Tuamotu Islands Research Articles

The role of mesoscale-driven connectivity patterns in coral recovery around Moorea and Tahiti, French Polynesia

Coral reefs are declining due to anthropogenic warming. Nonetheless, some have recovered quickly from repeated bleaching events. Coral recovery depends on adaptation capabilities, fishing pressure, overall number of stressors, reef conditions before the event, and degree of connectivity. Coral reefs that are connected to many others can receive viable larvae and regain coverage faster. Around Moorea and Tahiti, within the Society Islands of French Polynesia, coral cover has regained its previous levels rapidly, despite several mass bleaching events over the past three decades. Here it is explored whether the connectivity with distant reefs may support such recovery by modeling the transport of coral larvae around the islands over 28 years. Ocean currents enable connectivity with the Tuamotu Islands, ~ 250 km to the northeast, that act as sources to Moorea and Tahiti for pelagic larval durations of three weeks or longer. The circulation around Moorea and Tahiti is very dynamic; mesoscale eddies can also halt the connectivity with the Tuamotu Islands and sporadically transport larvae from reefs to the west and southeast instead. With many undisturbed coral reefs within a 300 km radius and strong mesoscale variability, a dynamic, long-range connectivity may explain the recovery of reefs around Moorea and Tahiti.

Taxonomic Insights into Caulerpa (Bryopsidales, Chlorophyta) Species in French Polynesia: Confirmation of 13 Species and Reinstatement of C. pickeringii Harvey & Bailey

Caulerpa J.V. Lamouroux is a genus of green macroalgae belonging to the family Caulerpaceae in the order Bryopsidales. The genus comprises 104 currently accepted species, of which 51 have been recorded from Pacific Islands. Among these islands, French Polynesia is found in the middle of the South Pacific Ocean and includes five archipelagos (i.e., the Austral, Gambier, Marquesas, Society, and Tuamotu Islands) where seaweed inventories have reported a total of 16 Caulerpa species so far based on morphology. Here, based on a sampling covering the five archipelagos of French Polynesia, we attempt to (i) verify the taxonomy of Caulerpa species present in these regions based on phylogeny, (ii) describe in more detail the specific diversity between the five archipelagos, and (iii) provide a morphological identification tool for these species. We successfully obtained 134 new tufA sequences for phylogenetic analyses, which corresponded to 13 species. We propose to resurrect C. pickeringii Harvey & Bailey for representatives of C. webbiana var. pickeringii and classify it in the Caulerpa subgenus Araucarioideae. We also transfer C. seuratii to C. pickeringii based on genetic results. A new morphological identification key is provided as well as an updated distribution of Caulerpa species across French Polynesia.

Holocene relative sea-level histories of far-field islands in the mid-Pacific

Holocene relative sea-level (RSL) data from far-field islands in the mid-Pacific have been used to validate the ice-melting histories of glacial isostatic adjustment (GIA) models. However, a lack of quality control in the reconstruction of RSL hinders the understanding of regional variability that can constrain ice-equivalent sea-level changes. Here, we present a standardised database of Holocene RSL data from five regions in the mid-Pacific (Cook Islands, Tuamotu Islands, Christmas (Kiritimati) Island, Gilbert Islands and Fiji). We categorised the data as high or low quality based on the susceptibility of samples to age and/or elevation errors. Of the 614 data points that were reviewed, 25% were rejected and 100 sea-level index points (SLIPs) were reinterpreted as limiting data. The new database consists of 141 SLIPs and 262 marine and 56 terrestrial limiting data points reconstructed from a variety of sea-level indicators (e.g., coral microatolls, mangrove peat, beachrock, and beach ridges), of which 71% provide high-quality constraints on RSL. The early to mid Holocene RSL evolution in the Cook Islands, Gilbert Islands and Fiji are poorly constrained due to a lack of high-quality SLIPs and limiting data during this period. The Tuamotu Islands provided the only record of early to mid Holocene evolution of RSL, indicating rapid RSL rise from between −22.9 m and −15.2 m at ∼9.0 ka to between −0.2 m and 0.5 m by ∼6.5 ka, at rates as high as 9.8 ± 5.1 mm/a, with a slowdown in the rate of RSL rise sometime between ∼8.2 ka and ∼6 ka. The Christmas (Kiritimati) Island record indicates stable RSL within ∼1.5 m of present-day levels over the past ∼6.6 ka. In the late Holocene, the Cook Islands record suggests a gradual fall in RSL over the past ∼2.9 ka at rates below 0.1 ± 4.3 mm/a. SLIPs at Fiji also indicate a slight fall in RSL at rates of less than 0.5 ± ∼4.4 mm/a at ∼4 ka, following which RSL fell from above 0.9 m at ∼3 ka to between −0.3 m and 0.6 m by ∼2.5– ∼2.1 ka. We highlight the importance of standardisation and quality control to critically evaluate the processes controlling RSL and validate GIA models. Indeed, the new standardised database has implications for the timing of the mid- Holocene highstand, which has been used to support the ICE-4G and ICE-7G_NA models. Due to the poor constraints of data in the mid-Pacific islands, particularly in the early Holocene, there remains no unique solution for a global ice-melting history.

Caulerpa Bikinensis (Chlorophyta) Preference for the Mesophotic Depths of Pacific Atolls1

The marine green alga Caulerpa bikinensis W. R. Taylor was described as a new species in 1950 from dredged specimens (37–57 m depth) from Bikini Atoll and Rongelap Atoll in the Marshall Islands. Its relative rareness in collections from waters less than 30 m deep from these atolls indicated that it favored the mesophotic coral ecosystem (MCE) at depths of 30–150 m. Published and unpublished records of this species over the past 70 years show its habitat preference on the seaward slopes of atolls and in lagoons. Observations were based on collections from Pacific atolls of the Marshall Islands, Tuamotu Islands, Chuuk State in the Federated States of Micronesia, Cook Islands, and Johnston Atoll, and on the deep lagoonal reefs of Palau. Caulerpa bikinensis has also been recorded in shallow waters 1 m deep in dark microcavities on lagoonal pinnacles at Takapoto Atoll (Tuamotu Islands) and in Chuuk Lagoon, and 2 m deep at Raroia Atoll (Tuamotu Islands). Caulerpa bikinensis favors the deeper depths of the MCE for its low light intensity rather than its cooler temperature, and definitely shows a strong affinity to the high energy seaward slopes of calcareous Pacific atolls.

The mode and timing of windward reef-island accretion in relation with Holocene sea-level change: A case study from Takapoto Atoll, French Polynesia

Takapoto Atoll (northern Tuamotu Islands, French Polynesia, Central Pacific) was selected as a test area to clarify the conditions of atoll island accretion in relation to mid- to late-Holocene sea-level changes. Surveys were conducted along two distinct cross-island profiles, on the windward coast of the atoll. In addition, the stratigraphy of an ocean-facing islet was described from an excavation in order to reconstruct the successive island accretionary stages.At both sites, the basement of the atoll-rims consists of conglomerate pavements on which lie shingle ridges, reaching 4 m in elevation. Stratigraphic analysis of the excavated ridge reveals alternation of gravelly sand-supported to gravel-dominated sediments. The chronology of island accretion is based on dating of 41 U/Th surface and excavated coral specimens. Ridge initiation occurred from about 1000 yr BP when sea level was close to its present position, shingle deposits progressively prograded from the lagoon margins oceanwards and were partially cemented at their bases. Cementation may have increased the resistance of the islets to erosion. As a result, some island lands accumulated and have persisted over the last millennium. The modern gross island morphology was acquired during the last 500 years. This model can be considered to be of regional value for the northern Tuamotu islands, adjusted for local thermal subsidence, hydroisostasy and/or lithospheric flexure.Compared to some other Indo-Pacific reef islands, island initiation at Takapoto appears to be have been delayed by 2 to 4 millennia, probably in response to retardation in the reef catching-up with mid-Holocene sea level. Dating of individual coarse-grained coral clasts allowed the major wave-surge events that have hit Takapoto to be identified for the last millennium. The use of gravels results in the identification of a greater number of medium-energy surge impacts, when compared with megaclast-based records. The frequency of storm events identified is consistent with that derived from historical observations; severe storms have a very low frequency of occurrence – one to two events per century on average.

Checklist of the terrestrial and freshwater arthropods of French Polynesia (Chelicerata; Myriapoda; Crustacea; Hexapoda)

ABSTRACT An annotated checklist for the terrestrial and freshwater arthropods of French Polynesia is presented. Compiled with the help of 48 experts and based on published records, it comprises 3025 valid species names belonging to the classes of Hexapoda Blainville, 1816 (2556 species), Chelicerata Heymons, 1901 (367 species), Myriapoda Latreille, 1802 (22 species) and Crustacea Pennant, 1777 (80 species). Reported are 1841 taxa from the Society Islands, followed by the Marquesas Islands with 1198 taxa, the Austral Islands with 609 taxa, the Tuamotu Islands with 231 taxa and the Gambier Islands with 186 taxa. The specificity of this fauna and the analysis of each class and order are discussed. The level of endemism is particularly high, 61% of the known species, with non-native species representing 13% of the overall species count. The threats to the native fauna and flora of French Polynesia and particularly to endemic insect species are detailed.

Exploring religious practices on Polynesian atolls: A comprehensive architectural approach towards the marae complex in the Tuamotu Islands

The archaeology of the Tuamotu Islands in central East Polynesia mainly derives from studies of ritual architecture. Since the pioneering works of Kenneth P. Emory in the 1930s, around 650 'marae' have been recorded in the archipelago. Surface inventories show that the basic architectural features of 'marae' were organised in a diversity of patterns, which reflect the complex histories of local communities. To investigate the variability of these monuments, a taxonomic classification of these 'marae' sites was developed, the first geographically extensive analysis of its kind. Relying on archaeological and ethnohistorical evidence, in addition to oral traditions, an attempt is made here to explain the development of these sites, considering endogenous sociopolitical processes, ritual innovations and external influences.

Indigenous language revitalization, promotion, and education: function of digital technology

ABSTRACTWithin the last two decades, there has been increased interest in how technology supports Indigenous language revitalization and reclamation efforts. This paper considers the effect technology has on Indigenous language learning and teaching, while conceptualizing how language educators, speakers, learners, and technology users holistically understand, skillfully apply and communicate creative and balanced technological solutions that are based on understanding of contextual factors. A total of 80 participants representing at least 47 Indigenous languages completed a survey in 2009 representing individuals, organizations, and institutions that serve one or more Indigenous language communities across the United States, Canada, Australia, New Zealand, Taiwan, Guatemala, Peru, Greenland, Mexico, Bolivia, French Polynesia (Marquesas Islands and Tuamotu Islands), and Russia. The data reveal the functions digital technology has in Indigenous language revitalization, which include (1) positive and supportive roles (2) concerns, constraints, and tensions, and (3) Indigenous language education. Regardless of the size of the community, opportunities for using technology in Indigenous language revitalization efforts are shaped by linguistic, cultural, social, economic, environmental, and technological factors as expressed in the technacy framework for language revitalization. Findings indicate that technology has wide and mostly positive applications in language learning and teaching, that the benefits of those applications remain consistent across communities regardless of size and geographic location, and that new and innovative uses of technology are being adopted to support language revitalization efforts. Overall, the study underscores the importance of context in making grounded decisions about technology as a component of contemporary language revitalization efforts.

Reefs at the edge: coral community structure around Rapa, southernmost French Polynesia

Rapa (27°36′ S, 144°20′ W) is a small (~40 km2) volcanic island isolated in the Southern Austral Archipelago, where direct anthropogenic stressors are extremely limited. Here, we present the results of the first quantitative survey of coral community structure across habitats and depths around the island. Despite its geographical isolation in the depauperate South Central Pacific, its small size and unfavourable environmental conditions (competition with macroalgae, low sea surface temperatures, reduced reef accretion), the diversity of scleractinian corals at Rapa is particularly high (112 species from 32 genera, including 37 species of Acropora) in comparison to other French Polynesian islands and subtropical Pacific locations. Our results indicate that the abundance (>100 colonies per 10 m2 recorded at nine of the 17 sampling stations) and cover (>40% at four stations) of corals are relatively high for a marginal reef location. Strong spatial heterogeneity was found, with high variation in diversity, abundance, cover and community composition among stations. Variation in community composition was related to habitat types, with distinct assemblages among fringing reefs within bays, reef formations at bay entrances, and those on the submerged platform surrounding the island. On the platform, a depth gradient was detected, with generic richness, abundance and cover generally greater at deeper stations (18–20 m depth) compared with medium-depth (10–12 m) and shallow (1–3 m) stations. A gradient was also recorded along bays, with increasing coral diversity and abundance from the bay heads to the bay entrances. The coral community at Rapa was characterized by the presence of several taxa not found in other French Polynesian archipelagos and the rarity of others that are common and abundant in the Society and the Tuamotu islands. Another distinctive feature of reef communities at Rapa is the high cover and dominance of macroalgae, particularly in the shallower parts of the surrounding platform, which probably explains the lower densities of coral colonies recorded there. These characteristics of the diversity and biogeographical composition of coral assemblages at Rapa provide considerable ecological grounds for its conservation.

Two new species and new records of Microprosthema Stimpson, 1860 (Crustacea: Decapoda: Stenopodidea: Spongicolidae) from the Indo-West Pacific.

Two new species of the spongicolid shrimp genus Microprosthema Stimpson, 1860 are described and illustrated on the basis of material collected recently in Australia and Japan. Type specimens of Microprosthema ningaloo sp. nov. were collected on Ningaloo Reef, Western Australia, whereas type specimens of Microprosthema pallidum sp. nov. were collected on a coral reef off Ishigaki Island, Ryukyu Archipelago, southern Japan. Microprosthema ningaloo sp. nov. and M. pallidum sp. nov. differ from all other species of the genus by a combination of morphological characters, including the gill-exopod formulae, and by their diagnostic colour patterns. This study increases the total number of species described in the genus Microprosthema to 16, nine of them in the Indo-West Pacific. In addition, new records are provided for M. lubricum Saito & Okuno, 2011 (Guam), M. plumicorne (Richters, 1880) (Red Sea, Mariana and Marshall Islands, French Polynesia), M. scabricaudatum (Richters, 1880) (Red Sea, Glorieuses and Tuamotu Islands), and M. validum Stimpson, 1860 (Red Sea, Madagascar, Singapore, French Polynesia), significantly extending their previously known distribution ranges.

Living Brachiopods from French Polynesia, Central Pacific, with Descriptions of Two New Species

Six species of recent brachiopods have been identified in material collected during the French Tarasoc Expedition to the Tarava Seamounts and the Society and Tuamotu Islands, French Polynesia, in 2009. Two of them, Frenulina sanguinolenta (Gmelin, 1790) and Thecidellina maxilla (Hedley, 1899), have already been reported from the studied region. Two species, Discradisca sparselineata (Dall, 1920) and Septicollarina zezinae Bitner, 2009, are reported for the first time from French Polynesia, and two other species are described as new, Dallithyris tahitiensis Bitner, n. sp., and Annuloplatidia curiosa Bitner, n. sp., although the latter species was already recorded from French Polynesia, ascribed to a different taxon. When compared with the brachiopod fauna from the southwestern Pacific, that of French Polynesia is taxonomically depauperate, which might reflect the younger geological age of the islands of the central Pacific.

Tonnoidean gastropods of French Polynesia

The tonnoidean gastropod fauna of French Polynesia (54 species) includes 26 species recorded from the Austral Islands (including 10 from Rapa), 33 species from the Marquesas Islands, 39 from the Society Islands, 32 from the Tuamotu Islands, and 3 from the Tarava Seamounts. Most species have planktotrophic larval development and are distributed from East Africa to eastern Polynesia, but many common western Pacific species are not present. With the possible exception of Semicassis salmonea n. sp. (Cassidae), described from the Marquesas, and Gyrineum pusillum (Ranellidae), restricted to the Austral (and Tuamotu?) Islands in southeastern-most Polynesia, no species is endemic to any individual island groups, but several species with broad overall ranges are known from only one archipelago within French Polynesia. Three species (Monoplex intermedius, Septa peasei, Ranellidae; Distorsio graceiellae, Personidae) are much more common in the Marquesas Islands than further westwards. Three species of Bursidae (Bursa lamarckii, Bursina nobilis, Tutufa tenuigranosa) are recorded only from the Marquesas Islands, whereas the only record of Bursina fijiensis is from the Austral Islands. The two very similar species Bursa asperrima and B. cruentata have a complex distribution; only B. cruentata is common west of Hawaii, and only B. asperrima occurs east of Hawaii, but only B. cruentata has been collected at the Marquesas Islands. Ranella venustula is a synonym of Bursa rhodostoma. Neotypes are designated for Buccinum ponderosum Gmelin, 1791, B. nodulosum Gmelin, 1791, Cassis caputequinum Röding, 1798, C. denticulata Röding, 1798, C. glabra Röding, 1798, C. hamata Röding, 1798, Phalium edentulum Link, 1807, P. quadratum Link, 1807, Buccinum biarmatum Dillwyn, 1817, B. pantherina Dillwyn, 1817, Cassis tenuilabris Menke, 1828, and Dolium rufum Blainville, 1829, and lectotypes are designated for Buccinum cornutum Linnaeus, 1758, Murex bufonius Gmelin, 1791 and Cassis torquata Reeve, 1848.

On two snapping shrimps, Alpheus baccheti n. sp. and A. coetivensis Coutière from the Tuamotu Islands, French Polynesia (Crustacea, Decapoda)

The present study deals with two species of the snapping shrimp genus Alpheus Fabricius, 1798 recently collected on a shallow reef flat of Makemo, central Tuamotu Islands, French Polynesia. Alpheus baccheti n. sp., is described on the basis of a single complete male specimen (holotype). The new species appears to be most closely related to the species of the A. lobidens de Haan, 1849 and A. strenuus Dana, 1852 species complexes, but can be easily distinguished from all of them by the presence of a distoventral tooth on the merus of the third and fourth pereiopods. The presence of Alpheus coetivensis Coutière, 1908 in the Tuamotu Islands is confirmed on the basis of several specimens from Makemo; some taxonomic remarks are provided for this species. The diagnostic colour patterns are illustrated for both A. baccheti n. sp. and A. coetivensis.

Rhodobium pfennigii sp. nov., a phototrophic purple non-sulfur bacterium with unusual bacteriochlorophyll a antennae, isolated from a brackish microbial mat on Rangiroa atoll, French Polynesia

A novel budding purple non-sulfur bacterium (strain AR2102(T)) was isolated in pure culture from a microbial mat that had developed in brackish-water ponds on the coral rim of the atoll of Rangiroa (Tuamotu Islands, French Polynesia). Single cells of this strain were rod-shaped and motile by means of polar flagella and divided by budding. Their intracellular photosynthetic membranes were of the lamellar type. Bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series, with spirilloxanthin as the main carotenoid, were present as photosynthetic pigments. Bacteriochlorophyll a absorption in the infrared portion of the light spectrum exhibited an unusual in vivo absorption peak at 909 nm. The strain grew optimally under photoheterotrophic conditions, but could grow photolithotrophically on thiosulfate or chemo-organotrophically under micro-oxic conditions. Optimal growth occurred in the presence of 1-2 % NaCl. Comparative sequence analysis of the 16S rRNA gene placed strain AR2102(T) within the class Alphaproteobacteria, in a cluster with Rhodobium species. Representatives of this cluster form a closely related group of slightly to moderately halotolerant to halophilic, rod-shaped, purple non-sulfur bacteria that divide by budding. The new isolate exhibited some differences in physiology (no utilization of alcohols or carbohydrates) and genetic characteristics (low relatedness in DNA-DNA hybridization) as well as in its relation to light (differences in absorption wavelengths) from previously described Rhodobium species. Consequently, we propose that strain AR2102(T) (=DSM 17143(T)=ATCC BAA-1145(T)) should be considered as the type strain of a novel species within the genus Rhodobium, Rhodobium pfennigii sp. nov.

Phylogeography of Eastern Polynesian sandalwood (Santalum insulare), an endangered tree species from the Pacific: a study based on chloroplast microsatellites

AbstractAim Patterns of genetic variation within forest species are poorly documented in island ecosystems. The distribution of molecular variation for Santalum insulare, an endangered tree species endemic to the islands of eastern Polynesia, was analysed using chloroplast microsatellite markers. The aims were to quantify the genetic diversity; to assess the genetic structure; and to analyse the geographical distribution of the diversity within and between archipelagoes. The ultimate goal was to pre‐define evolutionary significant units (ESUs) for conservation and restoration programmes of this species, which constitutes a natural resource on small, isolated islands.Location Eleven populations, each representative of one island, covering most of the natural occurrence of S. insulare were sampled: five populations from the Marquesas Archipelago; three from the Society Archipelago; and three from the Cook–Austral Archipelago. These South Pacific islands are known for their high degree of plant endemism, and for their human occupation by Polynesian migrations. The extensive exploitation of sandalwood by Europeans nearly 200 years ago for its fragrant heartwood, used overseas in incense, carving and essential oil production for perfume, has dramatically reduced the population size of this species.Methods We used chloroplast microsatellites, which provide useful information in phylogeographical forest tree analyses. They are maternally inherited in most angiosperms and present high polymorphism. Among the 499 individuals sampled, 345 were genotyped successfully. Classical models of population genetics were used to assess diversity parameters and phylogenetic relationships between populations.Results Four microsatellite primers showed 16 alleles and their combinations provided 17 chlorotypes, of which four exhibited a frequency > 10% in the total population. The gene diversity index was high for the total population (He = 0.82) and varied among archipelagoes from He = 0.40 to 0.67. Genetic structure is characterized by high levels of differentiation between archipelagoes (36% of total variation) and between islands, but differentiation between islands varied according to archipelago. The relationship between genetic and geographical distance confirms the low gene flow between archipelagoes. The minimum spanning tree of chlorotypes exhibits three clusters corresponding to the geographical distribution in the three main archipelagoes.Main conclusions The high level of diversity within the species was explained by an ancient presence on and around the hotspot traces currently occupied by young islands. Diversity in the species has enabled survival in a range of habitats. Relationships between islands show that the Cook–Austral chlorotype cluster constitutes a link between the Marquesas and the Society Islands. This can be explained by the evolution of the island systems over millions of years, and extinction of intermediary populations on the Tuamotu Islands following subsidence there. Based on the unrooted neighbour‐joining tree and on the genetic structure, we propose four ESUs to guide the conservation and population restoration of Polynesian Sandalwood: the Society Archipelago; the Marquesas Archipelago; Raivavae Island; and Rapa Island.

Threat of Invasive Alien Plants to Native Flora and Forest Vegetation of Eastern Polynesia

Eastern Polynesia, a phytogeographical subregion of Polynesia in the Pacific Ocean, comprises the archipelagoes of the Cook Islands, the Austral Islands, the Society Islands, the Tuamotu Islands, the Marquesas Islands, the Gambier Islands, the Pitcairn Islands, and Rapa Nui, which is the easternmost inhabited island of Polynesia. It consists of a total of about 140 tropical to subtropical oceanic islands that are among the most remote in the world, being over 3,000 km distant from the nearest continents. Because of this strong geographic isolation, the relatively young geological age, and small terrestrial surface (less than 4,000 km2) of these islands, the native flora of eastern Polynesia is impoverished, disharmonic, and with a relative low number of endemic genera (12). However, some high volcanic islands within these archipelagoes display a great diversity of habitats and a highly endemic flora (e.g., 50% for the vascular plants in Nuku Hiva, 45% in Tahiti) with striking cases of adaptative radiation (e.g., in the genera Bidens, Cyrtandra, Glochidion, Myrsine, and Psychotria). Most of these endemic taxa are restricted to montane rain forests and cloud forests. These upland wet forests are not directly threatened by habitat destruction by humans or disturbance by large mammals but rather by invasive alien plants. Native forests of eastern Polynesian islands are invaded by aggressive introduced species (e.g., Lantana camara and Psidium cattleianum in most island groups; Syzygium jambos in Pitcairn, Tahiti, and Nuku Hiva; Ardisia elliptica, Cestrum nocturnum, Spathodea campanulata in Tahiti and Rarotonga; Rubus rosifolius in the Society Islands, Hiva Oa, and Rapa Iti). Therefore, one of the highest priorities for the long-term conservation of the original native flora and forest vegetation of eastern Polynesia should be given to the study (invasion dynamics and ecological impacts) and control (strategy and methods) of the current invasive alien plants and to the early detection and eradication of potential plant invaders. Eastern Polynesia, with its small, diverse, and isolated oceanic islands, also offers opportunities to test hypotheses on the vulnerability of islands to invasion by alien species, with or without disturbance.

Local completion of the pelagic larval stage of coastal fishes in coral-reef lagoons of the Society and Tuamotu Islands

In four lagoons at two atolls and one high island in the Tuamotu and Society Islands, French Polynesia, plankton samples were taken weekly during 4 weeks in January/February 1989. A third atoll lagoon was sampled once. The lagoons varied in size and physical openness. We also sampled in the ocean near two atolls and the high island. All locations were sampled during the day, and three lagoons (two atolls and one high island) were also sampled at night. Pelagic fish eggs were more abundant in the ocean than in the lagoons at the atolls, but not at the high island. Larvae of coastal fishes were abundant in all lagoons. In the atoll lagoons, larvae of oceanic fishes were very rare to absent, but in the high-island lagoons and in the ocean, they were commonly encountered. In the ocean, larvae of many typical reef-fish taxa were abundant (58 taxa were represented by at least 10 individuals), but in the lagoons, most of these were rare or absent, and we conclude that these rare and absent taxa normally do not complete their larval phase in lagoons.

A new genus of small coral-reef goby (Teleostei: Gobiidae) from the Indo-west Pacific, with discussion of its relationships

A new genus and species, Minysicya caudimaculata, is created for a small coral reef gobiine known so far from the Yaeyama Islands, Ryukyu Archipelago, Japan; Scott Reef off northern Western Australia; Lizard Island, Queensland; and the Tuamotu Islands, French Polynesia. Phylogenetic analysis shows that Minysicya n. gen. forms a monophyletic group with five other genera including Bryaninops and Pleurosicya (commensal on various invertebrates and plants), but has fewer of the specialisations exhibited by the other genera.

Ambient temperature effects on the extrinsic incubation period ofWuchereria bancroftiinAedes polynesiensis: implications for filariasis transmission dynamics and distribution in French Polynesia

Temperature effects on development of the human filarial parasite Wuchereria bancrofti (Cobbold) (Filaridea: Onchocercidae) in the main Pacific vector Aedes polynesiensis Marks (Diptera: Culicidae) are analysed in relation to ambient climatic conditions. A statistical model of the extrinsic cycle duration as a function of temperature is described and used to distinguish three patterns of W. bancrofti transmission dynamics: continuous, fluctuating and discontinuous, occurring from north to south geographically among French Polynesian archipelagos. In the northerly Marquesas Islands (8-11 degrees S) filariasis transmission is continuous and very active, facilitated by perennially high temperatures combined with constantly high rates of man-vector contact. In the southerly Australes Islands (21-28 degrees S) filariasis transmission is seasonally discontinuous and, during the cooler months (May-September), the model predicts virtually no transmission because the cycle duration exceeds the life expectancy of the vector. In the Society Islands (16-18 degrees S), between the Marquesas and Australes, transmission is predicted to be intermediate as expected from their latitude, with seasonally fluctuating transmission potential. In the Tuamotu Islands (also geographically intermediate: 14-23 degrees S), with theoretically perennial transmission potential, transmission occurs only intermittently, being limited by other human and environmental factors whereby man-vector contact is confined to seasonal agricultural situations. Generally, among French Polynesian archipelagos where Aedes polynesiensis is the vector, the transmission potential for W. bancrofti and resulting disease manifestations of lymphatic filariasis in humans are correlated with ambient temperature due to the degree of southern latitude.

Behaviour of pelagic larvae of four coral-reef fish species in the ocean and an atoll lagoon

In-situ behaviour of settlement-stage larvae (10–30 mm) of four coral-reef fishes – Acanthurus triostegus, Chromis viridis, Neoniphon argenteus and Ptereleotris sp. – differed between lagoon and ocean at Rangiroa Atoll, Tuamotu Islands, French Polynesia. Divers released 130 larvae individually in midwater, and recorded larval swimming speed, depth and direction. All species swam faster than average currents, and C. viridis swam faster in the lagoon than in the ocean. Vertical distribution behaviour of all species differed between ocean and lagoon, generally by larvae swimming deeper in the ocean. Nearly all individual larvae swam directionally. Within a species, distribution of average bearings of individual larvae was not directional, nor did it differ between ocean and lagoon. Larvae detected predators 3–6 m away, and stopped or changed depth or direction to avoid them. We therefore reject the 'simplifying assumptions' that reef-fish larvae are passive or that their behaviour is independent of location. Behavioural flexibility of settlement-stage reef-fish larvae has implications for dispersal, retention and population connectivity. This constitutes the first report of larval reef-fish behaviour in the open ocean. However, in the ocean, many larvae descended rapidly below safe diving depth, and adult remoras interfered, making in-situ study of larval behaviour difficult.