Kyphosus Vaigiensis Research Articles

Associations among coral reef macroalgae influence feeding by herbivorous fishes

Benthic macroalgae often occur in close association with other macroalgae, yet the implications of such associations on coral reefs are unclear. We selected three pairs of commonly associated macroalgae on inshore reefs of the Great Barrier Reef and exposed them, either independently or paired, to herbivore assemblages. Pairing the palatable alga Acanthophora with the calcified and chemically defended Galaxaura resulted in a 69 % reduction in the consumption of Acanthophora, but had no effect on the consumption of Galaxaura. The reduced consumption of Acanthophora was related to 53–85 % reductions in the feeding rates of two herbivorous fish species, Kyphosus vaigiensis and Siganus doliatus. Neither Acanthophora nor Sargassum were afforded protection when paired with the brown macroalga Turbinaria. Although limited to one of the three species pairings, such associations between algae may allow the ecological persistence of palatable species in the face of intense herbivory, enhancing macroalgal diversity on coral reefs.

Brassy chubs Kyphosus vaigiensis display unexpected trans-island movement along inshore habitats

Large herbivores such as kyphosids on coral reefs are drivers of ecosystem resilience by grazing on macroalgae and providing space for coral growth. These fishes also support recreational shore fisheries and are commonly targeted for food by fishers in the tropics. Yet, little is known about their habitat utilization and movement among inshore habitats. Movement patterns of brassy chubs Kyphosus vaigiensis were investigated using passive acoustic telemetry methods along the coastline of Hawaii Island. Of particular interest, two individuals displayed unexpected trans-island movement throughout estuarine and coastal habitats, which respectively traveled 311 km and 37 km from their release site. The movement behaviors of these two individuals are highly uncharacteristic among most shore fishes, and shift our understanding of movement ranges of herbivorous shore fishes with implications for adaptive management of multiple shore fisheries resources.

SEM study of the oral cavity of members of the Kyphosidae and Girellidae (Pisces, Teleostei), with remarks on Crenidens (Sparidae), focusing on teeth and taste bud numbers and distribution

The present study compares dental morphology and taste bud distribution in the oral cavity of four species of the teleost family Kyphosidae, five species of Girellidae and one species of Sparidae. Some of these species are predominantly herbivorous, while others are omnivorous with a high portion of invertebrates in their diets. All the kyphosids feature one row of frontal cusped teeth on their jaws and areas of miniature teeth on the tongue and palate; the girellid species feature 2–5 rows of denticulate teeth, and no teeth inside the oral cavity. The total number of taste buds in the oral cavity is higher in Girella spp. than in the kyphosids, and their number is species-specific, not correlated with fish size. For example, Kyphosus bigibbus of 500mm standard length bears 1780 taste buds, while the kyphosid Neoscorpis lithophilus of 80mm bears 3460. The maximum number of taste buds, 7900, is found in Girella punctata of 60mm standard length, and the minimum number, 1320, in Kyphosus vaigiensis of 175mm. The higher number of taste buds appears to characterize species that possess a more diversified diet. The present study contributes to our understanding of the differences between the two families Kyphosidae and Girellidae. In particular, it relates the eco-morphological adaptations to the type of diet consumed by the various species.

Herbivorous fishes, ecosystem function and mobile links on coral reefs

Understanding large-scale movement of ecologically important taxa is key to both species and ecosystem management. Those species responsible for maintaining functional connectivity between habitats are often called mobile links and are regarded as essential elements of resilience. By providing connectivity, they support resilience across spatial scales. Most marine organisms, including fishes, have long-term, biogeographic-scale connectivity through larval movement. Although most reef species are highly site attached after larval settlement, some taxa may also be able to provide rapid, reef-scale connectivity as adults. On coral reefs, the identity of such taxa and the extent of their mobility are not yet known. We use acoustic telemetry to monitor the movements of Kyphosus vaigiensis, one of the few reef fishes that feeds on adult brown macroalgae. Unlike other benthic herbivorous fish species, it also exhibits large-scale (>2 km) movements. Individual K. vaigiensis cover, on average, a 2.5 km length of reef (11 km maximum) each day. These large-scale movements suggest that this species may act as a mobile link, providing functional connectivity, should the need arise, and helping to support functional processes across habitats and spatial scales. An analysis of published studies of home ranges in reef fishes found a consistent relationship between home range size and body length. K. vaigiensis is the sole herbivore to depart significantly from the expected home range–body size relationship, with home range sizes more comparable to exceptionally mobile large pelagic predators rather than other reef herbivores. While the large-scale movements of K. vaigiensis reveal its potential capacity to enhance resilience over large areas, it also emphasizes the potential limitations of small marine reserves to protect some herbivore populations.

Identity and behaviour of herbivorous fish influence large-scale spatial patterns of macroalgal herbivory in a coral reef

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 482:227-240 (2013) - DOI: https://doi.org/10.3354/meps10262 Identity and behaviour of herbivorous fish influence large-scale spatial patterns of macroalgal herbivory in a coral reef Peter J. Michael1, Glenn A. Hyndes1, Mathew A. Vanderklift1,2, Adriana Vergés1,3,4,* 1Centre for Marine Ecosystems Research, School of Natural Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup, Western Australia 6027, Australia 2CSIRO Wealth from Oceans Flagship, Private Bag 5, Wembley, Western Australia 6913, Australia 3Centre for Marine Bio-Innovation and Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2056, Australia 4Sydney Institute of Marine Science, Building 19, Chowder Bay Rd, Mosman, New South Wales 2088, Australia *Corresponding author. Email: a.verges@unsw.edu.au ABSTRACT: The functional role of macroalgae-consuming fishes is particularly important in coral reefs, as they can mediate the recovery of degraded systems when macroalgae become established. However, herbivory on coral reefs is often spatially and temporally variable, and the mechanisms that underpin variation in the consumption of algae are largely unknown. In this study, we examined local (within-reef, 100s of m) and broad-scale (regional, 100s of km) patterns of macroalgal herbivory along the spatial extent of Ningaloo Reef in northwestern Australia. Using underwater video cameras, we quantified the feeding rates of individual fish on a dominant macroalga Sargassum myriocystum, and we quantified social feeding behaviour to determine whether patterns in algal removal are influenced by whether fish feed as solitary individuals or as part of single-species or multi-species groups. While 23 fish species were observed biting macroalgae, spatial patterns in the intensity of herbivory were strongly driven by 3 species: Naso unicornis, Kyphosus vaigiensis and K. bigibbus. Feeding rates by individuals of these 3 species were always highest when individuals were part of monospecific groups, and we found a strong positive relationship between spatial patterns in the amount of macroalgae removed and the proportion of bites taken as part of groups, irrespective of fish size. This study highlights the importance of species-specific algae–herbivore interactions in coral reefs and shows that local variation in feeding behaviour is an important trait that contributes to explain spatial variability in macroalgal herbivory. KEY WORDS: Herbivory · Macroalgae · Group feeding · Naso unicornis · Kyphosus vaigiensis · Kyphosus bigibbus · Ningaloo Reef Full text in pdf format PreviousNextCite this article as: Michael PJ, Hyndes GA, Vanderklift MA, Vergés A (2013) Identity and behaviour of herbivorous fish influence large-scale spatial patterns of macroalgal herbivory in a coral reef. Mar Ecol Prog Ser 482:227-240. https://doi.org/10.3354/meps10262 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 482. Online publication date: May 22, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Filisoma filiformis n. sp. (Echinorhynchida: Cavisomidae), a New Species of Acanthocephala from Kyphosus spp. (Perciformes: Kyphosidae) from the South Pacific, and a Key to the Genus Filisoma

We describe a new species of acanthocephalan from the reef fish Kyphosus bigibbus Lacepede, Kyphosus sydneyanus (Gunther), and Kyphosus vaigiensis (Quoy and Gaimardi) from Heron Island, Queensland; Ningaloo Reef, Western Australia; and Moorea, French Polynesia, respectively. Filisoma filiformis n. sp. is differentiated primarily from other species by its long, slender proboscis, with 16–18 longitudinal rows of 42–48 hooks. The wide distribution and multiple host species of F. filiformis suggest that it could be found in other localities around the Indo-Pacific region where kyphosid fish occur. The differing patterns of host range and geographic distribution within the genus Filisoma are discussed.

Diversity among Macroalgae-Consuming Fishes on Coral Reefs: A Transcontinental Comparison

Despite high diversity and abundance of nominally herbivorous fishes on coral reefs, recent studies indicate that only a small subset of taxa are capable of removing dominant macroalgae once these become established. This limited functional redundancy highlights the potential vulnerability of coral reefs to disturbance and stresses the need to assess the functional role of individual species of herbivores. However, our knowledge of species-specific patterns in macroalgal consumption is limited geographically, and there is a need to determine the extent to which patterns observed in specific reefs can be generalised at larger spatial scales. In this study, video cameras were used to quantify rates of macroalgae consumption by fishes in two coral reefs located at a similar latitude in opposite sides of Australia: the Keppel Islands in the Great Barrier Reef (eastern coast) and Ningaloo Reef (western coast). The community of nominally herbivorous fish was also characterised in both systems to determine whether potential differences in the species observed feeding on macroalgae were related to spatial dissimilarities in herbivore community composition. The total number of species observed biting on the dominant brown alga Sargassum myriocystum differed dramatically among the two systems, with 23 species feeding in Ningaloo, compared with just 8 in the Keppel Islands. Strong differences were also found in the species composition and total biomass of nominally herbivorous fish, which was an order of magnitude higher in Ningaloo. However, despite such marked differences in the diversity, biomass, and community composition of resident herbivorous fishes, Sargassum consumption was dominated by only four species in both systems, with Naso unicornis and Kyphosus vaigiensis consistently emerging as dominant feeders of macroalgae.

Latitudinal variation in macroalgal consumption by fishes on the Great Barrier Reef

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 426:241-252 (2011) - DOI: https://doi.org/10.3354/meps09016 Latitudinal variation in macroalgal consumption by fishes on the Great Barrier Reef S. Bennett, D. 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 *Corresponding author. Email: david.bellwood@jcu.edu.au ABSTRACT: On coral reefs, herbivory is a key factor in maintaining coral-dominated systems. Despite this, few studies have investigated the process of herbivory over broad spatial scales. We examined the patterns of herbivory across sites spanning 900 km along the Great Barrier Reef (GBR), Australia. Assays were used to directly quantify the removal rates of the brown macroalgae Sargassum, while feeding rates of herbivorous fishes were measured using remote underwater video. Removal rates of Sargassum by herbivores exhibited a significant regional decline from north to south, driven primarily by changes in the behaviour of the 4 most dominant species and to a lesser extent by a regional decline in herbivore diversity. Whilst the 4 species (Naso unicornis, Kyphosus vaigiensis, Siganus doliatus and S. canaliculatus) consistently dominated feeding, jointly accounting for 85, 99 and 98% of mass standardised bites within the north, central and southern regions, respectively, they recorded over an order of magnitude fewer bites in the south. Interestingly, the decline in bites and the lower feeding diversity was not a result of lower herbivore biomass or density in the southern region. Rather, the major difference between fish herbivory among regions was the feeding propensity of the 4 dominant feeders toward the transplanted Sargassum. Reefs with intact and structurally comparable herbivore communities therefore cannot be assumed to have the same realised functional impact on the reef. Local behaviour may be an important factor. KEY WORDS: Herbivory · Spatial scale · Phase-shift · Resilience · Coral reef Full text in pdf format Supplementary material PreviousNextCite this article as: Bennett S, Bellwood DR (2011) Latitudinal variation in macroalgal consumption by fishes on the Great Barrier Reef. Mar Ecol Prog Ser 426:241-252. https://doi.org/10.3354/meps09016 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 426. Online publication date: March 28, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

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.

DNA barcoding is a useful tool for the identification of marine fishes from Japan

In this study, 229 DNA sequences of cytochrome oxidase subunit I gene (COI) from 158 marine fishes of Japan were employed to test the efficacy of species identification by DNA barcoding. The average genetic distance was 60-fold higher between species than within species, as Kimura two parameter (K2P) genetic distances averaged 17.6% among congeners and only 0.3% among conspecifics. There were no overlaps between intraspecific and interspecific K2P distances, and all sequences formed species units in the neighbor-joining dendrogram. Hybridization phenomena in two species ( Kyphosus vaigiensis and Pterocaesio digramma) were also detected through searches in Barcode of Life Data Systems (BOLD). DNA barcoding provides a new way for fish identification.

Size matters: macroalgal height influences the feeding response of coral reef herbivores

Algal size has often been related to shifts in the susceptibility of algae to herbivores. Within coral reef systems, macroalgal assays have been widely used to quantify herbivory; however, the effect of macroalgal size has been largely overlooked. I used Sargassum polycystum assays that spanned the range of available heights (10 to 80 cm) and underwater video cameras to examine the effect of macroalgal height on the rates and agents of herbivory on an inner-shelf reef of the Great Barrier Reef. Rates of herbivory were high and displayed limited variation among heights, ranging from 86.4 to 95.2% 5h–1. There was, however, significant variation in the species recorded feeding from S. polycystum of different heights. Naso unicornis dominated feeding on the shortest (10 cm) assays, while Kyphosus vaigiensis dominated feeding on the larger (20 to 80 cm) assays. This variation appears to be related to interspecific differences in foraging behaviour, and suggests that the roles of these fishes may change at different stages of benthic community succession.

Utilisation of mannitol by temperate marine herbivorous fishes

The sugar alcohol mannitol is the primary photosynthate of phaeophytes, and as such is an important dietary constituent for many marine herbivorous fishes. Sugar alcohols are not thought to be efficiently digested by vertebrates. Although vertebrates lack intestinal transporters for sugar alcohols, these compounds are thought to serve as substrates for fermentation by hindgut flora. Here, we measured mannitol in twelve species of New Zealand phaeophytes and in gut contents and gut fluid from five points along the gut of eight species of New Zealand marine herbivorous fishes: Odax pullus, Kyphosus sydneyanus, Kyphosus vaigiensis, Girella tricuspidata, Girella cyanea, Parma alboscapularis, Aplodactylus arctidens and Aplodactylus etheridgii. The mannitol content of the algae varied from 6.76% dry wt. ± 0.83 SE in Cystophora scalaris to 28.81% dry wt. ± 2.03 SE in Marginariella boryana. The fishes consumed varying amounts of mannitol, correlating with their consumption of phaeophytes. In O. pullus and K. sydneyanus the amount of mannitol in gut contents decreased markedly in the hindgut. The correlation of this decrease with the density of gut microbiota and fermentation products suggests that mannitol is fermented to short-chain fatty acids in the hindgut, rather than being directly taken up by the fish. Hindgut fermentation of mannitol may thus serve as an important mechanism for energy salvage in hindgut-fermenting fishes that feed on phaeophytes.

Taxonomic Review of the Indo-Pacific Kyphosid Fish, Kyphosus vaigiensis (Quoy and Gaimard)

The taxonomy of the Indo-Pacific fish, Kyphosus vaigiensis (Quoy and Gaimard) is reviewed and the species redescribed on the basis of 129 specimens, including the lectotype which is newly designated. Kyphosus vaigiensis is characterized by 14 (rarely 13 or 15) dorsal and 13 (rarely 12) anal fin soft-rays, 21-24 (usually 22 or 23) gill-rakers on the lower limb of the first gill-arch, 56-64 longitudinal scale rows and 11-14 (usually 12 or 13) scales above the lateral line. Kyphosus lembus (Cuvier), Kyphosus bleekeri Fowler, Kyphosus gibsoni Ogilby, Pimelepterus ternatensis Bleeker and Pimelepterus marciac Cuvier are recognized as junior synonyms of K. vaigiensis.

Fluctuations in Abundance and Species Composition of Fishes that appear in the set net fishery in the Dadohae Marine National Park

In a joint research of the Korean Biodiversity Information Facility (KBIF), the study analyzed species composition and fluctuations in abundance of fishes caught by the set net fishery installed in the offing of Impo, Dolsando in Yeosu-si, Jeollanamdo in June and September 2008. During the study period, there were 11,180 individuals of 54 species of 39 families in 8 orders that appeared in the set net fishery in the offing of the Dadohae Marine National Park. The numbers of individuals that appeared in June and September were shown in Table 2. Among the fishes caught, the Perciformes was the dominant species with 29 species of 22 families followed by the Tetraodontiformes with 6 species of 2 families and the Pleuronectiforme with 5 species of 4 families. There appeared 3 species of 3 families of the Anguilliformes and the Beloniformes, respectively. There were 4 species of 2 families of the Clupeiformes and 3 species of 2 families of the Scorpaeniformes. There was 1 species of 1 family of the Aulopiformes. During the study period, Scomber japonicus was the dominant species with 9005 individuals followed by Trichiurus lepturus with 1500 individuals and Panpus argenteus with 184 individuals. In June, Trichiurus lepturus was dominant with 1200 individuals followed by Panpus argenteus with 150 individuals and Scomberomorus koreanus with 58 individuals. In October, Scomber japonicus was the dominant species with 9000 individuals followed by Trichiurus lepturus with 300 individuals and Scomberomorus koreanus with 45 individuals. It indicates that the dominance of a species has close relationship with water temperature because fishes migrate to feed in this season. Given the frequency of appearance, Scomber japonicus and Trichiurus lepturus most frequently appeared because they were in the middle of growing into adult fishes while the frequent appearance of Scomberomorus koreanus and Panpus argenteus, which were major species of the fishing industry, contributed to the income of fishermen. There appeared rarely seen species in the offing of Yeosu like Pelamis platurus, Rachycentron canadum (Linnaeus), Lobotes surinamensis, Kyphosus vaigiensis, Abudefduf vaigiensis and Siganus fuscescens (Houttuyn). They are subtropical fishes and seem to move here due to the warmer water affected by the global warming. Additional studies on species composition and fluctuations in abundance of fishes that appear in the set net fishery in the Dadohae Marine National Park will be continuously conducted. So, they will contribute to the increase of fishermen's income by transferring the new fish species to fishermen when newly developed rare fish species are fostered in the lab and evaluated for adaptability and growth potential. The research result will be used as basic data to secure national biological resources, and create/manage biodiversity data by building a biodiversity database network.

Local variation in herbivore feeding activity on an inshore reef of the Great Barrier Reef

Threats to coral reefs may be manifested through an increase in macroalgae. Across the globe, phase-shifts from coral to macroalgal dominance have been reported from the Caribbean, Indian and Pacific Oceans. While the Great Barrier Reef (GBR) is in relatively good condition, inshore reefs may exhibit over 50% macroalgal cover. However, our understanding of the processes preventing the macroalgal expansion remains uncertain. Using a remote video bioassay approach, this study quantified herbivory in three bays along the leeward margin of Orpheus Island. Despite significant with-in bay variation in herbivory there was no detectable statistical difference in the rates of herbivory among bays. Furthermore, of the 45 herbivore species recorded from the island, only three played a significant role in bioassay removal, Siganus canaliculatus, Siganus javus and Kyphosus vaigiensis, with only one species predominating in each bay. Reefs of the GBR may therefore be more vulnerable than previously thought, with the removal of macroalgae depending on just a few species, which exhibit considerable spatial variability in their feeding behaviour.

Juveniles of Kyphosus vaigiensis (Quoy and Gaimard 1825) with reference to a senior synonym of Cantharus lineolatus Valenciennes 1830

The juveniles of Kyphosus vaigiensis (Quoy and Gaimard 1825), collected from the Indian Ocean and Japanese waters, are described with some ontogenetic morphological changes based on six specimens having 14 dorsal and 13 anal fin soft rays, 56–62 scales in a longitudinal row along the midbody, and 30–32 gill-rakers on the first gill-arch. The juveniles of K. vaigiensis smaller than ca. 42 mm in standard length (SL) have the proximal parts of the dorsal and anal fin soft-rayed portions covered with small scales, and the single outer row of the upper jaw teeth consisting of incisor-like and conically pointed teeth, the former with polycuspid tips differing from the specimens greater than ca. 68 mm SL. The holotype of Cantharus lineolatus Valenciennes 1830, 41.5 mm SL, was included here in the juveniles as K. vaigiensis. Therefore, K. vaigiensis is recognized as a senior synonym of C. lineolatus.

Characterizing fish communities associated with drifting fish aggregating devices (FADs) in the Western Indian Ocean using underwater visual surveys

We adapted a visual census method, mainly used in demersal and reef fish studies, to characterize fish communities associated to drifting fish aggregating devices (FADs) in the Western Indian Ocean. Drifting FAD associ- ated fishes from both equatorial (Seychelles) and tropical waters (Reunion Island) were examined by divers. A total of 32 species (belonging to 16 families) were observed associated with drifting FADs in equatorial waters, and 24 species (14 families) were found around FADs in tropical waters. Twenty species were found in both regions. The highest number of species observed at a single FAD was 18 (12 ± 2, mean ± SD) in equatorial and 13 (10 ± 3) in tropical waters, not counting circumnatant species loosely associated with the FAD. Some species like Kyphosus vaigiensis, Canthidermis maculata, Elagatis bipinnulata, Acanthocybium solandri and Coryphaena hippurus were observed on all or most of the surveys. In this study, the contribution in biomass of the 18 common species associated with drifting FADs (but excluding circumnatant species), represents more than 98% of the biomass. The overall biomass values of closely associated species remains well below tuna biomass estimates for circumnatant tuna schools at FADs, estimated as high as 200 tons. The species that most significantly contribute to the by-catch in tuna purse-seines logically match those that showing the highest biomass values in our surveys (Carcharhinus spp., Elagatis bipinnulata, Coryphaena hippurus, Canthidermis maculata ,a ndAcanthocybium solandri). One of the most abundant and ubiquitous species in our study was the spotted oceanic triggerfish Canthidermis maculata that sometimes formed massive schools of many thousands individuals around the drifting FADs. Future research is needed to explore the role of such non tuna species in the attraction and aggregation processes of tuna around drifting FADs.

Gorgocephalus yaaji n. sp. (Digenea: Gorgocephalidae) from the brassy chub Kyphosus vaigiensis (Perciformes: Kyphosidae) off Lizard Island, northern Great Barrier Reef and further records of G . kyphosi

A new species Gorgocephalus yaaji is described in the intestine of Kyphosus vaigiensis from the waters off Lizard Island, Queensland, Australia. It differs from Gorgocephalus kyphosi by its broader body shape, the extension of the vitellarium into the forebody, a relatively longer forebody, cirrus-sac and post-caecal region, and a shorter distance between the ventral sucker and the ovary. It differs from Gorgocephalus manteri in its size, its tandem testes, and the ratios of width, ventral sucker to ovary distance and ovary to testes distance to body-length. Gorgocephalus kyphosi is reported in the pyloric caeca of K. vaigiensis from waters off Moorea, French Polynesia, and Lizard Island, Queensland, Australia. Measurements and an illustration are given of the latter species.

The influence of diet and gastrointestinal fermentation on key enzymes of substrate utilization in marine teleost fishes

Three closely related marine teleosts with similar size, swimming mode, and habitat preference were compared to test the hypothesis that energy metabolism is linked to diet choice in the wild. Key substrate-utilization enzyme activities were assayed from white locomotory muscle and liver in a carnivore ( Scorpis violaceus), an omnivore ( Girella tricuspidata), and a herbivore ( Kyphosus sydneyanus) collected from their natural reef habitat in northeastern New Zealand. The similar energy requirements of the study fishes were reflected in specific enzyme activities of white muscle and suggested high dependence on endogenous fuel that is independent of dietary carbohydrate intake. Clear differences were found in enzymes of hepatic carbohydrate, fat, and ketone body metabolism that appear linked to diet choice and levels of gastrointestinal fermentation. Hepatic metabolism of fat and ketone bodies was also examined in New Zealand samples of the omnivorous Girella cyanea and the herbivorous Kyphosus bigibbus, and the tropical herbivorous species Kyphosus vaigiensis and Kyphosus cinerascens collected from the Great Barrier Reef, Australia. Overall, the results suggest that, like ruminants, herbivorous fishes such as Kyphosus species that rely upon gastrointestinal fermentation preferentially use lipids as major metabolic substrates by an increased capacity for lipid metabolism, and a lower capacity for glycolysis.

The status of the genera Hysterolecithoides Yamaguti, 1934, Neotheletrum Gibson & Bray, 1979 and Machidatrema León-Règagnon, 1998 (Digenea: Hemiuroidea), including a description of M. leonae n. sp. from Australian waters.

A diagnosis is given for the lecithasterid genus Hysterolecithoides Yamaguti, 1934, which is now found to have two to six (possibly seven) vitelline masses. The species H. frontilatus (Manter, 1969) is returned to the genus, having been considered a member of the bunocotylid genus Neotheletrum by recent authors. It is redescribed from Siganus nebulosus, Moreton Bay, and S. doliatus, Lizard Island, Great Barrier Reef and New Caledonia, with emphasis on the presence of Juel's organ, a uterine seminal receptacle and the blind sac associated with the genital atrium. It differs from its congeners in the trajectory of the pars prostatica which recurves dorsally to the sinus-sac. Oligolecithoides Shen, 1982 is synonymised with Hysterolecithoides and O. trilobatus Shen, 1982 is synomised with H. epinepheli Yamaguti, 1934. Machidatrema León-Règagnon, 1998 is diagnosed, and found to be close to Hysterolecithoides, but differs in the lack of a blind-sac projecting from the dorsal genital atrium, by its tandem testes, the coiling of the uterus between the testes and the ovary, and the ventral excretory pore. M. leonae n. sp. is described from Siganus fuscescens, S. lineatus, S. doliatus, S. corallinus, S. vulpinus and Scarus globiceps at Heron Island, Queensland. It differs from its closest congener, M. akeh, in the muscular and tegumental flap over the genital pore and details of the terminal genitalia. M. chilostoma (Machida, 1980) and M. kyphosi (Yamaguti, 1970) are redescribed from Kyphosus vaigiensis from Heron Island. Neotheletrum Gibson & Bray, 1979 is diagnosed: it differs from Hysterolecithoides in its confluent excretory arms, blind seminal receptacle (no Juel's organ) and uniformly tripartite vitellarium. A cladistic analysis suggests that M. chilostoma and M. kyphosi are not best accommodated in Machidatrema, that Machidatrema (sensu stricto) is monophyletic and that Hysterolecithoides is paraphyletic. Hysterolecithoides and Machidatrema are considered hysterolecithine lecithasterids, whilst Neotheletrum is retained as an opisthadenine bunocotylid.