Pacific Science, vol. 67, no. 4 (2013)

Pac Sci 67.4 cover
Affinities of Sponges (Porifera) of the Marquesas and Society Islands, French Polynesia
Kathryn A. Hall, Patricia R. Sutcliffe, John N. A. Hooper, Aline Alencar, Jean Vacelet, Andrzej Pisera, Sylvain Petek, Eric Folcher, John Butscher, Joel Orempuller, Nicolas Maihota, and Cécile Debitus, 493

Abstract: This article reports on a survey of sponges from the higher-island reefs and slopes of the Marquesas and Society Islands archipelagos, French Polynesia, recording presence/absence and an estimate of local abundance at 109 sites from six and eight islands within each archipelago, respectively. Sponge distributions within archipelagos were relatively homogeneous, showing some differential patterns in affinities between north-south islands, and approximately one-third of the fauna apparently endemic to these archipelagos, but between-archipelago comparisons showed large heterogeneity, with only four of the 75 species shared between both archipelagos. The fauna of the Marquesas Islands (with sites consisting mostly of rocky slopes) was dominated by species in order Poecilosclerida and showed a range of taxonomic diversity similar to that of the remote fauna of the Hawaiian Islands. By comparison, the sponge fauna of the Society Islands sites was dominated by species of order Dictyoceratida, reflecting predominance of coral reef and lagoon sites and associated phototrophic feeding strategies. Parsimony and multivariate statistical analyses comparing French Polynesian sponge faunas with others in the southwestern Pacific showed closest nested faunal similarities between the (Marquesas Islands+Society Islands), (((Tonga+Fiji)+Vanuatu)+New Caledonia), and (North Great Barrier Reef+South Great Barrier Reef) but no or very low similarity between more geographically isolated faunas such as Palau and the collective Great Barrier Reef.

Evidence of an Island-Associated Population of False Killer Whales (Pseudorca crassidens) in the Northwestern Hawaiian Islands
Robin W. Baird, Erin M. Oleson, Jay Barlow, Allan D. Ligon, Antoinette M. Gorgone, and Sabre D. Mahaffy, 513

Abstract: Two populations of false killer whales, Pseudorca crassidens, are recognized from Hawaiian waters: the Hawaiian insular population, an island-associated population found around the main Hawaiian Islands; and the Hawai‘i pelagic population, found in offshore waters. This species has not been previously documented near the Northwestern Hawaiian Islands. During a 2010 large-vessel survey throughout the Exclusive Economic Zone (EEZ) surrounding the Hawaiian Islands, false killer whales from 11 encounters were individually photo-identified, and photos were compared among encounters and with a catalog of false killer whales from the main Hawaiian Islands. Individuals from three of the encounters, all in the Northwestern Hawaiian Islands within the eastern part of the Papahānaumokuākea Marine National Monument, were the only ones documented that matched with false killer whales previously seen around the main Hawaiian Islands, and the matches were to individuals documented off Kaua‘i in 2008 that were of unknown population membership. Two individuals from one of these three 2010 encounters were instrumented with satellite tags attached to dorsal fins, and their movements were documented over 4.6 and 52 days. Movements of the tagged individuals ranged from French Frigate Shoals to Middle Bank (between Nīhoa and Ni‘ihau) and included shallow nearshore waters and deep waters to 147 km from land. Combined, the photo-identification and satellite-tagging results suggest that there is a second island-associated population of this species in Hawai‘i that primarily uses the Northwestern Hawaiian Islands, with a range that overlaps with that of the main Hawaiian Islands insular population.

Entanglements of Large Cetaceans in Peru: Few Records but High Risk
Ignacio García-Godos, Koen Van Waerebeek, Joanna Alfaro-Shigueto, and Jeffrey C. Mangel, 523

Abstract: Entanglements of large cetaceans with fishing gears were only recorded four times in Peru before 1995, despite the intensive use of gill nets and longlines. This work compiles recent events of large cetacean entanglement in Peru, from direct observations, local news, and online graphical evidence. A total of 15 confirmed entanglements was recorded between 1995 and 2012, involving humpback whales, Megaptera novaeangliae (n=10); sperm whales, Physeter macrocephalus (n=3); an Antarctic minke whale, Balaenoptera bonaerensis; and an unidentified balaenopterid. Gill nets were involved in 80% of the entanglements, followed by longlines. Prevalence of humpback whale entanglements may be associated with the neritic location of the majority of gill net fishing sets, interfering with the whale’s migratory routes and reproductive habitat in northern Peru. Intensive use of gill nets and increasing use of longlines in artisanal fisheries represent serious threats to conservation of large cetaceans in Peru and the Southeast Pacific and need to be addressed by national and regional conservation authorities.

High Mortality in a Surgeonfish following an Exceptional Settlement Event
Adrian C. Stier, Joshua A. Idjadi, Shane W. Geange, and Jada-Simone S. White, 533

Abstract: Marine organisms occasionally settle at exceptional densities, whereby thousands of individuals arrive concurrently. High levels of mortality, which has historically been attributed to predation or competition, often follow this episodic settlement of reef fishes. Here, however, we observed large numbers of newly settled surgeonfish (Ctenochaetus striatus) with white lesions lying dead on the sand amongst patch reefs following separate episodic settlement events in 2006 and 2009 in Moorea, French Polynesia. Pathogens have been identified as an important driver of population dynamics in other marine organisms but less so for reef fishes. Our observations suggest that disease outbreaks may play an underappreciated role as a mechanism of mortality following episodic settlement events in reef fishes.

Food Availability for Particle-Feeding Bivalves, Anadara spp., in Fiji
Yousef A. E. S. M. Buhadi, Toru Kobari, Kei Kawai, Tomoko Yamamoto, Hiroshi Suzuki, Satoru Nishimura, Takashi Torii, and Joeli Veitayaki, 539

Abstract: We compared food availability of filter-feeding bivalves, Anadara spp., between two Fijian sites of different mangrove richness to evaluate impacts of environmental variables on Anadara spp. abundance and body size. Suspended particles including planktonic organisms and detritus were more abundant in the fishery grounds of the mangrove-rich site (MR) than in the mangrove-poor site (MP). Although no substantial difference was observed in abundance of Anadara spp., dry weights of soft tissue were heavier for animals at MR than those at MP. Respiration rates (i.e., minimum metabolic requirements) of Anadara spp. decreased with increasing animal weight. Unicellular planktonic biomass was estimated to support the Anadara community metabolic requirements (i.e., minimum food requirement) for 9.2 to 85.7 days at MR and 1.4 to 67.4 days at MP, indicating that the planktonic biomass cannot support sufficient growth of the bivalve population at some locations. These results suggest that suspended particles support increased shell sizes of Anadara spp. and that resuspended detritus is a supplement or alternative food resource for these bivalves in mangrove-coral associated ecosystems.

Herbarium Specimens Reveal Putative Insect Extinction on the Deforested Island of Mangareva (Gambier Archipelago, French Polynesia)
David H. Hembry, 553

Abstract: Human activities are expected to result in extinction of many organisms in taxonomically neglected lineages; however, actually documenting these extinctions is very difficult for soft-bodied organisms that do not leave a subfossil record. Subfossil and historic records reveal that human-induced extinction has been particularly marked for gastropods and terrestrial vertebrates on Pacific islands, but whether human activities resulted in similar biodiversity loss in soft-bodied, taxonomically neglected animals (such as insects) remains unclear. However, in cases in which specialized plant-feeding insects leave diagnostic feeding damage on plants, herbarium specimens coupled with resurvey efforts may indicate potential extinctions or extirpations during historic times. Here, I report the discovery of leaf mines in herbarium specimens of the plant Phyllanthus wilderi (Phyllanthaceae: Glochidion sensu lato) from the island of Mangareva (Gambier Islands, French Polynesia). These mines were not rediscovered in recent surveys on Mangareva but are similar to those made today by leaf-mining moths (Lepidoptera: Gracillariidae) on many other islands in southeastern Polynesia. This is, to the best of my knowledge, the first report of a potential insect extinction from Mangareva, an island already well known for its history of anthropogenic habitat destruction and biodiversity loss. This result indicates that herbarium specimens may be used to identify potentially extinct and extirpated insect taxa. Future biodiversity surveys on Pacific islands and elsewhere should use herbarium specimens as a guide both to documenting potential extinctions and to search for rediscovery of rare taxa.

Diversity and Origins of Fijian Leaf-Cutter Bees (Megachilidae)
Olivia K. Davies, Scott V. C. Groom, Hien T. Ngo, Mark I. Stevens, and Michael P. Schwarz, 561

Abstract: Bees are key pollinators in almost all terrestrial ecosystems and can have major roles in agricultural production. Records of bees in the Southwest Pacific indicate a very low diversity, with the Fijian bee fauna one of the least diverse, despite an otherwise rich biota. Megachilid bees represent a large proportion of the bee fauna for almost all island groups in the Southwest Pacific and, because they are wood- and stem-nesting, their wide distribution is likely to have been influenced by rafting and anthropogenic maritime trade. Our study is the first to apply molecular techniques to the study of megachilid bees in this region and indicates between four and five recent introductions to Fiji, likely from Southeast Asia. The study also provides the first record of Heriades (Michenerella) in the Southwest Pacific and the first record of the subgenus Megachile (Callomegachile) in Fiji. These results indicate that a large proportion of the Fijian bee fauna is likely to have been introduced only very recently and, therefore, has had only a very recent role in Fijian ecosystems, despite their current abundance. This has very wide implications for understanding Fijian plant-pollinator relationships. We argue that there is a strong need to understand ancient plant-pollinator relationships that may have evolved in Fiji before the mid–late Pleistocene and Holocene and whether these could be disrupted by recent bee introductions.

Terrestrial Herpetofauna of Île des Pins, New Caledonia, with an Emphasis on Its Surrounding Islands
Anthony J. Geneva, Aaron M. Bauer, Ross A. Sadlier, and Todd R. Jackman, 571

Abstract: New Caledonia is recognized globally as a biodiversity hot spot due, in part, to the high levels of endemism seen among the region’s unique fauna and flora. Although substantial research efforts have been dedicated to the remarkable reptile diversity of the main island, the Grande Terre, comparably few studies have focused on the Île des Pins that lies off its southern tip. The last review of the herpetofauna of the Île des Pins was 18 yr ago; since then increased effort has been directed toward investigating the reptiles of the Île des Pins and its satellite islands. In this update we provide an overview of this region’s lizard fauna, including new reptile records and the results of surveys of previously herpetologically unexplored islands in the vicinity of the Île des Pins, all in the context of a revised taxonomy. Results presented expand known ranges of 18 species and identify eight species not previously known from the area. Satellite islands surrounding the Île des Pins, despite their small size, contribute substantially to the biodiversity of the region and support several reptile species of conservation concern not recorded for the Île des Pins proper, nor the New Caledonian mainland.

Loss of Seed Buoyancy in Hibiscus glaber on the Oceanic Bonin Islands
Hiroshi Kudoh, Koji Takayama, and Naoki Kachi, 591

Abstract: The Bonin (Ogasawara) Islands are subtropical oceanic islands in the northwestern Pacific. Reflecting their ancient origins, previous studies on plants of the Bonin Islands reported evolutionary phenomena that are common to oceanic islands, such as high endemism and accelerated diversification. In this article, we demonstrate the first example of loss of seed dispersibility during the evolutionary processes of the plants of the Bonin Islands. Seed buoyancy and morphology of Hibiscus glaber, a tree endemic to the Bonin Islands, and H. tiliaceus, a pantropic species, were examined. The latter is the progenitor species of H. glaber. Average ratios of floating seeds per tree were 0.2 and 0.8 for H. glaber and H. tiliaceus, respectively, in a 3% NaCl solution. There was considerable variation among individual H. glaber trees, ranging from 0 to 0.89. The air space inside the seed coat was generally smaller in H. glaber than in H. tiliaceus. Loss of seed buoyancy in H. glaber is due to decreased air space in the seeds. It is plausible that loss of seed buoyancy occurred in response to the habitat shift inland during the speciation process of H. glaber from the coastal species H. tiliaceus.

Palau’s Rare and Threatened Palm Ponapea palauensis (Arecaceae): Population Density, Distribution, and Threat Assessment
Craig M. Costion, Ann Hillmann-Kitalong, Steve Perlman, and Will Edwards, 599

Abstract: Ponapea palauensis Kaneh., a palm endemic to the Palau archipelago in the western Caroline Islands, has previously been reported to be threatened and in decline due to predation by two species of introduced parrots, Cactua galerita Lath. and Eclectus roratus P. L. S. Mull., and potential predation by introduced rats. Here we assess its threatened status under the IUCN Red List Criteria and provide the first quantitative assessment of its population size. A complete distribution map is also provided establishing its total area of occupancy and maximum extent of occurrence. We find that the species qualifies for a minimum of Vulnerable status on the IUCN Red List, and it potentially qualifies for Critically Endangered status pending confirmation of a continuous population decline. Historical records of predation on the palms by parrots are consistent with current observations indicating that the species is threatened and in need of a management plan for conservation action and long-term monitoring of the stability of the extant population.

The Diatom (Bacillariophyceae) Genus Actinella Lewis in Hawai‘i
Hayden Ripple and J. Patrick Kociolek, 609

Abstract: We review the occurrence of the diatom genus Actinella Lewis in Hawai‘i. Based on collections from the islands of Kaua‘i, Moloka‘i, and Hawai‘i, we have documented the presence of three species of the genus. Using light and scanning electron microscopy, we illustrate these species, two of which are new to science and described here. Actinella punctata Lewis is distinct in having a bulbous headpole with a short extension at the dorsal margin and a large extension on the ventral margin. This species was observed from Hawai‘i and Moloka‘i. Actinella hawaiiensis Ripple & Kociolek, n. sp., is distinguished by its headpole extension being produced from the dorsal margin, whereas A. molokaiensis Ripple & Kociolek, n. sp., has a headpole protuberance near the center of the apex. Both of the new species are found on the islands of Kaua‘i and Molokai‘i. A previously described endemic, A. punctata var. alakaiensis Main, was not encountered in our collections. Three of the four Actinella taxa from Hawai‘i are currently known as endemics and appear to have their closest allies in either North and/or South America, similar to observations for Gyrosigma krammeri Kociolek et al., another diatom species in Hawai‘i. Further research is necessary to determine the biogeographic patterns of the freshwater diatom flora of Hawai‘i.

Index to Volume 67, 623

Association Affairs, 629