Clarion Island Research Articles

Variations in inter-specific and sex-related niche partitioning in pelagic boobies during their annual cycle.

Animals that co-occur in a region (sympatry) may share the same environment (syntopy), and niche differentiation is expected among closely related species competing for resources. The masked booby (Sula dactylatra) and smaller congeneric red-footed booby (Sula sula) share breeding grounds. In addition to the inter-specific size difference, females of both species are also larger than the respective males (reversed sexual size dimorphism). Although both boobies consume similar prey, sometimes in mixed-species flocks, each species and sex may specialize in terms of their diet or foraging habitats. We examined inter- and intra-specific differences in isotopic values (δ13C and δ15N) in these pelagically feeding booby species during the incubation period at Clarion Island, Mexico, to quantify the degrees of inter- and intra-specific niche partitioning throughout the annual cycle. During incubation, both species preyed mainly on flyingfish and squid, but masked boobies had heavier food loads than red-footed boobies. There was no overlap in isotopic niches between masked and red-footed boobies during breeding (determined from whole blood), but there was slight overlap during the non-breeding period (determined from body feathers). Female masked boobies had a higher trophic position than conspecific males during breeding; however, no such pattern was detected in red-footed boobies. These results provide evidence of inter- and intra-specific niche partitioning in these tropical seabird species, particularly during the breeding period and in the more-dimorphic species. Our results suggest that these closely related species use different strategies to cope with the same tropical marine environment.

La investigación bioacústica de las aves del Archipiélago de Revillagigedo: un reporte de avance

Las canciones de las aves se han convertido en herramientas importantes para estudios taxonómicos, de ecología del comportamiento y de selección sexual. En esta contribución presentamos y comparamos las vocalizaciones de 12 especies de aves de las islas Socorro y Clarión del Archipiélago de Revillagigedo. Mostramos espectros sonoros de algunas vocalizaciones, así como una discusión de sus características y diferencias geográficas – a nivel de deme, subespecie o especie. Comparamos las vocalizaciones de algunas aves con aquéllas de sus contrapartes continentales. Documentamos algunos eventos acústicos relevantes, como son las vocalizaciones de las hembras de algunas especies, los duetos antifonales de la matraquita de Isla Socorro, o las contravocalizaciones que los cenzontles de Isla Socorro intercambian con sus vecinos al amanecer o al anochecer. Además, discutimos la aplicación de los cantos y las llamadas de algunas especies en tareas de conservación, tales como el levantamiento de censos poblacionales, la identificación de sexos o el recuento de individuos célibes o apareados. También proponemos algunas líneas que la investigación bioacústica en esta región insular pudiera tomar en el futuro.

First detection of an ocellate octopus in the Revillagigedos ecoregion, a biodiversity hotspot located in the Tropical East Pacific Province.

The biodiversity of mollusks, particularly cephalopods, has not been exhaustively determined in the Revillagigedos ecoregion, which is a biodiversity hotspot for several marine groups located in the Tropical East Pacific Province. In our study, we detected and examined ocellate octopuses from Socorro and Clarion Islands, and determined their identity using morphological criteria and molecular data from two mitochondrial genes (COIII and COI). The taxon identified was Octopus oculifer, a species considered endemic to the Galapagos Archipelago. In addition, according to our analyses, O. mimus, O. hubbsorum and O. oculifer are very closely related and may represent a species complex comprised of three morphotypes. We found that the evolutionary relationships among octopuses are not determined by the presence of ocelli. This study is the first to report a clade represented by ocellate and non-ocellate species, in addition, the identity of cephalopods in the Revillagigedos was determined with analytical support.

Foraging ecology of a marine top predator in the Eastern Tropical Pacific over 3\xa0years with different ENSO phases

The El Niño Southern Oscillation (ENSO) is a recurrent climatic pattern with important ecological consequences for seabirds due to its impacts on the abundance and distribution of food resources. We investigated the effects of ENSO phases on the foraging ecology of a marine top predator at Clarion Island in the Eastern Tropical Pacific using GPS and time-depth recorder data and regurgitates from incubating masked boobies (Sula dactylatra) during 3 consecutive years. Foraging locations were recorded in 2016 (El Niño, one female, three males), 2017 (neutral; six females, nine males), and 2018 (La Niña; eight females, ten males). Local sea surface temperature (SST) and chlorophyll-a concentration (CHL) within the birds’ foraging range were compared among the 3 years. Regurgitates were collected opportunistically from 25 and 31 incubating adults in 2017 and 2018, respectively. Average local CHL and SST were similar among years (mean SST 25 °C; mean CHL 0.10 and of 0.09 mg m−3 in January and March, respectively). Masked boobies travelled a maximum of 66 ± 34 km from the colony. The maximum trip duration was 7.7 ± 3.4 h and total distance travelled during a foraging trip was 164 ± 73 km, with no sex- or year-related differences. Masked boobies mainly caught flying fish, but their diet also included one squid and six other fish families. In contrast to previously reported changes in foraging ecology of seabirds, masked boobies at Clarion Island seemed to be unaffected during El Niño, because the local oceanography was relatively unperturbed by ENSO oscillations.

FISHES OF ARCHIPELAGO OF REVILLAGIGEDO ISLANDS: A SYSTEMATIC AND BIOGEOGRAPHIC UPDATE

We present a comprehensive and update checklist systematic of the icthyofauna of this insular region, which is comprised by 366 species, 241 genera, 101 families, 28 orders and tree classes. The families with the most richness specific were: Carangidae (20 spp.), Serranidae (19) and Muraenidae (18). Socorro Island was recorded 220 species, Clarion Island 179, San Benedicto Island 128; followed by Roca Partida Island 62. This diversity as well as endemic species number is relationship with the surface of each island. There is a higher similarity ictiofaunistic between Clarion Island and Socorro Island; while, the lowest similarity was between San Benedicto Island and Roca Partida Island. The ichthyogeography of the Revillagigedo Archipelago has a higher affinity with the Panamic province (42.3%), followed by the Cortes (41.5%). A higher number of species are of the wide distribution (circumglobal: 21 %; amphipacific 22.4 %). Also, endemic species are represented by 26 species (7.1%).

Redescription of Mugil setosus Gilbert 1892 with comments on the occurrence of Mugil curema Valenciennes 1836 in the Pacific Ocean (Teleostei: Perciformes: Mugilidae).

Mugil setosus Gilbert 1892 was originally described by Gilbert based on specimens from Clarion Island, in the western and most remote of the Revillagigedo Islands, about 1,000 km off the western Pacific coast of Mexico. Examination of the type of material and recently collected specimens from Ecuador and Peru, resulted in the redescription provided herein. Diagnostic characters of the species were mainly: tip of the pelvic fin reaching beyond the vertical through the base of the third dorsal-fin spine, the pectoral-fin rays with ii+13-14 rays, the anterodorsal tip of second (soft) dorsal fin uniformly dark, and an external row of larger teeth, and more internally a patch of scattered smaller teeth, visible mainly in adults 150 mm SL. The expansion of geographic distribution of Mugil setosus and occurrence of Mugil curema Valenciennes 1836 in the Pacific Ocean are discussed.

First record of Petalidium suspiriosum Burkenroad, 1937 (Dendrobranchiata, Sergestidae) in the Gulf of California, Mexico

Abstract The pelagic shrimp Petalidium suspiriosum described from off Clarion Island, Mexico, in the eastern Pacific, is recorded for the first time in the Gulf of California. The unique male specimen was captured in deep water of the central Gulf of California. Diagnostic characters, including the petasma, are illustrated and briefly described.

Partial albinism in the Revillagigedo sea chub Kyphosus sectatrix (Perciformes: Kyphosidae) from Clarion Island, Mexico

Kyphosus sectatrix has a widespread distribution inhabiting rocky and coral reefs from warm waters around the world, from the West Pacific to the East Pacific (including the Revillagigedo Archipelago), the Indian Ocean, the Red Sea, the Atlantic and the Mediterranean. On March 2016, during an expedition to Clarion Island, Revillagigedo Archipelago, we observed an individual of K. sectatrix with abnormal body coloration, entirely white with black eyes, a condition known as partial albinism. This contrasts with the xanthic condition (entirely yellow or with black blotches) commonly observed in K. sectatrix at the Revillagigedo Archipelago. This specimen represents the first documented record of partial albinism in K. sectatrix for the Mexican Pacific.

Reproducción del rabijunco pico-rojo (Phaethon aethereus) en isla Clarión, México

El rabijunco de pico rojo se encuentra catalogado como una especie amenazada en México. Hay muy poca información de esta especie en el mundo. Entre enero-mayo de 2015 y 2016 confirmamos su anidación en la Isla Clarión (existían reportes y conteos de parejas volando alrededor de la isla, pero sin evidencia de nidos). Estimamos aproximadamente 48 parejas anidando en la isla. La temporada de reproducción ocurre entre los meses de diciembre y mayo. Al comparar nuestros datos con un reporte de parejas volando en 1990 parece que la población se ha mantenido relativamente estable en los últimos 25 años.

Two centuries of coherent decadal climate variability across the Pacific North American region

AbstractThe decadal variability of the Pacific Ocean and North American hydroclimate are subjects of immediate concern for society, yet the length of the instrumental record limits full mechanistic understanding of this variability. Here we introduce a 178 year, seasonally resolved coral oxygen isotopic record from Clarion Island (18°N, 115°W), a sampling a subtropical region that is strongly influenced by the decadal‐scale fluctuations of the North Pacific Gyre Oscillation and a region that serves as a critical locus for the communication of climate anomalies with the tropics. This Mexican Pacific coral record is highly correlated to coral records from the central tropical Pacific and tree ring records from western North America. Significant changes in the amplitude of oceanic decadal variability in the early nineteenth century are mirrored in the drought reconstructions in western North America. The spatial manifestation of this relationship was relatively invariant, despite notable changes in the climatic mean state.

Phylogenetic placement of the critically endangered Townsend’s Shearwater (Puffinus auricularis auricularis): evidence for its conspecific status with Newell’s Shearwater (Puffinus a. newelli) and a mismatch between genetic and phenotypic differentiation

Townsend’s Shearwater (Puffinus auricularis auricularis) is a highly threatened bird and currently breeds on Socorro and Clarion Islands, Mexico. This subspecies has minor differences in plumage patterns when compared to Newell’s Shearwater of Hawaii (USA) (Puffinus auricularis newelli). These two forms are recognized as subspecies by the American Ornithologist’s Union. However, some authors consider them as distinct species based on subtle plumage differences and different breeding chronologies. We used Bayesian and Maximum Likelihood methods to compare the cytochrome b and cytochrome oxidase I sequences from Townsend’s Shearwaters with archived mitochondrial sequences from other taxa in the genus Puffinus. Townsend’s and Newell’s Shearwaters show little genetic differentiation; hence, there is no justification to consider them as different species. Additionally, differences in morphology and ecology might be the result of founder effects and phenotypic plasticity; proven migratory potential provides support to the current taxonomic assessment that considers these birds as conspecifics. We recommend the continued treatment of Townsend’s and Newell’s Shearwaters as two subspecies of P. auricularis. We also advocate treating the Rapa Shearwater (P. myrtae) as a distinct species.

Birds of Clarion Island, Revillagigedo Archipelago, Mexico

Abstract We recorded 62 bird species on Clarion Island, Mexico (Revillagigedo Archipelago, Pacific Ocean) during 1998–2006, eight of which breed there, 52 are considered non-breeders, and breeding is likely but unconfirmed for the Red-billed Tropicbird (Phaethon aethereus), Nazca Booby (Sula granti), and an unidentified shearwater. Thirty species are new for the island. A census of the Clarion Burrowing Owl (Athene cunicularia rostrata) in 2002/03 suggested a maximum total population of ∼850 pairs. At least 46 pairs of Laysan Albatrosses (Phoebastria immutabilis) bred in 2002/03, but the species experienced total breeding failure during our study. This result was unexpected because feral pigs (Sus scrofa) were successfully eradicated from Clarion by 2002; endemic Clarion Ravens (Corvus corax clarionensis), an endemic snake (Clarion Racer, Masticophis anthonyi), and an unidentified ant were associated with egg and hatchling failures. A small colony of an unidentified shearwater could be a recolonization by...

Remarkable crickets from remarkable islands: (Orthoptera: Grylloidea: Gryllinae and Nemobiinae) from Anak Krakatau and Clarion islands)

A new nemobiine cricket from Anak Krakatau in the Sunda Strait (Pteronemobius krakatau n. sp.) and a new grylline from Clarion Island in the eastern Pacific (Gryllus alexanderi n. sp.) are illustrated and described.

Crystal Fractionation and the Evolution of Intra-plate hy-normative Igneous Suites: Insights from their Feldspars

Feldspars and normative feldspar constituents of bulk magma show complexes and ‘anorogenic’ granites, is associated with hotspot and continental rift environments. A major chartrends supportive of fractional crystallization in the three main types of hy-normative intraplate suites that contain qz-oversaturated acteristic of this magmatism is the production of suites of compositionally diverse rocks that are temporally and rocks: ocean island and continental alkalic suites, ocean island tholeiitic suites and continental tholeiitic suites. These suites are spatially associated. Much is still unknown about the processes that have led to the diversity of magmas within characterized by the presence of a single feldspar in each suite member, a shift of this feldspar from plagioclase to alkali feldspar, such suites or to the global diversity of intra-plate suite types. and K enrichment of alkali feldspar with decreasing temperature in the trachytic members. The modal feldspars provide evidence for a Many ocean island and continental hotspot (and continental rift) related suites are characterized by rocks with reaction relationship between feldspars and indicate a build-up of magmatic volatile content towards saturation with progressive high alkali/silica ratios that fall into the alkalic field of Irvine & Baragar (1971; Fig. 1) regardless of their state fractionation of a parental magma having low initial volatile content. The feldspar and normative feldspar evolutionary paths are unique of silica saturation. Such alkalic suites range from those that are strongly silica undersaturated, containing rocks for each of the three suite types but similar for different suites within the same type. This characteristic extends to the felsic members, such as nephelinites (or leucitites in the more potassic making it easy to distinguish between rhyolitic or granitic rocks suites), to mildly silica-undersaturated suites [the Kenfrom the different suite types. The feldspars in natural volcanic nedy series of Miyashiro (1978)] containing alkali basalts, suites commonly show evidence for a polybaric history, particularly silica-undersaturated trachytes and phonolites, and, in the least-evolved suite members. Late-stage feldspars of the finally, to hy-normative suites [the Coombs trend of intermediate members and feldspars of the most evolved members Miyashiro (1978)] that include olivine basalts, trachytes show paths indicative of significantly lower temperature and pressure and rhyolites. Hy-normative alkalic suites that contain regimes. silica-oversaturated rocks on ocean islands are widespread and include those from Ascension Island (e.g. Harris, 1983), the Samoan Islands (MacDonald, 1968), Terceira, Azores (e.g. White et al., 1979) and Clarion Island, Mexico

Geochemistry of deep‐sea surface sediments from the pacific manganese nodule province near clarion island, Mexico

Abstract Surface sediments from the Pacific oceanic area near Clarion Island, Mexico were studied. Microscopic observations show that the sediments are formed mainly by materials from submarine vulcanism, and biogenic, authigenic, and clay materials in different proportions according to the physiographic studied regions (the EPR region at 21°N, the high density nodule region (HDN), and an intermediate region). Compared to average Pacific pelagic clays, sediments are enriched in Mn and some trace metals, such as Ni, and Co in the studied area. The sediments show particular chemical characteristics that apparently reflect the processes taking place in each particular region. A cluster analysis of the chemical data shows the presence of 4 different geochemical groups, namely: Group 1 has characteristics associated to hydrothermal processes; Group 2 has a high hydrothermal influence, with the highest concentration of Zn in sediments; Group 3 corresponds to the north part of the high density nodule region and ...

PSOCOPTERA (INSECTA) OF SOCORRO AND CLARION ISLANDS, REVILLAGIGEDO ARCHIPELAGO, MEXICO, SPECIES AND COMPARISONS WITH THE CONTINENTAL AND THE TRES MARIAS ARCHIPELAGO PSOCID FAUNAS

Diecienueve especies de psócidos fueron registrados en Isla Socorro, con una superficie de 167 km^, y a 704 km al oeste de Manzanillo, Colima, México, y seis especies de psócidos fueron registrados en Isla Clarión, con una superficie de 25 km^ y a 372 km al oeste de Isla Socorro y a 1076 km al oeste de Manzanillo. Todas las especies de Clarión, excepto dos, se encuentran también en Socorro. Sólo dos de las 21 especies de ambas islas son endémicas: una de ellas se encuentra en ambas islas y la otra se encuentra sólo en Clarión; ambas son del género Cerobasis. la mayoría de las especies no endémicas se han registrado en la costa del Pacífico de México, al este de las islas. Siete de las 21 especies de las Islas Revillagigedo se encuentran también en las Islas Marías, y 13 de ellas se encuentran también en la costa del Pacífico de México, para dar un indice de similitud faunística de 0.19 con ambas áreas. la fauna de psócidos de las Islas Revillagigedo, constituye una extensión empobrecida de la fauna de psócidos de la costa del Pacífico de México, explicable por la distancia de la costa a las islas, y por el área reducida de éstas.

Notes from Clarion Island

Notes from Clarion Island

Geology and Petrology of Clarion Island, Mexico

Clarion Island is the westernmost of the four islands of the Revillagigedo group in the east Pacific. The Clarion Fracture Zone was named for this island, which is the first subaerial expression of the fracture zone as it approaches the Mexican mainland. The petrography and submarine topography indicate that the island is the summit of a submarine volcano. Five lithologic units recognized on Clarion Island appear to represent distinct eruptive or depositional phases in its evolution. The earliest eruptions took place along east-trending fractures which may be related to movements on the Clarion Fracture Zone, while later eruptions issued from north- or northeast-trending fractures, suggesting a late Cenozoic change in the regional stress pattern. The volcanic rocks are all members of the alkalic basalt-trachyte association typical of oceanic islands. Variation from the average of low-potash tholeiite from the East Pacific Rise through a well-defined basalt sequence (the Gallegos basalt) can be expressed by the equations ![Formula][1] suggesting an ultimate tholeiitic parentage for the alkalic basalt. Fractional crystallization of low-potash tholeiite, and possibly volatile diffusion of alkalis, are considered to be the major causes of differentiation. [1]: /embed/graphic-1.gif

Diurnal Fluctuation in Photosynthetic Rate and Chlorophyll “a” Content of Phytoplankton from Eastern Pacific Waters

Measurements were made of photosynthetic activity and chlorophyll “a” content of phytoplankton samples taken at regular intervals over a 46‐hour period in May 1957, from surface waters near Clarion Island in the eastern Pacific Ocean. Results confirm previous observations of a diurnal periodicity in photosynthesis which, in this particular instance, appears to be correlated with variations in chlorophyll content. The photosynthesis‐chlorophyll relationship gives an estimated value of 4.24 mg C/hr per mg of chlorophyll “a” at a light intensity of 1000 foot‐candles.

Notes on the Herpetology of the Revillagigedo Islands, Mexico

The Revillagigedo Archipelago consists of a group of four volcanic, oceanic islands located approximately 210 miles southwest of the tip of Baja California. They are located between 180 20' and 190 20' N. latitude and 1100 45' and 1140 50' W. longitude and are governed by the Mexican state of Colima. The islands, in order of increasing size, are Roca Partida, San Benedicto, Clarion, and Socorro. They are all uninhabited and there is no fresh water on any of the islands except a small stagnant well and some rock seeps on Socorro. The rainy season, according to Hanna (1926), probably occurs from September to December. The only resident vertebrates are birds, introduced sheep (on Socorro Island where they were left in 1867 and are present today only in small numbers), and three species of reptiles. No amphibians or freshwater fishes occur on the islands. No reptiles occur on Roca Partida or San Benedicto islands. The former is a small barren rock and the latter is a steep sided island four miles long and about 2 miles wide. It is on San Benedicto that a new volcano, Boqueron, first erupted in August of 1952 (Williams, 1952; Richards, in press). Clarion Island (6 by 4 miles) is covered with grass and thick clumps of Convolvulus-covered prickly pear cactus plus large areas of low shrubs, 5-6 feet high. Clarion island reaches, an elevation of 1,000 feet. Its herpetofauna consists of a racer, Masticophis anthonyi, a lizard, Urosaurus clarionensis, and two sea turtles, Caretta c. gigas and Chelonia mydas agassizi. Socorro Island (9 by 9 miles) reaches an elevation of 3,710 feet. The dominant vegetation of the west, south and east sides of the island consists of one species of low shrub and a prickly pear cactus. The north side of the island and the elevations above 2,000 feet are covered with broad-leaved tropical plants. The herpetofauna of Socorro consists of one species of lizard, Urosaurus auriculatus and one sea turtle, Chelonia mydas agassizi. The islands have been studied biologically only during short stops by major scientific expeditions. Most important of these were the Albatross Expedition (Townsend, 1890) and the California Academy of Sciences Expedition of 1925 (Hanna, 1926; Slevin, 1926). Other expeditions to the islands, as well as the complete history of the islands, can be found in Mares y Islas Mexicanos del Pacifico, Mexico, 1949. The reader is referred to Hanna (1926), Johnston (1931), McLellan (1926), Richards (MS), and Brattstrom and Howell (MS) for further descriptions of the islands, their plants, birds, and geology. In March of 1953, through the generosity of Scripps Institution of Oceanography, I had the opportunity of visiting the Revillagigedo Archipelago during a cruise undertaken primarily to study the geology and volcanology of the islands. The trip was led by Mr. Adrian Richards aboard the Research Ship Paolina-T, Robert Newbegin, Captain. The ship left San Diego on March 3