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Biology and Impacts of Pacific Island Invasive Species. 4. Verbesina encelioides, Golden Crownbeard (Magnoliopsida: Asteraceae)
Kathleen R. Feenstra and David R. Clements, 161
Verbesina encelioides (Cav.) Benth. & Hook. f. ex A. Gray, golden crownbeard, is a sunflower-like herbaceous annual plant ranging in height from 0.3 to 1.7 m with showy yellow flowers. It is native to the southwestern United States, the Mexican Plateau, and other parts of tropical America. Its invasive characteristics include high seed production (as many as 300–350 seeds per flower and multiple flowers per plant), seed dormancy, ability to tolerate dry conditions, and possible allelopathic effects. Disturbed areas with a relatively sandy substrate within warm, arid climate zones are vulnerable to invasion by V. encelioides. Verbesina encelioides is found on all of the main Hawaiian islands except Ni‘ihau but is particularly problematic on Midway and Kure Atoll, where it may threaten the habitat of nesting birds such as Laysan and black-footed albatrosses and Christmas and wedge-tailed shearwaters. Many other Pacific islands with similar habitats could be invaded by V. encelioides. The plant has become naturalized in many other U.S. states, parts of South America, the Bahamas, Cuba, the Dominican Republic, Puerto Rico, parts of Europe, Saudi Arabia, India, Ethiopia, Morocco, Botswana, Namibia, Israel, and Australia. It is a pest of various crops in the southern United States and India and is poisonous to sheep and cattle. Verbesina encelioides can be controlled via herbicides or mechanical means, but measures must be repeated due to the presence of persistent seed banks. Further research on V. encelioides is needed to understand its population dynamics, allelopathic properties, and impacts on natural ecosystems.
Exploiting Macrofauna Diadromy for Assessing Anthropogenic Impact in American Samoa Streams
L. M. Wade, F. S. Fanolua, A. M. Vargo, K. van Houte-Howes, E. Bardi, and D. L. Vargo, 177
Stream biomonitoring is increasingly used to identify and monitor changes in water quality, stream habitat, and even the surrounding watershed. An effective biomonitoring protocol must comprise attributes able to discriminate human-caused changes from natural variation. We attempted to identify such attributes for streams of American Samoa, which, in turn, might also have widespread applicability to other oceanic islands. Owing to the diadromous nature of the macrofauna, we assessed species richness, diversity, composition, dominance, and biomass of freshwater fishes, crustaceans, and mollusks in 50 m sections in midreaches of five streams with and five streams without anthropogenic influences at the estuarine reach. We electrofished for fishes and crustaceans, and we picked mollusks from stream substrates. We discovered that two species of neritid snails of the pan-Pacific genus Clithon were significantly more abundant in the midreach of streams undisturbed by human impacts at the estuarine reach, making them potentially useful bioindicators throughout the South Pacific.
Life History of the Red Spiny Lobster, Panulirus penicillatus (Decapoda: Palinuridae), in the Galápagos Marine Reserve, Ecuador
Alex Hearn and Juan Carlos Murillo, 191
The red spiny lobster, Panulirus penicillatus (Olivier, 1791), is exploited commercially in the Galápagos Marine Reserve by the local fishing sector. Catches and catch per unit effort have declined over the past few years, leading to concerns about sustainability of the fishery. This study supports the processes regarding the fishery management of P. penicillatus by determining its distribution and growth parameters. Nearly 3,000 lobsters were tagged during surveys carried out at 13 islands between 2000 and 2004. Sex ratio did not differ significantly from 1:1, and tagging returns showed little or no movement of individuals. Mean values with 95% confidence intervals for von Bertalanffy growth parameters were estimated to be K=0.201±0.004, L∞=16.91±0.183 (cm carapace length), and Ф’=4.14±0.019 for males; and K=0.264±0.02, L∞=12.34±0.40 (cm carapace length), and Ф’=4.99±0.06 for females. Natural mortality was 0.342 for males and 0.378 for females. These results, together with comparative estimates for red spiny lobster elsewhere, illustrate the geographical variability of growth among populations of P. penicillatus, which may occur within the archipelago itself.
A Comparison of Immature Green Turtles (Chelonia mydas) Diets among Seven Sites in the Main Hawaiian Islands
Karen E. Arthur and George H. Balazs, 205
Understanding resource acquisition and feeding ecology of threatened species is integral to their conservation because diet is intimately linked with growth rate and reproductive output. We examined diets of immature green sea turtles, Chelonia mydas (L.), from seven sites on the islands of Hawai‘i, O‘ahu, Moloka‘i, and Lāna‘i in January and August 2003. Diet analysis was based on 191 samples collected from 181 live green turtles by stomach lavage. These samples were identified and quantified using dissection microscopy and the principles of microstereology. Diet of green turtles in the Main Hawaiian Islands was dominated by red algae, and diet items most commonly encountered were Acanthophora spicifera (an introduced species), Hypnea sp., Pterocladiella sp., and Cladophora sp. Sea grasses (Halophila hawaiiana and H. decipiens) were an important component of diet in turtles from Kāne‘ohe Bay. Content of green turtle diets differed among foraging grounds, and these differences may provide an insight into previously documented differences in turtle growth rates among sites.
Evolutionary Lineages in Emballonura and Mosia Bats (Mammalia: Microchiroptera) from the Southwestern Pacific
D. J. Colgan and S. Soheili, 219
The microchiropteran bat family Emballonuridae is widely distributed in archipelagos of the southwestern Pacific, with especially strong representation of genera Emballonura and Mosia. DNA sequences from three segments of the mitochondrial genome were collected from four species of Emballonura and from M. nigrescens to investigate the relationship of genetic differentiation to archipelago biogeography. Specimens of each species formed monophyletic clades in maximum parsimony and Bayesian analyses. Mosia nigrescens was genetically distant to the other four species. The other four studied species formed a monophyletic clade composed of the pairs E. beccarii, E. serii and E. raffrayana, E. semicaudata. Clades within species were strongly concordant with geography, with only two counterexamples (E. semicaudata in Fiji and E. raffrayana in the Solomon Islands) to the general finding that each island’s population of a species constitutes a monophyletic clade. Genetic results do not agree with current subspecific designations within M. nigrescens. Samples from Woodlark, Alcester, and Manus Islands are phylogenetically closer to Papuan mainland samples than to Solomon Islands and New Ireland samples supposedly belonging to the same subspecies. Results suggest that Emballonura can establish populations across wide water barriers but does so infrequently. The isolating effect of water barriers is exemplified by the substantial genetic distinctiveness of Solomon Islands and New Ireland populations of both E. raffrayana and M. nigrescens. Absence from New Britain of E. beccarii, E. raffrayana, and E. serii (all known from New Ireland) may also reflect effects of water barriers if not due to collecting artifacts.
Relative Abundance and Distribution of Mariana Swiftlets (Aves: Apodidae) in the Northern Mariana Islands
Justine B. Cruz, Shelly R. Kremer, Gayle Martin, Laura L. Williams, and Vicente A. Camacho, 233
The endangered Mariana Swiftlet, Aerodramus bartschi (Mearns, 1909), occurs in its native habitat on only three islands worldwide—Guam, Saipan, and Aguiguan. It is locally extinct on the islands of Rota and Tinian, and numbers have declined on Guam. On Saipan and Aguiguan, the bird remains common. We present previously unpublished data from reports lodged with the Commonwealth of the Northern Mariana Islands Division of Fish and Wildlife combined with an analysis of arrival count data from surveys conducted regularly on Saipan (1985–2005) and opportunistically on Aguiguan (1985–2002). Direct counts of swiftlets arriving at nesting caves did not permit islandwide population estimates but provided an index useful for assessing relative abundance. On Aguiguan, swiftlets occurred in only a few of the available caves; the population was small, more densely concentrated than on the other islands, and relatively stable. On Saipan, swiftlet numbers declined for the first part of the monitoring period (1985–1992), then increased significantly (1998–2005), and now stand at their highest level (>5,000 birds) since 1985. Large between-year fluctuations, high variation in colony attendance patterns, and occasional abandonment and recolonization of some caves were evident during the 20-yr monitoring period. Of the potential constraints to the population, pesticide use, typhoons and supertyphoons, habitat alteration by feral animals, human disturbance in the nesting caves, and predation remain areas of concern. Conservation measures may have lessened some disturbance events and nest damage by cockroaches, while other measures, such as translocation, may improve the species’ chances of persistence.
A New Small-Bodied Species of Bavayia (Reptilia: Squamata: Diplodactylidae) from Southeastern New Caledonia
Aaron M. Bauer, Todd R. Jackman, Ross A. Sadlier, Glenn Shea, and Anthony H. Whitaker, 247
A new species of diplodactylid genus Bavayia, B. goroensis, is described from the Plaine des Lacs region of the Province Sud, New Caledonia. The new gecko is the smallest member of the Bavayia cyclura clade (49 mm snout-vent length) and, based on a molecular phylogeny, is basal within this group. It differs from other members of this group in its much smaller size, more gracile body, and lower number of precloacal pores and subdigital lamellae. The new species is known from only two locations, one of which is adjacent to extensive nickel mining operations. Because of its limited distribution and the direct and indirect threats posed by the proximity of mining to one of the populations, the species is here regarded as “Endangered.”
Role of Pro-Thrombolites in the Geomorphology of a Coastal Lagoon
D. A. Siqueiros-Beltrones, 257
Thrombolites are lithified biosedimentary structures generated by entrapment, precipitation, and binding of sediments promoted by growth and metabolic activity of cyanobacteria. Beaches of the coastal lagoon known as Ensenada de La Paz in Baja California Sur, México, are bordered by sedimentary formations of cyanobacterial origin identified as pro-thrombolites (incipient thrombolites) that represent a first record for the region and México. Observed thrombolithic structures show grains of varied sizes embedded within a fine-grain micritic matrix, which may be surrounded by medium-grain cementing micrite. Different degrees of consolidation occur—some crumble easily, whereas others require some manual force to break. These pro-thrombolites consist of platforms >20 cm thick and/or fragments of assorted sizes and forms. In some cases the structures have lithified, forming rocky plates (thrombolites). The extension and wide distribution of pro-thrombolites around the La Paz lagoon suggests that these structures could have determined its evolution from an original (primitive) cove into a lagoon. That is, the formation of pro-thrombolites through the entrapment and binding of sediments may have eventually altered water circulation, promoting sand sedimentation causing the formation of the El Mogote sand bar. Likewise, pro-thrombolites may have formed large extensions of headlands through accretion. Thus, several square kilometers of populated land around the La Paz lagoon may have thrombolithic origin.
Additional Marine Benthic Algae from Howland and Baker Islands, Central Pacific
Roy T. Tsuda, Peter S. Vroom, Isabella A. Abbott, Jack R. Fisher, and Kevin B. Foster, 271
Marine benthic algae from Howland Island and Baker Island were identified from collections made during earlier expeditions in 1924, 1935, and 1964, and during five separate expeditions between 1998 and 2004. Eighty-nine (six blue-green algae, 53 red algae, five brown algae, and 25 green algae) of the 99 species represent new records for the two islands. Forty-seven and 86 species are documented with voucher specimens from Howland Island and Baker Island, respectively. This study increases the total number of benthic marine algal species from the two islands to 104 species. A similar number (107 species) was previously reported from the nearby low coral islands in the Phoenix Group located 400 km to the southwest. Only 38% (39 of 104 species) of the algal species from Howland Island and Baker Island are reported from the Phoenix Group. The presence of Udotea palmetta Decaisne on Baker Island is of interest because the record is the first for this green algal genus in the central Pacific region.
Association Affairs, 291
