Life history,distribution and molecular phylogenetics of the Upward-Mouth Spikefish Atrophacanthus japonicus (Teleostei: Tetraodontiformes: Triacanthodidae)

Ninety-six juvenile specimens (37–54 mm standard length; L_S) of the rarely collected Upward-Mouth Spikefish Atrophacanthus japonicus (Triacanthodidae) were obtained from the stomachs of three Yellowfin Tuna Thunnus albacares collected off Guam in the Mariana Islands in the central Pacific Ocean. These specimens extend the range of A. japonicus eastward into Oceania. We review the systematic characters of the monotypic genus Atrophacanthus and present colour photographs of freshly collected specimens. The diet of the juvenile specimens of A. japonicus consisted of thecosome pteropods and foraminiferans. We present a range map of A. japonicus based on all known specimens and show that specimen size is related to whether specimens were collected in the pelagic zone or on the bottom. Our results support that, compared to all other Triacanthodidae, A. japonicus has an unusually extended pelagic larval and juvenile period, up to 54 mm L_S, before settling to the bottom as adults. Lastly, we provide a multilocus phylogeny addressing the phylogenetic placement of Atrophacanthus based on eight of 11 triacanthodid genera and six genetic markers. Our results reveal that Atrophacanthus is the sister group of Macrorhamphosodes and they provide new insights about the evolutionary history of the family.     

Cool temperatures elicit reproduction in a biologically invasive predator,the brown treesnake (Boiga irregularis)

Two different temperature regimes for eliciting reproduction in male and females of the Guam form of the brown treesnake were investigated. Males and females maintained at 24°C followed by a 60‐day cool period at 19°C exhibited substantial reproductive activity, and the females that produced clutches did so during a brief period after return to 24°C. In contrast, individuals maintained at 28°C followed by an identical 19°C cooling period exhibited relatively little reproductive activity, and although some females became vitellogenic, none produced eggs. Reproductive activity was virtually absent in all individuals in both groups 7 months after the end of the cool period. Thus, a period of cool temperatures elicits reproductive activity in both sexes and the effect is transitory. Temperatures experienced during the cool period were much lower than the snakes would experience on Guam, and temperatures there are also relatively invariant. Thus, it is possible that only minor fluctuations in temperature are sufficient to elicit reproduction in the Guam population. Because the Guam form does well under, and responds reproductively to, unusually cold temperatures for a lowland tropical reptile, concern that it may have the capacity to invade extralimital temperate areas is warranted. Zoo Biol 22:227–238, 2003. Published 2003 by Wiley‐Liss, Inc.     

The prehistory and biogeography of terrestrial vertebrates on Guam, Mariana Islands

Aim By establishing a prehistoric fossil record for the vertebrate fauna of Guam, we can document the composition of the island’s fauna prior to Western contact. It will also complement the extensive prehistoric fossil data already known from the nearby islands of Rota, Tinian and Aguiguan, and improve our understanding of natural distributional patterns through a chronologically deeper view of the biogeography of the Mariana Islands. Location Northern Guam, Mariana Islands, Micronesia. Methods Fossil‐bearing sediment was removed from karst features with vertically and horizontally controlled excavation methods. Age determinations of the fossils were estimated by radiocarbon dating associated wood charcoal samples. Results The 3314 bones (fossils) of terrestrial vertebrates date to the past two millennia and represent 34 species. Among 12 species of squamate reptiles, one is extinct (a gekkonid lizard) and another, the monitor lizard, Varanus indicus, was introduced to Guam no later than about 1600 years ago. The 17 species of birds feature five that are extinct. Two others not recorded previously on Guam are extirpated. Eight others were lost on Guam in historic times. We also recovered bones of two species of indigenous bats, (Pteropus sp., extirpated; Emballonura semicaudata, probably extirpated), and non‐native rodents, (Rattus spp.). Main conclusions Guam’s contemporary faunal losses have been well documented since invasion of the Brown Treesnake (Boiga irregularis) during or shortly after WWII. Other exotics, as well as habitat deterioration, have abetted this snake’s deleterious presence. Our data further show that human impact led to declines or losses of vertebrate populations by late prehistoric times. Numerous anthropogenic extirpations would not be evident without studying fossils. Our chrono‐stratigraphic evidence argues for the arrival of non‐native rats (Rattus sp.) only about 1000 years ago, which helps to explain why a flightless rail survived on Guam into modern times, unlike on most other islands in Oceania.     

Distribution of the neurotoxic nonprotein amino acid BMAA in Cycas micronesica

BMAA (β-methylamino-L-alanine), a nonprotein amino acid with neurotoxic properties occurs in the cycad Cycas micronesica Hill in Guam. BMAA may have originally played a role as an antiherbivory compound in the plant, but is now of great interest because of its possible link to ALS-PDC, a neurological disease among the Chamorro people of Guam. Biomagnified cycad neurotoxins may play a role because they accumulate in flying foxes of the genus Pteropus that are eaten during traditional feasts. Since flying foxes feed on the seed sarcotesta it is important to understand the distribution of BMAA in the various tissues of the cycad. Using HPLC techniques, we quantified both BMAA and glutamic acid (GLU) in all cycad tissues. Although GLU is distributed randomly throughout the plant, BMAA is concentrated in cycad reproductive organs, with the highest concentrations being found in the immature staminate sporangium and the outmost layer of the sarcotesta. This finding is consistent with the putative evolutionary role of BMAA as an antiherbivory compound, as well as the biomagnification of the compound in flying foxes that ingest the seed sarcotesta.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 165–168.     

Differences among avian frugivores in seed dispersal to degraded habitats

Vertebrate frugivores enhance tropical forest regeneration by dispersing seeds into degraded areas. However, the importance of individual species as dispersers may vary within a community. Management and restoration would benefit from understanding which species are critical in moving native seeds into degraded habitats. We compared habitat composition of bird start and end locations for movement intervals based on mean gut passage times for the avian frugivore community on the island of Saipan. The proportion of movement intervals that began in intact, native forest varied among species, with Golden White‐eyes having the highest proportion. However, this species tended to remain in intact forest and only rarely crossed into degraded habitats. Bridled White‐eyes and Mariana Fruit Doves exhibited slightly higher rates of crossing from intact forest to degraded habitats, suggesting an ability to disperse native seeds to degraded areas. White‐throated Ground Doves were never recorded crossing from intact forest to degraded habitats. Despite having a low proportion of movement intervals beginning in intact forest, Micronesian Starlings showed a higher proportion and absolute number of movements from intact forest to degraded habitats, due to their propensity to move frequently, across long distances, and across habitat types. In this species‐poor frugivore network, seed dispersal into degraded habitats appears highly dependent on one species within the community. Regeneration of degraded lands may be severely hindered if this key disperser is lost.     

Parasitoids of the corn borerOstrinia furnacalis [Lep.: Pyralidae] in the Mariana Islands

A survey of the parasitoids of the Asian corn borer,Ostrinia furnacalis (Guenee), in the Mariana Islands showed that few of the borers were parasitized. Parasitoids were reared from only 30 pupae out of more than 4 500 sampled. Three species of pupal parasitoids were found:Xanthopimpla punctata (F.),Brachymeria albotibialis (Ashmead) andTetrastichus? inferens Yoshimoto. No parasitoids were reared from mature larvae. The only egg parasitoid observed wasTrichogramma chilonis Ishii. During the month prior to the sweet corn harvest, which was the peak period of moth oviposition, about 40% of the egg masses had at least one egg parasitized. An average of about 35% of the eggs within a mass were parasitized.     

Cancer in Guam and Hawaii: A comparison of two U.S. Island populations

BackgroundCancer disparities within and across populations provide insight into the influence of lifestyle, environment, and genetic factors on cancer risk.MethodsGuam cancer incidence and mortality were compared to that of Hawaii using data from their respective population-based, central cancer registries.ResultsIn 2009–2013, overall cancer incidence was substantially lower in Guam than in Hawaii for both sexes while overall cancer mortality was higher for Guam males. Cervical cancer incidence and prostate cancer mortality were higher in Guam. Both incidence and mortality were higher among Guam men for cancers of the lung & bronchus, liver & intrahepatic bile duct, and nasopharynx; Chamorro men were disproportionately affected by these cancers. Filipinos and Whites in Guam had lower overall cancer incidence compared to Filipinos and Whites in Hawaii. Although breast cancer incidence was significantly lower in Guam compared to Hawaii, women in Guam presented at younger ages and with rarer disease histologies such as inflammatory carcinoma were more prevalent. Guam patients were also diagnosed at younger ages for cancers of bladder, pancreas, colon & rectum, liver & intrahepatic bile duct, lung & bronchus, stomach, non-Hodgkin lymphoma, and leukemia.ConclusionSmoking, infectious agents, and betel nut chewing appear to be important contributors to the burden of cancer in Guam. Earlier onset of cancer in Guam suggests earlier age of exposure to key risk factors and/or a more aggressive pathogenesis. Contrasting cancer patterns within Guam and between Guam and Hawaii underscore the potential influence of genes, lifestyle, and environmental factors on cancer development and progression.     

Passive restoration following ungulate removal in a highly disturbed tropical wet forest devoid of native seed dispersers

Overabundant ungulate populations can alter forests. Concurrently, global declines of seed dispersers may threaten native forest structure and function. On an island largely devoid of native vertebrate seed dispersers, we monitored forest succession for 7 years following ungulate exclusion from a 5‐ha area and adjacent plots with ungulates still present. We observed succession from open scrub to forest and understory cover by non‐native plants declined. Two trees, native Hibiscus tiliaceus and non‐native Leucaena leucocephala, accounted for most forest regeneration, with the latter dominant. Neither species is dependent on animal dispersers nor was there strong evidence that plants dependent on dispersers migrated into the 5‐ha study area. Passive restoration following ungulate removal may facilitate restoration, but did not show promise for fully restoring native forest on Guam. Restoration of native forest plants in bird depopulated areas will likely require active outplanting of native seedlings, control of factors resulting in bird loss, and reintroduction of seed dispersers.     

The “Reservation Effect”: Implications for Background Comparisons

A difficult challenge in ecological risk assessment can be determining what constitutes the “background” or ground-state condition for a site. This is because off-site conditions may not reflect to any relevant degree the history of the site itself and may therefore not be appropriate as benchmarks. One of the more important concerns is that underestimates may be made regarding contaminant-related impacts on-site because observations may indicate that community or population quality on-site equals or surpasses that observed off-site. In other cases, overestimates of the degree of contaminant impact may be made if environmental resources on-site are highly managed or devoid of natural communities. As such, management decisions may be confounded by artifacts of non-toxicant-related human influence and will not necessarily appropriately address the contaminant-related issues. Examples of these conditions are discussed herein.