Scarus Rivulatus Research Articles

DNA, databases and diet: a case study on the parrotfish Scarus rivulatus

DNA metabarcoding is increasingly used in dietary studies, but this molecular technique has limitations including DNA extraction, primer choice suitability and completeness of DNA reference databases. Together, these limitations can create successive biases; some of which can be identified by careful data interrogation. Here, we examine some of the influential factors impacting DNA metabarcoding by focusing on the diet of the grazing coral reef parrotfish Scarus rivulatus (Labridae). The 16S V3-4 and 18S V4 gene regions were targeted to detect a wide range of taxa in the pharyngeal content, but genus-level amplicon sequence variant (ASV) assignments were ≤ 40%. Multiple universal 18S V4 primer sets, which amplified the same portion of the gene region, highlighted disparities that impacted resulting datasets and dietary data interpretation. Approximately 50% of ASVs overlapped among these 18S V4 datasets. Overall, our results show that protein-rich epilithic and endolithic microscopic photoautotrophs were consistently present and that S. rivulatus appears to rely on protein-rich taxa, especially dinoflagellates and cyanobacteria. Even if all qualitative limitations could be addressed, our data emphasise the difficulty of making straightforward quantitative conclusions about the diet composition of grazing fishes using DNA metabarcoding alone. Thus, until DNA metabarcoding reaches a state of maturity where quantitative data can be gained, additional support is required from other dietary analysis methods to provide robust interpretations and conclusions.

Study of Microplastic Contamination in the Digestive Organs of Parrotfish (Scarus rivulatus) Caught in Ekas Bay

Microplastics have become a major concern in global environmental research due to their significant impact on marine ecosystems. Microplastic pollution has been detected in almost all aquatic environments, including oceans, rivers and lakes. This study aims to evaluate the level of microplastic contamination in the digestive organs of old parrot fish caught in Ekas Bay. Focusing on the digestive organs is important because ingested microplastics can have detrimental effects on fish health, including digestive disorders and bioaccumulation of harmful chemicals. The research method used was descriptive with a sample size of six parrot fish. Based on research conducted on the digestive organs of parrot fish, it was found that the types of microplastics found were in the form of fragments, films, pellets and fibers. The total abundance of microplastics in the intestinal organs ranges from 290 par/gr to 410 par/gr, while in the stomach organs it is 272 par/gr to 310 par/gr. The highest percentage of microplastics in the intestinal organs was pellets at 47% and in the stomach organs it was fragments at 54%.

RESTORASI EKOSISTEM PADANG LAMUN MELALUI TEKNOLOGI BIO-FADs TREE DENGAN BAHAN DASAR RUMPUT LAUT PADA PERIKANAN DEMERSAL

Coastal water ecosystems in general have experienced damage as a result of fishing that is not environmentally friendly. This unfriendly fishing causes the fish's feeding grounds to be damaged so that fishing activities in coastal areas need to involve fishing aids to collect fish. The fishing aids implemented are in accordance with the fishing objectives to be achieved. The implementation of fishing aids aims to attract attention and bring fish to the area where the attractor is installed, making it easier to catch. One of the fishing aids used is Biological Fish Aggregating Devices (Bio-FADs Tree) or live FADs equipped with Kappaphycus alvarezii seaweed which acts as an attractor to attract fish so they can be easily caught. This service is carried out in Mamuju waters for the purpose of catching demersal fish. The service is carried out using trap fishing equipment. The results of the service showed that the catches obtained were Pink ear emperor (Lethrinus lentjan), Redbelly yellowtail fusilier (Caesio cuning), Streaked spinefoot (Siganus javus), batik Vermiculated spinefoot (Siganus vermiculatus) and Orange-spotted spinefoot (Siganus gutattus), White-spotted spinefoot (Siganus canaliculatus), and Surf parrotfish (Scarus rivulatus). All of the catches are fish of important economic value

Studi distribusi tertangkapnya ikan pada Soma Tono selama satu siklus bulan

This study aims to determine the distribution of caught fish in "soma tono" and the types of fish caught and how the fish are caught. Soma Tono is classified in gillnets that are rectangular in shape and equipped with buoys, upper ropes, lower ropes, weights and sign buoys. Operation of soma tono fishing gear consists of preparation, net lowering (setting), soaking (soaking) and lifting the net (hauling). The principle of soma tono fishing gear (gillnet) is to wait for fish to be entangled in the body of the net. The method used is a descriptive method, namely managing data obtained when making observations, interviews and documentation. The dominance of fish obtained by bounced fish, the type of fish obtained is the dominance of demersal fish or bottom fish, namely jackfruit seed fish (Upeneus molluccensin), lencam fish (Letrinus lencan), snapper fish (Lutjanus campechanus), lolosi fish (Caesio chrysozona), kuwe fish (Caranx ignobilis), grouper (Epinephelus longispinis), curisi fish (Nemipterus nemaptohorus), sako fish (Tylosurus crocodilus), parrotfish (Scarus rivulatus Valenciennes), puffer fish (Tetraodontidae), sardines (Amblygaster sirm), baronang fish (Siganus) and sea eels (Muraenidae). The results obtained four phases of the moon, namely the 1st quarter moon phase (101.5 kg), the new moon phase (168.7 kg), 2nd quarter moon phase (89 kg) and the full moon phase (63kg).

Diversity of Parrotfish at Fishing Port, Kendari City, Southeast Sulawesi

Parrotfish are included in the group of herbivore fish which have an important role in aquatic ecosystems, especially in the maintenance of coral reefs. This study aimed to determine the diversity of parrotfish species in the Sodoha Fishing Port (TPI), Kendari City, Southeast Sulawesi. Identification of parrotfish species by Kuiter and Tonozuka, White, and Fishbase. The results of identification showed six species of parrotfish were obtained, namely Chlorurus microrhinos (Bleeker, 1854), C. bleekeri (Deeufort, 1940), C. strongylocephalus (Bleeker, 1855), Scarus rivulatus (Valenciennes, 1840), S. niger (Forsskål, 1775), dan S. chameleon (Choat & Randall, 1986). Utilization of parrot fish resources continues to increase by> 40% annually. Sustainable management of parrotfish is needed for the quality of the aquatic environment, especially coral reefs and the sustainability of their utilization.

Percentage of the bycatch and discard composition in artisanal bottom trap fisheries

Data on bycatch in the fishing effort required to manage fisheries resources. Unfortunately, the data on small-scale and traditional fisheries is still lacking. It makes it challenging to make fishing policies and regulations. Survey activities and experimental fishing were conducted to determine and analyze the composition of the main catch, bycatch and discarded by the local fisher's bottom traps in Sibolga, North Sumatra, Indonesia. Five units of the trap with a size of 150 cm x 100 cm x 50 cm (length x width x height) were used to collect fish data. These five trap units operated in the fishing ground, where local fishers usually operate their fishing gear. The fishing operation carried out within 1 mile of the coastline with water depths ranging from 7-10 meters. The duration of trap setting around 5-7 days for each fishing operation. A motorboat operated with a weight of 5.8 GT. The results showed that the total bottom trap catch consisted of 329 individuals with a total weight of 151.4 kg and 12 demersal fish species. The main catch was 148 individuals (88.9 kg), or 44.7% of the total catch during the experiment i.e. Chepalapholis urodeta, Ephinephelus areolatus, Epinephelus chlorostigma, Plectropomus leopardus, Ephinepelus coioides, Lates calcarifer, Lutjanus malabaricus, and Lutjanus erytropterus. The bycatch was 151 individuals (57.1 kg) or 46.1% i.e. Lethrinus obsoletus, Lutjanus ehrenbergii, Acanthurus auranticavus, Platax teira, Nemipterus japonicus, Scarus rivulatus, Lutjanus johnii, Siganus canaliculatus, Caesio cuning, and Taeniura lymma.While the discarded catch amounted to 30 individuals (5.4 kg) or 9.2% i.e. Naso brevirostris, Diodon holocanthus, and Diadema setosum. The bycatch utilization obtained by fishers was 83.4%, and the unutilized was 16.6%. The percentage of fish sizes worthy for consumption was 135 individuals (74.6%), and the size unworthy for consumption was 46 individuals (25.4%).Keywords:Fishing groundFishing gear Fishing operation Main catchTrap

Spatial distribution of parrotfishes and groupers in an Okinawan coral reef: size-related associations in relation to habitat characteristics.

Parrotfishes (Labridae: Scarini) and groupers (Epinephelidae) are important fish groups that are regarded as the fisheries targets of primary importance in coral reefs. In order to establish ecosystem-based management of these two fish groups, clarifying the spatial distribution relative to habitat characteristics is of central importance. The present study investigated the spatial distributions of 12 parrotfishes species and seven groupers species in relation to environmental characteristics in an Okinawan coral reef. Ten out of the 12 parrotfish species and all seven grouper species showed species-specific spatial distributions. Four substrate types in the inner reefs (branching Acropora, bottlebrush Acropora, dead branching Acropora, and dead bottlebrush Acropora), three substrate types in the exposed reefs (massive coral, other coral, and calcium carbonate substratum), and water depth showed significant associations with the spatial distribution of fishes. Among the 12 parrotfish species, two species (Scarus spinus and S. forsteni) and four species (S. psittacus, S. hypselopterus, S. dimidiatus and S. ghobban) were primarily found in exposed reefs and inner reefs, respectively. Among the seven grouper species, two species (Cephalopholis argus and C. urodeta) and two other species (C. miniata and Epinephelus ongus) were primarily found in exposed reefs and inner reefs, respectively. Size-related spatial distribution was also found for three parrotfish species (Chlorurus microrhinos, Scarus rivulatus and S. hypselopterus), indicating that smaller-sized and larger-sized individuals were respectively found at sites with greater coverage of substrates with fine structure (live bottlebrush Acropora and dead bottlebrush Acropora) and coarse structure (live branching Acropora, dead branching Acropora and calcium carbonate substratum). The present study suggested that the spatial distribution of parrotfishes and groupers is not necessarily associated with the higher coverage of living corals, but positively associated with high substrate complexity. Thus, actual spatial distributional patterns of species should be considered to select candidate sites for protection and conservation for the two fish groups.

Reproductive strategy of rivulated parrotfish Scarus rivulatus Valenciennes, 1840

The rivulated parrotfish Scarus rivulatus is a reef fish that use not to be a target fish, but is now becoming a fisheries target. This change in status is causing the rivulated parrotfish population to be depressed due to fishing effort and interspecific and intraspecific competition in their habitat. This research aimed to examine the parrotfish’s reproductive strategies and tactics. The parameters observed were sex ratio, gonad maturity and first maturity at the female and male. Sex and gonad maturity was determined based on the macroscopic characteristics of the gonads. First maturity was estimated based on the total length. This study indicates that the sex-ratio of rivulated parrotfish was unbalanced, males was fewer than females (1: 2.49). The maturity stages of male and female were quite synchronous. Early maturation and maturity stages that were dominant during the study indicate that rivulated parrotfish can spawn at any time throughout the year. The size at first maturity of rivulated parrotfish was achieved very quickly with sizes 16.9 for female cm and 24.3 cm for male. Females that mature more quickly are an indication that the rivulated parrotfish is protogynous. An imbalance in sex ratios, spawning at any time throughout the year, early maturity, and protogynous could be a strong indication that rivulated parrotfish was an r-strategy.

Temporal variation in macroalgal removal: insights from an impacted equatorial coral reef system

Macroalgal removal is a critical ecosystem function yet few studies have considered its temporal variability, especially on impacted reefs with limited herbivorous fish biodiversity. To address this, we quantified macroalgal removal and mass-standardised bite rates of herbivorous fishes monthly from July 2016 to June 2017 using a series of transplanted Sargassum ilicifolium assays and underwater video cameras on three degraded coral reefs in Singapore: Pulau Satumu, Kusu Island, and Terumbu Pempang Tengah. Our results revealed a distinct temporal pattern in macroalgal herbivory (proportion of biomass removed and mass-standardised bite rates) rates across all sites, increasing from July and decreasing from January, with the highest rates recorded in December (28.10 ± 3.05 g 3.5 h−1; 208.24 ± 29.99 mass-standardised bites 3.5 h−1) and the lowest in May (0.86 ± 0.17 g 3.5 h−1; 9.55 ± 3.19 mass-standardised bites 3.5 h−1). These coincided with the S. ilicifolium growth cycle, confirming previous evidence that herbivory rates are closely linked to macroalgal condition. Video analyses revealed nine species feeding over a year (31,839 bites; 8702.89 mass-standardised bites), with Siganus virgatus responsible for sim 80% of the total mass-standardised bites. Siganus virgatus took the largest proportion of bites monthly, except between April and June, when Scarus rivulatus was dominant, suggesting temporal constraints in functional roles.

The Pattern of Herbivorous Fish Assemblages in The In Western and Eastern Outermost Island Indonesia

The herbivorous fishes have been considered as a critical functional group and have capability maintaining coral reef resilience and avoiding coral-algal phase-shifts. The present condition shown, almost in tropical reef location, alga has dominated coral, even in the small outer island. The requirement to conduct comprehensive basic research in studying the patterns and composition of herbivorous fish, especially on the small outer islands. Twelve coral reef sites in eastern Indonesia (Liki Islands) and western Indonesia (Natuna Island) used as a research location for comparing the structure patterns of herbivorous fish communities (diversity, density, and body size) using the Underwater Visual Census (UVC) method. There was different pattern of herbivorous fishes families in Liki Island and Natuna Islands, where Acanthuridae is dominant in eastern Indonesia (Liki Islands), including Ctenochaetus striatus (41,00 ± 11,72 se) individuals/350m2, A. maculiceps (23,33 ± 13,61 se) individuals/350m2, Naso hexacanthus (18,67 ± 6,34 se) individuals/350m2 while Scaridae is dominant in western Indonesia (Natuna island), including Scarus rivulatus (31,67 ± 10,61 se) individuals/350m2, Chlorurus sordidus (30,00 ± 8,52 se) individuals/350m2 and Scarus quoyi (19,00 ± 9,73 se) individuals/350m2. Based on herbivore fishes composition Liki Island has a higher density and biomass compared to Natuna Island.Keywords: herbivore, fish, coral, small outer island, Indonesia

The Utilitation of Fish Scale Waste as A Chitosan

Fish scales are fishery waste that can still be utilized because many contain chemical compounds such as organic proteins (41–84%), and the rest are mineral residues and inorganic salts. Fish scales are reported to contain proximate, calcium, and chitin. Chitin can be extracted into chitin by the deasetillation process. Chitosan is a biomaterial that can be used as a food preservative, a pharmaceutical ingredient. This research aims to extract chitin from fish scales and find out the comparison of chitin rendemen in different types of fish. The study was conducted from July to September 2020. Samples of fish scales Upeneus mullocensisi, Lethrinus sp., Caesio chrysozona, and Scarus rivulatus were obtained from the Traditional Market and Morotai Culinary Center. The process of making chitosan is carried out in the FPIK Laboratory of Universitas Pasifik Morotai. The extraction of chitosan from fish scales through three stages is deproteination, demineralization, and deasetilation. The results showed the protein and mineral content of fish scales vary, namely Upeneus mullocensisi (67.83% and 29.84%), Lethrinus sp. (36.80% and 15.99%), Caesio chrysozona (51.84% and 22.99%), and Scarus rivulatus (82.96% and 14.31%). The highest chitosan rendemen in Lethrinus sp. (13.22%), followed by Caesio chrysozona (7.74%), Upeneus mullocensisi (0.80%), and Scarus rivulatus (0.05%). Some chitosan characteristics, such as color, shape, and smell, meet commercial chitosan standards.

Growth and condition factor of rivulated parrotfish, Scarus rivulatus in Kulisusu Bay, North Buton, Southeast Sulawesi

The growth and condition factor of rivulated parrotfish (Scarus rivulatus) was studied in Kulisusu Bay of North Buton Southeast Sulawesi from April to July 2019. Fish samples were collected using gillnets of 11/2, 2, and 21/2 inches mesh size. Growth parameters were analyzed following von Bertalanffy formula using ELEFAN I software of package program of FiSAT II. A total of 300 fish individuals was caught ranging from 145-300 mm in the total length and 63.8-461.8g in weight. The length–weight relationship of male was isometric, while female and combined sexes were negative allometric. The von Bertalanffy growth models for male, female, and combined sexes, were Lt = 310.8{1- e -0.89(t-0.011)}; Lt = 230.48{1- e -0,46(t+0,16)}; Lt = 304.5{1- e -1,2(t-0,064)}, respectively. A high value of b in male indicates this fish is getting enough food. The relative condition factor of fish varied from 0.80 to 3.45. The male has greather condition factors than female fish during this research. This shows male fish in good condition.

Parrotfish grazing ability: interspecific differences in relation to jaw-lever mechanics and relative weight of adductor mandibulae on an Okinawan coral reef.

Parrotfishes (family Labridae: Scarini) are regarded to have important roles for maintaining the ecosystem balance in coral reefs due to their removal of organic matter and calcic substrates by grazing. The purpose of the present study was to clarify the interspecific differences in grazing ability of five parrotfish species (Chlorurus sordidus, C. bowersi, Scarus rivulatus, S. niger and S. forsteni) in relation to interspecific differences in jaw-lever mechanics and the relative weight of the adductor mandibulae (muscles operating jaw closing). The grazing ability was calculated by using stomach contents (CaCO3 weight/organic matter weight) defined as the grazing ability index (GAI). There were significant interspecific differences in GAI (C. sordidus = C. bowersi > S. rivulatus > S. niger = S. forsteni). Teeth of C. sordidus and C. bowersi were protrusive-shape whereas teeth of S. rivulatus, S. niger and S. forsteni were flat-shape. C. sordidus and C. bowersihave jaw-lever mechanics producing a greater biting force and have a larger weight of adductor mandibulae. S. rivulatus has jaw-lever mechanics producing a greater biting force but a smaller weight of adductor mandibulae that produce an intermediate biting force. In contrast, S. niger and S. forsteni have jaw-lever mechanics producing a lesser biting force and have a smaller weight of adductor mandibulae. Feeding rates and foray size of S. rivulatus, S. niger and S. forsteni were greater than C. sordidus and C. bowersi. The degree in bioerosion (GAI × feeding rate) was the largest for S. rivulatusand the smallest for S. forsteni. The degree in bioerosion for C. sordidus was larger than S. niger whereas relatively equal between C. bowersi and S. niger. These results suggest that interspecific difference in GAI was explained by interspecific differences in teeth shape, jaw-lever mechanics and relative weight of adductor mandibulae. The interspecific difference in the degree of bioerosion suggests the importance of various size of parrotfishes with diverse feeding modes to maintain healthy coral reef ecosystems.

Low-quality sediments deter grazing by the parrotfish Scarus rivulatus on inner-shelf reefs

Elevated sediment loads in the epilithic algal matrix (EAM) deter grazing by herbivorous fishes and may compromise their critical roles on coral reefs. However, the properties of sediments that drive herbivore deterrence are unknown. Binary choice trials in aquaria were used to examine the effects of three sediment attributes—sediment source, grain size and organic load—on grazing by the abundant inner-shelf parrotfish, Scarus rivulatus. Fish were presented with a choice between EAM-covered rocks treated with (a) terrigenous or reefal sediments, (b) fine or coarse sediments or (c) sediments with high or low organic loads. Scarus rivulatus did not show a preference for sediments from different sources (terrigenous vs. reefal); however, a clear preference was evident for fine-grained sediments over coarse (109 % more bites) and sediments with high organic loads over low (147 % more bites). The avoidance of coarse sediments is likely to be a key factor driving the inhibition of grazing on mid-shelf reefs, which are dominated by coarse sediments. In contrast, on inner-shelf reefs, grazing by parrotfishes may be deterred primarily by high sediment loads, which reduce the proportional organic content in EAM sediments. Our study highlights the potential impact of sediments on critical ecological processes and the threats posed by changing sediment loads on inner-shelf reefs.

Similarity in the feeding ecology of parrotfish (Scaridae) in coral reef habitats of the Malaysian South China Sea, as revealed by fatty acid signatures

To understand the trophic ecology and habitat use of coral reef fish, the fatty acid composition and levels were examined in three species of parrotfish, Scarus psittacus: Scarus quoyi and Scarus rivulatus, which were collected at the Bidong Island of the Malaysian South China Sea. The proportions of saturated fatty acids (SAFA) are 57.6–64.9%, where fatty acids have the highest proportion, monounsaturated fatty acids (MUFA) (25.3–25.9%) have the second highest proportion, and polyunsaturated fatty acids (PUFA) (9.2–17.1%) have the lowest proportion. Palmitic acid (C16:0) is the most common acid in SAFA, palmitoleic acid (C16:1) is the dominant acid in MUFA, and eicosatrienoic acid (C20:3n3) and eicosapentaenoic acid (EPA, C20:5n3) have the highest proportions in PUFA. The composition of each fatty acid does not differ among species, which suggests that the feeding ecology and habitat use of the fish in the coral reef ecosystem are similar. The fatty acid concentrations, particularly that of PUFA, increase with the fish growth, which suggests that the diet and habitat shift during the life history of the fish. The diet shifts revealed by the fatty acid composition and levels suggest the similarity in habitat use and feeding ecology of those types of parrotfish.

Fatty acid composition indicating diverse habitat use in coral reef fishes in the Malaysian South China Sea.

BackgroundIn order to understand feeding ecology and habitat use of coral reef fish, fatty acid composition was examined in five coral reef fishes, Thalassoma lunare, Lutjanus lutjanus, Abudefduf bengalensis, Scarus rivulatus and Scolopsis affinis collected in the Bidong Island of Malaysian South China Sea.ResultsProportions of saturated fatty acids (SAFA) ranged 57.2% 74.2%, with the highest proportions in fatty acids, the second highest was monounsaturated fatty acids (MUFA) ranged from 21.4% to 39.0% and the proportion of polyunsaturated fatty acids (PUFA) was the lowest ranged from 2.8% to 14.1%. Each fatty acid composition differed among fishes, suggesting diverse feeding ecology, habitat use and migration during the fishes’ life history in the coral reef habitats.ConclusionsDiets of the coral fish species might vary among species in spite of that each species are living sympatrically. Differences in fatty acid profiles might not just be considered with respect to the diets, but might be based on the habitat and migration.

How far do schools of roving herbivores rove? A case study using Scarus rivulatus

Herbivorous reef fish play an important role in shaping ecosystem processes on coral reefs. Often found in schools, Scarus rivulatus, is an abundant herbivorous species on the Great Barrier Reef (GBR), Australia, especially on inshore reefs. Recent evidence has highlighted the limited spatial movements of some herbivorous fishes. However, individuals in schools are thought to be much more mobile. The aim of this study, therefore, was to evaluate the spatial range of schooling S. rivulatus to measure the spatial scale over which they exert their functional role. Furthermore, we assess the influence of the schooling behaviour on their feeding rates and thus their ecological impact. The diurnal movements of S. rivulatus were monitored using acoustic transmitters and a passive acoustic array for up to 7 months in Pioneer Bay, Orpheus Island, GBR. In addition, behavioural observations recorded school size-frequency distributions and feeding rates of S. rivulatus inside and outside foraging schools. Despite schooling, all S. rivulatus were site attached. On average, the maximum potential home range of individuals was 24,440 m2 and ranges overlapped extensively in individuals captured from the same school. School size was highly variable, with a mean school size of 5.7 individuals. Schooling had a significant impact on the functional role of individuals, with feeding rates in schools being two times higher for S. rivulatus and over three times higher for other scarid species. Our results suggest that, despite schooling, individual S. rivulatus only rove over a limited area of reef (occupying a linear stretch of reef, measuring only approximately 250 m for individuals and 220 m for entire schools). Each individual may therefore have little impact on the spatial resilience of coral reefs.

Temporal variation in coral reef ecosystem processes: herbivory of macroalgae by fishes

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 422:239-251 (2011) - DOI: https://doi.org/10.3354/meps08916 Temporal variation in coral reef ecosystem processes: herbivory of macroalgae by fishes Carine D. Lefèvre*, David R. Bellwood Australian Research Council Centre of Excellence for Coral Reef Studies and School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia *Email: carine.lefevre@jcu.edu.au ABSTRACT: Despite the widely accepted importance of fish herbivory on coral reefs, few studies have considered the temporal variability in the nature of algal–herbivore interactions. We therefore quantified monthly feeding intensity on Sargassum sp. bioassays for 12 mo with remote underwater video cameras deployed to identify the herbivores responsible for macroalgal removal on an inshore island of the Great Barrier Reef, Australia. Significantly higher removal rates were observed during the summer months whereas winter months were characterized by 4 times lower removal rates. However, rather than being simply changes in the feeding activity of a single species, this temporal pattern in herbivory also incorporated changes in the species responsible for the removal of Sargassum. Video analyses revealed that, of the 43 herbivore species recorded from the bay, only 3 played a significant role in Sargassum removal: Kyphosus vaigiensis, Naso unicornis and Scarus rivulatus. K. vaigiensis, a rudderfish, was primarily responsible for the removal of Sargassum during the summer months (83% of the total recorded bites; 85553 bites). There was almost no feeding activity on Sargassum by K. vaigiensis during the winter months (82 bites). However, there was a reciprocal increase in feeding intensity on Sargassum by parrotfishes in the winter months, particularly S. rivulatus (71 bites during summer versus 2884 bites in winter). This temporal variability in herbivore functional roles suggests that functional redundancy on reefs may be less than previously assumed in that the feeding activities of fishes may be both spatially and temporally constrained. KEY WORDS: Regime shift · Kyphosus vaigiensis · Trophic status · Phase shift · Resilience · Functional redundancy · Macroalgae · Sargassum · Great Barrier Reef Full text in pdf format Supplementary material PreviousNextCite this article as: Lefèvre CD, Bellwood DR (2011) Temporal variation in coral reef ecosystem processes: herbivory of macroalgae by fishes. Mar Ecol Prog Ser 422:239-251. https://doi.org/10.3354/meps08916 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 422. Online publication date: January 31, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Interspecific variation in spawning time and male mating tactics of the parrotfishes on a fringing coral reef at Iriomote Island, Okinawa

Spawning time and male mating tactics of parrotfishes (family Scaridae) were investigated on a fringing coral reef at Iriomote Island, Okinawa. Spawning was observed in 14 species, and more frequently in more abundant species such as Chlorurus sordidus, Scarus rivulatus and Chlorurus bowersi. At the reef-edge spawning site, C. bowersi spawned at high tide, C. sordidus spawned both at high tide and in the early morning, whereas Calotomus carolinus and most of the Scarus species such as S. rivulatus spawned only in the early morning, mostly 0630–0830 h. Spawning only in the early morning irrespective of tide phase and moon age has seldom been reported from the scarid species of other localities. It is suggested that spawning in the early morning would be adaptive in species such as S. rivulatus, which migrated considerable distances (ca. 500 m) to the inshore feeding sites, in order to minimize feeding losses due to migration. For male mating tactics, pair spawning by territorial TP (terminal phase) males occurred in all 14 species, and streaking and group spawning by nonterritorial small IP (initial phase) males were seen more frequently in more abundant species. Moreover, group spawning by nonterritorial TP males, which were larger than the IP males but smaller than the territorial TP males, frequently occurred in S. rivulatus. Such mating tactics of TP males have not been reported from Scaridae.

Dynamics of parrotfish grazing scars

Parrotfishes exhibit a range of feeding modes. These species vary in both feeding morphology and behaviour, but the vast majority of species leave distinctive scars on the substratum when feeding. Although the role of parrotfishes in reef resilience is well documented, the basis of this role and the effect of their grazing scars on the benthic community structure remain unclear. This study evaluated the dynamics of grazing scars of large adult Scarus rivulatus and Chlorurus microrhinos on an inshore reef in the Great Barrier Reef (GBR). These species represent the most abundant scraping and excavating parrotfish species on inshore reefs. Grazing scars of each species were marked, measured and observed for seven consecutive days. S. rivulatus grazing scars were smaller in area and volume and more rapidly reoccupied by algae than those of C. microrhinos. However, because of the higher abundance and feeding frequency of S. rivulatus at the study site, this species had higher algal removal rates than C. microrhinos. These species appear to play distinctly different functional roles in shaping the benthic community of inshore GBRs. S. rivulatus is primarily responsible for algal dynamics dominated by vegetative regrowth. In contrast, C. microrhinos opens relatively large areas which remain clear for several days. These scars may represent settlement sites which are relatively free from algae and sediment. This study provides new information on the differences between scraping and excavating parrotfishes and, in a system with just one abundant large excavating species, emphasizes the potential for low functional redundancy in high diversity coral reef systems.