Acanthuridae Research Articles

Rapid changes in fish utilization of mangrove habitat in Western Madagascar

Fish use of a mangrove habitat was studied in a small mangrove forest on the West coast of Madagascar. A sand bar near the inlet retains water in parts of the channel (pools) at low tide. Fishes in four of these pools were examined daily at all phases of the tidal cycle for 3 weeks using underwater visual census. During week 1, fishes were diverse and abundant in all pools: the dominant species were cardinalfish (related to Apogonlateralis); monos, Monodactylus argenteus; black spotted snappers, Lutjanus ehrenbergi; double bar bream, Acanthopagrus bifasciatus; emperors, Lethrinus lentjan and L. sp., surgeon fish, Acanthurus nigricauda; red-lined sweetlips, Plectorhinchus plagiodesmis; and butterflyfish, Chaetodon kleini. Some species were more abundant in shaded pools; others in more open pools. During week 2 a dramatic difference was noted: the only fishes found were schools of cardinalfish and one moray eel. This week had neap tides, with high tides in the morning and low tides in the afternoon. As the week progressed and during week 3 (spring tides), fishes slowly repopulated the habitat and diversity increased. Monos, absent in week 2, now had increasing numbers of small individuals. While large emperors were scarce, small individuals appeared. The larger butterflyfish and surgeonfish seen in week 1 were replaced by small ones during week 3. Species that had been rare in week 1 were more abundant, including pipefish and small barracudas. While species richness increased during week 3, the community was strikingly different from that seen 2 weeks earlier. Only Pool 1, closest to the entrance, recovered its original species richness. Abundance was much lower than in week 1. Our snapshot study apparently captured a time when older juveniles left the mangrove forest and smaller fishes recruited into it. Utilization of this habitat will likely vary throughout the year depending on the reproductive cycle of the different species whose juveniles utilize it. Longer studies are needed to learn about cycles in fish use of the mangroves.

Species diversity and quantitative distribution of the surgeon fishes (Family: Acanthuridae) along Aqaba Gulf, Red Sea, Egypt.

his study aims to estimate the diversity and distribution of surgeon fishes (Acanthuridae) on reef flat and slope along Aqaba Gulf, Red Sea. The inner reef flat of Aqaba Gulf is characterized by high non-living substrate, whereas at the middle reef the contributions of living materials are flourished with algae. On the other hand, the outer reef flat and slope are characterized by welldeveloped coral communities. On the Egyptian coast of Aqaba Gulf, the total number of the surgeon fish was 8 species (Acanthurus gahhm, A. nigrofuscus, A. sohal, Ctenochaetus striatus, Naso lituratus, N. unicornis, Zebrasoma desjardinii and Z. xanthurum). A. nigrofuscus and C. striatus were abundant at most sites. The southern sites have the highest number of species, while the northern ones were the lowest. The patterns of habitats play a role in the species distribution of the acanthurids; some preferred the reef flat (A. nigrofuscus, A. sohal and C. striatus), while others preferred the reef slope (A. gahhm, N. lituratus, N. unicornis, Z. desjardinii and Z. xanthurum). Most acanthurids have territories on reefs. A. sohal has large territories on outer reef flat. An analysis of the fish fauna confirmed that there are differences between northern and southern parts of Aqaba Gulf in terms of fish assemblages.

A new species of Anuretes Heller, 1865 (Copepoda: Caligidae) from the yellowbanded sweetlips Plectorhinchus lineatus (Haemulidae) off New Caledonia

A new species of caligid copepod, Anuretes justinei n. sp., is described from off New Caledonia. It is parasitic on the gill filaments of a haemulid fish, the yellowbanded sweetlips Plectorhinchus lineatus (Linnaeus). The new species is distinguished from its congeners by the combination of the following character states: (1) the fourth pedigerous somite is covered dorsally by the expanded free posterior margin of the cephalothorax; (2) a maxillary whip is present; (3) the relatively small genital complex is less than half the length of the cephalothorax; (4) leg 3 is armed with nine setae on the terminal exopodal segment and six setae on the terminal endopodal segment; and (5) leg 4 is long and slender with a setal armature of I, III twisted spines. The new species is an addition to the possibly monophyletic group of seven species that is characterised by the possession of a maxillary whip, all of which are found on haemulid hosts. The host-specificity of Anuretes is relatively high, its species being largely parasitic on reef-associated fishes, such as the families Haemulidae (eight species), Ephippidae (four species), Acanthuridae (four species) and Pomacanthidae (one species).

Scale and Benthic Composition Effects on Biomass and Trophic Group Distribution of Reef Fishes in American Samoa1

We determined spatial patterns in distribution and biomass of 163 fish species in nearshore waters around Tutuila Island, American Samoa. Visual surveys of reef fishes along 30 by 5 m belt transects were conducted using a hierarchical nested design at five spatial scales from individual transects to tens of kilometers, allowing assessment of broad geographic patterns. Benthic cover data were derived from video transect surveys to test the relationship between habitat and distributions of reef fishes. We found that fish biomass, density, and numerical abundance in American Samoa are dominated by herbivores from relatively few species in the families Acanthuridae and Scaridae. Subsets of carnivore species covaried positively with live coral, algae, and coralline algae cover. Herbivores, in contrast, covaried positively with filamentous algae and coralline algae (i.e., their foods). Biomass of fishes at different trophic categories was associated with higher abundance of food material and habitat availability. Significantly higher biomass occurred along the south shore of Tutuila and at reefs with greater exposure to wave energy, such as topographic points, despite the occurrence of lower live coral cover. Significant variations in fish biomass occurred at large spatial scales, specifically at habitat and exposure levels. Variations at these scales were apparently driven by association of the most dominant trophic group with its food source and the extent but not the quality of habitat.

Territorial behaviour of Acanthurus sohal and Plectroglyphidodon leucozona on the fringing Egyptian Red Sea reefs

We studied territorial behaviour of the acanthurid surgeonfish Acanthurus sohal and pomacentrid damselfish Plectroglyphidodon leucozona on fringing reefs in Ras Mohammed National Park, Red Sea, Egypt. We investigated trespass times, the number of agonistic acts, their intensity and the agonism elicited (number agonistic acts/total trespass time) for all intruders. Five families (Pomacentridae, Chaetodontidae, Acanthuridae, Labridae and Scaridae) were dominant among the 14 we recorded in our study sites. Seven species belonging to four families were resident inside A. sohal territories. Of the other 66 species we observed, 45 are intruders. The territory-holder did not react equally agonistically toward all these intruders. A. sohal showed a high number of agonistic acts against conspecifics and the parrotfish Cetoscarus bicolor. The intensity of the agonistic encounters, however, showed a different picture, with a low level for conspecifics and C. bicolor, respectively. A. sohal showed a high degree of agonistic intensity toward only one parrotfish, Chlorurus sordidus. The highest values of ‘Agonism elicited’ were recorded against Scarus ghobban, followed by Siganus rivulatus and Zebrasoma desjardinii . Despite these high values, the intensity was relatively weak. The territories of A. sohal were large (average 12.5 m2); those of P.␣leucozona were ca. 20 times smaller (average 0.6 m2). A. sohal spent most of their time swimming (patrolling) along the territory border, stopping briefly to feed on algae. On the other hand, P. leucozona spent most of their time swimming and sheltering.

The trophic status of herbivorous fishes on coral reefs

Estimates of feeding rates, alimentary tract structure and temporal patterns of food processing obtained from twelve species of nominally herbivorous fishes on the northern Great Barrier Reef were compared. These included members of the families Acanthuridae, Scaridae and Kyphosidae. Based on an analysis of diet and short-chain fatty acid (SCFA) profiles from a previous study we initially partitioned the twelve species into four dietary categories, as follows: (a) Category 1: herbivores with a diet of macroscopic brown algae and high SCFA profiles in the hindgut region (Naso unicornis, Kyphosus vaigiensis); (b) Category 2: herbivores feeding on turfing and filamentous red and green algae with moderate SCFA profiles in the hindgut region (N. tonganus, K. cinerascens, Zebrasoma scopas, Acanthurus lineatus); (c) Category 3: zooplankton feeders with moderate SCFA profiles (N. vlamingii, N. brevirostris); (d) Category 4: species feeding on detrital and sedimentary materials with low levels of SCFA (Chlorurus microrhinos, Scarus schlegeli, Ctenochaetus striatus, A. olivaceus). The purpose of this comparison was to determine whether measures of feeding activity, alimentary tract structure, and food processing were concordant with diet. A dichotomy in feeding rates was observed. Species with a diet of algae and zooplankton (categories 1–3) had slower feeding rates than those feeding on detrital aggregates and sediment (category 4). The pattern of food processing also followed the same dichotomy with species of categories 1–3 retaining food in the alimentary tract overnight and commencing the feeding day with substantial amounts of food in the intestine and hindgut. Category-4 species commenced the feeding day with empty alimentary tracts suggesting a rapid turnover of gut contents. Within the herbivorous and zooplankton-feeding species neither alimentary tract structure nor food processing mode were predicted by diet or SCFA profiles. A hindgut fermentation chamber was present in K. vaigiensis but not in N. unicornis, a species with high levels of SCFA in the hindgut region and a diet of brown macroscopic algae. In contrast N. vlamingii, with a diet dominated by animal matter, retained large amounts of food material in a hindgut chamber over the entire feeding cycle. In tropical perciform fishes, herbivory and fermentation are not associated with the alimentary tract structures that characterise herbivorous terrestrial vertebrates. Estimates of the abundance of the different groupings of nominally herbivorous fishes indicated that the dominant elements in the reef grazing and browsing fauna were consumers of detrital and sedimentary materials. These could not be classified as herbivores. Members of this group were dominant in all habitats investigated. Explicitly herbivorous taxa were a minority component in all habitats investigated.

Rapid evolutionary divergences in reef fishes of the family Acanthuridae (Perciformes: Teleostei)

A phylogenetic analysis of the surgeonfish family Acanthuridae was conducted to investigate: (a) the pattern of divergences among outgroup and basal ingroup taxa, (b) the pattern of species divergences within acanthurid genera, (c) monophyly in the genus Acanthurus, and (d) the evolution of thick-walled stomach morphology in the genera Acanthurus and Ctenochaetus. Fragments of the 12S, 16S, t-Pro, and control region mitochondrial genes were sequenced for 21 acanthurid taxa (representing all extant genera) and four outgroup taxa. Unweighted parsimony analysis produced two optimal trees. Both of these were highly incongruent with a previous morphological phylogeny, especially with regard to the placement of the monotypic outgroups Zanclus and Luvarus. The maximum likelihood tree and the morphological phylogeny were not significantly different and the conflicting branches were very short. Split decomposition analysis identified conflict in the placement of long basal branches separated by short internodes, providing further evidence that long branch attraction is an important cause of disagreement between molecular and morphological trees. Parametric bootstrapping rejected hypotheses of monophyly of: (a) the genus Acanthurus and (b) a group containing representatives of Acanthurus/ Ctenochaetus with thick-walled stomachs. The branching pattern of the likelihood and split decomposition trees indicates that evolution in the acanthurid clade has involved at least three periods of intense speciation.

Cleaner fish Labroides dimidiatus recognise familiar clients.

Individual recognition has been attributed a crucial role in the evolution of complex social systems such as helping behaviour and cooperation. A classical example for interspecific cooperation is the mutualism between the cleaner fish Labroides dimidiatus and its client reef fish species. For stable cooperation to evolve, it is generally assumed that partners interact repeatedly and remember each other's past behaviour. Repeated interactions may be achieved by site fidelity or individual recognition. However, as some cleaner fish have more than 2,300 interactions per day with various individuals per species and various species of clients, basic assumptions of cooperation theory might be violated in this mutualism. We tested the cleaner L. dimidiatus and its herbivorous client, the surgeon fish Ctenochaetus striatus, for their ability to distinguish between a familiar and an unfamiliar partner in a choice experiment. Under natural conditions, cleaners and clients have to build up their relationship, which is probably costly for both. We therefore predicted that both clients and cleaners should prefer the familiar partner in our choice experiment. We found that cleaners spent significantly more time near the familiar than the unfamiliar clients in the first 2 minutes of the experiment. This indicates the ability for individual recognition in cleaners. In contrast, the client C. striatus showed no significant preference. This could be due to a sampling artefact, possibly due to a lack of sufficient motivation. Alternatively, clients may not need to recognise their cleaners but instead remember the defined territories of L. dimidiatus to achieve repeated interactions with the same individual.

New species of Balantidium and Paracichlidotherus (Ciliophora) inhabiting the intestines of four surgeonfish species from the Tuvalu Islands, Pacific Ocean.

Four species of adult herbivorous surgeonfishes (Family Acanthuridae) were collected from the remote South-Pacific island system of Tuvalu. Their intestinal contents were examined, and of four populations of ciliated protists, two new species were discovered and are described. Ciliates were examined after protargol staining and, in some cases, scanning electron microscopy. Members of each population were examined and 10 characters measured for the balantidia, and 13 for the paracichlidotherids. A new Balantidium is described which has an unusually large dextr-oral field of cilia. A new species of Paracichlidotherus was discovered which has a macronucleus significantly smaller and well anteriad the cytoplasmic portion of the oral polykinetids relative to the type species.

Parasite distribution on client reef fish determines cleaner fish foraging patterns

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 235:217-222 (2002) - doi:10.3354/meps235217 Parasite distribution on client reef fish determines cleaner fish foraging patterns Redouan Bshary1,2,*, Alexandra S. Grutter3 1Max-Planck-Institut für Verhaltensphysiologie, Seewiesen, Postfach 1564, 82305 Starnberg, Germany 2University of Cambridge, Department of Zoology, Downing Street, Cambridge CB2 3EJ, United Kingdom 3Department of Zoology and Entomology, The University of Queensland, Brisbane, Queensland 4072, Australia *Address for correspondence: University of Cambridge, Department of Zoology, Downing Street, Cambridge CB2 3EJ, United Kingdom. E-mail: rb286@cam.ac.uk ABSTRACT: Recent evidence suggests that cleaner fish Labroides dimidiatus effectively control parasite densities on client reef fish that actively visit them to have parasites and dead or infected tissue removed. These findings support the hypothesis that clients benefit from cleaning. However, they do not show how cleaners reduce the parasite load of their clients. Cleaners could selectively feed on parasites or parasite removal could be a side product of cleaners foraging indifferently on the client surface, resulting in the removal of healthy mucus and scales also. To investigate cleaner fish foraging behaviour, we infected individuals of the surgeon fish Ctenochaetus striatus, with parasitic monogeneans on one body side, while the other body side was parasite free. We then allowed these clients to interact with L. dimidiatus. We found that the duration of interactions depended on parasite load, and that cleaners spent both more time and took more bites per time unit on the infected than on the uninfected side. Our data thus support the idea that parasite abundance determines food patch quality for cleaners. The overall outcome of cleaning interactions is thus likely to benefit the clients. KEY WORDS: Cleaning behaviour · Cooperation · Mutualism · Selective foraging · Labroides dimidiatus Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 235. Online publication date: June 19, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

The Phylogenetic Relationships of the Suborder Acanthuroidei (Teleostei: Perciformes) Based on Molecular and Morphological Evidence

Fragments of 12S and 16S mitochondrial DNA genes were sequenced for 14 acanthuroid taxa (representing all six families) and seven outgroup taxa. The combined data set contained 1399 bp after removal of all ambiguously aligned positions. Examination of site saturation indicated that loop regions of both genes are saturated for transitions, which led to a weighted parsimony analysis of the data set. The resulting tree topology generally agreed with previous morphological hypotheses, most notably placing the Luvaridae within the Acanthuroidei, but it also differed in several areas. The putative sister group of Acanthuroidei,Drepane,was recovered within the suborder, and the sister group of the family Acanthuridae,Zanclus,was likewise recovered within the family. Morphological characters were included to produce a combined data set of 1585 characters for 14 acanthuroid taxa and a single outgroup taxon. An analysis of the same 15 taxa was performed with only the DNA data for comparison. The total-evidence analysis supports the monophyly of the Acanthuridae. A parametric bootstrap suggests the possibility that the paraphyly of Acanthuridae indicated by the molecular analyses is the result of long-branch attraction. The disagreement between molecular and morphological data on the relationships of the basal acanthuroids and its putative sister taxon is unresolved.

Comparisons of abundance of coral‐reef fish: Catch and effort surveys vs visual census

Abstract Catch per unit effort (CPUE) in fisheries science and visual counts in marine ecology are widely used to provide estimates of relative abundance. Concurrent use of these techniques therefore offers an opportunity for cross‐validation. This study compares CPUE to underwater visual census (UVC) estimates of relative species abundance in a multispecies fishery: coral‐reef fish in the Solomon Islands. Multivariate analyses showed large differences between CPUE and UVC estimates of abundance. The families Acanthuridae and Scandae tended to be the primary cause of differences between the techniques when the full assemblage offish was analysed. However, the relationship between CPUE and UVC did not improve when these families were excluded from the data set and the analyses repeated on families (Serranidae, Lutjamdae, Lethrinidae) caught by the predominant gear type, handlining. This result highlights the point that the choice and use of particular methods require careful consideration in conjunction with the nature of factors being investigated. Many problems of sampling are specific to particular methods and some investigations may benefit from a more pluralistic approach.

OF REEF FISHES, OVERFISHING AND IN SITU OBSERVATIONS OF FISH TRAPS IN ST. JOHN, U.S. VIRGIN ISLANDS

Fishing with a variety of methods and gears, including traps, is allowed within the waters of Virgin Islands National Park (St. 10hn, U.S. Virgin Islands). Randall's 1 9 6 1 observation of the effects of overushing in nearshore waters off Sto John has been followed by three and a half decades of reports documenting the declining reef fish catch in the Virgin Islands and much of the Caribbean. To assess the state of the trap fishery in St. John waters, traps set by fishers were visually censused in situ in 1992, 1993 and 1994 both inside and outside park waters. Fifty-nine species of fishes representing 23 families and 1340 individuals were identified from 285 traps set in five habitat types (coral reef, octocoral hard-bottom, seagrass beds, algal plains and non-living substrate). The greatest number of observed traps were in algal plain (31%) and gorgonian habitat (27%), pointing to greater exploitation of deeper, non­ coral habitats. Coral habitat accounted for the most species trapped (41), whereas the mean number of fishes per trap was highest in algal plain (5.7, se=0.6). Six species made up 51% of all fish observed in traps. The Acanthuridae was the most abundant family. Species composition and number of fishes per trap were similar inside and outside park waters. Scarids and serranids were more frequently observed in traps inside the park. Between 1992 and 1994. patterns in the data emerged: smaller numbers of fish per trap; shifts to smaller size classes; fewer serranids, lutjanids, sparids, and balistids, and all feeding guilds except herbivores per trap; more acanthurids per trap. Compared with other trap data from the Virgin Islands and the Caribbean - Florida region, the mean number of fish and biomass per St. John trap are low, serranid numbers are low, and acanthurid and herbivore numbers are high. The reef-associated fishes of St. John appear to be overexploited.

The largest bacterium.

The large, morphologically peculiar microorganism Epulopiscium fishelsoni inhabits the intestinal tract of Acanthurus nigrofuscus, a brown surgeonfish (family Acanthuridae) from the Red Sea. Similar microorganisms have been found in surgeonfish species from the Great Barrier Reef. As these microorganisms have only been seen in surgeonfish and no free-living forms have been found, they are considered to be specific symbionts of surgeonfish, although the nature of the symbiosis is unclear. Initial reports considered them to be eukaryotic protists, based primarily on their size, with individuals being larger than 600 microns by 80 microns. But their cellular morphology in the electron microscope is more like that of bacterial than eukaryotic cells. To resolve the nature of these symbionts, we have isolated the genes encoding the small subunit ribosomal RNA from two morphotypes and used them in a phylogenetic analysis. In situ hybridization with oligonucleotide probes based on the cloned rRNA sequences confirmed the source of the rRNA genes. Our result identify the symbionts as members of the low-(G+C) Gram-positive group of bacteria. They are therefore the largest bacteria to be described so far.

Dead bleached coral provides new surfaces for dinoflagellates implicated in ciguatera fish poisonings

Dead sections of bleached corals in the United States Virgin Islands and British Virgin Islands were found to be colonized by filamentous algae harboring epiphytic dinoflagellates implicated in ciguatera fish poisonings. The dinoflagellates Ostreopsis lenticularis, Prorocentrum concavum, and P. lima were found in association with filamentous algae growing on dead sections of bleached Montastrea annularis and Acropora cervicornis. Several fish species from the families Acanthuridae, Pomacentridae, and Scaridae were observed to readily consume this filamentous algae/epiphytic dinoflagellate food source. Such fishes are common prey for large piscivores inhabiting tropical reefs. An increased incidence of ciguatoxic fishes may occur on reefs where bleaching events have caused significant coral mortality.

Analysis of Acanthurus triostegus for marine toxins by the stick enzyme immunoassay and mouse bioassay

The herbivorous convict tang or surgeon fish, Acanthurus triostegus, collected at different locations in the Hawaiian islands, was analyzed for toxicity using a mouse bioassay and a stick enzyme immunoassay (S-EIA) developed to detect ciguatoxin and closely related polyethers. Results of the S-EIA test indicated that about 94% of the samples gave negative readings, while 6% of the fish were positive and thus considered toxic. Fish samples from each location were pooled and the flesh and viscera were successively extracted with hexane, methanol, and water and tested in a mouse bioassay. About one-third of the methanol soluble fractions killed mice within 20 min, 70% killed within 4 hr, and 85% killed within 48 hr. About 40% of the hexane-soluble fractions killed mice within 24 hr and 55% killed within 48 hr. The water-soluble extracts of the flesh and viscera of fish taken from three locations showed relatively high toxicity. Common symptoms for all fractions included convulsions and jumping (especially just prior to death), respiratory distress, hind leg to complete paralysis, loss of body tone, and tremors. Analysis of the data suggests that in the flesh and viscera of A. triostegus there are at least three different nervous system-type toxins, most of which did not appear to react to the S-EIA test.

An unusual symbiont from the gut of surgeonfishes may be the largest known prokaryote

Symbionts first reported from the gut of a Red Sea surgeonfish, Acanthurus nigrofuscus (family Acanthuridae), were subsequently described as Epulopiscium fishelsoni. The taxonomic position of this very large (up to 576 microns in length) microorganism has previously been designated in the literature as either uncertain or eukaryotic. We suggest that similar symbionts from Great Barrier Reef surgeonfish may be prokaryotes, which together with E. fishelsoni from the Red Sea may represent the largest known forms of this cell type. Features identifying the symbionts as prokaryotes include the presence of bacterial-type flagella and a bacterial nucleoid and the absence of a nucleus or any other membrane-bound organelle.

A new species of Trichodina (Ciliophora: Peritrichia) from the intestine of the surgeonfish Acanthurus xanthopterus

A new species of Trichodina (Ciliophora: Peritrichia) from the intestine of the surgeonfish Acanthurus xanthopterus. International Journal for Parasitology 20: 785–787. A population of a trichodinid (Ciliophora: Peritrichia) was found in the gut of the surgeonfish Acanthurus xanthopterus collected from Hawaii, South Africa and New Guinea and described as a new species. This is only the second record of a trichodinid from the intestine of a marine fish. In all the fish specimens examined, the micro-fauna normally found in other species of the fish family Acanthuridae was absent and replaced entirely by the trichodinid population.

Occurrence and characteristics of unusual protistan symbionts from surgeonfishes (Acanthuridae) of the Great Barrier Reef, Australia

The occurrence of unusual symbiotic microorganisms was examined in the intestines of a range of fish from the Great Barrier Reef, Australia. The fish taxa examined included 26 species of the family Acanthuridae, as well as representatives of phylogenetically related and herbivorous taxa. The microorganisms, referred to as protists, were only found in herbivorous and detritivorous members of the Acanthuridae. Protists were not found in planktivorous acanthurids, nor in any members of the families Kyphosidae, Pomacentridae, Scaridae, Zanclidae, Siganidae and Bleniidae we examined. In addition, protists were absent from the herbivorous acanthurids A. xanthopterus and A. nigricans. A range of protist forms, characterized by differences in size (8 to 417 μm), shape and mode of cell division (daughter-cell production and binary fission), was observed. The occurrence of these forms appeared to be correlated with host feedingecology. Large forms (>100 μm) of the protists were only found in acanthurids which fed over hard-reef substrata. Smaller forms were found in sand-grazing and detritivorous species. One of the protist forms appears identical to protists previously reported from Red Sea acanthurids.

Comparative immunological, pharmacological and biological characteristics of ciguateric toxin found inCtenochaetussp. from Tahiti and Hawaii

Ciguatera poisoning is a seafood intoxication resulting from the consumption of certain reef fishes. The source of the toxin(s) has been identified as a dinoflagellate, Gambier‐discus toxicus, which was first discovered in the waters of the Gambier Islands in French Polynesia where ciguatera is considered to be a significant public health problem. The G. toxicus was subsequently found to occur in many parts of the world, including Hawaii. This paper is concerned with the immunological, pharmacological and biological characteristics of a ciguateric toxin found in two closely related surgeon fish (Ctenochaetus sp.) from Tahiti and Hawaii. The toxin extracted from the two groups of fish was found to be pharmacologically identical, but that from the Tahitian group was more toxic than that of the Hawaiian fishes based on enzyme immunassay and mouse bioassay.