the cranial appendages of artiodactyls. Any correlations between male hump, body size, and mating success remain to be determined. Freshwater cyprinid (minnows) and mormyrid (elephantfishes) species are reported to headbutt, but males do not display morphological characters (cranial appendages) associated with headbutting (but see breeding tubercles) [24], [25], [26]. In addition, physical contact in these fishes is not confined to the forehead but may also be directed at the body or tail.

Bottom Line: Endangered Species Act and limiting opportunities to study unexploited populations.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.

View Article: PubMed Central - PubMed

Affiliation: National Marine Fisheries Service, Beaufort Laboratory, National Oceanic and Atmospheric Administration, Beaufort, North Carolina, United States of America. roldan.munoz@noaa.gov

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.

Show MeSH
Related in: MedlinePlus