Bioerosion and sediment ingestion by the Caribbean parrotfish Scarus vetula and Sparisoma viride:implications of fish size, feeding mode and habitat use

Abstract

Erosion rates and sources of sediment ingested were quantified for the 2 most abundant parrotfish species on a leeward fringing reef of Bonaire, Netherlands Antilles: Scarus vetula and Spansoma viride. Direct estimates of erosion by different size classes were obtained from daily feeding rates and grazing scar frequency, scar volume and substrate density. Foraging preference and distribution of fish on the reef were used to examine patterns of bioerosion at 2 spatial scales: reef zones and individual substrates used for grazing. Sediment mass ingested by fish provided an independent check on erosion rates, and was partitioned according to source. S. vetula, employing a scraping feeding mode, removed less material from grazed substrates than similar sized S. vjride, which forages by excavating the substrate. Eros~on rates increased strongly with fish size in both species. The (indigestible) carbonate derived from epilithic algae accounted for all sediment ingested by juvenile fish. In adult fish, the proportion of freshly eroded carbonate substrate ingested increased with fish size. The distribution of adults of these large scarids over different reef zones determines the rate of bioerosion on a large spatial scale. The highest bioerosional rates occur on the shallow reef (ca 7 kg m-2 y r ' ) , and they decrease with depth. Parrotfish foraging preferences, and the effects of food type and skeletal density of substrates on the size of the grazing scars, cause large differences in bioerosional rates on a small spatial scale. The highest rates of bioerosion occur on substrates infested with boring algae and of low skeletal density, while high-density substrates and substrates covered with crustose corallines undergo lower rates. Living coral is rarely eaten by scarids, and largely escapes erosion by grazing.

Live coral predation by parrotfishes (Perciformes: Scaridae) in the Abrolhos Bank, eastern Brazil, with comments on the classification of species into functional groups

“…trispinosus may be recognized as a scraper or excavator depending on its body size. All juvenile parrotfishes are scrapers (Bellwood & Choat, 1990), and their excavating potential may be related to body size (Bruggemann et al, 1996). We found that larger Sc.…”

Tradeoffs between fisheries harvest and the resilience of coral reefs

“…The model was calibrated initially with demographic data of the stoplight parrotfish (Sparisoma viride) ( Fig. 1 A and B) from Bonaire in the early 1990s (22,23,24). Because fishing for parrotfish was absent at this time (20,23), and because the population of the stoplight parrotfish remained stable (25), we assumed that this dataset represents a relatively unfished demographic equilibrium.…”

“…S4). The resulting fishery model integrates the dynamics of the five dominant parrotfishes of Caribbean forereefs (29) that represent 80-95% of the total parrotfish abundance across the region (15,20,22,27). The impact of fishing was simulated with the demographic parameters as estimated for Bonaire populations, therefore assuming that total parrotfish biomass in Bonaire in the early 1990s [∼470 kg/ha (22)] constitutes a representative unfished biomass (B 0 ) for the Caribbean.…”

Biological Erosion of Marine Habitats and Structures by Burrowing Crustaceans

“…regrowth or accumulation, Brooks and Bell 2002). Since different substrata exhibit different physical characteristics, substratum composition is another factor that may influence the effects of a bioeroder (McLean 1967, Bruggemann et al 1996, Davidson et al 2008a.…”

“…For example, McLean (1967) estimated the bioerosion rate of the snail Nerita tesselata was 0.7 g yr -1 , but total bioerosion from the high densities of this snail (220 m -2 ) exceeded 9000 cm 3 yr -1 of sandstone from a site in Barbados. Per capita rates of bioerosion can be affected by numerous factors such as the frequency of bioerosive action (Bruggemann et al 1996, Smith 2008), method of bioerosion (i.e. rasping, excavating, boring), and size of the bioeroder (McLean 1967, Bruggemann et al 1996, Carreiro-Silva and McClanahan 2001, Pinn et al 2005).…”