Surgeonfish Acanthurus Bahianus Research Articles

Geographical gradients of marine herbivorous fishes: patterns and processes

We present new data and the first rigorous analysis of latitudinal and thermal gradients of diversity, density and biomass of marine herbivorous fishes and review proposed explanatory mechanisms. Consistently, negative relationships between latitude, and positive relationships between sea surface temperature (SST), and relative richness and relative abundance of herbivorous fishes were found worldwide. Significant differences in the strength of gradients of richness and abundance with latitude and SST between tropical and extratropical zones were found consistently across ocean basins. Standardized sampling along the western Atlantic also showed negative relationships between latitude and total density and biomass. The trends, however, are driven by different components of the fish assemblages (i.e., scarids in the Caribbean and acanthurids in Brazil). Patterns of abundance along thermal gradients, generally associated with extensive latitudinal gradients, also were found at the local scale. Feeding rate of the ocean surgeonfish Acanthurus bahianus decreases with temperature more rapidly than the mean metabolic rate of teleost fishes. This relationship suggests a temperature-related physiological constraint. From the new standardized and comparative data presented and the review of the explanatory hypotheses, we conclude that temperature-related feeding and digestive processes are most likely involved in the distribution patterns of herbivorous fishes.

Ocean surgeonfish Acanthurus bahianus. I. The geography of demography

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 295:229-244 (2005) - doi:10.3354/meps295229 Ocean surgeonfish Acanthurus bahianus. I. The geography of demography D. R. Robertson1,*, J. L. Ackerman2, J. H. Choat2, J. M. Posada3, J. Pitt4 1Smithsonian Tropical Research Institute (Panamá), STRI, Unit 0948, APO, AA 34002-0948, USA2School of Marine Biology and Aquaculture, James Cook University, Townsville 4811, Australia3Departamento de Biología de Organismos, Universidad Simón Bolívar, Apartado 89000, Caracas 1080-A, Venezuela4Benthic Ecology Laboratory, Bermuda Biological Station for Research, Biological, Station Lane, GE-01, Ferry Reach, Bermuda *Email: drr@stri.org ABSTRACT: The ocean surgeonfish Acanthurus bahianus is a common inhabitant of reefs throughout the west and central Atlantic. We examined geographic variation in its demography among 10 locations spanning 56° of latitude. These populations exhibit a great diversity of growth trajectories, as well as 3-fold variation in terminal size and maximum longevity. There are strongly contrasting patterns of habitat variation in demography at 2 sites: at Bermuda, fish settle inshore, grow to about asymptotic size and then, when 2 to 6 yr old, relocate permanently to outer reefs, where they can reach 32 yr. At Belize, fish settle and attain 10 yr on both inner and outer reefs, but grow faster and reach a ~50% greater asymptotic weight on inner reefs. Habitat differences in growth at Belize largely span the range of variation among NW Atlantic locations. A. bahianus exhibits the fastest growth known for an acanthurid, and the strongest spatial variation in demography known for a tropical reef-fish. Maximum age, adult survivorship, terminal size and absolute growth rate are inversely related to temperature. However, relative growth rate is not: in all populations a similar percentage of mean asymptotic standard length (L∞) is achieved at 1, 2 and 3 yr, and then growth effectively ceases. Variation in longevity is related to temperature, and is largely independent of size. Variation in growth and size is related strongly to both habitat and temperature effects, and the rate of growth appears to set terminal size. High longevity at 3 isolated oceanic islands seems to reflect a temperature effect, rather than an island effect. KEY WORDS: Acanthuridae · Acanthurus bahianus · Tropical West Atlantic · Otolith · Longevity · Growth · Size · Temperature Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 295. Online publication date: June 23, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

Ocean surgeonfish Acanthurus bahianus. II. Fishing effects on longevity, size and abundance?

The ocean surgeonfish Acanthurus bahianus, an abundant small herbivore on reefs throughout the tropical west and central Atlantic, is a significant component of Caribbean trap- fishery catches. To assess effects of fishing on this species we compared its longevity, survivorship, size and abundance at localities throughout its range that have differing intensities and targets of fishing. Temperature explains nearly all of the geographic variation in maximum longevity of A. bahianus, and most of the variation in adult survivorship, with no indications of consistent fishing effects on either. Variation in maximum and median length (1.6-fold) and in abundance (16-fold) also are not consistently related to fishing. A. bahianus has similar demographic characteristics at 2 neigh- bouring (50 km apart) offshore Venezuelan reefs, one a well protected reserve, the other with intense fishing for predators. At Panama, the abundance of adult A. bahianus showed no trend of change from 1979 to 1997, as the local density of subsistence fishers increased by ~70%. The lack of consis- tent fishing-effects on this species found in this and some other studies may reflect a combination of (1) resilience to fishing mortality arising from rapid growth to asymptotic size, early maturity, small size and abundance, and (2) strong, natural, large- and small-scale spatial variation in demography and abundance obscuring any such effects. Effects of non-catastrophic fishing on sedentary reef- fishes with similar demographic characteristics probably will be revealed only through comparisons of subpopulations in adjacent fished and no-take areas involving careful consideration of small-scale habitat effects.

Spatial and temporal patterns of distribution and abundance of a tropical fish assemblage in a seasonal Sargassum bed, Cabo Frio Island, Brazil

The patterns of distribution and abundance of a fish community were influenced by the magnitude of the canopy of Sargassum furcatum. It is suggested that the fish community in the sublittoral of Farol Beach is structured mainly by factors related to the availability of space and habitats. Quantitative data were collected by visual census techniques, along a belt of 30X2 m in each habitat. Fish diversity was greater in S. furcatum bed and in the rocks, than in the sand where there is less structural complexity. The fish density was related to the macroalgal biomass. Correspondence analysis and cluster analysis were used to describe and compare fish assemblages in three different habitats. The association observed between the juveniles of the sparid Diplodus argenteus, the grunt Haemulon aurolineatum and the surgeonfish Acanthurus bahianus and the different habitats in the summer, and juveniles of the other species in the autumn, indicates a pattern of recruitment of the species in these periods.

Seasonal grazing rates and food processing by tropical herbivorous fishes

Seasonal variability in grazing rates and food‐processing characters were assessed for three abundant fishes in a tropical rocky shore: the damselfishStegastes fuscus, the parrotfishSparisoma atomarium, and the surgeonfishAcanthurus bahianus. Significant differences were found in grazing rates among hour of day and seasons, and in food‐processing characters among seasons for the three fishes. Grazing rates forS. atomariumandA. bahianuspeaked at 1300 and 1400 hours forS. fuscus. Three main periods of different intensity in bite rates, low, intermediate and intense, were identified for all fishes. As expected, total bite rates, ingestion rates and gut fullness were highest inA. bahianus, the largest species studied, followed byS. atomariumandS. fuscus. S. atomariumwith fused jaw teeth, holds the highest bite size andS. fuscusthe lowest one. Gut turnover was high forS. fuscusand similar forS. atomariumandA. bahianus. Grazing rates and food‐processing characters seem to vary between seasons not only due to changes in temperature, but also affected by other factors. Fishes employ different food‐processing mechanisms and bear some differences in food‐processing characters to achieve optimal energetic supplies from a poor nutrient food resource.

Effects of habitat on the settlement and post-settlement success of the ocean surgeonfish Acanthurus bahianus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 161:51-59 (1997) - doi:10.3354/meps161051 Effects of habitat on the settlement and post-settlement success of the ocean surgeonfish Acanthurus bahianus Andrea Risk* Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada N9B 3P4 *E-mail: sale@server.uwindsor.ca Local population dynamics of fishes on coral reefs are dependent on processes affecting the settlement of pelagic larvae and the subsequent persistence of these new settlers. The ability of larvae to choose favourable places to settle in terms of persistence may make the dynamics of certain populations predictable at the reef scale, and cause patterns of recruitment to differ from those of larval supply. I collected data on settlement, recruitment and persistence of the ocean surgeonfish Acanthurus bahianus in different physiographic zones of the Tague Bay reef, on the island of St. Croix, U.S. Virgin Islands. There was significantly higher settlement and recruitment to the back-reef zone than to the fore-reef zone or seagrass zones at the bases of the back-reef and fore-reef, suggesting that larvae select settlement sites and do not necessarily settle to the first reef zone encountered. On the back-reef, settlers used pavement more than any other type of substratum, and the post-settlement persistence of settlers and recruits was highest on pavement when compared to these other substrata. These results suggest that patterns of ocean surgeonfish settlement are affected by reef-based processes, and that selection for certain zones and substrata occurs. Subsequent modification of these initial settlement patterns by increased persistence in preferred habitats adds predictability to patterns of recruitment, resulting in larval supply alone being an insufficient explanation of the distribution and abundance of ocean surgeonfish populations at this scale. Coral reef fish · Caribbean · Otoliths · Habitat selection · Recruitment · Growth · Persistence Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 161. Publication date: December 31, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.