Sophie J. McCoy

Animals often occupy home ranges where they conduct daily activities. In many parrotfishes, large terminal phase (TP) males defend their diurnal (i.e., daytime) home ranges as intraspecific territories occupied by harems of initial phase (IP) females. However, we know relatively little about the exclusivity and spatial stability of these territories. We investigated diurnal home range behavior in several TPs and IPs of five common Caribbean parrotfish species on the fringing coral reefs of Bonaire, Caribbean Netherlands. We computed parrotfish home ranges to investigate differences in space use and then quantified spatial overlap of home ranges between spatially co-occurring TPs to investigate exclusivity. We also quantified the spatial overlap of home ranges estimated from repeat tracks of a few TPs to investigate their spatial stability. We then discussed these results in the context of parrotfish social behavior. Home range sizes differed significantly among species. Spatial overlap between home ranges was lower for intraspecific than interspecific pairs of TPs. Focal TPs frequently engaged in agonistic interactions with intraspecific parrotfish and interacted longest with intraspecific TP parrotfish. This behavior suggests that exclusionary agonistic interactions may contribute to the observed patterns of low spatial overlap between home ranges. The spatial overlap of home ranges estimated from repeated tracks of several TPs of three study species was high, suggesting that home ranges were spatially stable for at least 1 month. Taken together, our results provide strong evidence that daytime parrotfish space use is constrained within fixed intraspecific territories in which territory holders have nearly exclusive access to resources. Grazing by parrotfishes maintains benthic reef substrates in early successional states that are conducive to coral larval settlement and recruitment. Behavioral constraints on parrotfish space use may drive spatial heterogeneity in grazing pressure and affect local patterns of benthic community assembly. A thorough understanding of the spatial ecology of parrotfishes is, therefore, necessary to elucidate their functional roles on coral reefs.

Parrotfishes are widely considered to be important grazers on coral reefs that remove autotrophic biomass from the reef substrate and create bare space that is conducive to larval coral settlement and recruitment (Bonaldo et al., 2014). Another aspect of parrotfish foraging and trophic ecology that has received very little attention is coprophagy. Coprophagy, the consumption of fecal matter, occurs in many animal taxa and may be an important means of subsidizing nutritional requirements (i.e., micro- and macronutrients) not met through foraging on preferred resources alone (Bailey & Robertson, 1982; Johannes & Satomi, 1966; Negro et al., 2002; Robertson, 1982).

The feces of planktivorous fishes, including Chromis spp., have been identified as important sources of nutrients and trace elements to tropical and temperate reef ecosystems (Geesey et al., 1984; Hamner et al., 1988; Pinnegar & Polunin, 2006). Their feces are readily consumed by a variety of fishes, including parrotfishes (Pinnegar & Polunin, 2006; Robertson, 1982). Although parrotfish coprophagy has been observed in prior studies (Motta & Overholtzer, 1999; Robertson, 1982), its frequency has not yet been quantified.

In May–July 2019, we conducted video-recorded foraging observations of 162 parrotfishes across five fringing coral reef sites in Bonaire, NL to quantify benthic foraging targets for the five most common species on those reefs

Abstract

Animals often occupy home ranges where they conduct daily activities. In many parrotfishes, large terminal phase (TP) males defend their diurnal (i.e., daytime) home ranges as intraspecific territories occupied by harems of initial phase (IP) females. However, we know relatively little about the exclusivity and spatial stability of these territories. We investigated diurnal home range behavior in several TPs and IPs of five common Caribbean parrotfish species on the fringing coral reefs of Bonaire, Caribbean Netherlands. We computed parrotfish home ranges to investigate differences in space use and then quantified spatial overlap of home ranges between spatially co-occurring TPs to investigate exclusivity. We also quantified the spatial overlap of home ranges estimated from repeat tracks of a few TPs to investigate their spatial stability. We then discussed these results in the context of parrotfish social behavior. Home range sizes differed significantly among species. Spatial overlap between home ranges was lower for intraspecific than interspecific pairs of TPs. Focal TPs frequently engaged in agonistic interactions with intraspecific parrotfish and interacted longest with intraspecific TP parrotfish. This behavior suggests that exclusionary agonistic interactions may contribute to the observed patterns of low spatial overlap between home ranges. The spatial overlap of home ranges estimated from repeated tracks of several TPs of three study species was high, suggesting that home ranges were spatially stable for at least 1 month. Taken together, our results provide strong evidence that daytime parrotfish space use is constrained within fixed intraspecific territories in which territory holders have nearly exclusive access to resources. Grazing by parrotfishes maintains benthic reef substrates in early successional states that are conducive to coral larval settlement and recruitment. Behavioral constraints on parrotfish space use may drive spatial heterogeneity in grazing pressure and affect local patterns of benthic community assembly. A thorough understanding of the spatial ecology of parrotfishes is, therefore, necessary to elucidate their functional roles on coral reefs.

Abstract
The concurrent rise in the prevalence of conspicuous benthic cyanobacterial mats and the incidence of coral diseases independently markmajor axes of degradation of coral reefs globally. Recent advances have uncovered the potential for the existence of interactions between the expanding cover of cyanobacterial mats and coral disease, especially black band disease (BBD), and this intersection represents both an urgent conservation concern and a critical challenge for future research. Here, we propose links between the transmission of BBD and benthic cyanobacterial mats. We provide molecular and ecophysiological evidence suggesting that cyanobacterial mats may create and maintain physically favorable benthic refugia for BBD pathogens while directly harboring BBD precursor assemblages, and discuss how mats may serve as direct (mediated via contact) and indirect (mediated via predator–prey–pathogen relationships) vectors for BBD pathogens. Finally, we identify and outline future priority research directions that are aligned with actionable management practices and priorities to support evidence-based coral conservation practices.

Parrotfishes can often be observed consuming fish feces on coral reefs. Our recent study highlights the nutritional value of these feces to parrotfishes.  Four of the five most common speciesa t our study sites (Bonaire, Caribbean Netherlands) consumed feces, mostly from Chromis multilineata. Despite being infrequent (<4% total bites), we estimate that coprophagy may contribute ~27% of the carbon obtained by parrotifhses while foraging on preferred benthic substrates. Chromis feces also have higher protein and lipid conetents and lower C:N:P ratios than other foraging targets (algae and cyanobaceteria). Coprophagy is, thereofre, likely an important nad understudied component of parrotfish nutrition.

Read more at: https://www.jstor.org/stable/48657233

https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.3657